宁夏引黄灌区典型排水沟排域面源污染现状研究

Analysis and Research on the Current Situation of Non-point Source Pollution in Typical Drainage Ditches of Ningxia in the Yellow River Irrigation Area

以宁夏引黄灌区第六排水沟排域为研究对象,采取调查和监测相结合的方式,开展第六排水沟排域农业生产方式网格化调研和沟道退水水体监测与评价,旨在揭示排域内氮磷流失的时空变化规律,评估排域内农田面源污染对排水沟退水的影响。结果表明:排域内化肥施用强度在82~86 kg/667 m^(2),化肥施用量、流失量均以氮肥最高;5-9月排域退水污染物浓度的变化总体上呈逐渐下降趋势,总氮和总磷除5-7月份属于Ⅲ-Ⅳ类水质标准,其余时段均优于Ⅲ类水,氨氮除5月份属于Ⅲ类水,其余时段均优于Ⅱ类水;排域输出污染负荷结果显示,排域内氮肥施用过量。

Taking the sixth drainage ditch area of Ningxia in the Yellow River Irrigation Area as the research object,a combination of investigation and monitoring was adopted to conduct grid research on agricultural production methods and monitoring and evaluation of drainage ditch drainage water bodies in the sixth drainage ditch drainage area.The aim was to reveal the spatiotemporal changes in nitrogen and phosphorus loss within the drainage area and evaluate the impact of farmland non-point source pollution on drainage ditch drainage.The results showed that the application intensity of chemical fertilizers in the drainage area was 82~86 kg/667 m^(2),and nitrogen fertilizer had the highest amount of fertilizer application and loss;The changes in the concentration of pollutants in the discharged water from May to September generally show a gradual downward trend,with total nitrogen and total phosphorus being excluded from May to July ClassⅢ-IV water quality standard,superior to other time periods ClassⅢ,except for May,ammonia nitrogen belongs to ClassⅢ,better than other time periods ClassⅡ;The output pollution load results of the drainage area show that nitrogen fertilizer is excessively applied within the drainage area.