Geochemical Indicators of Organo-Chloro Pesticides in Lake Sediments

Abstract

The study area, Lake Liangzi is regarded as one of the least polluted lakes in Central China. This is because the local people have made great efforts to protect the lake from the use of all forms of chemicals for crop and fish farming activities. Besides this measure, other uses such as recreation, water supply and electricity production are also not permitted. In fact, it is noteworthy to mention that the lake supplies one of the most popular and delicious types of fish in Central China. It is called “Wuchang fish” and is very popular in most leading restaurants in Central China and quite expensive for its delicacy. However, since modern technology has revealed that organic compounds such as Organo chloro-pesticides (OCPs) could be deposited into lakes and other water bodies from remote areas, far from the point of application, it will be worthwhile to undertake investigation to ascertain whether the lake is free from these contaminants. The path of investigation used dated sediment core since according to Venkatesan, et al, (1998), the history of chlorinated hydrocarbon contamination can be followed using contaminants from dated sediment cores, since sediments integrate and retain records of influx of recalcitrant organic contaminants. It should be mentioned that this volume of work is part of the author’s PhD research and also one of the pioneering research works on pesticides in the lake. OCPs are a group of common pollutants belonging to the class of pollutants called Persistent Organic Pollutants (POPs). One of the most important families of Persistent Organic Pollutants (POPs) that has a significant impact upon the environment are pesticides. According to Sierra Club of Canada, (1998), pesticides are the only man-made toxic chemicals deliberately released over large areas. They are poisonous almost by definition. Pesticides poison the food chain, contaminate water supplies and are implicated in the declining populations of many biotic species. In this study, a single drilled undisturbed sedimentary core extracted from Lake Liangzi in Central China was analyzed for target compounds using highly sophisticated instruments. Even though other organic compounds (such as Polycyclic Hydrocarbons; PAHs, Aliphatic Hydrocarbons; Ahs and heavy metals) were detected, they are not discussed in this article.. The focus of discussion are the organocgloro-pesticides, including DDT, DDD and DDE and the geochemical relationship between them.