浅水湖聚藻区沉积物还原性硫组分变化及其对水体黑臭的诱发机制

The process of high density of algae gathering, death and decomposition would lead to the abnormal elevation of the reduced sulfur in surface sediments from eutrophic lake. Therefore, this would be the finality reserved factors and which would induce the bloom of the black and odour water pollution affair. Hence, it was very necessary to understand the composition of reduced sulfur and its change characteristic, which would be an important guidance to make clear the occurring risk and mechanism of the bloom of black and odour water pollution affair. This research selected the algae loaded area as the subject investigated and used measures including micro-interface analysis, microorganisms community analysis. Other measures such as in situ equilibrium dialysis samplers (peepers), laboratory dynamic simulation, chemical extraction and x-ray absorption near-edge structure spectroscopy (XANES), 34S isotope tracer were also used. Using these measures mentioned above, we could know the spatial and temporal variation of the reduced sulfur and therefore identified the species variant from the sediment loaded by algae. Information including the response characteristic of sediment reduced sulfur to algae loaded, changing of environmental conditions and microorganisms community, and the influence of algae loaded and bloom of the black and odour water on the transformation of sulfur speciation. With all of the key problems solved, we could deeply understand the variation law and the composition of reduced sulfur, and the induced mechanism to the bloom of black and odour water pollution affair from the sediments of the algae overload areas. This could provide a scientific support to the government of water pollution of the algae overload area from shallow lakes.

高密度蓝藻聚集、死亡分解会引起湖底表层沉积物硫等物质的还原形态异常升高，从而成为诱发黑臭等恶性水污染事件发生的决定性储备条件。因此，弄清沉积物还原性硫组分构成及其变化规律对于探究水体黑臭的发生风险和机制具有重要的指导作用。本研究以浅水湖聚藻区为研究对象，运用界面微环境及微生物群落结构分析，借助Peeper原位间隙水获取、室内动态模拟、化学提取及硫同步辐射（S-XANES）、34-S同位素示踪等手段，通过现场季节性采样和黑臭发生/未发生过程模拟，分析聚藻区沉积物还原性硫时空变异特征，确定还原性硫变异的种类；探讨沉积物还原性硫组分、界面微环境及微生物群落结构变化对水体黑臭发生的响应规律；阐明水体黑臭发生对沉积物硫形态转化的影响，揭示聚藻区沉积物还原性硫组分变化及其对水体黑臭发生的诱发机制，为浅水湖聚藻区藻源性水污染治理提供科学依据。

高密度蓝藻聚集、死亡分解会引起湖底表层沉积物硫等物质的还原形态异常升高，从而成为诱发黑臭等恶性水污染事件发生的决定性储备条件。因此，弄清沉积物还原性硫组分构成及其变化规律对于探究水体黑臭的发生风险和机制具有重要的指导作用。.本课题处置了3个研究内容：（1）聚藻区沉积物还原性硫时空变异特征研究；（2）聚藻区沉积物还原性硫变化对水体黑臭发生的响应规律研究；（3）沉积物硫形态转化与组分构成对聚藻区水体黑臭的诱发机制研究。. 本课题主要以太湖聚藻区为研究对象，通过蓝藻爆发前、爆发期以及爆发后的时间节点对聚藻区以及非聚藻区中理化性质以及间隙水以及沉积物中还原性铁硫的地球化学特征进行了详细的研究。结果发现聚藻区还原性铁硫的含量明显高于非聚藻区，其中作为水体黑臭事件中主要的还原性硫的诱发者酸挥发性硫（AVS）在聚藻区的沉积物的含量是非聚藻区的2至10倍，且聚藻区沉积物中氧化还原电位也显著低于非聚藻区，并确认了还原性硫变异的主要因素是藻源性有机碳的输入、以及氧化还原电位的波动等因素。借助硫形态提取与硫同步辐射技术(S-XANES),对沉积物内硫形态分布特征进行研究。结果表明,沉积物中硫分布具有明显的季节性波动特征,夏季沉积物中还原性硫含量要显著高于春季。硫形态提取结果显示,聚藻区沉积物中酸可挥发性硫、黄铁矿硫的平均浓度分别是非聚藻区的12.7、4.16倍,表明蓝藻聚集有利于还原性硫的产生。S-XANES分析结果也表明聚藻区沉积物内FeS、FeS2和ES的平均百分比含量明显高于非聚藻区。通过室内水体黑臭模拟实验表明，底泥是湖泛发生必须物质二价铁和还原性硫的最重要来源，藻体的存在主要是通过其耗氧营造湖泛必须的低氧缺氧环境。因此推断，富集铁、硫以及生物有机体的底泥将会更易诱发湖泛的发生。微生物添加实验表明，温度、二价铁和硫还原菌（SRB）可以促使湖泛中挥发性致臭硫化物的增加。上述研究揭示了湖泊聚藻区水体黑臭的发生机理，为防控水体黑臭的发生提供策略和技术支撑。