Is Earth really a sort of giant living organism as the Gaia hypothesis predicts? A new discovery made at the University of Maryland may provide a key to answering this question. This key of sulfur could allow scientists to unlock heretofore hidden interactions between ocean organisms, atmosphere, and land -- interactions that might provide evidence supporting this famous theory.
The Gaia hypothesis -- first articulated by James Lovelock and Lynn Margulis in the 1970s -- holds that Earth's physical and biological processes are inextricably connected to form a self-regulating, essentially sentient, system.
One of the early predictions of this hypothesis was that there should be a sulfur compound made by organisms in the oceans that was stable enough against oxidation in water to allow its transfer to the air. Either the sulfur compound itself, or its atmospheric oxidation product, would have to return sulfur from the sea to the land surfaces. The most likely candidate for this role was deemed to be dimethyl sulfide.
Newly published work done at the University of Maryland by first author Harry Oduro, together with UMD geochemist James Farquhar and marine biologist Kathryn Van Alstyne of Western Washington University, provides a tool for tracing and measuring the movement of sulfur through ocean organisms, the atmosphere and the land in ways that may help prove or disprove the controversial Gaia theory. Their study appears in this week's Online Early Edition of the Proceedings of the National Academy of Sciences (PNAS).
According to Oduro and his colleagues, this work presents the first direct measurements of the isotopic composition of dimethylsulfide and of its precursor dimethylsulfoniopropionate. These measurements reveal differences in the isotope ratios of these two sulfur compounds that are produced by macroalga and phytoplankton. These measurements (1) are linked to the compounds' metabolism by these ocean organi
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University of Maryland