宜宾夜鹭卵中有机氯农药及其代谢物的赋存特征

Occurrence of organochlorine pesticides and their metabolites in black-crowned night heron eggs

于2017年在四川省宜宾市采集黑冠夜鹭(Nycticorax nycticorax)卵样30枚(包括9枚无胚卵和21枚胚胎卵),分析了样品中有机氯农药(OCPs)的残留状况.结果表明,宜宾夜鹭卵中检出了8种OCPs残留物,总含量为4.76~97.9 ng·g^-1(以湿重计).其中,p,p'-滴滴伊(p,p'-DDE)含量最高((20±18)ng·g^-1),其次为六氯苯(HCB,(5.3±3.4)ng·g^-1)和β-六六六(β-HCH,(1.1±0.8)ng·g^-1);滴滴涕类(∑DDTs)中的稳定代谢物p,p'-DDE和六六六类(∑HCHs)中的稳定同分异构体β-HCH占比均在99%以上.p,p'-滴滴涕(p,p'-DDT)和p,p'-DDE在无胚卵蛋液中的残留水平比在胚胎卵蛋液中更高一些,而反式九氯则相反,其余OCPs无差别,这说明鹭卵在孵化过程中p,p'-DDT可能易于代谢,而稳定的p,p'-DDE更容易向胚胎传递.宜宾夜鹭卵中p,p'-DDE的最高含量为84 ng·g^-1,远低于鹭科繁殖效应阈值(1000 ng·g^-1).总体上,夜鹭卵中OCPs的赋存状况较好地反映出长江上游地区OCPs污染水平较低,对夜鹭繁殖的影响较小.

In 2017, the black-crowned night heron (Nycticorax nycticorax) eggs, including 9 embryo-free eggs and 21 embryogenic eggs, were collected from Yibin, Sichuan Province, China. The residues of organochlorine pesticides (OCPs) in heron eggs were analyzed. The result showed that 8 OCPs were found in night heron eggs, with the total concentrations ranged from 4.76 to 97.9 ng·g^-1 (in wet weight). Among the 8 OCPs, p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE,(20±18) ng·g^-1) had the highest concentration, followed by hexachlorobenzene (HCB,(5.3±3.4) ng·g^-1) and beta-hexachlorocyclohexane (β-HCH,(1.1±0.8) ng·g-1). The proportions of p,p'-DDE in DDTs and β-HCH in HCHs were above 99%. The levels of OCPs residues in the embryo-free egg liquids and embryo egg liquids were compared. Both p,p'-dichlorodiphenyltrichloroethylene (p,p'-DDT) and p,p'-DDE were higher in the embryo-free egg liquids while the trans-nonachlor was higher in the embryo egg liquid, while other OCPs in embryo-free and embryo egg liquids were not significantly different. The comparison suggests that p,p'-DDT can be easily metabolized and its stable metabolite p,p'-DDE can be easily transferred to the embryos during hatching. We also found the highest concentration of p,p'-DDE in night heron eggs from Yibin was 84 ng·g^-1, which was much lower than the reproductive effect threshold level of Ardeidae (1000 ng·g^-1). In summary, the characteristics of OCPs in night heron eggs indicate the low level of OCPs pollution at the Upper Yangtze River basin, which has little effect on the reproduction of the night herons.