Effect of zero-valent iron and a redox mediator on removal of selenium in agricultural drainage water.

Effective and economical removal of selenium (Se) in agricultural drainage water is very important in Se bioremediation. Zero-valent iron (ZVI) and a redox mediator [anthraquinone-2,6-disulfonate (AQDS)] were assessed for their ability to enhance the removal of Se(VI) or Se(IV) (500 microg/L) in synthetic drainage water by Enterobacter taylorae. The results showed that E.

Soil enzyme activities of long-term reclaimed wastewater-irrigated soils.

Studies have shown that physical and chemical properties of soils may be significantly changed when they are subjected to long-term reclaimed water irrigation. It remains unclear how reclaimed water application may affect nutrient cycling in soils. Soil enzymes are responsible for the biogeochemical cycling of many elements and are more sensitive indicators of the ecological changes.

Application of redox mediator to accelerate selenate reduction to elemental selenium by Enterobacter taylorae.

Acceleration of bacterial reduction of selenate [Se(VI)] to insoluble elemental Se [Se(0)] plays an important role in Se bioremediation. Anthraquinone-2,6-disulfonate (AQDS), a redox mediator, was assessed for its ability to enhance the reduction of Se(VI) (2000 microg/L) to Se(0) by Enterobacter taylorae in various media. The results showed that addition of AQDS did not increase Se(VI) reduction in the media containing 50 and 250 mg/L yeast extract, suggesting that E.

Bacterial reduction of selenate to elemental selenium utilizing molasses as a carbon source.

Selecting an inexpensive and effective organic carbon source is the key to reducing the cost in selenium (Se) remediation. Five bacteria were screened based on their ability in using molasses as an organic carbon source to reduce selenate [Se(VI)] in drainage water. Efficiency of Se removal differed in the molasses-added drainage water containing different bacteria, with an order of Enterobacter taylorae>Pantoea sp.

Simultaneous removal of chlorothalonil and nitrate by Bacillus cereus strain NS1.

Elevated NO3- and chlorothalonil (CTN) have been found in production nursery recycling ponds. Bacillus cereus strain NS1 isolated from nursery recycling pond sediment was assessed for its ability to reduce NO3- and degrade CTN in a mineral medium. The results showed that the efficiency of NO3- reduction and CTN degradation by B.

Supplementing Bacillus sp. RS1 with Dechloromonas sp. HZ for enhancing selenate reduction in agricultural drainage water.

Cost and efficiency are two important factors considered in the remediation of Se-contaminated agricultural drainage water through bacterial reduction of soluble Se(VI) to insoluble Se(0). Bacillus sp. RS1 isolated from rice straw was assessed for its ability to use inexpensive molasses to reduce Se(VI) in agricultural drainage water containing NO3- levels of 0, 50, 100, 250, and 500 mg/L.

Development of a perchlorate reductase-based biosensor for real time analysis of perchlorate in water.

Perchlorate (ClO4-) contamination of ground water is a widespread problem in the U.S., which can adversely affect human health and wildlife.

Removal of selenate in river and drainage waters by Citrobacter braakii enhanced with zero-valent iron.

A cost-effective remediation method is needed to remove selenium (Se) from Se-contaminated water. In this study, a selenate [Se(VI)]-reducing bacterium, Citrobacter braakii, that is capable of using molasses as a carbon source to reduce Se(VI) from natural river and drainage waters was isolated. During an 8-day experiment, 87-97% of the added Se(VI) in New River water and White River water, California, was reduced to elemental Se [Se(0)] or transformed to organic Se.

Characterization of sediment bacteria involved in selenium reduction.

Bacterial reduction of selenium (Se) oxyanions (Se[VI] and Se[IV]) to elemental Se (Se[0]) is one of the major biogeochemical processes removing Se from agricultural drainage water and depositing Se in the sediment. This study was conducted to characterize Se-reducing bacterial populations in Lost Hills evaporation pond sediment and to observe their response to Se(VI) and organic C amendments. Se(VI) was removed from the dissolved phase in the sediment slurries amended with organic C with a decrease in redox potential (Eh).

Effect of arsenate and molybdate on removal of selenate from an aqueous solution by zero-valent iron.

Zero-valent iron (ZVI) is an inexpensive agent that can remove many common environmental contaminants. We investigated the effects of arsenate [As(V)] and molybdate [Mo(VI)] on the removal of selenate [Se(VI)] (1000 microg/L) in a 5 mM Cl- and SO4(2-) solution by ZVI. Analysis of selenium (Se) species in a control experiment revealed that there was no detectable selenite [Se(IV)] in the solution and Se(IV) was the only dominant form of Se in the PO(4)3- extract, revealing that the removal of Se(VI) by ZVI appeared to be partly attributed to the reduction of Se(VI) to Se(IV) by Fe(II) oxidized from ZVI, followed by rapid adsorption of Se(IV) to Fe oxyhydroxes (Fe(OH)).

Use of starch and potato peel waste for perchlorate bioreduction in water.

The cost of carbon substrates for microbial reduction of perchlorate (ClO(4)(-)) is central to the success and competitiveness of a sustainable bioremediation strategy for ClO(4)(-). This study explored the potential application of starch in combination with an amylolytic bacterial consortia and potato peel waste for ClO(4)(-) bioreduction. We obtained a potent amylolytic bacterial consortium that consisted of a Citrobacter sp.

Diversity of biosurfactant producing microorganisms isolated from soils contaminated with diesel oil.

Biosurfactant production is a desirable property of hydrocarbon-degrading microorganisms (HDM). We characterized biosurfactant producing microbial populations from a Long Beach soil, California (USA) and a Hong Kong soil (China), contaminated with diesel oil. A total of 33 hydrocarbon-utilizing microorganisms were isolated from the soils.

Removal of selenium from river water by a microbial community enhanced with Enterobacter taylorae in organic carbon coated sand columns.

Discovering an effective means to remove selenium (Se) from Se-contaminated water is fundamental in minimizing environmental contamination and ensuring wildlife protection. In this study, Enterobacter taylorae attached to tryptic soy agar (TSA) coatings was used in sand columns to remove Se from a natural river water. During 80 days of the experiment, E.

Removal of selenate from water by zerovalent iron.

Zerovalent iron (ZVI) has been widely used in the removal of environmental contaminants from water. In this study, ZVI was used to remove selenate [Se(VI)] at a level of 1000 microg L(-1) in the presence of varying concentrations of Cl-, SO(2-)4, NO(-)3, HCO(-)3, and PO(3-)4. Results showed that Se(VI) was rapidly removed during the corrosion of ZVI to iron oxyhydroxides (Fe(OH)).

Comparative bioremediation of soils contaminated with diesel oil by natural attenuation, biostimulation and bioaugmentation.

Bioremediation of diesel oil in soil can occur by natural attenuation, or treated by biostimulation or bioaugmentation. In this study we evaluated all three technologies on the degradation of total petroleum hydrocarbons (TPH) in soil. In addition, the number of diesel-degrading microorganisms present and microbial activity as indexed by the dehydrogenase assay were monitored.

Illicit use of prescribed stimulant medication among college students.

The authors investigated illicit use of stimulant medications at a midwestern university. They used a questionnaire to (a) examine the extent to which university students illicitly used stimulant medications prescribed for attention-deficit hyperactivity disorder; (b) determine why college students abused such drugs; and (c) identify the factors that predicted illicit use of prescribed stimulant medication. Findings revealed that 17% of 179 surveyed men and 11% of 202 women reported illicit use of prescribed stimulant medication.

Bacterial diversity in selenium reduction of agricultural drainage water amended with rice straw.

Bacterial reduction of the Se oxyanions selenate [Se(VI)] and selenite [Se(IV)] to elemental selenium [Se0] is an important biological process in removing Se from drainage water. This study was conducted to characterize the molecular diversity of bacterial populations involved in Se reduction of drainage water amended with rice (Oryza sativa L.) straw and also to monitor the bacterial community shifts during the course of the study.

Effects of information on college students' perceptions of antidepressant medication.

The authors examined the impact of pharmaceutical companies' advertisements on college students' perceptions of depression and concomitant treatment with antidepressants among 13 male and 31 female undergraduates from a midwestern university. The students were randomly assigned to groups that read either pharmaceutical company advertisements or scientific information about depression and its treatment. The analysis revealed that 40% of the women in the advertisement condition as opposed to 1 woman (6%) in the scientific condition rated themselves as having mild, moderate, or severe depression on the Beck Depression Inventory, second edition.

Fate of colloidal-particulate elemental selenium in aquatic systems.

Bacterial reduction of selenate [Se(VI)] to elemental Se [Se(0)] is considered an effective bioremediation technique to remove selenium (Se) from agricultural drainage water. However, the fate of the newly formed Se(0) in aquatic systems is not known when it flows out of the treatment system. A set of laboratory experiments was conducted to determine the fate of the colloidal-particulate Se(0) in a water column and in a water-sediment system.

Selenate reduction in river water by Citerobacter freundii isolated from a selenium-contaminated sediment.

Bacterial reduction of selenate [Se(VI)] to insoluble elemental Se [Se(0)] is an important remedial technology to remove selenium (Se) from Se-impacted water. Citerobacter freundii, a Se(VI) reducer, isolated from a Se-contaminated sediment was assessed for its ability to reduce Se(VI) in a mineral culture medium and natural river water in a series of laboratory batch experiments. The results showed that a combination of yeast extract and glucose used in the culture medium was more effective than yeast extract alone, yeast extract plus sodium acetate, and yeast extract plus sodium lactate for reduction of Se(VI) to Se(0) by C.

Molecular analysis of a perchlorate reductase from a perchlorate-respiring bacterium Perc1ace.

Perchlorate (ClO4-) is a major ground water pollutant of public health concern. ClO4- reductase is the key enzyme in the pathway of ClO4- breakdown. ClO4- reductase from cell-free extracts of the ClO4- -respiring bacterium perc lace was purified 10-fold by ion-exchange and molecular exclusion fast protein liquid chromatography (FPLC).

Biodegradation kinetics of endosulfan by Fusarium ventricosum and a Pandoraea species.

Endosulfan, classified as an organochlorine pesticide, is rated by the U.S. EPA as a Category 1 pesticide with extremely high acute toxicity.

Factors affecting reduction of selenate to elemental selenium in agricultural drainage water by Enterobacter taylorae.

Microbial reduction of selenate [Se(VI)] to elemental selenium [Se(0)] is a useful technique for removing Se from agricultural drainage water. A series of batch experiments were conducted in the laboratory to determine the effects of yeast extract (50-1000 mg/L), salinity (EC, 5-75 dS/m), and NO(3)(-) (5-100 mg/L) on the removal of Se(VI) (2000 microg/L) from drainage water by Enterobacter taylorae. Results showed that relatively high amounts of yeast extract (500 mg/L) were needed for E.

Removal of selenate in simulated agricultural drainage water by a rice straw bioreactor channel system.

Removal of selenium (Se) from agricultural drainage water is important in protecting wetland wildlife. Three flow-through bioreactor channel systems (BCSs), each with three channels filled with rice (Oryza sativa L.) straw, were set in the laboratory to determine removal of selenate [Se(VI)] (1020 microg L(-1)) from drainage water with a salinity of 10.

Effects of mercury on microbial biomass and enzyme activities in soil.

Mercury (Hg) is a persistent soil pollutant that affects soil microbial activity. We monitored the changes in soil microbial biomass and activity of enzymes, including alkaline phosphatase, arylsulfatase, fluorescein diacetate (FDA) hydrolytic activity, and o-diphenol oxidase (o-DPO) in three soils contaminated with different concentrations of Hg. Increasing levels of Hg, from 0.