东北黑土区典型小流域农业面源污染源解析及防控措施效果评估

发布时间：2017-12-27 03:10

本文关键词：东北黑土区典型小流域农业面源污染源解析及防控措施效果评估　出处：《中国科学院研究生院(东北地理与农业生态研究所)》2016年博士论文　论文类型：学位论文

【摘要】：由农业面源污染导致的水环境质量下降和水生态系统破坏是全世界共同关注的重要环境问题,水土流失既是面源污染发生的动力也是污染物迁移的载体。因此,识别水土流失特征,明确农业面源污染来源及主要影响因素,并采取有效防控措施对改善农业面源污染现状,加快水生态环境修复重建、流域水资源管理具有重要意义。本研究选择东北低山丘陵区典型小流域(吉林省东辽县杏木小流域)为研究对象,采取标准小区定位监测、野外试验观测相结合的方法,研究了坡面和小流域尺度农业面源污染特征,分析了典型污染物主要来源及贡献率,评估了典型面源污染防控措施的效果。通过研究得出以下主要结论:(1)研究区侵蚀性降雨主要发生在6-8月,降雨量和雨强是影响坡耕地水土流失和面源污染物输出的重要因素,且表现为显著的正线性相关性。坡度也是坡耕地水土流失和面源污染物输出的重要影响因素。(2)坡耕地径流中总氮(TN)和总磷(TP)的浓度均超过“地表水环境质量标准”Ⅴ类水限值。氮(N)是坡耕地输出的主要面源污染物,2013-2014年TN的年输出量占面源污染物总输出量的55%-69%。(3)坡耕地径流中NH4+-N浓度值最高,村屯径流中NO3--N、TN和TP浓度值最高;不同土地利用方式下,四种面源污染物输出负荷大小为耕地林地村屯,对小流域面源污染物输出的贡献率分别为68.0%-70.7%,16.0%-21.3%和10.7%-13.3%。N是小流域最主要的农业面源污染物,硝态氮(NO3--N)输出负荷大于铵态氮(NH4+-N)。(4)坡耕地径流中NO3--N和NH4+-N主要来源分别为大气降雨、土壤和化肥,林地径流中两种形态N来源为大气降雨和土壤,而村屯径流中N主要来源于大气降雨、生活污水和排泄物。2013-2014年土壤源对坡耕地、林地地表径流中NO3--N的贡献率最大,分别为51.38%-54.13%和52.82%-69.11%;农村生活污水和畜禽排泄物污染源分别在2013(51.30%)和2014年(50.64%)对村屯径流中NO3--N的贡献率最大。(5)垄向区田措施防治水土流失和面源污染的效果显著,不同区田处理5-9月径流量削减54%-68%,泥沙量流失降低91%-97%,粮食产量增长14.96%-25.67%,75 cm档距处理水土保持效果好于65 cm、85 cm档距,并且75 cm档距面源污染负荷削减效果最佳;垄向区田4种面源污染物年输出量削减率可达80.60%-93.47%。(6)植草带措施能够延迟产流发生时间,显著减少坡耕地水土流失量及面源污染物输出负荷。苜蓿草带在5-9月份径流削减率达到55.36%-100%,泥沙削减率达91.47%-98.03%,四种面源污染物输出负荷的削减率达到68.85%-90.23%;自然恢复草带径流、泥沙削减率分别为6.66%-100%、76.11%-89.63%,面源污染物输出负荷削减率达15.82%-73.90%,苜蓿草带的污染防控效果优于自然恢复的植被草带。总体而言,N、O同位素技术能够较好的应用于农业面源污染源解析,为有效开展农业面源污染防治工作提供了科学依据;垄向区田和植草带两种措施具有良好的面源污染防控效果,能够在源头上减少东北黑土区坡耕地水土流失和农业面源污染,削减污染物负荷输出,降低对水体环境的危害,尤其适宜在黑土区水源地流域水土保持及生态环境恢复与重建工作中进行推广应用。
[Abstract]:The decline of water environment quality and the destruction of water ecosystem caused by agricultural non-point source pollution is an important environmental problem all over the world. Soil and water loss is both the driving force of non-point source pollution and the carrier of pollutant migration. Therefore, identifying the characteristics of soil and water loss, identifying the sources and main influencing factors of agricultural non-point source pollution, and taking effective prevention and control measures are of great significance for improving the current situation of agricultural non-point source pollution, speeding up the rehabilitation and reconstruction of water ecological environment, and managing water resources in river basins. This study selects typical small watershed of hilly region in Northeast China (Dongliao County of Jilin province apricot wood small watershed) as the research object, adopt the method of standard cell positioning monitoring, field observation of combining the characteristics of slope and Small Watershed Agricultural non-point source pollution, analyzes the main sources and the contribution rate of typical pollutants, evaluation. The typical non-point source pollution prevention and control measures of the effect. The following conclusions can be drawn from the study: (1) the erosive rainfall in the study area mainly occurred in 6-8 months, and rainfall and rainfall intensity were the important factors that affected soil and water loss and the output of non-point source pollutants, and showed a significant positive linear correlation. Slope is also an important factor affecting soil and water loss and the output of non-point source pollutants in sloping land. (2) the concentration of total nitrogen (TN) and total phosphorus (TP) in the runoff of sloping farmland is more than the water limit of the "surface water environmental quality standard". Nitrogen (N) is the main surface source pollutant in the output of slope farmland, and the annual output of TN in 2013-2014 years accounts for 55%-69% of the total output of the source pollutants. (3) the runoff in slope land value is the highest concentration of NH4+-N, NO3--N, TN and villages in the runoff TP concentration is highest; the different land use patterns, four kinds of non-point source pollutants output load into farmland woodland villages of small watershed non-point source pollutant output accounted for 68.0%-70.7%, 16.0%-21.3% and 10.7%-13.3%. N is the main agricultural non-point source pollutant in small watershed, and the output load of nitrate nitrogen (NO3--N) is greater than ammonium nitrogen (NH4+-N). (4) NO3--N and NH4+-N were the main sources in slope farmland runoff to rainfall, soil and fertilizer, woodland runoff in two forms of N source for atmospheric rainfall and soil, and villages in runoff N mainly from rainfall, sewage and waste. 2013-2014 soil source on NO3--N slope land, runoff in the maximum contribution rate were 51.38%-54.13% and 52.82%-69.11%; rural sewage and livestock excreta pollution sources in 2013 (51.30%) and 2014 (50.64%) the maximum rate of NO3--N in runoff contribution. (5) to control soil ridge area measures of erosion and non-point source pollution effect, different area 5-9 monthly runoff reduced 54%-68%, sediment erosion decreased 91%-97%, grain yield increase of 14.96%-25.67%, 75 cm span treatment effect of soil and water conservation in 65 cm, 85 cm and 75 cm span, the span of non-point source pollution the effect of the optimal load shedding; ridge tillage 4 kinds of non-point source pollutants annual output reduction rate of up to 80.60%-93.47%. (6) take measures to delay planting runoff occurrence time, and significantly reduce the amount of non-point source pollution load of slope farmland soil erosion. Alfalfa with 5-9 month runoff reduction rate reached 55.36%-100%, the sediment reduction rate reached 91.47%-98.03%, four kinds of non-point source pollutants output load reduction rate reached 68.85%-90.23%; natural restoration with grass runoff and sediment reduction rate were 6.66%-100%, 76.11%-89.63%, non-point source pollutant output load reduction rate of 15.82%-73.90% is better than that of pollution prevention and control effect of alfalfa belt the natural restoration of vegetation with grass. Overall, N and O isotope technology can be better applied to the agricultural non-point pollution source analysis, provide a scientific basis for effective prevention and control of agricultural non-point source pollution; ridge with two kinds of measures to field planting and non-point source pollution prevention and control has good effect, can reduce the slope coveron soil erosion and Agriculture Non-point source pollution at the source, reduce pollutant load output, reduce the harm to the aquatic environment, especially suitable for soil and water conservation in the water basin soil area and restoration of the ecological environment and promote the application of reconstruction work.
【学位授予单位】：中国科学院研究生院(东北地理与农业生态研究所)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：X71;X52

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