RESPONSE OF FISH TO METAL POLLUTION ALONG THE EGYPTIAN COAST

Abstract

In natural aquatic ecosystems, metals occur m low concentrations, nonnally at the nanogram to microgram per litre level. In recent times, however, the occurrence of metal contaminants, especially the heavy metals in excess of natural loads, has become a problem of increasing concern. This situation has arisen as a result of the rapid growth of population, increasing urbanization., expansion of industrial activities, exploration and exploitation of natural resources, extension of irrigation and other modem agriculture practice as well as the lack of environment regulation.

Trace metals enter the aquatic environment from both natural (geochemical background) and anthropogenic sources. Entry may be as a result of direct discharges into both freshwater and marine ecosystems or through indirect routes such as dry and wet deposition and land runoff. In view of the toxic nature of the trace heavy metals, the knowledge of their sources and fate in the environment is important. The anthropogenic sources of metals include; mining, industrial and petroleum industry activities, domestic eflluents and urban storm-water runoff, leaching of metals from garbage and solid wastes dump, metal inputs from rural areas, e.g. metals contained pesticides and atmospheric sources, e.g. burning of fossil fuels, incineration of wastes and industrial emission. Different examples of potential industrial and agricultural sources for metals in the environment have been reported by FAO (1992).

This report also shows that for most trace metals, anthropogenic emissions are either more than or quite equal to natural emissions. The combustion of leaded petrol in automobiles, for instance, is responsible