Cylindrical vector beam sorter with spin-dependent spiral transformation.

Here, we propose and experimentally demonstrate a cylindrical vector beam (CVB) sorter based on a spin-dependent spiral transformation. By exploiting the spin-orbital interaction of the geometric phase, a pair of conjugated spiral transformations are applied to modulate the two orthogonal circularly polarized components of the CVB, which are converted into the same linear phase gradient from opposite azimuthal phase gradients. Since the orthogonal spin components of CVBs with different polarization orders carry different phase gradients, under the convergence of a convex lens, the coaxially transmitted CVBs can be sorted with spatially separated positions, and the increased phase gradient provided by the spiral transformation yields the high resolution.

Effects of three low-molecular-weight organic acids (LMWOAs) and pH on the mobilization of arsenic and heavy metals (Cu, Pb, and Zn) from mine tailings.

Natural organic acids may play an important role in influencing the mobility of toxic contaminants in the environment. The mobilization of arsenic (As) and heavy metals from an oxidized Pb-Zn mine tailings sample in the presence of three low-molecular-weight organic acids, aspartic acid, cysteine, and succinic acid, was investigated at a mass ratio of 10 mg organic additive/g mine tailings in this study. The effect of pH was also evaluated.

Effect of natural organic matter on arsenic mobilization from mine tailings.

This research study was to elucidate the mechanisms of arsenic mobilization from mine tailings in the presence of natural organic matter (NOM). Humic acid (HA) was chosen as a model for NOM. The introduction of the HA at a low mass ratio (below 2mg added HA/g mine tailings) inhibited arsenic mobilization under acidic conditions.

On the potential of biological treatment for arsenic contaminated soils and groundwater.

Bioremediation of arsenic contaminated soils and groundwater shows a great potential for future development due to its environmental compatibility and possible cost-effectiveness. It relies on microbial activity to remove, mobilize, and contain arsenic through sorption, biomethylation-demethylation, complexation, coprecipitation, and oxidation-reduction processes. This paper gives an evaluation on the feasibility of using biological methods for the remediation of arsenic contaminated soils and groundwater.

Enhanced mobilization of arsenic and heavy metals from mine tailings by humic acid.

Arsenic and heavy metal mobilization from mine tailings is an issue of concern as it might pose potential groundwater or ecological risks. Increasing attention recently has been focused on the effects of natural organic matter on the mobility behavior of the toxicants in the environment. Column experiments were carried out in this research study to evaluate the feasibility of using humic acid (HA) to mobilize arsenic and heavy metals (i.

Speciation and surface structure of inorganic arsenic in solid phases: a review.

Accurate determination of individual arsenic species is critical because the toxicology, mobility, and adsorptivity of arsenic vary substantially with its chemical forms and oxidation states. Separation techniques together with techniques for chemical identification make it possible to determine the combinational forms and oxidation states of arsenic in solid phases. Selective sequential extraction is often employed to determine operationally defined fractions, but it has a poor precision and selectivity.

Natural attenuation processes for remediation of arsenic contaminated soils and groundwater.

Arsenic (As) contamination presents a hazard in many countries. Natural attenuation (NA) of As-contaminated soils and groundwater may be a cost-effective in situ remedial option. It relies on the site intrinsic assimilative capacity and allows in-place cleanup.

Effect of natural organic matter on arsenic release from soils and sediments into groundwater.

Arsenic (As) contamination in groundwater has received significant attention recently. Natural and anthropogenic sources contribute to the worldwide occurrence of As contamination. As speciation is an important factor related to its toxic and mobile behavior.

Occurrence of arsenic contamination in Canada: sources, behavior and distribution.

Recently there has been increasing anxieties concerning arsenic related problems. Occurrence of arsenic contamination has been reported worldwide. In Canada, the main natural arsenic sources are weathering and erosion of arsenic-containing rocks and soil, while tailings from historic and recent gold mine operations and wood preservative facilities are the principal anthropogenic sources.

An evaluation of surfactant foam technology in remediation of contaminated soil.

Soil contamination is notoriously difficult to treat because the contaminants are often tightly bound to the soil particles. Conventional remediation technologies are becoming less popular due to the high treatment costs. This paper gives a comprehensive overview and evaluation of an emerging promising alternative, surfactant foam technology.