Indicating atmospheric sulfur by means of S-isotope in leaves of the plane, osmanthus and camphor trees

Foliar δ34S values of three soil-growing plant species (Platanus Orientalis L., Osmanthus fragrans L. and Cinnamomum camphora) have been analyzed to indicate atmospheric sulfur. The foliar δ34S values of the three plant species averaged −3.11 ± 1.94‰, similar to those of both soil sulfur (−3.73 ± 1.04‰) and rainwater sulfate (−3.07 ± 2.74‰). This may indicate that little isotopic fractionation had taken place in the process of sulfur uptake by root or leaves. The δ34S values changed little in the transition from mature leaves to old/senescing leaves for both the plane tree and the osmanthus tree, suggestive of little isotope effect during sulfur redistribution in plant tissues. Significantly linear correlation between δ34S values of leaves and rainwater sulfate for the plane and osmanthus trees allowed the tracing of temporal variations of atmospheric sulfur by means of foliar sulfur isotope, while foliage δ34S values of the camphor is not an effective indicator of atmospheric sulfur.

► The δ34S values in plant leaves were similar to the average of rainwater.
► Little isotope effect was found during sulfur uptake by plant leaves.
► The foliage δ34S values are useful to indicate atmospheric sulfur.