TY - GEN
T1 - Monitored natural attenuation for an arsenic contaminated industrial site with sulfate reducing aquifer conditions
T2 - 4th International Congress on Arsenic in the Environment, As 2012
AU - Stauder, S.
AU - Werner, P.
PY - 2012/8/16
Y1 - 2012/8/16
N2 - Groundwater investigations on the site of a former pulp mill with high content of arsenic showed that several heavy and semi-metals were mobilized over decades out of iron-slag deposits in the topsoil (residues from pyrite burning). With the exception of arsenic, all elements were fixed directly in the underlying water-saturated region due to sulfate reducing aquifer conditions. Arsenic forms under those conditions unique soluble arsenic-sulfur species (up to 2 mg As/L in the hot spot), which have been identified as thioarsenates by IC-ICP/MS. However, within a flow distance of about 60 m, the thioarsenates are immobilized in the aquifer. Laboratory tests and thermodynamic calculations suggest that in the prevailing sulfate-reducing, iron-containing environment arsenic is immobilized as arsenopyrite. These findings and a mass balance for the involved reacting agents enabled the prognosis of long term arsenic immobilization. This was a pre-condition of the authorities to establish a Monitored Natural Attenuation (MNA) concept in 2002. The results from subsequent 8 years of hydraulic and analytical monitoring confirmed the adequacy of this approach.
AB - Groundwater investigations on the site of a former pulp mill with high content of arsenic showed that several heavy and semi-metals were mobilized over decades out of iron-slag deposits in the topsoil (residues from pyrite burning). With the exception of arsenic, all elements were fixed directly in the underlying water-saturated region due to sulfate reducing aquifer conditions. Arsenic forms under those conditions unique soluble arsenic-sulfur species (up to 2 mg As/L in the hot spot), which have been identified as thioarsenates by IC-ICP/MS. However, within a flow distance of about 60 m, the thioarsenates are immobilized in the aquifer. Laboratory tests and thermodynamic calculations suggest that in the prevailing sulfate-reducing, iron-containing environment arsenic is immobilized as arsenopyrite. These findings and a mass balance for the involved reacting agents enabled the prognosis of long term arsenic immobilization. This was a pre-condition of the authorities to establish a Monitored Natural Attenuation (MNA) concept in 2002. The results from subsequent 8 years of hydraulic and analytical monitoring confirmed the adequacy of this approach.
UR - http://www.scopus.com/inward/record.url?scp=84864876059&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84864876059&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:84864876059
SN - 9780415637633
T3 - Understanding the Geological and Medical Interface of Arsenic, As 2012 - 4th International Congress: Arsenic in the Environment
SP - 293
EP - 294
BT - Understanding the Geological and Medical Interface of Arsenic, As 2012 - 4th International Congress
Y2 - 22 July 2012 through 27 July 2012
ER -