Abstract  Desorption of rare-earth metals (REMs) (lanthanum, yttrium, and ytterbium), as well as iron and aluminum, from the KU-2 sulfocation exchanger phase with solutions of mineral acids and ammonium nitrate and sulfate of various concentrations was studied. New data on the distribution of REMs in these systems were obtained. It was found that it is the most rational to use an ammonium nitrate solution with concentration of 300 g L-1. It is recommended to precipitate a concentrate of REMs from the resulting desorbate with ammonium carbonate, with the subsequent separation of the suspension by the electrofl otation method.

Abstract  For solid oxide fuel cell electrode material, calcium doped lanthanum manganite La0.4Ca0.6MnO3 (LCMO) and cerium-incorporated on Ca-site with composition La0.40Ca0.55Ce0.05MnO3 (LCCMO) were synthesized using most feasible and efficient glycine-nitrate method. The formation of crystalline single phase was confirmed by x-ray diffraction (XRD). The Rietveld analysis reveals that both systems crystallize into orthorhombic crystal structure with Pnma space group. Additionally, 8 mole % Y2O3 stabilized ZrO2 (8YSZ) solid electrolyte was also synthesized using high energy ball mill to check the reaction with electrode materials. It was found that the substitution of Ce+4 cations in LCMO perovskite suppressed formation of undesired insulating CaZrO3 phase.

Abstract  By pot experiment method, this study investigated the role of plant hormone abscisic acid (ABA) in the foliar application of 10 mu M lanthanum nitrate (La(NO3)(3))-regulated the biosynthesis, regeneration and degradation of vitamin C (Vc) and the content of Vc in the fruit of strawberry at different periods of growth and development. The results showed that La(NO3)(3) significantly increased the content of Vc by increasingthe activities of recycling enzymes glutathione reductase (GR), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) and biosynthetic enzyme L-galactono-1,4-lactone dehydrogenase (GaILDH), and decreasing the activities of recycling enzyme APX and degrading enzyme ascorbic acid oxidase (AAO). Compared with La (NO3)(3) alone, applications of different ABA biosynthesis inhibitor sodium tungstate (Tu) all markedly decreased the activities of GR, MDHAR and GaILDH, and increased the activities of DHAR and APX, which resulted in the reduction in the content of Vc. Meanwhile, La(NO3)(3) induced the production of ABA and Tu reversed the effect of La(NO3)(3) on ABA content. Our results suggested that La(NO3)(3)-induced ABA participated in the regulation of Vc content in the fruit of strawberry.

Abstract  Our study aimed to elucidate the plant growth-promoting characteristics and the structure and composition of Sphingomonas sp. LK11 genome using the single molecule real-time (SMRT) sequencing technology of Pacific Biosciences. The results revealed that LK11 produces different types of gibberellins (GAs) in pure culture and significantly improves soybean plant growth by influencing endogenous GAs compared with non-inoculated control plants. Detailed genomic analyses revealed that the Sphingomonas sp. LK11 genome consists of a circular chromosome (3.78 Mbp; 66.2% G+C content) and two circular plasmids (122,975 bps and 34,160 bps; 63 and 65% G+C content, respectively). Annotation showed that the LK11 genome consists of 3656 protein-coding genes, 59 tRNAs, and 4 complete rRNA operons. Functional analyses predicted that LK11 encodes genes for phosphate solubilization and nitrate/nitrite ammonification, which are beneficial for promoting plant growth. Genes for production of catalases, superoxide dismutase, and peroxidases that confer resistance to oxidative stress in plants were also identified in LK11. Moreover, genes for trehalose and glycine betaine biosynthesis were also found in LK11 genome. Similarly, Sphingomonas spp. analysis revealed an open pan-genome and a total of 8507 genes were identified in the Sphingomonas spp. pan-genome and about 1356 orthologous genes were found to comprise the core genome. However, the number of genomes analyzed was not enough to describe complete gene sets. Our findings indicated that the genetic makeup of Sphingomonas sp. LK11 can be utilized as an eco-friendly bioresource for cleaning contaminated sites and promoting growth of plants confronted with environmental perturbations.

Abstract  Carbon fiber-reinforced polymers (CFRPs) are structural composites used in the aerospace and sporting goods industries. Their chief appeal lies in their high specific properties, which generally outperform metallic counterparts. There is a contemporary need for viable methods for recycling CRFPs at the end of their lifecycles and for utilizing the considerable production waste (ca. 30%) of CFRP part manufacturing. The cost associated with these waste streams is a principal economic driver inhibiting the penetration of CRFPs into larger-scale manufacturing, particularly in the automotive industry. Reported techniques for CRFP degradation involve pyrolysis or mechanical grinding of the CFRP, processes Ph which are outlawed in some jurisdictions and can reduce the thermomechanical properties of the recycled products. In this study, we report a conceptually different approach to degrading a commercial blended benzoxazine/epoxy resin under mild, oxidative conditions. The thermosetting resin is polymerized, characterized, and then catalytically depolymerized via hydride abstraction with a ruthenium catalyst. These results demonstrate a concept for sustainable recycling of CFRP composites.

Abstract  The promotion of Ce-doped V/WTi for NH3-SCR performance and ammonium bisulfate (ABS) resistance is fully illustrated. The V2O5/CeO2/WTi-2 presents an excellent NOx conversion at 280 degrees C in the presence of 1000 ppm SO2. The introduction of ceria contributes to the vanadia species agglomeration into the oligomeric V-O-V structures and tight connects with the adjacent vanadium species to form the redox structure of Ce4+-O-Ce3+-O-V5+-O-V5+-O-Ce3+-O-Ce4+, which facilitates the electronic conduction between ceria and vanadia species. The electronic interaction via the redox structure promotes the activation of ammonia adsorbed on vanadia and nitrate species on ceria, which lowers the apparent activation energies (Ea) and significantly improves the NOx conversion rate. The addition of ceria protects active V sites poisoning and improves the stability of the adsorbed NOx species, which prevents VOSO4 formation and competitively inhibits the adsorption of SO2 with less metal sulfate formation on ceria. In addition, the electrons donating from vanadia to ceria species via the redox structure could make ceria species existing in electron enrichment state and boost the electrons around ceria deviating towards sulfates and strengthen the bonding between ceria and as-formed ABS species, which weakens the stability of ABS and promotes to initiate NH3-SCR reaction between the NH4+ species of ABS and NO + O-2. The faster NH3-SCR conversion rate promoted by the redox structure further suppresses the competitive reaction between sulfate and ammonia species, which results in no ABS formation over V/Ce/WTi-2.

Abstract  Nitrogen fixation is a microbial-mediated process converting atmospheric dinitrogen gas to biologically available ammonia or other molecules, and it plays an important role in regulating nitrogen budgets in coastal marine ecosystems. In this study, nitrogen fixation in the intertidal sediments of the Yangtze Estuary was investigated using nitrogen isotope tracing technique. The abundance of nitrogen fixation functional gene (nifH) was also quantified. The measured rates of sediment nitrogen fixation ranged from 0.37 to 7.91nmolNg(-1)hr(-1), while the abundance of nifH gene varied from 2.28x10(6) to 1.28x10(8)copiesg(-1) in the study area. The benthic nitrogen fixation was correlated closely to the abundance of nifH gene and was affected significantly by salinity, pH, and availability of sediment organic carbon and ammonium. It is estimated that sediment nitrogen fixation contributed approximately 9.3% of the total terrigenous inorganic nitrogen transported annually into the Yangtze estuarine and coastal environment. This result implies that the occurrence of benthic nitrogen fixation acts as an important internal source of reactive nitrogen and to some extent exacerbates nitrogen pollution in this aquatic ecosystem.

Abstract  Simultaneous anammox-denitrification process is capable of complete nitrogen removal. To acquire a suitable influent (NO2--N/NH4+-N > 1.32) for it, the wastewater could be treated by partially oxidizing ammonium to nitrite. Although many studies regarding partial nitritation in treating high ammonium wastewater have been reported, very little research has been undertaken on real domestic wastewater for long term. This study presents a partial nitritation-sequencing batch reactor (PN-SBR) to treat domestic wastewater with low SCOD/TN ratios (2.3 +/- 0.6). During the 600 days' operation, the NO2--N/NH4+-N ratios in the effluent mostly varied between 1.32 and 10.07 and thus, stable partial nitritation was maintained. Moreover, during each PN-SBR cycle, similar to 47.6% of organics in raw wastewater were efficiently utilized for denitrifying nitrite, by which the aeration for the oxidation of organic matters was decreased, and stable nitritation was further assured due to the lack of substrate for nitrite oxidizing bacteria. High-throughput sequencing analysis revealed that the dominant nitrifying bacteria were Nitrosomonas belonging to ammonia oxidizing bacteria, while no nitrite oxidizing bacteria were detected. During the idle period of a PN-SBR cycle, the obvious nitrite decrease without observed COD consumption might be due to the predominance of Ottowia, which functioned in fermentation and denitrification, for which nitrite was denitrified by using readily biodegradable organic matters biodegraded by Ottowia bacteria.

Abstract  The "Campaign on Atmospheric Aerosol Research" network of China (CARE-China) is a long-term project for the study of the spatio-temporal distributions of physical aerosol characteristics as well as the chemical components and optical properties of aerosols over China. This study presents the first long-term data sets from this project, including 3 years of observations of online PM2.5 mass concentrations (2012-2014) and 1 year of observations of PM2.5 compositions (2012-2013) from the CARE-China network. The average PM2.5 concentration at 20 urban sites is 73.2 mu g m(-3) (16.8-126.9 mu g m(-3), which was 3 times higher than the average value from the 12 background sites (11.2-46.5 mu g m(-3). The PM2.5 concentrations are generally higher in east-central China than in the other parts of the country due to their relatively large particulate matter (PM) emissions and the unfavourable meteorological conditions for pollution dispersion. A distinct seasonal variability in PM2.5 is observed, with highs in the winter and lows during the summer at urban sites. Inconsistent seasonal trends were observed at the background sites. Bi-modal and unimodal diurnal variation patterns were identified at both urban and background sites. The chemical compositions of PM2.5 were analysed at six paired urban and background sites located within the most polluted urban agglomerations - North China Plain (NCP), Yangtze River delta (YRD), Pearl River delta (PRD), North-east China region (NECR), South-west China region (SWCR) - and the cleanest region of China - the Tibetan Autonomous Region (TAR). The major PM2.5 constituents across all the urban sites are organic matter (OM, 26.0 %), SO42- (17.7 %), mineral dust (11.8 %), NO3- (9.8 %), NH4+(6.6 %), elemental carbon (EC) (6.0 %), Cl- (1.2 %) at 45% RH and unaccounted matter (20.7 %). Similar chemical compositions of PM2.5 were observed at background sites but were associated with higher fractions of OM (33.2 %) and lower fractions of NO3- (8.6 %) and EC (4.1 %). Significant variations of the chemical species were observed among the sites. At the urban sites, the OM ranged from 12.6 mu g m(-3) (Lhasa) to 23.3 mu g m(-3) (Shenyang), the SO42- ranged from 0.8 mu g m(-3) (Lhasa) to 19.7 mu g m(-3) (Chongqing), the NO3- ranged from 0.5 mu g m(-3) (Lhasa) to 11.9 mu g m(-3) (Shanghai) and the EC ranged from 1.4 mu g m(-3) (Lhasa) to 7.1 mu g m(-3) (Guangzhou). The PM2.5 chemical species at the background sites exhibited larger spatial heterogeneities than those at urban sites, suggesting different contributions from regional anthropogenic or natural emissions and from long-range transport to background areas. Notable seasonal variations of PM2.5-polluted days were observed, especially for the megacities in east-central China, resulting in frequent heavy pollution episodes occurring during the winter. The evolution of the PM2.5 chemical compositions on polluted days was consistent for the urban and nearby background sites, where the sum of sulfate, nitrate and ammonia typically constituted much higher fractions (31-57 %) of PM2.5

mass, suggesting fine-particle pollution in the most polluted areas of China assumes a regional tendency, and the importance of addressing the emission reduction of secondary aerosol precursors including SO2 and NOx. Furthermore, distinct differences in the evolution of [NO3-] = [SO42] ratio and OC/EC ratio on polluted days imply that mobile sources and stationary (coal combustion) sources are likely more important in Guangzhou and Shenyang, respectively, whereas in Beijing it is mobile emission and residential sources. As for Chongqing, the higher oxidation capacity than the other three cities suggested it should pay more attention to the emission reduction of secondary aerosol precursors. This analysis reveals the spatial and seasonal variabilities of the urban and background aerosol concentrations on a national scale and provides insights into their sources, processes and lifetimes.

Abstract  Extensive amounts of organic and inorganic substances are discharged into the environment, and they have been ascribed to a number of anthropogenic activities including agriculture, industry, and domestic processes. Microalgae, as a promising alternative feedstock for bioenergy production, have advantages in the uptake of nutrients from wastewater for biomass production. This study assessed the feasibility of mass cultivation of microalgae in controlled environment tertiary treated municipal wastewater. Dunaliella salina (Dsalina) was selected for its high beta carotene generation capacity and being a halophilic species to protect our freshwater resources further in wastewater remediation. Nutrient analyses indicated that Dsalina can significantly remove nitrate, ammonia, and phosphorus from municipal wastewater in the range of 45% to 88%. Among all combinations studied, the optimal algal growth was observed at 30 ppt salinity level, with a 75% wastewater concentration (3:1 ratio of wastewater and saline water mixturethe - the growth medium). The findings concluded that Dsalina has great capacity for nutrient uptake while providing high-value bioproducts. It can therefore be recommended as a potential candidate species that could be used in wastewater treatment systems coupled with high-value bioproducts production.

Abstract  Ulexite is one of the boron minerals, which include a respectable amount of hydration water. It can be used as a raw material in the production of boron compounds. Some part of water in the composition of ulexite can be removed from the solid matrix applying dehydration treatment, and a porous structure can be obtained to increase the reaction rate. In the present study, the effect of dehydration temperature on dissolution kinetics of ulexite in ammonium sulfate solutions was researched in a batch reactor utilizing the parameters of solution concentration, solid-to-liquid ratio, stirring speed and reaction temperature. It was determined that the dissolution rate of calcined material increased with increasing solution concentration and reaction temperature and with decreasing solid-to-liquid ratio. The highest dissolution rate was attained with the sample calcined at 150 degrees C. It was found that the dissolution rate fit to the first order pseudo-homogeneous model. The activation energy of the dissolution process was estimated to be 42 kJ.mol(-1).

Abstract  This review aims at holistically analyzing the environmental problems associated with nitrous oxide (N2O) emissions by evaluating the most important sources of N2O and its environmental impacts. Emissions from wastewater treatment processes and the industrial production of nitric and adipic acid represent nowadays the most important anthropogenic point sources of N2O. Therefore, state-of-the-art strategies to mitigate the generation and release to the atmosphere of this greenhouse and O3-depleting gas in the waste treatment and industrial sectors are also reviewed. An updated review of the end-of-the-pipe technologies for N2O abatement, both in the waste treatment and industrial sectors, is herein presented and critically discussed for the first time. Despite the consistent efforts recently conducted in the development of cost-efficient and eco-friendly N2O abatement technologies, physical/chemical technologies still constitute the most popular treatments for the control of industrial N2O emissions at commercial scale. The recent advances achieved on biological N2O abatement based on heterotrophic denitrification have opened new opportunities for the development of eco-friendly alternatives for the treatment of N2O emissions. Finally, the main limitations and challenges faced by these novel N2O abatement biotechnologies are identified in order to pave the way for market implementation.

Abstract  Groundwater pollution is a serious worldwide concern. Aromatic compounds, chlorinated hydrocarbons, metals and nutrients among others can be widely found in different aquifers all over the world. However, there is a lack of sustainable technologies able to treat these kinds of compounds. Microbial electro-remediation, by the means of microbial electrochemical technologies (MET), can become a promising alternative in the near future. MET can be applied for groundwater treatment in situ or ex situ, as well as for monitoring the chemical state or the microbiological activity. This document reviews the current knowledge achieved on microbial electro-remediation of groundwater and its applications.

Abstract  The completely autotrophic nitrogen removal over nitrite (CANON) process is an important component of energy self-sufficient sewage treatment plants, and the use of aerobic granular sludge is a profitable choice for the CANON process. In this study, the performance and microbial characteristics of CANON granular sludge were investigated for treating synthetic and mainstream domestic sewage. The average nitrogen removal rate (NRR) was 3.22 kg Nm(-3) d(-1) during the high-rate operating period with high MLSS (4.09 g L-1) and DO (similar to 1.0 mg L-1) for treating synthetic sewage. When the influent was mainstream sewage, the average NRR was 1.11 kg Nm(-3) d(-1). The effluent nitrate concentration was very low, and nitrate build-up was not found. High-throughput pyrosequencing results indicated that, Nitrosomonas and Candidatus Brocadia were the dominant genus in ammonia oxidizing bacteria (AOB) and anaerobic AOB (AAOB), respectively. The proportions of AOB and AAOB decreased during mainstream sewage treatment, but the reactor maintained good performance. The results confirmed the feasibility of using CANON granular sludge for treating mainstream sewage.

Abstract  In this study, an electrochemical-adsorption (ECA) system was constructed by packing iron particles and zeolites between electrodes to simultaneously remove nitrate and its by-products without excessive active chloride accumulation. Response surface methodology (RSM) with Box-Behnken design (BBD) was applied to investigate the effects of independent variables (iron particle, zeolite and current density) and their interaction on the system performance, also determining its optimum working state. The optimal conditions for the amount of iron particles (19.74g) and zeolites (28.19g) as well as the current density (18.72 mA/cm(2)) resulted in a high nitrate removal efficiency of 95% and merely a little ammonia accumulation. Polarized iron particles could provide more reactive sites and increase mass transfer efficiency, thus promoted nitrate reduction and decreased energy consumption. Synergistic effects of electrolysis and zeolite adsorption accelerated ammonium removal by increasing the rate of ion directional migration. The system having low operation costs and no secondary pollution appeared to be an advisable enhancing strategy for removing nitrate and by-products. (C) 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Abstract  Pastoral agriculture is a major source for nitrate (contamination in surface and ground waters and for the greenhouse gas emissions in New Zealand. Advances have been made in recent years in understanding the role of different ammonia oxidisers, including ammonia oxidising bacteria (AOB) and ammonia oxidising archaea (AOA) in nitrification, and in developing nitrification inhibitor (NI) mitigation technologies. Results showed that, in the N-rich soil environment under the animal urine patches in grazed grassland, AOB are the dominant microbes responsible for ammonia oxidation whereas AOA play a less important role. A number of laboratory and field studies have demonstrated conclusively that treating grazed pasture soils with a nitrification inhibitor (NI), such as dicyandiamide (DCD), which inhibits the growth and activity of AOB, is an effective means of reducing NO3- leaching and N2O emissions.

Abstract  A series of dealuminated ZSM-5 zeolite (deAlZSM-5) supported Fe-based catalysts are prepared by a modified solid-state ion exchange method, in which the HZSM-5 zeolite is dealuminated by concentrated HNO3 and subsequently ground with ferric nitrate. The physicochemical properties of the resultant Fe/deAlZSM-5 catalysts are characterized by XRD, N-2 sorption, TEM, H-2-TPR and NH3-TPD techniques. It is revealed that the Fe species are highly dispersed in the deAlZSM-5, and would be transformed into elemental Fe nanoparticles after reduction by H-2. Due to the confinement effect of ZSM-5 zeolite, the Fe/deAlZSM-5 catalysts exhibit high catalytic activity and excellent stability for NH3 decomposition. At 650 degrees C, about 100% NH3 conversion can be achieved over the 9%Fe/deAlZSM-5 catalysts for 50 h time-on-stream, demonstrating a very promising catalyst system in NH3 decomposition.

Abstract  In this work, a nanocarbon bridged nanomagnetite network (NC-NMN) is developed through the electrospinning of epichlorohydrin functionalized polystyrene (f-PS), followed by the direct calcination of f-PS and ferric nitrate, which is capable of superfast removing hexavalent chromium (Cr(VI)) from polluted water within only 15 s benefiting from its gridding framework, with an adsorption rate constant of 1.64 g mg-1 min-1 according to the pseudo-second-order kinetics. The well-fitted Langmuir isotherm model indicates a monolayer adsorption for Cr(VI) on NC-NMN. The thermodynamic parameters including negative ΔG° and positive ΔH° demonstrate that the Cr(VI) adsorption on NC-NMN is spontaneous and endothermic. The Cr(VI) adsorption retention, which is only 3.8%, is achieved for NC-NMN after five cycles, exhibiting a prominent stability and an excellent recyclability. X-ray photoelectron spectroscopy (XPS), zeta potential and energy-filter transmission electron spectroscopy (EFTEM) results illustrate that both the electrostatic attraction and the network structure of NC-NMN are responsible for the superior Cr(VI) adsorption performance. This work intends to provide a new method for designing the novel structure materials for polluted water treatment.

Abstract  Phenylalanine ammonia-lyase (PAL) is one of the principle enzymes involved in plant's secondary metabolism. Expression of individual isogene from the PAL gene family is variable with species of plants in responses to different stresses. In this study, transcriptome analysis of the PAL gene family in rice seedlings exposed to potassium chromate Cr(VI) or chromium nitrate Cr(III) was conducted using Agilent 44K rice microarray and real-time quantitative RT-PCR. Uptake and accumulation of both Cr species by rice seedlings and their effect on PAL activity were also determined. Three days of Cr exposure led to significant accumulation of Cr in plant tissues, but majority being in roots rather than shoots. Changes of PAL activities in rice tissues were evident from both Cr treatments. Individual isogene from the rice PAL gene family was expressed differentially in response to both Cr variants. Comparing gene expression between two Cr treatments, only osPAL2 and osPAL4 genes were expressed in similar patterns. Also, gene expression pattern was inconsistent in both plant tissues. Results indicated that expression of individual isoform from the rice PAL gene family is tissue, and stimulus specific under different Cr exposure, suggesting their different detoxification strategies for decreasing or eliminating Cr stresses.

Abstract  Forest declines have been reported with increasing regularity during the last decade and are expected to increase due to the ongoing environmental changes. During adverse environmental conditions, plant symbioses with mycorrhizas can help to reduce plant stress. Mycorrhizas are symbiotic associations between fungi and roots of living plants. Plants offer carbohydrates to the fungus and the fungus improves the acquisition of nutrients and water to the plant. Specifically, arbuscular mycorrhizal (AM) fungi are the most abundant mycorrhizas. In South Africa, there are increasing reports describing the decline of native Euphorbia ingens trees. This study analysed the presence and abundance of AM fungal colonisation in the roots of E. ingens trees, and the number of AM fungal spores in the surrounding soil, with the aim to improve the understanding of the rapid decline of these trees. AM fungal colonisation and spores in relation to the soil properties were also analysed. Soil and root samples were collected from different rates of declining E. ingens trees at three sites in South Africa. AM fungal colonisation of the roots was assessed and fungal spores in the surrounding soil were enumerated. Soil phosphorus, mineral nitrogen and pH were analysed from the soil samples. The results showed that AM fungi are associated with E. ingens trees. AM abundance was influenced by site specific properties and not by E. ingens health. Moreover, the level of soil NO3- and soil texture significantly influenced AM colonisation in roots and the number of spores enumerated. These preliminary findings provide background information for further research into the large-scale decline of E. ingens populations in South Africa. (c) 2017 SAAB. Published by Elsevier B.V. All rights reserved.

Abstract  Total dissolved solids (TDS) concentrations in groundwater tapped for beneficial uses (drinking water, irrigation, freshwater industrial) have increased on average by about 100 mg/L over the last 100 years in the San Joaquin Valley, California (SJV). During this period land use in the SJV changed from natural vegetation and dryland agriculture to dominantly irrigated agriculture with growing urban areas. Century-scale salinity trends were evaluated by comparing TDS concentrations and major ion compositions of groundwater from wells sampled in 1910 (Historic) to data from wells sampled in 1993-2015 (Modern). TDS concentrations in subregions of the SJV, the southern (SSJV), western (WSJV), northeastern (NESJV), and southeastern (SESJV) were calculated using a cell-declustering method. TDS concentrations increased in all regions, with the greatest increases found in the SSJV and SESJV. Evaluation of the Modern data from the NESJV and SESJV found higher TDS concentrations in recently recharged (post-1950) groundwater from shallow (<50 m) wells surrounded predominantly by agricultural land uses, while premodern (pre-1950) groundwater from deeper wells, and recently recharged groundwater from wells surrounded by mainly urban, natural, and mixed land uses had lower TDS concentrations, approaching the TDS concentrations in the Historic groundwater. For the NESJV and SESJV, inverse geochemical modeling with PHREEQC indicated that weathering of primary silicate minerals accounted for the majority of the increase in TDS concentrations, contributing more than nitrate from fertilizers and sulfate from soil amendments combined. Bicarbonate showed the greatest increase among major ions, resulting from enhanced silicate weathering due to recharge of irrigation water enriched in CO2 during the growing season. The results of this study demonstrate that large anthropogenic changes to the hydrologic regime, like massive development of irrigated agriculture in semi-arid areas like the SJV, can cause large changes in groundwater quality on a regional scale.

Abstract  Constructed wetlands (CWs) have been used globally in wastewater treatment for years. CWs represent an efficient ecological system which is both energy-saving and low in investment for construction and operational cost. In addition, CWs also have the advantage of being easy to operate and maintain. However, the operation of CWs at northern latitudes (both mid and high) is sometimes quite demanding, due to the inhibitory effect of low temperatures that often occur in winter. To evaluate the wastewater treatment performance of a culture of mixed Psychrotrophic bacteria strains in an integrated vertical-flow CW, the removal rates of ammonia nitrogen (NH3-N), chemical oxygen demand (COD), nitrite nitrogen [Formula: see text], nitrate nitrogen [Formula: see text] and total phosphorus (TP) were quantified at different bacterial dosages to determine the best bacterial dosage and establish kinetic degradation models of the mixed strains. The bacterial culture was made up of Psychrobacter TM-1, Sphingobacterium TM-2 and Pseudomonas TM-3, mixed together at a volume/volume ratio of 1 : 1 : 1 (at bacterial suspension concentrations of 4.4 × 109 ml-1). Results showed that the organic pollutants (nitrogen and phosphorus) in the sewage could be efficiently removed by the culture of mixed Psychrotrophic bacteria. The optimal dosage of this mixed bacteria strain was 2.5%, and the treatment efficiency of COD, NH3-N, [Formula: see text], [Formula: see text], total nitrogen and TP were stable at 91.8%, 91.1%, 88.0%, 93.8%, 94.8% and 95.2%, respectively, which were 1.5, 2.0, 2.1, 1.5, 2.2 and 1.3 times those of the control group. In addition, a pseudo-first-order degradation model was a good fit for the degradation pattern observed for each of these pollutants.

Abstract  In the present study, the role of sulfur (K2SO4: S; 60 mg S kg-1 sand) and/or calcium (CaCl2: Ca; 250 mg Ca kg-1 sand) applied alone as well as in combination on growth, photosynthetic performance, indices of chlorophyll a fluorescence, nitrogen metabolism, and protein and carbohydrate contents of Indian mustard (Brassica juncea L.) seedlings in the absence and presence of arsenic (Na2HAsO4.7H2O: As1; 15 mg As kg-1 sand and As2; 30 mg As kg-1 sand) stress was analyzed. Arsenic with its rising concentration negatively affected the fresh weight, root/shoot ratio, leaf area, photosynthetic pigments content, photosynthetic oxygen yield, and chlorophyll a fluorescence parameters: the O-J, J-I and I-P rise, QA- kinetic parameters, i.e., ΦP0, Ψ0, ΦE0, and PIABS, along with Fv/F0 and Area while increased the energy flux parameters, i.e., ABS/RC, TR0/RC, ET0/RC, and DI0/RC along with F0/Fv and Sm due to higher As/S and As/Ca ratio in test seedlings; however, exogenous application of S and Ca and their combined effect notably counteracted on As induced toxicity on growth and other important growth regulating processes. Moreover, inorganic nitrogen contents, i.e., nitrate (NO3-) and nitrite (NO2-) and the activities of nitrate assimilating enzymes, viz., nitrate reductase (NR) and nitrite reductase (NiR) and ammonia assimilating enzymes, viz., glutamine synthetase (GS) and glutamate synthase (GOGAT) along with protein and carbohydrate contents were severely affected with As toxicity; while under similar condition, ammonium (NH4+) content and glutamate dehydrogenase (GDH) activity in both root and leaves showed reverse trend. Furthermore, S and Ca supplementation alone and also in combination to As stressed seedlings ameliorated these parameters except NH4+ content and GDH activity, which showed an obvious reduction under similar conditions. These findings point out that exogenous application of S and/or Ca particularly S+Ca more favorably regulated the photosynthesis, contents of protein, carbohydrate and inorganic nitrogen, and the activities of nitrate and ammonia assimilating enzymes, which might be linked with the mitigation of As stress. Our results suggest that exogenous application of S+Ca more efficiently defends Brassica seedlings by declining As accumulation in root and shoot tissues and by maintaining the photosynthesis and nitrogen metabolism as well.

Abstract  There is interconnection between soil quality, water quality, and food safety that is necessary to evaluate pollution levels in these components. Soil contamination by potentially hazardous elements may pose direct and indirect threats as negative impacts on the plant growth and yield, entering the human food chain with potentially negative effects on human health. Intensive agriculture (industrial agriculture) in agro-industry could have resulted in an enrichment of potentially hazardous elements in soils and accumulation in crops because of excess use of fertilizers and amendments. Unfortunately, despite these conditions, there were few or no investigations of potentially hazardous elements in farming areas of agro-industry sectors. This research was undertaken in agricultural lands of Moghan agro-industry complex located in the Moghan's plain (as one of the main poles of agriculture) in the north of Ardebil province and west of the Caspian Sea. The present study was designed to investigate the concentrations of Cd and Pb in agricultural soils, irrigation water, Alfalfa and commonly used fertilizers in the agricultural lands of Moghan agro-industry. The results showed that the average concentrations of the Cd and Pb in agricultural soils of Moghan agro-industry complex were 0.55 and 163.60 mg.kg(-1), respectively. Moreover, the mean concentrations of Cd and Pb were 0.61, and 0.07 mu g.l(-1) in irrigation water samples, respectively, 0.45, and 0.009 mg.kg(-1) in Alfalfa samples, 0.62 and 51.87 mg.kg(-1) in superphosphate fertilizer samples, 0.67 and 51.87 mg.kg(-1) in animal manure samples and 0.001 and 3.66 mg.kg(-1) in urea fertilizer samples. Superphosphate fertilizer showed higher content of Cd and Pb than urea fertilizer, indicating the importance of phosphate fertilizer on the accumulation of potentially hazardous elements in soils. Based on the results of this research and values of Transfer Factor (TF), it was found that the Alfalfa (Medicago scutellata) had high ability to accumulate cadmium from contaminated soils, but the accumulation rate of Pb was much lower than Cd. Phosphate fertilizer and/or animal manure may be the main sources of contribution by Cd and Pb in the agricultural soils of the study area, but irrigation water had no significant effect on the potentially hazardous elements accumulation in soil.