Vertical Differentiation Characteristics and Environmental Regulatory Mechanisms of Microbial Biomass Carbon and Nitrogen in Coastal Wetland Sediments from the Northern Yellow Sea

作者：Yue Zhang, Haiting Xu, Jian Zhou · 发表于：Sustainability · 年份：2025 · DOI：10.3390/su17178082 · 被引用次数：1 · 研究领域：Coastal wetland ecosystem dynamics

Coastal saltmarsh wetlands play a pivotal role in global carbon and nitrogen cycling, yet the vertical distribution characteristics of sediment carbon and nitrogen and their regulatory mechanisms remain uncertain. Microbial biomass carbon (MBC) and nitrogen (MBN) serve as critical indicators of ecosystem functioning, representing the most labile organic fractions that directly mediate biogeochemical processes in coastal wetlands. We investigated Yalu River Estuary coastal wetlands in the northern Yellow Sea. Sediment cores (0–100 cm depth) were collected and stratified into 20-cm intervals to analyse physicochemical properties and carbon–nitrogen indicators, enabling quantitative assessment of vertical distribution patterns and environmental drivers. The key findings are as follows: (1) Both microbial biomass carbon (MBC) and nitrogen (MBN) exhibited significant depth-dependent decreases, with MBC decreasing sharply by 45% (90.42 to 60.06 mg/kg) in the 40–60 cm layer and MBN decreasing by 50% (7.50 to 3.72 mg/kg) in the 80–100 cm layer. Total carbon (TC) peaked in the 40–60 cm layer (6.49 g/kg), whereas total nitrogen (TN) continuously decreased (from 0.51 (surface) to 0.24 g/kg (bottom)). (2) Depth-specific controls were identified: Surface layers (0–20 cm) were governed by tidal scouring (causing TC loss) and pH buffering; subsurface layers (20–40 cm) were constrained by moisture content (MC) and bulk density (BD), with partial mitigation by labile TC; and deeper layers (40...