Accumulation of Refractory Dissolved Organic Nitrogen in Sediments Porewater
Marine sediments are globally significant sources of dissolved organic matter (DOM) to the water column. However, their role in the oceanic DOM cycle is unclear, because the molecular composition and reactivity of the DOM that is produced in the sediments - and supports a benthic flux - remains largely unexplored. The connection between benthic DOM dynamics and the oceanic DOM cycle remains elusive because we are lacking information about sediment DOM at the molecular level. Our long-term goal is to gain a mechanistic understanding of organic matter degradation and accumulation through examination of pore-water DOM composition and dynamics. We are currently investigating the microbial alteration of peptides as a mechanism for the production of refractory DOM in anoxic sediments.
One of the most challenging questions prohibiting us from fully understand our marine ecosystem is predicting how aquatic microbial communities respond and tolerate environmental stresses. In our lab, we address this question by studying the changes in the metabolomics profiles of these microbes which could give us more details about the interactions between these species and their environment, and for the identification of the chemical mechanisms that enable these species to tolerate environmental stresses especially as metabolites reflect and amplify the activities at a functional level, i.e., the true phenotype.
Degradation and transformation of organic pollutants in Aquatic Environment
Endocrine-disrupting compounds (EDCs) are a group of organic contaminants that have been identified in surface waters worldwide and have the potential to disrupt the endocrine system of aquatic organisms. ECDs include plasticizers, steroidal hormones, alkylphenol nonionic surfactant degradation products, and pharmaceuticals. Many studies have shown a relationship between bioaccumulation of EDCs in vertebrates and alteration of immune functions, increases birth defects, and an upsurge in incidences of breast, testicle, and prostate cancers and heart diseases. The fate, transport, and biological effects of EDCs in surface waters are dependent upon a number of physicals (dilution, advection, and dispersion), chemical (sorption and volatilization), photochemical (photolysis), and biological (transformation, and uptake) processes. The relative importance of these processes in removing EDCs is still largely unknown.