controlling Hg loss from soils after forest conversion to
pastures are probably very similar, but may vary up to
one order of magnitude depending on Hg soil concen-
trations.
The results presented here show that deforestation
can be responsible for maintaining high Hg levels in the
Amazon environment, through a grasshopper effect of
Hg remobilization from the affected soils. The profiles
of Hg concentrations in the Candeias do Jamari soils
suggest stronger Hg leaching and more intensive
degassing to the atmosphere at the topsoil, after
conversion. Below the topsoil a gradual increa se in
concentrations and burdens occur, showing that the effect
of forest conversion to pasture affects only the surface
layers of the soil. As deforestation rates in the Amazon
region nearly doubled during the first years of the
present century, reaching about 23,000 km
2
, while gold
mining has significantly decreased, land use change is
today the most important mechanism of maintaining
high Hg content in most Amazonian environments.
Acknowledgement
This paper is part of the project ‘‘Biogeochemistry
of Mercury in Tropical Ecosystems’’ (BMT), financed
by the National Research Council of Brazil (CNPq)
through a PRONEX project, Proc. No. 66.2007/1998-0,
and the BIOMERCUR Y Program supported by the
German Ministry of Science and Technology. We
specially thank the students of the Environmental
Biogeochemistry Laboratory, Universidade Federal de
Rondoˆ nia, for the help with fieldwork.
References
Almeida, M.D., Lacerda, L.D., Temmer, C., Caba, A., Bastos, W.R.,
2004. Gaseous mercury emission fluxes over different soil use in the
Amazon. Book of Abstracts: Fourth International Symposium on
Environmental Geochemistry in Tropical Countries, Armac¸ a
˜
o dos
Buzios, pp. 34e36.
Aula, I., Braunschweiler, H., Laino, T., Malin, I., Porvari, P.,
Hatanaka, T., Lodenius, M., Juras, A., 1994. Levels of mercury
in the Tucurui reservoir and its surrounding area in Para, Brazil.
In: Watras, C.J., Huckabee, J. (Eds.), Mercury Pollution: Toward
Integration and Synthesis. Lewis Publ., pp. 21e40.
Aula, I., Braunschweiler, H., Malin, I., 1995. The watershed flux of
mercury examined with indicators in the Tucurui reservoir in Para,
Brazil. The Science of the Total Environment 175, 97e107.
Brabo, E.S., Angelica, R.S., Silva, A.P., Faial, K.R.F., Mascarenhas,
A.F.S., Santos, E.C.O., Jesus, I.M., Loureiro, E.C.B., 2003.
Assessment of mercury levels in soils, waters, bottom sediments
and fishes of Acre State in Brazilian Amazon. Water, Air and Soil
Pollution 147, 61e77.
Cordeiro, R.C., Turcq, B., Ribeiro, M.G., Lacerda, L.D.,
Capitaneo, J., da Silva, A.O., Sifeddine, A., Turcq, P.M., 2002.
Forest fire indicators and mercury deposition in an intense land use
change region in the Brazilian Amazon (Alta Floresta, MT). The
Science of the Total Environment 293, 247e256.
Feigl, B.J., Melillo, J., Cerri, C.C., 1995. Changes in the origin
and quality of soil organic-matter after pasture introduction in
Rondoˆ nia (Brazil). Plant and Soil 175, 21e29.
Fernandes, L.C., Guimara
˜
es, S.C.P., 2002. Atlas Geoambiental de
Rondoˆ nia. Rondoˆ nia, Governo do Estado de Rondoˆ nia.
Fostier, A.H., Forti, M.C., Guimaraes, J.R.D., Melfi, A.J., Boulet, R.,
Santo, C.M.E., Krug, F.J., 2000. Mercury fluxes in a natural
forested Amazonian catchment (Serra do Navio, Amapa State,
Brazil). The Science of the Total Environment 260, 201e211.
Friedli, H.R., Radke, L.F., Lu, J.Y., Banic, C.M., Leaitch, W.R.,
MacPherson, J.I., 2003. Mercury emissions from burning of
biomass from temperate North American forests: laboratory and
airborne measurements. Atmospheric Environment 37, 253e267.
Godoy, J.M., Padovani, C.R., Guimaraes, J.R.D., Pereira, J.C.A.,
Vieira, L.M., Carvalho, Z.L., Galdino, S., 2002. Evaluation of the
siltation of River Taquari, Pantanal, Brazil, through Pb-210
geochronology of floodplain lake sediments. Journal of the
Brazilian Chemical Society 13, 71e77.
Herpin, U., Cerri, C.C., Carvalho, M.C.S., Markert, B., Enzweiler, J.,
Friese, K., Breulmann, G., 2002. Biogeochemical dynamics
following land use change from forest to pasture in a humid
tropical area (Rondonia, Brazil): a multi-element approach by
means of XRF-spectroscopy. The Science of the Total Environ-
ment 286, 97e109.
Lacerda, L.D., 1995. Amazon mercury emissions. Nature 374, 20e21.
Lacerda, L.D., 2003. Updating global Hg emissions from small-scale
gold mining and assessing its environmental impacts. Environmental
Geology 43, 308e314.
Lacerda, L.D., Pfeiffer, W.C., Ott, A.T., Silveira, E.G., 1989. Mercury
contamination in the Madeira River, Amazon e Hg inputs to the
environment. Biotropica 21, 91e93.
Lacerda, L.D., Salomons, W., 1998. Mercury from Gold and Silver
Mining: A Chemical Time Bomb? Springer-Velag, Berlin.
Lacerda, L.D., de Souza, M., Ribeiro, M.G., 2004. The effects of land
use change on mercury distribution in soils of Alta Floresta,
Southern Amazon. Environmental Pollution 129, 247e255.
Lechler, P.J., Miller, J.M., Lacerda, L.D., Vinson, D., Bonzongo, J.-C.,
Lyons, W.B., Warwick, J.J., 2000. Elevated mercury concen-
trations in soils, sediments, water, and fish of the Madeira River
Table 3
Mercury release in mg m
ÿ2
and % by layer in slashed, silviculture and pasture soils relative to forest soils from Candeias do Jamari, Rondoˆ nia State,
Western Amazon
Depth (cm) Release (mg m
ÿ2
) % layer Release (mg m
ÿ2
) % by layer Release (mg m
ÿ2
) % layer
ForestePasture ForesteSlashed* ForesteSilviculture*
0e20 13.4 G 5.1 34.1 0.6 G 6.3 3.2 6.9 G 6.4 18.2
0e40 25.7 G 12.1 31.2 4.1 G 13.6 20.6 13.3 G 14.7 16.7
0e60 35.8 G 14.3 25.8 9.9 G 18.7 33.6 24.9 G 18.0 30.5
0e80 39.3 G 15.8 8.9 17.2 G 20.3 42.7 38.1 G 19.4 34.6
*No statistical difference (P ! 0.05).
185M.D. Almeida et al. / Environmental Pollution 137 (2005) 179e186