Human Perturbation of C, N, and S Biogeochemical Cycles. Historical Studies with Stable Isotopes : Biologic Markers of Air-Pollution Stress and Damage in Forests. Workshop Papers

1989

S. 143-156

7 Abb., 43 Lit. Ang.

Unselbständiges Werk

200069322

Stable isotopes can serve as historical tracers of anthropogenic pollutants. For example, recent anthropogenic inputs of C, N, and S have altered insotopic compositions of tree rings, lake sediments, and components of the atmosphere. Some of these effects are small in magnitude, 1 0/00 or less, and difficult to detect without extensive sampling. Examples include carbon isotope changes in tree rings due to local pollution effects or as a result of global changes in atmospheric CO2 concentrations. Initial sulfur and nitrogen insotope studies suggest larger, more easily detectable changes of 2-7 0/00 in precipitation and lake cores. Sulfur isotope changes have been used to establish chronologies of anthropogenic sulfur inputs in some lake sediments. Nitrogen isotope studies of precipitation, lake cores, and tree rings are at a very early stage, but show promise for tracing human nitrogen additions from atmospheric deposition. Use of carbon, nitrogen and sulfur isotopes as historical pollution markers is appealing because they are natural tracers of, and cycle with, anthropogenic C, N, and S.