Seasonal variation and factors influencing perchlorate in water,snow, soil and corns in Northeastern China

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.     

Influence of soil type and extraction conditions on perchlorate analysis by ion chromatography

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.     

Perchlorate in fish from a contaminated site in east-central Texas

Perchlorate, a known thyroid endocrine disruptor, contaminates surface waters near military instillations where solid fuel rocket motors are manufactured or assembled. To assess potential perchlorate exposure to fish and the human population which may feed on them, fish were collected around the Naval Weapons Industrial Reserve Plant in McLennan County, TX, and analyzed for the presence of the perchlorate anion. The sampling sites included Lake Waco and Belton Lake, and several streams and rivers within their watersheds. The general tendency was that perchlorate was only found in a few species sampled, and perchlorate was not detected in every individual within these species. When detected in the fish, perchlorate tissue concentrations were greater than that in the water. This may be due to highly variable perchlorate concentrations in the water coupled with individual-level variation in elimination from the body, or to routes of exposure other than water.     

Perchlorate: Problems,Detection, and Solutions

The perchlorate anion (ClO 4 m ) is produced when the solid salts of ammonium, potassium, and sodium perchlorate, and perchloric acid dissolve in water. Ammonium perchlorate, used in solid rocket engine fuels, has a limited shelf life and must periodically be replaced. Before 1997, perchlorate could not be readily detected in groundwater at concentrations below 100 µg/L, until the California Department of Health Services developed an acceptable analytical method that lowered the detection limit to 4 µg/L. Subsequently, groundwater containing perchlorate were soon encountered in several western states, and contamination became apparent in Colorado River water. Most perchlorate salts have high water solubilities; concentrated solutions have densities greater than water. Once dissolved, perchlorate is extremely mobile, requiring decades to degrade. Health effects from ingesting low dosage perchlorate-contaminated water are not well known: it interferes with the body's iodine intake, causing an inhibition of human thyroid production. Contaminated surface and groundwater treatment may require bio- and/or phytoremediation technologies. Perchlorate in groundwater is relatively unretarded; it probably travels by advection. Therefore, it may be used as a tracer for hydrocarbon and metal contaminants that are significantly more retarded. Possible forensic techniques include chlorine isotopes for defining multiple or commingled perchlorate plumes.     

Review on Fate,Toxicity, and Remediation of Perchlorate

Several issues regarding the adverse impacts of the chemical—perchlorate—have been identified recently. Perchlorate is a persistent chemical, and remains in water and soil, thereby accumulating in plants and animals. Fetuses suffer the most from perchlorate contamination. There are ongoing debates about the impacts, toxicity and health effects of perchlorate. Many studies have been conducted on its ecotoxicity and its effects, but standards do not exist for perchlorate. This study aims to review the sources, impacts, fate, transport and remediation of perchlorate.     

Determination of perchlorate in selected surface waters in the Great Lakes Basin by HPLC/MS/MS

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 (0.2 microg/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.     

Perchlorate: Problems,Detection, and Solutions

The perchlorate anion (ClO₄^–) is produced when the solid salts of ammonium, potassium, and sodium perchlorate, and perchloric acid dissolve in water. Ammonium perchlorate, used in solid rocket engine fuels, has a limited shelf life and must periodically be replaced. Before 1997, perchlorate could not be readily detected in groundwater at concentrations below 100 μg/L, until the California Department of Health Services developed an acceptable analytical method that lowered the detection limit to 4 μg/L. Subsequently, groundwater containing perchlorate were soon encountered in several western states, and contamination became apparent in Colorado River water. Most perchlorate salts have high water solubilities; concentrated solutions have densities greater than water. Once dissolved, perchlorate is extremely mobile, requiring decades to degrade. Health effects from ingesting low dosage perchlorate-contaminated water are not well known: it interferes with the body's iodine intake, causing an inhibition of human thyroid production. Contaminated surface and groundwater treatment may require bio- and/or phytoremediation technologies. Perchlorate in groundwater is relatively unretarded; it probably travels by advection. Therefore, it may be used as a tracer for hydrocarbon and metal contaminants that are significantly more retarded. Possible forensic techniques include chlorine isotopes for defining multiple or commingled perchlorate plumes.     

Uptake and elimination of perchlorate in eastern mosquitofish

The purpose of this study was to investigate the uptake and elimination of perchlorate in eastern mosquitofish (Gambusia holbrooki). Fish were exposed to 0.1-1000 mg/l sodium perchlorate for 12h, 1, 2, 5, 10, and 30 days, and perchlorate was determined in whole body extracts. Perchlorate was not detected in mosquitofish exposed to the low concentrations of perchlorate (0, 0.1, and 1mg/l sodium perchlorate), regardless of the exposure time, whereas it was detected when fish were exposed to 10, 100, and 1000 mg/l. The tissue concentrations were approximately 10 times less than that in the water. There was no difference in the uptake of perchlorate depending upon the exposure time, however, a difference in perchlorate uptake depending upon the concentration of the exposure dose (P<0.001) was observed. Uptake (K(u)) and elimination (K(e)) rate constants were 0.09 l/mg day and 0.70 day(-1), respectively. The half-life (T1/2) of perchlorate was 0.99 day. Thus, it appears that perchlorate is rapidly taken up and eliminated in eastern mosquitofish. These results are critical and may be used to develop models of fate, effects, and transport of perchlorate in natural systems, as well as to assess ecological risk in affected ecosystems.     

Effects of perchlorate on growth of four wetland plants and its accumulation in plant tissues

Perchlorate contamination in water is of concern because of uncertainties about toxicity and health effects, impact on ecosystems, and possible indirect exposure pathways to humans. Therefore, it is very important to investigate the ecotoxicology of perchlorate and to screen plant species for phytoremediation. Effects of perchlorate (20, 200, and 500 mg/L) on the growth of four wetland plants (Eichhornia crassipes, Acorus calamus L., Thalia dealbata, and Canna indica) as well as its accumulation in different plant tissues were investigated through water culture experiments. Twenty milligrams per liter of perchlorate had no significant effects on height, root length, aboveground part weight, root weight, and oxidizing power of roots of four plants, except A. calamus, and increasing concentrations of perchlorate showed that out of the four wetland plants, only A. calamus had a significant (p?<?0.05) dose-dependent decrease in these parameters. When treated with 500 mg/L perchlorate, these parameters and chlorophyll content in the leaf of plants showed significant decline contrasted to control groups, except the root length of E. crassipes and C. indica. The order of inhibition rates of perchlorate on root length, aboveground part weight and root weight, and oxidizing power of roots was: A. calamus > C. indica > T. dealbata > E. crassipes and on chlorophyll content in the leaf it was: A. calamus > T. dealbata > C. indica > E. crassipes. The higher the concentration of perchlorate used, the higher the amount of perchlorate accumulation in plants. Perchlorate accumulation in aboveground tissues was much higher than that in underground tissues and leaf was the main tissue for perchlorate accumulation. The order of perchlorate accumulation content and the bioconcentration factor in leaf of four plants was: E. crassipes > C. indica > T. dealbata > A. calamus. Therefore, E. crassipes might be an ideal plant with high tolerance ability and accumulation ability for constructing wetland to remediate high levels of perchlorate polluted water.     

Perchlorate as an environmental contaminant

Perchlorate anion (ClO4-) has been found in drinking water supplies throughout the southwestern United States. It is primarily associated with releases of ammonium perchlorate by defense contractors, military operations, and aerospace programs. Ammonium perchlorate is used as a solid oxidant in missile and rocket propulsion systems. Traces of perchlorate are found in Chile saltpeter, but the use of such fertilizer has not been associated with large scale contamination. Although it is a strong oxidant, perchlorate anion is very persistent in the environment due to the high activation energy associated with its reduction. At high enough concentrations, perchlorate can affect thyroid gland functions, where it is mistakenly taken up in place of iodide. A safe daily exposure has not yet been set, but is expected to be released in 2002. Perchlorate is measured in environmental samples primarily by ion chromatography. It can be removed by anion exchange or membrane filtration. It is destroyed by some biological and chemical processes. The environmental occurrence, toxicity, analytical chemistry, and remediative approaches are discussed.     

Aluminum-based drinking-water treatment residuals: a novel sorbent for perchlorate removal

Perchlorate contamination of aquifers and drinking-water supplies has led to stringent regulations in several states to reduce perchlorate concentrations in water at acceptable levels for human consumption. Several perchlorate treatment technologies exist, but there is significant cost associated with their use, and the majority of them are unable to degrade perchlorate to innocuous chloride. We propose the use of a novel sorbent for perchlorate, i.e. an aluminum-based drinking-water treatment residual (Al-WTR), which is a by-product of the drinking-water treatment process. Perchlorate sorption isotherms (23+/-1 degrees C) showed that the greatest amount (65%) of perchlorate removed by the Al-WTR was observed with the lowest initial perchlorate load (10 mg L(-1)) after only 2 h of contact time. Increasing the contact time to 24 h, perchlorate removal increased from 65 to 76%. A significant correlation was observed between the amounts of perchlorate removed with evolved chloride in solution, suggesting degradation of perchlorate to chloride.     

Plant uptake and translocation of air-borne chlordane and comparison with the soil-to-plant route

In order to assess fully the impact of persistent organic pollutants (POPs) on human health, pollutant exchange at the interface between terrestrial plants, in particular food crops, and other environmental compartments must be thoroughly understood. In this regard, transfers of multicomponent and chiral pollutants are particularly informative. In the present study, zucchini (Cucurbita pepo L.) was planted in containerized, uncontaminated soil under both greenhouse and field conditions and exposed to air-borne chlordane contamination at 14.0 and 0.20 ng/m(3) (average, greenhouses), and 2.2 ng/m(3) (average, field). Chiral gas chromatography interfaced to an ion trap mass spectrometer was used to determine the chiral (trans-chlordane, TC, and cis-chlordane, CC) and achiral (trans-nonachlor, TN) chlordane components in vegetation, air, and soil compartments. The chlordane components of interest were detected in all vegetation tissues examined--root, stem, leaves, and fruits. When compared with the data from a soil-to-plant uptake study, the compositional profile of the chlordane components, i.e. the component fractions of TC, CC, and TN, in plant tissues, showed significantly different patterns between the air-to-plant and soil-to-plant pathways. Changes in the enantiomer fractions of TC and CC in plant tissues relative to the source, i.e. air or soil, although observed, were not markedly different between the two routes. This report provides the first comprehensive comparison between two distinct plant uptake routes for POPs and their subsequent translocation within plant tissues.     

Microbial processes in the rhizosphere soil of a heavy metals-contaminated Mediterranean salt marsh: a facilitating role of AM fungi

We investigated the relationship of the zonal pattern followed by the vegetation in a polluted Mediterranean salt marsh, in semiarid south-eastern Spain, with the microbiological and biochemical properties (labile C fractions, oxidoreductases and hydrolases) of the rhizosphere soil of two halophyte species, Arthrocnemum macrostachyum and Sarcocornia fruticosa, and with the degree of arbuscular mycorrhizal (AM) colonisation in their rhizospheres. Levels of plant biomass and cover were inversely related to heavy metal contents and salinity. The concentrations of Fe, Cu, Mn and Pb extracted with DTPA hardly varied among the different zones of the salt marsh. The dehydrogenase and phosphatase activities, the soluble C and water-soluble carbohydrates concentrations and the extent of root colonisation were greater in the salt marsh zones of lower soil salinity and lower metal concentration. Urease and beta-glucosidase activities were not detected in the salt marsh. Plant biomass and cover showed positive relationships with mycorrhizal colonisation (R=0.773, P<0.001; R=0.874, P<0.001, respectively). Mycorrhizal colonisation was negatively correlated with the contents of Pb and Zn in plant tissues. This work supports the view that reduced plant uptake of toxic metals, particularly lead, could be involved in the beneficial effects of AM fungi on plant development in Mediterranean salt marshes contaminated with mining wastes.     

Occurrence of perchlorate in rice from different areas in the Republic of Korea

Perchlorate concentrations in rice samples from many different provinces, and correlation with surface water contamination, were investigated in the Republic of Korea. Perchlorate levels in the 51 rice samples purchased from local markets ranged from below the detection limit to 1.79?±?0.39 μg/kg with a mean level of 0.21 μg/kg and 7 samples collected from the Nakdong River watershed ranged from 0.38?±?0.1 to 3.23?±?0.47 μg/kg with a mean level of 0.9 μg/kg. The correlation coefficient between perchlorate levels in rice samples from the Nakdong river watershed and the levels in surface water was estimated to be approximately 0.904 in the 95 % confidence interval. These results show that surface water contamination was highly related to the perchlorate pollution of rice in the Republic of Korea.     

Behaviour of alpha-, beta-, gamma-, and delta-hexachlorocyclohexane in the soil-plant system of a contaminated site

The behaviour of the organochlorine pesticide hexachlorocyclohexane (HCH) is investigated. The concentrations of alpha-, beta-, gamma-, and delta-HCH isomers were measured in soils, rhizosphere and vegetation in a contaminated area in Galicia (NW Spain). The total concentration of HCH in soils reached values close to 20,000 mgkg(-1). The plants analysed (Avena sativa L., Chenopodium spp., Solanum nigrum L., Cytisus striatus (Hill) Roth, and Vicia sativa L.) accumulated HCH, especially the beta-HCH isomer, in their tissues. The most likely mechanisms of HCH accumulation in plants were sorption of soil HCH on roots and sorption of volatilized HCH on aerial plant tissues. The concentrations of HCH obtained from the bulk and rhizosphere soils of selected plant species suggest that roots tend to reduce levels of the HCH isomers in the rhizosphere. The results reflect the importance of vegetation in the distribution of organochlorine compounds in the soil-plant system.     

Comparison of biotic and abiotic treatment approaches for co-mingled perchlorate, nitrate, and nitramine explosives in groundwater

Biological and abiotic approaches for treating co-mingled perchlorate, nitrate, and nitramine explosives in groundwater were compared in microcosm and column studies. In microcosms, microscale zero-valent iron (mZVI), nanoscale zero-valent iron (nZVI), and nickel catalyzed the reduction of RDX and HMX from initial concentrations of 9 and 1 mg/L, respectively, to below detection (0.02 mg/L), within 2 h. The mZVI and nZVI also degraded nitrate (3 mg/L) to below 0.4 mg/L, but none of the metal catalysts were observed to appreciably reduce perchlorate ( approximately 5 mg/L) in microcosms. Perchlorate losses were observed after approximately 2 months in columns of aquifer solids treated with mZVI, but this decline appears to be the result of biodegradation rather than abiotic reduction. An emulsified vegetable oil substrate was observed to effectively promote the biological reduction of nitrate, RDX and perchlorate in microcosms, and all four target contaminants in the flow-through columns. Nitrate and perchlorate were biodegraded most rapidly, followed by RDX and then HMX, although the rates of biological reduction for the nitramine explosives were appreciably slower than observed for mZVI or nickel. A model was developed to compare contaminant degradation mechanisms and rates between the biotic and abiotic treatments.     

中国高氯酸盐污染现状及去除技术研究进展

高氯酸盐是广泛存在于水体环境中的具有高稳定性、高扩散性和持久性的内分泌干扰物,其毒理机制、环境污染、迁移转化和处理技术已成为目前环保领域的研究热点.简要介绍了高氯酸盐的特性、来源及对人体的危害,对比了国内外不同地区高氯酸盐的污染状况,综述了中国已开展的高氯酸盐处理技术,为高氯酸盐环境污染问题的研究提供参考.     

Effects of EDTA on solubility of cadmium, zinc, and lead and their uptake by rainbow pink and vetiver grass

Rainbow pink (Dianthus chinensis), a potential phytoextraction plant, can accumulate high concentrations of Cd from contaminated soils. Vetiver grass (Vetiver zizanioides) has strong and long root tissues and is a potential phytostabilization plant since it can tolerate and grow well in soils contaminated with multiple heavy metals. Soil was moderately artificially contaminated by cadmium (20 mg/kg), zinc (500 mg/kg), and lead (1000 mg/kg) in pot experiments. Three concentrations of Na2-EDTA solution (0, 5, and 10 mmol/kg soil) were added to the contaminated soils to study the influence of EDTA solution on phytoextraction by rainbow pink or phytostabilization by vetiver grass. The results showed that the concentrations of Cd, Zn, and Pb in a soil solution of rainbow pink significantly increased following the addition of EDTA (p < 0.05). The concentrations of Cd and Pb in the shoots of rainbow pink also significantly increased after EDTA solution was applied (p < 0.05), but the increase for Zn was insignificant. EDTA treatment significantly increased the total uptake of Pb in the shoot, over that obtained with the control treatment (p < 0.001), but it did not significantly increase the total uptake of Cd and Zn. The concentrations of Zn and Pb in the shoots of rainbow pink are significantly correlated with those in the soil solution, but no relationship exists with concentrations in vetiver grass. The toxicity of highly contaminating metals did not affect the growth of vetiver grass, which was found to grow very well in this study. Results of this study indicate that rainbow pink can be considered to be a potential phytoextraction plant for removing Cd or Zn from metal-contaminated soils, and that vetiver grass can be regarded as a potential phytostabilization plant that can be grown in a site contaminated with multiple heavy metals.     

Plant uptake, accumulation and translocation of phenanthrene and pyrene in soils

Uptake, accumulation and translocation of phenanthrene and pyrene by 12 plant species grown in various treated soils were comparatively investigated. Plant uptake and accumulation of phenanthrene and pyrene were correlated with their soil concentrations and plant compositions. Root or shoot accumulation of phenanthrene and pyrene in contaminated soils was elevated with the increase of their soil concentrations. Significantly positive correlations were shown between root concentrations or root concentration factors (RCFs) of phenanthrene and pyrene and root lipid contents. The RCFs of phenanthrene and pyrene for plants grown in contaminated soils with initial phenanthrene concentration of 133 mgkg(-1) and pyrene of 172 mgkg(-1) were 0.05-0.67 and 0.23-4.44, whereas the shoot concentration factors of these compounds were 0.006-0.12 and 0.004-0.12, respectively. For the same soil-plant treatment, shoot concentrations and concentration factors of phenanthrene and pyrene were generally much lower than root. Translocations of phenanthrene and pyrene from shoots to roots were undetectable. However, transport of these compounds from roots to shoots usually was the major pathway of shoot accumulation. Plant off-take of phenanthrene and pyrene only accounted for less than 0.01% of dissipation enhancement for phenanthrene and 0.24% for pyrene in planted versus unplanted control soils, whereas plant-promoted biodegradation was the predominant contribution of remediation enhancement of soil phenanthrene and pyrene in the presence of vegetation.     

Tracking chlordane compositional and chiral profiles in soil and vegetation

The cycling of chlordane and other persistent organic pollutants through the environment must be comprehensively elucidated to assess adequately the human health risks posed from such contaminants. In this study the compositional and chiral profiles of weathered chlordane residues in the soil and vegetative compartments were investigated in order to provide details of the fate and transport of this persistent pesticide. Zucchini was planted in a greenhouse in three bays containing chlordane-contaminated soil. At harvest the vegetation and soil were extracted and analyzed for chlordane content using chiral gas chromatography/ion trap mass spectrometry. Both achiral and chiral chlordane components were quantified. The chlordane concentration in the rhizosphere (soil attached to roots) was significantly less than that in the bulk soil. However, the enantiomeric ratio of the chiral components and overall component ratios had changed little in the rhizosphere relative to the bulk soil. Significant levels of chlordane were detected in the vegetation, the amount varying in different plant tissues from a maximum in roots to a minimum in fruit. In addition to the chlordane concentration gradient in plant tissues, significant shifts in compositional profile, as indicated by the component ratios, and in chiral profile, as indicated by the enantiomeric ratio, of the contaminant were observed in the plant tissues. The data indicate that abiotic processes dominate the transport of the chlordane components through the soil to the plant. This is the first report of the effect of rapid biotic processes within the plant compartment on chlordane compositional and chiral profiles.