Rasearch On Residues Of Organoclorine Pesticides From Typicial Mediums In Urban Parks Of Beijing

Urban parks are important leisure places for citizens and indispensable part of urban environment, the environmental quality of which have important influence on human lives and health. This paper studied the residues and enantiomeric signature of typical organochlorine pesticides (HCHs and DDTs, et al) in urban pine needle, earthworm and soil in Beijing combined with chiral/non-chiral column gas chromatography-electron capture detector (GC-ECD) and gas-mass (GC-LRMS). The aim of this study was to provide information to assess the extent of contamination and source of organochlorine pesticides in urban environment and get preliminary understanding about the ecological safety and risk in urban leisure facilities.The results showed that the total concentrations of HCHs and DDTs decreased with time in Beijing and the residue of DDTs was still high. The pollution of HCHs may be atmospheric deposition from area source; the volatilization of DDTs from soil may be an important source of DDTs. The residue of HCB was still high and had a trend to increase, which should be paid more attention to. a-HCH and o,p'-DDT presented (+)-enantiomer or (-)-enantiomer preferential degradation in pine needles. On account of the function of pine needle as atmospheric bio-indicator, this study implies the similar condition of DDTs and HCB in the atmospheric, which also need to be focused on.The pollution conditions of earthworms and soils present much similarity. The residues of DDTs in earthworms and soil were both much higher than their respective concentrations of HCHs and HCB, which suggests a potential threaten to the ecosystem and food chain in parks. On the basis of the characteristic ratios of HCHs and DDTs as well as the enantiomeric fractions (EFs) ofα-HCH and o,p'-DDT in earthworms and soils, it was deduced that there may be no new input of HCHs and DDTs. HCHs may derive from historical usage of technical HCHs and Lindane while the pollution sources of DDTs may be aged DDTs residue and recent appliance of dicofol. The residue of HCB in earthworms may mainly be accumulated from the pollutants in soil where they lived, whereas the residue of HCB in soils of Beijing may come from atmospheric deposition.