Quality of Surface Waters (Chemistry) 1991
Pollutant Impacts in Sediments and Eels: Introduction
Industrial development has enormously increased discharges of pollutants into waters. Besides their presence in water, there is a continual accumulation of pollutants in water bottom soils, such as heavy metals and chlorinated hydrocarbons.
Deposition in Sediments
Sediments form a natural buffer and filter system in the material cycles of waters. Waters are subject to strong variations of current, substance input and transport, and sedimentation. Diverse inputs of the Berlin metropolitan area, including domestic and industrial waste waters, and rainwater, flow through the urban waterways primarily into the Lower Havel. The lake-like enlarged areas of the Lower Havel, with their low flow velocity, offer ideal conditions for the settling out (sedimentation) of pollutants floating in the water onto the water bottom.
Sediment analysis is increasingly important in evaluating qualities of the total ecosystem of a body of water, in addition to the water sample analysis practiced for years.
In comparison to water testing, sediment testing reflects the long-term quality situation independent of current inputs. Sediment tests are a better basis for fundamental comparisons with other flowing waters. In water testing it is not possible to clearly divide between true suspension substances and temporary suspension substances stirred-up from the sediments. Sediment testing is not, or only minimally, affected by other influences.
The suspension and precipitate (non-floating) mineral and organic substances in waters are capable of adhering pollutant particles (adsorption). The sediments, both suspended and precipitate substances stored on the water bottom, form a reservoir for many pollutants and trace substances of low solubility and low degree of degradability.
(Pollutant) Substances are conserved in sediments over longer periods of time according to their chemical persistence and the physical-chemical and biochemical characteristics of the substrata. Analysis of sediment samples from different depths give a chronological record of inputs in waters. This can also allow conclusions to be drawn regarding sources of contamination.
Even after sedimentation, portions of fixed substances can be remobilized and reenter the material cycle of waters. Causes for this include desorption, liberation after mineralization by organic material, whirling up, weathering, and the physical and physiological activity of benthonic (water bottom) organisms.
Heavy metals can enter waters naturally in erosion and wash-out processes. By discharge from the effluent inflows mentioned above, amounts of heavy metals in waters are steadily increased. They are present in waters in dissolved form only at low levels, since heavy metal compounds are of low solubility. Mineral suspension and precipitation substances are able to store heavy metal ions on their outer surface. They can also be bound in water organisms. Heavy metals can be taken up by higher organisms through the food chain, or sink to the bottom as sediment, depending on the flow velocity of waters.
Some heavy metals are necessary for life in tiny amounts, such as the trace elements copper, zinc, manganese. But in higher concentrations they damage humans, animals and plants just like the highly-toxic heavy metals such as lead and cadmium.
The heavy metals most often present at high measured values in Berlin waters will now be discussed.
Copper is a semi-precious metal and often used in the electrical industry. The toxic effects of copper compounds are applied as algaecides and fungicides. Copper is toxic even in low amounts for all water organisms, such as bacteria, algae, fish prey and fish. Copper can have negative effects on the population and self-cleansing of waters. Copper is significant as the most important trace element for human metabolism. But high concentrations damage health, although usually only temporarily and not chronically.
Zinc, like copper, is an element important for human life. Zinc is often used in the manufacture and surface treatment of pipes and tin-cans. Like copper, high zinc concentrations have toxic effects on water organisms. Zinc accumulates particularly in mollusks such as snails and mussels.
Lead, next to cadmium and mercury, is one of the most toxic heavy metals. It is not essential for human metabolism. Lead compounds are used in the manufacture of paints, anticorrosion additives and batteries. Waterpipes of lead are sometimes found in old buildings. The largest lead emitter is still automobile traffic, in spite of reduced use of leaded gasoline. The continual ingestion of lead can lead to severe damage of the nervous system and the deactivation of various enzymes.
Cadmium is employed in battery production, as a stabilizer in PVC production, as pigment in plastics and lacquers, and in galvanizing. The toxic effects of cadmium at extremely low levels are recognized. Cadmium accumulates especially in the liver, kidneys, spleen and thyroid glands, and can lead to severe damage of these organs.
Pesticides, PCB and their Absorption by Eels
Chlorinated Hydrocarbons – CHC (=CKW) have bonded chlorine onto the shells of their carbon atoms. In the group of halogenated hydrocarbons, CHCs find the most frequent manufacture, application and dispersal.
Chlorinated hydrocarbons are numerous and have diverse compounds. Many organic chlorine compounds are very persistent, such as DDT and polychlorinated biphenyls, PCB.
Many compounds of chlorinated hydrocarbons are water-soluble. Others, such as DDT and PCB are fat-soluble and accumulate in fatty tissues of organisms. Various pesticides and PCB have the characteristic of being stored adsorptively on suspended matter or in plant organisms, especially with declining water solubility. Waters with weak currents suspended substances to sink. These substances are deposited with their pollutants in the sediment. Sediment organisms are an important nutrient basis for fish. Fish inhabiting the bottom (benthonic fish) are especially likely to take-up high contaminant concentrations in their fatty tissues. Eels become very fat, eat bottom organisms and bury themselves in sediment. This behavior leads to the intake of pesticides and PCB not only through nutrients but through the skin as well, and to their storage in body fat.
DDT, dichlorine diphenyl trichlorethane is a highly stable chlorinated hydrocarbon of extremely low degradability. DDT is one of the most well-known pesticides and was previously used world-wide. The fat-solubility and extreme-persistence of DDT have led to its storage in the body fats of almost all organisms. The global use of DDT has had an impact on the entire environment. The use of DDT has been made illegal by almost all countries. DDT is mutagenic (DNA damaging) and is suspected of being carcinogenic.
Lindane is mainly used as a contact and nutrient poison for pest control of ground insects and on harvested seed crops. Lindane is not evaporative at temperatures up to 30° C and has a low chronically toxicity -but is acutely toxic. Poisoning symptoms in humans are nausea, headache, vomiting, cramping, breathing difficulties. It can damage the liver and kidneys. Lindane also possesses a high toxicity for fish, but it is relatively quickly excreted by the body and degraded.
PCBs, polychlorinated biphenyls. These chlorinated hydrocarbons are among the most stable chemical compounds and of low degradability. Their good isolation characteristics and low combustibility led to their use in condensers and high-tension transformers. Other uses of PCBs are in lubrication, impregnation, and flame-retardant materials. The main causes of PCB inputs into Berlin waters are automobile traffic, rainwater contaminated by automobiles, as well as automobile and scrap disposal.
PCB in high concentrations causes liver, spleen and kidney damage. Severe poisonings cause organ damage and cancer.
Some PCB manufacturers, handlers and applications have been subject to legal restrictions on its manufacture and use since 1989 (PCB-, PCT-, VC-Verbotsverordnung of 18 July 1989).
High values have been verified in Berlin waters and sediments. Tests conducted in the 80’s on fish found CHCs such as PCB and the pesticides DDT and Lindane in concentrations extremely disturbing for foodstuffs.
High amounts of CHCs led to a marketing ban forbidding the sale of fish from Berlin waters after the Pollution Maximum Amount Regulations (SHmV of 23 March 1988) took effect. Fish caught after the issuance of this prohibition were disposed of as hazardous waste. The association of commercial fisheries, in commission of the Berlin Office of Fisheries, conducted a fishing program to effect a reduction of pollutant impacts in Berlin fish stocks by means of a specific influencing of the age structures of fish stocks. The intensive fishing of older fish was aimed at achieving a stock of younger fish, low in fat and thus low in lipophillic (fat-loving) CHCs like PCB, DDT and Lindane, etc. As a result of sharper permit procedures for potential polluters, and ‘rejuvenated’ fish stocks, the prohibition against marketing of fish was lifted in May, 1992.