Keywords: 
• polychlorinated biphenyls (PCBs) /
• organochlorine pesticides (OCPs) /
• soil /
• zucchini (Cucurbita pepo L.)

Abstract: Previous studies have indicated that zucchini (Cucurbita pepo L.) has high capacity to accumulate persistent organochlorines from soil. This implies that zucchini can be considered as a potential indicator for the contamination of persistent organochlorines in soils. A field experiment with cultivating zucchini was conducted in this study. The different tissues of zucchini, including roots, transition stems, stems, leaves and fruits were sampled at 6 different growth periods. The concentrations of 21 organochlorine pesticides (OCPs) and 18 polychlorinated biphenyl congeners (PCBs) were determined using the isotope dilution high resolution gas chromatography-high resolution mass spectrometry. The results indicated that OCPs and PCBs absorbed by zucchini roots could be substantially transported to the transition stems and the stems. No significant differences was observed in the concentrations of OCPs and PCBs in roots, transition stems and steams sampled at different growth periods, suggesting that the biological dilution effect did not occur. Meanwhile, the distribution patterns of OCPs and PCB homologs in zucchini roots, transition stems and stems were determined, which were similar to those in soils. Therefore, the concentrations of persistent organochlorines in zucchini roots and stems could be used as indicators for the contamination levels in soils，with benefits of no growth period limitation.