Peatlands as source of acid rain.

Peatlands as source of acid rain

Evergreens and glaciers lend southeast Alaska a pristine appeal. That's why geographer Lee F. Klinger was puzzled when he measure extremely acidic rainwater in this region. While normal rainwater has a pH about 5.6, measured values as low as 3.6 during the summers and falls of 1986 and 1987.

Other researchers have discovered acidic rainwater in remote sites and traced the acids back to sulfur compounds emitted by oceanic organisms. Klinger, who works at the National Center for Atmospheric Research in Boulder, Colo., says the oceans may offer a partial explanation of the acids, but they don't tell the whole story. Analysis of the rainwater shows that, in addition to sulfuric acid, it contains certain organic acids that can only come from land sources, he reports.

Where, then, do those acids originate? Klinger suggests peatlands as an answer. Atmospheric patterns in the area indicate that the regions with the worst acid rain lie downwind from peatlands. Klinger tested the gases emitted by peatlands and found high levels of terpenes, isoprenes and other chemicals that could serve as sources of the organic acids.

Last year, Klinger reported that acid-loving mosses hasten the death of trees, in part by acidifying their immediate environment (SN: 4/30/88, p. 285). The work in southeast Alaska suggests that peatlands -- abundant in mosses -- kill forests over a large area by creating acid rain. This process, he says, promotes the spread of mosses and develops more peatland.