Antonio Pedro Viero

Groundwater vulnerability assessment in coastal plain of Rio Grande do Sul State, Brazil, using drastic and adsorption capacity of soils

Groundwater vulnerability assessment to delineate areas that are more susceptible to contamination has become an important element for resource management and land use planning. The objective of this work was to integrate hydrogeologic data in a geographic information system (GIS) for phreatic groundwater vulnerability assessment of a pilot area from the Coastal Plain of the Rio Grande do Sul State, Brazil, using the DRASTIC method and adsorption capacity of soils. The studied ions were copper, lead, sulfate and phosphate. Using the original DRASTIC method, the vulnerability presented high values, mainly due to the texture of the sediments and the low depths of waters, which favor the accessibility of the contaminants to the groundwaters. DRASTIC with adsorption capacity of soils showed specifics results for each studied ion. Groundwater vulnerability to metals in relationship to anions was lower. These results show that the original DRASTIC method represents better contaminants with high mobility.

Environmental impact and geochemical behavior of soil contaminants from an industrial waste landfill in Southern Brazil

Industrial waste landfills produce great impacts on soil and groundwater. There are many industrial waste landfills in Vale dos Sinos, Southern Brazil, which were inadequately planned and maintained since the industry started in the first half of the twentieth century. The largest industrial landfill in the Valley, which causes the most severe impacts on soil and groundwater, is the subject of this paper, which studies the environmental impacts and behavior of contaminants in soil. The landfill was carefully mapped on a scale of 1:1,000; 88 samples were collected from soil probes; the leachate of three samples was comprehensively analyzed; and soils mineralogy and chemistry were studied. Few studies have been made on this landfill. This study shows widespread contamination of soil in the surrounding areas of the landfill. Chromium, chloride and ammonium have the highest contamination levels, reflecting their high contents in landfill leachate. Contamination by petroleum hydrocarbons, cyanide and mercury is registered in more than 65% of soil samples with low concentrations. Lead, copper and barium show low contamination restricted to a few soil samples. Soil contamination occurs mainly in the unsaturated zone of the aquifer at the convergence points of stormwater, showing that the preferential transport of contaminants occurs on surface flow followed by soil infiltration. The results of leaching tests indicate high metal sorption capacity of soil. The remediation of contaminated soil must contain at least the following actions: sealing the top of the landfill, installation of geochemical barriers, removal of the liquid waste basins without sealing the base and collection and treatment of the rainwater drainage.

Fluoride in the Serra Geral Aquifer System: Source Evaluation Using Stable Isotopes and Principal Component Analysis

Groundwater with anomalous fluoride content and water mixture patterns were studied in the fractured Serra Geral Aquifer System, a basaltic to rhyolitic geological unit, using a principal component analysis interpretation of groundwater chemical data from 309 deep wells distributed in the Rio Grande do Sul State, Southern Brazil. A four-component model that explains 81% of the total variance in the Principal Component Analysis is suggested. Six hydrochemical groups were identified. δ18O and δ2H were analyzed in 28 Serra Geral Aquifer System samples in order to identify stable isotopes patterns and make comparisons with data from the Guarani Aquifer System and meteoric waters. The results demonstrated a complex water mixture between the Serra Geral Aquifer System and the Guarani Aquifer System, with meteoric recharge and ascending water infiltration through an intensive tectonic fracturing.

Caracterização hidrogeológica e hidroquímica das águas subterrâneas da região de São Gabriel, RS

O presente estudo trata da caracterizacao hidrogeologica e hidroquimica das aguas subterrâneas do municipio de Sao Gabriel, RS. Foram analisadas 55 amostras de agua provenientes de 55 pocos tubulares profundos de diversas localidades e variados contextos hidrogeologicos. A maior parte do territorio do municipio de Sao Gabriel e constituida por rochas sedimentares da Bacia do Parana. Assim, os principais aquiferos possuem aguas com composicoes quimicas bastante diversificadas, refletindo variados ambientes deposicionais e composicoes mineralogicas. Subordinadamente, aquiferos fraturados formados por rochas granitico-gnaissicas do Escudo Sul- -rio-grandense ocorrem na porcao sul do municipio. Desta forma, a qualidade das aguas subterrâ- neas do municipio varia de acordo com as condicoes geologicas de cada unidade aquifera e com as relacoes entre elas. Na area, os elementos Fluor e Sodio sao os parâmetros que comprometem a utilizacao das aguas subterrâneas para fins de consumo humano, dessedentacao de animais e irrigacao. Cerca de 30 % das analises apresentam aguas improprias para consumo com relacao a estes ions, conforme parâmetros maximos permitidos pelo Ministerio da Saude do Brasil. Os principais aquiferos da regiao, em termos quantitativos e qualitativos, sao o Aquifero Rio Bonito (ARB) e o Sistema Aquifero Guarani (SAG), localizados, respectivamente, na porcao sul e nordeste do municipio. As aguas dos pocos que captam destes aquiferos sao de boa qualidade, potaveis e as vazoes podem ser consideradas como as melhores da regiao .

Utilização de solos locais para tratamento de efluentes do refino de petróleo contendo metais

The employment of local soils for extraction of metallic elements was evaluated through batch tests to treat wastewaters generated in a petroleum refinery plant in southern Brazil. Clay and organic carbon content and clay mineralogy provide these soils, in principle, with moderate metal retention capacity. The following retention order was established: Cr3+ > Pb2+ > Cu2+ > Hg2+ > Cd2+, with total amount of metals retained varying from 36 to 65 meq kg-1. The results show the high efficiency of local soils for extracting metals from liquid effluents through sorption and precipitation processes under acid pH conditions.

Origin of high fluoride contents in groundwater of the Santa Maria Formation, Guarany Aquifer System, southern Brazil

A comprehensive assessment of man-made impact on the environment is much kept behind because of missing unified systems of environmental monitoring. They represent sources of reliable information on the current status of the environment, as well as the absence of approaches to assess the impact of chemical pollution by different anthropogenic sources. Vegetation, being the component of environmental systems, is very sensitive to atmospheric man-made load. However, permissible concentrations of elements in plants, causing deflection in their development are differently estimated in different regions and vegetation species. As to the Baikal region, it is commonly the sanitary state of woods, that is primarily assessed. Coniferous trees, in particular pine, represent the main tree species in the region. In the Olkhon region we investigated the trace element compositions in pine needles to obtain the background contents of toxic metals. This region of the National park lies 300 km away from the industrial sources of pollutants, beyond the zone of wind effect, and has no industry. The research was made on the healthy (green) and dried up (red) pine needles. The elements like Zn, A1, Mn, Fe, Cr, Cu, Co, Ni, Sr, Cd, Pb, Li, Rb, Sb and As were measured by atomic absorption and flame emission photometry. The samples were decomposed in autoclaves with the mixture of nitric acid and hydrogen peroxide. Distinct differences were found in a series of elements contained in the green and dried needles. The red needles are characterized by higher contents of Zn, A1, Cu and low Mn, Fe, Pb with similar contents of other elements. It is proposed to use the ratio Fe/Mn for evaluating the ecological status and characterization of the damage to trees. In the study region in the green needles Fe/Mn=0.5, in red ones it is 0.7 (for comparison the ratio Fe/Mn in the zone of industry influence the ratio is 1.1-2.0). The obtained values of metal concentrations in the green pine needles can be accepted as background in the assessment of the sanitary state of the Prebaikalian woods, and reddening of the needles most likely reflects the natural serial level of tree stands.