Spatial Distribution of Dissolved Organic Carbon during the Wet Season in Northern Poyang Lake and Related Affecting Factors

Dissolved organic carbon (DOC) is the largest organic carbon component in water ecosystems and plays an important role in carbon cycle process. The concentrations of DOC and other water environmental factors were investigated during the wet season (August 2014) in northern Poyang Lake. In this paper, the primary objective was to illustrate the spatial distribution of DOC in northern Poyang Lake. Additionally, the relationships between DOC and water environmental factors such as chromophoric dissolved organic matter (CDOM), chlorophyll a (Chl a), total suspended matter (TSM), and turbidity were analyzed. The results showed that concentrations of DOC in northern Poyang Lake were relatively low during the wet season, with an averaged value of 1.927 mg/L ranged between 1.607 and 2.821 mg/L. Spatially, the concentrations of DOC were higher in the north and lower in the south with variation of water levels. Correlation analysis showed that DOC was positively correlated with CDOM, TSM and turbidity, but not related with Chl a. Combined with field investigation, the results indicated that DOC in northern Poyang Lake was more likely come from terrestrial sources, and it had a certain relationship with frequently sand-excavating in the northern water area connected with the Yangtze River.