渭河陕西段河道沉积物中碳氮磷来源分析及污染评价

基于渭河陕西段及其支流河道16个采样点中沉积物的总氮(TN)、总磷(TP)和总有机碳(TOC)含量,运用C/N和N/P比值法研究沉积物中营养元素的可能来源,并采用有机污染指数法评价沉积物污染状况。结果表明,沉积物中TN含量为0.069~3.839g/kg,66.1%的样品含量低于平均值0.639g/kg;TP含量为0.453~1.841g/kg,62.7%的样品含量低于平均值0.713g/kg;TOC含量为0.772~25.221g/kg,62.3%的样品含量低于平均值5.609g/kg。渭河陕西段沉积物中有机质主要受内源影响,以藻类和浮游动植物为主;沉积物中磷的来源主要为外源输入。2014—2016年所有采样点的N/P值均小于Redfield比,这可能与沉积物中碳氮磷的生物地球化学过程有关。2016年11月,在局部河道如林家村、卧龙寺桥、常兴桥、兴平、草滩、清姜河入渭处可能受到外源有机质的影响。2015年内有机指数与有机氮指数变化一致,即汛前<汛中<汛后。在2014—2016年,渭河陕西段沉积物中有机氮污染和有机污染整体上得到有效控制,但在局部河道如咸阳铁桥、草滩、黑河入渭和灞河入渭处等距离城市较近区域存在污染反弹可能,需引起注意。

Source Analysis and Pollution Evaluation of Carbon, Nitrogen and Phosphorus in River Sediments of the Weihe River in Shaanxi Province

The contents of total nitrogen (TN), total phosphorus (TP) and total organic carbon (TOC) in 16 sampling points of the Weihe River and its tributary channels were studied, and the possible sources of sediments were studied by C/N and N/P ratio methods. The status of sediment pollution is evaluated by the organic pollution index method. The study shows that the TN content in the sediment is between 0.069~3.839 g/kg, 66.1% of sample content is below the average 0.639 g/kg; the TP content is between 0.453~1.841 g/kg, 62.7% of sample content is below the average. 0.713 g/kg; TOC content is between 0.772~25.221 g/kg, 62.3% of sample content is below the average value of 5.609 g/kg. The organic matter in the sediments of the Weihe River in Shaanxi Province is mainly affected by endogenous sources, and is dominated by algae and phytoplankton. The source of phosphorus in sediments is mainly external input. The N/P values of all sampling points from 2014 to 2016 were less than the Redfield ratio, which may be related to the biogeochemical processes of carbon, nitrogen and phosphorus in sediments. In November 2016, there were external sources of organic matter in partical rivers such as Linjia Village, Wolongsi Bridge, Changxing Bridge, Xingping, Caotan and Qingjiang River. In 2015, the organic index and the organic nitrogen index changed in the same period, namely before the flood