The Global Biogeochemical Sulphur Cycle*

The major sulphur fluxes of both natural and anthropogenic origin have been assessed by generalization of the results of our studies and data available in the literature. Annually about 120 Tg S are extracted by man from the lithosphere in fossil fuels and sulphur-containing raw materials for the chemical industry. Of this amount 70 Tg S are emitted to the atmosphere with the products of fuel combustion. About half of the remaining 50 Tg S directly enters rivers with sewage and residual waters, and another part is applied with fertilizers to agricultural land. Parallel with anthropogenic sulphur, volcanic gases contribute markedly to the atmospheric sulphur cycle over continents where, according to our data, the sulphur flux amounts to 29 Tg yr-l . The major transfer of sulphur from continents to the ocean is brought about by river runoff with an annual sulphur load of 224 Tg in which the sulphur of anthropogenic pollution accounts for 109 Tg. Tremendous amounts of sulphur are involved in processes of internal turnover betwe~n ~he oceanic atmosphere and its waters. The total flux of various sulphur forms (organic, sulphate, and pyrite) from oceanic water to sediments and further to the lithosphere amounts to 130 Tg yr-l ; Thus, our estimates point to the fact that the anthropogenic sulphur fluxes to the atmosphere and hydrosphere have reached a level comparable with that of natural fluxes. The analysis of prospects for future uses of various fossil fuels and fertilizers suggests that by the end of this century the anthropogenic sulphur fluxes will increase notably in all regions of the world. The present report is a preliminary account of the work of Sovietscientists on preparing the SCOPEreport as part of project 1.3, 'The globalbiogeochemicalsulphur cycle'. The resolution on conducting this work wasadopted at the Parismeeting of the SCOPEExecutive Committee in May 1977 and supported by the Open Session of the SCOPEExecutive Committee in London (October 1977). *The work on this project was carried out with the assistance of Prof. V. A. Grinenko and Drs. A. A. Migdisov (Institute of Geochemistry and Analytical Chemistry), A. Yu. Lein (Institute of Biochemistry and Physiology of Microorganisms), A. G. Ryaboshapko (Institute of Applied Geophysics), I. I. Volkov and A. G. Rozanov (Institute of Oceanology), and A. L. Rabinovich (HydrochemistIY Institute).