Spatiotemporal Variations in Dissolved Elemental Mercury in the River-Dominated and Monsoon-Influenced East China Sea: Drivers, Budgets, and Implications
Journal
Environmental Science and Technology
Journal Volume
54
Journal Issue
7
Pages
3988-3995
Date Issued
2020
Author(s)
Abstract
Distinct spatiotemporal distributions of sea surface dissolved elemental mercury (DEM) and its air-sea exchange flux were observed in the river-dominated and monsoon-influenced East China Sea (ECS). Spatially, DEM concentrations were higher in the nearshore Changjiang diluted water (90 ± 20 to 260 ± 40 fM) than in the offshore Kuroshio water (60 ± 10 to 160 ± 40 fM) and correlated with salinity and total Hg concentrations, suggesting that the total Hg discharged from the Changjiang river is a controlling factor. In summer, monsoon-driven coastal upwelling formed a transient nearshore water mass with very elevated DEM concentrations (290 ± 20 to 320 ± 70 fM). Seasonally, DEM concentrations in all water masses were the highest in summer (120 ± 30 to 320 ± 70 fM). Estimated rate coefficients for DEM production varied seasonally and strongly correlated with sea surface temperature (SST). Hg0 evasion fluxes also peaked in summer (670 ± 380 pmol m-2 day-1), while in winter, DEM was close to equilibrium with gaseous elemental mercury in the atmosphere. Based on the air-sea Hg fluxes for all four seasons from this study and regional atmospheric deposition fluxes from others, we conclude that the ECS is a net sink of Hg annually, but it is a source of Hg to the atmosphere in summer. Moreover, the contribution of the ECS to Hg evasion may increase as a result of flood-associated high Changjiang discharge and rising SST. Copyright © 2020 American Chemical Society.
Other Subjects
Atmospheric movements; Atmospheric thermodynamics; Budget control; Meteorological problems; Ocean currents; Offshore oil well production; Atmospheric depositions; Coastal upwelling; Controlling factors; Gaseous elemental mercury; Rate coefficients; Sea surface temperature (SST); Spatio-temporal variation; Spatiotemporal distributions; Rivers; dissolved organic matter; mercury; air-sea interaction; atmospheric deposition; chemical element; concentration (composition); dissolved matter; flux measurement; mercury (element); monsoon; nutrient budget; river discharge; sea surface temperature; spatiotemporal analysis; upwelling; Article; atmospheric deposition; boundary layer; concentration (parameter); controlled study; East China Sea; monsoon climate; river; sea surface temperature; seasonal variation; solar radiation; air pollutant; China; environmental monitoring; river; season; water pollutant; China; East China Sea; Kuroshio Current; Pacific Ocean; Yangtze Basin; Air Pollutants; China; Environmental Monitoring; Mercury; Rivers; Seasons; Water Pollutants, Chemical
Type
journal article