Radium mass-balance in Jamaica Bay, NY: Evidence for a substantial flux of submarine groundwater |
| |
| Authors: | Aaron J Beck John P Rapaglia J Kirk Cochran Henry J Bokuniewicz |
| |
| Institution: | aMarine Sciences Research Center, Stony Brook University, Stony Brook, NY, 11794-5000, USA |
| |
| Abstract: | A mass balance for the naturally-occurring radium isotopes (224Ra, 223Ra, 228Ra, and 226Ra) in Jamaica Bay, NY, was conducted by directly estimating the individual Ra contributions of wastewater discharge, diffusion from fine-grained subtidal sediments, water percolation through marshes, desorption from resuspended particles, and water exchange at the inlet. The mass balance revealed a major unknown source term accounting for 19–71% of the total Ra input, which could only be resolved by invoking a source from submarine groundwater. Shallow (< 2 m depth) groundwater from permeable sediments in Jamaica Bay was brackish and enriched in Ra relative to surface bay waters by over two orders of magnitude. To balance Ra fluxes, a submarine groundwater input of 0.8 × 109–9.0 × 109 L d− 1 was required. This flux was similar for all four isotopes, with individual estimates varying by less than a factor of 2. Our calculated groundwater flux was 6- to 70-fold higher than the fresh groundwater discharge to the bay estimated by hydrological methods, but closely matched direct flow rates measured with seepage meters. This suggests that a substantial portion of the discharge consisted of recirculated seawater. The magnitude of submarine groundwater discharge varied seasonally, in the order: summer > autumn > spring. Chemical analyses suggest that the recirculated seawater component of submarine groundwater delivers as much dissolved nitrogen to the bay as the fresh groundwater flux. |
| |
| Keywords: | Ground water Radium isotopes Estuarine chemistry Submarine groundwater discharge SGD New York Jamaica Bay |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
