四川丘陵农区地表水水质时空变化与污染现状评价

为分析四川丘陵典型农区种养格局对地表水水质的影响,于2013年3月至2015年2月,在四川丘陵区中江县选择响滩河7个监测断面和流域内4个研究点,研究了种植区、养殖区和种养混合区的地表水水体CODCr、TN、NO3--N、NH4+-N和TP的季节性变化规律与空间变化特征,并对地表水质污染现状进行评价。结果表明:响滩河7个监测断面枯水期主要污染物为CODCr、NH4+-N和TP,且分别比年平均值提高15.67%、59.35%和12.83%;丰水期主要污染物为TN,比年平均值提高19.27%。种养格局影响地表水中TN、NO3--N、NH4+-N和TP浓度的空间分布特征,不同区域之间养殖区种养混合区种植区;与种植区相比,生猪规模化养殖废污排放是造成种养混合区地表水污染的根本原因,其CODCr、TN、NO3--N、NH4+-N和TP浓度分别提高了17.79%、198.15%、132.10%、219.85%、567.57%。规模化养殖显著提高了地表水总污染指数,改变了地表水污染类型,种植区地表水污染类型为兼有CODCr污染的总氮污染型,而养殖区和种养结合区地表水均为兼有总磷污染的总氮污染型;种植区和种养混合区水质均达到劣Ⅴ类水质标准,种植区地表水为轻度污染,养殖区和受养殖业污染影响的种养混合区的地表水均为恶性污染,生猪集中养殖特别是规模化生猪养殖场废污排放加剧了受纳水体的污染程度。从水体污染治理角度,在种植区开展水土养分流失特别是氮素流失控制的同时,亟需加强区域生猪规模化养殖业粪污的无害化资源化循环利用技术研究与应用,以促进四川丘陵区规模养殖业健康发展与长江上游生态环境保护。

Variation of surface water quality based on crop-livestock structure change and its pollution assessment in Sichuan Hilly Area

Abstract: In order to analyze the influence of crop-livestock structure to the seasonal change and spatial variation characteristics of surface water in Sichuan Hilly Area, the water quality indexes including CODC r,TN, NO3--N, NH4+-N and TP were investigated from March 2013 to February 2015 in Zhongjiang county of Sichuan province, based on seven monitoring sections in Xiangtan river and four research points in Zhenggouwan small watershed, and the water quality pollution status was also evaluated by using single factor evaluation method and the comprehensive pollution index method. The outcomes showed that in low flow period, CODcr, NH4+-N and TP were major pollutants of surface water in seven monitoring sections in Xiangtan river, and their concentrations were 15.67% ,59.35% and 12.83% higher than that of the annual average value respectively. In high water period, the major pollutant was TN, and its concentration value increased by 19.27 % comparing with that of the annual average value. The concentrations of TN, NO3--N, NH4+-N and TP of surface water in different areas followed the order that Livestock Farms > Planting Regions & Livestock Farm > Planting Regions in Xiangtan river, and Large-scale pig farming''s waste emissions was the root cause of surface water pollution in Planting Regions & Livestock Farm area, and the CODcr, TN, NO3--N, NH4+-N and TP concentrations of surface water in this area increased by 17.79%, 198.15%, 132.10%, 219.85%, 567.57% respectively, comparing with that of Planting Regions. Both the Large scale pig farming in Xiangtan river and below designated size pig farming in Zhenggouwan small watershed significantly increased the total surface water pollution index, it also changed the type of surface water pollution, and in Planting Regions, the surface water pollution type was TN - CODcr pollution, but that was TN - TP pollution in both of Livestock Farms and Planting Regions & Livestock Farm area. According to the results of single factor evaluation method, the surface water pollution was serious in seven monitoring sections in Xiangtan river and four research points in Zhenggouwan small watershed, and their water quality all reached inferior V class water quality standard, on the basis of "surface water environment quality standard (GB 3838-2002)". The crop-livestock structure also changed the degree of surface water pollution, and the Nemerow Pollution Indexes of surface water in Planting Regions in both Xiangtan river and Zhenggouwan small watershed were 2.95and 2.89, but that were 8.93 and 5.56 in Planting Regions & Livestock Farm respectively, so centralized Pig breeding particularly large scale pig farming''s waste emissions exacerbated degree of surface water pollution to its downstream receiving waters. From the perspective of water pollution control, it is essential to launch control of water loss ,soil erosion and soil nutrient loss, especially nitrogen loss in Planting Regions in Sichuan Hilly Area, at the same time, urgently need to strengthen technology research about harmless treatments and resource recycling utilization of livestock residues, to promote the healthy development of Sichuan hilly area and ensure ecological environment of the upper reaches of the Yangtze river.