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Open Access item Arsenic copper and zinc leaching through preferential flow in mining-impacted soils
O´Day, Peggy A.
García Guinea, Javier
|Keywords:||Effective cation exchange capacityECEC, Extended x-ray adsorption fine structure EXAFS|
|Publisher:||Sociedad Americana de la Ciencia del Suelo|
|Abstract:||The effect of preferential fl ow on the spatial distribution of As, Cu, and Zn
and chemical speciation of As was studied within the surface riverbed (RB)
layer of a small stream that collects surface runoff from an As-bearing waste
pile of an abandoned mine. Water fl ow domains, preferential (PF) or matrix
(MF), were identifi ed by staining techniques. In-stream soils had lower pH and
higher As, Cu, Zn, and Fe concentrations than soils outside the stream channel.
Mean metal(loid) concentrations were higher in RB samples than in the subsoil
(SS), but no strong correlations were found in the RB between metal(loids) and
either PF or MF, with the exception of Zn and MF paths. In contrast, in the SS,
PF paths were associated with lower Cu and Zn concentrations and higher concentrations
of As, extractable Fe, and total organic C compared with MF soils.
Analysis of SS samples by As x-ray absorption spectroscopy (XAS) indicated
that As was present only as arsenate sorbed to Fe(III) oxide phases, and Fe XAS
showed a higher proportion of ferrihydrite, in addition to illite–smectite, in a
PF than a MF sample. Results indicate an overall transport of contaminants and
Fe from storage in RB soils, where fl ow regimes are heterogeneous, into the SS
as a result of acid leaching. In the SS, preferential fl ow domains act as conduits
for transport of Cu and Zn into the soil matrix but retain As heterogeneously
through sorption on amorphous Fe(III) oxides that may dissolve and precipitate
|Description:||14 páginas, ilustraciones y tablas estadísticas.|
|Publisher version (URL):||http://dx.doi.org/10.2136/sssaj.2011.0269|
|Appears in Collections:||(ICA) Artículos|
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