Attenuation of acid mine drainage (AMD) metals originating from abandoned mines and waste rock dumps is investigated in this thesis at Slättberg in central Sweden, where acid mine leachate has been discharging for over 70 years into the receiving wetland stream and mire. Risk assessment of AMD and related polluted lands requires a holistic approach that is able to study the complexity of pollution emissions and impacted landscapes. In this thesis a link between geochemical contaminant fate modelling and landscape analysis is presented for AMD risk assessment. A simple geochemical landscape analysis tool is developed to analyse and model geochemical abundances, geochemical gradients, geochemical flow patterns and geochemical barriers in the studied stream and mire sediments. Sampling locations at geochemical barriers are identified using landscape geochemical and GIS methods. A sequential chemical extraction procedure is used to investigate fractions which are expected to act as potential sinks of the six studied metals (Cu, Fe, Mn, Ni, Pb and Zn) in the sediments. For data modelling robust statistical methods of Exploratory Data Analysis are used to treat small sample sizes with multimodal character and outlying values. The spatial variability of metal retention in the sediments is studied by multivariate data analysis methods. Results show that the developed simple geochemical landscape analysis method can be used efficiently for the risk assessment of toxic mine contaminants in the complex receiving wetland landscape. It is suggested by the analysis that the oxidising geochemical barrier in the stream sediments can be sufficiently characterised by the distribution of Fe fractions. At the AMD discharge location metal sulphide formation and organic matter adsorption control metal retention in the mire. Mires are very sensitive to changes in hydrological conditions and drying of the sediments leads to erosion and hence the release of adsorbed metals to the environment.

Thesis (Ph. D.)--University of Western Sydney, 2003. / "A thesis submitted to the School of Engineering and Industrial Design, University of Western Sydney, in partial fulfilment of the requirements of the degree of Doctor of Philosophy." Includes bibliographical references and appendices.

Made available in DSpace on 2015-03-26T13:53:13Z (GMT). No. of bitstreams: 1 texto completo.pdf: 3214243 bytes, checksum: 9594a0e8832b60dfa2edda6f97dc2552 (MD5) Previous issue date: 2010-02-12 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Located on Admiralty Bay, King George Island, Keller Peninsula has an area of approximately six square kilometers and there are records of presence of basalt, volcanic tuff, basalt-andesite and andesite in the geologic base. The latter two show veins of sulfides of late mineralizationhave high levels of sulfides, which shows a natural potential generation of acid rock drainage. In order to analyze the presence and influence of the acid rock drainage process on the availability of metals in water discharged into the sea in the Keller Peninsula, water samples at various points in watercourse to the sea, were collected during the months of February and March 2009, on different lithologies and drainage basin. Sediment samples were also collected from the bottom of the waterways. The water samples were acidified and filtered on cellulose ester membrane of porosity 0.45 μm. Were determined the following elements by Spectrophotometry of Optical Emission in Induzed Plasma: Al, As, B, Cd, Co, Cr, Cu, Fe, K, Mn, Mo, Ni, Pb, S, Ti, V, Zn. The chemical conditions of water samples showed pH values close to neutrality even in close proximity of sulfide deposits and in some places, even on these. It was observed that the drainage basin are divided between: a) basins strongly affected by sulfides oxidation; b) basins affected by sulfides oxidation and c) basins not affected by sulfides oxidation. It was also found that concentrations of ions in solution were always higher in the watershed affected by sulfides indicating a breakthrough in the chemical weathering process in these areas. Four sulfide deposits not previously reported in geological manuscripts were recorded and it was observed that these are always associated with geological faults. Among the secondary minerals dominated the species of the jarosite, as well as the Schwertmannite and other low crystallinity minerals. The presence of low crystallinity minerals, with high adsorption capacity minerals, founded too in beaches and marine terraces, suggests that a large portion of the concentration recorded in the waterways is not actually available in the pH environmental conditions recorded at the time of samples collection. Moreover, although the secondary minerals observed are of high instability it was not observed more crystalline forms of oxides and Iron oxyhydroxides. Due to the chemical conditions of pH of the samples recorded at the time of collection it is suggested that the term acid rock drainage is not suitable for this case. The process that occurs in the Keller Peninsula is the occasional generation of acidic waters influenced by the dynamics oxidation of sulfides, its soil gradation and mineral species, and against neutralization by melting and consumption of acidity by carbonates and silicates. / Localizada na Baía do Almirantado, Ilha Rei George, a Península Keller possui uma área de aproximadamente seis quilômetros quadrados e registra a presença de basaltos, tufos vulcânicos, basaltos-andesítos e andesitos em sua base geológica. As duas últimas apresentam veios de sulfetos de mineralização tardia, revelando um potencial natural de geração da drenagem ácida. Com o objetivo de analisar a presença e influência do processo de drenagem ácida sobre a disponibilidade de metais nas águas lançadas ao mar na Península Keller, foram coletadas, durante os meses de fevereiro e março de 2009, amostras de água em diversos pontos dos cursos d água até o mar, sobre diferentes litologias e bacias de contribuição. Também foram coletas amostras do sedimento de corrente dos canais. As amostras de água foram acidificadas e filtradas em membrana de ésteres celulose de porosidade 0,45 μm. Foram dosados os seguintes elementos por Espectofotômetria de Emissão Ótica em Plasma Induzido: Al, As, B, Cd, Co, Cr, Cu, Fe, K, S, Mn, Mo, Ni, Pb, S, Ti, V, Zn. Cloreto, brometo, fluoreto, e sulfato foram analisados em Cromatógrafo de Troca Iônica. As condições químicas das amostras de água revelaram valores de pH próximos da neutralidade mesmo em locais muito próximos dos depósitos sulfetados e, em alguns locais, mesmo sobre esses. Registrou-se que as bacias de contribuição dividem-se entre: a) fortemente afetadas pela oxidação de sulfetos; b) moderadamente afetadas pela oxidação de sulfetos, e; c) não afetadas pela oxidação de sulfetos. As concentrações dos íons em solução foram sempre maiores nas bacias afetadas por sulfetos, indicando um avanço do processo de intemperismo químico nessas áreas. Foram observados quatro depósitos de sulfetos não relatados anteriormente em registros geológicos da Península Keller. Os depósitos encontram-se sempre associados às falhas geológicas. Dentre os minerais secundários presentes, dominaram as espécies da família da jarosita, com destaque para a Schwertmanita, e outros minerais de baixa cristalinidade. A presença de minerais de baixa cristalinidade, com elevada capacidade de adsorção, encontrados também nas praias e terraços marinhos, sugere que grande porção da concentração iônica nas águas acidificadas não está efetivamente disponível nas condições ambientais de pH registradas em campo. Ademais, ainda que os minerais secundários constatados sejam de elevada instabilidade, não foram observados formas mais cristalinas de óxidos e óxihidróxidos de Ferro. Devido às condições químicas de pH encontradas em campo sugere-se que o termo drenagem ácida não é adequado a este estudo de caso. O processo que ocorre na Península Keller é a geração pontual de águas ácidas, influenciadas pela dinâmica de oxidação de sulfetos, sua granulometria e espécies minerais associados, e contra a neutralização por silicatos e carbonatos, bem como, diluição da acidez pelo degelo.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A bacia hidrográfica do rio São Domingos constitui uma das sub-bacias do rio Muriaé pertencente ao sistema Paraíba do Sul e, tem seus limites coincidentes com os limites do município de São José de Ubá, sendo este o segundo maior produtor de tomate do estado do Rio de Janeiro, com sua principal fonte econômica baseada na agropecuária. Este tipo de atividade resulta em utilização de produtos químicos nas lavouras e juntamente a ocupação inadequada resulta em modificação das paisagens e da mata nativa, resultando em diversos tipos de impactos no ambiente. Neste estudo foram abordados os impactos relacionados a concentração de metais e sua proveniência através das assinaturas isotópicas Pb/Pb, utilizando para tal o procedimento analítico de lixiviação dos sedimentos de corrente e abertura total de rochas para a obtenção de razões isotópicas e concentrações de metais por ICP-MS. Os resultados mostraram que as contribuições nos sedimentos de corrente se dão a partir de cinco fontes compreendidos no intervalo de assinatura isotópica 206Pb/207Pb 1,1229 e 1,1949, representadas em intervalos bem definidos. Por correlação com as respectivas concentrações se observa que, preferencialmente, existe maior influência das rochas do embasamento, seguido de atividade antrópicas como a urbanização e disposição de lixo doméstico. As maiores concentrações estão associadas ao cobre, chumbo, estrôncio, níquel e zinco. Contudo todas as concentrações de metais obtidas se encontram abaixo da legislação vigente. Desta forma a contaminação antrópica é limitada a regiões de maior densidade populacional e as influências naturais predominam na área da bacia. / The São Domingos river basin is a sub-basin of the river Muriaé belonging to the Paraíba do Sul system, than his boundary are coincide with the limits of São Jose de Ubá County the second largest tomato producer in the Rio de Janeiro state, with its main financial activity based on the agricultural economy. This kind of activity results in a use of chemicals on crops and modification of the landscape and native vegetation, resulting in various types of environmental impacts. In this paper was study the impacts related to concentration of metals and their provenance by Pb/Pb isotopic signatures, using to analyze procedure the rocks sample digest and leaching of stream sediments to obtained metal concentration and isotope ratios by ICP-MS. The results showed that concentrations on stream sediments have five different sources identifiable from five intervals isotopic signature 206Pb/207Pb 1.1229 to 1.1949 clearly defined. By this correlation with owner respective concentration it is observed than, preferentially, the basement rocks are the main influence in the basin stream and in second place come the mixtures of products of activities anthropogenic, mainly urbanization and sewage disposal. The biggest metals concentrations are cupper, lead, strontium, nickel and zinc. However all of metals concentrations are below actual legislation. That way the anthropic contamination it is located in areas with more intensity occupation and the natural sources predomination on the basin.

Surface and groundwaters in contact with mining-exposed pyritic materials have the capacity to generate acid mine drainage (AMD), an acidic, sulfate-rich, metals-laden effluent. The Davis Mine located in northwestern Massachusetts offers a model site to study the processes of natural attenuation of acid mine drainage. These include physico-chemical processes such as dilution and sorption, geochemical processes such as aluminosilicate weathering and biological processes such as transformation and cycling of sulfate, iron and acidity by bacterial metabolism. A focus of recent research undertaken at the site has been characterizing the presence and activity of these bacteria with an aim to stimulate their capacity to attenuate the severity of acidic conditions. To further this investigation, a pilot-scale treatment system was installed, composed of a modified permeable reactive barrier containing organic carbon and limestone. Down-gradient groundwater was sampled over a sixteen-month period for concentrations of dissolved metals, major cations and sulfate, along with pH and redox measurements. The results showed a decrease in dissolved metals, a possible increase in calcium and decrease in sulfate, and measurable increase in pH and corresponding decrease in oxidation-reduction potential. Major decreases in dissolved iron and aluminum were observed, a change which is not entirely consistent with metals removal by combination with biogenic sulfide alone. The additional influence of hydrolysis was proposed and the anticipated action of this alternate process found to bear resemblance to the observed changes. Groundwater composition from the experimental period was compared to previous measurements and significant changes described in pH, iron, aluminum, copper and zinc and to a lesser extent in calcium and sulfate. Comparisons were also made with concurrent surface water compositions and findings of analogous studies. Conclusions that can be drawn include: the pH and redox environment into which a treatment system is placed can greatly influence the reactions which take place, side-reactions which occur in reducing and alkalinity-generating amendments may also have an attenuating effect, and variable processes influence groundwater composition in these biogeochemically complex environments.

Relationships between trace metals and nanoparticles were investigated using analytical transmission electron microscopy (aTEM) and asymmetric flow field flow fractionation (aFlFFF) coupled to both multi-angle laser light scattering (MALLS) and high resolution-inductively coupled plasma mass spectroscopy (HR-ICPMS). Riverbed sediment samples were taken from the Clark Fork River in Montana, USA where a large-scale dam removal project has released reservoir sediment contaminated with toxic trace metals (namely Pb, Zn, Cu and As) which accumulated from one and a half centuries of mining activities upstream. An aqueous extraction method was used to attempt to separate the nanoparticles from the bulk sediment. After analysis of initial results, it was found that low density clays were being selected for in this process and made up a major portion of the particles within the extracts. However, it was also realized that the metals of interest were associated almost exclusively with nano-sized Fe and Ti oxides. In order to more fully examine these relationships, a density separation method, using sodium polytungstate (2.8g/cm3), was developed to separate these higher density oxides from the lower density clays. The heavy fraction was then subjected to an aqueous extraction routine to extract the nanoparticulate fraction. FFF results indicated a smaller size distribution and more ideal fractionation with this method. The aFlFFF-HR-ICPMS profiles for Fe and Ti also matched strongly with the data for the trace metals. The majority of particles analyzed with the TEM were nano-sized Fe and Ti oxides (most commonly goethite, ferrihydrite and brookite), which typically had trace metals associated with them. In many cases, it was aggregates of these nano oxides that were found hosting trace metals. Nanoparticles and aggregates are known to behave differently than their bulk mineral phases or constituent particles, respectively. Nanoparticles are also capable of extended transport in the environment. For these reasons, it is important that their associations with toxic trace metals be extensively evaluated, as they will affect the bioavailability and toxicity of these metals with implications for any type of contaminant sediment relocation, dam removal or metal contaminated site. / Ph. D.

No description available.

PUMPS mimics natural geothermal vents as a conceptual model designed for the remediation of acid mine water (AMW) in voids of abandoned gold mines of the Witwatersrand Basin in South Africa. In this system, a reaction chamber containing Desulfotomaculum kuznetsovii sulfate reducing bacteria will be set at the bottom of a 3-4 km deep mine that will be flooded. A geothermal system with at least one (1) doublet will be drilled from the bottom of the mine to the depth of 8km, where the temperatures are sufficient for geothermal energy harvesting. AMW, used as a geothermal fluid, will be pumped down the injection well and circulate through hot rock. The hot water is then used to generate electricity and then channelled into the reaction chamber to undergo bio-remediation. Following treatment, the water flows back into the mine voids where it will improve the quality of untreated AMW through dilution. Eventually, the mine will be flooded with clean water that can be stored underground and/or pumped up to surface for social and ecosystem services. Following an introduction and proof of concept for the PUMPS, the research builds further on the technical and economic evaluation of the PUMPS in order to assert its viability and sustainability. The technical viability includes testing the ability for Desulfotomaculum kuznetsovii to survive in high pressure condition; quantifying the amount of energy that can be drawn from the geothermal reservoir; determining the placement and scheme of the geothermal wells; and, finally, developing a robust economic model of the system. Experiments show that Desulfotomaculum Kuznetsovii can tolerate high pressure conditions in of at least 100bar at their ideal sulfate reducing temperature of 63°C. Geochemical modelling shows that AMW can be used effectively as a geothermal fluid for PUMPS. To achieve highest efficiency and minimal fluid loss, the geothermal wells should be placed along the SSE-NNW direction, based on the known stress field across the Witwatersrand Basin. With a flow rate of 30l/s the energy drawn from the geothermal reservoir is sufficient to drive PUMPS and the surplus energy is determined by the volume of AMW treated per day. All results indicate that the PUMPS is technically and economically viable. The economic model shows that the value and viability of the PUMPS is best reflected with a comprehensive inclusion of potential revenue (for example from chemical solution mining of deep seated gold) and financial/environmental incentives.

L’accroissement de l’urbanisation et le développement industriel modifient la composition des géosphères de la Terre, en augmentant le nombre de problèmes géoécologiques et en affectant négativement la santé humaine. Actuellement, plus d'attention est accordée à la surveillance de l'état des composants de l’environnement naturel urbain. En Russie, les méthodes biogéochimiques (par ex., l'application de feuilles des arbres comme un récepteur naturel de la pollution) sont largement utilisées pour caractériser les problèmes géoécologiques des territoires dans des conditions d’intensité d’activités industrielles. Dans les pays occidentaux, les méthodes permettant d'estimer l'impact des facteurs ambiants sur la géosphère et la santé humaine sont répandues, parmi lesquelles l'évaluation des impacts du cycle de vie (ÉICV). Cependant, ces méthodes ne sont toujours pas appliquées en combinaison. L’utilisation d’indicateurs efficaces reflétant l'intensité de l'impact anthropique sur les écosystèmes; d’une cartographie de la distribution des polluants, ainsi que l'utilisation a posteriori de ces résultats dans l'évaluation des impacts sur l'environnement et la prédiction de leurs effets négatifs des entreprises industrielles (toxicité humaine et l'écotoxicité) sont pertinents pour l'évaluation complète des écosystèmes urbains. Cette méthode intégrée a été proposée et mise en œuvre sur le territoire d’Ust-Kamenogorsk, l'une des villes ayant subie des transformations technogéniques significatives au Kazakhstan avec un ensemble spécifique d’entreprises / With widespread urbanization and industrial development, the composition of the Earth's geosphere shells has changed, increasing the number of geoecological problems of territories and negatively affecting human health. Currently, more attention is being paid to monitoring the state of the components of urban natural environments. In Russia, biogeochemical methods (e.g. applying tree leaves as a kind of natural receptor of pollution) are widely used to characterize the geoecological problems of the territories under the pressure of intensive industrial activities. In Western countries, methods allowing us to estimate the impact of ambient factors on ecosystems and human health have become widespread; life cycle impact assessment is among them. However, these methods still have not been applied in combination. Therefore, the implementation of a comprehensive assessment of urban ecosystems using indicators reflecting the intensity of anthropogenic impact on ecosystems, following mapping of pollutant distributions, as well as the subsequent use of the results in the evaluation of the industrial enterprises' impact on the environment and in the prediction of the negative effects of pollution (human toxicity and ecotoxicity) are relevant. Such integrated method combining two methodologies was suggested and implemented in the territory of Ust-Kamenogorsk city, one of the significantly technogenic transformed cities in Kazakhstan with a specific set of enterprises

Made available in DSpace on 2015-02-24T19:48:45Z (GMT). No. of bitstreams: 1 AdrianaBG_capa_ate_secao5.pdf: 3230514 bytes, checksum: e499db1cdb9c0ab6b161220ff77e224a (MD5) Previous issue date: 2006-10-27 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The Curimata? estuary is located in the oriental coast of Rio Grande do Norte State in Brazil. Its importance resides in the fact that this region possesses one of the last portions of preserved mangrove in the Rio Grande do Norte State. Nevertheless, it has been severely affected by many anthropogenic activities, as sugarcane monoculture and shrimp farming. Former works demonstrated that an accumulation of heavy metals is occurring in oysters in this estuary, and perhaps it could be explained by the input of metals in this ecosystem deriving from the shrimp farming. To better understanding the origin of these metals, bottom sediment samples, cores and suspended particulate matter were collected for a characterization of metal concentrations (Al, Ba, Cd, Cu, Cr, Fe, Mn, Ni, Pb, Zn) and to determine the potentially bioavailable metals. Additionally, the enrichment ratio for each element analyzed was calculated. The mineralogical composition of sediment samples and cores were obtained by X-ray diffraction. Moreover, data of orbital remote sensing were used in order to detect and quantify suspended matter by applying a logarithmic algorithm. Geochemical data of bottom sediments and cores revealed that, excepting Ba and Pb, the elements analyzed presented concentrations characteristic of an unpolluted ecosystem (Al: 0,25 - 8,76 %; Ba: 3,03 - 870 ?g.g-1; Cd: < 0,25 ?g.g-1; Cr: 1,72 - 82,4 ?g.g-1; Cu: 0,12 -25,3 ?g.g-1; Pb: 0,38 - 23,7 ?g.g-1; Fe: 0,10 - 5,82 %; Mn: 15,1 - 815 ?g.g-1; Ni: 0,14 - 36,1 ?g.g-1; Zn: 1,37 - 113 ?g.g-1). During the dry season a distribution pattern was observed, with higher metal concentrations in the margins, decreasing toward the central portion of the channel. These metal concentrations were well correlated with mineralogical compositions, with clay minerals prevailing at the margins, and quartz and feldspar in the center. However, this pattern was not observed during the wet season, probably because of the high water flux that disturbed bottom sediments. But, as observed for the dry season, a good correlation between metal concentrations and mineralogical composition was also observed for the wet season, with high metal concentrations where there were high quantities of clay minerals. Low enrichment ratios were obtained for the majority of elements analyzed, excepting for Mn, Ba and Pb. Manganese presented the higher ratios downstream for both seasons, and it can be an evidence of anthropogenic impact by shrimp farming. As barium and lead concentrations in sediment samples presented analytical problems during the total sample digestion, one cannot be sure that the ratios obtained correspond to the reality. The highest metal concentrations in particulate matter were obtained in the portion dominated by fluvial transport for all metals analyzed, excepting for copper. Barium and zinc were the only elements that presented elevated concentrations that are not common of unpolluted ecosystems (Ba: 5730 - 8355 ?g.g-1; Zn: 3899 - 4348 ?g.g-1). However, these high concentrations could not be related to the shrimp farming and waste waters from the town of Canguaretama, once they were obtained from the fluvial particulate matter, that is upstream from the activities above mentioned. The application of the logarithmic algorithm to the processed LANDSAT image was well succeeded, although the acquired image does not correspond exactly to the field campaigns. The IKONOS image provided very detailed views of the suspended sediment concentration at the estuary, as the mixture of distinct water flows at the confluence of Cunha? and Curimata? rivers, with more turbid waters from Cunha? river, that is directly affected by effluents from shrimp farming and urban waste waters deriving from the town of Canguaretama / O estu?rio do rio Curimata? localiza-se na por??o sul do litoral oriental do Estado do Rio Grande do Norte, apresentando uma das ?ltimas por??es de manguezais no Estado. Este ecossistema tem sido fortemente afetado por diversas atividades antropog?nicas, como o cultivo de cana-de-a??car, a carcinicultura, al?m da urbaniza??o. Trabalhos anteriores neste local revelaram que ostras Crassostrea rhizophorae apresentaram concentra??es de alguns metais acima dos limites permitidos para consumo, e que talvez a entrada destes metais no estu?rio estivesse relacionada aos efluentes de carcinicultura. Para uma melhor compreens?o da origem destes metais, foram coletadas amostras de sedimento de fundo, testemunhos e material particulado em suspens?o para uma caracteriza??o das concentra??es de dez elementos maiores e tra?os (Al, Ba, Cd, Cu, Cr, Fe, Mn, Ni, Pb, Zn), bem como para a determina??o dos elementos potencialmente biodispon?veis. Al?m disso, tamb?m foi realizado o c?lculo da raz?o de enriquecimento para cada elemento analisado. A composi??o mineral?gica das amostras de sedimento de fundo e dos testemunhos foi obtida atrav?s de difratometria de raios-X. Adicionalmente, dados de sensoriamento remoto orbital foram usados a fim de se detectar e semiquantificar o material particulado em suspens?o atrav?s da aplica??o de um algoritmo logar?tmico. As an?lises geoqu?micas das amostras de sedimento de fundo revelaram que os elementos analisados apresentaram concentra??es caracter?sticas de um estu?rio n?o polu?do (Al: 0,25 a 8,76%; Ba: 3,03 a 870 ?g.g-1; Cd: < 0,25 ?g.g-1; Cr: 1,72 a 82,4 ?g.g-1; Cu: 0,12 a 25,3 ?g.g-1; Pb: 0,38 a 23,7 ?g.g-1; Fe: 0,10 a 5,82 %; Mn: 15,1 a 815 ?g.g-1; Ni: 0,14 a 36,1 ?g.g-1; Zn: 1,37 a 113 ?g.g-1). Um padr?o de distribui??o dos metais foi observado durante a esta??o seca, com maiores concentra??es nas margens, diminuindo em dire??o ao centro do canal. A concentra??o dos metais se mostrou bem correlacionada com as respectivas composi??es mineral?gicas das amostras de sedimento, com minerais de argila predominando nas margens, e quartzo e feldspato mais presentes no centro do canal. Contudo, este padr?o n?o foi observado durante a esta??o chuvosa, provavelmente devido ao fluxo de ?gua mais intenso que promoveu o dist?rbio dos sedimentos de fundo, com remo??o da fra??o fina das margens. Mas, da mesma forma que observado para a esta??o seca, nas amostras coletadas durante a esta??o chuvosa tamb?m se observou maiores concentra??es de metais nas amostras com predom?nio de minerais argilosos. Raz?es de enriquecimento sugestivas de aus?ncia de polui??o foram obtidas para a maioria dos elementos analisados, com exce??o de Mn. O mangan?s apresentou as maiores raz?es ? jusante da atividade de carcinicultura, as quais sugerem polui??o significativa neste trecho durante ambas as esta??es seca e chuvosa. Esta pode ser uma evid?ncia do impacto da carcinicultura no estu?rio, j? que a montante desta atividade a raz?o de enriquecimento foi baixa. No material particulado em suspens?o as maiores concentra??es de metais foram obtidas na por??o dominada pelo transporte fluvial para todos os elementos analisados, com exce??o do cobre. Os ?nicos elementos que apresentaram concentra??es elevadas, incomuns para ambientes livres de polui??o, foram b?rio (de 5730 a 8355 ?g.g-1) e zinco (de 3899 a 4348 ?g.g-1). Contudo, estas concentra??es anormais aparentam n?o estar relacionadas ? carcinicultura ou aos efluentes da cidade de Canguaretama, uma vez que foram encontrados ? montante destas atividades. A aplica??o do algoritmo logar?tmico ? imagem LANDSAT foi bem sucedida, embora a imagem adquirida n?o corresponda exatamente ?s datas de coleta do material em suspens?o. A imagem IKONOS forneceu vis?es muito detalhadas do estu?rio que permitiram observar a distribui??o do material particulado, com a mistura de fluxos de ?gua distintos na conflu?ncia dos rios Cunha? e Curimata?, sendo que o rio Cunha? apresenta ?guas mais turvas, e ? diretamente afetado pelos efluentes de carcinicultura e dejetos urbanos da cidade de Canguaretama