Abstract
We present the first reported measurements of volatile iodocarbon production by biogenic marine aggregates. Iodomethane (CH 3 I), iodoethane (C 2 H 5 I), 2‐iodopropane (CH 3 CHICH 3 ), and 1‐iodopropane (CH 3 CH 2 CH 2 I) concentrations were determined in incubations of aggregates formed by concentrating the >53 µm fraction of the plankton during a field campaign in the Celtic Sea. All four iodocarbons increased significantly in concentration in the aggregate incubations relative to filtered seawater controls. Maximum production rates ranged from 0.01 pmol L −1 h −1 for CH 3 CHICH 3 to 0.31 pmol L −1 h −1 for C 2 H 5 I. Accompanying pheopigment and bacterial heterotrophic production suggest that the processes taking place on the aggregates studied were a good representation of those known to occur on natural marine particles. We also report iodocarbon production rates observed in natural marine aggregates, including a diatom mucilage collected in the Celtic Sea and phytodetritus sampled from Kongsfjord in the Arctic. Detrital particles could be hotspots of iodocarbon production in the marine environment.