The COVID-19 Anthropause and Its Hydrochemical Impacts: A Case Study of Chonburi Coast, Thailand
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Abstract
This study investigates the impact of COVID-19 lockdown measures on coastal ecosystems in Chonburi Province, Thailand. A comparative analysis of water and sediment quality parameters from 10 sampling stations was conducted between the pre-pandemic (2017–2019) and pandemic (2020–2021) periods. The lockdown period showed statistically significant improvements (p<0.05) across multiple water quality parameters: a 27% increase in transparency, a 29% reduction in total suspended solids, and a 42% decrease in PO₄³⁻-P concentrations in surface water. Concurrently, bottom water showed reductions of 51% and 43% in NO₂⁻+NO₃⁻-N and PO₄³⁻-P levels, respectively. Sedimentary parameters similarly improved, showing reductions of 10%, 23%, and 9% in AVS, Si(OH)₄-Si, and PO₄³⁻-P. Counterintuitively, phytoplankton biomass (Chl a) increased dramatically (101–116%), which is attributable to improved light availability (27% higher transparency) and substantial nutrient fluxes from sediments, where NH₄⁺-N and PO₄³⁻-P concentrations exceeded bottom water levels by 90- and 213-fold, respectively. Spatial analysis revealed stronger fluvial influences near river mouths compared to distal areas. The 84% reduction in tourist numbers significantly decreased nutrient inputs (p<0.05; based on the pre-lockdown correlation), though persistent N:P imbalances (surface 17:1, bottom 29:1) and sedimentary nutrient reservoirs maintained eutrophic conditions. These findings demonstrate the rapid responsiveness of coastal ecosystems to reduced anthropogenic pressure. They further underscore the critical need for implementing targeted sediment management strategies in areas with high land-based runoff to achieve sustainable water quality improvements.
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