Subsurface Pathways of Contaminants to Coastal Waters: Effects of Oceanic Oscillations

摘要

Submarine groundwater discharge (SGD) has been identified by the International Geosphere-Biosphere Programme as an im-portant contamination source for coastal marine and estuarine en-vironments. Inputs of land-derived contaminants associated with SGD cause serious threats to the near-shore ecosystem. Water exchange driven by oceanic oscillations such as tides and waves at the shore contributes to SGD significantly. Moreover, the oceanic oscillations modify the near-shore groundwater flow and induce mixing of fresh groundwater with seawater. These processes affect not only the transport but also the chemical reactions of the con-taminants in the near-shore aquifer prior to the discharge. In this chapter, we first review studies of costal groundwater responses to tides and waves, focussing on analytical solutions of the groundwa-ter table fluctuations. We then discuss the effects of the groundwa-ter fluctuations on the fate of chemicals in the near-shore aquifer and chemical fluxes to coastal water. These discussions are based on several on-going studies aiming to improve the understanding and quantification of subsurface pathways and fluxes of chemicals to coastal environments.