Quantities and Fluxes of Dissolved and Particulate Black Carbon in the Changjiang and Huanghe Rivers, China

Recent studies have suggested that large rivers play important roles in mobilizing and transporting black carbon (BC) from land to the ocean. However, the influence of the Changjiang and Huanghe, the two largest rivers in China, on the fate of BC has not been determined. In this paper, we present measurements of BC in both the dissolved and particulate phases in the Changjiang and Huanghe Rivers and in the coastal waters of the East China Sea (ECS). Our results show that dissolved black carbon (DBC) accounted for 3.0 +/- 0.4 % and 4.8 +/- 3.6 % of the total DOC pool in the Changjiang and Huanghe Rivers and 3.4 +/- 0.6 % of the DOC pool in the coast of the ECS. In addition, particulate black carbon (PBC) accounted for 13 +/- 0.9 % and 22 +/- 11 % of the POC pool in the Changjiang and Huanghe Rivers, respectively. We calculate that the Changjiang and Huanghe transported 4.7 x 10(10) gC and 1.7 x 10(9) gC of DBC, and 2.0 x 10(11) gC and 1.2 x 10(10) gC of PBC to the ECS and Bohai Sea in 2015. The large amounts of BC transported by the two rivers represent a major sink of anthropogenically derived organic carbon and could have a significant impact on the ecosystem and carbon cycling in China's marginal seas.