PRESCRIBED BURNING AND MECHANICAL THINNING ARE ESSENTIAL FOREST MANAGEMENT PRACTICES IN THE SOUTHEASTERN U.S. AGAINST SOUTHERN PINE BEETLE ATTACK AND WILDFIRES. HOWEVER, ALTERATION OF NATURALLY DEPOSITED POOL OF TOXIC METAL - MERCURY (HG) IN FORESTS WOULD HAVE UNKNOWN CONSEQUENCES ON ITS BIOGEOCHEMICAL CYCLING, AND MORE IMPORTANTLY THIS MAY ALTER THE RISK OF HG POSED TO THE ENVIRONMENT. WE CONTEND IN THIS PROPOSAL THAT PRESCRIBED BURNING WOULD INCREASE THE UNREACTIVE POOL OF HG ASSOCIATED WITH THE CHARRED BIOMASS AND SUBSEQUENTLY REDUCE HG BIOAVAILABILITY IN DOWNSTREAM HABITATS THROUGH SORPTION MECHANISM, AND THUS LOWERING HG METHYLATION AND BIOACCUMULATION. IN CONTRAST, MECHANICAL THINNING WOULD INCREASE HG BIOAVAILABILITY VIA INCREASING THE AMOUNT OF DETRITUS ON THE FOREST FLOOR, AND POTENTIALLY STIMULATE MICROBIAL HG METHYLATION AND BIOACCUMULATION. WE PROPOSE A FOUR-YEAR PROJECT, INVOLVING CONTROLLED FIELD STUDIES, LABORATORY INCUBATION EXPERIMENTS, AND WATERSHED-SCALE INVESTIGATIONS ALONG A GEOGRAPHIC GRADIENT IN CAROLINAS, TO FULLY EVALUATE FUEL REDUCTION PRACTICES ON THE STORAGE, TRANSPORT, TRANSFORMATION, AND BIOACCUMULATION OF TOXIC HG. FOREST FLOOR MATERIALS WILL BE COLLECTED FROM REPLICATED EXPERIMENTAL WATERSHEDS, AND WILL BE INCUBATED UNDER FIELD CONDITIONS TO EXAMINE THEIR POTENTIAL TO LEACH HG VIA RUNOFF. EXTENSIVE SAMPLING WILL BE PERFORMED TO EXAMINE AQUEOUS TRANSPORT AND SEDIMENT DEPOSITION OF THESE UPSTREAM POOLS OF ORGANIC MATTER, BLACK CARBON, AND HG. FINALLY, HG METHYLATION HOTSPOTS AND HG BIOACCUMULATION IN RESIDENT FOOD WEBS WILL BE CHARACTERIZED. A BOX MODEL DESCRIBING PRODUCTION OF METHYLMERCURY, TOXIC FORM OF MERCURY, IN FORESTED ECOSYSTEMS UNDER DIFFERENT FOREST MANAGEMENT PRACTICES WILL BE DEVELOPED.