An agroforestry system (AFS) describes the conjoint use of land for agricultural andforestry purposes. An AFS plays a strategic role in the mitigation of carbon dioxide(CO2) emissions, and stands as an alternative in land use that reduces mercury (Hg)remobilization in cultivated soils. This study evaluated the spatial variability of Hgconcentrations as indicators of environment changes and soil quality in different landcover and use systems in a rural settlement in southern Amazon, Brazil. Themethodological procedures were carried out as steps: the experimental units weredefined, physical and chemical characteristics of soil samples were analyzed, anddata were evaluated using conventional and spatial statistics. The AFS included hadbeen established 10 years before or more, and had high Hg retention capacity ,compared with Hg levels in soils on migratory agriculture or that are not fallowed .Therefore, due to low AFS improve soil quality due to the low intensity of harrowing,increasing retention of gaseous and particulate Hg in the soil.
O presente estudo teve o objetivo de avaliar as mudanças no uso da terra e seus efeitos na qualidade da água na microbacia do rio Preto - RO. Esta foi escolhida por ser uma área de projetos de assentamento para colonos, o que viabilizou o processo de ocupação do estado de Rondônia. A metodologia foi dividida em três etapas: preparação da base cartográfica e processamento digital de imagens de satélite, atividade de campo com aplicação de formulário sobre o uso da terra e coleta de amostras de água, e integração das informações através de Sistema de Informação Geográfica - SIG. Na área sobre influência da agricultura cafeeira a concentração de OD foi 1,61 mg/l, a temperatura de 27,5º C, pH entre 4,4 e 4,7 e média de condutividade 15,8 ïS25/cm. Foi constatado mudança no uso da terra, que está relacionada ao desenvolvimento econômico recente e histórico de colonização. Como consequência trechos de rios apresentam padrão de qualidade de água inferior ao recomendado pela legislação CONAMA Nº 357/2005.
The extraction of gold in the Amazon, since 1970, has grown fast from a politic that was resulted in the creation of gold extraction reserves in this region. In the Madeira River the gold exploration is noticeable because of the deposition of mercury in the environment. This metal is toxic and it resists to degradation process, transforming itself chemically, till it gets to its organic form, known as very toxic. Its extensive usage in the gold recover has caused impacts to the environment and consequently to the population, according to studies already done. This study has as its goal to value the pollution by Hg in soils and the variation according to soil fractions. The soils were collected by profiles in 10 areas in the Madeira River. The determination of organic matter was done, according (BRASIL, 1999).To Hg determination it was selected the fraction <200 mesh (<74 m), analyzed by atomic absorption spectrophotometer coupled vapor cold generation (Bastos et. al, 1998). Soils of the kind Latosols and hydromorphic were identified. The Latosols presented from 288 to 641 g.Kg -1 of clay and from 266 to 111 g.Kg -1 of thin send, from the horizon A 1 (superficial) to B 2 (sub-superficial). The increase of values of clay makes the function of organic matter in the superficial horizon better (from 20,2 to 19.0 %). The Hg concentration in these horizons varies from 25,5 to 641,4 g.Kg -1 in the superficial horizon. The hydromorphic, especially, the Fluvic Neosols, present thin area, 396 to 57 g.Kg -1 and clay from 254 to 654 g.Kg -1 from A 1 to A 2 . The horizon A 2 presents 467 g.Kg -1 of silt, 13,6 % of OM and 147,31 gHg.Kg -1 .Among the soils groups of the studied area, it is noticed more Hg concentration with the increase of values of silt and clay, that consequently presents more tenor of OM, and that subsidizes the organic mercury forming.
This study aims at analyzing the deforestation evolution correlated to the proposal of a territorial planning implanted by Rondônia Social-Economical and Ecological Zoning -SEEZ -decree number 4.297 signed in July 2002), regulated in 2002. In order to determine the indicators of degradation (deforestation), we opted for the analysis of maps of deforestation
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