| 1. |
- Engelmann, Pamela de Medeiros, et al.
(författare)
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Environmental monitoring of water resources around a municipal landfill of the Rio Grande do Sul state, Brazil
- 2017
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 24:26, s. 21398-21411
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Tidskriftsartikel (refereegranskat)abstract
- In Brazil, landfills are commonly used as a method for the final disposal of waste that is compliant with the legislation. This technique, however, presents a risk to surface water and groundwater resources, owing to the leakage of metals, anions, and organic compounds. The geochemical monitoring of water resources is therefore extremely important, since the leachate can compromise the quality and use of surface water and groundwater close to landfills. In this paper, the results of analyses of metals, anions, ammonia, and physicochemical parameters were used to identify possible contamination of surface water and groundwater in a landfill area. A statistical multivariate approach was used. The values found for alkali metals, nitrate, and chloride indicate contamination in the regional groundwater and, moreover, surface waters also show variation when compared to the other background points, mainly for ammonia. Thus, the results of this study evidence the landfill leachate influence on the quality of groundwater and surface water in the study area.
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| 2. |
- Melo, Clarissa L., et al.
(författare)
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Integration results of soil CO2 flux and subsurface gases in the Ressacada Pilot site, Southern Brazil
- 2017
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Ingår i: 13th International Conference on Greenhouse Gas Control Technologies, GHGT-13. - : Elsevier. ; , s. 3793-3804
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Konferensbidrag (refereegranskat)abstract
- The first CO2 monitoring field lab at the Ressacada Farm, in the Southern region of Brazil, started in 2011 and until 2015 offered an excellent opportunity to run controlled CO2 releases experiments in soil and shallow subsurface through vertical injection wells. This paper focus on the presentation and comparison of the results obtained at the last campaign realized at this site in August 2015. The results integrate a time-lapse monitoring experiment of CO2 migration in both saturated and unsaturated sand-rich sediments and soil, using soil CO2 flux measurements and subsurface gas analyses through CO2 concentrations (ppm) and carbon isotope ratios (delta C-13 of CO2). The CO2 flux results in the studied area showed an increase in the flux values according to the increasing of injection rate and along the campaign are directed to the southwest portion of the area. However, even by injecting large amounts of CO2, fluxes are greatly reduced when it rains. The gas analysis also showed an increase in CO2 concentrations according to the increasing of the injection rate mainly in the superficial levels of the monitoring wells (0.5m and 2m depth). The delta C-13 of CO2 found on the 3rd injection day showed the presence of CO2 injected and demonstrate that the sampling methodology with vacutainer vial was effective, since there is no atmospheric contamination. The correlation of isotopic analysis were consistent with the results of concentrations and CO2 fluxes and thus, it is clear that the CO2 breakthrough occurred from the 3rd day of injection, while were obtained the largest CO2 fluxes, the higher gas concentrations in the subsurface, as well as the industrial origin of delta C-13 of CO2.
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| 3. |
- Rodrigues, Luiz Frederico, et al.
(författare)
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The influence of methane fluxes on the sulfate/methane interface in sediments from the Rio Grande Cone Gas Hydrate Province, southern Brazil : A influência dos fluxos de metano na interface sulfato/metano em sedimentos de hidrato de gás do Cone do Rio Grande, Sul do Brasil
- 2017
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Ingår i: Brazilian Journal of Geology. - : FapUNIFESP (SciELO). - 2317-4692 .- 2317-4889. ; 47:3, s. 369-381
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Tidskriftsartikel (refereegranskat)abstract
- Much research has been published regarding the relation between major gas hydrate accumulations and the global carbon cycle. In this context, the determination of the sulfate/methane interface (SMI) depth is of primary importance in order to understand the dynamics of methane flux in the shallow section. This paper identifies the depth of the SMI in sediments based on sulfate and methane concentration profiles in cores recovered in the Rio Grande Cone Gas Hydrate Province, Pelotas Basin, southern Brazil. The shape of methane and sulfate concentration profiles in the sediments can be linked to the local methane flux rate as follows: (i) near linear, high upward-diffusing methane flux coupled with high sulfate diffusion from seawater; (ii) irregular, variable methane flux rates; and (iii) kink-type profile, which is indicative of variable rather than strictly high upward methane flux. The areas in which a high methane flux was identified are spatially associated with gas chimneys in sediments within pockmarks, whereas profiles with low methane flux are present in adjacent areas. These chimneys appear as acoustic blankings in seismic records and can therefore be mapped in subsurface. The wavy-like seismic reflection following the SMI coincides with the occurrence of authigenic carbonate nodules and concretions. In addition, high methane fluxes and the occurrence of concretions and nodules carbonates were correlated by stratigraphic position of the concretions bearing intervals and sulfate profiles
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