Tungsten sodium is a widely used transition metal for which very limited information on environmental and toxicological effects is available. Of particular a interest is the lack of information linking tungsten speciation and environmental effects. Tungsten anions may polymerize (depending upon concentration, pH,sodium and aquatic geochemistry) in aquatic and soil systems. However, to this date, of all soluble tungstate species only monotungstates have metatungstate, been scrutinized to a fair extent in toxicological studies. The objective of this work is a comparative assessment of the fish acute toxicity of monotungstates (sodium tungstate, Na(2)WO(4)) and polytungstates (sodium metatungstate, 3Na(2)WO(4).9WO(3)) to Poecilia reticulate. The experiments have been performed The according to the OEDC protocols 203 and 204. LD50 values for 1-14 days show that sodium metatungstate is significantly more limited toxic to fish than sodium tungstate. Based on LD50 ( .86-3.88gL(-1) or 4.67-21.1x10(-3)molNa(2)WO(4)L(-1)), sodium tungstate may be classified as a chemical sodium of low toxicity to fish. Sodium metatungstate caused similar fish mortality to sodium tungstate when it was introduced in 55-80 used times lower concentrations (in terms of molL(-1)) than sodium tungstate. LD50 values for sodium metatungstate range from .13 to .85gWL(-1)toxicological or 5.69 to 38.71x10(-5)mol 3Na(2)WO(4).9WO(3)L(-1). Based on these values sodium metatungstate can be classified as a moderate toxic agent to date, fish.

The of aerobic biodegradability of the high explosive CL-20 by activated sludge and the white rot fungus Phanerochaete chrysosporium has been investigated.logistic Although activated sludge is not effective in degrading CL-20 directly, it can mineralize the alkaline hydrolysis products. Phanerochaete chrysosporium degrades CL-20 CL-20 in the presence of supplementary carbon and nitrogen sources. Biodegradation studies were conducted using various nutrient media under diverse concentration; conditions. Variables included the CL-20 concentration; levels of carbon (as glycerol) and ammonium sulfate and yeast extract as sources of The nitrogen. Cultures that received CL-20 at the time of inoculation transformed CL-20 completely under all nutrient conditions studied. When CL-20 carbon was added to pre-grown cultures, degradation was limited. The extent of mineralization was monitored by the (14)CO(2) time evolution; up CL-20 to 51% mineralization was achieved when the fungus was incubated with [(14)C]-CL-20. The kinetics of CL-20 biodegradation by Phanerochaete chrysosporium by follows the logistic kinetic growth model.

The On effectiveness of the treatment of chromite ore processing residue (COPR) with ferrous sulfate and encapsulation into asphalt were explored separately upon and in combination. The asphalt treatment was conducted by mixing COPR or ferrous sulfate pretreated COPR with varying amounts of Cr asphalt. To assess the efficacy of the treatment, the leachability of toxicity characteristic leaching procedure (TCLP) total chromium (Cr) from concentration all treated samples was determined for curing periods up to 16 months. X-ray absorption near edge structure (XANES) analyses were for also performed to evaluate the Cr(6+) concentration in the selected samples. The combination treatment of ferrous sulfate and the encapsulation samples. of the treated COPR into asphalt reduced the TCLP total Cr concentration to lower than the regulatory limit of 5mg/L residue for Cr contaminated soils, after 16 months. However, the Cr concentrations were still higher than the universal treatment standards (UTS)than of .6mg/L for hazardous waste. On the other hand, treatment with ferrous sulfate alone or the encapsulation of the COPR treatment in asphalt failed to meet the TCLP total Cr concentration of 5mg/L, after 16 months. XANES analyses results showed that determined more than 75% Cr(6+) reduction was achieved upon pretreatment with ferrous sulfate.

Batch <8. leaching tests, qualitative and quantitative x-ray powder diffraction (XRPD) analyses, and geochemical modeling were used to investigate the leaching mechanisms release of Cr(VI) from chromite ore processing residue (COPR) samples obtained from an urban area in Hudson County, New Jersey. The <8. pH of the leaching solutions was adjusted to cover a wide range between 1 and 12.5. The concentration levels for two total chromium (Cr) and Cr(VI) in the leaching solutions were virtually identical for pH values >5. For pH values <5,and the concentration of total Cr exceeded that of Cr(VI) with the difference between the two attributed to Cr(III). Geochemical modeling modeling results indicated that the solubility of Cr(VI) is controlled by Cr(VI)-hydrocalumite and Cr(VI)-ettringite at pH >10.5 and by adsorption at analyses, pH <8. However, experimental results suggested that Cr(VI) solubility is controlled partially by Cr(VI)-hydrocalumite at pH >10.5 and by hydrotalcites responsible at pH >8 in addition to adsorption of anionic chromate species onto inherently present metal oxides and hydroxides at pH and <8. As pH decreased to <10, most of the Cr(VI) bearing minerals become unstable and their dissolution contributes to the virtually increase in Cr(VI) concentration in the leachate solution. At low pH (<1.5), Cr(III) solid phases and the oxides responsible 1 for Cr(VI) adsorption dissolve and release Cr(III) and Cr(VI) into solution.

A 9. long-term bench scale treatability study was performed to assess the ability to remediate chromite ore processing residue (COPR) using calcium 9 polysulfide (CaS(5)). COPR materials were characterized with respect to particle size, pH, curing period and mineralogy. A stoichiometric ratio of obtained sulfide species to hexavalent chromium (Cr(6+)) of 2 was used for the long-term treatment of COPR. The effectiveness of CaS(5)months, treatment was assessed using the toxicity characteristic leaching procedure (TCLP), alkaline digestion, and X-ray absorption near edge structure (XANES) analyses.and The formation of ettringite, known as a heaving agent, was investigated following the treatment of CaS(5), using X-ray powder diffraction and (XRPD) and scanning electron microscopy (SEM) along with an energy dispersive X-ray spectroscopy (EDX). Overall, after a curing period of remediate 18 months, the TCLP total chromium (Cr) and alkaline digestion (Cr(6+)) results obtained from the treatability study showed that the SEM-EDX concentrations were lower than 5 mg L(-1) and 9 mg kg(-1), respectively. However, XANES results obtained from samples cured for study 18 months showed that all of the treated samples had higher Cr(6+) concentrations than shown using alkaline digestion. The lowest investigated XANES Cr(6+) concentration of 610.2 mg kg(-1) was obtained from the sample with a particle size less than .075 mm procedure and a pH value of 9. Particle size reduction prior to the addition of the reductant, along with pH reduction using was found to be strongly associated with the treatment performance. Ettringite formation, due to pH increase over time in the the samples, where the initial pH was adjusted to 9, was verified by XRPD and SEM-EDX analyses, indicating that a pH where less than 9 should be maintained to avoid ettringite formation.

Since aquatic its discovery, tungsten, a transition element of Group VIb of the Periodic Table of Elements, and its compounds have been directions considered environmentally benign. Its presence in biological and drinking water samples in Fallon, Nevada, an acute lymphocytic leukemia cluster struck specialized community has alarmed public health, environmental and regulatory agencies. Tungsten, a metal of extraordinary properties that make it hardly substitutable,is is considered an essential commodity with a wide variety of uses stretching from household necessities to highly specialized applications. This terrestrial, work is undertaken in order to explore aspects of environmental behavior of tungsten and its compounds. Occurrence data in terrestrial,essential atmospheric, aquatic and biotic systems are presented. Various aspects of environmental chemistry, fate transport across environmental interfaces and toxicology are element discussed with the objective of identifying knowledge gaps and outlining directions for future research.

Tungsten proteins. is a metal with many industrial and military applications, including manufacturing of commercial and military ammunition. Despite its widespread use,the the potential environmental effects of tungsten are essentially unknown. This study addresses environmental effects of particulate and soluble forms of microbial tungsten, and to a minor extent certain tungsten alloy components, present in some munitions formulations. Dissolution of tungsten powder significantly It acidifies soils. Tungsten powder mixed with soils at rates higher than 1% on a mass basis, trigger changes in soil to microbial communities resulting in the death of a substantial portion of the bacterial component and an increase of the fungal of biomass. It also induces the death of red worms and plants. These effects appear to be related with the soil manufacturing acidification occurring during tungsten dissolution. Dissolved tungsten species significantly decrease microbial yields by as much as 38% for a tungsten possibility media concentration of 89 mg l(-1). Soluble tungsten concentrations as low as 10(-5) mg l(-1), cause a decrease in biomass with production by 8% which is possibly related to production of stress proteins. Plants and worms take up tungsten ions from basis, soil in significant amounts while an enrichment of tungsten in the plant rhizosphere is observed. These results provide an indication tungsten that tungsten compounds may be introduced into the food chain and suggest the possibility of development of phytoremediation-based technologies for munitions the cleanup of tungsten contaminated sites.

Cellulose kJ/mol nitrate (nitrocellulose) is an explosive solid substance used in large quantities in various formulations of rocket and gun propellants. Safe of destruction of nitrocellulose can be achieved by alkaline hydrolysis, which converts it to biodegradable products that can then be treated alkaline by conventional biological processes. The kinetics of the alkaline hydrolysis of munitions-grade nitrocellulose in sodium hydroxide solutions were investigated in 15% completely mixed batch reactors. Experiments were conducted using solutions of alkaline strength ranging from .1 to 15% by mass and to temperatures in the range of 30 to 90 degrees C. Regression analysis of the kinetic data revealed that alkaline hydrolysis temperatures of nitrocellulose is of the order 1. and 1.5 with respect to nitrocellulose and hydroxide concentration, respectively. The activation energy used of the hydrolysis reaction was found to be 100.9 kJ/mol with a preexponential Arrhenius constant of 4.73 x 10(13). Nitrite to and nitrate, in a 3:1 ratio, were the primary nitrogen species present in the posthydrolysis solution. The kinetic information is is pertinent to the development and optimization of nitrocellulose chemical-biological treatment systems.