CHBr3, CH2Br2, and CHClBr2 in U.S. coastal waters during the Gulf of Mexico and East Coast Carbon cruise

Brominated very short-lived substances (VSLSs) such as bromoform (CHBr3), dibromomethane (CH2Br2), and chlorodibromomethane (CHClBr2) are receiving increasing attention, due to their important role in tropospheric and lower stratospheric ozone (O-3) chemistry. These brominated VSLSs were measured in air and surface water during the Gulf of Mexico and East Coast Carbon (GOMECC) cruise in the summer of 2007. Mean atmospheric mixing ratios for CHBr3, CH2Br2 and CHClBr2 for the entire cruise were 14.6 (0.7 to 138.3) ppt, 2.8 (0.5 to 13.2) ppt, and 0.5 (0.03 to 3.2) ppt, respectively; and mean sea-surface water concentrations were 66.0 (4.4 to 1724.8) pmol L-1, 10.6 (1.9 to 153.8) pmol L-1, and 1.0 (0.1 to 17.2) pmol L-1, respectively. These compounds were supersaturated almost everywhere in the study region, except a few locations in the Florida Straits and along the east coast of Florida, where negative saturation anomalies and fluxes were observed. Mean net fluxes observed during the GOMECC cruise for CHBr3, CH2Br2, and CHClBr2 were 47.6 (-25.4 to 1056.3) nmol m(-2) d(-1), 9.7 (-0.5 to 112.3) nmol m(-2) d(-1), and 0.8 (-1.2 to 10.8) nmol m(-2) d(-1), respectively. The net fluxes for these polybrominated compounds from the coastally influenced waters (bottom depth <= 200 m) are significantly higher than the net fluxes observed in the open ocean ( bottom depth >200 m).