三峡库区笋溪河流域面源污染及其与土壤可蚀性k值的关系

研究三峡库区面源污染特征及其与水土流失的关系,可为库区氮磷污染和土壤侵蚀控制提供依据.选择三峡库区库尾笋溪河流域,在流域内分园地、林地和耕地3种土地利用类型共采集126个土壤样品,并在主干和支流采集52个水质样品.根据EPIC模型计算土壤可蚀性k值,分析流域内土壤可蚀性k值对面源污染的影响.结果表明,笋溪河流域面源污染主要是氮污染,总氮均值达1.37 mg/L,氮素的主要形态为硝态氮,占总氮的71.2%;总磷浓度为0.1 mg/L.流域内土壤可蚀性k值均值为0.040,随着土层加深土壤可蚀性k值呈上升趋势;林地土壤可蚀性k值显著低于园地和耕地.笋溪河流域总氮浓度与园地和耕地0-20 cm土壤可蚀性k值有关,硝态氮浓度与耕地0-40 cm土壤可蚀性k值有关.因此,笋溪河流域面源污染严重,主要来源是耕地和园地,应实行免耕、植物篱等措施,同时减少化肥施用,增加有机肥比例,以增加土壤抗侵蚀能力,进而控制流域水土流失和面源污染.(图6参37)

Non-point source pollution and its relationship with soil erodibility k value in the Sunxi River watershed,Three Gorges Reservoir Area

Studying the characteristics of non-point source pollution and its relationship with soil erosion in the Three Gorges Reservoir Area can provide a basis for nitrogen and phosphorus pollution and soil erosion control in the area. A total of 126 soil samples were collected from the three types of land use, including garden, forestland, and cultivated land, and 52 water samples were collected from the trunk and tributaries along the Sunxi River watershed. Soil erodibility k value was calculated according to the EPIC model, and the influence of soil erodibility k value on non-point source pollution in the watershed was analyzed. The results showed that the non-point source pollution in the Sunxi River watershed was mainly nitrogen, with an average total nitrogen of 1.37 mg/L. The main form of nitrogen was nitrate nitrogen, accounting for 71.2% of the total nitrogen. The total phosphorus concentration was 0.1 mg/L. Soil erodibility k increased with an increase in soil depth, and its mean in the watershed was 0.040;the erodibility k of forestland was significantly lower than that of garden and cultivated land. The total nitrogen concentration in the Sunxi River watershed was related to soil erodibility k value of the garden and cultivated land at a depth of 0-20 cm, and nitrate nitrogen concentration was related to soil erodibility k value of the cultivated land at 0-40 cm. Planting of hedges and other measures should be implemented in cultivated land and gardens. At the same time, the application of chemical fertilizers should be reduced, and the proportion of organic fertilizer used should be increased to increase the ability of the soil to resist erosion, thereby controlling water and soil loss and non-point source pollution.