城乡交错带溪流沟渠水体氮磷污染特征及环境风险分析

发布时间：2018-05-15 20:36

本文选题：源头溪流 + 水生生物基准　；参考：《合肥工业大学》2017年硕士论文

【摘要】：城乡交错带源头溪流、排水沟渠作为河流水系统的重要组成部分,是汇流区养分汇集、传输和净化的重要场所。由于氮、磷等营养负荷数量可观,并可能会通过水-沉积物界面交换作用进入上覆水,造成水体富营养化并影响下游河流、湖泊水质,因此溪流沟渠兼具"源"与"汇"的特征。本文以合肥城乡交错带3条不同水源补给类型溪流沟渠为对象,按季节采集水样和表层沉积物样,据此开展溪流沟渠水环境状况和沉积物氮、磷赋存形态分析,评估氨氮生态毒性风险和沉积物磷的释放风险,并对沉积物硝化/反硝化潜力进行定量分析,主要研究成果如下:(1)3条溪流沟渠水环境状况差异较大,关镇河支渠污染最为严重,NH_4~+、PO_4~(3-)含量均值分别为26.69 mg·L-1和2.38 mg·L-1。基于氨氮基准生态风险评估,关镇河支渠全年处于高风险水平,陶冲小溪流绝大多数样本为有风险,少数样本为无风险,磨店小溪流仅个别样本有风险;综合水质标识指数法评价结果仅磨店小溪流水环境功能区评价达标。(2)沉积物TN、TP含量高低顺序依次为关镇河支渠陶冲小溪流磨店小溪流。其中,关镇河支渠TN含量平均值为4512.23 mg·kg-1,分别是磨店和陶冲小溪流的2.56、1.36倍。TP含量均值为1376.95 mg·kg-1,为磨店和陶冲小溪流的2.94、1.91倍。3条溪流沟渠几乎都具有一定的生态风险效应,沉积物TN基本均达重度污染水平且均处于有机污染状态。(3)各形态磷含量差异显著,且在含量高低排序方面存在一定差异性;关镇河支渠NH_4~+-N均值为574.43 mg·g-1,是磨店和陶冲小溪流的1.51、1.22倍,NO_3~--N含量均值为72.31 mg·kg-1,是另两条溪流的3.39、1.54倍。(4)3条溪流沉积物PSI值磨店小溪流最高,均值为40.36(mg L)·(100g·μmol)-1,关镇河支渠最低,均值为33.85(mgL)·(100g·μmol)-1、季节性变化总体上都表现出秋季最高,冬季次之,春、夏季基本相当且相对最低的变化特征。由PSI、DPS及ERI评估得到的磷释放风险特征基本一致,相应的磷释放风险高低排序为:关镇河支渠陶冲小溪流磨店小溪流。(5)陶冲小溪流表层沉积物的PNR、ANR相对最高,关镇河支渠相对最低。反硝化速率排序为关镇河支渠陶冲小溪流磨店小溪流。根据参数FvIP,3条溪流沟渠ANR、PNR和反硝化速率几乎都与沉积物的pH、OM、NH_4~+-N、NO_3~--N、TN、TP存在显著或较为显著关系,但不同溪流水体之间存在差异性。
[Abstract]:As an important part of river water system, draining ditch is an important place for nutrient collection, transport and purification in confluence area. Because the amount of nitrogen, phosphorus and other nutrient loads is considerable, and it may enter the overlying water through the interaction of water-sediment interface, resulting in eutrophication of water body and affecting the water quality of the downstream rivers and lakes. Therefore, streams and ditches have the characteristics of "source" and "sink". In this paper, water samples and surface sediment samples were collected from three stream canals of different water supply types in the urban and rural ecotone of Hefei. According to this, the water environment, nitrogen and phosphorus occurrence in stream canals were analyzed. The ecological toxicity risk of ammonia nitrogen and the release risk of phosphorus in sediment were evaluated, and the nitrification / denitrification potential of sediment was quantitatively analyzed. The mean value of NH4 ~ PO4 ~ (3) in Guanzhen River branch canal was 26.69 mg / L and 2.38 mg / L ~ (-1), respectively. Based on the ecological risk assessment of ammonia nitrogen benchmark, Guanzhen River branch canal is at a high risk level in the whole year. Most samples of Tao Chong small stream are risky, a few samples are no risk, and only a few samples of Modian small stream have risk. The result of comprehensive water quality identification index method is that only the evaluation standard of water environment function area of Modian stream is up to standard. 2) the order of TNTP content in sediment is the order of TNTP content in Guanghe branch canal, Tao Chong small stream, Modian stream, and Modian small stream in the branch canal of Guanzhen River. The average TN content in branch canal of Guanzhen River is 4512.23 mg kg ~ (-1), which is 1376.95 mg 路kg ~ (-1). The average of TN content is 1376.95 mg 路kg ~ (-1) in Modian and Tao Chong streams, and almost all of them have ecological risk effect. The TN of sediment reached the level of severe pollution and was in the organic pollution state. The phosphorus content of each form of sediment was significantly different, and there were some differences in the ranking of the contents of TN. The mean value of NH _ 4 ~ -N in branch canal of Guanzhen River is 574.43 mg 路g ~ (-1), which is 1.51 ~ 1.22 times as much as that of Modian and Taochong streams, and the mean value of N is 72.31 mg / kg ~ (-1), which is 3.39 ~ 1.54 times of the other two streams. The PSI value of the sediment of three streams is the highest, the mean value is 40.36(mg L) 100g 渭 mol ~ (-1), and the branch canal of Guanzhen River is the lowest. The mean value is 33.85 mgL) 100g 渭 mol / L, and the seasonal variation is the highest in autumn, followed by winter, and almost equal and relatively lowest in spring and summer. The characteristics of phosphorus release risk assessed by PSI DPS and ERI were basically the same, and the corresponding P release risk was ranked as follows: the order of P release risk was: Tuochong Xiaochong stream Modian Xiaoxiao stream. 5) the PNRANR of surface sediment of Tao Chong stream was the highest. Guanzhen River branch canal is relatively lowest. The order of denitrification rate is Tao Chong stream, Modian stream, branch canal of Guanzhen River. According to the parameters of FvIP, ANRN PNR and denitrification rate almost all have significant or more significant relationship with the pH value of NH _ (4 ~ -N) N _ (10) O _ (3) -N ~ (+) N _ (+) N _ (TNN) _ (TP) in sediments, but there are differences among different streams.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X52

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