IMHE OpenIR  > 山地表生过程与生态调控重点实验室
川中丘陵区排水沟渠反硝化脱氮效率特征
Alternative TitleDenitrification Efficiency in Drainage Ditches in the Central Sichuan Basin
Language中文
赵原
Thesis Advisor高美荣 ; 汪涛
2015
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name硕士
Degree Discipline环境工程
Keyword川中丘陵区 沟渠 反硝化脱氮 野外调查 定点监测
Abstract氮是农业生产最重要的养分限制因子,同时也是日益增长的环境污染因子。进入生物圈的活性氮的数量已经大大超过了自然生态系统生物固氮的量。过量的活性氮进入生态系统,破坏了氮素平衡,可能导致严重的环境问题,如水体富营养化问题已成我国最突出的水环境问题。近期数百亿资金投入到水体氮污染治理,但水体富营养化的改善成效甚微,并日趋严重,除工业污染未得到有效抑制外,农业非点源氮污染加剧成为重要的原因。在氮循环中,反硝化过程将活化的氮以N2形式返回到大气圈的过程,它起着闭合全球氮循环的作用,在生物圈的氮循环中起着枢纽作用。因此,反硝化这个造成陆地生物有效氮损失的过程,被认为是对大气中作为惰性氮形态(N2)的恢复和补给过程。排水沟渠贯穿于山丘区的所有地貌,是径流、泥沙及其携带迁移污染物的通道,但同时沟渠系统通过沉积物的吸附、生物转化等作用对污染物(包括氮)进行截留、消减和净化。四川盆地地处长江上游,排水汇流沟渠纵横交错,是连接农业排水、村镇居民生活废水与河流湖泊的重要通道。作为污染物质传输的重要通道,沟渠不仅起到了输移功能,而且良好的沟渠系统能起到消减污染负荷、净化水质的功能。反硝化作用可能是沟渠水体氮素去除的重要方式。但沟渠中水体反硝化脱氮机制缺乏深入研究,难以评估反硝化脱氮对水体氮污染去除的贡献。本论文通过对川中丘陵区排水沟渠特征与脱氮功能的调查与定位观测,结合实验室反硝化脱氮效率的模拟研究,探讨排水沟渠的反硝化脱氮作用机制与效率,为提高四川盆地山丘区沟渠活性氮的去除效率,减少长江上游水体活性氮输入,保护长江流域水环境具有重要意义。研究的主要结果与结论如下: (1)野外调查自然沟渠 川中丘陵排水沟渠水体整体富营养化情况严重。其中TN含量均高于国家地表水五类水2.0mg/L的标准,污染严重,其中9.72%的水体高于10mg/L。沟渠水体TP平均含量低于国家地表水三类水0.2mg/L的标准。但是,68.06%的水体TP含量超过了富营养化0.02mg/L的标准,31.94%的沟渠水体含量高于0.2mg/L,有些甚至超过了五类水0.4mg/L的标准。97.97%的沟渠水体中颗粒态氮含量占总氮含量的比例小于50%。 川中丘陵区沉积物中的磷消长主要以颗粒态磷为主,沉积在沉积物内,可溶态磷极少,故而沉积物内的磷的形态相对比较稳定。而水体中的铵态氮极易被氧化成为硝态氮,其变异系数较大。 川中丘陵区沟渠湿地植物以过江草、水花生为主,,且水花生与过江草对水中氮污染物具有很强的吸收能力。野外调查的沟渠Simpson 指数差异较大,即各沟渠的物种优势度具有明显差别,且沟渠内的优势物种相对较多。川中丘陵区野外调查的沟渠中植物群落中植物分布相对均匀。优势种不明显的沟渠均匀度较大,而优势种比较明显的沟渠均匀度则比较小。由于调查时期为植物生长茂盛时期,故川中自然沟渠生物量与植被覆盖度也相对较高。 (2)三种不同类型定点沟渠 本实验选取了盐亭县万安流域三条不同类型的沟渠进行定点观测。按沟渠的水流来源划分,沟渠类型分别为农田源头沟渠、村镇污水排放沟渠、农林复合排水沟渠。同时在每条沟渠设置干湿交替、间歇滞水、常年淹水区三种截面,村镇污水排放沟渠选取了四个采样点,农田源头沟渠选取了六个采样点,农田排水沟渠选择了四个采样点。沟渠采样点设置如下:农田源头沟渠1,,2号点为干湿交替区、5、6号点为间歇滞水区、3、4号点为常年淹水区。而村镇污水排放沟渠1号点为干湿交替区,2、3号点为间歇滞水区,,4号点为常年淹水区,陈家湾1,,2号点为干湿交替区,,3号点为间歇滞水区。4号点为常年淹水区,每一区域都同时设置有植株和无植株作为对照组。 不同类型沟渠反硝化能力有差异。村镇排水沟渠反硝化效率最大,其次为农田源头沟渠,农林复合沟渠,但农田源头沟渠与农林复合沟渠又因淹水条件不同存在些许差异。就整体情况而言,村镇排水沟渠反硝化势比较高,其反硝化速率变化范围 0.36~34.64 μg N2O-N?m-2?h-1(以N计,下同)。农田源头沟渠反硝化速率变化范围在0.01~3.01 μg N2O-N?m-2?h-1之间,农林复合沟渠反硝化速率变化范围在0.04~3.98μg N2O-N?m-2?h-1。同时农林复合沟渠与村镇排水沟渠的反硝化速率变化趋势随季节变化趋势一致,且村镇排水沟渠全部观测时间段的反硝化能力明显高于农林复合沟渠全部观测时间段的反硝化能力。 农林复合沟渠常年淹水区域反硝化N2O 的排放速率在整个试验期均显著高于农林复合沟渠干湿交替区域以及农林复合沟渠间歇滞水区 (前者平均分别为后三者的4.64、3.25、1.67倍)。其中农田源头沟渠干湿交替区1号点与2号点N2O 排放速率的变化趋势波动较大。农田源头沟渠常年淹水区3号点与4号点N2O 排放速率的变化趋势基本一致呈波动性,农田源头沟渠干湿交替区5号点与6号点N2O 排放速率的变化趋势存在一些不同,但基本趋势相似,呈波浪状,村镇排水沟渠常年淹水区域4号点N2O 的排放速率在整个试验期均显著高于村镇排水沟渠干湿交替区1号点区域(前者平均为后者的4.14倍),同时高于村镇排水沟渠间歇滞水区2号点区域、3号点区域(前者平均为后两者的3.12、1.79倍),且其差异达到显著水平(P<0.05)。 村镇排水沟渠植被段总氮去除量,季节平均植被段总氮去除量为15.43 g/d。其变异系数为104%,变异系数较大。生态沟渠植被段总氮去除量取决于生态沟渠氮素来源以及沟渠内水流流量变化差异较大。在2014年4月5 日达到最大值45.697 g/d,,同时在4月12日降至最低值 0.636 g/d。而生态沟渠植被区段反硝化平均去氮量为0.006405 g/d。其变异系数为38.2%,变异系数较小。生态沟渠植被段反硝化脱氮量主要取决于反硝化细菌,温度等变化较小因素。2014年8月26日达到最大值0.01246 g/d,,同时在4月12日降至最低值 0.00287 g/d。生态沟渠季节平均植被段反硝化去氮率为0.02123 %。其变异系数为190%。排水沟渠常年淹水区段反硝化去氮量与间歇滞水区反硝化区氮量均值均高于村镇排水沟渠干湿交替区反硝化区氮量(前两者分别为干湿交替区反硝化脱氮量的4.14和3.63倍)。说明季节积水的环境条件会有助于反硝化去氮比率的升高。 (4)影响因素 沟渠内有无植被两种不同对比之下的反硝化速率范围差异明显,有植被反硝化速率远大于无植被。大型植物可以通过间接和直接的方式影响反硝化率。首先,大型植物表面生物膜直接提供了反硝化发生的场所;其次,植物能通过吸收和释放作用间接改变养分浓度,氧气浓度,pH,以及沉积物和水体中的有机碳含量。沟渠各点有植株区域反硝化速率与沟渠各点相对应无植株区域的反硝化速率之差t值均达到显著差异水平,且r值均小于0.05达显著差异水平。同时各点有植株区域的反硝化速率与其对应的无植株区域的反硝化速率变化趋势有着较强的一致性。 村镇沟渠氮污染来源除了自然降雨之外还有居民生活污水,污染物底物浓度较大,故村镇排水沟渠反硝化速率>农田源头沟渠反硝化速率>农林复合沟渠反硝化速率。干湿交替区各点有植株区域具有显著性差异。间歇滞水区中村镇排水沟渠反硝化速率(5.50 μg N2O-N?m-2?h-1)>农林复合沟渠反硝化速率(1.34 μg N2O-N?m-2?h-1)>农田源头沟渠反硝化速率(0.62 μg N2O-N?m-2?h-1)。常年淹水区中村镇排水沟渠反硝化速率(13.32 μg N2O-N?m-2?h-1)>农林复合沟渠反硝化速率(2.22 μg N2O-N?m-2?h-1>农田源头沟渠反硝化速率(0.68 μg N2O-N?m-2?h-1)。 水体氮含量,沉积物氮含量与沉积物有机碳含量与沟渠反硝化潜势并无确定的线性关系。
Other AbstractNitrogen is one of the most important nutrient limiting factors of agricultural production,, and also the growing factor of the environmental pollution.The number of reactive nitrogen which came into the biosphere has considerably more than the quantity of the natural ecological system biological nitrogen fixation. Excessive reactive nitrogen came into the ecosystem,, destroyed the material balance,, and may lead to serious environmental problems. We had invested more than tens billions to nitrogen pollution controlling,, but there is little effect on the improvement of the eutrophication status,, and the situation of eutrophication is still heavying. Not only industrial pollution aggravate gradually,, but also agricultural nitrogen pollution including decentralized breeding pollution,, agricultural pollution rural sewage pollution,, soil erosion,, become more heavier than before. In the nitrogen cycle,, the denitrification process makes the fixed nitrogen go back to the atmosphere again in the form of N2. It seems to play the role of a closed the global nitrogen cycle,, and plays a pivotal role in the biosphere nitrogen cycle. Therefore,, denitrification—the process of land biological effectiveness of nitrogen loss,, is considered to be effective recovery and supply process in the form of N2. But in mountainous region,, the ditches come throμghout all landform mountainous region,, and what it composes is transporting corridor of pollutants which have considerable intercept effect. The ditch system mainly intercept losing nitrogen throμgh adsorption of sediment and biological transformation. In Mountainous area of our country,, especially in hilly area in Sichuan,,the drainage ditches,, connect agricultural drainage,, rural waste water with the rivers and lakes as the important passage. As an important channel of pollutants transportation,, the ditches not only have the function of transport,, but also good trench system can do a favor with reducing pollution load,, purificating water. Denitrification is probably the important way of the removal of water nitrogen in Sichuan basin. But,, for the lack of research of the denitrification mechanism,, and the contribution of Sichuan basin ditches denitrifying nitrogen's to the trench of nitrogen pollution removal is unclear. Since the Sichuan basin is located in the upper Yangtze river hinterland,, the improvement of the reactive nitrogen removal effect in the Sichuan basin ditche,, plays an important role in the reduction of reactive nitrogen input into the upper Yangtze river surface water,, and the great significance in the protection of water environment in Yangtze river basin. This paper experiment scheme is divided into two parts: one is investigation and experiment in the upper typical hilly area in Sichuan basin,, the second is fixed observation experiment of different types of ditches in the upper typical hilly area in Sichuan basin. The main research results and conclusions are as follows: (1) Investigation and experiment in the upper typical hilly area in Sichuan basin: the TN’s content of all the ditches water are all higher than the fifth requested water standard of national surface water of 2.0 mg/L,, which means severe pollution. And there is 9.72% of the water investigation’s content of TN more than 10 mg/L. The average TP content of the surveyed ditch water is below the national average surface water standard of 0.2 mg/L. However,, the water content of TP about 68.06% of the investigation sites is more than the standard of the eutrophication of 0.02 mg/L,, and the water content of TP about 31.94% of the investigation sites is higher than 0.2 mg/L. Some site’s TN content are even more than the fifth requested water standard of national surface water of 0.4 mg/L. The growth and decline of the phosphorus in the water are controlled by adsorption and precipitation mechanism,, and it could be the reason of coefficient variation of phosphorus concentration of the ditch water,, especially coefficient variation of the particle phosphorus concentration. Usually the rate of transformation of NH4 + into NO3 - in the environment is faster than organic nitrogen mineralization rate,, and total nitrogen is mainly composed of nitrate nitrogen. The ebb and flow of the phosphorus of the sediment in the upper typical hilly area in Sichuan basin is mainly in phosphorus particles state,, and deposites in sediments. And soluble phosphorus is rarely existing,, and phosphorus in the sediment is relatively stable. The ammonium nitrogen in the water is vulnerable to become nitrate nitrogen oxide,, and its variation coefficient is larger. The wetland plant biotype distribution of the upper typical hilly area in Sichuan basin because of the different factors such as altitude,, slope has some variation. The zonal vegetation is temperate meadow plants,, and mainly formated the community of entadae -stem,, alternanthera philoxeroides and so on. (2) The fixed observation ditches in the upper typical hilly area in Sichuan basin.: There are differences between the different types of ditch about the denitrification ability,, and town drainage ditches’ denitrification potential is strongest,, followed by agricultural ditches,, agroforestry ditches,, but agricultural ditches and agroforestry ditches has some differences because of flooding different conditions . In terms of the overall situation,, the town drainage ditches’ denitrification potential is highest,, and average denitrification rate ranged from 0.36~34.64 μg N2O-N?m-2?h-1 as turn(in N,, similarly hereinafter). Farmland ditches’ denitrification rate range from 0.01 ~ 3.01 μg N2O-N?m-2?h-1. And the agroforestry ditches’ denitrification rate ranged from 0.04 ~ 3.98 μg N2O-N?m-2?h-1. And the denitrification rate change trend of agroforestry ditch and town drainage ditch are changing similar with the seasons change trend. And town drainage ditches’ denitrification ability of observation period was obviously higher than that of agroforestry ditch of all observation period. The denitrification of the 1 zone and the 2 zone in dry-wet alternate zone of farmland ditches change volatile. The denitrification of the 3 zone and the 4 zone in perennial flooded zone of farmland ditches are almost the same changing trends of N2O emission rate volatility. The denitrification of the 5 zone and the 6 zone in dry-wet alternate zone of farmland ditches’ change trend of N2O emission rate has some different,, but the basic trend are similiar,, like a wavy structure. The denitrification of the 4 zone in perennial flooded zone of towns drainage ditches were significantly higher than that of the 1 zone in dry-wet alternate zone of towns drainage ditches changing trends of N2O emission rate volatility during the trial period(the former as an average of 4.14 times than the latter). And at the same time higher than that of towns drainage ditches the 2 zone and the 3 zone in intermittent delay watershed of towns drainage ditches (the former as an average of 3.12 and 1.79 times in turn),,and the differences reached significant level (P < 0.05). The denitrification of the 4 zone in intermittent delay watershed zone of agroforestry ditches were significantly higher than that of the 1 zone and the 2 zone in dry-wet alternate zone of agroforestry ditches and 3 zone in intermittent delay watershed of agroforestry ditches changing trends of N2O emission rate volatility during the trial period(the former as an average of 4.64,, 3.25,, 1.67 times respectively than the latter). The vegetation section’s total amount of nitrogen removal of town’ s drainage ditches,, and seasonal average amount of vegetation section of total nitrogen removal is 15.43 g/d. The variable coefficient was 104%,, and the variation coefficient is larger,, mainly due to ecological vegetation section of total nitrogen removal depends on the amount of ditch nitrogen sources of towns drainage ditches and different water flow rate. On April 5,, 2014,, at the same time it achieved the maximum of 45.70 g/d,, and on April 12,, dropped to the lowest 0.64 g/d. And ecological vegetation section denitrifying nitrogen on average came to 0.01 g/d. The variable coefficient was 38.2%,,and the variable coefficient is small. The denitrifying nitrogen of ecological vegetation section mainly depends on smaller factors such as the amount of denitrifying bacteria,, temperature changes. In Aμgust 26,, 2014 achieved the maximum of 0.01 g/d,, and April 12 dropped to the lowest 0.00 g/d. The denitrifying nitrogen removal rate of town drainage ditches’ average vegetation section of the season was 0.02%. The coefficient of variation is 190%. The denitrifying nitrogen removal of perennial flooded zone of town drainage ditches and the denitrifying nitrogen removal of in intermittent delay watershed of town drainage ditches all significantly higher than that of in dry-wet alternate zone of town drainage ditches (the former as an average of 4.14 and 3.63 times respectively than the latter). (3) The influencing factors: during the monitoring period the denitrification rate were quite different between the vegetation with the none vegetation. During the monitoring period,the differentials between the denitrification potential of vegetation drainage ditch with the corresponding the denitrification potential of no vegetation drainage ditch were t value level, and the r value is less than 0.05 significant difference level. At the same time,, the denitrification rate of each point without a plant area and of the corresponding denitrification rate of each point with a plant area’s changing trend has a strong consistency. ⑷Influencing factor The denitrification potential of town ditch in each area was greater than the other two types of channels.The denitrification rate of regional towns drainage ditches > the denitrification rate of farmland ditches> the denitrification rate of agroforestry ditches. The denitrification potential of all sites of vegetation zone in dry-wet alternate zone have significant differences,, with statistical significance. Termittent delay watershed zone : denitrification rate of drainage ditches in the town (5.50 μg N2O-N?m-2?h-1) > denitrification rate of agroforestry ditches (1.34 μg N2O-N?m-2?h-1) > denitrification rate of farmland ditches (0.62 μg N2O-N?m-2?h-1). Perennial flood watershed:denitrification rate of drainage ditches in the towns (13.32 μg N2O-N?m-2?h-1) > denitrification rate of agroforestry ditches denitrification rate (2.22 μg N2O-N?m-2?h-1) > denitrification rate of farmland ditches s (0.68 μg N2O-N?m-2?h-1). There is no definite linear relationship with nitrogen content of water,, nitrogen content of sediment ,, organic carbon content of sediment with denitrification potential of the ditches.
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/14177
Collection山地表生过程与生态调控重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
赵原. 川中丘陵区排水沟渠反硝化脱氮效率特征[D]. 北京. 中国科学院研究生院,2015.
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