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Perchlorate can disrupt the production of thyroid hormones, impact metabolism, and even affect the cognitive development of infants and toddlers. Typical areas of fireworks manufacturing might face severe perchlorate pollution due to perchlorate is an important raw material. But related study has not been reported. We assess the risk caused by perchlorate and identify the critical exposure pathways for different age/gender groups in typical area of fireworks manufacturing. Liuyang city, a major fireworks manufacturing center in China, was selected as study region. Perchlorate concentrations were measured in 230 local food samples from Liuyang using LC/MS/MS. Risks for different age/gender groups were estimated using a perchlorate intake model. The detection rate of perchlorate in samples from all eight food groups, including vegetables, fruits, meat, seafood, egg, cereal, beans, and drinking water was 100%, and the perchlorate concentrations were higher than those reported in the United States, Canada, South Korea, Kuwait, and other regions of China. Liuyang residents are currently facing an extremely high perchlorate dietary exposure risk, with the mean Estimated Daily Intakes (EDIs) approximately 6–49 times higher than US EPA's recommended reference dose (RfD, 0.7 μg/kg bw/day), and 14–115 times higher than the tolerable daily intake (TDI, 0.3 μg/kg bw/day) established by EFSA. Breast milk and drinking water are identified as the primary exposure pathways for infants and toddlers under the age of two, contributing 44–86% and 13–41% to their total exposure, respectively. For individuals > two years, vegetable consumption (constituting 54–66% of exposures) and ingestion of drinking water (constituting 23–32% of exposures) represent the chief exposure routes. The Hazard Quotient (HQ) values for Liuyang City residents all exceed 2, indicating an extremely high non-carcinogenic risk associated with perchlorate. Scientific and systematic perchlorate pollution control measures should be taken by local government. [Display omitted] • Total 230 samples belonging to 8 kinds of food groups were analyzed for perchlorate, and the detection rate was 100%. • The risk of perchlorate intake at Liuyang City is very high, especially in infants <2 years old. • Key intake factors: breast milk and drinking water (infants <2 years), vegetables and drinking water (people >2 years). [ABSTRACT FROM AUTHOR]

The pollution resulting from the emergence of the contaminant perchlorate is anticipated to have a substantial effect on the water environment in the foreseeable future. Considerable research efforts have been devoted to investigating treatment technologies for addressing perchlorate contamination, garnering widespread international interest in recent decades. A systematic review was conducted utilizing the Web of Science, Scopus, and Science Direct databases to identify pertinent articles published from 2000 to 2024. A total of 551 articles were chosen for in-depth examination utilizing VOS viewer. Bibliometric analysis indicated that countries such as China, the United States, Chile, India, Japan, and Korea have been prominent contributors to the research on this topic. The order of ClO 4 − occurrence was as follows: surface water > groundwater > drinking water. Various remediation methods for perchlorate contamination, such as adsorption, ion-exchange, membrane filtration, chemical reduction, and biological reduction, have been suggested. Furthermore, the research critically evaluated the strengths and weaknesses of each approach and offered recommendations for addressing their limitations. Advanced technologies have shown the potential to achieve notably enhanced removal of perchlorate and co-contaminants from water sources. However, the low concentration of perchlorate in natural water sources and the high energy consumption related to these technologies need to be solved in order to effectively remove perchlorate from water. [Display omitted] • The research hotspots and progress of perchlorate in water were demonstrated. • 551 articles were selected to analyze ClO 4 − occurrence and removal technologies. • Perchlorate research hot spots are China, the United States, and Chile. • Approaches available for ClO 4 − removal over last 20 years was elaborated. • Hybrid treatments were promising green technology of perchlorate removal from water. [ABSTRACT FROM AUTHOR]

Perchlorate, nitrate, and thiocyanate are well-known inhibitors of iodide uptake and thyroid-disrupting chemicals. Widespread human exposure to them has been identified, whereas studies on their internal exposure levels among Chinese pregnant women are scarce and factors associated with them are not well recognized. The objective of this study is to determine their levels and identify the associated factors among pregnant women (n = 1120), based on a prospective birth cohort in Wuhan, central China, using repeated urine samples of three trimesters. Urinary perchlorate, thiocyanate, and nitrate were 100% detected in the samples, and specific gravity-adjusted median concentrations of them in all the samples were 12.6 ng/mL, 367 ng/mL, and 63.7 μg/mL, respectively. Their concentrations were weakly-to-moderately correlated with each other, with Spearman correlation coefficients ranging from 0.27 to 0.54. Poor reproducibility were observed for the three analytes over the three trimesters, with intraclass correlation coefficient of 0.07, 0.19, 0.04 for perchlorate, thiocyanate, and nitrate, respectively. The women who were overweight or used tap water as drinking water had significantly higher perchlorate concentrations, while those with excessive gestational weight gain had significantly higher thiocyanate concentrations (p < 0.05). The women with a college degree or above had lower nitrate concentrations (p < 0.05). Meanwhile, the median concentration of perchlorate in urine samples collected in spring, thiocyanate in those collected in winter, and nitrate in those collected in autumn, was significantly higher compared to their median concentrations in the samples collected in other three seasons (p < 0.05), respectively. Urinary perchlorate and nitrate concentrations of pregnant women in this study were higher than the concentrations of pregnant women in other countries, while thiocyanate concentrations were lower than that of most other countries. This study suggested potential covariates for future epidemiological analyses. [Display omitted] • Perchlorate, thiocyanate, nitrate were 100% detected in urine sample analyzed. • Repeated measurements were performed during three different trimesters of pregnancy. • Their levels were associated to certain demographic factors and sampling seasons. • Women in this study had higher perchlorate and nitrate levels than other countries. [ABSTRACT FROM AUTHOR]

Abstract This study investigates the sulfur (S) disproportionation tendencies in a sulfur packed bed reactor for perchlorate bio-autotrophic reduction at different temperatures. The reactor was operated with over 99% efficiency for 21.00 ± 1.40 mg L−1 perchlorate removal when the hydraulic retention time (HRT) ranged from 12.00 h to 0.75 h at 27 ± 2 °C. When HRT was controlled at 1.00 h, the perchlorate removal efficiency was only 8 ± 1% as the temperature dropped to 6 ± 1 °C. The half-order model fit both perchlorate removal and S disproportionation reaction well. Compared with S disproportionation, the decrease of temperature had a greater influence on perchlorate reduction. As the temperature dropped from 27 ± 2 °C to 6 ± 1 °C, the 1/2 K 1/2 v ,R for perchlorate reduction decreased from 7.37 mg1/2 L−1/2 h−1 to 0.19 mg1/2 L−1/2 h−1. Meanwhile, the 1/2 K 1/2 v ,S for S disproportionation decreased from 3.04 mg1/2 L−1/2 h−1 to 1.96 mg1/2 L−1/2 h−1. The reaction activation energy of perchlorate reduction and S disproportionation was 120.28 kJ mol−1 and 13.44 kJ mol−1, respectively. The S disproportionation reaction proceeded remarkably at the beginning of the reduction, a longer HRT and higher temperature promoted S disproportionation, resulting in excessive sulfate generation and alkalinity consumption. Besides, the spatial distribution of the microbial communities and the dominant bacteria function under different HRTs was analyzed using high-throughput sequencing. Graphical abstract Image 1 Highlights • The acceleration of S disproportionation was discovered. • 21.00 mg/L ClO 4 − was removed >99% at HRT 0.75 h (27 ± 2 °C). • 1/2 kinetics model fit both perchlorate removal and S disproportionation well. • Spatial distribution of the microbial communities was analyzed. • Bacterial α and β diversity, and dominant genus was investigated. [ABSTRACT FROM AUTHOR]

Perchlorate has been categorised as a potential contaminant and researched for years, but there are still many unknowns regarding this anion's contamination impacts. In this review, the basic information about perchlorate is summarised and evaluated, including the physical-chemical properties, fate and transportation, toxicity, analysis, and remediation. Especially, recent advances on analysis and remediation are emphasised and evaluated, such as in-situ imaging analysis and on-site bio-remediation respectively. The high solubility and persistence of the perchlorate anion mean its contamination is different from others, particularly in terms of analysis and remediation that might lead to secondary contamination. The knowledge gaps are listed for future research. [Display omitted] • Perchlorate is reviewed towards analysis and remediation. • Recent advances on the analysis and remediation are emphasised. • Imaging and in-situ analysis is recommended. • Knowledge gaps are listed for future research. [ABSTRACT FROM AUTHOR]

Pure bacteria cell ( Azospira sp. KJ ) and mixed perchlorate reducing bacteria (MPRB) were employed for decomposing the free perchlorate in water as well as the laden perchlorate on surface of quaternary ammonium wheat residuals (QAWR). Results indicated that perchlorate was decomposed by the Azospira sp. KJ prior to nitrate while MPRB was just the reverse. Bio-reduction of laden perchlorate by Azospira sp. KJ was optimal at pH 8.0. In contrast, bio-reduction of laden perchlorate by MPRB was optimal at pH 7.0. Generally, the rate of perchlorate reduction was controlled by the enzyme activity of PRB. In addition, perchlorate recovery (26.0 mg/g) onto bio-regenerated QAWR by MPRB was observed with a small decrease as compared with that (31.1 mg/g) by Azospira sp. KJ at first 48 h. Basically, this study is expected to offer some different ideas on bio-regeneration of perchlorate-saturated adsorbents using biological process, which may provide the economically alternative to conventional methods. [ABSTRACT FROM AUTHOR]

A magnetic amine-crosslinked reed (MACR) was synthesized by an insitu precipitation method and used for perchlorate uptake. The morphological properties of clean MACR, perchlorate-saturated MACR and bio-regenerated MACR samples were determined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and zeta potential measurements. The adsorption capacities of perchlorate by clean and bio-regenerated MACRs were determined. The density functional theory (DFT) method was employed to evaluate the binding free energies between various anions and ammonium/hydroxy groups. The maximum adsorption (Q max ) of perchlorate by MACR was calculated to be 195.5–232.8 mg/g at 30–50 °C. The theoretical computation of adsorption-free energies indicated that ammonium groups were dominant in the process of perchlorate adsorption; other anions, such as [H 2 PO 4 ] - , [NO 3 ] - and [SO 4 ] 2- , showed relatively higher binding free energies than [ClO 4 ] - , which corresponded to the results of competitive adsorption. The spent MACR was then bio-regenerated in a sealed 250-ml conical flask with perchlorate-reducing bacteria (30 °C, 160 rpm) and reached 81.4% of recovery within 3 days. Some hydrophobic macromolecules of extracellular polymeric substances (EPS) might have attached to the surface of MACR, which was validated by the zeta potential, SEM and excitation emission matrix (EEM) fluorescence spectroscopy results. [ABSTRACT FROM AUTHOR]

In the present study we propose a new analytical method for 37 Cl/ 35 Cl analysis in perchlorate by Ion Chromatography(IC) coupled to Multicollector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS). The accuracy of the analytical method was validated by analysis of international perchlorate standard materials USGS-37 and USGS -38; analytical precision better than ±0.4‰ was achieved. 37 Cl/ 35 Cl isotope ratio analysis in perchlorate during laboratory biodegradation experiment with microbial cultures enriched from the contaminated soil in Israel resulted in isotope enrichment factor ε 37 Cl = −13.3 ± 1‰, which falls in the range reported previously for perchlorate biodegradation by pure microbial cultures. The proposed analytical method may significantly simplify the procedure for isotope analysis of perchlorate which is currently applied in environmental studies. [ABSTRACT FROM AUTHOR]

The sensitivity of perchlorate reduction and microbial composition to varied nitrate and acetate loadings was studied in a biologically activated carbon reactor with perchlorate loading and empty bed contact time fixed at 5 mg/L and 226 min, respectively. In stage 1, the sole electron acceptor ClO 4 − realized complete removal with ≥21.95 mg C/L of acetate supply. As nitrate loading gradually increased to 5 mg/L (stage 2), perchlorate reduction was slightly promoted and both ClO 4 − and NO 3 − were completely removed at an acetate loading of 29.7 mg C/L. When nitrate loading continued increasing to 10–60 mg/L (stage 3), perchlorate reduction converted to be inhibited, along with nondetectable NO 3 − and approximately exhausted DOC in effluent. When acetate loading increased to 43.9 mg C/L in stage 4, both ClO 4 − and NO 3 − were again removed, though lags still existed in perchlorate reduction. β-Proteobacteria accounted for about 60%, 55%, 58%, 61% and 12% in samples from the base and top of the filter in stage 1 and those from the base, middle and top in stage 4, respectively. These findings implied that ratio of NO 3 − to ClO 4 − loadings and acetate loading were two key factors impacting ClO 4 − reduction and microbial structure along the filter. [ABSTRACT FROM AUTHOR]

Perchlorate (ClO 4 −) comes under the class of contaminants called the emerging contaminants that will impact environment in the near future. A strong oxidizer by nature, perchlorate has received significant observation due to its occurrence, reactive nature, and persistence in varied environments such as surface water, groundwater, soil, and food. Perchlorate finds its use in number of industrial products ranging from missile fuel, fertilizers, and fireworks. Perchlorate exposure occurs when naturally occurring or manmade perchlorate in water or food is ingested. Perchlorate ingestion affects iodide absorption into the thyroid, thereby causing a decrease in the synthesis of thyroid hormone, a very crucial component needed for metabolism, neural development, and a number of other physiological functions in the body. Perchlorate remediation from ground water and drinking water is carried out through a series of physical–chemical techniques like ion (particle) transfer and reverse osmosis. However, the generation of waste through these processes are difficult to manage, so the need for alternative treatment methods occur. This review talks about the hybrid technologies that are currently researched and gaining momentum in the treatment of emerging contaminants, namely perchlorate. [Display omitted] • Perchlorate (ClO 4 −) is considered as an emerging contaminant. • It has been detected in environmental compartments (groundwater and surface water). • Perchlorate may affect the synthesis of maternal thyroid hormone in pregnancy. • In this study, ecological impact and remediation of perchlorate are reviewed. [ABSTRACT FROM AUTHOR]

Fetuses and infants are vulnerable to perchlorate toxicity. We assessed fetal and infantile exposure to perchlorate in two Chinese cities (Nanchang and Tianjin). Perchlorate was widely found (82%–100%) in breast milk, dissolved infant formula, infants' urine, maternal and cord blood samples. Perchlorate levels in infants' urine (mean ± standard deviation: 22.4 ± 35.6 ng mL −1 ), breast milk (36.6 ± 48.1 ng mL −1 ), and cord blood (3.18 ± 3.83 ng mL −1 ) samples collected from Nanchang and Tianjin were approximately an order of magnitude higher than those reported for the U.S. Perchlorate concentrations in cord blood were comparable to that in maternal blood, indicating that perchlorate is transferred from mother to fetus through placenta. Among all infants providing urine samples, the average daily intake of perchlorate (DOSE U ) was estimated to be 1.17 ± 1.57 μg kg −1 bw d −1 , and 40% of these infants had DOSE U exceeding the RfD (0.7 μg kg −1 bw d −1 ) recommended by U.S. EPA. However, approximately 70% of exclusively breast-fed infants had perchlorate exposure dose via breast milk exceeding the RfD. For breast-fed infants, breast milk was the overwhelmingly predominant exposure pathway; while infant formula and indoor dust ingestion were major perchlorate exposure sources for formula-fed infants. To our knowledge, this is the first report to assess the fetal and infantile exposure to perchlorate in China. [ABSTRACT FROM AUTHOR]

A heterotrophic sulfur autotrophic integrated fluidized bed reactor was established for simultaneous and efficient removal of ClO 4 − and NO 3 − from water. The optimum operating conditions forecasted through the response surface method (RSM) were the hydraulic retention time (HRT) of 0.50 h, the influent acetate (CH 3 COO−) concentration of 55 mg/L and the reflux ratio of 14, contributing to ClO 4 − and NO 3 − removal of 98.99% and 99.96%, respectively, without secondary pollution caused by residual carbon (NPOC <3.89 mg/L). Meanwhile, the effluent pH fluctuated in a range of 6.70–8.02 and sulfur-containing by-products (i.e., SO 4 2− and S2−) could be controlled by adjusting operation conditions throughout the experimental stage. The increase of the influent CH 3 COO− concentration reduced the load borne by autotrophic reduction process and further reduced SO 4 2− production. Shortening HRT, increasing the influent CH 3 COO− concentration and decreasing the reflux ratio could all reduce alkalinity consumption. Shortening HRT and decreasing the reflux ratio could shorten contact time between sulfur and water and thus inhibit S0 disproportionation. High-throughput sequencing result showed that Proteobacteria and Chlorobi were the dominant bacteria. Sulfurovum , Sulfuricurvum and Ignavibacterium were the major heterotrophic denitrifying bacteria (DB)/perchlorate reducing bacteria (PRB), Ferritrophicum and Geothrix were DB, and Chlorobaculum was S0 disproportionation bacteria. [Display omitted] • A mixotrophic fluidized bed reactor is set up with S0 and acetate as electron donors. • Simultaneous and efficient removal of ClO 4 − (98.99%) and NO 3 − (99.96%) is realized. • Shortening HRT and decreasing the reflux ratio can inhibit S0 disproportionation. • In the entire experiments, the effluent NPOC is kept at a low level (<3.89 mg/L). • The effluent pH is at 6.70–8.02, and is suitable for the growth of DB/PRB. [ABSTRACT FROM AUTHOR]

This study investigated the potential of a novel fabricated black phosphorus (BP) nanoparticle electrode as an alternative to noble metal-based catalysts for application in electrolysis. The BP electrode was compared with other conventional catalysts (boron-doped diamond (BDD) and a dimensional stable electrode (DSA)) under different electrolyte conditions for the generation of specific oxidants (e.g., OH•, HOCl, OCl−, SO 4 • -) in the bulk phase during electrolysis. In the presence of sulfate-based electrolyte, results on the electrochemical oxidation showed that the BP not only resulted in an 8-fold increase in the current efficiency compared to DSA, but also reduced energy consumptions by approximately 30-fold. Moreover, electrolysis using certain electrodes (i.e., BDD) under high current densities in the presence of chlorine-based electrolyte has been reported to be hazardous to the water system due to the generation of toxic chlorine oxyanions (i.e., perchlorate), which necessitates the operation of a post-treatment process. Likewise, application of the BDD electrode was confirmed to produce perchlorate under high current densities, while no by-product was generated by electrolysis with the BP electrode. Finally, multiple degradation pathways for selective water treatment was monitored under oxidation with the BP electrode. To the best of our knowledge, this study is the first to apply the novel fabricated BP electrode as the anodic catalyst for the treatment of a water system. [Display omitted] • Fabrication of novel black phosphorus (BP) anodic catalyst for electrolysis. • Superior electrochemical activity and stability for effective operation. • Safe application with no generation of toxic disinfection by-products. • High organic decomposition performance under various electrolyte conditions. [ABSTRACT FROM AUTHOR]

Indoor and outdoor concentrations of PM 2.5 -associated perchlorate (ClO 4 − ) and chlorate (ClO 3 − ) were investigated in Jinan, China, and size-resolved perchlorate and chlorate were studied in Kumamoto, Japan. The average outdoor PM 2.5 -associated concentrations of perchlorate and chlorate were 4.18 ng m −3 and 2.82 ng m −3 , respectively, in Jinan. Perchlorate and chlorate were mainly distributed in fine particles, and their approximate PM 2.5 -associated concentrations were 0.04 ng m −3 and 4.14 ng m −3 , respectively, in Kumamoto. The ratios of ClO 3 − /ClO 4 − ranged from 18.72 to 360.22 in Kumamoto and from 0.03 to 7.45 in Jinan. The highest concentration of perchlorate (173.76 ng m −3 ) was observed on Spring Festival Eve. This finding and the significant correlation between perchlorate and fireworks-related components (Cl − and K + ) indicated that the fireworks display was a significant source of perchlorate in Jinan. The indoor concentrations of perchlorate and chlorate in Jinan were 3.54 ng m −3 (range, 0.14–125.14 ng m −3 ) and 0.94 ng m −3 (range, 0.10–1.80 ng m −3 ), respectively. In the absence of an indoor source of perchlorate, the occurrence of indoor concentrations higher than those found outdoors was a common effect of individual fireworks displays near the sampling sites, coupled with meteorological influences and poor indoor diffusion conditions. The exposure risks of perchlorate and chlorate indoors indicated that the potential risk of perchlorate exposure to children during fireworks displays is deserving of concern. [ABSTRACT FROM AUTHOR]

Although China is the largest producer of fireworks (perchlorate-containing products) in the world, the pathways through which perchlorate enters the environment have not been characterized completely in this country. In this study, perchlorate, iodide and thiocyanate were measured in 101 water samples, including waste water, surface water, sea water and paired samples of rain water and surface runoff collected in Tianjin, China. The concentrations of the target anions were generally on the order of rain > surface water ≈ waste water treatment plant (WWTP) influent > WWTP effluent. High concentrations of perchlorate, iodide and thiocyanate were detected in rain samples, ranging from 0.35 to 27.3 (median: 4.05), 0.51 to 8.33 (2.92), and 1.31 to 107 (5.62) ng mL-1, respectively. Furthermore, the concentrations of the target anions in rain samples were significantly (r = 0.596-0.750, p < 0.01) positively correlated with the concentrations obtained in the paired surface runoff samples. The anions tested showed a clear spatial distribution, and higher concentrations were observed in the upper reaches of rivers, sea waters near the coast, and rain-surface runoff pairs sampled in urban areas. Our results revealed that precipitation may act as an important source of perchlorate, iodide and thiocyanate in surface water. Moreover, iodide concentrations in the Haihe River and Dagu Drainage Canal showed a good correlation with an ideal marker (acesulfame) of domestic waste water, indicating that input from domestic waste water was an important source of iodide in the surface waters of Tianjin. [ABSTRACT FROM AUTHOR]

Various studies have evaluated the accumulation of ClO4- in lettuce (Lactuca sativa), but very few have dealt with the variables that can interfere with its capture. The present study evaluates the transfer of ClO4- in two L. sativa varieties: butter head (L. sativa var. capitata) and cos lettuce (L. sativa var. crispa) under hydroponic conditions. The ClO4- concentrations used correspond to levels (1 and 2 mg L-1), measured in irrigation water in the Iquique region in the north of Chile. Results indicate that the capture of ClO4- is dependent on its concentration, lettuce genotype, and temperature. The butter head variety accumulates the highest perchlorate concentrations. Anion competition involving NO3- (16 and 48 mM), Cl- (23 and 56 mM), and SO42- (10 and 20 mM) was evaluated, being NO3- (48 mM), the most significant competition reducing the concentration of ClO4- in tissues of L. sativa varieties. [ABSTRACT FROM AUTHOR]

The potential neurotoxic and carcinogenic effects of the explosives compound RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) on human health requires groundwater remediation strategies to meet low cleanup goals. Bioremediation of RDX is feasible through biostimulation of native microbes with an organic carbon donor but may be less efficient, or not occur at all, in the presence of the common co-contaminants perchlorate and nitrate. Laboratory tests compared biostimulation with bioaugmentation to achieve anaerobic degradation of RDX, perchlorate, and nitrate; a field pilot test was then conducted in a fractured rock aquifer with the selected bioaugmentation approach. Insignificant reduction of RDX, perchlorate, or nitrate was observed by the native microbes in microcosms, with or without biostimulation by addition of lactate. Tests of the RDX-degrading ability of the microbial consortium WBC-2, originally developed for dehalogenation of chlorinated volatile organic compounds, showed first-order biodegradation rate constants ranging from 0.57 to 0.90 per day (half-lives 1.2 to 0.80 days). WBC-2 sustained degradation without daughter product accumulation when repeatedly amended with RDX and lactate for a year. In microcosms with groundwater containing perchlorate and nitrate, RDX degradation began without delay when bioaugmented with 10% WBC-2. Slower RDX degradation occurred with 3% or 5% WBC-2 amendment, indicating a direct relation with cell density. Transient RDX daughter compounds included methylene dinitramine, MNX, and DNX. With WBC-2 amendment, nitrate concentrations immediately decreased to near or below detection, and perchlorate degradation occurred with half-lives of 25–34 days. Single-well injection tests with WBC-2 and lactate showed that the onset of RDX degradation coincided with the onset of sulfide production, which was affected by the initial perchlorate concentration. Biodegradation rates in the pilot injection tests agreed well with those measured in the microcosms. These results support bioaugmentation with an anaerobic culture as a remedial strategy for sites contaminated with RDX, nitrate, and perchlorate. [Display omitted] • High nitrate and perchlorate may impede anaerobic RDX biodegradation in aquifers. • Organic donor did not stimulate biodegradation of RDX, perchlorate, and nitrate. • Adding an anaerobic mixed culture with the donor resulted in rapid biodegradation. • WBC-2 culture sustained RDX degradation for a year without metabolite accumulation. • Field tests verify bioaugmentation as feasible remedy for RDX and co-contaminants. [ABSTRACT FROM AUTHOR]

Abstract: Impact of pregnancy on levels of urinary perchlorate, thiocyanate, and nitrate has not been studied using large scale data. Data from National Health and Nutrition Examination Survey for the years 2003–2008 were used to evaluate risk factors that impact levels of these contaminants among females of child bearing age. In addition to pregnancy, other risk factors evaluated were: age, race/ethnicity, smoking status, serum triglyceride levels, and iodine deficiency status. Pregnancy did not affect the levels of perchlorate and nitrate but, new to this study, it was found that thiocyanate levels were statistically significantly lower among pregnant females as compared to non-pregnant females (p <0.01). Iodine deficient females had statistically significantly lower levels of these contaminates than iodine replete females (p <0.01). Levels of thiocyanate among smokers were about five times higher than among non-smokers. Non-Hispanic Blacks had the lowest and Mexican Americans had the highest levels of perchlorate and nitrate. The reverse was true for thiocyanate levels. There was an inverse association between nitrate and education levels. There was a positive association between serum triglyceride levels and the levels of these contaminants. Also, new to this study, of concern, was the fact that levels of these contaminants increased among females over the period 2005–2008. Levels of perchlorate, thiocyanate, and nitrate did not vary across pregnancy trimesters. [Copyright &y& Elsevier]

Abstract: Seasonal variation and influencing factors of perchlorate in snow, surface soil, rain, surface water, groundwater and corn were studied. Seven hundreds and seventy samples were collected in different periods in Harbin and its vicinity, China. Perchlorate concentrations were analyzed by ion chromatography–electrospray mass spectrometry. Results indicate that fireworks and firecrackers display from the Spring Festival to the Lantern Festival (February 2, 2011–February 17, 2011) can result in the occurrence of perchlorate in surface soil and snow. Perchlorate distribution is affected by wind direction in winter. Melting snow which contained perchlorate can dissolve perchlorate in surface soil, and then perchlorate can percolate into groundwater so that perchlorate concentrations in groundwater increased in spring. Perchlorate concentrations in groundwater and surface water decrease after rainy season in summer. Groundwater samples collected in the floodplain areas of the Songhua River and the Ashi River contained higher perchlorate concentrations than that far away with the rivers. The corns have the ability to accumulate perchlorate. [Copyright &y& Elsevier]

Abstract: Decomposition of perchlorate () in pressurized hot water (PHW) was investigated. Although demonstrated little reactivity in pure PHW up to 300°C, addition of zerovalent metals to the reaction system enhanced the decomposition of to Cl− with an increasing order of activity of (no metal)≈Al

Abstract: Exposure to perchlorate is widespread in the United States and many studies have attempted to character the perchlorate exposure by estimating the average daily intakes of perchlorate. These approaches provided population-based estimates, but did not provide individual-level exposure estimates. Until recently, exposure activity database such as CSFII, TDS and NHANES become available and provide opportunities to evaluate the individual-level exposure to chemical using exposure surveillance dataset. In this study, we use perchlorate as an example to investigate the usefulness of urinary biomarker data for predicting exposures at the individual level. Specifically, two analyses were conducted: (1) using data from a controlled human study to examine the ability of a physiologically based pharmacokinetic (PBPK) model to predict perchlorate concentrations in single-spot and cumulative urine samples; and (2) using biomarker data from a population-based study and a PBPK model to demonstrate the challenges in linking urinary biomarker concentrations to intake doses for individuals. Results showed that the modeling approach was able to characterize the distribution of biomarker concentrations at the population level, but predicting the exposure–biomarker relationship for individuals was much more difficult. The type of information needed to reduce the uncertainty in estimating intake doses, for individuals, based on biomarker measurements is discussed. [Copyright &y& Elsevier]

Abstract: Perchlorate is a known endocrine disruptor present in groundwater, vegetables and dairy food products in many regions of the United States. It interferes with the uptake of iodide into the thyrocyte by the sodium–iodide symporter at the basolateral surface, thus potentially disrupting the synthesis of thyroid hormone. Because transport of iodide from the thyroid follicular cells to the follicular lumen is mediated by the protein pendrin at the apical surface, we hypothesized that perchlorate may also interact with this protein. Therefore, HeLa cells were transfected with the human SLC26A4 gene, which encodes pendrin, to generate an in vitro mammalian system expressing the recombinant pendrin protein (HeLa-PDS). The HeLa-PDS cells, along with untransfected cells, were then cultured in presence of iodide and/or perchlorate. Intracellular levels of these two chemicals were measured by ion chromatography tandem mass spectrometry. Results from this study show that iodide and perchlorate uptake increases significantly in HeLa-PDS cells as compared to untransfected cells. Thus, recombinant HeLa cells expressing pendrin protein accumulate iodide and perchlorate intracellularly, indicating that pendrin is involved in the uptake of perchlorate. Additional results from this study suggest that iodide and perchlorate competitively inhibit each other for uptake by pendrin. The ability of perchlorate to compete with iodide for uptake by both basal and apical transporters may increase the potential of perturbation of thyroid homeostasis and therefore the estimated risk posed to susceptible human populations. [Copyright &y& Elsevier]

Abstract: As a new threat to environment all through the world, perchlorate () was predominantly a thyrotoxin, and its toxic manifestations in non-thyroid were also documented. However, little is known about the effects of on cell and organelle. Therefore, the present study was designed to investigate the effects of on hepatocytes and mitochondria isolated from Carassius auratus from the direct viewpoint of energy by using the microcalorimetric method. The metabolic thermogenic curves of hepatocytes and mitochondria at 25°C were obtained. And the thermokinetic parameters, such as growth rate constant (k), inhibitory ratio (I), maximum thermal power (P max) and total thermal effect (Q total) have been calculated. The results indicated that the toxicity of on hepatocytes was relevant to the concentration of . However, 10–100mgL−1 stimulated the metabolic activity of mitochondria and the toxicity of on mitochondria only occurrenced when treated with higher concentration of . This study shown that mitochondria has a major impact on the metabolic thermogenic of hepatocytes, but not the only factor. Meanwhile, it demonstrated that microcalorimetry was a powerful tool for understanding biological processes and studying on the toxic action of environmental contaminants in cell or subcellular level. [Copyright &y& Elsevier]

Abstract: Perchlorate has been detected in dairy milk and milk-based powdered infant formula samples from many different provinces of South Korea. A total of 37 dairy milk samples from 12 different brands and 26 milk-based powdered infant formula samples from four different brands were tested for the presence of perchlorate. These brands and their products, which are analyzed in this study, cover over 95% of the dairy milk and milk-based powdered infant formula market share in South Korea, which has a population of approximately 50 million inhabitants. Perchlorate was explicitly detected by ion chromatography tandem mass spectrometry; the limit of quantification (LOQ) for dairy milk and milk-based powdered infant formula was 0.12μgL−1 and 1.0μgkg−1, respectively. The perchlorate concentration in all the samples was above the LOQ. The perchlorate detection data is given as follows: 1.99–6.41μgL−1 (n =37, mean concentration=4.59±0.17μgL−1) for dairy milk and 1.49–33.3μgkg−1 (n =26, mean concentration=7.83±0.22μgkg−1) for milk-based infant formula. This study provides increasing evidence that perchlorate commonly occurs in dairy products, presumably as the result of perchlorate intake by dairy cattle from water and feed. [ABSTRACT FROM AUTHOR]

Abstract: Removal of perchlorate using either acid-washed zero-valent aluminum or aluminum hydroxide was studied in batch reactors under ambient temperature and pressure. Approximately 90–95% of perchlorate was removed within 24h in the presence of 35gL−1 aluminum at acidic pH (4.5±0.2). Although aluminum is a strong reductant, this study indicated no explicit evidence to support perchlorate reduction while it was found that an adsorption process is involved in the perchlorate removal. The adsorbed perchlorate ions were desorbed effectively using a 1.0N MgSO4 solution. The effective composition for the perchlorate adsorption is confirmed as aluminum hydroxide (bayerite), which is a product of the aluminum corrosion. Rapid adsorption of perchlorate was observed in the presence of aluminum hydroxide. The perchlorate adsorption by aluminum hydroxide is dependent on the solution pH. The removal mechanism can be attributed to the ion-pair formation at the aluminum hydroxide surface. [Copyright &y& Elsevier]

Abstract: Spea multiplicata (New Mexico spadefoot toad) larvae were exposed to 60, 110, and 1000μgL−1 perchlorate dissolved in natural surface water to determine risks associated with perchlorate exposure in desert-adapted anurans. Hind- and forelimb development and tail resorption were measured to identify effects of perchlorate exposure. No perchlorate-related effects on snout-vent length, hindlimb length, and proportion metamorphosed were observed in the highest treatment group (positive control; 1000μgL−1) suggesting that either S. multiplicata are not sensitive to the effects of perchlorate at the concentrations tested or that unidentified constituents of natural surface water mitigated perchlorate toxicity. To identify whether surface water mitigated perchlorate toxicity, Xenopus laevis were exposed to 20 and 60μgL−1 perchlorate in surface water and synthetic laboratory prepared water (i.e., FETAX media). X. laevis exposed to perchlorate dissolved in surface water exhibited no perchlorate-related anti-metamorphic effects, whereas X. laevis exposed to perchlorate in FETAX media experienced changes in percent metamorphosing (p <0.001), time to metamorphosis (p <0.001), snout-vent length (p <0.001), and hindlimb length (p <0.001) as compared to FETAX controls. These results suggest that natural surface water can mediate perchlorate effects at concentrations up to 60μgL−1 for X. laevis and greater than 1mgL−1 for S. multiplicata, potentially due to physicochemical properties of surface water. Capsule: This manuscript discusses the effects of perchlorate in natural surface water to S. multiplicata and X. laevis. [Copyright &y& Elsevier]

Abstract: Rejection characteristics of chromate, arsenate, and perchlorate were examined for one reverse osmosis (RO, LFC-1), two nanofiltration (NF, ESNA, and MX07), and one ultrafiltration (UF and GM) membranes that are commercially available. A bench-scale cross-flow flat-sheet filtration system was employed to determine the toxic ion rejection and the membrane flux. Both model and natural waters were used to prepare chromate, arsenate, and perchlorate solutions (approximately 100μgL−1 for each anion) in mixtures in the presence of other salts (KCl, K2SO4, and CaCl2); and at varying pH conditions (4, 6, 8, and 10) and solution conductivities (30, 60, and 115mSm−1). The rejection of target ions by the membranes increases with increasing solution pH due to the increasingly negative membrane charge with synthetic model waters. Cr(VI), As(V), and rejection follows the order LFC-1 (>90%) > MX07 (25–95%)≅ESNA (30–90%)>GM (3–47%) at all pH conditions. In contrast, the rejection of target ions by the membranes decreases with increasing solution conductivity due to the decreasingly negative membrane charge. Cr(VI), As(V), and rejection follows the order CaCl2 90%) excluding (71–74%) than the ESNA NF membrane (11–56%) with a relatively large pore size (0.44nm), indicating that size exclusion is at least partially responsible for the rejection. The ratio of solute radius (ri,s ) to effective membrane pore radius (rp ) was employed to compare ion rejection. For all of the ions, the rejection is higher than 70% when the ri,s/rp ratio is greater than 0.4 for the LFC-1 membrane, while for di-valent ions (, , and ) the rejection (38–56%) is fairly proportional to the ri,s /rp ratio (0.32–0.62) for the ESNA membrane. [Copyright &y& Elsevier]

Abstract: The perchlorate anion () is present in food, drinking water, groundwater, and surface waters. Exposure to perchlorate is of concern, due to the ability of the anion to disrupt the function of the thyroid gland, and affect the synthesis of thyroid hormones. In this study, liquid chromatography – tandem mass spectrometry (LC–MS/MS) method has been optimized to analyze for perchlorate in blood sera and plasma samples from 84 US donors. In addition, 15 volunteers provided saliva and serum samples concurrently, to enable assessment of the ratio of perchlorate in these two matrices. Recoveries of perchlorate from fortified blanks and from serum/plasma samples were between 92% and 97%. Replicate analysis of blood-matrix spikes had a relative standard deviation (RSD) of <3%, and the relative percent difference (RPD) of repeat analysis of samples was <4%. Perchlorate concentrations in serum and plasma ranged from below the limit of quantitation (0.05ngmL−1) to a maximum of 7.7ngmL−1. Perchlorate concentrations in serum and plasma were log-normally distributed. The mean and median concentrations of perchlorate in 84 serum and plasma samples were 0.32 and 0.17ngmL−1, respectively. No significant difference existed in perchlorate concentrations between serum and plasma. Analysis of paired saliva and serum samples showed a significant positive correlation for log-normalized perchlorate concentrations (r 2 =0.60) and perchlorate concentrations themselves (r 2 =0.86). The mean saliva:serum concentration ratio of perchlorate was 14:1 (after exclusion of two pairs of outliers). This is the first report to provide measurement data for perchlorate in blood sera and plasma of populations in the US. [Copyright &y& Elsevier]

Perchlorate (), which is used as an oxidizer in jet and rocket fuels, pyrotechnic devices and explosives, is a widespread contaminant in surface waters and groundwater of many countries. Perchlorate is known to affect thyroid function. Despite the compound’s widespread occurrence and potential health effects, perchlorate levels in drinking water in India are not known. In this study, water samples collected from 13 locations in six states (n =66), and saliva samples collected from four locations in three states (n =74) in India, were analyzed for perchlorate using high performance liquid chromatography interfaced with tandem mass spectrometry (HPLC–MS/MS). Perchlorate was detected in most (76%) of the water samples analyzed at concentrations above the quantitation limit of 0.02μgL−1; concentrations ranged from <0.02 to 6.9μgL−1 (mean: 0.42±1.1μgL−1; median: 0.07μgL−1). Mean concentrations of perchlorate in drinking water, groundwater, bottled water, surface water and rain water were 0.1, 1.0, <0.02, 0.05 and <0.02μgL−1, respectively. From a total of 66 water samples analyzed, only three samples contained perchlorate levels above 1μgL−1; all three were groundwater samples. Perchlorate was found in the saliva samples analyzed at concentrations above 0.2μgL−1 and up to 4.7μgL−1 (mean: 1.3±1.3μgL−1; median: 0.91μgL−1). No remarkable differences in perchlorate concentrations were found among the sampling locations of water or saliva or in subgroups stratified by gender or age. Perchlorate concentrations in water samples from India are one to two orders of magnitude lower than the concentrations reported for the United States. [Copyright &y& Elsevier]

Rainwater contains multiple oxidants, such as hydrogen peroxide (H 2 O 2) and perchlorate (ClO 4 −). The aim of the study was to investigate the rainwater of trace H 2 O 2 and ClO 4 − affected on the arsenic (As) methylation and volatilization in the rice paddy of As contamination (arsenite (As(III)) and roxarsone (Rox)). Heavy rainfall monitoring and simulation experiments were applied in this study. The result showed that the H 2 O 2 and ClO 4 − of heavy rainfall in 2017 was 5.3–51.6 μmol/L and ND - 6.1 μg/L respectively. Because of the differences in chemical properties, H 2 O 2 and ClO 4 − affected As methylation and volatilization of paddy soil in different ways. H 2 O 2 performed a temporary effect on As volatilization, which was mainly in the 1st-hour and restored to the controls condition finally. However, ClO 4 − showed a persistent inhibition on As volatilization which decreased 32 %–69 % in the whole test. In general, the trend of volatilization was following the order: CK ≈ H 2 O 2 > ClO 4 −. The oxidants (H 2 O 2 and ClO 4 −) also could decrease As(III) in 37 %–44 % and increased As(V) in 24 %–272 %. In addition, planting rice in As contamination soil could enhance As volatilization by 36 %–334 %. These suggested that planting wetland plants on As-contaminated soil probably become a potential way to increase As volatilization. [Display omitted] • H 2 O 2 could temporarily effect on As volatilization in soil. • ClO 4 − could persistently inhibit on As volatilization in soil. • Planting rice could enhance As volatilization in soil. [ABSTRACT FROM AUTHOR]

Perchlorate is a disinfection by-product (DBP) of serious health concern. Herein, the long sought mechanism of high perchlorate production during electrochemical disinfection at boron-doped diamond (BDD) anode in the presence of chloride was elucidated. The generated perchlorate at BDD during electrochemical disinfection (in 10 mM NaCl) in 60 min reached 0.125 mM, which was 830 times higher than the EPA standard. In contrast, perchlorate at PbO 2 and SnO 2 anodes was below the detection limit. Further experiments employing NaClO 3 revealed that the conversion ratio from ClO 3 − to ClO 4 − in 10 h at BDD (98%) was considerably higher than PbO 2 (13%) and SnO 2 (12%). Such significant difference among anodes was fully interpreted with a two-step mechanism. The first step is essential to produce ·ClO 3 by oxidizing ClO 3 − at electrodes. Otherwise, the conversion to perchlorate would be impossible even with excessive ·OH, which was verified with the photocatalysis process. The second step is the perchlorate generation with radical reaction between ·ClO 3 and ·OH, where the primary role of ·OH was substantiated by scavenging test. Interestingly, the capability of perchlorate production was correlated with free ·OH instead of the total amount of ·OH. Despite the similar abilities of electron transfer between anodes and ClO 3 −, much higher free ·OH exists at BDD anode than at PbO 2 and SnO 2 anodes through chronoamperometry experiments and work function characterization, which reasonably provides interpretation of high perchlorate production at BDD anode. • Formation mechanism of high perchlorate at BDD was thoroughly interpreted. • Electrodes played a key role in generation of ·ClO 3 from oxidation of ClO 3 −. • Primary importance of ·OH with ·ClO 3 for perchlorate generation was confirmed. • Capability of perchlorate production was more relevant to free hydroxyl radicals. [ABSTRACT FROM AUTHOR]

Perchlorate is an oxidizer that has been routinely used in solid rocket motors by the Department of Defense and National Aeronautics and Space Administration. Royal Demolition Explosive (RDX) is a major component of military high explosives and is used in a wide variety of munitions. Perchlorate bearing wastewater typically results from production of solid rocket motors, while RDX is transferred to Army industrial wastewaters during load, assemble and pack operations for new munitions, and hot water or steam washout for disposal and deactivation of old munitions (commonly referred to as demilitarization, or simply demil). Biological degradation in Anaerobic Fluidized Bed Reactors (AFBR), has been shown to be an effective method for the removal of both perchlorate and RDX in contaminated wastewater. The focus of this study was to determine the effectiveness of removal of perchlorate and RDX, individually and when co-mingled, using ethanol as an electron donor under steady state conditions. Three AFBRs were used to assess the effectiveness of this process in treating the wastewater. The performance of the bioreactors was monitored relative to perchlorate, RDX, and chemical oxygen demand removal effectiveness. The experimental results demonstrated that the biodegradation of perchlorate and RDX was more effective in bioreactors receiving the single contaminant than in the bioreactor where both contaminants were fed. [Copyright &y& Elsevier]

Abstract: Exposure to perchlorate or other thyrotoxic compounds can cause hypothyroidism in most vertebrates, and this may affect levels of endogenous antioxidants and cause oxidative stress. Arsenic also induces oxidative stress in animals by modifying the antioxidant capacity and may alter the thyroid homeostasis. Therefore, hypothyroidism may affect the toxicity of arsenate. In order to test this hypothesis, zebrafish (Danio rerio) were made hypothyroid by exposure to perchlorate, and toxicity of arsenate in hypothyroid and euthyroid fish was compared. The endpoints were LC50 and thyroid histopathology. Additionally, the recovery of thyroid histopathological indices after cessation of perchlorate exposure was determined. The current study showed that 96h LC50 of perchlorate anion and arsenate ion to juveniles fish (37day post-fertilization) were 2532 and 56mgl−1, respectively. In addition, hypothyroid fish were more sensitive to arsenate, with a 96h LC50 of 43mgl−1. Growth rates were also significantly retarded by perchlorate exposure. After cessation of perchlorate exposure, there was recovery of thyroid histopathology in terms of epithelial cell height, but not colloid area or growth rate. In conclusion, perchlorate enhances arsenate toxicity to juvenile zebrafish, and the rate of thyroid recovery after cessation of perchlorate exposure depends on the endpoints examined. [Copyright &y& Elsevier]

has recently been recognized as a widespread contaminant of surface and ground water. This research investigated chemolithotrophic perchlorate reduction by bacteria in soils and sludges utilizing inorganic electron-donating substrates such as hydrogen, elemental iron, and elemental sulfur. The bioassays were performed in anaerobic serum bottles with various inocula from anaerobic or aerobic environments. All the tested sludge inocula were capable of reducing perchlorate with H2 as electron donor. Aerobic activated sludge was evaluated further and it supported perchlorate reduction with Fe0 and S0 additions under anaerobic conditions. Heat-killed sludge did not convert , confirming the reactions were biologically catalyzed. (3mM) was almost completely removed by the first sampling time on d 8 with H2 (⩾0.37mMd−1), after 22d with S0 (0.18mM d−1) and 84% removed after 37d with Fe0 additions (0.085mMd−1). Perchlorate-reduction occurred at a much faster rate (1.12mMd−1), when using an enrichment culture developed from the activated sludge with S0 as an electron donor. The enrichment culture also utilized S2− and as electron-donating substrates to support reduction. The mixed cultures also catalyzed the disproportionation of S0 to S2− and . Evidence is presented demonstrating that S0 was directly utilized by microorganisms to support perchlorate-reduction. In all the experiments, was stoichiometrically converted to chloride. The study demonstrates that microorganisms present in wastewater sludges can readily use a variety of inorganic compounds to support perchlorate reduction. [Copyright &y& Elsevier]

We report the ability of nickel-based catalysts to degrade explosives compounds in aqueous solution. Several nickel catalysts completely degraded the explosives, although rates varied. Nearly all of the organic explosive compounds tested, including 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), were rapidly degraded to below detection limits by a powdered nickel on an alumina-silicate support (Aldrich nickel catalyst). Perchlorate degradation was minimal (<25%). Degradation of TNT by Aldrich nickel catalyst resulted in apparent first-order kinetics. Significant gaseous 14C was released and collected in an alkaline solution (most likely carbon dioxide) from [14C]RDX and [14C]HMX, indicating heterocyclic ring cleavage. Significant gaseous 14C was not produced from [14C]TNT, but spectrophotometric evidence indicated loss of aromaticity. Degradation occurred in low ionic strength solutions, groundwater, and from pH 3 to pH 9. Degradation of TNT, RDX, and HMX was maintained in flow-through columns of Aldrich nickel catalyst mixed with sand down to a hydraulic retention time of 4h. These data indicate that nickel-based catalysts may be an effective means for remediation of energetics-contaminated groundwater. [Copyright &y& Elsevier]

Perchlorate is a stable anion that has been introduced into the environment through activities related to its production and use as a solid rocket propellant. Perchlorate is thought to transport through soils without being adsorbed; thus, for determination of perchlorate in soil, samples are typically extracted with water prior to analysis. The completeness of extraction depends on perchlorate existing as a free ion within the soil matrix. In this study, perchlorate extraction efficiency was evaluated with five soil types under two different oxygen states. For each soil, 30% (w/w) slurries were prepared and equilibrated under either oxic or anoxic conditions prior to spiking with a stock solution of sodium perchlorate, and the slurries were then maintained for 1-week or 1-month. At the end of the exposure, slurries were centrifuged and separated into aqueous and soil phases. After phase separation, the soil was washed first with deionized water and then with 50mM NaOH, producing second and third aqueous phases, respectively. Perchlorate concentrations in the three aqueous phases were determined using ion chromatography. The results obtained from this study suggest that matrix interference and signal suppression due to high conductivity have greater effects upon observed perchlorate concentrations by ion chromatography than does perchlorate interaction with soil. Thus, a single water extraction is sufficient for quantitative determination of perchlorate in soil. [Copyright &y& Elsevier]

Abstract: Trace level perchlorate analysis in water initiated a new development in the Ion Chromatography (IC) technology. Maintenance of a low detection limit may be highly affected by the operating conditions of the IC system. In this paper the homoscedasticity of the IC system within the calibration concentration range, the effect of the system drift on the calibration curve and the effect of the self regeneration suppressor (SRS) current on the detection limit were investigated. The experimental results were evaluated by statistical methods such as the Cochran test and the lack of fit test. The detection limits were obtained by two ways. One through method detection limit (MDL) and the other through detection limit from the calibration curve (DTC). The Cochran test results revealed the homoscedasticity of the IC system. The effect of system drift on the calibration curve was noticed by the lack of fit test. MDL yielded a lower but less reliable detection limit than DTC. An acceptable detection limit can be achieved under the lower SRS current (100mA). [Copyright &y& Elsevier]

Abstract: Surface water samples were collected from 55 sites in the Great Lakes Basin and analyzed for the presence of perchlorate using HPLC/MS/MS with an isotopically enriched internal standard. Sites included areas impacted by heavy industry, urbanization, agriculture and atmospheric deposition. Perchlorate was detected at several of the sites at concentrations close to the method detection limit (0.2μg/l). Despite these low concentrations, its presence was confirmed by sample concentration and determination of the isotopic ratio of perchlorate. The presence of perchlorate at two of the sites was related to a fireworks display which had occurred prior to sampling. The other detections of perchlorate were in rivers/creeks draining watersheds which had high density livestock and crop farming activity. We suspect the two are related. To our knowledge, these are the first reported concentrations of perchlorate in Canadian surface waters. [Copyright &y& Elsevier]

The purpose of this work was to explore the reductive bioremediation potential of a perchlorate-enriched facultative anaerobic consortium. Rapid perchlorate reduction and bacterial growth were observed up to 1.84gl−1 of perchlorate, but not at 3.82gl−1 due to the toxicity. The specific growth rate of the mixed consortium was 0.1h−1. The consortium co-reduced perchlorate and nitrate with acetate as e− donor and carbon source. The presence of nitrate slowed down the perchlorate reduction rate. The other e− acceptors utilized include oxygen, chlorate, Cr(VI), and selenate. Over 95% of the 16mgl−1 of added Cr(VI) was reduced within 24h of incubation with a high-density perchlorate-grown consortium. However, the consortium failed to couple growth with reduction of nitrite, sulfate, thiosulfate, and sulfite. During the search for autotrophic perchlorate reduction, many consortia from very diverse natural sources could not use sulfur compounds such as thiosulfate as e− donor. [Copyright &y& Elsevier]

Natural chlorate (ClO 3 −) is widely distributed in terrestrial and extraterrestrial environments. To improve understanding of the origins and distribution of ClO 3 −, we developed and tested methods to determine the multi-dimensional isotopic compositions (δ18O, Δ17O, δ37Cl, 36Cl/Cl) of ClO 3 − and then applied the methods to samples of natural nitrate-rich caliche-type salt deposits in the Atacama Desert, Chile, and Death Valley, USA. Tests with reagents and artificial mixed samples indicate stable-isotope ratios were minimally affected by the purification processes. Chlorate extracted from Atacama samples had δ18O = +7.0 to +11.1‰, Δ17O = +5.7 to +6.4‰, δ37Cl = −1.4 to +1.3‰, and 36Cl/Cl = 48 × 10−15 to 104 × 10−15. Chlorate from Death Valley samples had δ18O = −6.9 to +1.6‰, Δ17O = +0.4 to +2.6‰, δ37Cl = +0.8 to +1.0‰, and 36Cl/Cl = 14 × 10−15 to 44 × 10−15. Positive Δ17O values of natural ClO 3 − indicate that its production involved reaction with O 3 , while its Cl isotopic composition is consistent with a tropospheric or near-surface source of Cl. The Δ17O and δ18O values of natural ClO 3 − are positively correlated, as are those of ClO 4 − and NO 3 − from the same localities, possibly indicating variation in the relative contributions of O 3 as a source of O in the formation of the oxyanions. Additional isotopic analyses of ClO 3 − could provide stronger constraints on its production mechanisms and/or post-formational alterations, with applications for environmental forensics, global biogeochemical cycling of Cl, and the origins of oxyanions detected on Mars. • Developed and validated method for purification and isotopic analyses of chlorate. • Natural chlorate isotopic composition is distinct from anthropogenic chlorate. • Natural chlorate from the Atacama and Death Valley have distinct isotopic compositions. • Isotopic compositions of natural chlorate are different from those of coexisting perchlorate. • Natural chlorate is partially formed from reactions with ozone. [ABSTRACT FROM AUTHOR]