The sources, seasonal variation and transported fluxes of the riverine particulate organic carbon of the Zengjiang River, Southern China

The transfer of carbon from land to sea via rivers represents a major link in the global carbon cycle. The Zengjiang River drainage, a second-classed tributary of the Zhujiang (Pearl) River drainage, lies in the subtropical monsoon area, southern China, with the Tropic of Cancer through it. Suspended sediments had been collected for four weeks from the Zengjiang River and represent for a whole hydrological year. The main biogenic elements, including carbon, nitrogen and hydrogen were analyzed, and two major potential contributions from soil organic matter and aquatic algae were estimated. The research results indicated that the organic carbon in the suspended sediments originates mainly from primary production, and that from the soil organic carbon represented only 37.24% for the coarse sediments and even less 11.11% for the fine sediments. The transported particulate organic carbon flux in the Zengjiang River drainage amounts to 0.83×10~6?g·km~(-2)·a~(-1), in which that comes from soil erosion processes is 0.22×10~6?g·km~(-2)·a~(-1).