COI Funded Project: Development of a radon/methane/nitrate mapping system for a large scale assessment of submarine groundwater discharge and non-point source pollution in the coastal zone


Project Funded: 2006

Key Words: Submarine Groundwater Discharge, Coastal Pollution, Geochemical Tracers

Submarine groundwater discharge is a flow of fresh groundwater and recirculated seawater from land into the coastal zone and is recognized as a pathway of dissolved components from land to the oceans. The dissolved components often include pollutants from anthropogenic sources, for example nutrients from sewer systems or agricultural activities on land. The distribution of these sources along the coastline is not uniform, and the same is true about the magnitude of groundwater discharge. Consequently we are confronted with variable non-point source pollution on the land-ocean interface.

In order to evaluate submarine groundwater discharge and its role in non-point source pollution on a large scale (many kilometers of shoreline) we will construct a radon-methanenitrate surveying system. The surveying system is based on measurements of natural constituents of groundwater: radon and methane in coastal waters. These occur in groundwater in elevated concentrations in comparison to sea water therefore can be used as tracers of submarine groundwater discharge. Areas with high concentrations of radon and methane coupled with high nitrate values in coastal waters can then be investigated in more detail to estimate groundwater and nitrate fluxes. The promise of this technique is that we can map many kilometers of shoreline in a short time and locate areas with significant submarine groundwater discharge and non-point source pollution. Doing the same survey both in dry and wet seasons also allows us to study the seasonality of groundwater and nitrate fluxes.