漓江上游金龟河试区氮磷浓度时空差异性分析

Temporal and Spatial Variability of Nitrogen and Phosphorus Concentration in Jingui River Region of the Upper Reaches of Lijiang River

为了研究金龟河试区农业面源污染氮磷排放时空分布特征,根据其水力联系在试区内布设了15个监测点,于2017-2018年连续每月监测其氮磷浓度变化,并对两年的水质监测数据进行分析。结果表明:金龟河氮磷浓度总体上呈沿程波动式上升的趋势,在鱼塘排水支流和养殖场排水的支流汇入后,总氮、氨氮和总磷的浓度有明显的上升。在不同下垫面下氨氮与总氮的相关性均显著,相关性大小表现为养殖场>稻田>鱼塘>果林;硝态氮浓度在不同下垫面浓度差异较小。地下水中硝态氮浓度是其他地表水监测点的10倍左右。农田和果林下垫面监测点氮磷浓度总体表现为雨季>干季;养殖场和鱼塘下垫面监测点氮磷浓度表现为干季>雨季。试区内畜禽和水产养殖的氮磷排放对下游水质影响较大,建议加强对养殖废水排放的管理。

In order to study the spatial and temporal distribution characteristics of nitrogen and phosphorus emissions from agricultural nonpoint source pollution in Jingui River Pilot Area,15 monitoring points were set up in the pilot area according to its hydraulic connection.The nitrogen and phosphorus concentration changes were monitored monthly from 2017 to 2018,and the water quality monitoring data of two years were analyzed.The results show that:the concentration of nitrogen and phosphorus in the Jingui River showed a fluctuating upward trend,and the concentrations of total nitrogen,ammonia nitrogen and total phosphorus increased significantly after the tributaries of fish pond drainage and aquaculture wastewater flowed into the river.Under different underlying surfaces,the correlation between ammonia nitrogen and total nitrogen was significant,and the correlation was as follows:Farm>paddy field>fish pond>fruit forest;the concentration of nitrate nitrogen had little difference under different underlying surfaces.The concentration of nitrate nitrogen in groundwater is about 10 times higher than that in other surface water monitoring sites.The results show that the nitrogen and phosphorus concentrations of the monitoring points on the underlying surface of farmland and fruit forest are rainy season>dry season;the concentration of nitrogen and phosphorus on the underlying surface of aquaculture farms and fish ponds was dry season>rainy season.The nitrogen and phosphorus emissions of livestock and aquaculture in the test area have a great impact on the downstream water quality.Strengthening the management of aquaculture wastewater discharge is suggested.