HR: 13:40h
AN: V13F-01 INVITED    [Abstracts]
TI: The changing role of dust in biogeochemical cycling
AU: * Neff, J C
EM: neffjc@colorado.edu
AF: University of Colorado, Geosciences Dept, CB 399, Boulder, CO 80309, United States
AU: Reynolds, R L
EM: richard.reynolds@usgs.gov
AF: US Geologic Survey, ESP Team, MS 980, Denver Federal Center, Lakewood, CO 80225, United States
AU: Farmer, G L
EM: farmer@buffmail.colorado.edu
AF: University of Colorado, Geosciences Dept, CB 399, Boulder, CO 80309, United States
AU: Reheis, M
EM: mreheis@usgs.gov
AF: US Geologic Survey, ESP Team, MS 980, Denver Federal Center, Lakewood, CO 80225, United States
AB: Dust emission and deposition have the potential to deplete and enrich ecosystems of mineral resources essential to life. In many parts of the world, and particularly in semi-arid settings, wind erosion of soils and the subsequent long-distance transport and deposition of mineral aerosols play a basic role in soil composition and processes, including the production of essential plant nutrients through weathering. Although the long-term role of dust in the development of soils is reasonably well understood, the effects of recent dust emission and deposition on ecosystems are not. Recent work on ecosystems around the world has highlighted the fundamental importance of contemporary wind erosion and dust deposition in biogeochemical cycling. In the western U.S., studies of Sr and Nd isotopes, elemental concentrations, and magnetic properties elucidate the role of dust in recent soil development and soil loss by wind erosion related to land-use change. In the arid landscapes in and around Canyonlands National Park (Utah), these techniques provide insight into the development of soils in stable settings where human activities have been minimal but the loss of soil in areas affected by grazing and recreational activities. In stable settings of the central Colorado Plateau (Utah), dust deposition is responsible for a large proportion (as much as 20 percent) of surface soil mass and elemental content. In contrast, wind erosion is responsible for large losses of nutrients and surface soil of nearby, closely similar geomorphic settings disturbed by human activity. In the San Juan Mountains (Colorado) downwind of the Colorado Plateau, Nd and Sr isotopes in dust and lake sediments provide evidence for large increases in dust deposition during the 19th and 20th century compared to records from the middle to late Holocene. The recent enhancement in dust deposition is also responsible for increased loading of many elements, including essential nutrients that may influence ecological processes. In settings of continued dust accumulation over the past ca. 150 years, geochemical results point to changes in dust composition, particularly in some trace metals and P. The apparent, human-driven change in the amount and composition of emitted dusts has implications for both our understanding and prediction of mineralization processes across a range of landscapes.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 0486 Soils/pedology (1865)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting