Heavy metal pollution in aquatic environments
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Tarih
2011
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Nova Science Publishers, Inc.
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
Metals which in their standard state have a specific gravity (density) of more than about 5 g cm-3 are described as 'heavy metals'. Some of them, such as copper, iron, chromium, zinc and nickel are essential in very low concentrations for the survival of all forms of life. These are described as essential trace elements. Only when present in greater quantities, these can cause metabolic anomalies like the heavy metals lead, cadmium, arsenic and mercury which are already toxic in very low concentrations. Heavy metals are produced from a variety of natural and anthropogenic sources. Human beings release a high anthropogenic emission of heavy metals into the biosphere. Waste (i.e. emission, wastewater and waste solid) is the origin of heavy metal pollution to water, soil and plants. In aquatic environments, metal pollution can arise from direct atmospheric deposition, geological weathering or through discharge of agricultural, municipal, residential or industrial waste. Under certain environmental conditions, heavy metals may accumulate to a level of toxic concentration causing ecological damage. As a result, living things inhabited contaminated waters may show rather high metal concentrations. In addition, metal bioaccumulation causes biochemical or pathological effects on fish resulting in decrease of growth, fecundity and survival. The members from the upper level of the food chain may carry a critical level of metals and are hence more explanatory than observing water or sediments. Therefore, numerous reports describe metal residues in aquatic organisms such as mussels, shrimp and wild fish from marine and freshwater species. Such studies have been carried out to determine the levels of some heavy metals in some tissues of aquatic organisms from marine and inland waters. Liver, spleen and kidney tissues are known to have high metabolic activities and thus have been used to observe the level of absorbed metals. Gonads, which can be attributed to the reproductive cycle of fish, have also accumulated high amounts of heavy metals. Metal concentrations in the skin and gills have reflected the concentration of metals in waters. Although it is well known that muscle is not an active tissue in accumulating heavy metals, muscle tissue accumulation levels were also studied because of their consumption by humans. Metal uptake by aquatic organisms from contaminated water may differ depending on its ecological needs and metabolism, as well as other factors such as salinity, temperature, contamination gradients of water, food, sediment and interacting agents. Two main objectives prevail in aquatic pollution monitoring programs: (1) determining contaminant concentrations in consumed part of organisms considering the health risk for humans, and (2) using organisms as an environmental indicator of aquatic ecosystem's quality. © 2010 Nova Science Publishers, Inc. All rights reserved.
Açıklama
Anahtar Kelimeler
Kaynak
Impact, Monitoring and Management of Environmental Pollution
WoS Q Değeri
Scopus Q Değeri
N/A
