Increased Lateral Transfer of Soil Organic Carbon Induced by Climate and Vegetation Changes Over the Southeast Coastal Region of China

Abstract

Soil erosion and the subsequent lateral movement of soil carbon profoundly affect the spatial pattern of carbon sources and sinks in terrestrial ecosystems. The eight river basins of Fujian Province considered in this study are an important part of the southeastern coastal river basin of the ninth largest river system in China. In recent years, the erosion of soil and soil organic carbon in the southeast coastal region of China is not ideal owing to the high and concentrated rainfall, natural vegetation destruction, and other reasons. In this study, the soil organic carbon erosion and deposition rates related to erosion in the eight river basins of Fujian Province are quantified, and their spatial distribution characteristics are extracted. Based on the soil erosion rate from two national soil erosion surveys and topsoil carbon content from the Harmonized World Soil Database, we estimated that the lateral soil organic carbon erosion increased from 7.53 to 26.75 g C m−2 yr−1 in eight river basins of Fujian Province from 1995–1996 to 2010–2012. The soil organic carbon erosion rate in the eight river basins increased by 2.6 times, while the soil organic carbon erosion rate for the whole of China decreased by 44% during the same period. The increase in torrential rain and decrease in vegetation cover in the southeastern coastal areas largely contributed to the erosion of soil and soil organic carbon. The lateral transfer rate of soil organic carbon may be further exacerbated by the increase of torrential rain in the southeastern coastal areas of China.

Hypolimnetic deoxygenation enhanced production and export of recalcitrant dissolved organic matter in a large stratified reservoir

“…During the wet summer season, DOC concentrations in the upper river were low (~110 µmol/L) compared with Arctic (1028 ± 21 µmol/L; Cory et al, 2015), USA rivers with extensive wetlands (390 ± 172 µmol/L; Spencer et al, 2013;Bhattacharya and Osburn, 2020), and other Chinese rivers (e.g., Changjiang, 144 ± 24 µmol/L; Jiulong River, 161 ± 21 µmol/L; Guo et al, 2014). We ascribe these lower DOC concentrations to limited DOC flushing and dilution effects from the organic-poor soils of the SK watershed (Liu et al, 2019). DOC and bio-labile FDOM P increased from the upper river to the epilimnion of the reservoir (Fig.…”