ABSTRACT
Artisanal gold (Au) mining is the activity with the highest consumption of mercury (Hg) and the main source of environmental contamination by this element, which is a recurring problem in the Amazon. In this study, contamination and risks caused by Hg to the environment and human health were evaluated in different forms of artisanal Au mining in the Brazilian Amazon. For this purpose, 25 samples of soils and tailings were collected in three types of artisanal mine and one native forest. The mineralogical analysis revealed that there is no occurrence of minerals constituted by Hg. However, the concentrations of Hg in underground mining tailings were very high and exceeded the prevention values established by Brazilian environmental legislation, indicating elevated risk to the ecosystem and human health. The enrichment factor indicated that underground mining tailings are enriched by Hg, submitted to cyanidation or not, suggesting anthropogenic source for the high concentrations of Hg. The geoaccumulation index and the contamination factor showed that the colluvial mining tailings are moderately contaminated, and the tailings from underground mining are highly to extremely contaminated, leading to very high risks to the environment and the health of children from the region. These results represent a great contribution to the Amazon, since they provide subsidies for the definition of policies to mitigate environmental contamination and associated risks.
Subject(s)
Mercury , Soil Pollutants , Child , Ecosystem , Environmental Monitoring , Gold , Humans , Mercury/analysis , Mining , Soil Pollutants/analysisABSTRACT
Cell walls are involved in manifold aspects of fungi maintenance. For several fungi, chitin synthesis, degradation and recycling are essential processes required for cell wall biogenesis; notably, the activity of ß-N-acetylglucosaminidases (NAGases) must be present for chitin utilization. For entomopathogenic fungi, such as Metarhizium anisopliae, chitin degradation is also used to breach the host cuticle during infection. In view of the putative role of NAGases as virulence factors, this study explored the transcriptional profile and evolution of putative GH20 NAGases (MaNAG1 and MaNAG2) and GH3 NAGases (MaNAG3 and MaNAG4) identified in M. anisopliae. While MaNAG2 orthologs are conserved in several ascomycetes, MaNAG1 clusters only with Aspergilllus sp. and entomopathogenic fungal species. By contrast, MaNAG3 and MaNAG4 were phylogenetically related with bacterial GH3 NAGases. The transcriptional profiles of M. anisopliae NAGase genes were evaluated in seven culture conditions showing no common regulatory patterns, suggesting that these enzymes may have specific roles during the Metarhizium life cycle. Moreover, the expression of MaNAG3 and MaNAG4 regulated by chitinous substrates is the first evidence of the involvement of putative GH3 NAGases in physiological cell processes in entomopathogens, indicating their potential influence on cell differentiation during the M. anisopliae life cycle.
ABSTRACT
RESUMO O presente trabalho consistiu em avaliar as concentrações de nutrientes e metais pesados nos sedimentos do fundo do lago Água Preta, localizado na Região Metropolitana de Belém, Estado do Pará. As concentrações de metais pesados foram obtidas por espectrometria de emissão por plasma acoplado a espectrometria de massas (ICP-MS). Os metais que apresentaram maior concentração foram o cromo (245 mg.Kg-1) e o níquel (97 mg.Kg-1), os quais estiveram acima do índice que determina o nível de efeito provável (Probable Effect Level - PEL). O trabalho evidenciou o reflexo das pressões antrópicas que o lago Água Preta vem sofrendo ao longo dos anos, mostrando que os sedimentos de fundo se encontram impactados por metais pesados, altas cargas de matéria orgânica e nutrientes.
ABSTRACT The present study evaluated the concentrations of nutrients and heavy metals in bottom sediments of Água Preta lake, located in the metropolitan region of Belém, Pará state, Brazil. Concentrations of heavy metals were obtained by emission spectrometry with inductively coupled plasma mass spectrometry (ICP-MS). Metals that showed high concentrations were chromium (245 mg.Kg-1) and nickel (97 mg.Kg-1), both above Propable Effect Level (PEL) index. The work revealed the reflection of the anthropogenic pressures that Água Preta lake has suffered over the years, showing that the bottom sediments are impacted by heavy metals, high loads of organic matter and nutrients.
