Check dam promotes soil organic carbon accumulation and nitrogen and phosphorus deposition

Mangroves are vital coastal ecosystems that provide essential ecological services, including carbon (C) sequestration and the removal of nitrogen (N) and phosphorus (P) pollution. With the expansion of agricultural activities and aquaculture, an increasing number of check dams have been constructed around mangrove wetlands, resulting in changes to the soil and sediment characteristics. However, the impact of these check dams on the content of C, N, and P, as well as their depth-dependence, remains largely unexplored.

To fill this knowledge gap, This research selected a natural mangrove wetland (NanSha wetland Park) and a neighboring check dam-affected mangrove wetland (Tantou wetland) in the Pearl River Estuary. To establish a causal relationship between check dams and variations in C and nutrient content, This research measured soil deposition depth using ²¹⁰Pb dating along the soil profile following check dam construction. This research then analyzed the content of C, N, and P in different soil components (bulk soil, microbial biomass, and extracellular enzymes) both before and after the dam construction.

This results revealed that the check dam significantly increased the contents of C, N, and P within the soil-microorganism-enzyme system. Additionally, check dams also enhanced the depth-dependence of soil C, with C varying more slowly than N and P in the natural mangrove but faster in the check dam-affected mangrove. These findings demonstrate that check dams can significantly promote C accumulation in mangrove ecosystems. Overall, This research highlights the implications of costal management for C accumulation and nutrient pollution removal in mangrove wetlands. The article link is: https://doi.org/10.1016/j.jenvman.2024.123341

Fig. 1. A conceptual framework illustrating the effects of check dams on C, N, and P content and their depth-dependence in different soil components.(Image by WANG et al)

Fig. 2. C, N, and P content in soil (a-c), microorganism (d-f), and enzyme (g-i) along the soil profile in the mangroves of the Wetland Park and the Tantou wetland.(Image by WANG et al)