Removal of mercury from sediment by ultrasound combined with biomass (transgenic Chlamydomonas reinhardtii).

As one of the most pervasive environmental problems, Hg pollution in sediment is particularly difficult to remediate because it cannot be decomposed. The application of ultrasound combined with biomass (transgenic Chlamydomonas reinhardtii (C. reinhardtii), a green alga) for the removal of Hg from model and contaminated sediments (Al(2)O(3), α-HgS, and PACS-2 marine sediment) was investigated in this study.

Linking solid phase speciation of Pb sequestered to birnessite to oral Pb bioaccessibility: implications for soil remediation.

Lead (Pb) sorption onto oxide surfaces in soils may strongly influence the risk posed from incidental ingestion of lead-contaminated soils. In this study, Pb was sorbed to a model soil mineral, birnessite, and was placed in a simulated gastrointestinal tract (in vitro) to simulate the possible effects of ingestion of a soil contaminated with Pb. The changes in Pb speciation were determined using extended X-ray absorption fine structure and X-ray absorption near edge spectroscopy.

Sonolytic desorption of mercury from aluminum oxide: effects of pH, chloride, and organic matter.

The effects of pH, Cl-, and humic acid (HA) on sonolytic desorption of Hg(II) from aluminum oxide were examined. Results showed that Hg(II) desorption was achieved by lowering the pH from 7.0 to 4.

Sonochemical dissolution of cinnabar (alpha-HgS).

To investigate the sonochemical dissolution of cinnabar, sulfur oxidation products (S(ox)) and dissolved Hg(II) released into the aqueous solution were determined. Detected S(ox), in the presence of ultrasound suggests that dissolution of cinnabar occurred. Terephthalic acid (TA) used to scavenge *OH in bulk solution formed from sonication showed that oxidative dissolution occurred in both the bulk solution and the interfacial areas of cavitation bubbles.

Bioaccessibility of lead sequestered to corundum and ferrihydrite in a simulated gastrointestinal system.

Lead (Pb) sorption onto oxide surfaces in soils may strongly influence the risk posed from incidental ingestion of Pb-contaminated soil. Lead was sorbed to model oxide minerals of corundum (alpha-Al(2)O(3)) and ferrihydrite (Fe(5)HO(8).4H(2)O).

Bioaccessibility of arsenic(V) bound to ferrihydrite using a simulated gastrointestinal system.

The risk posed from incidental ingestion to humans of arsenic-contaminated soil may depend on sorption of arsenate (As(V)) to oxide surfaces in soil. Arsenate sorbed to ferrihydrite, a model soil mineral, was used to simulate possible effects on ingestion of soil contaminated with As-(V) sorbed to Fe oxide surfaces. Arsenate sorbed to ferrihydrite was placed in a simulated gastrointestinal tract (in vitro) to ascertain the bioaccessibility of As(V) and changes in As(V) surface speciation caused by the gastrointestinal system.

Cr(VI) reduction and immobilization by magnetite under alkaline pH conditions: the role of passivation.

This study investigated Cr(VI) reduction and immobilization by magnetite under alkaline pH conditions similar to those present at the Hanford site. Compared to acidic and neutral pH, chromium(VI) reduction by magnetite at high pH conditions is limited (<20% of potential reduction capacity), and the extent of reduction does not vary significantly with increasing NaOH concentration. This is due to the formation of maghemite, goethite, and/or Fe1-xCrxOOH, which may form a passivation layer on the magnetite surface, stopping further chromate reduction.

Sonolytic desorption of mercury from aluminum oxide.

As discrete particles and/or as coatings on other mineral surfaces in natural systems, aluminum (hydr)oxides are efficient sinks for Hg(II). Ultrasound at 20 kHz was applied to enhance the desorption of Hg(II) from aluminum oxide particles (5.0 micromol of Hg g(-1)).

Chemical and physical properties of dry flue gas desulfurization products.

Beneficial and environmentally safe recycling of flue gas desulfurization (FGD) products requires detailed knowledge of their chemical and physical properties. We analyzed 59 dry FGD samples collected from 13 locations representing four major FGD scrubbing technologies. The chemistry of all samples was dominated by Ca, S, Al, Fe, and Si and strong preferential partitioning into the acid insoluble residue (i.

Inhibited Cr(VI) reduction by aqueous Fe(II) under hyperalkaline conditions.

This study investigated Cr(VI) reduction by dissolved Fe(II) in hyperalkaline pH conditions as found in fluid wastes associated with the U.S. nuclear weapons program.

Abiotic degradation of pentachloronitrobenzene by Fe(III): reactions on goethite and iron oxide nanoparticles.

Pentachloronitrobenzene is a fungicide that is degraded in anoxic soils and sediments through unknown processes that are often thought to be biologically mediated. The present research describes the kinetics for the abiotic reduction of this compound in aqueous Fe(II)/goethite systems at near-neutral pH values. The results provide evidence for a rate-affecting surface-association process rather than a direct (i.

Ralstonia basilensis M91-3, a denitrifying soil bacterium capable of using s-triazines as nitrogen sources.

The purpose of this study was to characterize the phylogenetic and phenotypic traits of M91-3, a soil bacterium capable of mineralizing atrazine (2-chloro-4-N-isopropyl-6-N-ethyl-s-triazine). The isolate was identified as Ralstonia basilensis based on 99.5% homology of the 16S rRNA sequence and various chemotaxonomic data.

Fate of polydimethylsilicone in biosolids-amended field plots.

This research examined the fate of polydimethylsilicones (PDMS) in agricultural test plots amended with municipal biosolids. This 4 yr field study involved addition of 0, 15, and 100 Mg ha(-1) of municipal biosolids, which contained ambient concentrations of PDMS (1272 mg kg(-1) biosolids), to corn and soybean test plots. Soil samples collected at intermittent time intervals were analyzed for soil water, soil organic C, extractable PDMS and PDMS hydrolysis products.

Sorptive Characteristics of Acridine-Surfactant-Phyllosilicate Systems.

The effects of the presence of a cationic surfactant on the sorption of two typical nitrogen heterocyclic compounds (NHCs) on swelling and nonswelling phyllosilicates were investigated. The addition of a cationic surfactant to a NHC-phyllosilicate system can either solubilize the sorbed NHC molecules or immobilize the suspended NHC molecules, depending upon the concentration and sequence of the surfactant added. The presence of surfactant molecules on the clay mineral surfaces promoted sorption of more neutral NHC molecules due to hydrophobic effect, and this resulted in a considerable increase in sorption at high pH conditions.