CO2-driven cation leaching after tropical forest clearing.

The objective of this study was to investigate the role of dissolved CO2 (H2CO3*) as a mechanism of cation removal from surface soils under secondary land uses in the tropics. Soil leachate columns were prepared with 0?10 cm soils from mature and secondary forest, and managed pastures, and extracted with H2CO3* from deionized water equilibrated with 0%, 0.5%, 1%, and 10% CO2 (g). Extraction of soil cations slowed over time following an exponential form for the cumulative data. The rate of cation concentration decline varied as a function of CO2 concentration with the 10% solution resulting in a greater percent decline with extraction volume. Potassium removal from the exchange sites of all soils and for all solutions was nearly complete ranging from 85% to 97% while removals of Mg (31% to 71%) and Ca (12% to 42%) were lower. The asymptotic patterns of cation loss observed in this study suggest that H2CO3* acid-driven losses of cations may become self-limiting over time. Other stronger acids from atmospheric deposition or organic sources may serve to perpetuate cation removal, and re-forestation on these cleared lands would certainly re-distribute cations from soils to vegetation

Tree growth soil response to P fertilization in a 24-year-old tropical forest on an Oxisol.

Abstract ID: 82

Dissolved CO2 in small catchment streams of Eastern Amazonia.

Poster 525. Disponível também on-line

Stream water chemistry assessment in agriculture catchments in Eastern Amazonia.

Poster 568. Disponível também on-line

The chemistry of two streams draining kaolinitic soils.

Resumo 20.5

Streamwater Dissolved Organic Carbon and Total Dissolved Nitrogen: Effects of Timber Harvest in the Georgia Piedmont

Proceedings of the 2011 Georgia Water Resources Conference, April 11, 12, and 13, 2011, Athens, Georgia.A paired watershed experiment of silvicultural best management practices first initiated in 1973 and harvested in 1974/75 was harvested for a second time in 2004. During the current harvest, BMPs were updated to reflect current guidelines. Stream water yield and physical and chemical attributes were monitored for one year pre-harvest and one year post-harvest. Here we report results for dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) concentrations and fluxes. In the treatment watershed, no response to harvest in the discharge-concentration relationship was observed. Based on double mass curves, however, the yield of DOC and TDN increased in the treatment watershed as a result of increased stream water fluxes, although the increased mass of DOC or TDN loss was relatively small.Sponsored by: Georgia Environmental Protection Division U.S. Geological Survey, Georgia Water Science Center U.S. Department of Agriculture, Natural Resources Conservation Service Georgia Institute of Technology, Georgia Water Resources Institute The University of Georgia, Water Resources FacultyThis book was published by Warnell School of Forestry and Natural Resources, The University of Georgia, Athens, Georgia 30602-2152. The views and statements advanced in this publication are solely those of the authors and do not represent official views or policies of The University of Georgia, the U.S. Geological Survey, the Georgia Water Research Institute as authorized by the Water Research Institutes Authorization Act of 1990 (P.L. 101-307) or the other conference sponsors

Throughfall reduction: Impacts on solution nutrient fluxes.

Oral 399. Disponível também on-line