Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Sorption and desorption of arsenic from sandy soils: Column studies
Rate‐limited sorption/desorption can have a profound effect upon the transport of sorbing contaminants. Numerical and analytical models used to predict chemical movement through the subsurface rarely incorporate the effects of nonlinear sorption and desorption kinetics, resulting in potentially large overestimates of mass extractability. Mass transfer characteristics of arsenic‐contaminated soils at the site of a former arsenical herbicide manufacturer in Houston, Texas, were examined in the laboratory using soil columns. Unaffected soils comprised of silty sands to coarse sands were collected from the uppermost aquifer. Two soil columns were loaded with a known mass of mixed organic and inorganic forms of arsenic resident in site ground water. A third control column was prepared with dry 20 × 30 mesh ASTM silica sand. Leachate samples were collected from each void volume until arsenic breakthrough was achieved. The dynamic test applied a continuing head of water, operating in an upflow mode through 4‐in. diameter by 12‐in. long soil columns repacked to in situ density. A flow‐through velocity of one void volume per day was chosen for arsenic loading to the columns and 0.08 void volume per day during the desorption phase of the test. Uncontaminated ground water was then passed through the columns, and the tests were restarted in the desorption mode. Analysis of the leachate and resulting arsenic concentrations in the test columns allowed for the calculation of distribution coefficients that describe arsenic behavior. Measured distribution coefficients during desorption ranged from 0.26 after one void volume to 3.3 after six void volumes had been passed through the column.
Sorption and desorption of arsenic from sandy soils: Column studies
Rate‐limited sorption/desorption can have a profound effect upon the transport of sorbing contaminants. Numerical and analytical models used to predict chemical movement through the subsurface rarely incorporate the effects of nonlinear sorption and desorption kinetics, resulting in potentially large overestimates of mass extractability. Mass transfer characteristics of arsenic‐contaminated soils at the site of a former arsenical herbicide manufacturer in Houston, Texas, were examined in the laboratory using soil columns. Unaffected soils comprised of silty sands to coarse sands were collected from the uppermost aquifer. Two soil columns were loaded with a known mass of mixed organic and inorganic forms of arsenic resident in site ground water. A third control column was prepared with dry 20 × 30 mesh ASTM silica sand. Leachate samples were collected from each void volume until arsenic breakthrough was achieved. The dynamic test applied a continuing head of water, operating in an upflow mode through 4‐in. diameter by 12‐in. long soil columns repacked to in situ density. A flow‐through velocity of one void volume per day was chosen for arsenic loading to the columns and 0.08 void volume per day during the desorption phase of the test. Uncontaminated ground water was then passed through the columns, and the tests were restarted in the desorption mode. Analysis of the leachate and resulting arsenic concentrations in the test columns allowed for the calculation of distribution coefficients that describe arsenic behavior. Measured distribution coefficients during desorption ranged from 0.26 after one void volume to 3.3 after six void volumes had been passed through the column.
Sorption and desorption of arsenic from sandy soils: Column studies
Kuhlmeier, Paul D. (Autor:in)
Journal of Soil Contamination ; 6 ; 21-36
01.01.1997
16 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Unbekannt
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