The role of sorption in retention of dissolved organic carbon in soils of the lowland Amazon basin
Sonya
M
Remington, University of Washington, School of Oceanography, sunny9@u.washington.edu
Vania
Neu, CENA-Universidade de Sao Paulo, bioneu@inpa.gov.br
Jeffrey
E.
Richey, University of Washington, School of Oceanography, jrichey@u.washington.edu
Erin
Ellis, University of Washington, elliserin@yahoo.com
(Presenting)
Ecosystem processes in river corridors represent a significant pathway for the export of carbon fixed on land in the humid tropics at a globally significant level. The quantity of dissolved CO2 in surface waters of tropical river systems is the product of a long sequence of complex biological, hydrological and geochemical processes. Sorption is an important geochemical process that removes dissolved organic carbon (DOC) from water percolating through soils, which may eventually flow into the river channel (via groundwater and subsurface flow) where it may be respired to CO2. Soil properties, such as texture, Fe- and Al-oxide content, mineral surface area and organic carbon content, are known to affect the concentration of DOC in soil pore water and, therefore, the quantity of DOC transported to river channels. These soil properties vary with soil type. We collected samples from two depths of three different soil types typically found in the lowland Amazon Basin for use in equilibrium and kinetic laboratory "batch" experiments. Batch experiment results showed that the soils of the plateau and slope sorbed ~60% of new DOC input, while valley soils sorbed ~30%. Most DOC was sorbed within the first four hours of the 24 hour batch experiments. The role of respiration in DOC loss from solution during the experiments appeared to be small relative to loss by sorption. Understanding and quantifying DOC lost to sorption as a function of soil properties is an important step in understanding the export of carbon fixed on land and transported to rivers.
Submetido por Sonya Marie Remington em 24-MAR-2004
Tema Científico do LBA: CD (Armazenamento e Trocas de Carbono)