Mercury emissions from soil and litter during forest burning

Abstract

The mercury is a metal with an elevated toxic potential and, because of its high volatility, it is easily released to the atmosphere. The sources of this metal can be natural, anthropogenic or even from re-emissions. With the increase of anthropogenic activity, it has been observed increments on the amount of emitted or re-emitted mercury to the atmosphere. As biomass burnings accounts for an expressive part (8%)of the several sources of mercury to the atmosphere, the following project aims to study Hg emission from soils and vegetation (litter) during forest burning. The proposal consists on the accomplishment of burning experiments in the Amazon biome and in laboratory. As the initial hypotheses is that Hg emission happens in more severe burning conditions, it will be analyzed parameters that also have a relation with fire severity, such as the ratio between the concentration of the elements calcium and carbon present in the soil. Total Hg concentrations will be determined in soil and litter samples by using a direct mercury analyzer (DMA-80 TRI-CELL, Millestone). Soil samples collected in the experimental plot will be heated in a muffle furnace, varying the temperature and time of heating, in order to determine the influence of these parameters over the Hg emission rate. With this data set (mercury loss rates in function of temperature and relation calcium/carbon of the burnt soil), one intends to develop a mathematical modeling in order to estimate de Hg loss from a soil due to biomass burning. This study is part of the individual FAPESP project Impacto do desflorestamento sobre as emissões de Hg em floresta tropical da Região Amazônica, FAPESP Project 2010/19040-4, under the coordination of Prof. Dr. Anne Hélène Fostier. (AU)