Chemical Weathering Rates and Landscape Development: The Role of Hydrology, Climate, Vegetation, and Anthropogenic Activities

Lyons, W.B., D.T. Long, C. Bowser, G. McPherson, and W. McDowell

Presented at the All Scientist Meeting (1998-07-21 to 1998-07-22 )

Weathering is the physical and chemical breakdown of rocks. Chemical weathering involves the dissolution, alteration, and replacement of minerals unstable at the Earth’s surface and/or precipitation of new minerals that are stable. The products of chemical weathering (e.g., soils and solutes) and processes (CO2 cycling) are important to the ecology of systems and to issues of global climate change. Although it is well known that the rates of chemical weathering are a function of the chemistry of the parent material, climate (temperature and precipitation), biological activity, and hydrology, there are still many questions as to how all of these factors interrelate to control weathering rates.The objective of this long-term research is to investigate the roles of hydrology, climate, vegetation, and anthropogenic activity on chemical weathering rates via intersite LTER comparisons. The research is directed toward answering two questions: 1) what drives chemical weathering and 2) what are the links of chemical weathering to the ecosystem? The objectives are to: 1) initiate intersite comparisons that eventually include all LTER sites with surface and groundwater chemical fluxes, 2) utilize hydrologic and chemical data to calculate weathering rates, 3) test paradigms of weathering controls (T, P, etc.), and 4) link weathering to feedback mechanisms and ecology.To facilitate this research, an LTER-sponsored workshop was recently held with representatives from Luquillo, Konza, KBS, McMurdo, and North Temperate Lakes LTER sites. A position paper was developed to be given to the LTER PIs along with a questionnaire about each LTER site. Results from the questionnaire will be used to complete a data matrix started at the workshop on characterizing all LTERs. The data completed matrix will summarize the data available from and data needs of the various LTERs. A proposal will be submitted to NCEAS for workshop(s) to bring researchers from LTERs together to discuss weathering issues. Weathering rates will be developed for those sites that have already collected necessary data.A proposal for intersite work will be generated from these activities. The proposed research would provide for analysis of additional chemical parameters, including SiO2, as needed to develop complete chemical profiles at each site. An important aspect of this research is that it will provide a template for LTERs to collect a coordinated set of biogeochemical measurements that can be used for future intersite LTER comparisons.Return to Contents

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