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Conditions redox hétérogènes, mobilité de l’arsenic et écoulement souterrain dans un aquifère de roches fracturées près d’un site de décharge du New Hampshire, USA Condiciones redox heterogéneas, movilidad del arsénico y flujo de agua subterránea en un acuífero de roca fracturada cerca de un sitio repositorio de residuos en New Hampshire, EEUU 美国新罕布什尔州一废弃处置场附近的裂隙含水层中非均质氧化还原条件,砷的迁移性和地下水流 Condições de redox heterogéneas, mobilidade de arsénio e fluxo subterrâneo num aquífero fraturado nas vizinhanças de um aterro de resíduos em New Hampshire, EUA | Heterogeneous redox conditions, arsenic mobility, and groundwater flow in a fractured-rock aquifer near a waste repository site in New Hampshire, USA Texte intégral
2012
Harte, Philip T. | Ayotte, Joseph D. | Hoffman, Andrew J. | Revesz, Kinga M. | Belaval, Marcel | Lamb, Steven | Bohlke, J. K.
Anthropogenic sources of carbon from landfill or waste leachate can promote reductive dissolution of in situ arsenic (As) and enhance the mobility of As in groundwater. Groundwater from residential-supply wells in a fractured crystalline-rock aquifer adjacent to a Superfund site in Raymond, New Hampshire, USA, showed evidence of locally enhanced As mobilization in relatively reducing (mixed oxic-anoxic to anoxic) conditions as determined by redox classification and other lines of evidence. Redox classification was determined from geochemical indicators based on threshold concentrations of dissolved oxygen (DO), nitrate (NO 3 – ), iron (Fe2+), manganese (Mn2+), and sulfate (SO 4 2– ). Redox conditions were evaluated also based on methane (CH4), excess nitrogen gas (N2) from denitrification, the oxidation state of dissolved As speciation (As(III) and As(V)), and several stable isotope ratios. Samples from the residential-supply wells primarily exhibit mixed redox conditions, as most have long open boreholes (typically 50–100 m) that receive water from multiple discrete fractures with contrasting groundwater chemistry and redox conditions. The methods employed in this study can be used at other sites to gauge redox conditions and the potential for As mobilization in complex fractured crystalline-rock aquifers where multiple lines of evidence are likely needed to understand As occurrence, mobility, and transport.
Afficher plus [+] Moins [-]Une approche de modélisation hybride pour évaluer le système d’écoulement des eaux souterraines aux niveaux bas et intermédiaire du site de stockage de déchets radioactifs de Gyeong-Ju en Corée du Sud Una aproximación de modelo híbrido para evaluar el sistema de flujo de agua subterránea de un repositorio de residuos radiactivos de nivel bajo e intermedio en Gyeong-Ju, Corea 用一种混合建模方法评估韩国庆州市中低放废物处置场地下水流系统 한국 경주 중저준위 폐기물 처분 부지의 지하수 유동 시스템 평가를 위한 혼합 모형 접근 방법 Uma abordagem de modelação híbrida para analisar o sistema de fluxo subterrâneo no local de armazenamento de resíduos radioativos de nível baixo a intermédio em Gyeong-Ju, Coreia | A hybrid modeling approach to evaluate the groundwater flow system at the low- and intermediate-level radioactive waste disposal site in Gyeong-Ju, Korea Texte intégral
2012
Ji, Sung-Hoon | Park, Kyung Woo | Lim, Doo-Hyun | Kim, Chunsoo | Kim, Kyung Su | Dershowitz, William
The development and implementation of a hybrid discrete fracture network/equivalent porous medium (DFN/EPM) approach to groundwater flow at the Gyeong-Ju low- and intermediate-level radioactive waste (LILW) disposal site in the Republic of Korea is reported. The geometrical and hydrogeological properties of fractured zones, background fractures and rock matrix were derived from site characterization data and implemented as a DFN. Several DFN realizations, including the deterministic fractured zones and the stochastic background fractures, whose statistical properties were verified by comparison with in-situ fracture and hydraulic test data, were suggested, and they were then upscaled to continuums using a fracture tensor approach for site-scale flow simulations. The upscaled models were evaluated by comparison to in-situ pressure monitoring data, and then used to simulate post-closure hydrogeology for the LILW facility. Simulation results demonstrate the importance of careful characterization and implementation of fractured zones. The study highlighted the importance of reducing uncertainty regarding the properties and variability of natural background fractures, particularly in the immediate vicinity of repository emplacement.
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