Ecotoxicological Assessment Tools

NEXT Program

Due to rapid industrial development, discharge of a wide range of chemicals into the environment has increased dramatically in recent years. The complexity of mixed chemical contaminants in the environment poses serious risks to ecosystem and human health due to the potential synergetic toxic effects of diverse chemical interactions, including long-term genotoxic effects. It is necessary to develop new assessment tools to adequately evaluate the overall toxic effects on ecosystems and predict the risks associated with mixed-chemical contaminated environments. The aim of this research is to develop ecotoxicological assessment tools to evaluate long-term genotoxicity by utilizing rapid microbial responses to perturbations detected by functional metagenomic and DNA adductomic approaches. Especially we focus on polluted environments impacted by mixed contaminants (organics, toxic elements, heavy metals) in the Asian region.

Geomicrobiology of Metalloids

Microorganisms inhabit almost every environment on the Earth’s surface and have influenced biogeochemical and mineralogical processes though time. Microbes play important roles in mineral dissolution and transformation processes, which would affect the mobility and toxicity of metalloids. We aim to identify and understand microbially-mediated arsenic and other related metal(loid)s transformation processes in the environments.

  • In Soda Lakes:

    Soda lakes are extreme habitats characterized by high pH, high salt content, and elevated concentrations of trace elements from volcanic origin. To gain insight regarding the role of microorganisms in the geochemical cycling of arsenic (As), we characterized the bacterial community associated with a soda lake in northern Mongolia.

  • In Mine Tailings:

    Antimony (Sb) is a naturally occurring toxic element and is considered to be a priority pollutant of interest by the USEPA. Although the concentrations of Sb in soils are generally low (<1 mg/kg), elevated levels of Sb have been released via mining activities and other anthropogenic activities due to its increasing industrial use. In the environment, Sb is commonly associated with arsenic (As) and both elements have similar chemistry and toxicity. Recent studies increased our knowledge on microbial roles in As transformations, while microbial-Sb interactions are still not well understood. We study microbial ecology of an old stibnite (Sb2S3) mine tailing area (Ichinokawa mine, Ehime, Japan) to gain insight into microbial roles in the geochemical cycling of Sb and As.

  • In Geothermal Environments:

    Geothermal waters often contain elevated levels of arsenic and other toxic elements, which could cause surface water contamination down gradient. We examined microbial arsenic oxidation in geothermal systems in Yellowstone National Park by incorporating genomics, transcriptomics and geochemical analyses.

Bioremediation Ecology

In the contaminated soil environments, various factors (e.g. soil type, temperature, contaminant mixtures) influence the microbial population selection. We work with naturally or anthropogenically-impacted systems as a model to examine interactions of physical-chemical changes (e.g. contaminant chemistry), biological changes (e.g. microbial community and function dynamics), and various environmental factors (e.g. temperature, geographical locations) for better understanding of bioremediation processes in situ.