Sediment analysis and water quality assessment in the Pixquiac basin: drinking water supply of Xalapa city (Veracruz, Mexico).

Fluvial sediment analysis and water quality assessment are useful to identify anthropic and natural sources of pollution in rivers. Currently, there is a lack of information about water quality in the Pixquiac basin (Veracruz state, Mexico), and this scarcity of data prevents authorities to take adequate measures to protect water resources. The basin is a crucial territory for Xalapa, the capital city of Veracruz state, as it gets 39% of its drinkable water from it. This research analyzed 10 physicochemical parameters and 12 metal concentrations in various rivers and sources during two seasons. Dissolved metals presented average concentrations (µg/L): Al (456.25) > Fe (199.4) > Mn (16.86) > Ba (13.8) > Zn (7.6) > Cu (1.03) > Pb (0.27) > As (0.12) > Ni (0.118) (Cd, Cr and Hg undetectable). Metals in sediment recorded average concentrations (ppm): Fe (38575) > Al (38425) > Mn (460) > Ba (206.2) > Zn (65.1) > Cr (29.8) > Ni (20.9) > Cu (16.4) > Pb (4.8) > As (2.1) (Cd and Hg undetectable). During the rainy season, Water Quality Index (WAWQI) classified stations P17 and P18's water as "unsuitable for drinking" with values of 110.4 and 117.6. Enrichment factor (EF) recorded a "moderate enrichment" of Pb in sediment in P24. Pollution was mainly explained by wastewater discharges in rivers but also because of erosion and rainfall events. Statistical analysis presented strong relationships between trace and major metals which could explain a common natural origin for metals in water and sediment: rock lixiviation.

Spatial and Temporal Variations of Vanadium and Cadmium in Surface Water from the Yucatan Shelf.

Surface water samples from the Yucatan shelf presented Cd concentrations similar to those reported internationally for non-polluted coastal and marine waters. V concentrations, on the other hand, fall within the range of anthropogenically polluted waters (25% of the sampling sites). In the study area, the probable sources of V could be: (1) carbonate sediments leaching V into the water column and co-transported with fine sediments resuspending as a result of the complex hydrodynamics in the area or, (2) accidental spills from cargo ships transporting oil between the Atlantic and the Gulf of Mexico. Significant spatial and temporal differences were found for both metals; therefore, a regional interval concentration is suggested for V from 1.28 to 1.84 µg L-1 and Cd from 0.003 to 0.09 µg L-1. These differences could primarily be the result of the observed hydrology and hydrodynamics created by the Yucatan current, submarine groundwater discharges and upwelling.

Natural contents of heavy metals in soils of the southern Amazonas state, Brazil / Teores naturais de metais pesados em solos da região sul do estado do Amazonas

Heavy metals occur naturally in the soil as a product of rock weathering and, are commonly associated with environmental pollution and toxicity to living beings. This association deserves much attention since some heavy metals, such as Fe, Mn, Cu, Zn, and Ni, are essential to plants. Our attention should thus be drawn not only to the element itself, but also to its contents in the soil. This is because its occurrence and quantities are covariates of the geomorphic, geologic, pedologic, and anthropogenic diversity. In this context, the present study aimed to determine the natural contents of heavy metals in the soils of three physiographic regions of the south of Amazonas state, comparing them to natural contents in some other Brazilian soils. Twenty-four soil samples were collected in three physiographic regions (field/forest, animated relief, and flooded/non-flooded areas), in the superficial and subsurface horizons. The digestion of the samples was based on the EPA-3051A method and the determination by atomic absorption spectrophotometry (AAnalyst 800 Perkin Elmer). The results indicate a low potential of soils from the south of Amazonas in supplying heavy metals, which were found in the following decreasing order: Ba>Fe>Cr>Pb>Zn>Cu>Mn>Co>Cd. The natural heavy metal contents vary depending on the type of soil, weathering level, and physiographic regions, and are similar or inferior to those observed in other regions of the country; with Neosols presenting the highest natural contents; and Cambisols, the lowest, for most of the metals evaluated.(AU)

Os metais pesados ocorrem naturalmente no solo como produto do intemperismo das rochas e, comumente, são associados com poluição ambiental e toxidade aos seres vivos. Essa relação merece atenção mais cautelosa, uma vez que alguns são essenciais às plantas como Fe, Mn, Cu, Zn e Ni. Assim, a preocupação deve estar voltada não apenas ao elemento em si, mas aos teores desses no solo, visto que sua ocorrência e quantidade são covariativas da diversidade geomorfológica, geológica, pedológica e antrópica. Neste sentido, objetivou-se determinar os teores naturais dos metais pesados nos solos de três regiões fisiográficas da região Sul do Amazonas, comparando-os com os teores naturais de alguns solos do país. Foram coletadas 24 amostras de solo em três regiões fisiográficas (Campo/Floresta, Relevo Movimentado e Várzea/Terra Firme), nos horizontes superficiais e subsuperficiais. A digestão das amostras baseou-se no método EPA-3051A, e a determinação com espectrofotometria de absorção atômica (AAnalyst 800 Perkin Elmer). Os resultados indicam baixo potencial dos solos do Sul do Amazonas em suprir metais pesados, sendo os maiores teores encontrados na seguinte ordem decrescente: Ba>Fe>Cr>Pb>Zn>Cu>Mn>Co>Cd. Os teores naturais de metais pesados variam em função da classe de solo, grau de intemperismo e das regiões fisiográficas e são semelhantes ou inferiores aos observados em outras regiões do país; com Neossolos apresentando teores naturais mais elevados e, os Cambissolos, os mais baixos, para a maioria dos metais avaliados.(AU)

Natural contents of heavy metals in soils of the southern Amazonas state, Brazil / Teores naturais de metais pesados em solos da região sul do estado do Amazonas

Heavy metals occur naturally in the soil as a product of rock weathering and, are commonly associated with environmental pollution and toxicity to living beings. This association deserves much attention since some heavy metals, such as Fe, Mn, Cu, Zn, and Ni, are essential to plants. Our attention should thus be drawn not only to the element itself, but also to its contents in the soil. This is because its occurrence and quantities are covariates of the geomorphic, geologic, pedologic, and anthropogenic diversity. In this context, the present study aimed to determine the natural contents of heavy metals in the soils of three physiographic regions of the south of Amazonas state, comparing them to natural contents in some other Brazilian soils. Twenty-four soil samples were collected in three physiographic regions (field/forest, animated relief, and flooded/non-flooded areas), in the superficial and subsurface horizons. The digestion of the samples was based on the EPA-3051A method and the determination by atomic absorption spectrophotometry (AAnalyst 800 Perkin Elmer). The results indicate a low potential of soils from the south of Amazonas in supplying heavy metals, which were found in the following decreasing order: Ba>Fe>Cr>Pb>Zn>Cu>Mn>Co>Cd. The natural heavy metal contents vary depending on the type of soil, weathering level, and physiographic regions, and are similar or inferior to those observed in other regions of the country; with Neosols presenting the highest natural contents; and Cambisols, the lowest, for most of the metals evaluated.

Os metais pesados ocorrem naturalmente no solo como produto do intemperismo das rochas e, comumente, são associados com poluição ambiental e toxidade aos seres vivos. Essa relação merece atenção mais cautelosa, uma vez que alguns são essenciais às plantas como Fe, Mn, Cu, Zn e Ni. Assim, a preocupação deve estar voltada não apenas ao elemento em si, mas aos teores desses no solo, visto que sua ocorrência e quantidade são covariativas da diversidade geomorfológica, geológica, pedológica e antrópica. Neste sentido, objetivou-se determinar os teores naturais dos metais pesados nos solos de três regiões fisiográficas da região Sul do Amazonas, comparando-os com os teores naturais de alguns solos do país. Foram coletadas 24 amostras de solo em três regiões fisiográficas (Campo/Floresta, Relevo Movimentado e Várzea/Terra Firme), nos horizontes superficiais e subsuperficiais. A digestão das amostras baseou-se no método EPA-3051A, e a determinação com espectrofotometria de absorção atômica (AAnalyst 800 Perkin Elmer). Os resultados indicam baixo potencial dos solos do Sul do Amazonas em suprir metais pesados, sendo os maiores teores encontrados na seguinte ordem decrescente: Ba>Fe>Cr>Pb>Zn>Cu>Mn>Co>Cd. Os teores naturais de metais pesados variam em função da classe de solo, grau de intemperismo e das regiões fisiográficas e são semelhantes ou inferiores aos observados em outras regiões do país; com Neossolos apresentando teores naturais mais elevados e, os Cambissolos, os mais baixos, para a maioria dos metais avaliados.

Un método para evaluar el enriquecimiento de metales en sedimentos marinos en Costa Rica / A method to evaluate metal enrichment in marine sediments

A method to evaluate metal enrichment in marine sediments. In order to evaluate metal enrichment in sediments , a method is proposed and tested in Bahia Culebra and the Golfo de Nicoya, Costa Rica through the normalization of the elements against aluminum, and by linear regression of the logarithm of the concentrations of different elements respect to aluminum. The distributions of the elements manganese, and strontium of Bahía Culebra did not satisfy the tests of normalization and linear regression, indicating a nonnatural distribution or enrichment of these elements in this region. In the Golfo de Nicoya the elements copper , zinc , rubidium and the strontium did not satisfy the test of normality or the linear regression with respect to aluminum, indicating a possible enrichment of these elements. The majority of the concentrations of the elements in two sample sites, with the exception of chromium, are within the natural ranges in rocks or clays of marine sediments, and within the concentration ranges of other studies done in these same regions. Chromium has average values beyond the natural concentrations, the values of some samples in the Golfo de Nicoya are up to 10 times greater than the concentration value of a typical bay with high contamination of this element.

Se propone un método para evaluar enriquecimiento de metales en sedimentos de Bahía Culebra y en el Golfo de Nicoya de Costa Rica a través de la normalización de los elementos y el aluminio usando la regresión lineal de las concentraciones de los elementos y el Aluminio. Las distribuciones de los elementos manganeso y el estroncio de Bahía Culebra no cumplen con las pruebas de normalización y de regresión lineal, indicando una distribución no natural o enriquecimiento de estos elementos en esta región. En el Golfo de Nicoya los elementos cobre, zinc, rubidio y el estroncio no cumplen ya sea con la hipótesis de normalidad o con la regresión lineal respecto al aluminio, indicando un posible enriquecimiento de estos elementos en esta región. La mayoría de las concentraciones de los elementos tanto en ambos sitios de muestreo, con excepción del cromo, se encuentran dentro de los ámbitos naturales encontrados en las rocas o en las arcillas de sedimentos marinos a nivel mundial, y dentro de los ámbitos de las concentraciones de otros estudios realizados en estas mismas regiones. El cromo muestra valores promedio más allá de las concentraciones naturales, siendo la concentración de algunas muestras en el Golfo de Nicoya hasta diez veces mayores que el valor de una bahía con alta contaminación de este elemento.