Coral Record of Increased Soil Erosion Since East and Southeast Asia Economic Boom

Abstract

Soil erosion in East and Southeast Asia is believed to have increased significantly since the regional economic boom of the 1970s-1980s. However, limited records of soil erosion make it difficult to understand and indeed verify such changes. Here we present two new monthly resolved Ba/Ca records from Porites coral skeletons from southern Taiwan and central Vietnam, supplemented with some sporadic monthly and annually resolved coral delta Ba-138/134 data. Our records span the 1980s to the 2000s and suggest that there were intervals of elevated seawater Ba concentrations (Ba-sw) during the intervals 1987-1995 in southern Taiwan and 1992-2001 in central Vietnam. In combination with evidence for insignificant changes in regional seawater delta Ba-138/134 values, model simulations, and other published coral Ba/Ca records from Lanyu (offshore southeast Taiwan) and Hainan, we infer that the intervals of high Ba-sw values are linked to soil erosion associated with land use changes and socioeconomic developments. The increased sediment loads are also likely responsible for the recent degradation of regional coral reefs. Our study provides new insights into regional soil erosion histories, which may prove useful for guiding soil conservation and sustainable land management.