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ISSN 1811-0231 / ISEIS Publication Series Number P002

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  Paper EIA06-017, Volume 4 (2006), Pages 209-217 = complimentary

Pollution of the Caspian Sea Marine Environment Along the Iranian Coast

A. Parizanganeh1, V. C. Lakhan2* and S. R. Ahmad2

1. Department of Geography, Zanjan University, PO Box 45195-313, Zanjan, Iran.

2. Department of Earth Sciences, University of Windsor, Windsor, Ontario, Canada N9B 3P4. *Corresponding author: lakan@uwindsor.ca.

 

Abstract

The nearshore marine environment of the Caspian Sea is a major repository for toxic metals originating from various natural and anthropogenic sources. The metals are not easily degraded or destroyed, and tend to accumulate in coastal soils and sediments. Since the persistent toxic metals pose serious health risks this research concentrated on investigating the concentrations and spatial distribution of metals in the nearshore sediments along the Iranian coast of the Caspian Sea.
Fourteen sampling sites, approximately 50 km apart, were selected from the nearly 700 km long Iranian coast. A standard Van Veen grab was used to obtain approximately 400 g of surficial sediments. To interpret the effects of grain size on metal concentrations, each of the 14 samples was sieved. Selection of three grain size fractions (0.355 mm, 0.212 mm, and 0.075 mm) from each sample plus fourteen bulk samples yielded a total of 56 samples for the analysis of metals. Each of the 56 samples was analyzed for the presence of 18 metals, these being Al, As, Bi, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sb, V, and Zn. Laboratory analysis of the samples utilized the Cold Acetic protocol, followed by Inductively Coupled Plasma Optical Emission Spectroscopy.
Box and Whisker plots revealed differences in the contaminant levels of each of the samples. There were large spatial variations in the median concentrations of the heavy metals (Al, Cd, Cu, Pb, Ni, and Zn) at the various sampling sites. Concentrations exceeded recommended guidelines in several areas especially in the vicinity of the Azerbaijan and Turkmenistan borders. Linear regression analysis demonstrated that grain size of the sediments was not a major factor controlling the concentrations and spatial distributions of the heavy metals. The concentrations of heavy metals in the medium and coarse sediment fractions reflected loadings from anthropogenic sources located at, and in the vicinity of the sampling sites. In addition, the presence of heavy minerals or coarse fractions of terrigenous origin also contributed to the increase of metal concentrations in the medium and coarse sediment fractions. Since silt and clay fractions were negligible in the sieved sediments, the claim could be made from the findings of this research that it is necessary to consider all sediment sizes to understand loadings and concentrations of metal contaminants in the marine environment.


Keywords: Caspian Sea, discriminant analysis, heavy metals, Iran, marine environment, nearshore sediments

 

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