POLLUTION OF MARINE WATERS

This chapter summarizes the major environmental sources of marine water pollution in the Asian region, marine water chemistry and its changes under an increasing pollution load. We will discuss also the consequences of seawater pollution to various coastal and marine ecosystems in Asia. 

SOLUBLE AND SOLID DISCHARGE OF POLLUTANTS INTO THE PACMC AND INDIAN OCEANS 

It is notable that over 75% of the pollution entering the Pacific and Indian oceans word-wide comes from human activities on land (Eigure 1). 

Most nutrients, sediments, pathogens, persistent toxicants and thermal pollution come from land based sources, through rivers, direct discharge or airborne emissions. Even oil pollution, which is typically associated with tanker operations and accidents at sea, actually comes as much from land as from the sea. Coastal waters in particular, which are less mixed than areas farther from the shore, are under increasing pressure from environmental pollution. 

The river waters in the Asian region are often heavily contaminated by municipal sewage, industrial effluent and sediments, which form the most important sources of pollution. Of the estimated total of 13.5 x 10 tons per year of sediment transported by the World s rivers, Asian rivers accounted for nearly 50%, although they constitute only 17% of the World s total drainage area. Basically, this is the result of lack of sanitation, discharge of untreated industrial effluents into the rivers, and sediment 

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POLLUTION OF MARINE WATERS Table 2. Complexation of species in seawater. 

Atmospheric contaminants from smelting works or combustion processes eventually enter the natural drainage system as fall out, and are carried into the rivers. It is probable that the deposition of sediments and the higher pH of marine water, which leads to precipitation, results in a build-up of the heavy metal pollutants in the river estuary. An assessment of this build-up is essentially an analytical problem. 

Meyer-Reil L. and Koster M. (2000) Eutrophication of marine waters effects of benthic microbial communities. Mar. Pollut. Bull. 41, 255-263. 

In the middle and low reaches of the Pearl River, fertilizer was widely used in agriculture, and this was also a main source of nutrients for the estuary. This kind of non-point pollution of surface water was also one of the main sources of nutrients in other countries. There was a lot of marine culture in the PRE. The surplus feedstuff and the excretion of fish also contributed much to nutrients. 

The most common pollutants of surface waters and groundwater on land are bacteria and other organic matter, hydrocarbons, industrial waste, pesticides and other agrochemicals, and household products. Efforts to limit water pollution centre on the treatment of urban and industrial wastewaters, and unchannelled inflows, such as those of agricultural origin, are more difficult to control. Mention must also be made of marine pollution, oil spills in particular. 

The nature of marine pollution requires that it be regulated internationally, since once a pollutant enters marine waters, it knows no boundary. Thus, a series of regional treaties and conventions pertaining to local marine pollution problems and more comprehensive international conventions providing uniform standards to control worldwide marine pollution have evolved over the last 25 years. 

Zhou F, Guo H, Liu Y, Jiang Y (2007) Chemometrics data analysis of marine water quality and source identification in Southern Hong Kong. Mar Pollut Bull 54 745-756... 

Quantitative analytical methods using FIA have been developed for cationic, anionic, and molecular pollutants in wastewater, fresh waters, groundwaters, and marine waters, several examples of which were described in the previous section. Table 13.2 provides a partial listing of other analytes that have been determined using FIA, many of which are modifications of conventional standard spectropho-tometric and potentiometric methods. An additional advantage of FIA for environmental analysis is its ability to provide for the continuous, in situ monitoring of pollutants in the field. ... 

As indicated above, national policies and international conventions have been invoked to curb known, and usually obvious, sources of marine pollution. National legislation is used to control coastal discharges of contaminants. A major problem remains owing to the inadequate treatment of sewage prior to emission from land-based sources. The most important deleterious effects in this case are with respect to microbial water quality. This can have a direct influence on bathing criteria and result in beach closures during contamination episodes. An additional problem from land-based sources pertains to transboundary effects, whereby pollution may inadvertently be exported from one country to another. 

Consultants are equipped to monitor the quality of freshwater, estuarine and marine environments and can make field measurements of a variety of water-quality parameters in response to pollution incidents. For example, reasons for the mortality of marine shellfish and farmed freshwater fish have been determined using portable water-analysis equipment. Various items of field equipment are, of course, also employed in baseline studies and monitoring, respectively, before and after the introduction of new effluent-disposal schemes. 

Apart from release into air, which is important globally, the direct transfer of PAH to water or land surfaces can be very important locally. Wreckages of oil tankers and discharges from oil terminals cause marine pollution by crude oil, which contains appreciable quantities of PAH. Disposal of waste containing PAH around industrial premises has caused serious pollution of land in some localities. 

Varanasi, U., Stein, J.E., and Reichert, W.L. et al. (1992). Chlorinated and aromatic hydrocarbons in bottom sediments, fish and marine mammals in US coastal waters laboratory and field studies of metabolism and accumulation. In C.H. Walker and D.R. Livingstone (Eds.) Persistent Pollutants in Marine Ecosystems, Oxford, U.K. Pergamon Press, 83-118. 

RoUhus KR, Fitzgerald WF. 1995. Linkages between atmospheric mercrrry deposition and the methyhnercury content of marine fish. Water Air Soil Pollut 80 291-297. 

Lee, R.F., Ryan, C. (1979) Microbial degradation of organochlorine compounds in estuarine waters and sediments. In Proceedings of the Workshop of Microbial Degradation of Pollutants in Marine Environments. EPA-600/9-79-012. Washington, D.C. 

Comparing the six sampling points monitored in this study (Fig. 4), HEIMD followed by HDAD were the most polluted ones, showing concentration levels of total pesticides above 5 pg/L in 39% and 22% of the samples analyzed, respectively. As expected, the sampling points located in the two bays (HEM and HDM) were the less polluted, due to the dilution effect of the marine water. This dilution effect may explain also the higher contamination level observed in the northern bay as compared to the southern bay, which is comparatively larger in size and depth. 

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