Hubei Key Laboratory of Regional Development and Environmental Response, Faculty of Resources and Environmental Sciences, Hubei University, Wuhan 430062, China.
Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, College of Resources and Environmental Engineering, Hubei University of Technology, Wuhan 430068, China.
Sci Total Environ. 2024 Jan 1;906:167752. doi: 10.1016/j.scitotenv.2023.167752. Epub 2023 Oct 12.
Heavy metal (HM) pollution is a major concern in freshwater ecosystem management. The different types of endogenous organic matter and the way their decomposition affects HM transformation in freshwater lakes is not well understood. An ex situ mesocosm study was conducted to compare HM transformation in sediments during anaerobic decomposition of cyanobacterial bloom biomass (CBB) and submerged cyanobacterial vegetation in Lake Taihu, known as Potamogeton malaianus (PM). Microbial community structures were examined through Illumina sequencing of 16S rDNA. Results indicate that Zn had a remarkably higher amount of potential mobile fraction than other heavy metals (Cr, Pb, Cu, Ni, and Cd) detected in sediments, especially in sediments collected from CBB-dominated areas (approximately 150 mg kg). CBB decomposition has caused a significant increase in exchangeable Zn content in sediments and a decrease in reducible Zn that was three times greater than PM decomposition. Additionally, oxidizable Zn content declined during CBB decomposition but increased during PM decomposition. Furthermore, the relative abundance of the main fermentative bacteria and some sulfate-reducing bacteria genera (e.g., Desulfomicrobium) were significantly associated with the HM content of exchangeable and reducible fractions during CBB decomposition. Overall, the findings indicate that Zn is more susceptible to endogenous organic matter decomposition than other metals in freshwater lakes, and the impacts of CBB decomposition on the transformation of heavy metals in sediment are greater than that of submerged macrophyte decomposition.
重金属（HM）污染是淡水生态系统管理中的一个主要关注点。不同类型的内源性有机物及其分解方式如何影响淡水湖中 HM 的转化尚未得到很好的理解。本研究采用现场中观模拟实验，比较了蓝藻水华生物量（CBB）和菹草（Potamogeton malaianus，PM）在太湖底泥厌氧分解过程中 HM 在沉积物中的转化。通过 Illumina 测序对 16S rDNA 进行分析，研究了微生物群落结构。结果表明，与其他重金属（Cr、Pb、Cu、Ni 和 Cd）相比，Zn 具有更高比例的潜在可移动形态，尤其是在 CBB 占主导地位的区域（约 150mg/kg）。CBB 分解导致沉积物中可交换 Zn 含量显著增加，而可还原 Zn 含量下降，降幅是 PM 分解的三倍。此外，在 CBB 分解过程中，氧化态 Zn 含量下降，而在 PM 分解过程中则增加。此外，一些发酵细菌和硫酸盐还原菌属（如脱硫微菌属）的相对丰度与可交换态和可还原态 HM 含量显著相关。总体而言，研究结果表明，在淡水湖中，Zn 比其他金属更容易受到内源性有机物分解的影响，CBB 分解对沉积物中重金属转化的影响大于沉水植物 PM 分解的影响。
