Evaluation of the Siltation of River Taquari, Pantanal, Brazil, through 210Pb Geochronology of Floodplain Lake Sediments

Abstract

210Pb results, the mercury content was determined for two sediment cores, showing that despite a constant concentration, the flux of Hg has increased due to an increase in the mass sedimentation rate. This increase can be attributed to the expansion of agricultural activity in the upper Taquari River during the last 25 years.

A historical evaluation of anthropogenic impact in coastal ecosystems by geochemical signatures

“…Increasing Hg fluxes were also observed by Sanders et al, 39 2006. According to Godoy et al,6 2002, this tendency in Hg fluxes is an indication of increasing agricultural activity, which have been used in fertilizers that have Hg as a subproduct. Also, the decrease in the sediment grain-size towards the top of the core and an increase of organic matter concentration since the 1950's, are probably related to the construction of dams and the intensification of agricultural activity in the basin (Table 2).…”

“…A list of chemical properties of the radionuclide 210 Pb and of its parent in decay series of 238 U favors its use in the application in recent sediment cycles. 2 It has been successfully used in lakes [3][4][5][6][7] estuaries, [7][8][9][10][11][12] inner continental plataforms [13][14][15] and mangrove ecosystems. 15-19 210 Pb geochronologies are especially significant when confirmed by anthropogenic signatures in sediment profiles.…”

Changes in lead and mercury atmospheric deposition due to industrial emissions in Southeastern Brazil

“…32 However, this decrease has not been observed in similar studies in Amazon gold mining areas of Brazil, which consistently show increasing Hg concentrations toward the top of lake sediment profiles. 12,22,33,34 Surface Hg concentrations in the Itatiaia Mountains lake studied here are much lower than those measured in lake sediments in the Amazon. For example, in the Pantanal region, Central Brazil, 22,[34][35][36] Hg concentrations in surface sediments of remote lakes range from 60 to 120 ng g -1 .…”

“…12,22,33,34 Surface Hg concentrations in the Itatiaia Mountains lake studied here are much lower than those measured in lake sediments in the Amazon. For example, in the Pantanal region, Central Brazil, 22,[34][35][36] Hg concentrations in surface sediments of remote lakes range from 60 to 120 ng g -1 . In the Carajás mountains, 12,16 southeastern Amazon, ombrotrophic lakes, similar to those of the Itatiaia Mountains, present Hg concentrations in surface sediments ranging from 80 to 310 ng g -1 , while at the Alta Floresta mining area, 16,34 southern Amazon, concentrations ranged from 80 to 210 ng g -1 .…”

“…For example, in the Pantanal region, Central Brazil, 22,[34][35][36] Hg concentrations in surface sediments of remote lakes range from 60 to 120 ng g -1 . In the Carajás mountains, 12,16 southeastern Amazon, ombrotrophic lakes, similar to those of the Itatiaia Mountains, present Hg concentrations in surface sediments ranging from 80 to 310 ng g -1 , while at the Alta Floresta mining area, 16,34 southern Amazon, concentrations ranged from 80 to 210 ng g -1 . These results are in accordance to previous estimates 15,16,19,21 suggesting the larger importance of Amazon Hg emissions relatively to industrial emission 5 in Brazil, in the recent past.…”