Abstract:

Suspended solids were sampled at 9 sites on the Wuyuer River and its main tributaries in 20082009. Contents, stable carbon isotopes (13C) and cosmogenic carbon isotope (14C) compositions of particulate organic carbon (POC) in suspended solids were used to constrain the relationship between the sources of particulate organic carbon and soil erosion in drainage basin. Particulate organic carbon is mainly of organic matter of deep soil. Also, the organic matter in deep soil is dominated by grassland vegetation residue, and lack of corn root residue. Particulate organic carbon of suspended solids in Zhalong wetlands is mainly determined by modern carbon formed in it, with little or absence of terrestrial influence. 14C apparent ages of  POC  of Wuyuer River and its main tributaries in high water periods are older than those in low water periods. The migration distance of particulate matter in rainfall season is shorter than that in rainless season. Compared to the other rivers, the characteristic and variability of 14C apparent ages of particulate organic carbon suggested that soil erosion in Wuyuer River is very severe, and show obvious seasonal difference. Considering the difference of origin and migration distance of particulate organic carbon, we calculated the contribution of main tributaries to Wuyuer River in high water periods from the mixing model.

Key words: particulate organic carbon (POC), carbon isotope, soil erosion; , Wuyuer River, drainage basin