Risk assessment and identification of factors influencing the historical concentrations of microcystin in Lake Taihu, China

Chen Cheng; Alan D Steinman; Kaiye Zhang; Qi Lin; Qingju Xue; Xing Wang; Liqiang Xie

doi:10.1016/j.jes.2022.03.043

Risk assessment and identification of factors influencing the historical concentrations of microcystin in Lake Taihu, China

J Environ Sci (China). 2023 May:127:1-14. doi: 10.1016/j.jes.2022.03.043. Epub 2022 Apr 12.

Authors

Chen Cheng¹, Alan D Steinman², Kaiye Zhang³, Qi Lin³, Qingju Xue³, Xing Wang⁴, Liqiang Xie⁵

Affiliations

¹ State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
² Annis Water Resources Institute, Grand Valley State University, 740 West Shoreline Drive, Muskegon, MI, USA.
³ State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
⁴ National Engineering Laboratory for Lake Pollution Control and Ecological Restoration, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; State Environmental Protection Key Laboratory of Drinking Water Source Protection, Chinese Research Academy of Environmental Sciences, Beijing 100012, China. Electronic address: wx19830411@21cn.com.
⁵ State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China. Electronic address: lqxie@niglas.ac.cn.

PMID: 36522044
DOI: 10.1016/j.jes.2022.03.043

Abstract

Understanding the history of microcystins (MCs) pollution in large lakes can help inform future lake management. We collected sediment cores from Lake Taihu to: investigate the long-term record of MCs (MC-LR, MC-YR, and MC-RR), explore the main environmental drivers of MCs, and assess their public health and ecological risks. Results showed that MCs content in all cores increased over time. The core from north Taihu had the highest MC concentrations, with an average total MCs (sum of MC-LR, MC-YR, and MC-RR = TMCs) content of (74.31±328.55) ng/g. The core from eastern Taihu showed the lowest average TMCs content of (2.91±3.95) ng/g. PCA showed that sediment MCs at the three sites were positively correlated with sediment chlorophyll-a. MC-LR and MC-YR in northern and western Taihu negatively correlated with both the sediment total organic carbon/sediment total nitrogen ratio (STOC/STN) and water nitrate (NO₃^--N) concentration, but three MC congeners at eastern Taihu showed positive correlations with water orthophosphate (PO₄^3--P), NO₃^--N, and STOC/STN. Generalized additive model analysis at each site revealed that NO₃^--N was the main TMCs driver in northern and western Taihu where phytoplankton dominated, whereas PO₄^3--P was the main TMCs driver in eastern Taihu where macrophytes dominated. At the whole lake scale, total phosphorus (TP) and PO₄^3--P were the most important environmental drivers influencing MCs; TP explained 47.4%, 44.2%, and 47.6% while orthophosphate explained 34.8%, 31.2%, and 34.7% of the deviance on TMCs, MC-LR, and MC-YR, respectively. NO₃^--N also showed a strong effect on MCs variation, especially on MC-YR. Risk assessment showed that both ecological and public health risk has increased in recent years. We conclude that while control of phosphorus and nitrogen input should be a major focus for future lake management, lake zone-specific management strategies may also be important.

Keywords: Lake Taihu; Microcystins; Nitrate; Orthophosphate; Pollution history; Risk assessment.

MeSH terms

China
Environmental Monitoring*
Microcystins* / analysis
Nitrogen / analysis
Phosphates / analysis
Phosphorus / analysis
Risk Assessment
Water / analysis

Substances

Microcystins
Phosphorus
Nitrogen
Phosphates
Water