Desorption of Arsenic from Calcareous Mine Affected Soils by Phosphate Fertilizers Application in Relation to Soil Properties and as Partitioning (original) (raw)

Mechanisms of Arsenic Adsorption in Calcareous Soils

Journal of Agriculture and …, 2009

There are many factors which affects the As adsorption in soil. The concentration of phosphate (PO4) is the main factor which affects the As adsorption negatively, and organic matter (OM) has also negative affect on the As adsorption because both OM and PO4 has a ...

Adsorption of arsenic (As) in soils and in their clay fraction

Adsorption of arsenic by three soils and their clay fractions were studied separately in order to evaluate their potential in reducing arsenic mobility and bioavailability, and the possible application of this' technique for the remediation of soils contaminated with arsenic. The soil series selected were Ghior (high clay content), Ghatail (medium clay content) and Rajoir (organic soil). The maximum amount of arsenic was adsorbed by Ghior soil, followed by the Ghatail soil while the minimum was adsorhed by the organic soil, the Rajoir soil. Variations in adsorption of As among soils were attributed to the content and nature of the clay fractions, presence of organic matter, iron content and magnitude of CEC. A positive relationship (r = 0.9079) was noticed between the adsorption of arsenic and clay content of the soils. A fairly noticeable inverse relationship was observed between the adsorption of arsenic and organic matter (r =-0.9577), Fe content (r =-0.8584) and cation exchange capacity (r =-0.9316) of the soils. Adsorption of arsenic by clay fractions of the corresponding soils showed somewhat similar trend to that of the adsorption of arsenic by soils. The extent of adsorption appeared to have varied with the variation of mineral types in the clay fractions of the soils. The illitic minerals present in the clay fractions were probably mainly responsible for the adsorption of arsenic.

Arsenic in Soils Affected by Mining: Microscopic Studies vs. Sequential Chemical Extraction

International Journal of Environmental Research and Public Health

Soil samples from three inactive mines, corresponding to different Arsenic-bearing mineralization types, were collected and studied. The aim was to determine the influence of mine wastes mineralogy/geochemistry and texture in As mobility and to compare results from sequential chemical extraction and microscopic techniques (optical and electron) at a grain scale. Arsenic in soils is found mainly associated to the residual fraction, indicating that mechanical As dispersion is mainly responsible for As soil pollution. The use of objective microscopic techniques (i.e., Scanning Electron Microscopy-Energy Dispersive Spectroscopy -SEM-EDS-, High Resolution Transmission Electron Microscopy -HR-TEM) has pointed out that the selected sequential extraction method overestimates the role of Mn amorphous oxy-hydroxides and organic matter in As retention while underestimating the mechanism of As adsorption onto clay particle surfaces.