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题名: 多水塘景观体系中磷污染物的传输迁移和能量流动过程
作者: 单保庆
学位类别: 博士
答辩日期: 2000
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 尹澄清
关键词: 非点源污染 ; nonpoint source pollution(NPS) ; 多水塘系统 ; the multipond systems ; 景观格局 ; landscape pattern ; 径流控制 ; surface runoff control ; 降雨模拟 ; rainfall simulation ; 表面径流 ; surface and subsurface flow ; 壤中流 ; phosphorus ; 连续型径流 ; the continuous and discontinuous runoff ; 间为型径流 ; watershed ; 流域
中文摘要:       本文以安徽省肥东县巢湖北岩中庙附近的六叉河流域为野外实验点,于1998和1999两个水文实验年,在流域流动尺度上,研究了流域多水塘系统的景观格局,系统对流域水文一径流的控制效应模式,系统径流过程中的空间能量学变化以及磷污染物在多水塘系统中的传输迁移过程;人工模拟了源区磷污染物产生、迁移动态;并对多水塘系统的磷截留控制机制进行了总结。研究结果发现:(1)多水塘系统是一类以水塘为点渠道为线的复合网状人工湿地生态系统。六叉河流域面积691.6ha,多水塘系统43.2ha,占6.2%;水稻田是流域主要土地利用类型。水田与水塘的面积比例9:1。系统水塘总数为193个,面积范围介于100-10000m~2。塘均深为1.5。塘边周长为31,500m,塘容总量达5.72 * 10~5m~3。沟渠系统十分发达,渠道总长达23,380m。平均塘一斑块面积为1976m~2;塘一斑块密度是28个/平方公里;流域渠道-线密度为33.8m/ha;斑块边缘密度为45.5m.ha,水塘-斑块的分维数为1.40,景观分离度为4.73,系统网络γ指数为0.32,景观类型多样性指数为0.591。流域水陆交错带比例、景观系统破碎度以及系统塘渠网络程度都比较高,但景观类型多样性程度较低。(2)流域磷污染物产输具有显著的源区差异性。雨强0.79mm/min的降雨模拟实验表明,村庄是流域源区磷污染物的最大输出者,蔬菜地次之,水稻田、油菜地和森林坡地群落则少的多;磷输出以悬浮态总磷(78.5%-94.9%)为主,溶解性总磷(3.1%-19.6%)和正磷酸盐(1.2%-2.9%)所占比例较低。村庄和旱地是流域磷的潜在高流失区,水稻田次之,林地流失风险最低。旱地表层土壤具有明显的壤中流和磷迁移现象。壤中累积输出的径流量低于表面流。农作物生长分布能促进壤中流,减缓表面流过程。(3)研究发现多水塘系统能有效控制流域水文-径流过程,系统产生两种径流模式:连续型径流和间断型径流。流域降雨量同潜在的系统径流模式之间的关联程度很高。根据几十次降雨观察统计,降雨量<25mm时,流域下垫面基本不产流;25 ~ 60mm之间时,流域产流,为间断型径流,全流域不出现表面水输出峰值,仍保持基流。降雨量>60mm时,为连续型径流。连续型径流决定着整个流域的年际磷输出量。98年5月1日连续流事件中,鲍家塘子流域的总径流产量5847.7m~3,输出水量993.4m~3。系统的水截留率为83.0%,TP93.9%, DP90.9%, SS94.9%。98年6月29日间断型径流事件中,整个子流域产流1840.6m~3,系统没有表面水输出,TP、DP和SS的截留率拉近100%。(4)多水塘使得流水动能多次沉降,两种径流类型的水流速度入塘后在较短距离内都发生显著下降。从V_1(0m)至V_3(6m),连续型径流从24.5cm/s下降到1.4cm/s,间断型径流从34.8cm/s下降到0.8cm/s。(5)系统景观结构影响着空间传输,不同径流形式的磷污染物浓度空间变化差别很大,水塘类型对污染物种类的瞬间滞流效应不一。在98年5月1日连续流事件中,单一田塘TP,DP和SS的平均递减率为36.1%, 12.8%和33.6%;旱塘则为34.1%m 15.8%和42.4%。98年6月29日的间断流事件中,单一田塘的磷污染物浓度递减率为100%,旱塘为:TP44.8%, DP41.1%和SS64.7%。水塘对颗粒态污染物的瞬间沉降作用非常显著,而溶解性磷则低得多。(6)由于多水塘系统的存在,流域系统水分循环率非常高。98年整个流域水田系统的单次灌溉量为3.12 * 10~4m~3,年循环总量为1.22 * 10~5m~3。99年的次灌溉循环量为2.65 * 10~5m~3,年循环总量1.33 * 10~6m~3。每次灌溉使水塘的贮水能力约提高50%。水塘能有效地沉降颗粒态磷。整个多水塘系统的TP年沉积总量7016kg,沉积物为14.38 * 10~6kg。抽水灌溉使得系统大量的磷返回源区。98年TP再循环总量78.1kg,99年82.5kg,溶解态磷是主要的再循环形式。通过水生植被的吸收转化,每年约有62.11kg的磷转移到植物系统,再从大系统中去除掉。
英文摘要:       The landscape pattern of the multipond systems, the flow pattern of surface water in the systems, the kinetic energy change of the water in the flowpath, and the control mechanisms of phosphorus by the system in an experiment watershed located on the northern bank of Chaohu Lake, China, were studied during the two hydrological years (1998 and 1999). The results showed as following: (1) Liuchahe watershed has an area of 691.6ha with a typical landscape of the multipond systems (43.2ha). The ricefield is the main landuse type, and the area rate between the ricefield and the ponds is 9:1. In this watershed, there are 193 artificial ponds ranging with their size from 100 to 10,000 m~2 and a mean depth 1.5m. The total perimeter of all the ponds is 31, 500m, and the pond volume is 5.72 * 10~5m~3. The landscape pattern characteristics of the systems are as following: mean pond-patch area 1976m~2, pond-patch density 28/100ha, ditch-line density 33.8m/ha, pond-patch edge density 45.5m/ha, the fractal number of the ponds 1.40, the net-connectivity(γ) 0.32, and the landscae diversity index 0.591. There is a high ratio of inland/water ecotone. (2) The results of an artificial simulation showed that, village was the largest P-pollutants source among the five landuse types. Vegetable field was the second largest and there were much less P loads from rice fields and forest. Particulate phosphorus was the main form of phosphorus exported (78.5% - 94.9%). P-pollutants can be transported through subsurface flow, though the mass was much less than surface water. (3) The multipond system can effectively influence hydrological process of watershed and control the water export. It generally produces two surface runoff types in the watershed-scale: continuous runoff and discontinuous runoff. Statistics in Liuchahe watershed shows that when precipitation between 25 to 60mm during a 24-h period, surface runoff generation was discontinuous; and when precipitation surpasses 60 mm, the surface runoff was continuous. In the continuous runoff events of May 1, 1998, the retention of water, TP, DP and SS by the system were 83.0%, 93.9%, 90.8% and 94.9% respectively. In a discontinuous runoff on June 29, 1998, there was no export through surface water, the P-pollutants were retained in the system completely. (4) When runoff passes through the ponds, the kinetic energy decreases significantly. During the continuous runoff on May 1, 1998, decreases of the flow rate in the three Bottom Ponds of Baojiatang subwatershed were 85.0 - 95.0% in a distance of 6 m. Concentration of TP, DP and SS also decreased at all the ponds. (5) Irrigation activity was an important way for water and nutrients recycling within the watershed. One irrigation event can improve 50% storage capacity of ponds. The multipond systems retard water flow process and made flow velocity decrease sharply, this improve sedimentation of particulate materials in the systems. Sediments and phosphorus sinked into ponds bottom were 14.38 * 10~6 and 7016 kg annual year. A lot of aquatic plants in the systems also play an important function, and phosphorus removal per year through this way was 62.11kg.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/34937
Appears in Collections:环境水质学国家重点实验室_学位论文

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Recommended Citation:
单保庆. 多水塘景观体系中磷污染物的传输迁移和能量流动过程[D]. 北京. 中国科学院研究生院. 2000.
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