Analysis of polychlorinated biphenyls, organochlorine pesticides and chlorophenols in rain and snow

Abstract

Polychlorinated biphenyls (PCBs), organochlorine pesticides and chlorophenols were measured in samples of rain and snow collected at urban and suburban/semi-rural locations in the Zagreb City area, Croatia. PCBs and organochlorine pesticides were extracted with hexane from filtered aqueous samples and from particulate matter isolated by filtration. Chlorophenols were accumulated from rain and snow water by C₁₈ reversed-phase adsorption. All samples were analysed by capillary gas chromatography using an electron-capture detector. Polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDFs) in rain and snow water were checked by gas chromatographic–mass spectrometric analysis of combined hexane extracts. PCBs were detected in all water (<1–203 ng l^–1) and particle (40–4155 ng g^–1) samples. The only organochlorine pesticide present in all rain and snow water (1–36 ng l^–1) and in particle (7–512 ng g^–1) samples was γ-hexachlorocyclohexane as a consequence of the regular local usage of lindane. A positive correlation was found between its concentration in the water phase and the average air temperature during the sampling period. Compounds of the DDT-type, trace amounts of which were detected in only two rain water samples, were determined in most particle samples. The DDE : DDT median concentration ratio in particles was lower than unity and indicated a recent input of DDT into the atmosphere. The incidence and concentrations of di-, tri-, tetra- and pentachlorophenols were higher in snow (single compound concentration 11–527 ng l^–1) than in rain (single compound concentration 2–171 ng l^–1). A quadratic decrease in chlorophenol concentrations in snow and rain with increasing air temperature was observed. Trace amounts of PCDDs and PCDFs were detected in both rain and snow water samples and the highest concentrations were measured for octa-CDD (2 pg l^–1 in snow and 6 pg l^–1 in rain).