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中文:南湾水库水质富营养化调查与评价
本研究调查了南湾水库水体的理化指标、浮游植物的种类组成和生物量,利用修正卡森指数(TSIm)、综合营养状态指数(TLI),浮游植物的种类多样性指数以及浮游植物的优势种等参数对南湾水库水体的富营养化状态进行了评价,并且跟踪调查了调整鲢鳙鱼种放养比例后对南湾水库水质指标及浮游生物的影响,以期为南湾水库的综合治理与合理开发提供理论依据。
1、南湾水库理化指标监测与富营养化状态评价
通过对南湾水库叶绿素a(Chla)、总氮(TN)、总磷(TP)、溶解氧(DO)、五日生化耗氧量(BOD5)、高锰酸盐指数(CODMn)、pH值、水温、透明度(SD)和水深等水体理化指标的调查,选择修正卡森指数和综合营养状态指数法对南湾水库水质的营养状况进行综合评价。南湾水库修正卡森指数的评价结果为TSIM = 59.03,已达到富营养化的标准;TLI(∑)= 54.75,达到轻度富营养化标准。
2、南湾水库的浮游植物与富营养化评价
调查了南湾水库浮游植物的生物量、种类组成,计算南湾水库浮游植物的多样性指数,从生物的角度来评价南湾水库的营养状况。结果表明,南湾水库浮游植物的生物量平均为4.337 mg/L,代表富营养化的指示种蓝藻为南湾水库浮游植物的优势种。浮游植物种类组成的Shannon-Weiner指数为3.45;Pielou指数(均匀度指数,E)为1.15;Simpson’s 指数(优势度指数,D)为0.84,表明浮游植物群落结构还是处于比较稳定的状态。从浮游植物的种类组成、优势种、生物量和种类多样性指数等指标来评价,南湾水库处于中营养到富营养的水平。
3、调整鱼种放养模式对南湾水库水质和浮游生物的影响
跟踪调查了鲢鳙鱼种的放养比例由20∶80调整为40∶60,鲢鱼的放养量由43.73g/m2增加到87.47g/m2,鳙鱼放养量由174.94g/m2减少到131.20g/m2, 对南湾水库水质和浮游生物的影响。研究结果表明调整鲢、鳙鱼种的放养比例后,南湾水库的水质得到了一定的改善,表现为COD、BOD和叶绿素a含量显著降低,透明度显著升高。另外,从浮游生物调查的结果来看,增大鲢鱼放养比例,降低鳙鱼的放养比例,对浮游动物的数量和生物量影响不大,但能显著降低浮游植物的数量和生物量,同时也大大降低了蓝藻在藻类群落中所占的比例及其生物量,有效地避免了水库蓝藻水华的爆发。
English:Evaluation and Investigation of Water Eutrophication in Nanwan Reservoir
In order to evaluate the eutrophication state of Nanwan reservoir, the physical and chemical indexes of the water body, species composition and biomass of phytoplankton in Nanwan reservoir were investigated. Modified Carlson index (TSIM), synthetic trophic level index, species diversity indexes and dominant species of phytoplankton in Nanwan reservoir were adopted in the eutrophication assessment. The effects of changing the ratio between silver carp and big head carp put in the reservoir on water quality and plankton were also investigated.
1. Physical and chemical index of water body in Nanwan reservoir and its eutrophication state assessment
Water quality indexes including chlorophyll a concentration, total nitrogen concentration, total phosphorous concentration, dissolved oxygen concentration, BOD5, CODMn, pH, temperature and transparency etc. were measured in this study. The modified Carlson index (TSIM) of Nanwan reservoir was 59.03, indicating that the water body arrived eutrophication. The synthetic trophic level index of Nanwan reservoir was 54.75, indicating that the water body arrived light eutropher.
2. Phytoplankton in Nanwan reservoir and eutrophication assessment
The biomass and species composition of phytoplankton in Nanwan reservoir were investigated, subsequently the species diversity indexes of phytoplankton were calculated to evaluate the eutrophication status of Nanwan reservoir from biologic aspect. The average phytoplankton biomass of Nanwan reservoir was 4.337 mg/L. The dominant algae of Nanwan reservoir was Cyanophyta which was a phylum of algae indicating water eutrophication. The Shannon-Weiner index of Nanwan reservoir was 3.45, the Pielou index was 1.15, and the Simpson’s index was 0.84, respectively. Evaluation based on the species composition, dominant species, biomass and species diversity index of phytoplankton indicated that the trophic state of Nanwan reservoir was between mesotrophication and eutrophication.
3.The effects of changing ratio between silver carp(Hypophthalmichthys molitrix) and bighead carp(Aristichthys nobilis) on water quality and plankton
Investigation was done to study the effect of changing the ratio of silver carp to bighead carp from 20∶80 to 40∶60(the biomass of silver carp was increased from 43.73g/m2 to 87.47g/m2, the biomass of bighead carp was decreased from 174.94g/m2 to 131.20g/m2). The results indicated that changing the silver carp to bighead carp ratio reduced the concentration of CODMn, BOD5 and chlorophyll a and increased the water body transparency significantly, thus improved water quality on a certain degree. Furthermore, although the regulation had little effect on the density and biomass of zooplankton, it reduced the density and biomass of phytoplankton significantly. Also, the regulation reduced the ratio of Cyanophyta in the algae colony and its biomass greatly and avoided the breakout of the water bloom of these alages. |
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