Hou Lei, Liu Pengming, Liang Qibin, Chen Ting, Liu Xue, Yu Junbao, Gao Lei
Yunnan Key Laboratory of Plateau Wetland Conservation, Restoration and Ecological Services, College of Ecology and Environment, Southwest Forestry University, Kunming 650224, China.
College of Soil and Water Conservation, Southwest Forestry University, Kunming 650224, China.
J Hazard Mater. 2025 Aug 15;494:138649. doi: 10.1016/j.jhazmat.2025.138649. Epub 2025 May 16.
The microbial-driven remobilization of trace metals in wetland sediment determines their release risks in water bodies. This study combined in situ passive sampling, 16S rDNA high-throughput sequencing, metal speciation calculation, and structural equation modeling to investigate the mechanisms driving the microbially mediated remobilization of sediment nickel (Ni) and cobalt (Co) under their potential competitive interplay in a free water surface wetland in southwest China. Inverse vertical profiles of labile Ni and Co were observed during the wet season. In sediment porewaters, Ni-inorganic and Ni-organic complexes were the dominant species (>52.4 %) whereas Co was present mainly as free ions (>58.4 %), due to the greater complexing affinity of Ni with inorganic and organic ligands. Two genera of mineralizing bacteria, Dechloromonas and Geobacter, indirectly enhanced the bioavailability of Ni and decreased that of Co, by responding to the ion abundance and redox conditions in sediment, particularly during the wet season. Wetland sediment acted as a constant source of Co release into the water column (0.02-0.33 μg m d), whereas it served as a source of Ni (0.18-0.48 μg m d) during the dry season and shifted to a sink (-0.98 to -0.33 μg m d) during the wet season. The oversaturation of vivianite near the interface was mainly responsible for the inhibited diffusive release of sediment Ni during the wet season.
湿地沉积物中微生物驱动的痕量金属再活化决定了它们在水体中的释放风险。本研究结合原位被动采样、16S rDNA高通量测序、金属形态计算和结构方程模型，在中国西南部一个自由水面湿地中，研究在镍（Ni）和钴（Co）潜在竞争相互作用下，驱动沉积物中微生物介导的Ni和Co再活化的机制。在雨季观察到活性Ni和Co的反向垂直剖面。在沉积物孔隙水中，由于Ni与无机和有机配体具有更强的络合亲和力，Ni-无机和Ni-有机络合物是主要形态（>52.4%），而Co主要以游离离子形式存在（>58.4%）。两类矿化细菌，脱氯单胞菌属和地杆菌属，通过响应沉积物中的离子丰度和氧化还原条件，间接提高了Ni的生物有效性并降低了Co的生物有效性，特别是在雨季。湿地沉积物是Co释放到水柱中的恒定来源（0.02 - 0.33 μg m d），而在旱季它是Ni的来源（0.18 - 0.48 μg m d），在雨季则转变为汇（-0.98至-0.33 μg m d）。雨季期间，界面附近蓝铁矿的过饱和是沉积物中Ni扩散释放受抑制的主要原因。
