Abstract: Lake sediment can be a source as well as a sink of water pollutants and, hence, represents an important factor in lake ecology. Thus, more and more attention has been paid on the water quality of Beijing park lakes and the chemical characteristics of the sediments. This study detected variations in δ¹³C_org, C/N ratios, TOC and TN contents in the sediments from 19 Beijing park lakes collected in 2012 and 2013. The analyses focused on the sources of organic matter, the productivity and the eutrophic status of the lakes. The results showed that the δ¹³C_org and C/N values, and TOC and TON concentrations were significantly different among superficial sediments from different lakes, and the productivity and the eutrophic status of the lakes were also different. The sediments of three lakes showed minor contamination, whereas the other lakes were characterized by higher degrees of organic pollution. According to the δ¹³C_org values (-27.6‰ to -22.1‰) and C/N ratios (8.2-58.1), the sedimentary organic matter was mainly derived from sewage. Hence, the pollution of the lakes could be lowered by controlling the discharge of wastewater.

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