Kuwait
Content
RESEARCH Physicochemical Characteristics and Pollution Indicators in the Intertidal Zone of Kuwait: Implications for Benthic Ecology
DHIA AL BAKRI* Orange Agricultural College The University of Sydney P. O. Box 883 Orange, NSW 2800, Australia WAJEH KITTANEH Kuwait Institute for Scientific Research P. O. Box 24885 Safat, Kuwait ABSTRACT / The coastal environment of Kuwait has been under considerable stress since the onset of the oil era in the late 1950s and early 1960s. Oil, sewage, and industrial pollution were believed to be the main environmental problems in the coastal zone. The huge oil spill and destruction caused by the Gulf War further complicated those problems. In this article, the temperature, pH, salinity, and total dissolved sulfide (TDS) of the interstitial water in the intertidal zone and the water content and total organic carbon (TOC) of the intertidal sediment were investigated. The purpose of the study was to understand the effect of the physicochemical characteristics on the intertidal benthic ecology and to identify the level and sources of organic pollution in the intertidal zone. The study results indicated that the prevailing harsh environmental conditions, especially high temperature and salinity, restricted benthic fauna diversity and led to the development of a fragile intertidal ecosystem. The fauna inhabiting the intertidal zone was dominated by a few species probably living at their limit of tolerance. Organic pollution was evident mainly in Sulaibikhat Bay and to a lesser extent in Kuwait City waterfront and Shuaiba coast in the south. The pollution was attributed mainly to land-based sources such as the occasional discharge of raw sewage through stormwater outlets, the direct oil spillage, and industrial effluents from refineries, oil terminals, and petrochemical plants. Quantitative analysis was inconclusive in establishing a significant correlation between the chemistry and composition of the benthic fauna. However, close examination of sites with high TOC and TDS concentrations indicated that the benthic fauna in those sites was showing evidence of degradation. A number of strategies were recommended to ensure protection and sustainable management of the coastal environment.
The Kuwaiti mainland coast, which extends for about 350 km (Figure 1), is of vital importance for development in the country. Most of the urban, commercial, industrial, and recreational activities in Kuwait are concentrated within 15 km of the shoreline. Furthermore, the coastal water is virtually the only source of fresh water and energy in the country; several desalination/power plants were established along the shoreline to meet the country’s need for drinking water and electricity. The desalination plants remove the dissolved solids from seawater to make it suitable for domestic purposes; after distillation of the seawater, the salt is returned to the sea. The seawater used for cooling the power plants is also discharged to the sea. The discharge of salt and cooling water may increase temperature and salinity of the coastal water. The coastal area is
KEY WORDS: Intertidal environment; Pollution; Total organic carbon; Dissolved sulfide; Interstitial water; Benthic fauna *Author to whom correspondence should be addressed.
considered a valuable natural resource containing important ecosystems and supporting many organisms, whose extinction may affect the whole marine environment. The coastal zone is also a very important nesting and breeding ground for many resident and migratory birds. As a result of conflicting land uses and intensive development activities, the coastal environment has been subject to considerable stress since the early 1960s. Pollution from oil, sewage, and industry were believed to be the main environmental problems in the coastal zone. Major sources of oil pollution are direct discharge from oil refineries and petrochemical industries, illegal discharge of ballast waters, leakage from oil-exporting terminals and pipes, and accidental releases from offshore drilling (Al-Harmi and Anderlini 1980, Zarba and others 1983, Behbehani 1983). The huge oil spills caused by the Gulf War further complicated the situation. Several studies were carried out in recent years to assess the impact of war’s oil spills on the Arabian Gulf (e.g., Khordagui 1991, Readman and others 1992, ROPME and others 1993, Khordagui and Al-Ajmi 1993,
1998 Springer-Verlag New York Inc.
Environmental Management Vol. 22, No. 3, pp. 415–424
416
D. Al Bakri and W. Kittaneh
Figure 1. Coastal area of Kuwait and location of studied transects (A, B, C, . . ., AG).
Saenger 1994). Sewage pollution was attributed to the misuse of the stormwater outlets to discharge raw sewage to the sea during overflow at the pumping stations of the sewage treatment plants (Al-Mossawi and others, 1980, Literathy and Salem 1983). The discharge of industrial effluents and disposal of semisolid wastes in and near the coastal areas around Shuaiba Industrial Area in the south and the Shuwaikh Port in Kuwait Bay (Figure 1) are other sources of coastal pollution (Samhan and others 1980, Zarba and others 1983). Most of the previous studies focused on investigating the charac-
teristics and pollution of the coastal waters but paid little attention to assessing the physicochemical characteristics and pollution level within the intertidal zone. This article, based on a survey carried out within the context of a multidisciplinary project (Al Bakri and others 1985), provides a detailed assessment of the physical and chemical parameters of the intertidal sediment and interstitial (pore) water of coastal water. This assessment was intended to assist in understanding the effect of the basic physicochemical parameters on the intertidal benthic ecology and to identify levels and
Kuwaiti Intertidal Zone Pollution Indicators
417
sources of organic pollution along the intertidal zone. Temperature, pH, salinity, and total dissolved sulfide (TDS) of the interstitial water and water content and total organic carbon (TOC) of the intertidal sediments were the focus of this study. Such factors affect the migration, reproduction, breeding periods, and metabolic processes of all organisms living in this environmental system. A proper assessment of the physicochemical characteristics is of vital importance to understanding the benthic and coastal life and for monitoring the environmental quality of the coastal zone. The determination of TOC and TDS was intended to provide reliable indicators for delineating areas subject to organic pollution and to identify oil and sewage pollution sources. As the data used in this study were obtained prior to the Gulf War, one of the outcomes will be a benchmark for assessing the long-term impacts of the Gulf War as well as other anthropogenic activities on the intertidal environment.
was carried out according to the methylene blue method (USEPA 1979). Fifty-seven sediment samples, representing the different transects, were analyzed for TOC. Immediately after sampling, the silt–clay fractions were separated by wet sieving on a 230-mesh-size sieve (63 µm), washed with distilled water, dried at 105°C, and powdered. The analytical procedure used for determining the TOC was based on removing the inorganic carbon by acidification and heating, digesting the organic carbon (CO2) with a mixture of potassium dichromate and sulfuric acid, absorbing the liberated CO2 with barium hydroxide, and titrating the excess barium hydroxide by hydrochloric acid. The analytical procedure described in the ROPME manual was followed in this study (ROPME 1983).
Results
Intertidal Sediments According to Al Bakri (1996), the coastal zone of Kuwait is classified into northern and southern provinces, each characterized by unique sedimentological and geomorphologic features. The northern province included transects A–J, whereas the southern province included transects P–AG. The intertidal area, represented by transects I, K, and L at the southern flank of Kuwait Bay, was grouped with the southern province in terms of its sediment type (Figure 1). The northern province is marked by extensive intertidal mudflats, reaching up to 4500 m in width, bounded landward by sabkha flats. Sabkhas are broad, salt-encrusted, supratidal coastal flats bordering sheltered coastal regions (Al Bakri 1994, Cooke and others 1993). The intertidal flats were covered by a mixture of fine sand, silt, and clay. The silt and clay fraction (materials finer than 63 µm) formed between 63.7% and 96.8% whereas sand (material coarser than 63 µ) ranged between 3.2% and 36.3% of the total intertidal sediments. The southern province was characterized by rocky and sandy intertidal flats bounded landward by coastal dunes, coastal ridges, or wave-cut cliffs carved in the old coastal ridges. The intertidal sediments in this province were composed mainly of sand (60–99.5%) with a subordinate amount of silt and clay (0.5–40%). Water Temperature Temperature changes may cause great variation in seawater properties and correspondingly in the life it supports. Variations in water density, salinity, and dissolved oxygen are caused by temperature changes. Growth and reproduction of aquatic life is likely to be
Methods and Materials
The sampling and field measurements were undertaken, during low tides, from the upper, middle, and lower intertidal zones along 35 transects. These transects, imaginary lines perpendicular to the shoreline, were selected to represent the various ecosystems and facies characterizing the coast (Figure 1). With the exception of TOC, all parameters were determined twice, once during the winter and once during the summer of the same year (1984). Sediment samples for TOC were collected only during the winter. At each sampling site a small hole was made to allow the formation of a pool from the interstitial water. Special care was taken to ensure that the surface water did not mix with the interstitial water. A special syringe was used to take two water samples, one for pH and the second for dissolved sulfide. The temperature, salinity, and pH of the water pool were measured in the field by taking the average value of three readings for each parameter. From the same location, two sediment samples were taken from the top 10-cm layer for determining water content, particle size distribution, and TOC. One sample was homogenized and 50 g was dried at 105°C, cooled, and weighed. The loss in weight was expressed as weight percentage of water content. The water samples for determination of TDS were filtered through 0.45-µm membrane filter and then 20 drops of zinc acetate solution (2 N) were added to the bottle before it was filled with the water to preserve the sample. Also 0.5 ml of 6 N sodium hydroxide was added to the sampling bottle to raise the pH above 9. The analytical procedure followed to determine the TDS
418
D. Al Bakri and W. Kittaneh
temperature dependent (Davis 1977). The temperature of the interstitial water was found to vary from season to season and from transect to transect during the same season. In winter, the temperature ranged between 9.5°C and 20.3°C and tended to increase significantly in summer to reach a range of 24.2°C to 35.3°C. The annual average temperature ranged from 18.7 to 24.8°C with a systematic but slight change of up to 2°C across the tidal flat; it was higher near the upper tidal zones and lower near the low water level. The baseline data of the sea (surface) water in the coastal zone in Kuwait indicated that the minimum temperature was 14°C measured in January and the maximum was 33°C recorded in August (EPC/SAA 1985, EPD 1987). When compared with this data baseline, the temperature of the interstitial water was lower in winter and higher in summer than the surface water temperature. Apart from the seasonal and cross-intertidal variations of the temperature, no other distinct trends were apparent. The temperature of the interstitial water is influenced by so many factors that is almost impossible to correlate the variations in its values with any single factor. Atmospheric temperature, time and location of measurements, and exposure to sun radiation were some of the factors that were not possible to control in this investigation and they might have had a significant effect on the recorded temperature. It is believed that changes in the temperature from one site to another or from season to season were largely attributed to these factors. For instance, an extreme low temperature (9.5°C) measured in winter at the upper intertidal zone of transect N could have been caused by the low air temperature that day (5°C). The results indicated that anthropogenic interference had no apparent impact on the interstitial water temperature and that thermal pollution was not evident in any part of the intertidal zone. Salinity The maximum salinity values were recorded in summer (58%–75%) and the minimum range was reported in winter (32%–51.3%). The annual mean values ranged from 36.7% to 44.9%. The level of salinity in the ambient coastal water of Kuwait ranges from 34.5% to 43% and may reach about 51% (EPD 1984, EPC/SAA 1980). These values are higher than those of most world seawater (Al-Awadi and others 1988). In general, the salinity of the interstitial water in Kuwait was found to be high when compared with that of ambient seawater, almost as high as the salinity in the Dead Sea. A considerable degree of fluctuation in salinity was evident and a general trend across the tidal zone in which the salinity decreases from high water to low water levels was apparent. This trend is consistent with the fact that
the upper zone is subject to a higher rate of evaporation, hence the higher salinity, than the lower intertidal zone. This trend was more distinct in the northern province. The significant increase of salinity in summer was caused by high evaporation, due to extremely high atmospheric temperatures and lack of rainfall. Low values recorded at transects A–C and E of Khor Subiya in the north, particularly in the winter (32%–36%), were attributed to the impact of freshwater inflow from the Shatt Al-Arab estuary. This effect is less evident during the summer because the freshwater inflow is considerably reduced. Similar reasoning for the subnormal salinity in the seawater of the northern offshore area of Kuwait was given by Anderlini and others (1982) and Lee (1983). On the other hand, the relatively low values at some sites of transects N, P, R, and W (32%–37%) were attributed primarily to the impact of freshwater and sewage discharged from nearby stormwater outfalls. Exceptionally high salinity levels (45%– 75%) recorded in the upper and middle intertidal sites of northern transects D–I, K, and M were believed to be related to the salt layers encrusting the surface of the surrounding sabkha flats. During spring floods, seawater flushes the sabkhas and removes the salts seaward, leading to an increase in salinity of the interstitial waters. Furthermore, the upper parts of these intertidal stations were not regularly covered with water, so the rate of evaporation and subsequently the salinity of the interstitial water increases. For transects K and M, an additional source of salinity could be the nearby discharges of the Ad-Doha desalination/power plant. Hydrogen Ion Concentration (pH) The pH values of the interstitial water ranged between 6.7 and 8.8 in winter and 6.9 and 8.3 in summer with annual means between 7.2 and 8.2. The readings showed a slight fluctuation from one site to another and from season to season, but there was no evidence of distinct trends that could be explained in terms of the coastal uses and anthropogenic activities. The only consistent difference, although slight, was evident in a north–south direction where the sandy southern intertidal flats tend to have lower pH values than the muddy northern province. The relatively lower pH in the southern province was believed to have been caused by higher CO2 liberation by more active biochemical processes. This argument is consistent with the finding of Al Bakri and others (1996b) that the sandy shores were richer in benthic fauna than the northern muddy shores. This reasoning could also explain why the pH values were lower in the intertidal zone than in the ambient water of the nearshore zone (KISR 1981).
Kuwaiti Intertidal Zone Pollution Indicators
419
Figure 2. Average concentrations of the total organic carbon (TOC) in the intertidal sediment of Kuwait.
Water Content The amount of interstitial water in sediments depends on factors such as particle size, packing, pore space, capillary action, time of sampling, and tidal level (flood or ebb). The water content was found to vary between 2.3% in the upper intertidal zone of transect Y to 55.6% in the lower intertidal zone of transect N with no significant seasonal changes. The annual means were found to range between 11% and 35% with values increasing seaward, i.e., towards the lower intertidal zone. The water content in the northern intertidal mud flats was significantly higher than in the sandy/rocky shores of the south. This pattern is strongly related to the difference in type and particle size of the sediments. The fine sediments of the northern province tend to have a higher water retention than the sand in the south. Total Organic Carbon (TOC) The movement of heavy metals and trace organic pollutants in the aquatic environment is highly dependent on their adsorption–desorption on the suspended and bottom sediments (Khalaf and others 1986). A number of studies have demonstrated that the sorption of hydrophobic organic compounds (such as organochlorine compounds and polycyclic aromatic hydrocarbons) and some heavy metals are well correlated with the organic matter content of the silt–clay fraction (Lambert 1968, Forstner 1977, Thomas and Jacquet 1976). The organic matter in the sediment can be
quantified by measuring the TOC. Therefore, the study of TOC in the fine sediments ( 63 µm) would provide a good indictor of organic pollution and establish a sound basis for understanding the accumulation and release of the trace organics and trace elements (Karichkhoff and others 1979, Khalaf and others 1986). The mean TOC values in the intertidal sediments of Kuwait ranged from 0.20% to 3.10% (Figure 2). The organic matter may have originated from a number of sources such as decay of marine organisms, industrial and domestic effluents, and oil spillage. In order to differentiate the organic matter of natural origin from anthropogenic (pollution) sources and to define levels and sources of pollution, the following approach was employed: The mean ( X) and standard deviation ( ) of the TOC values from transects situated outside the urban and industrial areas, hence less affected by human activities and normally less polluted, were employed to provide the basis for calculating the normal or background level in the study area. These transects included A–I in the north and transects AA to AG in the south (Figure 1). Background (normal) level X 1 0.73 0.51 1.24%
Then the following classification was adopted to define the different pollution levels: 1.25%, background; 1.25%–2.50%, Slightly polluted; and 2.50%, polluted.
420
D. Al Bakri and W. Kittaneh
attributed to natural processes rather than to human activities. All areas classified as polluted or slightly polluted have one feature in common—the presence of stormwater outfalls—and are situated at the main urban and industrial sites. It is believed that the occasional discharge of domestic and industrial effluents through these outfalls as well as oil spillage from nearby oil exporting terminals and ports were the main causes of these high TOC values. At Sulaibikhat Bay, where the maximum concentrations of TOC were recorded, the situation was further complicated by the presence of mud sediment and limited water circulation. These conditions are conducive to attracting and accumulating organic matter discharged through the outfalls or originating from natural processes.
Total Dissolved Sulfide (TDS) Sulfide is a toxic by-product of the anaerobic decomposition of organic matter and commonly is found in sewage and industrial wastes, such as those from petrochemical plants and oil refineries. A major source of sulfide in an aquatic system is the anaerobic decomposition of sewage, sludge, algae, and other naturally deposited organic materials (USEPA 1986). Sulfide can be present as the sulfide ion (S2 ) or as dissolved hydrogen sulfide (H2S and HS ). The toxicity of sulfide, which is derived primarily from H2S, is dependent on the temperature, pH, and dissolved oxygen concentration (USEPA 1986). According to USEPA (1986), water containing 2 µg/liter undissociated hydrogen sulfide (H2S) would not be hazardous to most fish and other aquatic wildlife. The Kuwaiti guidelines for ambient seawater states that the concentration of undissociated hydrogen sulfide should not exceed 2 µg/liter (Al-Awadi and others 1988). The threshold hazard value (THV) for the coastal water at the Shuaiba Industrial Area is 0.01 mg/liter (EPC/SAA 1983). A study carried out around Shuaiba Industrial Area (EPC/SAA 1986) showed that the hydrogen sulfide concentration in the ambient seawater ranged between 0.001 and 0.071 mg/liter, but it was found to be much higher in the industrial and refinery effluents, with maximum values between 2.50 and 8.92 mg/liter. The TDS concentrations in the interstitial water ranged between 0.03 mg/liter (instrument detection limit) and 7.00 mg/liter with annual means of 0.03 to 5.61 mg/liter (Figure 4). As there are no guidelines for TDS concentration in interstitial water, the approach employed in classifying the TOC values was adopted here to allow the use of the TDS values as indicators of
Figure 3. Spatial distribution of the total organic carbon (TOC) in the intertidal sediment
Figure 3 shows the spatial distribution of the different levels of TOC along the coastline of Kuwait. Transects N, O, and J in Sulaibikhat Bay were classified as polluted sites with the highest TOC values in the study area (2.61%–3.10%). The area immediately to the west (transects I, K–M) and east (transects P–R) of those sites and the southern zone represented by transects W–Y show slight organic pollution with values between 1.25% and 2.50%. The remaining areas have TOC values within the background range ( 1.25%) and thus show no evidence of pollution. Within the latter, the TOC values of the northern transects were significantly higher than those of the southern transects (see Figure 2). This difference was primarily caused by the fact that the northern transects were dominated by silt–clay sediments whereas the southern sites were dominated by sand. The northern intertidal flat, therefore, has an inherently higher capacity to attract and accumulate organic matter than the southern shores. This means that the relatively higher TOC in the north was largely
Kuwaiti Intertidal Zone Pollution Indicators
421
Figure 4. Average concentrations of the total dissolved sulfide (TDS) in the interstitial water of the intertidal zone of Kuwait..
the sources and levels of organic and oil pollution in the intertidal zone. Background level X 1 0.15 0.14 0.29mg/liter The following classification was adopted to define the different pollution levels: 0.30 mg/liter, background; 0.30–1.30 mg/liter, slightly polluted; and 1.30 mg/liter, polluted. As shown in Figure 5, the distribution of TDS concentrations along the intertidal zone closely corresponds to those of the TOC values. Transects N, O, J, and Q of Sulaibikhat intertidal mudflats were classified as polluted sites with TDS values between 1.68 and 5.61 mg/liter. Transects M, K, and I and in the southwestern corner of Kuwait Bay, transects P, R–U of the Kuwait City waterfront and the southern transects W–Y and AI showed slight pollution with values between 0.30 and 1.30 mg/liter. The remaining areas have TDS values within the background range ( 0.30 mg/liter) and thus show no evidence of pollution. Within this area, the TDS values of the northern transects were significantly higher than those of the southern transects. This difference was attributed to the difference in particle size of the intertidal sediments. The former transects were dominated by mud, whereas the latter transects were dominated by sand. This means that the relatively higher TDS values in the north were largely attributable to natural processes rather than human activities. It is believed that the occasional discharge of sewage
Figure 5. Spatial distribution of the total dissolved sulfide (TDS) in the interstitial water of the intertidal zone.
422
D. Al Bakri and W. Kittaneh
through the stormwater outfalls and the industrial and oil refinery effluents discharged to coastal water were the main sources of high TDS concentrations in the sites classified as polluted and slightly polluted. At Sulaibikhat Bay, where the highest TDS concentrations were recorded, the situation was further complicated by the presence of mud sediment and limited water circulation. These conditions are conducive to attracting and accumulating pollutants discharged through the outfalls or originated from natural processes.
Discussion
Figures 3 and 5 show a distinct correlation between the distribution of TOC and TDS values along the intertidal zone. The maximum concentrations of both parameters were recorded in Sulaibikhat Bay followed by the Kuwait City waterfront and Shuaiba Industrial Area coast. The organic and oil pollution evident in these sites was attributed to the occasional sewage discharge through stormwater outfalls, the direct oil spillage, and the industrial and refinery effluents at Shuwaikh Port and Shuaiba area. Comparing the results of this study with published data on the offshore area (Jacob and others 1982, Anderlini and others 1982, Abdul Razzaq and others 1982, Literathy and Salem 1986) revealed that salinity, TOC, and temperature in the summer were higher in the intertidal zone than in the subtidal area. In the winter temperature and pH were lower in the intertidal zone. These differences were attributed to the proximity of the intertidal zone to land-based sources of pollution, its exposure to air for long periods twice a day, and its higher level of biochemical processes. According to Al Bakri and others (1985), the benthic fauna community inhabiting the intertidal zone of Kuwait was considered impoverished and characterized by low diversity when compared with intertidal communities elsewhere. Large sections of the intertidal flats were inhabited by a single or a few species. The paucity of organisms has been attributed primarily to harsh environmental conditions, especially high temperature and salinity (Basson and others 1977, Clayton 1982, Jones 1982). Al Bakri and others (1997a,b) employed multivariate analysis and cluster analysis (SAS Institute 1982) to determine the interrelationships and interactions of the chemistry, sediments, and benthic fauna of the intertidal zone. Annual means of the chemical parameters were clustered by both the FASTCLUS procedure and the Bray-Curtise dissimilarity measure. Results from both procedures showed considerable regularity across all stations. The average chemistry of the stations was found to be similar, with a similarity
index of 0.814. Multivariate analysis of variance, canonical correlation, and canonical discriminant analysis have also shown that there was no significant correlation between the mean chemical parameters and the number of taxa and mean density of the benthic fauna. However, these analyses indicated that mud correlates moderately with water content, pH, TDS, and TOC. The quantitative analysis indicated that chemistry was not a determining factor in the overall distribution or composition of the intertidal organisms. However, qualitative examination of areas with maximum concentrations of TOC and TDS revealed that their fauna communities were showing sign of degradation in terms of taxa number and individual density when compared with areas of similar physical and sedimentological characteristics but relatively little pollution. Close qualitative examination of individual stations with abnormally high salinity and temperatures in the upper intertidal zone also revealed evidence of some impact on the number of taxa and abundance of some species. Based on the finding of this study and evidence from previous studies, it can be argued that the intertidal benthic community is dominated by a few tolerant species, which are probably living at the limit of their tolerance to harsh environmental conditions. It seems that the discharge of sewage, oil, and industrial effluents has a limited effect on the overall composition of the intertidal benthic fauna at the time of completing this survey. It should be borne in mind, however, that the lack of baseline data prior to this study does not allow for accurate identification of possible changes or deterioration in the ecosystem that might have occurred as a result of the intensive development activities since the 1960s. It is very likely that the discharge of untreated sewage and industrial wastes as well as oil spillage may lead, in the long term, to significant accumulation of pollutants and subsequently to serious damage to the coastal environment. It is recommended, therefore, that current disposal practices be controlled and closely monitored.
Conclusions
The exceptionally high salinity and temperature of the interstitial water and relative lack of hard substrates in the intertidal zone restricted the diversity of benthic fauna and led to the dominance of a few species probably living at the limit of their tolerance. These harsh environmental conditions made the intertidal ecosystem inherently fragile. Sections of the intertidal zone, mainly Sulaibikhat Bay and, to a lesser extent, the Kuwait City waterfront and Shuaiba coast in the south, were showing evidence of sewage and oil pollution. This
Kuwaiti Intertidal Zone Pollution Indicators
423
pollution was primarily attributed to land-based sources such as the occasional discharge of sewage through the stormwater outfalls, industrial effluents, and oil spillage from exporting oil terminals and refineries. Although statistical analysis indicated that the relatively high TOC and TDS were not detrimental to the overall composition of benthic fauna, close examination of the situation provided evidence that the intertidal ecosystem in those areas was under stress. Continuing anthropogenic discharge will certainly lead, in the long term, to irreversible damage to this fragile ecosystem. It is recommended that environmental policies must be stringently applied to stop these highly undesirable and harmful disposal practices. Furthermore, the discharges of stormwater outfalls and industrial effluents as well as the intertidal ecosystems in sites showing high TOC and TDS concentrations should be closely monitored and assessed to ensure that the situation will not deteriorate any further. Results of this study are of particular value for future monitoring and assessment of coastal pollution and other environmental hazards. Studies to assess trace metals and trace organics in the coastal zone should focus on sites that show high concentrations of TOC and TDS. This article, together with those of Al Bakri (1996) and Al Bakri and others (1997a,b) provide a comprehensive assessment of the physical, chemical, and biological aspects of the intertidal zone of Kuwait and thus establish a very useful benchmark for evaluating the long-term environmental impact on this sensitive ecosystem, particularly those impacts caused by the Gulf War. It is also recommended that the findings of these studies be integrated into the coastal management process to ensure protection of the coastal environment and development of a sustainable coastal management system.
Al-Awadi, F., M. Ghaleb, G. Mehdirata, D. Al Bakri, and others. 1988. Environmental protection standards and guidelines for the State of Kuwait: Ambient sea water quality standards. Environment Protection Council, Kuwait, 165 pp. Al Bakri, D. 1994. A geomorphic framework for developing a sustainable greenery program in arid environment. The Environmentalist 14(4):271–282. Al Bakri, D. 1996. A geomorphological approach to sustainable planning and management of the coastal zone of Kuwait. Geomorphology 17:323–337. Al Bakri, D., M. Foda, M. Behbehani, F. Khalaf, W. Shublaq, and A. Khuraibet. 1985. Environmental assessment of the intertidal zone of Kuwait. Research report, volumes 1 and 2. KISR 1687. Kuwait Institute for Scientific Research, Kuwait, 429 pp. Al Bakri, D., A. Khuraibet, and M. Behbehani. 1997a. Quantitative assessment of the intertidal environment of Kuwait—I: Integrated environmental classification. Journal of Environmental Management (in press). Al Bakri, D., M. Behbehani, and A. Khuraibet. 1997b. Quantitative assessment of the intertidal environment of Kuwait— II: Controlling factors. Journal of Environmental Management (in press). Al-Harmi, L., and V. Anderlini. 1980. A survey of tar pollution on beaches of Kuwait. Annual research report, 1979. Kuwait Institute for Scientific Research, pp 82–85. Al-Mossawi, M., W. Awadh, and M. Salama. 1980. Incidence of antibiotic resistant fecal coliform bacteria in Kuwait coastal waters. Annual research report, 1979. Kuwait Institute for Scientific Research, pp 85–87. Anderlini, V. C., P. Jacob, and J. Lee. 1982. Atlas of physical and chemical oceanographic characteristics of Kuwait Bay. KISR 704. Kuwait Institute for Scientific Research, Kuwait. Basson, P. W., J. E. Burchard, J. T. Hardy, and A. R. Price. 1977. Biotopes of the western Arabian Gulf: Marine life and environments of Saudi Arabia. Arabian American Oil Co., Dhahran, Saudi Arabia. Behbehani, M. 1983. Oil pollution in the ROPME sea area with special reference to recent incidence. A paper presented at Mabahiss—John Murray international symposium of marine science of the northwest Indian Ocean and adjacent water, 3–6 September, Alexandria, Egypt. Clayton, D. A. 1982. Ecology of mudflats with particular reference to those of the north Arabian Gulf. The first conference on environment and pollution, Kuwait, 7–9 February 1982. Cooke, R. U., A. Warren, and A. Goudie. 1993. Desert geomorphology. UCL press, London. Davis, R. A. 1977. Principles of oceanography, 2nd ed. AddisonWesley Publishing, New York. EPC/SAA. 1980. Salinity in Doha and Shuwaikh from 1979 to 1980. Environment Protection Centre, Shuaiba Area Authority, Kuwait. EPC/SAA. 1983. Code of industrial services at Shuaiba Industrial area—code of practice and environmental guidelines. Environment Protection Centre, Shuaiba Area Authority, Kuwait. EPC/SAA. 1985. Annual reports 1984–1985. Environment Protection Centre, Shuaiba Area Authority, Kuwait.
ACKNOWLEDGMENTS
This article is based on data obtained from a research project funded by the Environment Protection Council of Kuwait and carried out at the Kuwait Institute for Scientific Research. Special thanks are extended to the team members of project EES-35 for their valuable contributions throughout the study. Thanks are also extended to Mrs. Liz Greer for preparation of Figures 3 and 5.
Literature Cited
Abdul Razzaq, S., F. Khalaf, D. Al Bakri, and others. 1982. Marine sedimentology and benthic ecology of Kuwait marine environment. KISR 694. Kuwait Institute for Scientific Research, Kuwait.
424
D. Al Bakri and W. Kittaneh
EPC/SAA. 1986. Assessment of sulfide in sea water, February— March 1986 and Shuaiba refinery outlet, April 1985— March 1986. Environment Protection Centre, Shuaiba Area Authority, Kuwait. EPD. 1984. Annual report 1984. Environment Protection Department, Ministry of Public Health, Kuwait. EPD. 1987. Annual reports 1985–1987. Environment Protection Department, Ministry of Public Health, Kuwait. Forstner, U. 1977. Metal concentration in fresh water sediments, natural background and cultural effects, Pages 94– 103 in H. L. Golterman (ed.), Interactions between sediments and fresh water. The Hague. Jacob, P., M. Zarba, and O. Mohammad. 1982. Water quality characteristics of selected beaches of Kuwait. Indian Journal of Marine Science 11:233–238. Jones, D. 1982. Ecology of the rocky and sandy shores of Kuwait. First conference on environment and pollution, 7–9 February, Kuwait. Karichkhoff, S. W., D. S. Brown, and T. A. Scot. 1979. Sorption of hydrophobic pollutants. Water Research 13:241–248. Khalaf, F., P. Literathy, D. Al Bakri, and A. Al-Ghadban. 1986. Total organic carbon in the marine bottom sediments off Kuwait, Pages 117–126 in D. Halwagy, D. Clayton, and M. Behbehani (eds.), Marine environment and pollution of the Arabian Gulf. Kuwait University, Kuwait. Khordagui, H. 1991. Comments on current environmental events in Kuwait. Environmental Management 15(4):455–459. Khordagui, H., and D. Al-Ajmi. 1993. Environmental impact of the Gulf War: An integrated preliminary assessment. Environmental Management 17(4):557–562. KISR. 1981. Oceanographic monitoring program in Shuaiba offshore area. Kuwait Institute for Scientific Research, Kuwait. Lambert, S. M. 1968. Omega, a useful index of soil sorption equilibria. Journal of Agricultural Food Chemistry 16(2):340– 343. Lee, J. W. 1983. Oceanographic characteristics of Kuwait waters in 1981. Pages 11–16 in Proceeding of third shrimp
and fine fisheries management workshop, 4–5 December 1981. Kuwait Institute for Scientific Research, Kuwait. Literathy, P., and A. Salem. 1983. Effects of pollutants on water quality: Fish kills. KISR 2355. Kuwait Institute of Scientific Research, Kuwait. Readman, J. W., S. W. Fowler, J. P. Villeneuve, C. Cattini, B. Oregioni, and L. D. Mee. 1992. Oil and combustion-product contamination of the Gulf marine environment following the war. Nature 358:662–665. ROPME. 1983. Manual of oceanographic observations and pollutant analyses methods. Regional Organisation for the Protection of Marine Environment, Al-Safat, Kuwait. ROPME, IOC (UNESCO), UNEP, NOAA, EPC. 1993. Final report of the scientific workshop on the results of the R/V Mt. Mitchell cruise in the ROPME sea area, vol. 1. Regional Organisation for the Protection of Marine Environment, 24–28 January 1993, Kuwait. Saenger, P. 1994. Cleaning up of the Arabian Gulf: Aftermath of an oil spill. Search 25(1):19–22. Samhan, O., V. Anderlini, and M. Zarbra. 1980. Preliminary investigation of the trace metal levels in the sediments of Kuwait. Pages 93– 96. Annual research report, 1979. Kuwait Institute for Scientific research, Kuwait. SAS Institute. 1982. SAS user’s guide: Statistics, 1982. SAS Institute Inc., Cary, North Carolina. Thomas, S. M., and J. M. Jacquet. 1976. Mercury in the surficial sediments of Lake Erie. Journal of the Fishery Research Board of Canada 33:404–412. USEPA. 1979. Methods of chemical analysis of water and wastes. Report No. 600/4-79-020. US Environmental Protection Agency, Washington, DC. USEPA. 1986. Quality criteria for water—1986. US Environmental Protection Agency, Washington DC. Zarba, M., V. Anderlini, L. Literathy, and F. Shunbo. 1983. Distribution of petroleum hydrocarbons in marine sediments of Kuwait. Pages 150–152. Annual research report, 1982. Kuwait Institute for Scientific Research, Kuwait.
DHIA AL BAKRI* Orange Agricultural College The University of Sydney P. O. Box 883 Orange, NSW 2800, Australia WAJEH KITTANEH Kuwait Institute for Scientific Research P. O. Box 24885 Safat, Kuwait ABSTRACT / The coastal environment of Kuwait has been under considerable stress since the onset of the oil era in the late 1950s and early 1960s. Oil, sewage, and industrial pollution were believed to be the main environmental problems in the coastal zone. The huge oil spill and destruction caused by the Gulf War further complicated those problems. In this article, the temperature, pH, salinity, and total dissolved sulfide (TDS) of the interstitial water in the intertidal zone and the water content and total organic carbon (TOC) of the intertidal sediment were investigated. The purpose of the study was to understand the effect of the physicochemical characteristics on the intertidal benthic ecology and to identify the level and sources of organic pollution in the intertidal zone. The study results indicated that the prevailing harsh environmental conditions, especially high temperature and salinity, restricted benthic fauna diversity and led to the development of a fragile intertidal ecosystem. The fauna inhabiting the intertidal zone was dominated by a few species probably living at their limit of tolerance. Organic pollution was evident mainly in Sulaibikhat Bay and to a lesser extent in Kuwait City waterfront and Shuaiba coast in the south. The pollution was attributed mainly to land-based sources such as the occasional discharge of raw sewage through stormwater outlets, the direct oil spillage, and industrial effluents from refineries, oil terminals, and petrochemical plants. Quantitative analysis was inconclusive in establishing a significant correlation between the chemistry and composition of the benthic fauna. However, close examination of sites with high TOC and TDS concentrations indicated that the benthic fauna in those sites was showing evidence of degradation. A number of strategies were recommended to ensure protection and sustainable management of the coastal environment.
The Kuwaiti mainland coast, which extends for about 350 km (Figure 1), is of vital importance for development in the country. Most of the urban, commercial, industrial, and recreational activities in Kuwait are concentrated within 15 km of the shoreline. Furthermore, the coastal water is virtually the only source of fresh water and energy in the country; several desalination/power plants were established along the shoreline to meet the country’s need for drinking water and electricity. The desalination plants remove the dissolved solids from seawater to make it suitable for domestic purposes; after distillation of the seawater, the salt is returned to the sea. The seawater used for cooling the power plants is also discharged to the sea. The discharge of salt and cooling water may increase temperature and salinity of the coastal water. The coastal area is
KEY WORDS: Intertidal environment; Pollution; Total organic carbon; Dissolved sulfide; Interstitial water; Benthic fauna *Author to whom correspondence should be addressed.
considered a valuable natural resource containing important ecosystems and supporting many organisms, whose extinction may affect the whole marine environment. The coastal zone is also a very important nesting and breeding ground for many resident and migratory birds. As a result of conflicting land uses and intensive development activities, the coastal environment has been subject to considerable stress since the early 1960s. Pollution from oil, sewage, and industry were believed to be the main environmental problems in the coastal zone. Major sources of oil pollution are direct discharge from oil refineries and petrochemical industries, illegal discharge of ballast waters, leakage from oil-exporting terminals and pipes, and accidental releases from offshore drilling (Al-Harmi and Anderlini 1980, Zarba and others 1983, Behbehani 1983). The huge oil spills caused by the Gulf War further complicated the situation. Several studies were carried out in recent years to assess the impact of war’s oil spills on the Arabian Gulf (e.g., Khordagui 1991, Readman and others 1992, ROPME and others 1993, Khordagui and Al-Ajmi 1993,
1998 Springer-Verlag New York Inc.
Environmental Management Vol. 22, No. 3, pp. 415–424
416
D. Al Bakri and W. Kittaneh
Figure 1. Coastal area of Kuwait and location of studied transects (A, B, C, . . ., AG).
Saenger 1994). Sewage pollution was attributed to the misuse of the stormwater outlets to discharge raw sewage to the sea during overflow at the pumping stations of the sewage treatment plants (Al-Mossawi and others, 1980, Literathy and Salem 1983). The discharge of industrial effluents and disposal of semisolid wastes in and near the coastal areas around Shuaiba Industrial Area in the south and the Shuwaikh Port in Kuwait Bay (Figure 1) are other sources of coastal pollution (Samhan and others 1980, Zarba and others 1983). Most of the previous studies focused on investigating the charac-
teristics and pollution of the coastal waters but paid little attention to assessing the physicochemical characteristics and pollution level within the intertidal zone. This article, based on a survey carried out within the context of a multidisciplinary project (Al Bakri and others 1985), provides a detailed assessment of the physical and chemical parameters of the intertidal sediment and interstitial (pore) water of coastal water. This assessment was intended to assist in understanding the effect of the basic physicochemical parameters on the intertidal benthic ecology and to identify levels and
Kuwaiti Intertidal Zone Pollution Indicators
417
sources of organic pollution along the intertidal zone. Temperature, pH, salinity, and total dissolved sulfide (TDS) of the interstitial water and water content and total organic carbon (TOC) of the intertidal sediments were the focus of this study. Such factors affect the migration, reproduction, breeding periods, and metabolic processes of all organisms living in this environmental system. A proper assessment of the physicochemical characteristics is of vital importance to understanding the benthic and coastal life and for monitoring the environmental quality of the coastal zone. The determination of TOC and TDS was intended to provide reliable indicators for delineating areas subject to organic pollution and to identify oil and sewage pollution sources. As the data used in this study were obtained prior to the Gulf War, one of the outcomes will be a benchmark for assessing the long-term impacts of the Gulf War as well as other anthropogenic activities on the intertidal environment.
was carried out according to the methylene blue method (USEPA 1979). Fifty-seven sediment samples, representing the different transects, were analyzed for TOC. Immediately after sampling, the silt–clay fractions were separated by wet sieving on a 230-mesh-size sieve (63 µm), washed with distilled water, dried at 105°C, and powdered. The analytical procedure used for determining the TOC was based on removing the inorganic carbon by acidification and heating, digesting the organic carbon (CO2) with a mixture of potassium dichromate and sulfuric acid, absorbing the liberated CO2 with barium hydroxide, and titrating the excess barium hydroxide by hydrochloric acid. The analytical procedure described in the ROPME manual was followed in this study (ROPME 1983).
Results
Intertidal Sediments According to Al Bakri (1996), the coastal zone of Kuwait is classified into northern and southern provinces, each characterized by unique sedimentological and geomorphologic features. The northern province included transects A–J, whereas the southern province included transects P–AG. The intertidal area, represented by transects I, K, and L at the southern flank of Kuwait Bay, was grouped with the southern province in terms of its sediment type (Figure 1). The northern province is marked by extensive intertidal mudflats, reaching up to 4500 m in width, bounded landward by sabkha flats. Sabkhas are broad, salt-encrusted, supratidal coastal flats bordering sheltered coastal regions (Al Bakri 1994, Cooke and others 1993). The intertidal flats were covered by a mixture of fine sand, silt, and clay. The silt and clay fraction (materials finer than 63 µm) formed between 63.7% and 96.8% whereas sand (material coarser than 63 µ) ranged between 3.2% and 36.3% of the total intertidal sediments. The southern province was characterized by rocky and sandy intertidal flats bounded landward by coastal dunes, coastal ridges, or wave-cut cliffs carved in the old coastal ridges. The intertidal sediments in this province were composed mainly of sand (60–99.5%) with a subordinate amount of silt and clay (0.5–40%). Water Temperature Temperature changes may cause great variation in seawater properties and correspondingly in the life it supports. Variations in water density, salinity, and dissolved oxygen are caused by temperature changes. Growth and reproduction of aquatic life is likely to be
Methods and Materials
The sampling and field measurements were undertaken, during low tides, from the upper, middle, and lower intertidal zones along 35 transects. These transects, imaginary lines perpendicular to the shoreline, were selected to represent the various ecosystems and facies characterizing the coast (Figure 1). With the exception of TOC, all parameters were determined twice, once during the winter and once during the summer of the same year (1984). Sediment samples for TOC were collected only during the winter. At each sampling site a small hole was made to allow the formation of a pool from the interstitial water. Special care was taken to ensure that the surface water did not mix with the interstitial water. A special syringe was used to take two water samples, one for pH and the second for dissolved sulfide. The temperature, salinity, and pH of the water pool were measured in the field by taking the average value of three readings for each parameter. From the same location, two sediment samples were taken from the top 10-cm layer for determining water content, particle size distribution, and TOC. One sample was homogenized and 50 g was dried at 105°C, cooled, and weighed. The loss in weight was expressed as weight percentage of water content. The water samples for determination of TDS were filtered through 0.45-µm membrane filter and then 20 drops of zinc acetate solution (2 N) were added to the bottle before it was filled with the water to preserve the sample. Also 0.5 ml of 6 N sodium hydroxide was added to the sampling bottle to raise the pH above 9. The analytical procedure followed to determine the TDS
418
D. Al Bakri and W. Kittaneh
temperature dependent (Davis 1977). The temperature of the interstitial water was found to vary from season to season and from transect to transect during the same season. In winter, the temperature ranged between 9.5°C and 20.3°C and tended to increase significantly in summer to reach a range of 24.2°C to 35.3°C. The annual average temperature ranged from 18.7 to 24.8°C with a systematic but slight change of up to 2°C across the tidal flat; it was higher near the upper tidal zones and lower near the low water level. The baseline data of the sea (surface) water in the coastal zone in Kuwait indicated that the minimum temperature was 14°C measured in January and the maximum was 33°C recorded in August (EPC/SAA 1985, EPD 1987). When compared with this data baseline, the temperature of the interstitial water was lower in winter and higher in summer than the surface water temperature. Apart from the seasonal and cross-intertidal variations of the temperature, no other distinct trends were apparent. The temperature of the interstitial water is influenced by so many factors that is almost impossible to correlate the variations in its values with any single factor. Atmospheric temperature, time and location of measurements, and exposure to sun radiation were some of the factors that were not possible to control in this investigation and they might have had a significant effect on the recorded temperature. It is believed that changes in the temperature from one site to another or from season to season were largely attributed to these factors. For instance, an extreme low temperature (9.5°C) measured in winter at the upper intertidal zone of transect N could have been caused by the low air temperature that day (5°C). The results indicated that anthropogenic interference had no apparent impact on the interstitial water temperature and that thermal pollution was not evident in any part of the intertidal zone. Salinity The maximum salinity values were recorded in summer (58%–75%) and the minimum range was reported in winter (32%–51.3%). The annual mean values ranged from 36.7% to 44.9%. The level of salinity in the ambient coastal water of Kuwait ranges from 34.5% to 43% and may reach about 51% (EPD 1984, EPC/SAA 1980). These values are higher than those of most world seawater (Al-Awadi and others 1988). In general, the salinity of the interstitial water in Kuwait was found to be high when compared with that of ambient seawater, almost as high as the salinity in the Dead Sea. A considerable degree of fluctuation in salinity was evident and a general trend across the tidal zone in which the salinity decreases from high water to low water levels was apparent. This trend is consistent with the fact that
the upper zone is subject to a higher rate of evaporation, hence the higher salinity, than the lower intertidal zone. This trend was more distinct in the northern province. The significant increase of salinity in summer was caused by high evaporation, due to extremely high atmospheric temperatures and lack of rainfall. Low values recorded at transects A–C and E of Khor Subiya in the north, particularly in the winter (32%–36%), were attributed to the impact of freshwater inflow from the Shatt Al-Arab estuary. This effect is less evident during the summer because the freshwater inflow is considerably reduced. Similar reasoning for the subnormal salinity in the seawater of the northern offshore area of Kuwait was given by Anderlini and others (1982) and Lee (1983). On the other hand, the relatively low values at some sites of transects N, P, R, and W (32%–37%) were attributed primarily to the impact of freshwater and sewage discharged from nearby stormwater outfalls. Exceptionally high salinity levels (45%– 75%) recorded in the upper and middle intertidal sites of northern transects D–I, K, and M were believed to be related to the salt layers encrusting the surface of the surrounding sabkha flats. During spring floods, seawater flushes the sabkhas and removes the salts seaward, leading to an increase in salinity of the interstitial waters. Furthermore, the upper parts of these intertidal stations were not regularly covered with water, so the rate of evaporation and subsequently the salinity of the interstitial water increases. For transects K and M, an additional source of salinity could be the nearby discharges of the Ad-Doha desalination/power plant. Hydrogen Ion Concentration (pH) The pH values of the interstitial water ranged between 6.7 and 8.8 in winter and 6.9 and 8.3 in summer with annual means between 7.2 and 8.2. The readings showed a slight fluctuation from one site to another and from season to season, but there was no evidence of distinct trends that could be explained in terms of the coastal uses and anthropogenic activities. The only consistent difference, although slight, was evident in a north–south direction where the sandy southern intertidal flats tend to have lower pH values than the muddy northern province. The relatively lower pH in the southern province was believed to have been caused by higher CO2 liberation by more active biochemical processes. This argument is consistent with the finding of Al Bakri and others (1996b) that the sandy shores were richer in benthic fauna than the northern muddy shores. This reasoning could also explain why the pH values were lower in the intertidal zone than in the ambient water of the nearshore zone (KISR 1981).
Kuwaiti Intertidal Zone Pollution Indicators
419
Figure 2. Average concentrations of the total organic carbon (TOC) in the intertidal sediment of Kuwait.
Water Content The amount of interstitial water in sediments depends on factors such as particle size, packing, pore space, capillary action, time of sampling, and tidal level (flood or ebb). The water content was found to vary between 2.3% in the upper intertidal zone of transect Y to 55.6% in the lower intertidal zone of transect N with no significant seasonal changes. The annual means were found to range between 11% and 35% with values increasing seaward, i.e., towards the lower intertidal zone. The water content in the northern intertidal mud flats was significantly higher than in the sandy/rocky shores of the south. This pattern is strongly related to the difference in type and particle size of the sediments. The fine sediments of the northern province tend to have a higher water retention than the sand in the south. Total Organic Carbon (TOC) The movement of heavy metals and trace organic pollutants in the aquatic environment is highly dependent on their adsorption–desorption on the suspended and bottom sediments (Khalaf and others 1986). A number of studies have demonstrated that the sorption of hydrophobic organic compounds (such as organochlorine compounds and polycyclic aromatic hydrocarbons) and some heavy metals are well correlated with the organic matter content of the silt–clay fraction (Lambert 1968, Forstner 1977, Thomas and Jacquet 1976). The organic matter in the sediment can be
quantified by measuring the TOC. Therefore, the study of TOC in the fine sediments ( 63 µm) would provide a good indictor of organic pollution and establish a sound basis for understanding the accumulation and release of the trace organics and trace elements (Karichkhoff and others 1979, Khalaf and others 1986). The mean TOC values in the intertidal sediments of Kuwait ranged from 0.20% to 3.10% (Figure 2). The organic matter may have originated from a number of sources such as decay of marine organisms, industrial and domestic effluents, and oil spillage. In order to differentiate the organic matter of natural origin from anthropogenic (pollution) sources and to define levels and sources of pollution, the following approach was employed: The mean ( X) and standard deviation ( ) of the TOC values from transects situated outside the urban and industrial areas, hence less affected by human activities and normally less polluted, were employed to provide the basis for calculating the normal or background level in the study area. These transects included A–I in the north and transects AA to AG in the south (Figure 1). Background (normal) level X 1 0.73 0.51 1.24%
Then the following classification was adopted to define the different pollution levels: 1.25%, background; 1.25%–2.50%, Slightly polluted; and 2.50%, polluted.
420
D. Al Bakri and W. Kittaneh
attributed to natural processes rather than to human activities. All areas classified as polluted or slightly polluted have one feature in common—the presence of stormwater outfalls—and are situated at the main urban and industrial sites. It is believed that the occasional discharge of domestic and industrial effluents through these outfalls as well as oil spillage from nearby oil exporting terminals and ports were the main causes of these high TOC values. At Sulaibikhat Bay, where the maximum concentrations of TOC were recorded, the situation was further complicated by the presence of mud sediment and limited water circulation. These conditions are conducive to attracting and accumulating organic matter discharged through the outfalls or originating from natural processes.
Total Dissolved Sulfide (TDS) Sulfide is a toxic by-product of the anaerobic decomposition of organic matter and commonly is found in sewage and industrial wastes, such as those from petrochemical plants and oil refineries. A major source of sulfide in an aquatic system is the anaerobic decomposition of sewage, sludge, algae, and other naturally deposited organic materials (USEPA 1986). Sulfide can be present as the sulfide ion (S2 ) or as dissolved hydrogen sulfide (H2S and HS ). The toxicity of sulfide, which is derived primarily from H2S, is dependent on the temperature, pH, and dissolved oxygen concentration (USEPA 1986). According to USEPA (1986), water containing 2 µg/liter undissociated hydrogen sulfide (H2S) would not be hazardous to most fish and other aquatic wildlife. The Kuwaiti guidelines for ambient seawater states that the concentration of undissociated hydrogen sulfide should not exceed 2 µg/liter (Al-Awadi and others 1988). The threshold hazard value (THV) for the coastal water at the Shuaiba Industrial Area is 0.01 mg/liter (EPC/SAA 1983). A study carried out around Shuaiba Industrial Area (EPC/SAA 1986) showed that the hydrogen sulfide concentration in the ambient seawater ranged between 0.001 and 0.071 mg/liter, but it was found to be much higher in the industrial and refinery effluents, with maximum values between 2.50 and 8.92 mg/liter. The TDS concentrations in the interstitial water ranged between 0.03 mg/liter (instrument detection limit) and 7.00 mg/liter with annual means of 0.03 to 5.61 mg/liter (Figure 4). As there are no guidelines for TDS concentration in interstitial water, the approach employed in classifying the TOC values was adopted here to allow the use of the TDS values as indicators of
Figure 3. Spatial distribution of the total organic carbon (TOC) in the intertidal sediment
Figure 3 shows the spatial distribution of the different levels of TOC along the coastline of Kuwait. Transects N, O, and J in Sulaibikhat Bay were classified as polluted sites with the highest TOC values in the study area (2.61%–3.10%). The area immediately to the west (transects I, K–M) and east (transects P–R) of those sites and the southern zone represented by transects W–Y show slight organic pollution with values between 1.25% and 2.50%. The remaining areas have TOC values within the background range ( 1.25%) and thus show no evidence of pollution. Within the latter, the TOC values of the northern transects were significantly higher than those of the southern transects (see Figure 2). This difference was primarily caused by the fact that the northern transects were dominated by silt–clay sediments whereas the southern sites were dominated by sand. The northern intertidal flat, therefore, has an inherently higher capacity to attract and accumulate organic matter than the southern shores. This means that the relatively higher TOC in the north was largely
Kuwaiti Intertidal Zone Pollution Indicators
421
Figure 4. Average concentrations of the total dissolved sulfide (TDS) in the interstitial water of the intertidal zone of Kuwait..
the sources and levels of organic and oil pollution in the intertidal zone. Background level X 1 0.15 0.14 0.29mg/liter The following classification was adopted to define the different pollution levels: 0.30 mg/liter, background; 0.30–1.30 mg/liter, slightly polluted; and 1.30 mg/liter, polluted. As shown in Figure 5, the distribution of TDS concentrations along the intertidal zone closely corresponds to those of the TOC values. Transects N, O, J, and Q of Sulaibikhat intertidal mudflats were classified as polluted sites with TDS values between 1.68 and 5.61 mg/liter. Transects M, K, and I and in the southwestern corner of Kuwait Bay, transects P, R–U of the Kuwait City waterfront and the southern transects W–Y and AI showed slight pollution with values between 0.30 and 1.30 mg/liter. The remaining areas have TDS values within the background range ( 0.30 mg/liter) and thus show no evidence of pollution. Within this area, the TDS values of the northern transects were significantly higher than those of the southern transects. This difference was attributed to the difference in particle size of the intertidal sediments. The former transects were dominated by mud, whereas the latter transects were dominated by sand. This means that the relatively higher TDS values in the north were largely attributable to natural processes rather than human activities. It is believed that the occasional discharge of sewage
Figure 5. Spatial distribution of the total dissolved sulfide (TDS) in the interstitial water of the intertidal zone.
422
D. Al Bakri and W. Kittaneh
through the stormwater outfalls and the industrial and oil refinery effluents discharged to coastal water were the main sources of high TDS concentrations in the sites classified as polluted and slightly polluted. At Sulaibikhat Bay, where the highest TDS concentrations were recorded, the situation was further complicated by the presence of mud sediment and limited water circulation. These conditions are conducive to attracting and accumulating pollutants discharged through the outfalls or originated from natural processes.
Discussion
Figures 3 and 5 show a distinct correlation between the distribution of TOC and TDS values along the intertidal zone. The maximum concentrations of both parameters were recorded in Sulaibikhat Bay followed by the Kuwait City waterfront and Shuaiba Industrial Area coast. The organic and oil pollution evident in these sites was attributed to the occasional sewage discharge through stormwater outfalls, the direct oil spillage, and the industrial and refinery effluents at Shuwaikh Port and Shuaiba area. Comparing the results of this study with published data on the offshore area (Jacob and others 1982, Anderlini and others 1982, Abdul Razzaq and others 1982, Literathy and Salem 1986) revealed that salinity, TOC, and temperature in the summer were higher in the intertidal zone than in the subtidal area. In the winter temperature and pH were lower in the intertidal zone. These differences were attributed to the proximity of the intertidal zone to land-based sources of pollution, its exposure to air for long periods twice a day, and its higher level of biochemical processes. According to Al Bakri and others (1985), the benthic fauna community inhabiting the intertidal zone of Kuwait was considered impoverished and characterized by low diversity when compared with intertidal communities elsewhere. Large sections of the intertidal flats were inhabited by a single or a few species. The paucity of organisms has been attributed primarily to harsh environmental conditions, especially high temperature and salinity (Basson and others 1977, Clayton 1982, Jones 1982). Al Bakri and others (1997a,b) employed multivariate analysis and cluster analysis (SAS Institute 1982) to determine the interrelationships and interactions of the chemistry, sediments, and benthic fauna of the intertidal zone. Annual means of the chemical parameters were clustered by both the FASTCLUS procedure and the Bray-Curtise dissimilarity measure. Results from both procedures showed considerable regularity across all stations. The average chemistry of the stations was found to be similar, with a similarity
index of 0.814. Multivariate analysis of variance, canonical correlation, and canonical discriminant analysis have also shown that there was no significant correlation between the mean chemical parameters and the number of taxa and mean density of the benthic fauna. However, these analyses indicated that mud correlates moderately with water content, pH, TDS, and TOC. The quantitative analysis indicated that chemistry was not a determining factor in the overall distribution or composition of the intertidal organisms. However, qualitative examination of areas with maximum concentrations of TOC and TDS revealed that their fauna communities were showing sign of degradation in terms of taxa number and individual density when compared with areas of similar physical and sedimentological characteristics but relatively little pollution. Close qualitative examination of individual stations with abnormally high salinity and temperatures in the upper intertidal zone also revealed evidence of some impact on the number of taxa and abundance of some species. Based on the finding of this study and evidence from previous studies, it can be argued that the intertidal benthic community is dominated by a few tolerant species, which are probably living at the limit of their tolerance to harsh environmental conditions. It seems that the discharge of sewage, oil, and industrial effluents has a limited effect on the overall composition of the intertidal benthic fauna at the time of completing this survey. It should be borne in mind, however, that the lack of baseline data prior to this study does not allow for accurate identification of possible changes or deterioration in the ecosystem that might have occurred as a result of the intensive development activities since the 1960s. It is very likely that the discharge of untreated sewage and industrial wastes as well as oil spillage may lead, in the long term, to significant accumulation of pollutants and subsequently to serious damage to the coastal environment. It is recommended, therefore, that current disposal practices be controlled and closely monitored.
Conclusions
The exceptionally high salinity and temperature of the interstitial water and relative lack of hard substrates in the intertidal zone restricted the diversity of benthic fauna and led to the dominance of a few species probably living at the limit of their tolerance. These harsh environmental conditions made the intertidal ecosystem inherently fragile. Sections of the intertidal zone, mainly Sulaibikhat Bay and, to a lesser extent, the Kuwait City waterfront and Shuaiba coast in the south, were showing evidence of sewage and oil pollution. This
Kuwaiti Intertidal Zone Pollution Indicators
423
pollution was primarily attributed to land-based sources such as the occasional discharge of sewage through the stormwater outfalls, industrial effluents, and oil spillage from exporting oil terminals and refineries. Although statistical analysis indicated that the relatively high TOC and TDS were not detrimental to the overall composition of benthic fauna, close examination of the situation provided evidence that the intertidal ecosystem in those areas was under stress. Continuing anthropogenic discharge will certainly lead, in the long term, to irreversible damage to this fragile ecosystem. It is recommended that environmental policies must be stringently applied to stop these highly undesirable and harmful disposal practices. Furthermore, the discharges of stormwater outfalls and industrial effluents as well as the intertidal ecosystems in sites showing high TOC and TDS concentrations should be closely monitored and assessed to ensure that the situation will not deteriorate any further. Results of this study are of particular value for future monitoring and assessment of coastal pollution and other environmental hazards. Studies to assess trace metals and trace organics in the coastal zone should focus on sites that show high concentrations of TOC and TDS. This article, together with those of Al Bakri (1996) and Al Bakri and others (1997a,b) provide a comprehensive assessment of the physical, chemical, and biological aspects of the intertidal zone of Kuwait and thus establish a very useful benchmark for evaluating the long-term environmental impact on this sensitive ecosystem, particularly those impacts caused by the Gulf War. It is also recommended that the findings of these studies be integrated into the coastal management process to ensure protection of the coastal environment and development of a sustainable coastal management system.
Al-Awadi, F., M. Ghaleb, G. Mehdirata, D. Al Bakri, and others. 1988. Environmental protection standards and guidelines for the State of Kuwait: Ambient sea water quality standards. Environment Protection Council, Kuwait, 165 pp. Al Bakri, D. 1994. A geomorphic framework for developing a sustainable greenery program in arid environment. The Environmentalist 14(4):271–282. Al Bakri, D. 1996. A geomorphological approach to sustainable planning and management of the coastal zone of Kuwait. Geomorphology 17:323–337. Al Bakri, D., M. Foda, M. Behbehani, F. Khalaf, W. Shublaq, and A. Khuraibet. 1985. Environmental assessment of the intertidal zone of Kuwait. Research report, volumes 1 and 2. KISR 1687. Kuwait Institute for Scientific Research, Kuwait, 429 pp. Al Bakri, D., A. Khuraibet, and M. Behbehani. 1997a. Quantitative assessment of the intertidal environment of Kuwait—I: Integrated environmental classification. Journal of Environmental Management (in press). Al Bakri, D., M. Behbehani, and A. Khuraibet. 1997b. Quantitative assessment of the intertidal environment of Kuwait— II: Controlling factors. Journal of Environmental Management (in press). Al-Harmi, L., and V. Anderlini. 1980. A survey of tar pollution on beaches of Kuwait. Annual research report, 1979. Kuwait Institute for Scientific Research, pp 82–85. Al-Mossawi, M., W. Awadh, and M. Salama. 1980. Incidence of antibiotic resistant fecal coliform bacteria in Kuwait coastal waters. Annual research report, 1979. Kuwait Institute for Scientific Research, pp 85–87. Anderlini, V. C., P. Jacob, and J. Lee. 1982. Atlas of physical and chemical oceanographic characteristics of Kuwait Bay. KISR 704. Kuwait Institute for Scientific Research, Kuwait. Basson, P. W., J. E. Burchard, J. T. Hardy, and A. R. Price. 1977. Biotopes of the western Arabian Gulf: Marine life and environments of Saudi Arabia. Arabian American Oil Co., Dhahran, Saudi Arabia. Behbehani, M. 1983. Oil pollution in the ROPME sea area with special reference to recent incidence. A paper presented at Mabahiss—John Murray international symposium of marine science of the northwest Indian Ocean and adjacent water, 3–6 September, Alexandria, Egypt. Clayton, D. A. 1982. Ecology of mudflats with particular reference to those of the north Arabian Gulf. The first conference on environment and pollution, Kuwait, 7–9 February 1982. Cooke, R. U., A. Warren, and A. Goudie. 1993. Desert geomorphology. UCL press, London. Davis, R. A. 1977. Principles of oceanography, 2nd ed. AddisonWesley Publishing, New York. EPC/SAA. 1980. Salinity in Doha and Shuwaikh from 1979 to 1980. Environment Protection Centre, Shuaiba Area Authority, Kuwait. EPC/SAA. 1983. Code of industrial services at Shuaiba Industrial area—code of practice and environmental guidelines. Environment Protection Centre, Shuaiba Area Authority, Kuwait. EPC/SAA. 1985. Annual reports 1984–1985. Environment Protection Centre, Shuaiba Area Authority, Kuwait.
ACKNOWLEDGMENTS
This article is based on data obtained from a research project funded by the Environment Protection Council of Kuwait and carried out at the Kuwait Institute for Scientific Research. Special thanks are extended to the team members of project EES-35 for their valuable contributions throughout the study. Thanks are also extended to Mrs. Liz Greer for preparation of Figures 3 and 5.
Literature Cited
Abdul Razzaq, S., F. Khalaf, D. Al Bakri, and others. 1982. Marine sedimentology and benthic ecology of Kuwait marine environment. KISR 694. Kuwait Institute for Scientific Research, Kuwait.
424
D. Al Bakri and W. Kittaneh
EPC/SAA. 1986. Assessment of sulfide in sea water, February— March 1986 and Shuaiba refinery outlet, April 1985— March 1986. Environment Protection Centre, Shuaiba Area Authority, Kuwait. EPD. 1984. Annual report 1984. Environment Protection Department, Ministry of Public Health, Kuwait. EPD. 1987. Annual reports 1985–1987. Environment Protection Department, Ministry of Public Health, Kuwait. Forstner, U. 1977. Metal concentration in fresh water sediments, natural background and cultural effects, Pages 94– 103 in H. L. Golterman (ed.), Interactions between sediments and fresh water. The Hague. Jacob, P., M. Zarba, and O. Mohammad. 1982. Water quality characteristics of selected beaches of Kuwait. Indian Journal of Marine Science 11:233–238. Jones, D. 1982. Ecology of the rocky and sandy shores of Kuwait. First conference on environment and pollution, 7–9 February, Kuwait. Karichkhoff, S. W., D. S. Brown, and T. A. Scot. 1979. Sorption of hydrophobic pollutants. Water Research 13:241–248. Khalaf, F., P. Literathy, D. Al Bakri, and A. Al-Ghadban. 1986. Total organic carbon in the marine bottom sediments off Kuwait, Pages 117–126 in D. Halwagy, D. Clayton, and M. Behbehani (eds.), Marine environment and pollution of the Arabian Gulf. Kuwait University, Kuwait. Khordagui, H. 1991. Comments on current environmental events in Kuwait. Environmental Management 15(4):455–459. Khordagui, H., and D. Al-Ajmi. 1993. Environmental impact of the Gulf War: An integrated preliminary assessment. Environmental Management 17(4):557–562. KISR. 1981. Oceanographic monitoring program in Shuaiba offshore area. Kuwait Institute for Scientific Research, Kuwait. Lambert, S. M. 1968. Omega, a useful index of soil sorption equilibria. Journal of Agricultural Food Chemistry 16(2):340– 343. Lee, J. W. 1983. Oceanographic characteristics of Kuwait waters in 1981. Pages 11–16 in Proceeding of third shrimp
and fine fisheries management workshop, 4–5 December 1981. Kuwait Institute for Scientific Research, Kuwait. Literathy, P., and A. Salem. 1983. Effects of pollutants on water quality: Fish kills. KISR 2355. Kuwait Institute of Scientific Research, Kuwait. Readman, J. W., S. W. Fowler, J. P. Villeneuve, C. Cattini, B. Oregioni, and L. D. Mee. 1992. Oil and combustion-product contamination of the Gulf marine environment following the war. Nature 358:662–665. ROPME. 1983. Manual of oceanographic observations and pollutant analyses methods. Regional Organisation for the Protection of Marine Environment, Al-Safat, Kuwait. ROPME, IOC (UNESCO), UNEP, NOAA, EPC. 1993. Final report of the scientific workshop on the results of the R/V Mt. Mitchell cruise in the ROPME sea area, vol. 1. Regional Organisation for the Protection of Marine Environment, 24–28 January 1993, Kuwait. Saenger, P. 1994. Cleaning up of the Arabian Gulf: Aftermath of an oil spill. Search 25(1):19–22. Samhan, O., V. Anderlini, and M. Zarbra. 1980. Preliminary investigation of the trace metal levels in the sediments of Kuwait. Pages 93– 96. Annual research report, 1979. Kuwait Institute for Scientific research, Kuwait. SAS Institute. 1982. SAS user’s guide: Statistics, 1982. SAS Institute Inc., Cary, North Carolina. Thomas, S. M., and J. M. Jacquet. 1976. Mercury in the surficial sediments of Lake Erie. Journal of the Fishery Research Board of Canada 33:404–412. USEPA. 1979. Methods of chemical analysis of water and wastes. Report No. 600/4-79-020. US Environmental Protection Agency, Washington, DC. USEPA. 1986. Quality criteria for water—1986. US Environmental Protection Agency, Washington DC. Zarba, M., V. Anderlini, L. Literathy, and F. Shunbo. 1983. Distribution of petroleum hydrocarbons in marine sediments of Kuwait. Pages 150–152. Annual research report, 1982. Kuwait Institute for Scientific Research, Kuwait.
