- MeSH
- dentální fluoróza etiologie prevence a kontrola MeSH
- fluor * analýza škodlivé účinky MeSH
- lidé MeSH
- pitná voda * chemie normy škodlivé účinky MeSH
- podzemní voda chemie MeSH
- vodní zdroje normy MeSH
- znečištění vody * MeSH
- Check Tag
- lidé MeSH
- Geografické názvy
- Etiopie MeSH
There are two principal sources of arsenic in Zimapán. Point sources are linked to mining and smelting activities and especially to mine tailings. Diffuse sources are not well defined and are linked to regional flow systems in carbonate rocks. Both sources are caused by the oxidation of arsenic-rich sulfidic mineralization. Point sources are characterized by Ca-SO(4)-HCO(3) ground water type and relatively enriched values of deltaD, delta(18)O, and delta(34)S(SO(4)). Diffuse sources are characterized by Ca-Na-HCO(3) type of ground water and more depleted values of deltaD, delta(18)O, and delta(34)S(SO(4)). Values of deltaD and delta(18)O indicate similar altitude of recharge for both arsenic sources and stronger impact of evaporation for point sources in mine tailings. There are also different values of delta(34)S(SO(4)) for both sources, presumably due to different types of mineralization or isotopic zonality in deposits. In Principal Component Analysis (PCA), the principal component 1 (PC1), which describes the impact of sulfide oxidation and neutralization by the dissolution of carbonates, has higher values in samples from point sources. In spite of similar concentrations of As in ground water affected by diffuse sources and point sources (mean values 0.21 mg L(-1) and 0.31 mg L(-1), respectively, in the years from 2003 to 2008), the diffuse sources have more impact on the health of population in Zimapán. This is caused by the extraction of ground water from wells tapping regional flow system. In contrast, wells located in the proximity of mine tailings are not generally used for water supply.
- MeSH
- analýza hlavních komponent MeSH
- arsen analýza MeSH
- časové faktory MeSH
- chemické látky znečišťující vodu analýza MeSH
- difuze MeSH
- geologické sedimenty analýza chemie MeSH
- hornictví MeSH
- izotopy analýza chemie MeSH
- kyslík analýza MeSH
- monitorování životního prostředí MeSH
- oxidace-redukce MeSH
- pohyb vody MeSH
- sírany analýza MeSH
- sulfidy analýza MeSH
- uhličitany analýza MeSH
- zásobování vodou analýza MeSH
- zeměpis MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Mexiko MeSH
Over a period of several decades multiple leaks of large volumes from storage facilities located near Hnevice (Czech Republic) have caused the underlying Quaternary aquifer to be severely contaminated with nonaqueous phase liquid (NAPL) petroleum hydrocarbons. Beginning in the late 1980's the NAPL plume started to shrink as a consequence of NAPL dissolution exceeding replenishment and due to active remediation. The subsurface was classified geochemically into four different zones, (i) a contaminant-free zone never occupied by NAPL or dissolved contaminants, (ii) a re-oxidation zone formerly occupied by NAPL, (iii) a zone currently occupied by NAPL, and (iv) a lower fringe zone between the overlying NAPL and the deeper underlying contaminant-free zone. The study investigated the spatial and temporal variability of the redox zonation at the Hnevice site and quantified the influence of iron-cycling on the overall electron balance. As a first step inverse geochemical modelling was carried out to identify possible reaction models and mass transfer processes. In a subsequent step, two-dimensional (forward) multi-component reactive transport modelling was performed to evaluate and quantify the major processes that control the geochemical evolution at the site. The study explains the observed enrichment of the lower fringe zone with ferrihydrite as a result of the re-oxidation of ferrous iron. It suggests that once the NAPL zone started to shrink the dissolution of previously formed siderite and FeS by oxygen and nitrate consumed a significant part of the oxidation capacity for a considerable time period and therefore limited the penetration of electron acceptors into the NAPL contaminated zone.
- MeSH
- biodegradace MeSH
- chemické látky znečišťující vodu MeSH
- financování organizované MeSH
- geologické jevy MeSH
- geologie MeSH
- látky znečišťující půdu metabolismus MeSH
- monitorování životního prostředí MeSH
- oxidace-redukce MeSH
- ropa metabolismus MeSH
- teoretické modely MeSH
- uhlovodíky metabolismus MeSH
- železo metabolismus MeSH
- Geografické názvy
- Česká republika MeSH
