BIOGEOCHEMISTRY OF HYDROCARBON IMPACTED ARCTIC WATERS

Microbial mats, composed of cyanobacteria, algaes and non-photosynthetic bacteria, appear where arctic surface waters are contaminated with hydrocarbon impacted groundwater and sediments. These mats may have potential for remediation of hydrocarbons. Hydrocarbon impacted groundwater and sediments are usually anaerobic or anoxic in comparison to unimpacted arctic surface waters. The higher dissolved carbon dioxide related to, and often present in, hydrocarbon impacted groundwater and sediments, may benefit photosynthetic cyanobacteria and diatom found in oligotrophic, lower alkalinity arctic waters. Redox fronts, conducive to the formation of bacterial slime consortia, also occur where oxygen depleted and hydrocarbon impacted waters enter arctic streams. Potentially, anaerobic and aerobic bacteria can take advantage of both the hydrocarbon substrate and the nitrogen fixing abilities of the cyanobacteria. The toxicity of the impacted groundwater may also kill off the zooplankton predators of bacteria and algae. A combination of several or all of these factors could explain the apparent dominance of microbial mats in contaminated arctic streams and waters