2010-2020年伶仃洋表层沉积物重金属含量及潜在生态风险变化

Changes in heavy metal content and their potential ecological risk in the surface sediments of Lingding Bay from 2010 to 2020

珠江口是中国重金属污染最严重的河口之一,为了解该河口区近十余年来的重金属污染变化状况,分别于2010和2020年在污染物最易聚集的伶仃洋海域开展了表层沉积物调查取样工作,并使用ICP-MS方法测试了所有样本的V、Cr、Co、Ni、Cu、Zn、Cd、Pb等重金属含量。结果显示,2020年所取沉积物中Cd、Cr、Cu、Zn和Pb的平均含量都比2010年样本的含量显著降低,V和Ni的变化甚微,Co的含量则明显上升。富集系数法和潜在生态危害指数法的评价结果也反映出2020年沉积物中Cd、Cu、Pb、Zn以及Cr的富集程度及潜在生态危害总体上较10年前都有不同程度的缓解,但仍有超过50%的样本中Cd呈现中度—显著富集。V和Ni在2个时期的沉积物中均为轻微富集或基本无富集,但2020年属轻微富集的比例相比2010年有所增加。Co的富集程度及潜在生态危害较2010年加剧,但尚属轻微级。空间上看,伶仃洋4大口门水道,尤其是洪奇沥和蕉门水道,仍为珠江口重金属污染的重灾区,其中,Cd依然是富集程度最高、受人为影响最大且潜在生态风险最强的重金属,其次是Cu和Pb。

The Pearl River estuary(PRE)is one of the estuaries with the most serious heavy metal pollution in China.To understand the changes of heavy metal pollution in this area in the last 10 years,sampling at surface sediments was carried out in 2010 and 2020 at nearly the same locations and quantities in the Lingding Bay area,where pollutants were most likely to accumulate.In addition,the contents of heavy metals(V,Cr,Co,Ni,Cu,Zn,Cd,and Pb)in all the samples were measured by using ICP-MS.Results show that the average contents of Cd,Cr,Cu,Zn,and Pb in the sediment samples collected in 2020 significantly decreased than those of 2010,except for V and Ni whose contents changed slightly,and Co increased significantly.The evaluation results of the enrichment factor method and potential ecological risk index method reflected that the enrichment degree and potential ecological risk of Cd,Cu,Pb,Zn,and Cr in surface sediment of 2020 have been alleviated to varying degrees compared to that 10 years ago.Cd was in moderate to significant enrichment in over half of the samples.V and Ni were not or slightly enriched in both time periods,but the proportion of slight enrichment in 2020 increased compared to 2010.The enrichment degree and potential ecological risk of Co increased compared to 2010,but it was still at a low level.From a spatial perspective,the four major waterways in Lingding Bay,especially the Hongqili and Jiaomen Waterways,were still the places with the most severe heavy metal pollution in PRE.Among the 8 heavy metals in concentration,Cd concentration was the highest,the greatest human impact and the strongest potential ecological risk,followed by Cu and Pb.