Tidally driven export of dissolved organic carbon, total mercury, and methylmercury from a mangrove-dominated estuary

Environ Sci Technol. 2012 Feb 7;46(3):1371-8. doi: 10.1021/es2029137. Epub 2012 Jan 19.

Abstract

The flux of dissolved organic carbon (DOC) from mangrove swamps accounts for 10% of the global terrestrial flux of DOC to coastal oceans. Recent findings of high concentrations of mercury (Hg) and methylmercury (MeHg) in mangroves, in conjunction with the common co-occurrence of DOC and Hg species, have raised concerns that mercury fluxes may also be large. We used a novel approach to estimate export of DOC, Hg, and MeHg to coastal waters from a mangrove-dominated estuary in Everglades National Park (Florida, USA). Using in situ measurements of fluorescent dissolved organic matter as a proxy for DOC, filtered total Hg, and filtered MeHg, we estimated the DOC yield to be 180 (±12.6) g C m(-2) yr(-1), which is in the range of previously reported values. Although Hg and MeHg yields from tidal mangrove swamps have not been previously measured, our estimated yields of Hg species (28 ± 4.5 μg total Hg m(-2) yr(-1) and 3.1 ± 0.4 μg methyl Hg m(-2) yr(-1)) were five times greater than is typically reported for terrestrial wetlands. These results indicate that in addition to the well documented contributions of DOC, tidally driven export from mangroves represents a significant potential source of Hg and MeHg to nearby coastal waters.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Carbon / analysis*
  • Environmental Monitoring / methods
  • Environmental Monitoring / statistics & numerical data*
  • Florida
  • Fluorescence
  • Mercury / analysis*
  • Methylmercury Compounds / analysis*
  • Regression Analysis
  • Rhizophoraceae
  • Seawater / chemistry*
  • Spectrophotometry, Ultraviolet
  • Water Movements*
  • Water Pollution, Chemical / analysis*

Substances

  • Methylmercury Compounds
  • Carbon
  • Mercury