δ34S variations in vegetation and soil exposed to intense biogenic sulphide emissions near Paige mountain,N.W.T., Canada

Sulphur isotope abundances demonstrate that natural emissions of biogenic H₂S and its oxidation products from springs near Paige Mountain, N.W.T., Canada, can be incorporated into surrounding soil and vegetation. δ³⁴S values as low as ? 33‰ for soil and vegetation are the result of dominant uptake of biogenic atmospheric compounds. In contrast, vegetation on a gypsum outcrop remote from the springs, has δ³⁴S values as high as + 26‰ indicating nearly exclusive derivation of S from the soil. Near the springs, soil with vegetative cover is less depleted in ³⁴S than soil lacking cover. Lower needles on a Black Spruce were found to be less depleted in ³⁴S than the upper needles. These observations suggest that upper foliage exerts a canopy effect on lower foliage and in turn, interception by vegetation reduces the flux of atmospheric S compounds to the soil. Clearly, natural emissions of S compounds can interfere in studies of long range transport of industrial emissions; S isotope analyses might identify such interferences and reduce the chance of misinterpretation.