Coal fly ash is a major carbon flux in the Chang Jiang (Yangtze River) basin
Gen Li, Woodward W. Fischer, Michael P. Lamb, A. Joshua West, Ting Zhang, Valier Galy, Xingchen Wang, Shilei Li, Hongrui Qiu, Gaojun Li, Liang Zhao, Jun Chen, Junfeng Ji
Abstract
Significance Coal combustion releases CO 2 but also leaves behind solid waste, or fly ash, which contains considerable amounts of carbon. The organic carbon sourced from fly ash resists chemical breakdown, and we find that it now contributes nearly half of the fossil organic carbon exported by the Chang Jiang—the largest river in Asia. The fly ash flux in this basin is similar to the natural sediment flux to the oceans because dam building has reduced sediment transport, while increased coal consumption generates abundant fly ash. Our results show that fly ash is an important component of the present-day carbon load in rivers and illustrates that human-driven carbon cycling can match the pace of the geological carbon cycle at decadal timescales.