Paleolimnological evidence for recent acidification of Big Moose Lake,Adirondack Mountains,N.Y. (USA) |
| |
Authors: | D F Charles D R Whitehead D R Engstrom B D Fry R A Hites S A Norton J S Owen L A Roll S C Schindler J P Smol A J Uutala J R White R J Wise |
| |
Affiliation: | (1) Department of Biology, Indiana University, Bloomington, IN 47405, USA;(2) Limnological Research Center, University of Minnesota, Minneapolis, MN 55455, USA;(3) School of Public and Environmental Affairs, Indiana University, Bloomington, IN 47405, USA;(4) Department of Geological Sciences, University of Maine, Orono, ME 04469, USA;(5) Faculty of Environmental and Forest Biology, SUNY College of Environmental Science and Forestry, Syracuse, NY 13210, USA;(6) Department of Biology, Queen's University, Kingston, Ontario, K7L 3N6, Canada;(7) Present address: Ecosystem Center, Marine Biological Laboratory, Woods Hole, MA 02543, USA |
| |
Abstract: | Big Moose L. has become significantly more acidic since the 1950s, based on paleolimnological analyses of sediment cores. Reconstruction of past lakewater pH using diatom assemblage data indicates that from prior to 1800 to ca. 1950, lakewater pH was about 5.8. After the mid-1950s, the inferred pH decreased steadily and relatively quickly to about 4.6. Alkalinity reconstructions indicate a decrease of about 30 eq · l-1 during the same period. There was a major shift in diatom assemblage composition, including a nearly total loss of euplanktonic taxa. Chrysophyte scale assemblages and chironomid (midge larvae remains also changed in a pattern indicating decreasing lakewater pH starting in the 1950s. Accumulation rates of total Ca, exchangeable and oxide Al, and other metals suggest recent lake-watershed acidification. Cores were dated using210Pb, pollen, and charcoal. Indicators of watershed change (deposition rates of Ti, Si, Al) do not suggest any major erosional events resulting from fires or logging. Accumulation rates of materials associated with combustion of fossil fuels (polycyclic aromatic hydrocarbons, coal and oil soot particles, some trace metals, and sulfur) are low until the late 1800s-early 1900s and increase relatively rapidly until the 1920s–1930s. Peak rates occurred between the late 1940s and about 1970, when rates declined.The recent decrease in pH of Big Moose L. cannot be accounted for by natural acidification or processes associated with watershed disturbance. The magnitude, rate and timing of the recent pH and alkalinity decreases, and their relationship to indicators of coal and oil combustion, indicate that the most reasonable explanation for the recent acidification is increased atmospheric deposition of strong acids derived from combustion of fossil fuels. |
| |
Keywords: | Adirondacks lake acidification acid precipitation paleolimnology diatoms chrysophytes chironomids geochemistry sulfur PAH |
本文献已被 SpringerLink 等数据库收录! |
|