The Influence of Organic Matter and pH on DDT Aqueous Solubility

We have studied the concentrations of DDT in ground water samples at field locations with DDT-polluted topsoil and concentrations and solubility in samples prepared from deionized water with different types and concentration of organic acids. The solubility of DDT increased with increasing concentration of humic acid when the pH of the samples was low (adjusted to about 5.5). The effect flutters in the humic acid concentration range from 200 to 300?mg/L, in accordance with humic acid hydrophobicity, operationally measured as liquid surface tension. The findings correspond to trends previously reported in the literature. The trend of increasing solubility was not found using fulvic acid or low-molecular-weight aliphatic acids. No trend was found adding humic acid without adjusting the pH. The mechanism of enhanced solubility due to humic compounds can explain relatively high levels of DDT in ground water. The ground water samples, however, had a moderately high concentration of maximum 6?µg/L compared with a maximum of about 2300?µg/L in the water samples with humic acid in pure water.     

Induction of non-protein thiols and phytochelatins by cadmium in Eichhornia crassipes

Abstract

Impact of root Cd concentration on production of cysteine, non-protein thiols (NP-SH), glutathione (GSH), reduced glutathione (GSSG), and phytochelatins (PCs) in Eichhornia crassipes exposed to different dilutions of brass and electroplating industry effluent (25%, 50%, and 75%), and synthetic metal solutions of Cd alone (1, 2.5, and 3.5?ppm) and with Cr (1?ppm Cd + 1?ppm Cr, 2.5?ppm Cd + 3?ppm Cr, and 3.5?ppm Cd + 4?ppm Cr) was assessed in a 45?days study. Different treatments were used to understand and compare differential antioxidant defense response of plant under practical drainage (effluent) and experimental synthetic solutions. The production of NP-SH and cysteine was maximum under 2.5?ppm Cd + 3?ppm Cr treatments i.e., 1.78?µmol/g fw and 288?nmol/g fw, respectively. The content of GSH declined whereas that of GSSG increased progressively with exposure duration in all treatments. HPLC chromatograms revealed that the concentrations of PC2, PC3, and PC4 (248, 250, and 288?nmol-SH equiv.g^?1 fw, respectively) were maximum under 1?ppm Cd, 1?ppm Cd + 1?ppm Cr, and 2.5?ppm Cd + 3?ppm Cr treatments, respectively. PC2, PC3, and PC4 concentrations increased with Cd accumulation in the range 812–1354?µg/g dry wt, 1354–2032?µg/g dry wt and 2032–3200?µg/g dry wt, respectively. Thus, the study establishes a direct proportionality relationship between concentration/length of phytochelatins and root Cd concentrations, upto threshold limits, in E. crassipes.     

Monte Carlo Vadose Zone Model for Soil Remedial Criteria

Many vadose zone models are available for environmental remediation, but few offer the procedures for verifying model predictions with field data and for dealing with uncertainties associated with model input parameters. This article presents a modified model combining a one-dimensional vadose-zone transport model and a simple groundwater mixing model with a function of Monte Carlo simulation (MCS). The modified model is applied to determine soil remedial concentrations for methyl tertiary butyl ether (MTBE). The modified model generates a distribution of MTBE ground-water concentrations at the point of compliance. This distribution can be used to estimate the risk of exceeding groundwater quality standard given soil remedial concentrations. In a case study, soil remedial concentration for MTBE is established to be 5?µg/kg, with a 95% and 10?µg/kg with a 50% probability that groundwater concentration will not exceed the water quality objective of 13?µg/L. Furthermore, this study uses MCS to investigate uncertainties of model input parameter hydraulic conductivity (K). One set of data (K1) is based on the results of hydraulic conductivity laboratory tests, and the other (K2) is based on the results of slug tests conducted in the field. As expected, the laboratory data show smaller K values than the field data. The comparison of the MCS results obtained from the two sets of K data indicates that the MTBE groundwater concentrations calculated based on K1 are generally 160 to 625% greater than those calculated based on K2 at the same percentiles of the MCS distribution. A higher soil remedial concentration of9jig/kg is then calculated based on the MCS results from K2 at 95%ile and 19?µg/kg at 50%ile.     

Longitudinal Exposure to Selected Pesticides in Drinking Water

The presence and temporal fluctuations of concentrations of insecticides and herbicides in natural waters has been well documented. Little, however, is known about exposure to pesticides through drinking water for the general population. Concentrations often pesticides, including 4,4′DDE and atrazine, were measured up to six times at equally spaced intervals over a 1-year period in drinking water of 80 randomly selected residences in Maryland. Atrazine was detected in 228 (57.9%) of the drinking water samples with a mean of 0.15?µg/L, with standard deviation 0.12?µg/L, median 0.17?µg/L, and range <0.037 to 0.46?µg/L. 4,4′DDE was found in 22 (5.6%) water samples; no other target analytes were detected. Concentrations of atrazine in drinking water were found to vary over a 12-month period with the greatest concentrations in the late summer and fall and the lowest in the early spring. Atrazine concentrations in drinking water were influenced more by differences in levels among residences than by time of year. Seven-day average exposures and exposures per unit body weight to atrazine in drinking water exhibited a similar temporal pattern. Among individuals, drinking water consumption rate was a more important determinant of atrazine exposure (µg/d) and exposure per unit body weight (µg/kg/d) than atrazine concentration in drinking water or body weight.     

Biosorption of lead by cotton shells powder: Characterization and equilibrium modeling study

Lead (Pb) is a toxic heavy metal causing serious health risks to humans and animals. In the present study, cotton (Gossypium hirsutum L.) shells powder was used as adsorbent for the treatment of synthetic Pb-contaminated water. The batch scale biosorption capacity of cotton shells powder was evaluated to study the effects of Pb concentrations, adsorbent doses and contact time at constant pH (6) and temperature (25?°C). Results revealed that sorption of Pb increased (q?=?0.09–9.60?mg/g) with increasing Pb concentration (1–15?mg/L) and contact time (15–90?min) while decreasing adsorbent dose (1–0.1?g/100?mL). The maximum Pb removal (90%) was achieved at Pb concentration (1?mg/L), contact time (90?min) and adsorbent dose (1?g/100?mL). Freundlich isotherm model proved best fit for Pb sorption (R²?=?0.99). The cotton shells powder has microporous structure confirmed by SEM, and has BET surface area (45 m²/g) and pore size (2.3 µm). These surface moieties along with various functional groups (C-H, C-O, C=O, O-H, S=O) confirmed by FTIR analysis might involve in Pb removal by complexation and ion exchange mechanisms. The cotton shells powder biomass could be considered as promising adsorbent for the removal of Pb from contaminated water.     

Platinum cytotoxic drugs in the municipal wastewater and drinking water,a validation method and health risk assessment

Three cancerostatic platinum compounds (CPCs) including cisplatin, carboplatin and oxaliplatin are complexes of Pt and classified as probable carcinogenic compounds to humans. This study aimed to perform health risk assessment of platinum cytotoxic drugs for drinking water by developing a sensitive analytical method in the water resource of Qom Province in the central part of Iran. Concentrations of the platinum drugs were determined, including 052 ± 0.2 µg/L for cisplatin, 0.94 ± 0.36 µg/L for carboplatin and 0.27 ± 0.16 µg/L for oxaliplatin in influent samples, and 0.24 ± 0.07 µg/L for cisplatin, 0.28 ± 0.05 µg/L for carboplatin and 0.11 ± 0.01 µg/L for oxaliplatin in effluent samples. The results indicated that in all the well water samples related to the groundwater, the concentration of the platinum-based compounds was lower than the calculated limits of quantification (LOQ); the concentration of cisplatin, carboplatin and oxaliplatin across the samples in the station of drinking water distribution was also below the limits of detection (LOD). The resulting margin of exposure (MOE) is lower than one (MOE < 1) for the three groups including children, pregnant women and lactation women related to cisplatin and carboplatin was determined through exposure to raw and untreated drinking water. Further research is recommended to be conducted in this area, particularly environmental fate of metabolites and transformation products.     

Electrophysiological and behavioral responses of Asian and European honeybees to pear flower volatiles

Honeybee pollination behavior is influenced by flower volatiles, which honeybees sense via olfactory receptors. Honeybees are only weakly attracted to pear flowers. To investigate the potential reasons, we extracted and determined the floral volatile compounds from three pear cultivars (Su, Ya, and Xuehua) using headspace solid-phase micro-extraction (HS-SPME) and gas chromatography-mass spectrometry (GC–MS). The effects of pear flower volatiles on the Asian honeybee (Apis cerana cerana Fabricius) and the European honeybee (Apis mellifera ligustica Spinola) were determined by electroantennogram (EAG) assays and behavioral tests in a three-arm olfactometer. Among the 76 flower volatiles detected with GC–MS, 21 were found in all three pear cultivars, accounting for approximately 70% of the total volatile content. 3-Methyl-1-butanol and (+)-limonene volatiles had the highest relative content. Five compounds elicited strong EAG responses in both bee species: 2-methylbutyraldehyde, 1-nonanal, 6-methyl-5-hepten-2-one, 3-methyl-1-butanol, and (+)-limonene. Neither bee species showed positive taxis to these volatiles. In behavioral tests, A. mellifera ligustica showed a low preference for 6-methyl-5-hepten-2-one (20%, 400 µg/µL) and 2-phenethyl alcohol (16.7%, 400 µg/µL). Apis cerana cerana showed a low preference for 6-methyl-5-hepten-2-one (6.7%, 400 µg/µL) and 1-nonanal (10%, 400 µg/µL), whereas its preferences for 3-methyl-1-butanol (43.3%, 400 µg/µL) and α-farnesene (40%, 400 µg/µL) were similar to that for the control. Therefore, a lack of attractive volatile compounds could explain why honeybees are only weakly attracted to pear flowers. Therefore, to achieve acceptable pollination in pear orchards, we suggest using flower-scent sugar syrup feeding and a saturation pollination strategy.     

Cadmium and zinc uptake,growth, and primary production inCoscinodiscus granii cultures containing low levels of cells and dissolved organic carbon

Coscinodiscus granii Gough was cultivated at low cell densities in aged Atlantic sea water containing very little dissolved organic carbon; the water was enriched with low levels of nutrients but no chelators were added. Cadmium additions provided final concentrations of 0.1 to 26.5 μg Cd l⁻¹, zinc being kept constant at a level of 38 μg Zn l⁻¹. Carrier-free¹⁰⁹Cd and⁶⁵Zn were used as tracers for the two metals. Growth in terms of cell numbers and primary productivity capacity, using the¹⁴C uptake rate, was followed during the exponential growth phase for the first 5 days of the experiment and then for a further 3 days during the stationary phase. On each day, the metal contents of the cells were determined. Cadmium concentrations of 20 μg Cd l⁻¹ and more resulted in growth inhibition whereas 17.5 μg Cd l⁻¹ reduced the growth only slightly. The physiological state of the cells influenced the heavy-metal uptake per cell at sublethal Cd levels. Dead cells had a higher heavy-metal concentration than living cells. Microscopical observations revealed that cells just about to divide were less sensitive to a given toxic heavy-metal concentration than cells which had recently divided. This might have been due to different surface/volume ratios.     

The Effect of Groundwater Aeration on PCE Natural Attenuation Patterns

Attempts to remediate ground water contaminated with tetrachloroethylene at a Superfund site in Minnesota included the installation of a vacuum vaporizer well. Prior to the remedial system installation, the contaminant source half-life was approximately 0.3 years. Aquifer aeration by the vacuum vaporizer well unintentionally disrupted the ambient natural attenuation rate. Although the overall plume size did not increase, concentrations of the anaerobic breakdown products of tetrachloroethylene—trichloroethylene, cis-dichloroethylene, and vinyl chloride—all increased in downgradient monitoring wells after startup of the vacuum vaporizer well. At a well 360 feet downgradient of the source, trichloroethylene increased from concentrations below 10?µg/L to over 35?µg/L, while cis-dichloroethylene concentrations increased from 70?µg/L to 370?µg/L. Vinyl chloride, which was below detection limits at this location prior to operation of the vacuum vaporizor well, increased in concentration to 83?µg/L. Concentrations of these contaminants returned to pre-sparging levels after deactivation of the system, indicating that existing anaerobic natural attenuation processes play an important role in the remediation of ground water at this site. Investigations should routinely assess the role of natural attenuation in remediation before implementing engineered remedies that may disrupt existing beneficial attenuation processes.     

Determination of subnanomolar concentrations of vanadium in environmental water samples using flow injection with luminol chemiluminescence detection

A flow injection chemiluminescence method is described for the determination of subnanomolar concentrations of vanadium in environmental water samples. The procedure is based on the oxidation of luminol in the presence of dissolved oxygen catalyzed by vanadium(IV). Vanadium(V) reduction and preconcentration of vanadium(IV) was carried out using in‐line silver reductor and 8‐hydroxyquinoline chelating columns at pH 3.15, respectively. The calibration graph for vanadium(IV) was linear in the concentration range of 0.025–10 µg/L with relative standard deviation in the range of 0.4–5.58%. The detection limit (3s blank) was 3.8 × 10^?3 µg/L without preconcentration; when the vanadium(IV) was preconcentrated with an 8‐HQ column for 1 min (2.0 mL of sample loaded), the detection limit of 5.1 × 10^?4 µg/L was achieved. One analytical cycle can be completed in 2.0 min. The analysis of certified reference materials (CASS‐4, NASS‐5 and SLRS‐4) by the proposed method showed good agreement with the certified values. The method was successfully applied to the determination of total dissolved vanadium in environmental water samples. Copyright © 2010 John Wiley & Sons, Ltd.     

Comparison of Four Species Sensitivity Distribution Methods to Calculate Predicted No Effect Concentrations for Bisphenol A

Bisphenol A (BPA, CAS RN 80-05-7) is a high production volume chemical used as an intermediate in the production of polycarbonate plastic and epoxy resins. During its manufacture and use, some emissions to surface waters are anticipated. Chronic predicted no effect concentrations (PNECs) for aquatic systems are used to support the assessment of potential risks to aquatic organisms in receiving waters. PNECs for a compound are considered protective of populations, communities, and ecosystems. Traditionally, PNECs are derived by taking the lowest no-observed effect concentration (NOEC) from a set of toxicity studies and dividing by an assessment factor (e.g., 10 to 1000). This traditional approach is appropriate for substances with few data, but may not be necessary for substances with many valid studies. For well-studied substances, statistical approaches (i.e., development of Species Sensitivity Distribution or SSD methods) can be used to calculate a PNEC that makes use of the full distribution of available NOEC values. Bisphenol A has an extensive set of aquatic toxicity studies covering diverse taxa including algae, hydra, rotifers, mollusks, crustaceans (both benthic and pelagic), insects, annelids, fish, and amphibians. The full chronic data set was used to calculate PNEC values using four SSD methods: (1) the Hazard Concentration (HC5) approach developed by The Netherlands National Institute of Public Health and the Environment (RIVM), (2) the U.S. Environmental Protection Agency's water quality criteria procedure, (3) SigmaPlot (Systat 2000) commercial software that calculates percentile values, and (4) a distributional method consistent with that used by Environment Canada. Using these approaches, PNEC values for BPA range from 11 to 71 μ g/L. Literature studies suggest that application of an additional assessment factor is unwarranted if an SSD-based PNEC is based on chronic data. SSD-derived PNEC values and the traditionally derived PNEC value of 1.6 μ g/L are then compared to concentrations of BPA that have been measured in North American and European surface waters. Adverse risks to aquatic organisms are not anticipated from measured concentrations of BPA in North American and European surface waters.     

Enhancement of extracellular bispecific anti‐MUC1 nanobody expression in E. coli BL21 (DE3) by optimization of temperature and carbon sources through an autoinduction condition

Escherichia coli is one of the most suitable hosts for production of antibodies and antibody fragments. Antibody fragment secretion to the culture medium improves product purity in cell culture and diminishes downstream costs. In this study, E. coli strain BL21 (DE3) harboring gene encoding bispecific anti‐MUC1 nanobody was selected, and the autoinduction methodology for expression of bispecific anti‐MUC1 nanobody was investigated. Due to the replacement of IPTG by lactose as inducer, less impurity and toxicity in the final product were observed. To increase both intracellular and extracellular nanobody production, initially, the experiments were performed for the key factors including temperature and duration of protein expression. The highest amount of nanobody was produced after 21 h at 33°C. The effect of different carbon sources, glycerol, glucose, lactose, and glycine as a medium additive at optimum temperature and time were also assessed by using response surface methodology. The optimized concentrations of carbon sources were obtained as 0.75% (w/v), 0.03% (w/v), 0.1% (w/v), and 0.75% (w/v) for glycerol, glucose, lactose, and glycine, respectively. Finally, the production of nanobody in 2 L fermenter under the optimized autoinduction conditions was evaluated. The results show that the total titer of 87.66 µg/mL anti‐MUC1 nanobody, which is approximately seven times more than the total titer of nanobody produced in LB culture medium, is 12.23 µg/L .     

Bioaccumulation of heavy metals in tissues of selected fish species from Ganga river,India, and risk assessment for human health

The study measured the concentration of Cd, Cr, Pb, Cu, and Zn in various fish tissues (muscle, gills, and liver) of 18 fish species (C. gachua, C. marulius, C. punctatus, C. nama, C. ranga, H. fossilis, C. batrachus, P. ticto, P. phutunio, L. rohita, L. calbasu, L. gonius, T. putitora, T. tor, R. rita, G. chapra, H. ilisa, and N. botia) collected from Ganga river. It is the survey regarding metal concentration in fish tissues increasing day by day. The metal concentration in different fish tissues varied on the following range: Cu (0.45–8.54 µg/g wet wt), Zn (0.07–2.2 µg/g wet wt), Pb (0.20–2.62 µg/g wet wt), Cd (0.07–2.32 µg/g wet wt), and Cr (0.09–1.74 µg/g wet wt). The results show the concentration of Pb, Cd, and Cr metals to be higher than internationally recommended standard limits (as determined by the WHO and FAO) and other similar studies. Generally, higher concentrations of metals were found in liver and gills than muscles. Despite lower estimated daily intake (EDI) of fish in the area (per recommended daily allowance guidelines), values of daily average consumption were lower than the recommended values by FAO/WHO/EFSA, and in fish samples these were below the provisional permissible levels for human consumption. The continuous exposure to heavy metals has been linked to the development of mental retardation, kidney damage, various cancers, and even death in instances of very high exposure in human body.     

Effect of Food Concentration Inside Eelgrass Beds on the Energy Balance of the Invasive Mussel Musculista Senhousia

Samples of Musculista senhousia, 20 mm in length, were gathered from San Diego Bay and fed on three different food concentrations: 0.2, 0.4 and 0.8 mg AFDW L m 1, and their energy balance studied. Food concentration ranges were selected to reflect those observed in the field where the invasive mussel M. senhousia co-occurs with the angiosperm, Zostera marina. The lowest and intermediate concentrations correspond to concentrations described in and over large eelgrass patches, respectively. The upper concentration is equivalent to that occurring during the spring phytoplankton blooms. Ingestion rates varied between 81.6 µg AFDW h m 1 for the mussels fed on the lowest concentration, 191.2 µg AFDW h m 1 when the concentration rose to 0.4 mg AFDW L m 1, and 164.0 µg AFDW h m 1 for the highest concentration. Food concentration had a significant effect on absorption efficiency, which was approximately 70% at the intermediate and upper concentrations, but rose to over 80% at the lowest concentration. The food absorption rate varied with food concentration in a manner similar to that of the ingestion rate, i.e., with a maximum value of 142.34 µg AFDW h m 1 for the mussels fed on the intermediate concentration, this being higher than the values for both the highest concentration (114.72 µg AFDW h m 1) and the lowest (65.89 µg AFDW h m 1). Respiration rates were 54 µg O 2 h m 1 for the mussels fed on the lowest concentration and 74 µg O 2 h m 1 for those fed on the intermediate concentration. These results show a close relationship between respiration and ingestion rates, which can be fitted to the following equation: RR = e (m 0.42 + 0.10 IR) (r = 0.5703, R 2 = 32.53, p <0.01). Scope for growth (SFG) estimations were higher for those mussels fed at the intermediate and upper concentrations (1.95 J h m 1 and 1.50 J h m 1, respectively), between which no significant difference was observed (p > 0.05), whilst SFG for the lowest food concentration was only 0.69 J h m 1. The physiological rate with the greatest effect on growth was the absorption rate. Its relation to SFG is described by the equation SFG = 0.67 + 0.90AR (r = 0.977, R 2 = 95.56%, p <0.01). The discussion of these results is based on the growth rates that have been described for this mussel in its natural environment where habitat structure, such as the canopy provided by the eelgrass, can affect the success of the invasive mussel.     

氯霉素在罗非鱼体内的代谢和消除规律

水产养殖动物口服氯霉素后可能在可食组织中造成残留,本文通过以50mg/kg鱼体重的氯霉素(CAP)的剂量对尼罗罗非鱼单次口灌给药,采用HPLC和GC-ECD分析方法研究了CAP在罗非鱼体内的代谢和消除规律。给药0.5h后,CAP在血浆和肝脏中的浓度均迅速上升,分别为4288.01±1285.53ng/mL和5214.18±1105.62ng/g,2h达到峰值22246.42±355.84ng/mL和25717.47±1740.66ng/g;而肌肉中CAP却上升较慢,2h仅为7744.08±2118.74ng/g,8h才达到峰值13232.89±1612.74ng/g,峰值仅约为血浆和肝脏的1/2。CAP在罗非鱼肌肉和肝脏中的消除速度均较慢,但肌肉比肝脏稍快,肌肉中第96d CAP降至为0.07±0.01ng/g,而肝脏中第120d尚在0.1ng/g以上,为0.25±0.06ng/g。肌肉和肝脏浓度常用对数-时间消除曲线方程分别为y=-0.0966x+5.4292;y=-0.053x+4.7258,二者的T1/2β为7.14d和13.08d。若要使CAP在罗非鱼肌肉和肝脏中的浓度降至0.1ng/g以下,则休药期分别需80.47d和132.61d。试验表明CAP在罗非鱼组织中消除缓慢,尤其在肝脏中,因此肝脏可以作为CAP残留监测的首选组织。       

毛栓菌产漆酶条件优化及该酶对合成染料脱色的特性

【目的】提高菌株Trametes hirsuta SYBC-L19漆酶产量,并研究该酶对合成染料脱色的性质。【方法】通过单因素和响应面设计,对产漆酶培养基进行优化。【结果】最优培养基为:玉米粉20.0 g/L、马铃薯淀粉32.4 g/L、酒石酸铵2.9 g/L、吐温80 0.5 g/L、CuSO4.5H2O 2.0 mmol/L、香兰素0.54 mmol/L、NaH2PO4.2H2O 2.0 g/L、MgSO4.7H2O0.5 g/L、MnSO4.H2O 0.1 g/L;最佳培养条件为:培养温度30°C,初始pH 6.0,装液量40 mL/250 mL,接种量8%。【结论】培养8 d酶活达35 U/mL,是优化前的39倍。对漆酶催化合成染料脱色进行了考察,发现该酶在60°C下对偶氮类染料AR1和RB5能迅速脱色,5 min内即可完成。     

The combined effects of chlorine and ammonia on litter breakdown in outdoor experimental streams

The response of Potamogeton crispus L. breakdown to controlled doses of different levels of chlorine and chlorine + ammonia was investigated over two years in outdoor experimental streams. In 1985, downstream riffles of 2 streams were dosed (observed in-stream concentrations) at ca. 10 μg/L Total Residual Chlorine (TRC), one stream at 64 μg/L TRC and one stream at 230 μg/L TRC. Two control streams were not dosed and the upstream riffles of each stream served as within stream controls. In 1986, the downstream riffle of one stream was dosed at 70 μg/L TRC and a second stream was dosed at 200 μg/L TRC. Four streams were also dosed with 2.5 mg/L NH₃-N: one stream with no chlorine, one stream with ca. 10 μg/L TRC, one with 56 μg/L TRC, and one with 150 μg/L TRC. A seventh stream was dosed for 2 h at 2000 μg/L TRC and 2.5 mg/L ammonia and then allowed to recover (recovery stream). Each year, litter decomposition (degree day k values) was measured during two 35 day trials (Jun–Jul and Aug–Sep). In 1985, when streams were dosed with chlorine alone, decomposition was significantly reduced with the high (230 μg/L TRC) chlorine dose. Downstream decomposition was 27% (Jun–Jul) and 59% (Aug–Sep) of the upstream (control) rate. No other chlorine effects were found during this period. In Jun–Jul 1986, there was significantly lower decomposition in the downstream dosed sites of the 200 μg/L TRC alone stream, the 146 μg/L TRC + ammonia stream and the recovery stream; downstream decay rates were (respectively) 56%, 42% and 64% of the upstream control sites. No other up-down pairs were different in July 1986. In Aug–Sep, all three streams with chlorine + ammonia (6, 56 and 146 μg/L TRC + 2,5 mg/L ammonia) and the 70 μg/L TRC alone stream had significantly lower decomposition rates in the downstream dosed sites. For these streams, downstream decay rates ranged from 46% (high chlorine + ammonia) to 73% (low chlorine + ammonia) of the upstream control rates. No other up-down pairs were different during this trial. Up and downstream sites of the stream dosed with 2.5 mg/L ammonia alone were nearly identical for both trials (< 3% difference). These results indicate that TRC at less than 250 μg/L can significantly reduce litter decomposition and strongly suggest that addition of ammonia to chlorinated water can increase the toxic effect of chlorine. currently at the Department of Fisheries and Wildlife currently at the Department of Fisheries and Wildlife     

Continuous removal of endocrine disruptors by versatile peroxidase using a two‐stage system

The oxidant Mn³⁺‐malonate, generated by the ligninolytic enzyme versatile peroxidase in a two‐stage system, was used for the continuous removal of endocrine disrupting compounds (EDCs) from synthetic and real wastewaters. One plasticizer (bisphenol‐A), one bactericide (triclosan) and three estrogenic compounds (estrone, 17β‐estradiol, and 17α‐ethinylestradiol) were removed from wastewater at degradation rates in the range of 28–58 µg/L·min, with low enzyme inactivation. First, the optimization of three main parameters affecting the generation of Mn³⁺‐malonate (hydraulic retention time as well as Na‐malonate and H₂O₂ feeding rates) was conducted following a response surface methodology (RSM). Under optimal conditions, the degradation of the EDCs was proven at high (1.3–8.8 mg/L) and environmental (1.2–6.1 µg/L) concentrations. Finally, when the two‐stage system was compared with a conventional enzymatic membrane reactor (EMR) using the same enzyme, a 14‐fold increase of the removal efficiency was observed. At the same time, operational problems found during EDCs removal in the EMR system (e.g., clogging of the membrane and enzyme inactivation) were avoided by physically separating the stages of complex formation and pollutant oxidation, allowing the system to be operated for a longer period (～8 h). This study demonstrates the feasibility of the two‐stage enzymatic system for removing EDCs both at high and environmental concentrations. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:908–916, 2015     

Human health risk assessment and source diagnosis of polycyclic aromatic hydrocarbons (PAHs) in the corn and agricultural soils along main roadside in Changchun,China

This work was to investigate distribution characteristics, human health risk assessment, and possible sources of 16 priority polycyclic aromatic hydrocarbons (PAHs) in corn and surface soils of farmlands along main roadside in Changchun City, Jilin Province, China. Total concentrations of 16 PAHs ranged from 1572.4 to 4390.2 µg/kg with a mean value of 2954.9 µg/kg in soils and from 219.9 to 627 µg/kg with a mean value of 362µg/kg in corn. Light-molecular-weight PAHs (2–3 rings) concentration was dominant in soils, accounting for 51%, whereas high-molecular-weight PAHs (5–6 rings) concentration was highest in corn, accounting for 48%. The results of plant concentration factor indicated that high-molecular-weight PAHs have greater mobility. To evaluate potential risk to human health, hazard index (HI) and risk index (RI) were employed. The values of HI for corn and soils were both smaller than 1, indicating that exposure of PAHs posed no or little potential risk to local residents. The fact that values of RI for corn and soils were smaller than 1 × 10^–4 suggested that exposure of PAHs posed no or little cancer risk to local residents. The possible sources of PAHs in corn and soils were both identified as mixture patterns of pyrogenic and petrogenic sources.     

A validated HPLC method for the determination of dimethyl‐4,4′‐dimethoxy‐5,6,5′,6′‐dimethylene dioxybiphenyl‐2,2′‐dicarboxylate (DDB) with fluorescence detection in raw material and pill form: application to an in vitro dissolution test and a content uniformity test

A simple, sensitive and rapid HPLC method with fluorescence detection for the determination of dimethyl‐4,4′‐dimethoxy‐5,6,5′,6′‐dimethylene dioxybiphenyl‐2,2′‐dicarboxylate (DDB) in the raw material and pill form was developed. Liquid chromatography was performed on a C₁₈ column (250 × 4.6 mm i.d., 5 µm particle size), the mobile phase consisted of methanol and 0.05 M sodium dihydrogen phosphate buffer (80 : 20, v/v), and the apparent pH of the mobile phase was adjusted to 3. The fluorescence detector was operated at excitation/emission wavelengths of 275/400 nm. The proposed method allows the determination of DDB within concentration range 0.1–1.5 µg/mL with a limit of detection of 0.032 µg/mL, a limit of quantification of 0.097 µg/mL and a correlation coefficient of 0.9997. The proposed method has been successfully applied for the analysis of DDB in its pills with a percentage recovery of 98.45 ± 0.32. The method was fully validated according to ICH guidelines. Moreover, the high sensitivity of the method permits its use in an in vitro dissolution test for DDB under simulated intestinal conditions. In addition, the proposed method was extended to a content uniformity test according to USP guidelines. Copyright © 2014 John Wiley & Sons, Ltd.