安家沟流域不同土地利用方式下地表径流中COD和TN的污染负荷

COD and TN Pollution Loads in Surface Runoff Under Different Land Uses in Anjiagou Basin

为探明黄河流域不同土地利用方式下地表径流中COD和TN污染分布规律,以安家沟流域为研究对象,采用平均浓度模型,对径流来源及其污染负荷进行了分析研究。结果表明:安家沟流域不同土地利用方式下地表径流中7项污染物质量浓度平均超标1.31倍,其中ρ(COD_(Mn))和ρ(TN)分别超标1.78,2.11倍;劣Ⅴ类水质出现的平均频率为23.86%,其中COD_(Mn)和TN平均出现频率分别为28.17%,52.03%;不同土地利用措施受径流量及其拦蓄效率和污染物输出水平的影响,COD_(Mn)和TN两者污染负荷总量主要分布在林地和农地,其单位面积污染负荷以荒坡为最大(2.989kg/hm^2),草地次之(2.937kg/hm^2),林地第三(1.327kg/hm^2),农地最小(0.447kg/hm^2);在坡面到沟道的径流过程中,由于土壤入渗等因子的影响,污染物总量在流域径流过程中具有明显的衰减过程,ρ(COD_(Mn))衰减了40.01%,ρ(TN)衰减了38.33%。研究显示,安家沟流域COD和TN污染在不同土地利用措施之间分异明显,合理规划土地利用方式、加强水土保持措施可有效减轻面源污染的发生。

In order to understand the distribution of COD and TN pollution in different land uses, selecting Anjiagou Basin as the research site, we used the average concentration model to analyze the runoff source and pollution load. The results showed that the concentrations of 7 pollutants in surface runoff were 1.31 times more than the standard under different land uses, in which CODMn and TN exceeded the standard 1.78 times and 2.11 times, respectively; the average occurrence frequency of the water quality worse than grade V was 23.86%, CODgn and TN were 28. 17% and 52.03%, respectively; because of the runoff, impounding efficiency and pollutant output level effect on different land uses, CODMMn and TN pollution loads mainly distributed in the woodland and farmland, the waste hillside of pollution load was maximum in the unit area of CODMn and TN （2. 989 kg/hm^2） , grassland came second（2. 937 kg/hm^2） , woodland third（1. 327 kg/hm^2） was next, and agricultural land was minimum（0. 447 kg/hm^2） ; in the runoff process from slope to channel, due to the effect of soil infiltration and other factors, the total amount of pollutants had obvious attenuation, p（CODMn） and p（TN） decreased by 40.01% and 38.33%, respectively. The results showed that the CODMn pollution and TN pollution were significantly discrepant in different land use, and rational planning of land use, strengthening soil and water conservation measures could effectively reduce the occurrence of non-point source pollution.