This paper presents a case study for a complex contaminated groundwater site impacted by a historical release of chlorinated solvents in Silicon Valley, California. The original conceptual site model (CSM) inferred a ...This paper presents a case study for a complex contaminated groundwater site impacted by a historical release of chlorinated solvents in Silicon Valley, California. The original conceptual site model (CSM) inferred a contaminant migration pathway based on the groundwater gradient interpreted from groundwater elevation data, which is based on the underlying assumption that the subsurface conditions are homogeneous. However, the buried channel deposits render the underlying geology highly heterogeneous, and this heterogeneity plays a significant role in the subsurface migration of contaminants. Chemical fingerprinting evidence suggested that contamination at the downgradient property boundary was related to an off-site contaminant source. But, this alone was not a compelling argument. However, Environmental Sequence Stratigraphy (ESS), a geology-based environmental forensic technique, was applied to define the permeability architecture or the “plumbing” that controls subsurface fluid flow and contaminant migration. First, the geologic and depositional setting was synthesized based on regional geologic data, and representative facies models were identified for the site. Second, the existing CSM and site lithology data were reviewed and existing lithology data were graphically presented to display vertical grain-size patterns. This analysis focused on the nexus between the depositional environment and the site-specific subsurface data resulting in correlations/interpretations between and beyond data points that are based on established stratigraphic principles. The depositional environment results in buried river channels as the primary control on subsurface fluid flow, which defines hydrostratigraphic units (or HSUs). Finally, a hydrostratigraphic CSM that includes maps and cross sections was constructed to depict the HSUs present as a framework to integrate hydro-geology and chemistry data. This study demonstrates that: 1) Highly per-meable buried river channel deposits control subsurface fluid flow and contaminant transport, and have distinct chemical constituents and concentrations (i.e., they represent distinct HSUs), 2) Mapping of such HSUs is feasible with existing boring log data, 3) In settings such as the Santa Clara Valley where groundwater flow is governed by subsurface channel deposits, a hydrostratigraphic mapping approach is superior to a depth-based aquifer zonation approach, and 4) For heterogeneous subsurface, a detailed geology-based definition of the subsurface is an integral component of an environmental forensic analyses to determine contaminant source(s) and pathways.展开更多
A new convenient and environmentally benign procedure for synthesis of azines from hydrazme sulfate with several aromatic aldehydes coupled with grinding is studied. This reaction is carried out under solvent-free con...A new convenient and environmentally benign procedure for synthesis of azines from hydrazme sulfate with several aromatic aldehydes coupled with grinding is studied. This reaction is carried out under solvent-free conditions and in absence of catalyst to afford high yields of relevant azines.展开更多
The research in room temperature ionic liquid is reviewed. The present status and development prospect of its applications to environmental chemistry are introduced in detail. As high performance environmental solvent...The research in room temperature ionic liquid is reviewed. The present status and development prospect of its applications to environmental chemistry are introduced in detail. As high performance environmental solvents, the room temperature ionic liquids can be applied to treating oil shale, purifying nature gas, and processing nuclear fuel; they can also be used in organic synthesis reactions, such as Diels Alder reaction, Friedel Crafts reaction, transition metal catalyzed reaction, regioselective alkylation. They can be used as the substitutes for traditional strong acid catalysts in alkylation of polycyclic aromatic hydrocarbon, esterification of acetic acid with alcohols, Beckmann rearrangement reaction, hydrogenation and polymerization of aromatic compounds.展开更多
文摘This paper presents a case study for a complex contaminated groundwater site impacted by a historical release of chlorinated solvents in Silicon Valley, California. The original conceptual site model (CSM) inferred a contaminant migration pathway based on the groundwater gradient interpreted from groundwater elevation data, which is based on the underlying assumption that the subsurface conditions are homogeneous. However, the buried channel deposits render the underlying geology highly heterogeneous, and this heterogeneity plays a significant role in the subsurface migration of contaminants. Chemical fingerprinting evidence suggested that contamination at the downgradient property boundary was related to an off-site contaminant source. But, this alone was not a compelling argument. However, Environmental Sequence Stratigraphy (ESS), a geology-based environmental forensic technique, was applied to define the permeability architecture or the “plumbing” that controls subsurface fluid flow and contaminant migration. First, the geologic and depositional setting was synthesized based on regional geologic data, and representative facies models were identified for the site. Second, the existing CSM and site lithology data were reviewed and existing lithology data were graphically presented to display vertical grain-size patterns. This analysis focused on the nexus between the depositional environment and the site-specific subsurface data resulting in correlations/interpretations between and beyond data points that are based on established stratigraphic principles. The depositional environment results in buried river channels as the primary control on subsurface fluid flow, which defines hydrostratigraphic units (or HSUs). Finally, a hydrostratigraphic CSM that includes maps and cross sections was constructed to depict the HSUs present as a framework to integrate hydro-geology and chemistry data. This study demonstrates that: 1) Highly per-meable buried river channel deposits control subsurface fluid flow and contaminant transport, and have distinct chemical constituents and concentrations (i.e., they represent distinct HSUs), 2) Mapping of such HSUs is feasible with existing boring log data, 3) In settings such as the Santa Clara Valley where groundwater flow is governed by subsurface channel deposits, a hydrostratigraphic mapping approach is superior to a depth-based aquifer zonation approach, and 4) For heterogeneous subsurface, a detailed geology-based definition of the subsurface is an integral component of an environmental forensic analyses to determine contaminant source(s) and pathways.
文摘A new convenient and environmentally benign procedure for synthesis of azines from hydrazme sulfate with several aromatic aldehydes coupled with grinding is studied. This reaction is carried out under solvent-free conditions and in absence of catalyst to afford high yields of relevant azines.
文摘The research in room temperature ionic liquid is reviewed. The present status and development prospect of its applications to environmental chemistry are introduced in detail. As high performance environmental solvents, the room temperature ionic liquids can be applied to treating oil shale, purifying nature gas, and processing nuclear fuel; they can also be used in organic synthesis reactions, such as Diels Alder reaction, Friedel Crafts reaction, transition metal catalyzed reaction, regioselective alkylation. They can be used as the substitutes for traditional strong acid catalysts in alkylation of polycyclic aromatic hydrocarbon, esterification of acetic acid with alcohols, Beckmann rearrangement reaction, hydrogenation and polymerization of aromatic compounds.
