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Alternative TitleEcologucal studies on TN:TP ratio, phytoplankton and microcystins in 33 shallow lakes in the middle and lower reaches of the Yangtze river
Thesis Advisor谢平
Degree Grantor中国科学院水生生物研究所
Place of Conferral水生生物研究所
Keyword长江 浅水湖泊 富营养化 微囊藻毒素
Abstract所研究湖泊被分为四类,通江湖泊、半通江湖泊、城市湖泊和城郊湖泊。其中,城市湖泊由于接纳城市工业废水和生活污水,富营养化最严重,其平均的总氮浓度为其它三种类型湖泊的4-6倍,总磷浓度为7-16倍;半通江湖泊和城郊湖泊富营养程度较轻,通江湖泊由于沿岸污染物的大量输入,使其面临严重的富营养化趋势。 对长江中下游地区33个浅水性湖泊的氨态氮(NH4+-N)、硝态氮(NO3--N)、亚硝氮(NO2--N)和 氮磷比(TN:TP)在生长季节和非生长季节的变化进行了研究。各营养盐浓度之间均呈显著正相关,整体上生长季节的相关性较好。 TN:TP比随TP浓度呈降低的趋势,生长季节总氮及各种无机氮的浓度明显低于非生长季节,说明氮(尤其是氨氮和硝态氮)在生长季节的降低是TN:TP比降低的重要原因。生长季节和非生长季节TN:TP比的变化幅度与营养状态密切相关,生长季节TN:TP比低于非生长季节的现象在富营养、超富营养状态十分明显。 蓝藻分布与环境因子关系的研究显示蓝藻生物量生长季节比非生长季节高很多,生长季节最大值出现在三角湖 (5.719 mg L-1), 最小值出现在天鹅洲 (0.001 mg L-1);半通江湖泊蓝藻生物量显著高于其它类型湖泊,在生长季节,半通江湖泊和城郊湖泊蓝藻生物量占浮游植物总生物量的40%, 而通江湖泊和城市湖泊仅占不到20%;主成分分析显示在生长季节微囊藻属(Microcysits)与碳营养关系密切,暗示着碳源可能是夏季微囊藻水华爆发的主要限制因子。 微囊藻毒素与环境因子关系的研究显示半通江湖泊的平均微囊藻毒素浓度是通江湖泊的33倍,城市湖泊和城郊湖泊的6倍。淀山湖的毒素浓度最高为8.574 μg/L。研究显示MC-RR和LR是长江中下游湖泊群中微囊藻毒素的主要类型,RR、YR和LR与Chla 蓝藻生物量,微囊藻生物量,鱼腥藻生物量呈显著相关,说明在这些湖泊中微囊藻毒素主要由微囊藻和鱼腥藻产生。非直线间隔最大回归显示透明度、氮磷比、氨氮与微囊藻毒素呈否定指数相关,总氮、总磷、TN、TP、NO3- + NO2-与微囊藻毒素呈单峰曲线关系;主成分分类分析显示微囊藻毒素浓度主要和生物因子中微囊藻的生物量,理化因子中温度关系密切。
Other AbstractThe lakes in this study were divided into four types: river connected lakes (RL), seasonal river connected lakes (SL), city lakes (NC) and non-urban lakes (NE). Among the four lake types, city lakes were the most serious, with TN concentration 4-6 times and TP concentration 7-16 times that of the other three lake types. The seasonal river connected lakes and non-urban lakes were less eutrophic than city lakes, and the river connected lakes were faced with seriously eutrophication because of contamination input from the littoral zone. The changes of NH4+-N, NO3--N, NO2--N and TN:TP ratio were studied during growth and non-growth seasons in the 33 lakes. There were significant positive correlations among all nutrient concentrations, and the correlations were stronger in growth season than in non-growth season. In addition, TN:TP decreased with TP concentration decline, and TN and inorganic nitrogen concentrations were obviously lower in growth season than in non-growth season, suggesting that the decrease of nitrogen (especially NH4+-N and NO3--N) was an important reason for the decrease of TN:TP in growth season. The biomass of cyanobacteria was very higher in growth season than in non-growth season, and the highest value in growth season was 5.719 mg L-1 in Sanjiao lake, the lowest value was 0.001 mg L-1 in Tian’e Zhou. Cyanobacteria in the seasonal lakes were much higher than those in other type lakes. In growth season, cyanobacteria in non-urban lakes and seasonal lakes were more than 40% in total phytoplankton biomass among the four type lakes, cyanobacteria in river connected lakes and city lakes were less than 20% in total phytoplankton biomass. A survey of 30 lakes was conducted to reveal how environmental and biological variables were associated with the concentration of the cyanotoxin, microcystin (MC). The results showed that mean MC concentration in seasonally river-connected lakes (SL) was nearly 33 times that in permanently river-connected lakes (RL), and more than six times that in city lakes (NC) and non-urban lakes (NE) which were not connected to the Yangtze River. The highest MC (8.574 μg L) was detected in Dianshan Lake. MC-RR and MC-LR were the primary toxin variants in our data. MC-RR, MC-YR and MC-LR were significantly correlated with Chl a, biomass of cyanobacteria, Microcystis and Anabaena, indicating that microcystins were mainly produced by Microcystis and Anabaena sp. in these lakes. Nonlinear interval maxima regression indicated that the relationships of Secchi depth, total nitrogen (TN), total phosphorus (TP) and NH4+ with MC were characterized by negative exponential curves. The relationships between MC and TN, TP, NO3-+ NO2- were fitted well with a unimodal curve. Multivariate analyses by principal component and classifying analysis indicated that MC was mainly affected by Microcystis among the biological factors and closely related with temperature among physicochemical factors.
Document Type学位论文
Recommended Citation
GB/T 7714
吴世凯. 长江中下游33个浅水湖泊氮磷比、浮游植物和微囊藻毒素的生态学研究[D]. 水生生物研究所. 中国科学院水生生物研究所,2007.
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