太湖水体及表层沉积物磷空间分布特征及差异性分析

Space Distribution Characteristics and Diversity Analysis of Phosphorus from Overlying Water and Surface Sediments in Taihu Lake

通过对水体不同程度富营养化湖泊——太湖全湖40个位点的高密度采样分析,得到太湖水体及表层沉积物各污染因子在太湖的空间分布特征图,结果表明,太湖水体中SRP、TP、TN及沉积物中TOC、TN、TP及P的各形态等在空间上表现出明显的分异性,水体中污染物主要分布于竺山湾、五里湖、梅梁湾及太湖西部等湖区,TN、TP最低值为0.05、0.88mg·L-1.沉积物中Fe-P的分布与水体中TP类似,含量在29.13～258.31mg·kg-1之间变化.Ca-P除主要分布于南部太湖及东太湖外,西北部湖区也见大量蓄积,最高值达357.68mg·kg-1.OP的高值分布于西北部湖区,最高值达371.91mg·kg-1.沉积物中IP占TP的含量高于OP,最高值高出OP含量约50%.IP中Fe-P的比例虽然低于Ca-P,但与水体中SRP、TP之间的高度相关性(R为0.49、0.64),指示Fe-P的内源释放为太湖水体中磷的重要来源之一.而沉积物中TOC与C/N、TN、TP及P的各形态之间的显著相关性,表明了高有机质含量更利于对营养盐的蓄积埋藏.太湖水体及表层沉积物各指标空间上表现出如此明显的区域性差异,除受不同湖区入湖污染源直接作用外,还和各参数不同的生物地球化学行为有关.

The physi-chemical indexes in the overlying water and surface sediments of Taihu Lake,an eutrophic shallow lake,were determined. Then,the isopleth maps of spatial distribution of each parameter were illustrated. The results show that the concentrations of SRP,TP and TN in the overlying water and TOC,TN and TP as well as phosphorus fractions in surface sediments exhibit distinct diversity in spatially. The lowest values of TP and TN were 0. 05,0. 88 mg·L -1 ,respectively. The concentrations of Fe-P ranged from 29. 13 to 258. 31 mg·kg^-1. Besides,the northwest lake regions,high-load Ca-P was surveyed in the South Taihu Lake and East Taihu Lake with the highest value of 357. 68 mg·kg^-1. The highest concentration of OP,371. 91 mg·kg^-1 ,was detected in the northwest region of the lake. IP takes up a greater proportion of TP than OP,and the highest value is approximately 50% higher than the lowest value. Fe-P has higher percentage in IP compared with Ca-P. Significant correlation between Fe-P,SRP and TP showed that Fe-P was the important phosphorus source of the overlying water（R：0. 49,0. 64）. Furthermore,high Correlation coefficients between TOC,TOC,C /N,TN,TP and phosphorus fractions suggest that higher concentration of organics was favor to the accumulation and burial of nutrients. The high-load contaminants exist principally in the Zhushan Bay,Wulihu Lake,Meiliang Bay and the northwest region of Taihu Lake. Significant heterogeneity of nutrients distribution in space of Taihu Lake connects with direct action of emission load of sewage. Simultaneously,different biogeochemical behaviors of each parameter play an important role.