【作者】 胡永定；

【导师】 韩宝平；

【作者基本信息】 中国矿业大学 ， 环境科学， 2010， 博士

【摘要】 本论文以徐州市沛沿河区域为研究对象,采用了资料调研、现场定点监测和跟踪监测、室内实验研究和模型模拟相结合的方法,现场采集实验土样近3吨,分析土壤、水样品约520个,共得到分析数据近3300个,系统分析了沛沿河水质的时空动态变化特征,解析了农田面源污染物迁移变化规律,建立了适用于沛沿河区域农田面源污染负荷估算模型,同时研究了面源污染物拦截、治理技术,得出下列研究成果:(1)水质监测表明,沛沿河污染呈现有机污染和营养盐污染特征,主要污染因子为:NH3-N、COD、TP和CODMn;2004年以来沛沿河水质逐年好转,但李集桥国控断面水质仍达不到国家规定的Ⅲ类标准;沛沿河水质受降雨径流的污染影响较大,汛期6-9月水质超标严重。(2)土壤静态释放实验结果表明:土壤中氮磷静态释放是一种吸附-解吸的过程,符合一级动力学模型;不同类型土壤氮磷的释放与其有效态含量和比例大小密切相关,果园土对氮磷的吸附、固定能力较弱,易于释放。施肥后土壤中氮磷的释放能力明显提高,释放量加大;土壤中氮磷的释放强度随换水次数增加而降低,施肥后土壤前3天的释放强度要明显高于后期。(3)采用室内模拟降雨实验,分析在不同条件下农田径流氮、磷、氨氮和CODMn的迁移变化规律,结果表明:a.降雨径流量及泥沙流失量与土壤理化性质和降雨量大小密切相关,在40mm/h和80mm/h的降雨强度下,农田地表径流量大小为:稻田地.>林地>果园地;泥沙流失量大小为:果园地>稻田地>林地;降雨强度越大,水土流失越重;b.地表径流中TP、TN、CODMn和氨氮的浓度随降雨时间的持续呈下降趋势,然后趋于平稳,随着降雨强度的增大径流浓度也相应增加。径流中PN、PP占TN和TP的比例大于DN、DP,尤以PP更为显著,氮、磷的流失主要以颗粒态形式为主;氮磷累积流失量(Y)和径流累积量(Q)之间存在幂指数函数的关系Y=aQb,式中a、b为常数,其大小同降雨强度和土壤地表特征条件有关;c.土壤施肥后径流中TN、TP和氨氮的浓度和流失量成倍增加,尤其是氨氮变化更为突出;施肥前土壤径流中氨氮对水体的污染贡献不大,但施肥后氨氮流失量增加了14.6倍。施肥对径流中的不同形态氮磷的浓度产生显著影响,径流中的DN、DP的浓度快速升高,成为氮磷流失的主要形态,对水体生态环境影响较大,因此农田施肥要避开强度大的降雨,确定合理施肥时间;d.地表覆盖能很大程度上减缓土壤的侵蚀,减少氮磷的流失。在40mm/h降雨强度下,有作物覆盖的土壤径流中TN、TP流失量比裸地分别下降了27.1%和33.3%;在80mm/h降雨强度下,TN、TP流失量比裸地分别下降了51.4%和43.8%。但作物覆盖也会因作物的浸泡使径流中CODMn浓度升高。(4)根据实验结果和沛沿河区域的特点,对SCS径流曲线模型和USLE模型参数以及氮磷流失量计算方法进行合理修正。通过四次单场次暴雨事件的实测验证,总体上模型精度较好。应用该模型计算了沛沿河区域2009年农田面源污染负荷,得到了总氮、总磷和泥沙负荷总量及时间分布规律。结果表明污染负荷与降水量成正相关,泥沙、总氮和总磷污染负荷主要集中在5—7月(污染负荷占全年的80%以上)。这三个月不但是农业耕作和施肥的主要时期,也是降雨主要集中的月份,由降雨所产生的地表径流成为污染物迁移的主要驱动力。(5)通过透水坝、人工湿地和浮水植物净化实验研究,结合沛沿河区域特点,提出了由生态透水坝系统、潜流人工湿地处理系统、生物浮床净化系统和导流系统集成的人工静脉河道生态处理工程措施,以及农业面源污染控制综合管理措施。更多还原

【Abstract】 Taking PeiYan river of Xuzhou as the research object, using the method of literature, field monitoring and track monitoring, laboratory research and model simulation, and getting a total of nearly 3,300 data from nearly 3 tons of soil samples and about 520 water samples, this paper analyzed the spatial-temporal dynamic changes of water quality of PeiYan river and the migration of non-point source pollution from the agricultural field, created the estimation model of non-point source pollution load of PeiYan river, and studied interception and treatment technology of agricultural non-point source pollution. The major conclusions were listed as follows:(1)Water quality monitoring showed that PeiYan river pollution mainly contained organic pollution and nutrient pollution, the main pollution factors were NH3-N, COD, TP and CODMn, and water quality of Pei Yan river has been improved since 2004, but water quality of Li ji bridge state-controlled section still can not reachⅢstandard set by the state. Water quality of Pei Yan river was poorer during the rainy season than during other periods. During the rainy season, especially heavy rain or rainstorms (6-9 month)made non-point source pollutants to PeiYan river, which made water quality far beyond the standard.(2) Nitrogen and phosphorus release of different types of soil before and after fertilization showed that: The release of nitrogen and phosphorus from soil to upper water is an adsorption - desorption process, which can be expressed in first-order kinetics model. The release of nitrogen and phosphorus was affected by different types of land, among them phosphorus release of paddy land was slower than other soils, but that of orchard land was reversed. Fertilization improved markedly the release of soil nitrogen and phosphorus. Increasing the number of changing water times nitrogen and phosphorus release intensity decreased, and the release intensity after fertilization on the first 3 days was significantly higher than the latter.(3) Under different rainfall intensity, different types of soil, different land cover and fertilization, migration of nitrogen, phosphorus, ammonia nitrogen and CODMn in the farmland runoff was studied by taking the indoor simulated rainfall experiment. The results showed that: a. The runoff and sediment concentration in runoff changed as different physical and chemical properties of different types of soil .Under 40mm / h and 80mm / h , the order of the size of farmland surface runoff was paddy land.> forest land > orchard land and that of erosion sediment transport was orchard land> paddy land> forest land. There was a positive correlation between rainfall intensity and soil erosion. b.TP, TN, CODMn and ammonia concentration in surface runoff decreased with duration of rainfall, and then tended to be stable. And TP, TN, CODMn and ammonia concentration in surface runoff increased with the increasing of rainfall intensity. The proportion of PN and PP of total nitrogen and total phosphorus was greater than that of DN and DP, and the proportion of PN and PP significantly increased with the increasing of rainfall intensity, especially PP, which showed that granule state was the main form of nitrogen and phosphorus loss in rainfall runoff. The relationship between the cumulative amount of nitrogen and phosphorus loss (Y) and the cumulative amount of runoff (Q) was Y = aQb, in which a and b were constants and they were affected by rainfall intensity and characteristics of soil surface. c. Nitrogen and phosphorus concentration in runoff significantly increased after fertilizer, especially ammonia nitrogen concentration increased more than 10 times. Fertilization had a significant influence on the concentration of different forms of nitrogen and phosphorus in runoff, among them, DN and DP concentration were significantly increased, which showed that fertilizer applied to soil was not easy to be absorbed and fixed in a short time, so farm fertilization should avoid rainfall time to reduce nitrogen and phosphorus loss. d. Crop cover made nitrogen, phosphorus and ammonia nitrogen concentration in soil runoff decrease significantly, and farmland surface cover could significantly reduce soil erosion and nitrogen and phosphorus loss. Under 40mm/h rainfall intensity, TN and TP loss dropped 27.1% and 33.3% respectively in covered soil than bare area in runoff; Under 80mm/h rainfall intensity, TN and TP loss dropped 51.4% and 43.8% respectively .However, cover crop immersion also increased CODMn concentration.(4)The runoff curve of SCS model and USLE models were modified according to the characteristics of the PeiYan river region. The coefficient of nitrogen and phosphorus in water distribution was calculated based on the experiment results, correcting the traditional calculation ways reasonably. Screening comparing with the measured and simulated values by a single storm event four times, the accuracy of model was fine overall. Appling to the model to accout the non-point source pollution load of farmland along the PeiYan river region in 2009, we got the total nitrogen, total phosphorus, total sediment load and time distribution law. The results show that the pollution load was positively a direct proportion correlated with precipitation, while sediment, the pollution load of total nitrogen and total phosphorus were concentrated in May, June and July (accounting for more than 80% of the annual total pollution load). The three months were not only the main period of farming fertilization, but the main focus rainfall months, and the runoff generated from rainfall became a key driver of transport of pollutants.(5)Through the purificatory experimental study on the ecosystem dam, artificial wetland and submersed plants, combining the characteristics of PeiYan river regional, the engineering measures such as the artificial vein ecological river settlement which was composed of ecosystem dam system, undercurrents of artificial wetland system , biological floating bed purification system and the diversion of integrated system and the coastwise buffer zone settlement , the integrated management measures of agricultural non-point source pollution control have been put forward.更多还原