الفهرس 
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Abstract
1.1. Definition:
Pollution occurs when a substance, an organism, or energy (e.g., sound or heat) is
released into the environment by human activities and produces an adverse effect on
organisms or the environmental processes on which they depend. Some pollutants in
sufficient concentrations are toxic to organisms in marine environment. These include both
naturally and occurring chemicals present in much higher concentrations as a result of human
activities (e.g., trace metals and oil) as well as compounds that did not exist in nature until
manufactured by humans (e.g., pesticides such as DDT). Toxic pollutants, including
pesticides, industrial organic chemicals and trace metals are widespread contaminants of the
marine environment. Some of these chemicals are known through experimental studies to
affect the reproductive, immune, or endocrine systems of marine organisms at low
concentrations, and may have subtle effects on marine organisms and populations over a
broader area. While some of the most toxic substances have been banned for manufacture and
use, material previously released may remain in the environment for decades to centuries (1).
1.2 Heavy Metals:
Heavy metals which are considered as one of the most important pollutants are capable of
spreading in different compartments such as in sediments of marine environment and
circulating between them depending on sediment texture, mineralogical composition,
reduction/oxidation state, adsorption/desorption processes and physical transport.
As a result of anthropogenic activity, the input of heavy metals to the marine environment
has increased sufficiently and resulted an increase in their concentrations in water, sediments
and tissues of living organisms through bio-accumulation and bio-magnification processes (2).
This can mainly occurs through three main ways:
i) direct discharge of effiuents and solid wastes into the seas and oceans (industrial
discharge, municipal waste discharge, coastal sewage, and others);
ii) land runoff into the coastal zone, mainly with rivers;
ill) atmospheric fallout of pollutants transferred by the air mass onto the seas’ surface.
1.3 Organometallic Compounds (OMCs):
Organometallic compounds, on the other hand, are formed when a group of compounds
containing in their molecules at least one metal atom are bonded to an atom of carbon of an
organic functional group (3). These compounds are characterized by their different
physicochemical properties, which depend both on the kind of metal and the organic groups
bonded to it. Many organometallic compounds are solid, others are liquid and some exhibit a
substantial volatility and occur as gases (4). However, organometallic forms of metals are
usually much more toxic than their inorganic counterparts. Some organometallic forms of
mercury, arsenic and now tin have been observed to have efficient biocidal properties, and
that different compounds of the same or different metals may coexist at the same location in
the environment (5).