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题名: 流域人类活动养分输入及其对河流氮磷通量的影响
作者: 张汪寿
学位类别: 博士
答辩日期: 2016-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 李叙勇
关键词: 淮河流域、人类活动净氮/磷输入、富营养化、城市化、农业生产 ; Huai River Basin, net anthropogenic nitrogen & phosphorus inputs, eutrophication, urbanization, agricultural production
学位专业: 生态学
中文摘要:        生态系统中氮磷养分的过量输入是导致流域水体污染及水生态破坏的重要原因。近几十年来,随着社会经济的快速发展,人类活动的不断增强,大量的氮磷通过化肥输入、大气沉降、食品输入、污水排放等途径进入生态系统,导致生态系统氮磷输入量不断攀升,并最终引起水体富营养化、生物多样性降低、地下水污染等一系列生态环境问题。
      为了实现有效的流域养分管理,本文以淮河流域为研究区,系统分析了1990年以来人类活动影响下的流域氮磷养分输入及其对河流氮磷通量的影响。首先在方法层面构建了区分点源和分散源的人类活动养分输入的估算体系,评价了淮河流域氮磷输入的时空动态,揭示了其输入变化的社会驱动因子;随后量化了河流氮磷通量对人类活动的响应关系,探讨了影响响应关系的因素;最后采用面板数据和回归模型,解析了各输入源对河流养分污染的贡献,模拟了未来情景下河流养分通量的动态变化。本研究主要阐述以下三个科学问题:当前生态系统氮磷输入快速增加最主要的推动力是什么?河流氮磷输出与流域人类活动养分输入是否存在定量的响应关系?如何基于输入输出的响应关系来实现流域氮磷污染的预测?并得出如下结论:
    (1)淮河流域是中国乃至世界范围内氮磷输入强度最大的流域之一,氮磷输入量分别为27000 kg N km-2 yr-1和2800 kg P km-2 yr-1,分别达到全球平均水平的17倍和30倍以上。氮输入方式主要以人类活动分散源输入为主,点源输入仅占总输入量的2%左右。90%的氮磷输入都来源于化肥施用、大气沉降和食品/饲料净进口。1990~2010年期间,氮磷输入量增幅较大,2010年氮磷输入量均达到1990年的1.5倍以上。粮食增产和稳产的需求是导致氮磷输入急剧增加的首要推动力,快速城市化并没有加速氮磷的总量输入,但会使得生活污水排放和大气氮沉降输入量的增加;
    (2)受纳水体与流域物质输入表现出了较明确的响应关系:人类活动输入的氮中仅有1.8%~4.5%左右会进入水体。与世界上其他流域相比,淮河流域的总氮输出比要远低于全球(25%)和美国流域(24%)的均值。这种低的河流氮的输出比主要与流域高强度水资源开发利用、高密度闸坝水库拦截等作用相关;在淮河上游源头流域中,人类活动输入的磷中约有3%会污染水体,该值也显著低于美国的流域(6%)。这主要是淮河流域80%以上的磷输入来源于化肥施用,其流失受植被拦截和土壤吸附的影响,大多被截留在地表;此外,流域坡度、径流量和土地利用类型等因素均会影响人类活动氮磷的流失和迁移;
    (3)构建的面板数据模型可解释81%的河流氨氮通量的时空变异,模型结果显示人类活动分散源输入是当前河流氨氮通量的主要污染来源,贡献率达58%;点源氮排放次之,为33%;剩余为自然输入贡献(9%)。构建的线性回归模型可解释67%的河流磷通量的空间变异,结果显示化肥施用仍然是当前河流磷负荷的首要来源。在未来,随着城镇化水平的进一步提高,需重点提升城市生活污水的处理率和排放标准,还需要大力推广化肥的减施增效技术,改善种植结构,从而较大程度减少流域氮磷养分输入对水体的影响。
英文摘要:        Increasing nitrogen (N) and phosphorus (P) inputs to ecosystem has became an issue of global concern, resulting in a series of ecological and environmental issues. Human activities strongly influence the N & P loads to watersheds in a number of different ways, for example through fertilizer application driven by increased agricultural activities, or through point-source discharge as the result of increased industrial and domestic emissions. Increased nutrient (i.e., N & P) input to watersheds is often accompanied by a high load of nutrient into the river system and other associated problems including eutrophication, reduction in biodiversity and water quality deterioration.
      In order to effectively achieve watershed N & P management, we carried out our research in the Huai River Basin (HRB) with the overall aim of understanding the variabilities of anthropogenic N & P inputs since 1990, and their corresponding roles in riverine pollution. Firstly, we differentiated the common “Net Anthropogenic Nitrogen Input” (NANI) methodology into two parts: point sources and non-point sources, and interpreted the driving forces behind the rapid increase of these inputs; Then, we investigate the impact of anthropogenic nutrient inputs on riverine nutrient fluxes and determine the potential influential factors of riverine nutrient export; And finally, panel data model and regression model for predicting riverine nutrient flux was proposed to determine the contributions of individual sources and simulate the possible changes in riverine nutrient exports using scenario analysis. Overall, three questions were answered by this study: 1) which is the driving force behind the rapid increase in N & P inputs? 2) Does N & P levels in receiving rivers was related to anthropogenic inputs? 3) How can we predict riverine nutrient fluxes based on the relationships between anthropogenic inputs and riverine exports?
      The main conclusions are presented as follows:
       (1) Huai River Basin was recognized as a region with one of the highest anthropogenic N inputs, as well as anthropogenic P inputs, across the world. Multi-year average (2003-2010) inputs of N & P to the watershed are 27000 kg N km-2 yr-1 and 2800 kg P km-2 yr-1, respectively. The values were separately 17 and 30 times the average intensity of N & P inputs reported for the global. Non-point sources comprised about 98% of total N input and only 2% of inputs are directly added to the aquatic ecosystem as point sources. Fertilizer application, atmospheric deposition and imported food & feed were the largest sources of new N and P to the HRB, comprising about 90% of net anthropogenic N &P inputs. During the period 1990-2010, both of the average growth rate of nitrogen and phosphorus input have reached higher than 50%. Further results suggested that the corresponding driving-force behind increasing N & P inputs may be attributable to food production, while rapid urban development did not accelerate the nitrogen input as expected. However, rapid urban development could lead to more severe atmospheric deposition, as well as more urgent food demand, which could pose greater risk on aquatic systems.
      (2) Riverine N fluxes have shown a close relationship with anthropogenic N inputs, with an average 1.8~4.5% and 0.9% of NANI exported as riverine total N and ammonia-nitrogen (AN) flux, respectively. While, our estimate is far below the average total nitrogen export ratio globally (25%) and for US watersheds (24%). The low values of percent TN export in the HRB were explained by their great number of impoundments or water bodies, and high consumption of water resources (containing N). Riverine total phosphors flux in this watershed also exhibits positive relationships with anthropogenic P input. However, this relationship was just appeared in the headwater watersheds, with an average 3% of NAPI exported as riverine TP flux. The proportion of NAPI exported in rivers from the HRB are lower than that of US watersheds (5.9%). The reason behind the regional discrepancy may be due in part to the difference in NAPI composition. In most of US watersheds considered, the contribution of non-food P inputs to NAPI was obviously higher than that in HRB. However, these P inputs usually took the form of point source inputs (e.g., urban sewage systems), which would show smaller retention and a higher ratio of NAPI entering rivers. In addition, watershed slope, streamflow, and landuses may influence the extent of export of riverine N and P fluxes from anthropogenic sources.
      (3) A panel data regression model of riverine AN exports as an exponential function of N inputs and a power function of annual water discharge accounted for 81% of the variation in annual ammonia-nitrogen fluxes over space and time. Model results suggested that anthropogenic non-point-scource N input is the dominant source of AN export (contributing about 58% of AN export), followed by point-source N input (33%) and natural sources (9%). Application of this model to three scenarios suggests that future N pollution will be inevitablely deteriorated if the current urban environmental management and investment are not significantly improved. A linear regression model was also constructed to predict riverine total phosphorus exports, explaining 67% of of the variation in multi-year averaged phosphorus fluxes. Model results suggested that fertilizer application was the major contributor of riverine phosphorus fluxes. In order to alleviate N & P pollution, more effort should focus on reducing fertilizer application and improving sewage treatment rate and N & P removal rate of the current sewage system. Thus, riverine N & P pollution could be expected to be effectively controlled.

内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/37054
Appears in Collections:城市与区域生态国家重点实验室_学位论文

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Recommended Citation:
张汪寿. 流域人类活动养分输入及其对河流氮磷通量的影响[D]. 北京. 中国科学院研究生院. 2016.
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