mole_content_of_organic_mercury_in_sea_floor_surface_sediment mol m-2 [MLM2] "Content" indicates a quantity per unit area. "Organic mercury" describes a family of chemical species in which mercury atoms covalently bonded to carbon-containing groups, forming organomercury compounds (e.g., methylmercury (MeHg), monomethylmercury (MMHg), dimethylmercury (DMHg), ethylmercury (EtHg)). The surface called "sea floor" means the lower boundary of the ocean.