Metal Geochemistry of a Brackish Lake: Étang Saumâtre, Haiti

Etang Saumâtre (also known as Lac Azuei, Lago del Fondo, or Yainagua) is a brackish lake located in eastern Haiti. Sources of irrigation and drinking water for the surrounding communities in Thomazeau, Ganthier, and Fond Parisien are freshwater springs and shallow wells tapping the complex fractured aquifer system surrounding Etang Saumâtre. In some groundwater samples, we found concentrations of trace metals exceeding World Health Organization guideline values. Lake sediment trace metal concentrations were also high. For example, chromium (Cr) ranged from 26.24 to 198.44 mg/kg, exceeding the USEPA sediment quality guideline value for heavily polluted. High concentrations of potentially toxic trace metals in both lake sediments and groundwater suggest that the population relying on this lake for drinking water, irrigation, and subsistence fishing may be at risk for metal-induced health effects. By understanding the geochemical behavior of redox-sensitive trace metals such as Cr, in the context of limnology and long-term fate and transport within the system, our results provide unique insights into the geochemical controls on remobilization of redox metals from the sediments and the potential impact of future environmental change on the sediment and water quality in this system.