论文部分内容阅读
农业源头沟渠是连接农田排水与河流的重要通道,对农业非点源污染物具有很高的削减作用。反硝化作用是沟渠水体氮污染去除最彻底的机制,但目前相关研究缺乏。利用改进的乙炔抑制法研究川中丘陵区农业源头沟渠沉积物反硝化作用的速率、季节变化及影响因素,以期为长江上游农业水环境保护提供新的思路。结果表明:1)农业源头沟渠沉积物反硝化速率变化范围在0.31~43.11mg·m~(-2)·h~(-1)之间,平均值为10.45mg·m~(-2)·h~(-1);2)沟渠反硝化速率具有明显的季节差异,冬季沟渠沉积物反硝化速率普遍偏低,而夏季则具有较强的反硝化作用,不同季节的反硝化速率大小顺序为:夏季>春季>秋季>冬季;3)沟渠反硝化作用受水文条件、水体沉积物碳氮浓度等因素影响。其中,水文条件不同的区域反硝化速率的大小顺序为:间歇滞水区>干湿交替区>常年淹水区;沉积物和上覆水NO-3-N,DOC浓度与反硝化速率之间具有显著的正相关关系。总体来说,川中丘陵区农业源头沟渠具有较高的反硝化速率,通过增加碳源或改善水文条件能有效地促进沟渠沉积物的反硝化作用,从而极大地提高农业源头沟渠对非点源氮污染的截控能力。
Agricultural source ditches are an important channel connecting farmland drainage and rivers and have a very high reduction effect on agricultural non-point source pollutants. Denitrification is the most thorough removal mechanism of nitrogen pollution in ditch water, but the current research is lacking. The improved method of acetylene inhibition was used to study the denitrification rate, seasonal variation and influencing factors of agricultural source ditch sediments in the hilly area of central Sichuan Basin, with a view to providing new ideas for the agricultural water environment protection in the upper reaches of the Yangtze River. The results showed that: 1) The denitrification rate of sediment in agricultural source ditches varied from 0.31 to 43.11 mg · m -2 · h -1 with an average of 10.45 mg · m -2 · · h ~ (-1). 2) The denitrification rate of ditches has obvious seasonal difference. The denitrification rate of ditches sediments in winter is generally low, while denitrification is strong in summer. The order of denitrification rates in different seasons is : Summer> Spring> Autumn> Winter; 3) Ditches denitrification is affected by hydrological conditions, carbon and nitrogen concentrations in sediments and other factors. Among them, the order of denitrification rate in different regional hydrological conditions is as follows: intermittent stagnant water area> wet-dry alternating area> perennial flooded area; between sediment and overlying water NO-3-N, DOC concentration and denitrification rate have Significant positive correlation. In general, the agricultural source ditches in the hilly area of central Sichuan have a high denitrification rate, which can effectively promote the denitrification of ditches and sediments by increasing the carbon source or improving the hydrological conditions, thereby greatly improving the effect of agricultural source ditches on non-point source nitrogen Contamination control ability.