Three Gorges Reservoir and potential environmental problems of pollution

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Abstract With the rapid economic development, environmental problems caused by the Three Gorges reservoir area of the concerns. Summarizes the Three Gorges Reservoir status of environmental pollution, and analyze its potential ecological environment, vegetation and fisheries issues and proposed implementation of the recommendations of ecological and environmental protection.

Keywords: Three Gorges Reservoir; fluctuating zone; ecological environment; pollution; potential problems; suggestions

The fluctuation of water level fluctuation zone with known, is leaving the reservoir around the seasonal water level fluctuation periodically flooded land exposed in a special area in the water. It is the aquatic ecosystems and terrestrial ecosystems in the transition lots, is a special type of wetland ecosystem [1]. in artificial control, the Three Gorges Reservoir's water level fluctuation of velocity, amplitude and frequency was significantly different from the natural river, increasing the instability of fluctuating zone, but as the economy The rapid development of industrial pollution, sewage on the impact of Gorges Reservoir gradually increased. strengthen the fluctuating zone of ecological protection area to play its role in the Three Gorges Project is the prerequisite and foundation, but also a necessary condition for sustainable development in the reservoir area.

1 Pollution
1.1 Industrial Pollution
Three Gorges Reservoir pollution is the most important lead and cadmium pollution [2], which mainly come from industrial waste water, waste residue. Lead to make soil fertility degradation, soil decreased, so that crops can not effectively grow smoothly. In addition, by crop uptake, these harmful elements will be transmitted through the food chain in the ecological balance in the body. cadmium in the environment with a stable, easy to remove accumulation and the characteristics of the human body through the food chain accumulation of chronic poisoning. cadmium contamination may eventually lead to " Itai-itai disease. "
Studies have reported a variety of ways with the Three Gorges Reservoir Evaluation of heavy metal pollution, the results show that the main factor for cadmium pollution, ecological risk factors of the order of Cd> Zn> Pb> Cu> Cr, the potential ecological risk factor of the order of Cd> Pb> Cu> Zn> Cr, with a lot most of the cross section fluctuation a moderate potential ecological risk [3,4].

1.2 Sewage Pollution
Since the vicinity of Three Gorges Reservoir area residents with improved living standards, life in the vegetables, washing clothes, flushing toilets and other emissions generated by the gradual increase in water, causing water to the fluctuating environmental pollution with the water gradually increased. To Gorges Reservoir region of rapid economic development, we must speed up the Gorges Reservoir area sewage treatment infrastructure, reduce pollutant emissions [5].

1.3 The impact of reservoir water
With the formation of fluctuating reservoir water due to the seasonal water level fluctuation, which would make the soil drawdown zones by the many negative effects, mainly the reservoir water pollutants through a series of physical changes and chemical changes constantly accumulation in the soil, and then the physical properties of soil influence. soil is flooded, the soil of nutrients, pollutants will be dissolved and adsorption in the water, it is a complicated process. submerged in contaminated soil matter emission reached the maximum at day 1, about 10d in 80% of the total release of 90%, over time the growth of emissions to less and less. the water and some solid particles of organic matter through physical or after a chemical change to the soil, under certain conditions in the soil can add organic matter, thereby improving soil properties. Sewage also has nitrogen, phosphorus and other organic elements, to a certain extent, can also increase the nutrient content of the soil, maintain Fei Li. but in this case there are negative side is that when the accumulation of pollutants in the soil up to a certain extent, will cause Turang the composition, structure, properties and functional changes, resulting in soil contamination [6]. being soaked soil of planted crop yield was also lower than normal [7]. Water for the rock minerals and the release of nutrients, exercise, diffusion plays a vital role. and in different water conditions , rock differences in nutrient transport. According to test results show that 8% and 12% of water treatment and natural state of nitrogen, phosphorus and potassium release in comparison, the increase reached a significant level [8]. Therefore, the reservoir water will speed up the Gorges Reservoir nutrient release purplish rock, so a lot of nutrients transferred to the water, causing eutrophication of water bodies. Gorges Reservoir main soil types, purple occupies a large proportion of the soil, and purple poor soil and nutrients are fluctuating with a cause of low crop yields. seasonal water level fluctuations will increase the trend of soil erosion, the soil of nutrients to the water transfer [9].

2 potential problems
2.1 ecological environment
One easily lead to geological disasters. Most of the Three Gorges Reservoir steep terrain, poor stability of the bank formation, coupled with fewer people and more along the reservoir, human activities, environmental geological disasters in China-prone areas [10]. Three Gorges Dam After completion, the reservoir water storage capacity increased, bank on both sides of the rock periodically soaked in water to make drinking water has increased in Mountain Reservoir, resulting in reduced cross slope stability, and induce landslides, avalanches and landslides [11], severe threat to lives and property of Reservoir and reservoir safety. For example, the 1998 Yangtze River floods occur when the reservoir Yunyang in nearly 10 counties formed a collapse and landslide. resumption of normal water storage of Three Gorges Reservoir, the annual November to the following March 5-month high level, long soak river, together with the Three Gorges Reservoir in spring and summer water level in the 175,145 m gap near 30m, will definitely lead to a large area along the reservoir banks collapse, landslide led to the terrain variation [12]. The second is easy to epidemic outbreaks of epidemic disease. drawdown of water level fluctuation zone is the zone will be alternating between land and water pollution. low water, garbage, weeds and other pollutants remain in the fluctuating directly take; high water level, water flow is slow, difficult diffusion of pollutants [13]. these 2 environments are easy to cause a variety of related pathogens, bacteria breeding, especially in the summer under hot and humid environmental conditions, pollution is serious The fluctuating zone will be a variety of related bacteria, parasites, breeding sources and the dissemination of odors and odor to, and likely to lead to large-scale outbreak of the incidence and prevalence [14].

2.2 Vegetation problems
Producers of the ecosystem of plants, provide material for the source of energy for the entire system is based on stability of the system. Science is the optimal planting trees and grass with a fluctuating environment as a way to mitigate geological hazards and effective measures to better Vegetation play fluctuating socio-economic and ecological benefits. fluctuating function with a lot of vegetation and concrete can be divided into four functions: First, mitigation functions. Three Gorges Reservoir, the vertical distance of tens of meters of land were flooded and the reservoir bank slope sediments are mostly residual water content will reduce the stability of the increase, resulting in landslides and other geological disasters; lead to wet down the water level changes in causing the expansion of rock and soil, resulting in Reservoir instability. Second, the economic function. drawdown zone and post-maintenance planting trees and grass will need a lot of labor, provides many jobs. In addition, fruit trees, vegetable cultivation can generate income for farmers. Third, clean up the environment. Gorges Reservoir water, the flow slowed down, reduced diffusion capacity, decreased water self-purification capacity, increasing environmental pollution. some of the herbs can absorb some of the harmful substances in water, until a certain time to harvest, you can take pollutants out of reservoirs. Fourth, the landscaping features. vegetated with aesthetic value, can bring visual enjoyment [15]. At present, the Three Gorges reservoir area and support the many tributaries of the Bay Area into the mainstream of the library can use a larger fluctuation zone area. Therefore, fluctuating zone enough land can be used for vegetation protection.

2.3 Fisheries
Three Gorges Reservoir to the effective use of the lot with a number of tributaries flooded estuary region after the formation of "bellies" to form Bay, part of the water has been a certain degree of pollution, combined with meandering tributaries, water exchange by the "belly head" constraints in such waters for aquaculture, production methods are inappropriate or if the scale of production out of control, it is prone to eutrophication of local water pollution. Therefore, in the planning, implementation, fluctuating with the development of fisheries, the waters must be determined for all types of departments and regional water quality standards, careful assessment of different farming methods and the impact of production scale, to take certain technical measures to control pollution [16].

3 recommendations
Three Gorges Reservoir for a variety of ecological and environmental problems, should first point of fluctuating water with different shape, scope, spatial distribution, ecological state of the environment to carry out appropriate Research; fluctuating according to different regions of the natural geographical features with , ecological environment and the requirements of safe operation of the Three Gorges water conservancy project, fluctuating with the development and use of ecological and environmental protection planning, division of functional areas; and so as the Three Gorges Reservoir on land use and ecological protection of the guiding basis for future Research foundation. in industrial and agricultural production must be possible to reduce the emission of pollutants, encourage entrepreneurs to set up materials circulation, so that contaminants can be re-use as raw materials, bringing the regional environmental pollution have taken control as soon as possible and ecological restoration.

4 References
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[15] TRANSACTIONS ON, Yang DY, Xu Yonghui, et al. Three Gorges Reservoir vegetation ecological Engineering [J]. Soil and Water Conservation, 2006,26 (1) :42-43, 49.

[16] Chang-Qi, Ye Yuan-Tu, Liu Fanggui, et al. Gorges Reservoir Chongqing Gorges Reservoir FISHERIES [J]. Land and Natural Resources Research, 2000 (1) :51-54.

Links to Research Papers Download http://www.hi138.com