ABSTRACT
We present results of mercury (Hg) in surface waters and soils and an analysis of satellite imagery from the Tapajós River basin, Brazilian Amazon, and the Reserva Garimpeira do Tapajós, the legal gold mining district of the basin. Hg bound to suspended sediment was roughly 600 and 200 times the concentration of dissolved Hg per litre of water, in impacted and pristine areas, respectively. Suspended sediments thus represent the major pathway of river-borne Hg. Median concentrations of Hg in suspended load from both impacted and pristine waters were 134 ppb, and 80% of samples were below 300ppb-in the range of naturally occurring surficial materials in the tropics. Regionally, riverine Hg fluxes were proportional to the concentration of total suspended solids. This shows that the dominant source of Hg is the sediment itself rather than anthropogenic mercury discharge from the small-scale mines. To independently test this conclusion, a mass balance was performed. A conservative calculation of the annual export of mercury (Hg) from the Creporí River (a minimum) was 1.6 tonnes for the year 1998-it could be significantly larger. This amount of Hg is difficult to account for by anthropogenic discharge alone, confirming that enhanced physical erosion caused by sluicing and dredging operations is the dominant source of Hg. We therefore conclude that gold mining operations are primarily responsible for elevated Hg concentrations. The dominant source of contamination is not, however, the loss of Hg in the gold amalgamation process. Rather, the disturbance and mobilization of large quantities of Hg-rich sediment and floodplain soil into the water column during mining operations is the source of contamination. These findings shift the focus of remediation and prevention efforts away from Hg control toward soil and sediment erosion control. The minimization or elimination of Hg losses in the mining process remains important for the health of local peoples and environments, but keeping basin soils and sediments in place would be a much more effective means of minimizing Hg fluxes to the region's rivers. To gain a spatial and historical perspective on the source and extent of emissions, satellite imagery was used. We were able to reconstruct historical mining activity, locate impacted areas, and estimate historical Hg fluxes with the imagery. To do so, the spectral characteristics of satellite images were calibrated to the concentration of suspended sediment in the rivers, which, in turn, is proportional to the Hg concentration. This analysis shows that mining-induced sediment plumes have been a dominant source of sediment to the Tapajós River system for decades. As well, the intensity and location of these emissions has varied through time. For example, sediment discharge from the Creporí River was greater in 1985 than in 1998; and the tributaries on the west bank of the Tapajós were actively being mined in 1985 but had been abandoned in 1998. This type of information should greatly assist in understanding original and ongoing sources of emissions, and in managing prevention and remediation efforts.
Subject(s)
Geologic Sediments/analysis , Geologic Sediments/chemistry , Mercury/analysis , Rivers/chemistry , Satellite Communications , Soil/analysis , Brazil , Mercury/chemistry , Time FactorsABSTRACT
Muiraquitãs arc frogshape stone artifacts made mainly in greenstones like jade, used by peoples of Tapajó/Santarém and Conduri tradition/culture from Lower Amazon region, which were extinguished by european colonizators. They used as amulets, symbol of power and as trade materials. The majority of studiers believe that the greenstone jade come from Asia and reinforce the peopling of South America from Asia through North America. Mineralogical and chemical analyses over ten pieces of muiraquitãs from Museu Paraense Emílio Goeldi (MPEG), Museu de Arqueologia e Etnografia from Universidade de São Paulo and from prof. Amarilis Tupiassu show that they are made of tremolite for MPEG and prof. Amarilis and acti-nolite, talc and pyrphyllite for MAE. Tremolite and actinolite are the most common minerals of the nephritic jade, which is not too rare. The microchemical analysis aggree with the mincralogical determinations and show that the jade from MAE contain sulphate and ferrous iron and differ from the jade of muiraquitã of MPEG. Both jade can not be correlated with the jade of Baytinga (Amargosa-BA). Tremolite and actinolite are common minerals in proterozoic formations of Amazon region and dismitified the asking for an asian provenience of raw material of muiraquitãs as well as the interpretation of a peopling move from Asia to South America trough North America.
Os muiraquitãs são artefatos líticos com formas batraquianas confeccionados principalmente em pedra verde, tipo jade, utilizados pelos povos Tapajó/Santarém e Conduri do Baixo Amazonas, dizimados pelos colonizadores europeus. Eram utilizados como amuletos e como símbolo de poder e ainda como objeto de troca. Supunha-se que o jade viera da Ásia. Estudos mineralógicos e químicos em dez peças do Museu Paraense Emílio Goeldi (MPEG), do Museu de Arqueologia e Etnografia (MAE) da Universidade de São Paulo e profa. Amarilis Tupiassu mostram que os muiraquitãs do MPEG e da profa. Amarilis são confeccionados em tremolita e os do MAE em actinolita, talco e pirofdita. Tremolita e actinolita são os minerais mais comuns de jade nefrítico, que não é assim tão raro. As microanálises químicas confirmam as determinações mineralógicas e ainda mostram que o jade do MAE contém sulfato e ferro ferroso. Tanto o jade do MPEG como do MAE diverge daquele de Baytinga (Amargosa-BA). Rochas ricas cm tremolita e actinolita são muito comuns no Proterozóico da Amazônia, encontrados tanto ao norte como ao sul da bacia, próximo na região do Baixo Amazonas, sendo desnecessário invocar uma fonte asiática para o jade dos muiraquitãs. Portanto se tornam vulneráveis às interpretações etnográficas e antropológicas com base em área asiática como fonte para a matéria-prima destes artefatos.
ABSTRACT
The first indirect written informations about the muiraquitãs, are related to Orellana, who traveled the Amazon river for the first time downstream in 1542 and mentioned presence of the Amazonas Indians, living without husbands and act as brave fighters. De la Condamine during his travel in 1735 along the Amazonas discribed frogshape amulet made of greenstone like jade used by Amazonas. Spix and Martius written about pierres divines, and used the name Muraquêitã for frogshape pendant made of motherpearl. However older writtens of Maurício Heriarte used therms close to muiraquitã: baraquitãs, buraquitãs, puúraquitan, uuraquitan, mueraquitan. Finally Barboza Rodrigues at 1875 brought the name muyrakytã to well acept therminology which was reinforced by Francisco Barata in 1954 as muiraquitã. Barata defines as a frogshape artifact sculptured in greenstones, jade. Muiraquitã is of tupi origin meaning using frogshape pendant. They were used by Indians of Tapajó/Santarém and Conduri Tradition which lived at the Lower Amazon region until the first contacts with the European colonizators. To make the muiraquitãs, artifact of high finnished carving, one presumes that the Indians used ingenious processes, meanwhile the most important was patience and ability. The most important centre of frogshape artifact carving was the Lower Amazon. Although supposed to be Asia, the source of the raw material must have been the Amazonia. The muiraquitã were used as amulet and symbol of power between the chiefdoms in the Amazon region during its time. About them there arc several legends and myths always connecting with the Amazonas fighters of Orellana.
Aparentemente os primeiros dados documentados sobre a história dos muiraquitãs, ainda que inferidos, surgem com Orellana, tido como o primeiro explorador a navegar o rio Amazonas rio baixo, ainda em 1542, quando teria combatido com índias guerreiras valentes, sem maridos, as quais denominou de Amazonas. Posteriormente De la Condamine em sua viagem ao longo deste rio, em 1735, descreve amuletos batraquianos em pedras verdes semelhantes a jade. Spix e Martius escrevem sobre pierres divines como pingente batraquiano em madrepérola e com nome de muraquêitã. Antigos escritos de Maurício Heriarte de 1662 descrevem amuleto com termos similares: baraquitãs, buraquitãs, puúraquitan, uuraquitan e mueraquitan. Finalmente Barboza Rodrigues em 1875 emprega o termo muyrakytã modificado por Barata em 1954 para muiraquitã, que entende como artefatos em forma de sapo confeccionados em pedra verde, com dois furos laterais. Teriam sido usados pelos povos Tapajó/Santarem e Conduri, que habitavam o Baixo Amazonas até a chegada do colonizador europeu, que os dizimou. Para elaborar os muiraquitãs acredita-se que esses povos utilizavam instrumentos engenhosos, mas principalmente muita paciência e habilidade. Os estudos mais recentes mostram que o maior centro produtor estava na região, da mesma forma como a fonte da matéria-prima e não na Asia como suposto pelos historiadores. Eram utilizados como amuletos, símbolos de poder, e ainda como material para compra e troca de objetos valiosos. Sobre eles há muitas lendas e mitos sempre envolvidos com as índias Amazonas, extintas ou lendárias.
