The spatial distribution and abundance of microplastics in lake waters and ice during ice-free and ice-covered periods

Yu Liu; Xiaohong Shi; Sheng Zhang; Junping Lu; Wenbao Li; Biao Sun; Shengnan Zhao; Dingwen Yao; Jussi Huotari

doi:10.1016/j.envpol.2023.121268

The spatial distribution and abundance of microplastics in lake waters and ice during ice-free and ice-covered periods

Environ Pollut. 2023 Apr 15:323:121268. doi: 10.1016/j.envpol.2023.121268. Epub 2023 Feb 11.

Authors

Yu Liu¹, Xiaohong Shi², Sheng Zhang¹, Junping Lu¹, Wenbao Li¹, Biao Sun¹, Shengnan Zhao¹, Dingwen Yao³, Jussi Huotari⁴

Affiliations

¹ Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot, 010018, China; Autonomous Region Collaborative Innovation Center for Integrated Management of Water Resources and Water Environment in the Inner Mongolia Reaches of the Yellow River, Hohhot, 010018, China.
² Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot, 010018, China; Autonomous Region Collaborative Innovation Center for Integrated Management of Water Resources and Water Environment in the Inner Mongolia Reaches of the Yellow River, Hohhot, 010018, China. Electronic address: shixiaohong@imau.edu.cn.
³ Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot, 010018, China.
⁴ Lammi Biological Station, Ecosystems and Environment Research Programme, Faculty of Biological and Environmental Sciences, Helsinki University, Lammi, FI-16900, Finland.

PMID: 36780975
DOI: 10.1016/j.envpol.2023.121268

Abstract

Understanding the spatial distribution and characteristics of microplastics (MPs) in lake waters is essential to assessing and addressing lacustrine MP pollution. This study investigated how lake ice affects the abundance, spatial distribution, and characteristics (size, shape) of MPs in Lake Ulansuhai by analyzing samples collected at ten sites uniformly distributed throughout the lake during ice-free and ice-covered periods. The abundance of MPs ranged between 204 ± 28 and 1224 ± 185 n·L^-1 in lake waters during the ice-free period, and from 34 ± 8 to 216 ± 21 n·L^-1 and 269 ± 84 to 915 ± 117 n·L^-1 in water and ice during the ice-covered period, respectively. During the ice-covered period, MPs were 2.74-8.14 times higher in the ice than in water beneath the ice. Ice formation decreased MP abundance in lake waters, in part, by incorporating a relatively high percentage of MPs into the ice mass during freezing and by inhibiting atmospheric MPs from reaching the lake waters. The abundance of MPs in the water during the ice-free period was 4.50-11.30 times greater than during the ice-covered period. Seasonal variations in MP shape also occurred; the proportion of fibrous MPs in water decreased during the ice-covered period. Variations in MP abundance were partly due to differences in sedimentation rates; the settling of fibrous MPs is slower, making it easier for them to be captured during the formation of surface ice. Spatially, MPs were uniformly distributed during the ice-free period, but exhibited a spatially distinct pattern during ice-covered periods, when MPs in lake waters were higher in the northeast and lower in the southwest portions of the lake. During the ice-free period, small MPs (0.05-0.5 mm) were more likely to move with currents in the lake, whereas water velocities were reduced by ice formation, allowing small MPs to accumulate near the lake inlet.

Keywords: Cold lacustrine ecosystems; Lake ulansuhai; Microplastics; Spatial-temporal variations.

MeSH terms

Environmental Monitoring
Lakes
Microplastics*
Plastics
Water
Water Pollutants, Chemical* / analysis

Substances

Microplastics
Plastics
Water Pollutants, Chemical
Water