title: The transport and reaction behavior of arsenic in groundwater : experiments and case studies
creator: Höhn, Rouven
subject: ddc-550
subject: 550 Earth sciences
description: The transport and reaction behavior of arsenic in the aquatic environment is of high importance, since arsenic in groundwater causes serious problems e.g. in Bangladesh. It is well known that elevated arsenic concentrations in drinking water lead to severe health risk. Various investigations have been carried out concerning the oxidation and adsorption of arsenic in the environment, but less is know about the reduction and release of arsenic.  A continuous injection tracer test was conducted at the USGS Cape Cod research site (Mass.,USA) in order to investigate natural reduction of As(V) to As(III) in an iron reducing environment. As(V) reduction was observed to take place under the conditions of this aquifer. Furthermore retardation of As(III) turned out to be minor than the one of As(V). Microbial investigations showed that arsenic reducing microorganism as well as iron reducers and sulfate reducers were present in the aquifer. Arsenic was assumed to be reduced by microbial reduction as well as by dissolved sulfide. To support this theory batch experiments with As(V) and sulfide were conducted. In preliminary experiments at pH 3, up to 30 % was reduced depending on the sulfide. Water samples buffered a pH 6.8 showed lower reduction rates. Batch experiments with MnO2 apparently indicated manganese reduction to prevent arsenic reduction. In batch experiments with Fe(III), a simultaneous reduction of Fe(III) and As(V) was observed. The third part of the work deals with the arsenic release from ore and mine dumps. For a better understanding of the flow and the reaction path of arsenic sediment samples from two sites on Sardinia highly influenced by ore and mine dumps were analyzed. In all sediment samples the total amount of arsenic as well as of Ca, Mn, Fe, S and Pb were measured. Different elution methods were conducted to make predictions of the mobility as well as the arsenic binding. In the first study area, the arsenic is transported in a stream in which the flow rate differs extremely over the year. High flow rates cause translocation processes of the tailing material and the stream sediments. During periods with low flow rates the arsenic transport is dominated by the dissolved fraction. In the other study area the arsenic is released in a wetland and in this case the transport is mostly controlled by geochemical conditions. Thus the As transport velocity is slow and the accumulation rates are much lower compared to the other study area.
date: 2005
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/5732/1/Diss_Hoehn.pdf
identifier: DOI:10.11588/heidok.00005732
identifier: urn:nbn:de:bsz:16-opus-57322
identifier:   Höhn, Rouven  (2005) The transport and reaction behavior of arsenic in groundwater : experiments and case studies.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/5732/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng