Metal contamination of vineyard soils in wet subtropics (southern Brazil

The vine-growing areas in Brazil are the dampest in the world. Copper maximum value registered in this study was as much as 3200 mg kg_1, which is several times higher than reported for vineyard soils in temperate climates. Other pesticide-derived metals accumulate in the topsoil layer, surpassing in the old vineyards the background value several times for Zn, Pb, Cr and Cd. Copper is transported to deeper soils’ horizons and can potentially contaminate groundwater. The soils from basaltic volcanic rocks reveal the highest values of Cu extracted with CaCl2, demonstrating a high capacity of copper transference into plants. When evaluating the risks of copper’s toxic effects in subtropics, the soils from rhyolitic volcanic rocks are more worrisome, as the Cu extracted with ammonium acetate 1 M surpasses the toxic threshold as much as 4e6 times

Sediment geochemistry of marine shallow-water hydrothermal vents in Mapachitos, Bahía Concepción, Baja California peninsula, Mexico

The objective of this study was to determine the influence of marine shallow-water hydrothermal systems in Mapachitos, bahia Concepcion, on the composition of surficial sediments in the surrounding area of this bay. The following elements Al, As, Ba, Ca, Cd, Co, Cs, Cu, Fe, Hg, Li, Mn, Mo, Ni, Rb, S, Ti, U, V, Zn, Corg, and Cinorg were determined in sediment samples. The calculated CaCO3 values in the sediments within some spots of the study area were as high as 90% (with an average of 61 %). The concentration of organic carbon in the sediments was approximately 1%. The total element contents in the sediments were compared with Earth's crustal average, and enrichment factors (EF) were calculated using Al as normalizing element. The results showed that the most of the elements (Ba, Co, Cs, Cu, Fe, Li, Mn, Ni, Rb, Ti, U, V, and Zn) are conservative, with average EF close to unity. Lithium, mollybdenum and uranium were enriched in the sediments with average values of EF between 2 and 10. The highest average EF determined in the study were for the following elements: As, Ca, Cd, and Hg. The average concentrations of potentially toxic elements in the sediments from the Mapachitos vents were 60 mg kg-1 for As, and 21849 µg kg-1 for Hg. The surface sediments of the adjacent area, however, have low average concentrations for As and Hg: 3.7 mg kg-1 and 52 µg kg-1, respectively. Other elements such as Cd (0.9 mg kg-1) and Ca (28.3%) are highly enriched in the sediments of the study area, comparing to their average crustal abundances. The results of Principal Component Analysis allowed to determine three factors which explain 91% of data variance, as well as to differentiate four associations including terrigenous elements, calcareous components, elements of the hydrothermal origin and redox-sensitive elements in the surface sediments off the Mapachitos in the north-western portion of bahia Concepcion. Furthermore, the results confirmed the influence of the hydrothermal inputs of some trace elements on the sediments of the area surrounding the vents, in particular As and Hg, and to a lesser extent Al, Fe, and Mn at the venting site.El objetivo de este estudio fue determinar la influencia de las ventilas hidrotermales someras en Mapachitos, Bahía Concepción, en la composición de los sedimentos superficiales del área circundante de esta bahía. Los siguientes elementos Al, As, Ba, Ca, Cd, Co, Cs, Cu, Fe, Hg, Li, Mn, Mo, Ni, Rb, S, Ti, U, V, Zn, Corgy Cinorgfueron determinados en muestras de sedimentos. Los valores de CaCO3 calculado en los sedimentos dentro de algunospuntos del área de estudio son tan altos como 90% (con un promedio de 61%). La concentración de carbono orgánico en los sedimentosfue aproximadamente 1%. Los contenidos totales de los elementos fueron comparados con las abundanciaspromediospara la corteza continental, y los factores de enriquecimiento (EF) fueron calculados usando Al como elemento normalizador. Los resultados demostraron que la mayoría de los elementos (Ba, Co, Cs, Cu, Fe, Li, Mn, Ni, Rb, Ti, U, V, y Zn) son conservativos, con promedios de EF cercanos a la unidad. El litio, el molibdeno y el uranio fueron enriquecidos en los sedimentos con valorespromedios EF entre 2y 10. Los mayorespromedios de EF en el estudio fueron para los siguientes elementos: As, Ca, Cd y Hg. Las concentraciones promedio de elementos potencialmente toxicos en los sedimentos de las ventilas en Mapachitos, fueron 60 mg kg-1 para As y 21849 µg kg-1 para Hg. Los sedimentos superficiales del área adyacente, sin embargo, tienen bajas concentraciones promedios para As y Hg: 3.7 mg kg-1 y 52 µg kg-1, respectivamente. Otros elementos tales como Cd (0.1 mg kg-1) y Ca (64%) son altamente enriquecidos en los sedimentos del área de estudio, comparando sus abundancias promedios con los de la corteza. Los resultados del análisis de Componentes Principales permitieron identificar tres factores los cuales explican el 91% de la varianza de los datos, asi como también diferenciar algunas asociaciones incluyendo elementos terrígenos, componentes calcáreos, elementos de origen hidrotermal y elementos de reducción -oxidación sensibles en los sedimentos superficiales frente a Mapachitos en la porción noroeste de la bahía Concepción. Además, los resultados confirman la influencia de las agregaciones hidrotermales de algunos elementos traza en el área circundante a las ventilas, en particular, As y Hg, y en grado menor Al, Fe y Mn en el sitio de las ventila

Sulfate reduction and alterability of sulfur species in sediments of an estuary with irregular hydrological regime

The irregular hydrological regime in Patos Lagoon estuary has been suggested as having a distinctive influence on sulfur speciation in sediments. We performed an investigation for different prolonged hydrological conditions focusing on the distribution of sulfides (acid volatile sulfide (AVS), chromium reducible sulfide (CRS), and Free-S2-) in sediment cores from salt marsh and non-vegetated shallow zone. Significant differences in sulfides content and distribution between the different hydrological periods were found. The predominance of more reducing conditions was observed during the freshwater period. It reflects a higher total reducible inorganic sulfur (TRIS) content in this period, with a great accumulation of AVS in sediments (> 100 mg kg-1). In the maximum salinity period, more oxidizing conditions prevailed, which significantly decreased the concentrations of metastable sulfides. The intense bioirrigation process exerts control over sulfide formation and distribution, which is as important as that exerted by the variations of the hydrological regime

Effects of iron-ore mining and processing on metal bioavailability in a tropical coastal lagoon

In water systems, water quality and geochemical properties of sediments determine the speciation of trace metals, metal transport, and sediment-water exchange, influencing metal availability and its potential effects on biota. Studies from temperate climates have shown that iron-ore mining and tailing wastewaters, besides being a source of trace metals, usually show high levels of dissolved ions and particulate suspended matter, thus having the potential of indirectly changing metal bioavailability. For the first time in the tropics, we identified the effects of iron-ore mining and processing on metal bioavailability in a coastal lagoon. With an extensive sampling scheme, we investigated the potential sources of metals; the links among metal levels in water, sediments, and invertebrates; and the contrasting effects on metal speciation and bioavailability. The metals Fe, Mn, Al, Cr, Zn, Cu, Ni, Pb, Cd, Hg, and As were measured in water, sediments (surface and profiles), and invertebrates from Mãe-Bá Lagoon and in the sites directly influenced by the mining operations (tailing dams and nearby rivers). In addition, samples from two other lagoons, considered pristine, were analyzed. The study area is located in the southeast of Brazil (Iron Quadrangle Region and a coastal area of Espírito Santo State). General water characteristics included pH, dissolved organic carbon, alkalinity, and anion composition. Water metal speciation was assessed by a speciation model (Chemical Equilibria in Aquatic Systems). Grain-size distribution, organic carbon, carbonate, and acid volatile sulfide (AVS) were determined in sediments. Statistical methods included comparison of means by Mann-Whitney test, ordination and correlation analyses, and analysis of regression for geochemical normalization of metals with grain size. The dissolved metal concentrations, the total metal levels in sediments, and the normalization based on the fine sediment fraction showed that the mining operations constitute potential sources of Fe, Mn, Cr, Cu, Ni, Pb, As, and Hg to Mãe-Bá Lagoon. However, trace metal availability was reduced because of increased pH, hardness, and sulfide content (356 μmol/g) in the sites influenced by the mining. The lagoon showed similar water chemistry as in the mining sites, with metal bioavailability further decreased by the presence of dissolved organic carbon and chloride. Although AVS levels in the lagoon were low (0.48-56 μmol/g), metal bioavailability was reduced because of the presence of organic matter. Metal levels in invertebrates confirmed the predicted low metal bioavailability in Mãe-Bá Lagoon. The lagoon was considered moderately contaminated only by Hg and As. The iron-ore mining and processing studied here constitute potential sources of metal pollution into the tropical lagoon. Contrary to expectations, however, it also contributes to reducing the overall metal bioavailability in the lagoon. These findings are believed to be useful for evaluating metal exposure in a more integrated way, identifying not only the sources of pollution but also how they can affect the components involved in metal speciation and bioavailability in water systems, leading to new insights

Sources and levels of rain acidity in the region of the Rio Grande city, RS, Brazil

The current article presents the first data on physical-chemical parameters of wet precipitation collected at single collection point in the city of Rio Grande, during the period of 12 months in 1997-1998. The employed technique of rainwater separation into several portions made clear the process of the atmosphere self-purification during a precipitation event. The pH of rainwater depends on the extent of industrial emissions and increases during a precipitation event. The first portion of rainwater shows an obvious neutralizing effect of soil and ocean-derived components, whose intensity depends on the duration of the preceding dry period

Mercury pollution in land reclamation fills from the colonial period of the Brazil’s southernmost

Land reclamation fills in the city of Rio Grande (RS) are polluted by mercury with concentrations ranging from 0.3 to 18.7 mg kg-1. The level of Hg pollution decreases from the oldest landfills of 18th century to recent ones. Mercury distribution along vertical profiles resembles the same for copper, lead, and zinc, what allow supposing that mercury distribution has an autochthonous character. It is suggested that the principal source of mercury pollution was the activities related to animal skin and fair hair treatment, using ancient technology known as "carroting". Similar scenario of environmental risk could be met in other Brazilian cities with similar colonization history

Evaluation of the air pollution by particulate lead: geochemical approach

High lead concentrations up to 5478 mg kg-1 were detected in dry atmospheric precipitations in Rio Grande city and adjacent area. Lead anomalies cover up to 30% of the study area. Lead concentration measurement in dry atmospheric precipitation and suspended particulate matter provides a possibility to detect concentrations above lead threshold in the air. The most impacted areas are fishermen’s villages. The most possible source of lead in the air is uncontrolled sub industrial activity of local population

Mercury contamination of soil as the result of long-term phosphate fertilizer production

This study was aimed at determining the range and spatial distribution of mercury in a geographical area influenced by the emissions of phosphate fertilizers industries in Rio Grande, Brazil. The case study demonstrated that mercury concentrations in a fine fraction of the surface soil close to the fertilizer factory reached levels as high as 800 µg kg-1. Increased mercury concentrations were detected up to 60 cm below the soil surface. Further, a significant impact of the elevated mercury levels was manifested in a 1-km zone around the factory. Technical grade sulfuric acid employed in superphosphate production is considered the principal source of this mercury contaminationInstituto Politécnico Nacional (IPN). Centro Interdisciplinario de Ciencias MarinasCiencias marinasPD

What is geochemistry of landscape?

Geochemistry of landscape is an area within the Geography that was created in Russia on the 20th century. It investigates the landscape at the chemical elements level and has its own classification of landscapes based on both biotic and abiotic parameters. Geochemical mapping of landscapes has applications in agriculture, environmental protection, medical geography and ore prospecting. The application of this method in tropical zones has not been propagated yet. The development of landscapegeochemical studies in these zones will have significant theoretical and applied value for the modern geography