三峡库区网箱养鱼对周围水质的影响

Impact of Fish Cage Culture on Environmental Water Quality in Three Gorges Reservoir Region

以朱衣河二道河湾回水区网箱养鱼水质的现场监测结果为基础,采用综合营养状态指数法对网箱养鱼水域的现状进行了营养状态评价,并用污染物浓度等值线法进行了网箱养鱼对周围水质的影响分析。结果表明:网箱养鱼及其影响区的水体综合营养状态均为轻度富营养,水质污染程度为轻度污染,其综合营养状态变化总趋势为网箱养鱼区大于网箱影响区;网箱养鱼影响区的Chla浓度明显高于网箱核心区,其余污染物浓度的平面分布总趋势是由网箱核心区向网箱影响区由高向低变化;若以超河流背景断面浓度5%作为划定超背景污染带的标准,则朱衣河二道河湾网箱养鱼引起CODMn、NH3-N、TN、TP和Chla超背景的污染面积分别为35 000、22 500、23 760、54 000和16 000 m2,分别是网箱养鱼区面积(3 900 m2)的9、5.8、6.1、13.8和4.1倍。

Based on on-site water quality monitoring results in Zhuyi River Erdaohewan Backwater Zone, the nutrient state of fish cage culture water area was evaluated using index method. The impact of fish cage culture on environmental water quality was analyzed using pollutant concentration isoline meth- od. The results show that the synthetic water nutrient state in fish cages and their impact area is slightly eutrophic, the water quality is slightly polluted, and the total tendency of the synthetic nutrient variation in the fish cage culture zone is higher than that in the impact zone. The Chl-a concentration of the impact zone is significantly higher than that in the fish cage core zone. The total tendency of plane distribution of other pollutants concentration is higher in the fish cage core zone and lower in the impact zone. If the exceeded background concentration of 5% is used as the standard for background pollution zone, CODMn, NH3 -N, TN, TP and Chl-a background pollution areas induced by fish cage culture are 35 000 mE, 22 500 mE, 23 760 m^2, 54 000 m^2 and 16 000 m^2 respectively. They are 9, 5.8, 6.1, 13.8 and 4.1 times of fish cage culture zone area （3 900 m^2）.