Predicted aquatic and human health risks associated with the presence of metals in the Syr Darya and Shardara Reservoir, Kazakhstan.

Due to the decline of the Aral Sea fishery and recent efforts to expand the fisheries sector in Kazakhstan for both local consumption and global export, there is a need to sustain other fisheries in the area, including the Shardara Reservoir, which lies in the Syr Darya basin. Metals are present in the Syr Darya; yet, their impacts on fishery and consumer health remain unclear. Thus, the objectives of this study were to evaluate: 1) the potential impacts of metals on Syr Darya basin fish and 2) the human health risks posed by consumption of Shardara Reservoir fish. The health of the fishery was assessed by comparing surface water metal concentrations to maximum permissible concentrations (MPCs), calculating water quality index (WQI) and degree of contamination (Cd) values, and evaluating gene expression biomarker responses in wild-caught roach (Rutilus rutilus). To assess the risk to consumers, metal concentrations in roach were used to calculate hazard quotients (HQs) and hazard indices (HIs). Water concentrations of Cu, Fe, Mn, Se, Sr and V exceeded MPCs and all sites were classified as highly polluted based upon WQI and Cd values. This, along with site-specific differences in the expression of genes associated with xenobiotic metabolism and oxidative stress in roach, indicates potential risks to the fishery. Though all HQs and HIs were below 1 indicating a lack of significant risk to consumers, Pb levels in roach exceeded MPCs for safe consumption indicating a potential risk. Given the potential risks to the fishery and consumers, the development of pollution monitoring and management programs are warranted. The work presented here provides initial monitoring data that can be used to aid such efforts and also underscores the need to identify environmental stressors that may thwart the anticipated growth of fisheries in this region.

Legacy and current pesticide residues in Syr Darya, Kazakhstan: Contamination status, seasonal variation and preliminary ecological risk assessment.

The Syr Darya is one of two major rivers in Central Asia supplying critical fresh water to the Aral Sea. In spite of the river's importance and agriculturally-intensive history, few studies have provided a modern evaluation of and the occurrence of pesticide residues potential effects to aquatic life. The primary goal of this investigation was to determine seasonal variations in ambient concentrations of modern and legacy pesticides in bottom sediment and water of the Syr Darya in Kazakhstan (KZ) downstream from an agriculturally-intensive watershed in Uzbekistan. Grab samples and passive samplers were used at five remote sampling stations during June 2015 to provide a baseline for ecotoxicological evaluation. Results were compared with samples collected during and after the agricultural growing season. Polar organic chemical integrative samplers (POCIS) were used in June and calibrated for time-weighted average concentrations of current use pesticides. Among legacy chlorinated pesticides measured in grab samples from the river, lindane (γ-HCH) was detected most frequently with the highest concentrations occurring during June. For all the sampling events, residues of lindane (γ-HCH) ranged from 0.014 to 0.24 µg/L detected in water samples, are among the highest concentrations reported for rivers globally. Concentrations of γ-HCH, p,p'-DDE and dieldrin were highest in October when dieldrin concentrations approached 0.4 µg/L. Sources of legacy pesticides may be either illicit upstream use or evidence of previous atmospheric contamination of glacial meltwater. Chronic exposure to these residues may lead to ecological risk to lower order organisms in both the sediment and water column.

Field-scale cleanup of atrazine and cyanazine contaminated soil with a combined chemical-biological approach.

A former agrichemical dealership in western Nebraska was suspected of having contaminated soil. Our objective was to characterize and remediate the contaminated site by a combined chemical-biological approach. This was accomplished by creating contour maps of the on-site contamination, placing the top 60 cm of contaminated soil in windrows and mixing with a mechanical high-speed mixer. Homogenized soil containing both atrazine [6-chloro-N-ethyl-N'-isopropyl-1,3,5-triazine-2,4-diamine] and cyanazine {2-[[4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl] amino]-2-methylpropanenitrile} was then used in laboratory investigations to determine optimum treatments for pesticide destruction. Iron suspension experiments verified that zerovalent iron (Fe(0)) plus ferrous sulfate (FeSO(4).7H(2)O) removed more than 90% of both atrazine and cyanazine within 14 d. Liquid chromatography/mass spectrometry (LC/MS) analysis of the atrazine solution after treating with Fe(0) and ferrous sulfate identified several degradation products commonly associated with biodegradation (i.e., deethlyatrazine (DEA), deisopropylatrazine (DIA), hydroxyatrazine (HA), and ammelines). Biological treatment evaluated emulsified soybean [Glycine max (L.) Merr.] oil (EOS) as a carbon source to stimulate biodegradation in static soil microcosms. Combining emulsified soybean oil with the chemical amendments resulted in higher destruction efficiencies (80-85%) and reduced the percentage of FeSO(4) needed. This chemical-biological treatment (Fe(0) + FeSO(4) + EOS, EOS Remediation, Raleigh, NC) was then applied with water to 275 m(3) of contaminated soil in the field. Windrows were tightly covered with clear plastic to increase soil temperature and maintain soil water content. Temporal sampling (0-342 d) revealed atrazine and cyanazine concentrations decreased by 79 to 91%. These results provide evidence that a combined chemical-biological approach can be used for on-site, field-scale treatment of pesticide-contaminated soil.

Remediating dinoseb-contaminated soil with zerovalent iron.

Dinoseb, a dinitroherbicide, was once commonly used in aerial crop dusting of agronomic crops in the western United States. Widespread use combined with improper disposal practices at rural air strips has contaminated numerous sites. Our objective was to determine if zerovalent iron (Fe(0)) could remediate dinoseb-contaminated soil. This was accomplished by conducting a series of batch experiments where we first determined if Fe(0) could remove dinoseb in aqueous solutions, then in contaminated soil slurries, and finally, in unsaturated soil microcosms (25 degrees C, theta(g)=0.30 kg H(2)O kg(-1)). Results showed quantitative dinoseb removal in the presence of Fe(0) in all three media (aqueous solutions, soil slurries, moist soils) and that removal increased by including either ferrous or aluminum sulfate with the iron treatment. Incubating contaminated soils with Fe(0) or Fe(0) plus salts (FeSO(4) or Al(2)(SO(4))(3)) resulted in 100% removal of dinoseb within 7 d. Liquid chromatography/mass spectrometry (LC/MS) analysis of degradation products showed the transformations imposed by the iron treatments were reduction of one or both nitro groups to amino groups. These amino degradation products were further transformed to quinonimine and benzoquinone and did not persist. These results support the use of zerovalent iron for on-site treatment of dinoseb-contaminated soil.

Remediating RDX-contaminated ground water with permanganate: laboratory investigations for the Pantex perched aquifer.

Ground water beneath the U.S. Department of Energy Pantex Plant is contaminated with the high explosive RDX (hexahydro-1,3,5-trinitro-1,3,5 triazine). The USDOE Innovative Treatment and Remediation Demonstration (ITRD) program identified in situ oxidation by permanganate as a technology fit for further investigation. We evaluated the efficacy of KMnO(4) to transform and mineralize RDX by determining degradation kinetics and carbon mass balances using (14)C-RDX. Aqueous RDX solutions (2-5 mg L(-1)) and RDX-contaminated slurries (50% solids, w/v) were treated with KMnO(4) at 1000, 2000, 4000, and 20000 mg L(-1). Treating an aqueous RDX solution of 2.8 mg L(-1) with 20000 mg KMnO(4) L(-1) decreased RDX to 0.1 mg L(-1) within 11 d while cumulative mineralization proceeded for 14 d until 87% of the labeled carbon was trapped as (14)CO(2). Similar cumulative mineralization was obtained when Pantex aquifer material was included in the solution matrix. Other experiments using 4000 mg KMnO(4) L(-1) showed that initial RDX concentrations (1.3-10.4 mg L(-1)) or initial pH (4-11) had little effect on reaction rates. Attempts to identify RDX degradates and reaction products showed that N(2)O was a product of permanganate oxidation and constituted 20 to 30% of the N balance. Time-course measurements of a (14)C-RDX solution treated with KMnO(4) revealed few (14)C-labeled degradates but through liquid chromatography-mass spectrometry (LC-MS) analysis, we present evidence that 4-nitro-2,4-diaza-butanol is formed. Aquifer microcosm studies confirmed that the transformation products not mineralized by KMnO(4) were much more biodegradable than parent RDX. These results indicate permanganate can effectively transform and mineralize RDX in the presence of aquifer material and support its use as an in situ chemical oxidation treatment for the Pantex perched aquifer.

Analysis of oxytetracycline, tetracycline, and chlortetracycline in water using solid-phase extraction and liquid chromatography-tandem mass spectrometry.

A method using liquid chromatography-tandem mass spectrometry has been developed for determination of trace levels of tetracycline antibiotics in ground water and confined animal feeding operation waste water. Oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) were extracted from water samples using both polymeric and C18 extraction cartridges. The addition of a buffer containing potassium phosphate and citric acid improved tetracycline recoveries in lagoon water. Method detection limits determined in reagent water fortified with 1 microg l(-1) OTC, TC, and CTC were 0.21, 0.20, and 0.28 microg l(-1). Method detection limits in lagoon water samples fortified at 20 microg l(-1) for OTC, TC, and CTC were 3.6, 3.1, and 3.8 microg l(-1). Variability in recovery from laboratory fortified blanks ranged from 86 to 110% during routine analysis.

Trace analysis of ethanol, MTBE, and related oxygenate compounds in water using solid-phase microextraction and gas chromatography/mass spectrometry.

Solid-phase microextraction (SPME) and gas chromatography/mass spectrometry have been combined for trace-level determination of very polar compounds in water, including the widely used gasoline oxygenates ethanol and methyl tert-butyl ether (MTBE). A relatively simple extraction method using a divinylbenzene/Carboxen/poly(dimethylsiloxane) SPME fiber was optimized for the routine analysis of ethanol and MTBE in groundwater and reagent water. A sodium chloride concentration of 25% (w/w) combined with an extraction time of 25 min provided the greatest sensitivity while maintaining analytical efficiency. Replicate analyses in fortified reagent and groundwater spiked with microgram per liter concentrations of ethanol and MTBE indicate quantitative and reproducible recovery of these and related oxygenate compounds. Method detection limits were 15 microg L(-1) for ethanol, 1.8 microg L(-1) for tert-butyl alcohol, 0.038 microg L(-1) for tert-amyl methyl ether, 0.025 microg L(-1) for ethyl-tert-butyl ether, and 0.008 microg L(-1) for MTBE.

Sensitive determination of RDX, nitroso-RDX metabolites, and other munitions in ground water by solid-phase extraction and isotope dilution liquid chromatography-atmospheric pressure electro-spray [correction of chemical] ionization mass spectrometry.

Recent improvements in the LC-MS interface have increased the sensitivity and selectivity of this instrument in the analysis of polar and thermally-labile aqueous constituents. Determination of RDX, nitroso-RDX metabolites, and other munitions was enhanced using LC-MS with solid-phase extraction, 15N3-RDX internal standard, and electrospray ionization (ESI) in negative ion mode. ESI produced a five-fold increase in detector response over atmospheric pressure chemical ionization (APCI) for the nitramine compounds, while the more energetic APCI produced more than twenty times the ESI response for nitroaromatics. Method detection limits in ESI for nitramines varied from 0.03 microgram l-1 for MNX to 0.05 microgram l-1 for RDX.