Several pollutants such as HCB, DDT and lindane were investigated during the 2001 survey. Generally, concentrations were low, except that of DDT and its compounds which exceeded NOAA quality standards at a number of locations in Azerbaijan and Iran. The Kura River was identified as a main source of such contamination (Mora and Sheikholeslami 2002). Furthermore, according to the same survey, lindane concentrations exceeded the Canadian (ISQG) sediment quality guideline value in the Russian sector, with concentrations of 609 pg/g compared with the quality guideline standard of 320 pg/g. Five years later, no significant changes in DDT concentration were recorded: at some sites in Azerbaijan and Iran, concentrations were still high – three times above the ISQG standard. A persisting problem due to the use of DDT was observed in the Volga Delta, Azerbaijan and Iran, despite the global ban. Nickel (Ni) was observed in high concentrations and exceeded the NOAA value of 21 µg/g in all the countries of the Caspian Sea, particularly in Azerbaijan and Iran where all monitored sites exceeded the standard level. The highest concentrations were found near the mouth of the Kura River, and it is clear that the Ural River also has an impact on concentration levels. These generally high levels reflect a predominantly natural nickel presence, but this could be augmented by mining activities. Chromium (Cr) concentrations exceeded the NOAA value of 81 µg/g at almost all the locations in Azerbaijan and Iran, and at some sites in Kazakhstan. The Caspian Sea region is mineral-rich and several countries, most notably Kazakhstan, are important producers of chromium. The high concentrations of Cr stem from its natural presence in the region.
From collection: Caspian Sea - State of Environment 2011