HE Jing, FANG Yin, LIN Minglan, LIN Tian

(1. College of Marine Ecology and Environment, Shanghai Ocean University, 

Shanghai, 201306, China)

Abstract：In recent years, with the deepening of the understanding of the carbon cycle process, the horizontal migration of terrestrial organic carbon plays an important role in river and ocean ecosystems, therefore, it is of great significance to clarify its transport fluxes. In this study, from January to December in 2018, surface water samples with monthly time resolution were collected at Datong Station in the lower reaches of the Yangtze River. The organic carbon and black carbon concentrations in the water suspended particulate matters were analyzed to understand their seasonal variations, and to estimate the corresponding fluxes. The results showed that the total suspended solids (TSS) concentrations ranged from 11.77 mg/L to 141.54 mg/L, with the average was 44.07 mg/L ± 32.80 mg/L; the particulate organic carbon (POC) concentrations ranged from 0.37 mg/L to 1.52 mg/L, with the average was 0.57 mg/L ± 0.33 mg/L; the particulate black carbon (PBC) concentrations ranged from 0.04 mg/L to 0.46 mg/L, with the average was 0.10 mg/L ± 0.11 mg/L. The TSS, POC and PBC presented relatively consistent seasonal variations: the highest concentrations were observed in summer, while the lowest in winter, the spring and autumn were similar. Both PBC and POC were significantly positive correlated with TSS, which suggested that rainfall erosion and discharge carrying were the dominant sources that affected the variations of PBC and POC concentrations at Datong Station. In this study, the fluxes of PBC and POC at Datong Station of the Yangtze River were 2.05×1011 g/yr and 1.05×1012 g/yr, respectively. The PBC fluxes accounted for 19.54% of the POC fluxes. Moreover, the transported fluxes of POC and PBC were concentrated in the rainy season, accounting for 88.24% and 79.57% of the annual fluxes, respectively.

Key words：the Yangtze River; organic carbon; black carbon; fluxes

EARTH AND ENVIRONMENT Vol.51, No.1, Tot No.351, 2023, Page 1