西葫芦对土壤持久性有机氯化物污染的指示性研究

西葫芦(Cucurbita pepo L.)对土壤中持久性有机氯化物的超强吸收能力已被证实,意味其具有指示区域土壤持久性有机氯化物污染状况的潜能。本研究采用农田小区试验,考察了西葫芦不同组织器官(根、过渡茎、茎、叶和果实)在6个生长期对有机氯化物的累积吸收行为;采用同位素稀释高分辨气相色谱-高分辨质谱法,分析了种植土壤及西葫芦各组织器官中的21种有机氯农药(OCPs)和18种多氯联苯(PCBs)。结果表明,西葫芦可将根吸收的OCPs和PCBs传递到过渡茎和茎。不同生长期采集的西葫芦根、过渡茎和茎中的OCPs和PCBs浓度基本稳定,无明显生物稀释效应,且此3个组织器官中OCPs和PCBs的分布模式与土壤中的分布模式基本一致。因此,可以用西葫芦根和茎中持久性有机氯化物的浓度指示土壤中持久性有机氯化物的污染水平,根和茎的采样时间可以不受西葫芦生长期的限制。

Indicator Role of Zucchini (Cucurbita pepo L.) for the Pollution Levels of Persistent Organochlorines in Soils

Previous studies have indicated that zucchini (Cucurbitapepo L.) has high capacity to accumulate persis-tent organochlorines from soil. This implies that zucchini can be considered as a potential indicator for the contami-nation 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 bi-phenyl congeners (PCBs) were determined using the isotope dilution high resolution gas chromatography-high res-olution mass spectrometry. The results indicated that OCPs and PCBs absorbed by zucchini roots could be substan-tially transported to the transition stems and the stems. No significant differences was observed in the concentra-tions 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 con-centrations of persistent organochlorines in zucchini roots and stems could be used as indicators for the contamina-tion levels in soils,with benefits of no growth period limitation.