Spatial and temporal variation in DOC in the Yichun River, China

Spatial and temporal variations in the concentration and flux of the dissolved organic carbon (DOC) in the Yichun River, China were investigated. It was found that in the summer, DOC in the river water originated primarily from allochthonous sources. There was a synchronous fluctuation in the DOC contents and flow rate. During the winter season when the river was totally covered in ice, the autochthonous source became dominant and the DOC content was inversely proportional to the flow rate simply due to the dilution effect. Two equations were derived to estimate DOC levels based on flow rate in the summer and winter, respectively. Spatially, the DOC increased downstream throughout the year. The annual DOC flux from the Yichun River drainage basin was calculated to be 7113 ton/a, or 2.88 gC/m2•a, among which over 87% occurred during 4 months of the wet season from June to September.