Iron-induced changes in oceanic sulfur biogeochemistry

The IronEx studies showed that in situ addition of iron in "high-nitrate-low-chlorophyll'' regions of the Pacific Ocean increased the amount of dimethylsulfide (DMS) available for emission to the atmosphere. Here we show results from two similar experiments in the Southern Ocean ( SOIREE, 61 degreesS and EisenEx, 48 degreesS). DMS concentrations increased up to 8-fold and we find marked similarity in the changes in dimethylsulfonioproprionate ( the algal precursor of DMS) during the Pacific and Southern Ocean experiments, despite large differences in algal community, temperature, light and mixed layer depth. These results may lend support to a link between paleo-climatic variations in iron availability, emissions of DMS and, hence, atmospheric albedo and global temperature. Further, if large-scale iron fertilization is to be considered as a strategy for mitigating the increase in man-made CO(2) in the atmosphere then the climatic affects of DMS and a number of other trace gases must be assessed.