Analysis of sedimentary organic carbon origin in Taihu lake using by carbon and nitrogen stable isotope ratio

Contribution of autochthonous (cyanobacteria) and allochthonous (reed) organic matter to sediment and utilization of organic matter by bacteria and benthic animals in northeast area of hypereutrophic lake, Taihu lake were investigated. Although Taihu lake suffered algal bloom almost over a year, two sources mixing model of carbon stable isotope ratio analysis showed that contribution of reed was more dominant than cyanobacteria in Taihu lake. Food web analysis using by bulk carbon and nitrogen stable isotope ratio indicated benthic animals mainly assimilated cyanobacteria. Moreover carbon stable isotope ratio of bacterial fatty acids in sediment showed bacteria have also assimilated cyanobacteria. These findings indicated turnover of cyanobacterial carbon was faster than reed, which seemed to be a reason sediment organic carbon was mainly originated from reed in Taihu lake.