Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, PR China.
Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
Sci Total Environ. 2019 Feb 20;652:696-708. doi: 10.1016/j.scitotenv.2018.10.260. Epub 2018 Oct 22.
Lake eutrophication and the resulting cyanobacterial blooms have become a global water environment problem. These eutrophic lakes usually have relatively high internal phosphorus loading such as Fe-P to support the formation of cyanobacterial blooms. In order to reveal the mechanisms and processes of phosphorus cycling in lake sediments, in this study, Lake Chaohu was selected as the research area, and the effects of cyanobacterial bloom decomposition on the horizontal distribution pattern of Fe-P was studied by field investigation and laboratory simulations. According to the phosphorus fractions in the sediments, Lake Chaohu can be divided into three lake areas, and the Fe-P content in western Chaohu is the highest (908.6 ± 54.9 mg kg). The contents and proportions of Fe-P were significantly positively correlated with cyanobacterial pigments in sediments, but they negatively correlated with undegraded chl-a, especially when the Fe-P content was <400 mg kg. Based on these statistical analyses, we proposed a hypothesis that the settled cyanobacterial organic matters (COM) could promote the formation of Fe-P. This hypothesis was proved by the simulation experiments of adding COM to the oligotrophic lakeshore clay. The results suggested that the content and proportion of Fe-P in sediments were significantly increased by the COM addition, and also, they were significantly positively correlated with the decomposition of the COM. The formation processes of Fe-P were further confirmed by the analysis of Fourier transform infrared (FT-IR) spectra. Microbial community analysis suggested that the bacterial species including FeOB and genus Pseudomonas might play an important role in the formation of Fe-P. This study suggested that the settled COM could enhance the eutrophication of sediments through a positive feedback cycle. Therefore, it is necessary to carry out bloom removal and sediment dredging simultaneously, and only then the cyanobacterial bloom can be effectively controlled.
湖泊富营养化和由此产生的蓝藻水华已成为全球性的水环境问题。这些富营养化湖泊通常具有相对较高的内部磷负荷，例如 Fe-P，以支持蓝藻水华的形成。为了揭示湖泊沉积物中磷循环的机制和过程，本研究选择巢湖作为研究区域，通过野外调查和实验室模拟研究了蓝藻水华分解对 Fe-P 水平分布格局的影响。根据沉积物中的磷形态，巢湖可分为三个湖区，其中西部巢湖的 Fe-P 含量最高（908.6±54.9mg/kg）。Fe-P 的含量和比例与沉积物中的蓝藻色素呈显著正相关，但与未降解的chl-a呈显著负相关，尤其是当 Fe-P 含量<400mg/kg 时。基于这些统计分析，我们提出了一个假设，即沉降的蓝藻有机物质（COM）可以促进 Fe-P 的形成。通过向贫营养湖滨粘土中添加 COM 的模拟实验验证了这一假设。结果表明，COM 的添加显著增加了沉积物中 Fe-P 的含量和比例，并且与 COM 的分解呈显著正相关。通过傅里叶变换红外（FT-IR）光谱分析进一步证实了 Fe-P 的形成过程。微生物群落分析表明，包括 FeOB 和假单胞菌属在内的细菌种类可能在 Fe-P 的形成中发挥重要作用。本研究表明，沉降的 COM 可以通过正反馈循环增强沉积物的富营养化。因此，有必要同时进行水华去除和底泥疏浚，只有这样才能有效地控制蓝藻水华。
