太湖贡湖湾2-甲基异莰醇（2-MIB）时空变化特征及影响因子

湖泊水体丝状蓝藻的大量出现会产生嗅味代谢物,引发由2-甲基异莰醇(2-MIB)主导的嗅味问题,威胁饮用水安全。太湖贡湖湾是苏州市、无锡市的重要饮用水源地,近年由2-MIB引起的水体嗅味问题时有出现,但相关研究鲜有报道。为掌握贡湖湾2-MIB时空变化特征及影响因子,研究分别于2022年3—12月和高温期间(7月29日—8月29日)开展逐月及高频调查。逐月调查结果显示,贡湖湾2-MIB浓度变化季节性差异显著,夏季浓度最高,可达124.3 ng/L。贡湖湾各点2-MIB的空间分布无明显差异。高频调查结果发现,高温期间贡湖湾入湖口附近水域2-MIB浓度变化剧烈,最高值可达1385 ng/L,超其嗅阈值(10 ng/L)近140倍。本文研究借助人工镜检及功能基因高通量测序技术,首次揭示拟浮丝藻是高温时段贡湖湾2-MIB的主要来源。主成分分析及相关性分析结果表明,水温、月均太阳辐射、总磷和叶绿素a是影响贡湖湾2-MIB逐月变化的关键环境因子。高温时段贡湖湾拟浮丝藻的时空变化主要受水温、日均太阳辐射、风力、硝态氮和溶解性总磷及微囊藻多个环境因子共同影响。

Spatial and temporal variation characteristics of 2-methylisoborneol and associations with environmental factors in Gonghu Bay, Lake Taihu

The massive occurrence of filamentous cyanobacteria in lake water bodies can produce odor metabolites, triggering odor problem dominated by 2-MIB and threatening drinking water safety. Gonghu Bay of Lake Taihu is an important drinking water source for Suzhou City and Wuxi City. In recent years, water odor problems caused by 2-MIB have occurred over time, but related research has rarely been reported. To grasp the spatial and temporal characteristics of 2-MIB and its influencing factors in Gonghu Bay, monthly and high-frequency surveys were conducted from March to December and during the high temperature period (July 29 to August 29) in 2022, respectively. The results of the monthly survey showed that the seasonal variation of 2-MIB concentration in Gonghu Bay was significant, with the highest concentration of 2-MIB reaching 124.3 ng/L in summer. There was no significant difference in the spatial distribution of 2-MIB in Gonghu Bay. The results of the high-frequency survey showed that the concentration of 2-MIB in the waters near the inlet of Gonghu Bay varied dramatically during the high temperature period, with the highest value reaching 1385 ng/L, which exceeded its olfactory threshold (10 ng/L) by nearly 140 times. Based on artificial microscopy and high-throughput sequencing of functional genes, the study revealed for the first time that Planktonthricoides was the main source of 2-MIB in Gonghu Bay during high temperature periods. The results of principal component analysis and correlation analysis showed that water temperature, monthly mean solar radiation, total phosphorus and chlorophyll-a were the key environmental factors influencing the seasonal variation of 2-MIB concentration in Gonghu Bay. The spatial and temporal variation of Planktonthricoides in Gonghu Bay during the high temperature period was mainly influenced by several environmental factors, including water temperature, daily average solar radiation, wind force, nitrate nitrogen, dissolved total phosphorus and Microcystis.