Deposition- and transport-dominated erosion regime effects on the loss of dissolved and sediment-bound organic carbon: Evaluation in a cultivated soil with laboratory rainfall simulations

Authors: WANG, LINHUA - South China Botanical Garden; YEN, HAW - Texas A&M University; WANG, XIANG - China Agricultural University; Huang, Chi Hua; SUN, JIAMEI - South China Botanical Garden; Hammac Ii, Warren; WANG, YAFENG - Chinese Academy Of Sciences

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/14/2020
Publication Date: 8/15/2020
Citation: Wang, L., Yen, H., Wang, X., Huang, C., Sun, J., Hammac II, W.A., Wang, Y. 2020. Deposition- and transport-dominated erosion regime effects on the loss of dissolved and sediment-bound organic carbon: Evaluation in a cultivated soil with laboratory rainfall simulations. Science of the Total Environment. 750. Article 141717. https://doi.org/10.1016/j.scitotenv.2020.141717.
DOI: https://doi.org/10.1016/j.scitotenv.2020.141717

Interpretive Summary: Soil erosion is a key process in the carbon cycle, because the top soil is high in carbon and vulnerable to erosion loss. Surface cover alters soil erosion process, therefore affecting sediment deposition and loss of soil organic carbon (SOC). Information on SOC loss induced by soil erosion and sediment deposition is limited. In a laboratory rainfall simulation study, the arrangement of surface cover on a 9.7 long slope was altered to create deposition-dominanted and transport-dominated conditions. When the cover is placed on the upper part of the slope, the process is transport dominated. The erosion process is deposition-dominated when the cover is placed at the lower portion of the slope. The surface coverage located downslope )or deposition-dominated condition) is shown to be more efficient in reducing runoff (21.9-85.7%) and sediment (67.6-98.3%) as compared to the condition when the upslope area was covered (or transport dominated). The transport of DOC and SBOC followed the same trend. This study provides new information on how surface condition affects erosion processes and the transport carbon that can be used to quantify carbon dynamics on the landscape.

Technical Abstract: Erosion-induced soil carbon loss has been identified as a critical process in the global carbon cycle. Surface coverage substantially alters the soil erosion process and the effects of net loss or deposition on soil organic carbon (SOC). However, information on SOC loss induced by soil erosion at the process level is limited. The aim of this study was to investigate how runoff and erosion regimes affect dissolved and sediment-bound organic carbon (DOC and SBOC) loss. Six simulated rainfall events were conducted on two laboratory plots (9.75 m × 1.83 m) with different surface coverages (17-83 %) and coverage distributions (upslope vs. downslope) using polypropylene geotextiles. The results showed that the variability in the process of runoff and sediment yield existed as a result of altered surface coverage over the erosion zone and covered zone on the slope. The erosion regimes can be identified as deposition- and transport-dominated processes, which were the main soil erosion subprocesses. The surface coverage located downslope is shown to be more efficient in reducing runoff (21.9-85.7%) and sediment (67.6-98.3%) as compared to the condition when the upslope area was covered. The transport of DOC (8.0-11.3 mg L-1) and SBOC (0.3-0.5 mg g-1) under deposition-dominated condition were greater than those under transport-dominated condition. This study provides important information that can be used to facilitate further implementations such as watershed modeling of soil carbon dynamics and the corresponding decision-making processes.