Biogeochemical cycling of halogenated organic compounds in the ocean: Current progress and future directions

Halogenated Organic Compounds (HOCs) are a class of refractory organic compounds produced in large quantities in the ocean, and some compounds can even persist over millions of years. The processes of production, transportation, and burial of HOCs, as well as the transformation and degradation of these compounds by microorganisms, are important parts of the biogeochemical cycling of carbon and halogen in the ocean. Dehalogenation microorganisms and dehalogenation pathways are prevalent in the deep-sea and the subseafloor biosphere, indicating the significance of HOCs metabolism in the ocean and interior of the earth. This paper reviews the current understanding on the generation, distribution, and transport of HOCs, as well as microbial mediated HOC degradation processes in the ocean. The preliminarily model for biogeochemical cycle of marine HOCs is summarized based on the existing knowledge. The research gaps and limitations are identified and future directions are also discussed.