Impacts of land uses on mercury retention in long-time cultivated soils, Brazilian Amazon

Comte Irina, Lucotte Marc, Davidson Robert, Reis de Carvalho Claudio, de Assis Oliveira Francisco, Rousseau Guillaume Xavier. 2013. Impacts of land uses on mercury retention in long-time cultivated soils, Brazilian Amazon. Water, Air and Soil Pollution, 224 (4):1515, 14 p.

https://doi.org/10.1007/s11270-013-1515-3

Article de revue ; Article de recherche ; Article de revue à facteur d'impact

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Quartile : Q2, Sujet : WATER RESOURCES / Quartile : Q2, Sujet : ENVIRONMENTAL SCIENCES / Quartile : Q3, Sujet : METEOROLOGY & ATMOSPHERIC SCIENCES

Résumé : Many studies have shown the relationship between fire clearing and mercury contamination of aquatic ecosystems in the Brazilian Amazon. This study aimed at quantifying mercury content in long-time cultivated soils and at assessing the potential of a fire-free alternative clearing technique on mercury retention for long-time cultivated soils compared to traditional slash-and-burn. This case study included five land uses: one crop plot and one pasture plot cleared using slash-and-burn, one crop plot and one pasture plot cleared using chop-and-mulch, and one 40-year-old forest as a control. Low mercury concentrations were recorded in the surface horizon (24.83 to 49.48 ng g−1, 0–5 cm depth). The long-time cultivation (repeated burnings) of these soils triggered large mercury losses in the surface horizon, highlighted by high enrichment factors from surface to deeper horizons. The predominant effect of repeated burnings before the experimental implementation did not let us to distinguish a positive effect of the chop-and-mulch clearing method on soil mercury retention for crops and pastures. Moreover, some processes related to the presence of the mulch may favor mercury retention (Hg volatilization decrease, cationic sites increase), while others may contribute to mercury losses (cationic competition and dislocation, mobilization by the dissolved organic matter).

Mots-clés Agrovoc : utilisation des terres, pollution du sol, mercure, système de culture, sol agricole, teneur en éléments minéraux, propriété physicochimique du sol, déboisement, culture sous couvert végétal, fertilité du sol, pratique culturale, jachère