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三峡库区水体中营养盐与浮游生物量分布特征 【作者】张晟 【导师】魏世强

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,m8m2G9jYM0三峡库区水体营养盐与浮游生物量分布特征水利论文*I&iD$edE#t2it

U7n R,y k RP*~0作者张晟导师】魏世强
D3y;iA$I3gT)r[0【作者基本信息】西南农业大学,农业资源利用,2005年,博士水利论文 nktL.T

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"g)a@{)[GZ0【中文摘要】 水体富营养化是普遍存在的生态问题。三峡水库于2003年6月正式蓄水,坝前水位保持在135m。成库后,水体由河流变为典型的河道型水库。过水断面增大,在上游流量不变情况下,流速自库尾至坝前逐渐减缓。当175m蓄水时,流速由2m/s降至0.25~0.5m/s,水流对污染物的输移扩散能力下降,在同样的排污方式,相同的排污负荷下污染混合区必将加大。成库后,水流速度减缓,大量泥沙沉积,水质变清,透明度增高,冬季水温升高、雾日减少,水面日照时间增加,有利于水生植物特别是藻类的光合作用,导致藻类的生长繁殖,增加了三峡库区水体发生富营养化的可能性。由于水文条件的改变,水生生态系统结构、功能必然受到一定程度的影响。三峡成库后,尚未见对水库蓄水后富营养化状况的相关报道。三峡水库135m蓄水后,部分次级河流的回水区已经出现水体富营养化现象,表明水体流速减缓后,容易导致水体富营养化的发生。水库初期蓄水至135m后,营养盐含量、分布规律和浮游生物变化对预测175m蓄水后水生生态变化具有重要借鉴意义。因此,分析三峡水库成库初期营养元素和生物量的分布特征对于深入研究三峡水库成库过程中营养盐动态变化及其与浮游生物的消长...更多的关联规律,预测库区水体富营养化的发展趋势,保护库区水质具有重要理论和实践意义。 本文采用实地采样分析的方法,通过对三峡库区16条主要次级河流和35座大中型水库富营养化研究,从大量数据中得到营养盐与叶绿素a含量的关系,预测了175m蓄水时,三峡水库干流、主要次级河流河口叶绿素a含量状况。利用河道富营养化QUAL2E模型,预测了乌江175m蓄水后营养盐与叶绿素a沿程分布特征。在此基础上,于2004年1月~2004年12月,通过对三峡水库营养盐及有机物的大量监测分析,得到营养盐、有机物和叶绿素a的分布特征。 三峡水库成库后,沿水库水流方向从上游朱沱至下游巫山,营养盐和有机物(除BOD外)在水平分布上无明显差异;上游区(朱沱、寸滩)和回水变动区(涪陵)营养盐及有机物垂直分布上也无明显差异。但通过对水库区(万州)多层次采样分析,BOD垂直分布有显著差异。三峡水库氮、磷浓度含量高,不同形态氮含量分别为:NH3-N浓度范围在0.12~0.17mg/L;NO2-N含量变动范围在0.018~0.036mg/L;NO3-N浓度范围在1.19~1.42mg/L;TN变动范围在1.60~1.82mg/L。TP含量范围在0.11~0.15mg/L。COD变动范围在2.6~4.0mg/L之间,BOD变动范围在0.80~1.28mg/L。总氮、总磷浓度值均超过水体发生富营养化的限制值,总氮、总磷比值在适宜藻类生长比值的范围内。通过对所有测点聚类分析结果表明,三峡水库营养盐、有机物有明显地域分布特征,即上游区和回水变动区相似,而与水库区有差别。通过对不同蓄水期三峡水库入口处营养盐浓度及流量的监测,假设上游营养盐排放保持现状,预测了不同蓄水阶段上游来水的营养盐输入状况。其中,135m蓄水,上游来水TN年  还原水利论文(x[z$U R%m Krv\

2LFGO!vF,P4Y K0【英文摘要】 Aquatic eutrophication is a prevalent ecological problem. The Three Gorges Reservoir started water storage in June 2003, and water level of the dam fluctuated around 135 meters. Since then, part of the Yangtze River became a typical channel reservoir, consequently, flow velocity of water in this area sharply decreased as hydraulic condition changed. Moreover, water level of the dam would finally reach up to 175 meters in 2009, and water flow velocity would decrease from 2 m/s to 0.25-0.5 m/s, which would seriously impair its transport and diffusion capacity for contaminants. With the same load of nitrogen and phosphor as well as the same discharge method, water quality of the Three Gorges Reservoir would definitely deteriorate. As another consequence, a series of factors resulted from damming, such as lower water flow velocity, higher transparence, depositon of suspended solid, higher water temperature, fewer foggy day and increased sunlight in winter, would be optimal for photosynthes...更多is of aquatic plant, especially algae, which could potentially lead to eutrophication. Therefore, the structure and function of local aquatic ecosystem would be influenced by changing hydraulic condition, however, few studies on eutrophication have been reported since the water storage of the Three Gorges Reservoir. As a matter of fact, eutrophication phenomenon has already occurred in backwater area of some tributaries, which indicated that low velocity of water flow might lead to eutrophication. Therefore, to investigate the distribution characteristics of nutrient and biomass of the Three Gorges Reservoir at the initial stage has significant meaning to further study on nutrient change characteristics in the process of water storage and its correlation between the growth of phytoplankton, forecast the potential trend of eutrophication in reservoir area, as well as protect the water quality of the Three Gorges Reservoir.By means of field examination and sampling, 16 major tributaries in the Three Gorges Reservoir area and 35 large reservoirs in Chongqing were studied. As a result, the relationship between chlorophyll a and phosphorus was obtained, and concentrations of chlorophyll a in both main stream of the reservoir and estuary of its major tributaries when water level reaches 175 meters were also predicted. Based on the QUAL2E model, distribution characteristics of nutrients and chlorophyll a in the Wu River after the implementation of 175 meters water level were predicted. Meanwhile, large scale investigation of nutrients and organic pollutants were carried out at 6 monitoring sites along the Yangtze River from January 2004 to December 2004, consequentially, distribution characteristics of nutrients, organic pollutants and chlorophyll a were obtained.After the water level reached up to 135 meters, no significant differences between nutrientsand organic pollutants in the horizontal distribution were detected except BOD, and so did nutrients and organic pollutants in the vertical distribution in upriver (Zhutuo, Cuntan) and backwater area (Fuling). While in reservoir area (Wanzhou), BOD appeared to be significantly varied along vertical direction. High concentrations of nitrogen and phosphor were detected in the Three Gorges Reservoir, for instance, the concentration of NH3-N ranged from 0.12 to 0.17 mg/L, and that of NO2-N, NO3-N ranged from 0.018 to 0.036, 1.19 to 1.42 mg/L respectively. The contents of TN (total nitrogen) and TP (total phosphor) varied from 1.60 to 1.82, 0.11 to 0.15 mg/L, respectively, while that of COD and BOD ranged from 2.60 to 4.0, 0.80 to 1.28 mg/L, respectively. Obviously, concentrations of TP and TN exceeded the eutrophication limits, and the ratio between TN and TP was right in the range which could boost algae growth. System clustering indicated significant regional distribution of nutrients and organic pollutants, namely the upriver area and backwater area, which were different from the reservoir area. Based on current situation, provided the discharge method of nutrients in the upriver stays the same, nutrient loads at different water levels were predicted. When the water level reaches 135 meters, TP load would be 788010 tons per year, and that of TN would be 89088 tons. The annually input loads of TP, TN would decrease to 696630 and 83199 tons respectively when the water level reaches 156 meters, whereas 403920, 57306 tons respectively at the water level of 175 meters.Relatively low concentrations of chlorophyll a, ranged from 0.50 to 3.81 mg/m3, were detected in the main stream to the reservoir. According to the OECD assessment standard, most of the data indicated oligotrophic condition. However, high chlorophyll a concentrations in the Daning River, ranged from 7.53 to 27.3 mg/m3, exceeded the limit for eutrophication. Meanwhile, 8 categories, 43 families, 99 genus, and 301 species (including mutations) of phytoplankton were found in this area. Diatom and green algae were the major species, which made up to 76.1% of all. Besides, 3 categories, 35 families, 76 genus, and 106 species of zooplankton were also discovered. Similar conclusions from the above 2 assessment method suggested all monitoring sites were slightly polluted.Based on chlorophyll a concentration, 12 monitoring sites of all 39 were classified as eutrophication category. Among the tributaries, no significant correlations between phosphorus concentration, transparence and chlorophyll a were exhibited. During the eutrophication period, concentrations of chlorophyll a in the Wu River ranged from 11.1 to 29.6/^g/L. Each part of the Wu River could be classified as eutrophication according to the OECD standard. On the other side, 22 out of 35 large reservoirs were in the state of eutrophication, which consisted of 62.9% of all. Moreover, 5 reservoirs were categorized as hyper eutropher (14.3% of all), 10 as middle eutropher (28.6%), 7 as light eutropher (20%), and another 12 as mestropher (34.3%), only 1 (2.9%) was  还原水利论文sbAt&vo-]

#X z1v'v2ph0【中文关键词】 三峡水库; 营养盐; 叶绿素a; 富营养化
$@v0K)YO0【英文关键词】 the Three Gorges Reservoir; nutrient ; chlorophyll a; eutrophication水利论文_ Y\K,cO~
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