望虞河西岸河网区沉积物营养盐和重金属污染时空分布特征

以无锡市望虞河西岸河网区为研究区域,于2018年12月—2019年9月分冬、春、夏、秋4个季节采集了上覆水和沉积物样本,研究氮磷营养因子在沉积物-上覆水界面的释放规律,探究主要水质指标、沉积物氮磷和重金属含量的时空分布特征。结果表明:研究区域内的水质状况不佳,主要是氮含量超标,污染严重的点位集中在人类活动较为密集的市区和工业区;受上覆水氮磷浓度、溶解氧浓度等变化的影响,沉积物营养盐含量季节变化明显,污染状况较为严重,75%的点位属于中度和重度污染;沉积物重金属含量季节变化不显著,部分重金属的空间分布特征相似,污染程度排序为Zn>Cd>Cu>Pb>Ni>Cr>As。

Spatial and Temporal Distribution of Nutrients and Heavy Metals Pollution in the River Network Area on the West Bank of the Wangyu River

Taking the river network area on the west bank of the Wangyu River in Wuxi City as the study area,overlying water and sediment samples were collected in four seasons from December 2018 to September 2019.The aim of this study was to disentangle the release patterns of nutrient factors (including nitrogen and phosphorus) at the sediment-overlying water interface and explore the spatial and temporal distribution of water quality,sediment nitrogen and phosphorus and heavy metals.The results showed that the poor water quality in the study area was mainly due to excessive nitrogen content.The most polluted areas were concentrated in cities and industrial areas with intensive human activities.In terms of nutrients,the pollution in sediment was primally influenced by nitrogen,phosphorus,dissolved oxygen and other factors in the overlying water.75% of the studied points were moderately and heavily polluted with seasonal pollution features.While heavy metal contamination in selected areas did not exhibit seasonal characteristics,certain heavy metal species showed similar spatial distribution patterns.Overall,the heavy metal pollution level in descending order were:Zn>Cd>Cu>Pb>Ni>Cr>As.