赤水河流域中游沉积物营养元素分布特征及污染评价

Study on distribution characteristics and pollution evaluation of nutrient elements in surface sediments in the middle Chishui River,southwestern China

河流沉积物作为流域营养物质(碳、氮、磷)的汇与源,研究其含量与分布特征,对了解流域水环境污染现状具有重要意义。通过测定赤水河中游五马河-大同河段表层沉积物有机质和营养元素(总有机碳、总氮、总磷)含量,发现:河段沉积物有机质和营养元素含量呈现出较大的空间分布差异特征,其中,盐津河、茅台镇断面营养元素和有机质含量明显高于其他断面,显示出有机质和氮磷复合污染特征,可能主要与仁怀市市区和茅台镇人口密集以及人为活动强度大有关,如城镇生活污水和酿酒工业废水向河流输入大量氮、磷营养物质。通过对赤水河中游沉积物营养元素空间分布特征及污染评价进行研究,能够为有效治理和保护赤水河水质提供理论依据。

Background,aim,and scope As a sink and source of nutrients(e.g.,carbon,nitrogen and phosphorus)in the catchment-river systems,the study on the contents and distribution characteristics of nutrients in river sediments has a crucial role in understanding the water environmental pollution.In this paper,river sediments from the middle Chishui River,southwestern China were used to study the distribution characteristics and pollution evaluation of nutrient elements.Materials and methods Thirteen surface sediment samples were collected from the middle reaches of Chishui River,including ten sediment sampling points in the main stream and three sediments in tributaries.The sediment samples were freeze-dried,removed gravel,shells and weeds and then milled to 100-mesh.We determined the contents of organic matter and total organic carbon(TOC),total nitrogen(TN)and total phosphorus(TP)in the surface sediments.Results The organic matter and nutrient element contents in the sediments showed significant difference in spatial distribution.Among them,the contents of nutrients and organic matter in the sediments of Yanjin River and Maotai Section were significantly higher than the other sampling sites,showing combined pollution characteristics of organic matter and nitrogenphosphorus.Discussion Organic matter and nitrogen and phosphorus combined pollution characteristics appear in each sampling sites,especially the Renhuai City and Maotai Town.It may be related to the dense population and intense human activities in Renhuai City and Maotai Town,such as urban sewage and industrial wastewater inputting a large amount of nitrogen and phosphorus into the river.Conclusions The spatial distribution characteristics of nutrient elements in sediments of Chishui River were studied to provide theoretical basis for effective management and protection of Chishui River.Recommendations and perspectives More attention should be pay to the nitrogen and phosphorus treatment of Yanjin River and Maotai Town in the future.Further research into the factors affecting pollution in the region is needed.