State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China; Flathead Lake Biological Station, University of Montana, Polson, MT, 59860, USA.
Flathead Lake Biological Station, University of Montana, Polson, MT, 59860, USA.
Environ Pollut. 2022 Aug 1;306:119445. doi: 10.1016/j.envpol.2022.119445. Epub 2022 May 9.
Microplastics are contaminants that are closely associated with human activity and are often abundant even in remote areas. As the largest natural freshwater lake in the western USA, Flathead Lake is a suitable site to study microplastics in lakes in less-populated areas of North America. Our assessment of microplastics in lake surface water samples showed that microplastic densities and concentrations in Flathead Lake were similar to those in other lakes located in less-populated areas around the world, with densities ranging from 8.00 × 10 to 4.22 × 10 particles/km with a mean concentration of 1.89 × 10 particles/km. Dry deposition rates for microplastics ranged from 4 to 140 particles/m/day with an average of 69 particles/m/day and were significantly higher in the fall. Microplastic concentrations in wet deposition ranged from 0.006 particles/mL to 0.050 particles/mL with highest concentrations in winter and lowest in summer. Fibrous microplastics were predominant in both lake water and atmospheric deposition. The high densities of microplastics in the sample sites located near the Flathead River inlet suggests that the river is an important source of microplastics to Flathead Lake. The high densities of microplastics and high proportions of non-fibrous microplastics near populated areas of the lake imply that local human activities also affect microplastics in Flathead Lake. Although the annual flux of microplastics in dry deposition was higher than that in wet deposition, the relatively modest difference suggests that precipitation might enhance the deposition of microplastics. The results of this study indicate that instituting increased control measures that target both reducing the microfibers generated by laundry and improving the overall level of plastic waste management in the watershed may help in controlling microplastic levels in Flathead Lake.
微塑料是与人类活动密切相关的污染物，即使在偏远地区也很常见。作为美国西部最大的天然淡水湖，弗拉特黑德湖是研究北美人烟稀少地区湖泊中微塑料的理想地点。我们对湖泊地表水样本中微塑料的评估表明，弗拉特黑德湖中微塑料的密度和浓度与世界其他人口较少地区的湖泊相似，密度范围从 8.00×10 到 4.22×10 颗粒/公里，平均浓度为 1.89×10 颗粒/公里。微塑料的干沉降速率范围为 4 至 140 颗粒/米/天，平均值为 69 颗粒/米/天，秋季显著较高。湿沉降中微塑料的浓度范围为 0.006 至 0.050 颗粒/毫升，冬季最高，夏季最低。纤维状微塑料在湖泊水和大气沉降中均占主导地位。弗拉特黑德河入湖口附近采样点的微塑料密度较高，表明该河流是弗拉特黑德湖微塑料的重要来源。湖泊人口密集区附近的微塑料密度较高，且无纤维状微塑料比例较高，这意味着当地人类活动也影响了弗拉特黑德湖的微塑料。尽管干沉降中的微塑料年通量高于湿沉降，但相对较小的差异表明降水可能会增强微塑料的沉积。本研究结果表明，实施增加的控制措施，针对减少洗衣产生的微纤维和改善流域内塑料废物管理的整体水平，可能有助于控制弗拉特黑德湖中微塑料的水平。
