Persistent organochlorine compounds in water and soil environments

Reviews compound physicochemical properties and water and soil properties influencing the transport and distribution of organochlorine pesticides, polychlorinated biphenyls (PCBs) and chlorophenols in a water and soil environment. As highly hydrophobic compounds of low water solubility, organochlorine pesticides and PCBs are rapidly and strongly sorbed by most soils and sediments. The sorption of weakly acidic chlorophenols comprises both molecular and ionic forms and depends not only on the soil/sediment organic matter content but also on the pH and ionic strength of the aqueous phase. Briefly describes the analytical methods for trace analysis of organochlorine pesticides, PCBs and chlorophenols in water and soil/sediment samples. Presents some results of those micropollutants’ analysis in surface, ground and drinking waters, soils, river sediments and wet depositions in Croatia. Persistent and toxic organochlorine (OC) pesticides, polychlorinated biphenyls (PCBs) and chlorophenols (CPs) belong to the micropollutants of water and soil environments distributed worldwide. The use of OC pesticides has been restricted or banned in most developed countries but continues in developing countries. PCBs are a group of 209 congeners which have been widely used as heat transfer fluids, hydraulic fluids, flame retardants and dielectric fluids. For their easier handling a systematic numbering has been introduced and widely accepted as PCB numbers[1]. In developing countries PCBs have been substituted only partially. CPs, particularly those with three and more chlorine atoms have been used as fungicides with main applications in the preservation of wood, leather and textiles as well in pulp and paper industries. They are also intermediates in the production of phenoxy herbicides and degradation products of hexachlorocyclohexane and chlorobenzenes. CPs can also be formed by routine disinfection of drinking water by chlorination as a result of chlorination of phenols and as by-products of the reaction of hypochlorite with phenolic acids. OC pesticides, PCBs and CPs enter the environment either directly, mostly through the pesticides application and uncontrolled waste discharge, or indirectly through atmospheric transport. Their levels and distribution in the environment need to be controlled by means of an environmental risk assessment. PCBs are considered to be the main precursors of highly toxic polychlorinated dibenzo-pdioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). PCDD and PCDF traces are contained also in technical tri-, tetraand pentachlorophenol formulations. In this paper some factors influencing the behaviour of persistent and lipophilic OC compounds in water and soil environments and the analytical methods for analysis of OC pesticides, PCBs and CPs in aqueous and soil/sediment samples are briefly described. The environmental levels of those pollutants are illustrated by selected results of OC pesticides, PCBs and CPs analysis in different waters, soils, river sediments and wet depositions in Croatia. Factors affecting transport and distribution of PCBs, OC pesticides and CPs in water and soil environments