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[Display omitted] • Biotransformation of Fe2+, Mn2+, NH 4 + shows different spatial distribution pattern. • Competitive interplay dominates the co-oxidation processes of the contaminants. • The influence of microorganism is manifested by the change of transformation rates. A dynamic column experiment using aquifer medium collected from a riverbank filtration (RBF) site in Northeast China was conducted to investigate the biogeochemical transformation processes of iron (Fe2+), manganese (Mn2+), ammonium (NH 4 +) and their interaction under coexisting conditions in real groundwater. Water parameters such as contaminant concentrations, pH and dissolved oxygen (DO) were determined while microbial analysis for the aquifer medium was performed through 16S rRNA sequencing. The results revealed that biochemical oxidation, reductive dissolution, adsorption were among the critical biogeochemical processes involved in the transformation of Fe2+, Mn2+ and NH 4 +, in which biological processes were the core process. The transformation rate of Fe2+, Mn2+ and NH 4 + jointly revealed that the competition for DO existed throughout their co-oxidation process, and determined the spatial characteristics of their transformation processes to a certain extent. Fe2+ oxidation and nitrification primarily occurred in the upper oxidation zone (100 cm–70 cm), Mn2+ transformation and anaerobic ammonium oxidation (ANAMMOX) occurred mainly beneath the oxidation zone. The predominant area of microbial growth and metabolism was another key factor related to the spatial characteristics of biotransformation. The microbial analysis illustrated that Pseudomonas , Arthrobacter , Gallionella , Acinetobacter , Bacillus were among the dominant genera related to iron-oxidizing bacteria (IOB) and manganese-oxidizing bacteria (MnOB). The IOB-related genera were distributed mainly at 80 cm–60 cm with a relative abundance of 49%, MnOB-related genera were the most abundant (35%) bacteria at 60 cm–40 cm, and nitrifying bacteria (Nitrospira and Nitrosomonas) mainly existed in the upper part of the 100 cm–70 cm where nitrification occurred. The influence of microbial activity by changing chemical environment was manifested through the variation of transformation intensity during the experiment. The iron and manganese oxides generated by the bio-oxidation of Fe2+ and Mn2+ contributed significantly to the transformation of all three contaminants. The results may be valuable for understanding the evolution mechanism of groundwater when contaminated simultaneously with Fe2+, Mn2+ and NH 4 +. [ABSTRACT FROM AUTHOR]

Here, a new integrated methodology framework has been proposed for source apportionment and source-oriented risk evaluation, and applied to identify the characteristics, sources and health risks of PAHs in the soils of a typical cold region in Northeastern China. To this end, a large-scale data set containing 1780 soil samples and 16 priority PAHs has been collected from the study area. Two advanced receptor models, positive matrix factorization (PMF) and multivariate curve resolution-weighted alternating least-squares (MCR-WALS), have been comparatively employed to apportion the pollution sources of soil PAHs, with the help of a set of modified literature PAH source fingerprints. Further, the apportionment results have been incorporated into a probabilistic incremental lifetime cancer risk model for assessing the source-specific health risk of soil PAHs. Notably, the PMF and MCR-WALS models have apportioned essentially same results. The coal combustion and gasoline engine are identified as the main contributors of soil PAHs, with contributions of 57.9–58.1% and 25.2–22.2%, respectively. The health risks posed by PAHs in the soils are negligible for both adult and children; relatively, source-oriented risk assessment shows coal combustions make the largest contribution to the total risk of PAHs (56.1%), followed by gasoline engine (22.5%) and coke oven (21.4%). [Display omitted] • A new integrated framework has been proposed for characterizing sources and risks of PAHs. • Apportionment results have been used for assessing source-specific health risk of PAHs. • The MCR-WALS model has apportioned essentially same results with PMF. • Coal combustion, gasoline engine and coke oven are the main pollution sources of PAHs. • Coal combustion has made the largest contribution to the total risk of PAHs (56.1%). [ABSTRACT FROM AUTHOR]

Heavy metal pollution has been a global concern and key points of environmental pollution prevention and control due to the growing problems of urbanization and industrialization. Rapidly and correctly apportioning sources of heavy metal is still a great challenge because of the stability of source fingerprint and complex interaction of multiple contaminants and sources. In this study, we perform a combination of optimization of pollution source fingerprint and source apportionment through jointly utilizing two machine classification and screening methods for characterizing the pollution sources of heavy metal in the sediments of an urban river and its surrounding soils. Dominance-based rough set model (DRS), content optimization tools, and multivariate curve resolution-alternating least squares model (MCR-WALS) were employed to screen representative pollution source samples, optimize pollution source fingerprint, and apportion the potential sources of heavy metals, respectively. Further, Support vector machine (SVM) was adopted to correspondence analysis results and pollution fingerprint based on the factor characteristics for achieving source apportionment accurately. Results showed that the pollution source pollution source fingerprints optimized by DRS and optimization tools are more representative and stable, and the results obtained by SVM and MCR-WALS are more accurate comparing with traditional methods. As whole, source apportionment suggested that printing and dyeing, chemical, electroplating, metal processing were the main origins of heavy metals in this area and the proportions of them in sediment and soil pollution sources were 67.05% and 28.43%, respectively. Besides, coal combustion was also the main sources of heavy metal pollution in soils, accounting about 34.16%. Results of the study can advance our knowledge to better understand the characterization of heavy metal pollution in the peri-urban ecosystem and to design effective targeted strategies for reducing heavy metal pollution diffusion. [Display omitted] • A combination of fingerprint screening and source apportionment was performed. • Characteristics and source-sink relationship of heavy metals in the river-soil system was studied. • Source apportionment was executed using MLR-WALS combined with SVM. • Multiple complex industrial activities were the dominant same type contributor of heavy metals in the river sediments. [ABSTRACT FROM AUTHOR]

This study aims to better understand the effects of heavy metal enrichment on microbiomes and resistomes and the source-specific ecological risks of metals in the sediments of an urban river. Geo-accumulation index and enrichment factor suggested the river sediments were contaminated by Cd, Cu, Pb, and Zn in varying degrees. High-throughput sequencing-based metagenomics analysis identified 430 types of antibiotic resistance genes (ARGs), dominated by the multidrug, MLS, bacitracin, quinolone, and aminoglycoside ARGs, and 52 metal resistance genes (MRGs) mainly conferring resistance to zinc, copper, cadmium, lead, mercury and multiple metals. Spearman correlation analysis and Mantel test showed the heavy metal enrichment exerted significant effects on the microbial community, ARGs and MRGs. Source apportionment using positive matrix factorization revealed that natural source (42.8%) was the largest contributor of metals in the river sediments, followed by urban activities (35.4%) and a mixed source (21.7%). However, when incorporating the apportionment results into a modified risk model to evaluate the source-specific ecological risks, results showed human activities dominated the risks of metals. Comparatively, the urban activities majorly caused moderate- and considerable- ecological risks, while the mixed source with respect to agricultural and industrial activities contributed higher percentages on high- and extremely high- ecological risks. ga1 • Effects of heavy metal enrichment on microbiomes and resistomes were studied. • A modified ecological risk index was constructed to evaluate the source-specific risks. • Heavy metal enrichment exerted effects on the microbial community, ARGs and MRGs. • Human activities dominated the ecological risks of heavy metals in the river sediments. [ABSTRACT FROM AUTHOR]

Vadose zone is an important channel for sulfonamide contamination into groundwater, and the processes of adsorption and migration in the vadose zone are complicated. In this study, we focused on three sulfonamide antibiotics (sulfamethoxazole, sulfamethazine and sulfamethoxypyridazine) in the groundwater of Limin drinking water resource in northeastern China and assessed their migration potential in aquifers. Analysis was based on adsorption batch tests, a column experiment. Some key influencing factors including pH, iron, manganese and ammonia were considered. The results showed that the concentration of sulfamethoxypyridazine in groundwater is higher, ranging between 7 and 30 ng/L, the concentrations of sulfamethoxazole and sulfamethazine are relatively lower and no more than 1 ng/L. The adsorption capacity of the three antibiotics on vadose zone materials shows the following order: sulfamethoxypyridazine > sulfamethazine > sulfamethoxazole. Furthermore, for the three sulfonamides, the adsorption is higher in the medium of 0–20 cm (finer particle size, higher clay content and lower sand content) than that in 80–100 cm. Coexisting ions (iron, manganese and ammonia) promote the adsorption of sulfonamides, and the adsorption of sulfonamides decreases as the water pH increases. The column experiment also shows that the three sulfonamides have strong migration abilities and pose a considerable risk to groundwater. • Sulfonamides contamination in a drinking water resource observed. • Adsorption batch tests and a column experiment conducted. • Factors influencing on sulfonamides transport analyzed. • Sulfonamides showed migration ability to groundwater with the order: SMX > SM2 > SMP. [ABSTRACT FROM AUTHOR]

Surface-water irrigation is one of the most important irrigation methods in areas with abundant surface water. Although this method of irrigation is both economical and convenient, many contaminants are also introduced into the soil-water systems such as organophosphorus pesticides (OPPs). To study the influence of surface-water irrigation on the distribution of OPPs in soil-water systems, 42 water samples (38 groundwater and four surface water) and 85 soil samples (78 profile soil samples and seven topsoil samples) were taken from Shahu in the Jianghan Plain, China. Shahu is a typical Chinese surface-water irrigation district. During sampling, three types of areas were considered: surface-water irrigated areas, groundwater-irrigated areas away from rivers, and non-irrigated areas adjacent to rivers. The results showed that the concentrations of OPPs in the groundwater and soil in the surface-water irrigated farmland were higher than those in groundwater-irrigated farmland. The groundwater flow field and surface-water irrigation were responsible for the OPPs. Thus, it is clear that the surface-water irrigation had a strong influence on the distribution of OPPs in soil-water systems. Principal component analysis for OPPs content in groundwater showed that the key influencing factors on the distribution of OPPs in groundwater were the groundwater flow field and current pesticide use. Image 1 • Methamidophos, Diazinon and Omethoate were the main OPPs in the soil-water system. • OPPs in the topsoil and subsoil had adverse effects to the safety of agricultural products. • OPPs in the subsoil and groundwater had significant spatial distribution characteristics. • Surface-water irrigation influenced the distribution of OPPs in the study area. • Groundwater flow field and current pesticide use were two major influencing factors. [ABSTRACT FROM AUTHOR]

Nanofibers are solid fibers with diameters ranging from a few to hundreds of nanometers and lengths up to several meters. Nanofibers can offer many attractive properties, such as high specific surface area and large aspect ratio, and satisfy some special needs of analytical chemistry using different functionalization and modification methods. Nanofibers have been applied in different analytical techniques and processes, including optical analysis (colorimetery, fluorescence, chemiluminescence, surface-enhanced Raman scattering), ultra-thin layer chromatography, mass spectrometry ionization techniques, electrochemical analysis, sample preparation techniques, gas sensors and biological sensors. The trends and advances of application techniques based on nanofibers and the corresponding synthesis or derivatization methods were summarized and compared according to the survey of more than 1100 articles in recent two decades. The challenges and prospects of nanofiber-based applications in analytical chemistry were also addressed finally. • NFs offer many attractive properties for application in analytical chemistry. • NF-based MS ionization, sensor, optical and electrochemical analysis were reviewed. • NF-based UTLC and sample preparation techniques were summarized. • The corresponding NF synthesis and derivatization methods were classified. • The challenges and prospects of NF-based analytical chemistry were also addressed. [ABSTRACT FROM AUTHOR]

• CDs/Fe 3 O 4 @CS pomegranate-like composites were successfully synthesized. • The CDs/Fe 3 O 4 @CS formation processes and mechanism were proposed. • CDs/Fe 3 O 4 @CS exhibits high catalytic activities for three peroxides. • CDs/Fe 3 O 4 @CS has low activation energy and good reusability. • The roles of reactive species in degradation pathways were discussed. Carbon dots and nanomagnetites encapsulated in amorphous carbon spheres (CDs/Fe 3 O 4 @CS) with a pomegranate-like structure were synthesized via a solvothermal method and their peroxide activation performances for ibuprofen degradation were investigated in this work. The pomegranate-like nanocomposites, with an average diameter of 451.9 nm, possessed multicores and a 20–50 nm thick amorphous carbon shell. The multicores were composed of multiple 3.9–9.8 nm carbon dots and 5.6–18.6 nm nanomagnetites, as confirmed by X-ray diffraction, X-ray photoelectron, Raman and photoluminescence spectra. The Fe 3 O 4 loading was calculated to be 50.9 wt% according to thermo-gravimetric analysis. CDs/Fe 3 O 4 @CS had a specific surface area of 101.5 m2/g and the saturation magnetization of 26.8 emu/g. The CDs/Fe 3 O 4 @CS formation mechanism was proposed based on the characterization results. CDs/Fe 3 O 4 @CS exhibited high catalytic activities for peroxymonosulfate, persulfate and H 2 O 2 with and without visible light illumination, and persulfate showed higher ibuprofen degradation efficiencies. The amorphous carbon shell might benefit ibuprofen enrichment, the nano Fe 3 O 4 provided sufficient reactive sites to activate persulfate, and the CDs could accelerate the degradation due to their excellent electron donating and accepting abilities. The ibuprofen degradation in the CDs/Fe 3 O 4 @CS activated persulfate system followed a pseudo-first-order kinetic model and the activation energy was derived as 27.2 kJ/mol. The CDs/Fe 3 O 4 @CS also presented good reusability performances in the repeated experiments with visible light illumination. Singlet oxygen, hydroxyl and sulfate radicals were verified and the roles of these reactive species in ibuprofen degradation pathways were discussed based on intermediate analysis. The pomegranate-like nanocomposites might provide a potential promising catalyst for pollution control technologies. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance is a growing public health concern, and environment is regarded as an important reservoir and dissemination route for antibiotic resistance genes (ARGs). To prevent and control ARG pollution, it is essential to correctly disentangle source-sink relationship of ARGs in the environment. However, accurately apportioning sources of ARGs is still a big challenge due to the complex interaction of multiple sources and contaminants in the environment with changing dynamics. In this study, we addressed this problem and focused on identifying the potential sources of ARGs in a peri-urban river by jointly utilizing two novel microbial source tracking methods. To attain the objective, sediment/water samples were collected from the peri-urban river and four ARG-associated ecotypes including effluents of sewage treatment plants (STPs), STP influent, chicken manures and pig manures. The high-throughput profilings of ARGs and microbial taxa in the river sediments and the four ecotypes were comprehensively characterized in combination of shotgun sequencing and metagenomic assembly analysis. CrAssphage , a recently-discovered DNA bacteriophage, was employed to track the impact of human fecal pollution on ARGs in the river sediments. Further, SourceTracker, a machine-learning classification tool, was used for quantifying the contributions of potential sources to ARGs in the river sediments based on the metagenomic signatures of ARGs and microbial taxa. In total, 888 ARG subtypes belonging to 29 ARG types were detected across all samples, including mcr-1 and a range of carbapenemases types. Statistical analyses suggested different ecotypes generally had distinct profiles of both ARGs and microbial taxa, while the ARG compositions were significantly correlated with the microbial community. Source tracking with crAssphage showed the presence of ARGs in the river sediments might be largely impacted by the extent of human fecal pollution, which was also confirmed by the analyses of SourceTracker that the discharge from STPs was the largest contributor of ARGs (81.6–92.1%) and microbes (49.3–68.1%) in the river sediments. Results of the study can help us to better understand the characterization of ARGs in the peri-urban ecosystem and to design effective prevention and control strategies for reducing ARG dissemination. • 888 ARG subtypes belonging to 29 ARG types were detected in the study. • CrAssphage was a good marker for tracking human fecal pollution in the study area. • Effluent of STPs was the largest contributor of ARGs in the river sediments. [ABSTRACT FROM AUTHOR]

Microbial community, as the decomposers of constructed wetland (CW), plays crucial role in biodegradation and biotransformation of pollutants, nutrient cycling and the maintenance of ecosystem balance. In this study, 9 water samples, 6 sediment samples, and 8 plant samples were collected in Annan CW, which has the functions of water treatment and wetland culture park. The characteristics of microbial community structure in different media were illustrated by using of high-throughput sequencing-based metagenomics approach and statistical analysis. Meanwhile, this study identified and classified human pathogens in CW to avoid potential risks to human health. The results showed that dominant bacteria phyla in CW include Proteobacteria, Bacteroides, Actinobacteria, Firmicutes and Verrucomicrobia. The distribution of microorganisms in three media is different, but not significant. And the pH and DO profoundly affected microbe abundance, followed by water temperature. The microbial diversity in sediments is the highest, which is similar with the detection of human pathogens in sediments. Moreover, compared with Calamus, Lythrum salicaria and Reed, Scirpus tabernaemontani has fewer pathogenic microorganisms. The distribution of microorganisms in the CW is complex, and a variety of human pathogens are detected, which is more prone to create potential risks to human health and should receive additional attention., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

With the ongoing development and utilization of nuclear energy, uranium pollution has become an increasingly serious issue. Although many adsorbents are able to remove hexavalent uranium (U(VI)) from aqueous solution, the development of a high capacity adsorbent exhibiting superior stability would be beneficial. Grafting poly(amidoxime) (PAO) onto reduced graphene oxide (rGO) provides suitable U(VI) adsorption performance but the PAO is prone to agglomeration. The present work used density functional theory calculations to predict that PAO would bond with pyrrolic N atoms in nitrogen-doped rGO (N-rGO). To confirm this, PAO-grafted rGO (PAO-rGO) and PAO-grafted N-rGO (PAO-N-rGO) were prepared and characterized and the successful grafting of PAO on N-rGO was demonstrated. Adsorption experiments demonstrated that PAO-N-rGO exhibit superb U(VI) adsorption performance compared with the original PAO-rGO under acidic conditions. As for competing metal ions, Cu 2+ , Al 3+ , and Ca 2+ have a greater impact on U(VI) adsorption than Na + , Mg 2+ , and K + both for PAO-rGO and PAO-N-rGO. The maximum adsorption capacities of PAO-rGO and PAO-N-rGO for U(VI) were calculated to be 1500.26 and 1545.95 mg g -1 , respectively. The mechanism of nitrogen doping promoting uranium(VI) adsorption can be attributed to enhanced PAO grafting and improvement of adsorption performance of the rGO. This work demonstrates that nitrogen doping is a viable strategy for enhancing the U(VI) adsorption performance of PAO-rGO.

Peat-derived organic matter, as powerful chelators, is of great significance for the transport of Fe to the ocean and the enhancement of dissolved Fe. However, the iron binding capacity of molecular weight (MW)-fractionated dissolved organic matter is variable, due to its structure and composition heterogeneity. In this work, we used the standard Pahokee Peat fulvic acid (PPFA) as an example, and investigated the spectroscopy properties and Fe(III) binding ability of PPFA and different molecular weight fractions by UV−Vis absorbance and fluorescence spectroscopy and the Donnan Membrane Technique (DMT). The results showed binding sites for Fe(III) at the 263 nm and >320 nm regions in differential absorbance spectra. Upon increasing the iron concentration to 18.00 μmol·L−1, the critical binding capacity was exceeded, which resulted in a decrease in absorbance. Fe(III) was found to prefer to bind to humic-like components, and ultraviolet humic-like fluorophores displayed stronger binding strength. High molecular weight PPFA fractions (>10 kDa) possessed more aromatic and hydrophobic components, displayed a higher degree of humification, and exhibited higher metal binding potential. Furthermore, the speciation analysis and stability constant (cK) were calculated using Donnan membrane equilibrium. The correlation between cK values and PPFA spectral properties demonstrated that aromaticity, hydrophobicity, molecular weight and humification degree were crucial indices of PPFA−Fe(III) affinity. Significantly, the humification degree, represented by HIX, showed the strongest correlation (r = 0.929, p = 0.003), which could be used to estimate the binding strength. This study provides further understanding of the complexation mechanism of iron and DOM in the peat environment and identifies the considerable effect of molecular weight.

Heavy metals pollution in groundwater and the resulting health risks have always been an environmental research hotspot. However, the available information regarding this topic and associated methods is still limited. This study collected 98 groundwater samples from a typical agricultural area of Songnen Plain in different seasons. The pollution status and sources of ten heavy metals (As, Ba, Cd, Co, Cr (VI), Cu, Fe, Mn, Ni, Pb, and Zn) were then analyzed and compared. In addition, the human health risks assessment (HHRA) model was used to calculate human health risks caused by heavy metals in groundwater. The results revealed that heavy metals were mainly distributed in the northwest of the study area and along the upper reaches of the Lalin river and that the concentrations of heavy metals were higher during the wet season than the dry season. Industrial and agricultural activities and natural leaching are the main sources, and each kind of heavy metal may have different sources. Fe and Mn are the primary pollutants, mainly caused by the native environment and agricultural activities. The exceeding standard rates are 71.74% and 61.54%, respectively based on the Class III of Quality Standard for Groundwater of China (GB/T 14848-2017). The maximum exceeding multiple are 91.45 and 32.05, respectively. The health risks of heavy metals borne by different groups of people were as follows: child > elder > young > adult. Carcinogenic heavy metals contribute to the main risks, and the largest risks sources are Cr and As. Therefore, the government should appropriately restrict the use of pesticides and fertilizers, strictly manage the discharge of enterprises, and control man-made heavy metals from the source. In addition, centralized water supply and treatment facilities shall be established to prevent the harm of native heavy metals.

Recently, crAssphage has been proposed as a human-specific marker for tracking fecal contamination. However, its performance has always been validated in a limited number of host samples, which may obscure our understanding of its utility. Furthermore, few studies have quantified confidence of fecal contamination when using crAssphage . Here, we evaluate the performance and confidence of crAssphage by analyzing a large panel of metagenomic data sets combined with Bayesian analyses. Results demonstrate that crAssphage exhibits superior performance with high host sensitivity and specificity, indicating its suitability for tracking human fecal sources. With the marker, a high confidence (>90%) can be obtained and particularly, multiple samples with positive results provide a near certainty of confidence. The application of crAssphage in the sediments of three Chinese urban rivers shows a high confidence of >97% of human fecal contamination, suggesting the serious challenge of sewage pollution in these environments. Additionally, significant correlation is observed between crAssphage and antibiotic resistance genes (ARGs), expanding the utilization of crAssphage for pollution management of ARGs. This study highlights the benefit of using metagenomic-based analysis for evaluating the performance and confidence of microbial source tracking markers in the coming era of big data with increasing resources in available metagenomic data.

Based on the chemiluminescence (CL) phenomenon of peroxymonosulfate (PMS) and Tb(III) enhanced by its ligand in a micelle microenvironment, a fast and sensitive flow injection CL method for PMS detection was proposed and applied to the analysis of different samples and PMS decomposition. Under the optimized conditions, a linear range was obtained from 4.0 × 10 -6  mol L -1 to 2.0 × 10 -4  mol L -1 with a high correlation coefficient (r = 0.9997), detection limit of 5.0 × 10 -7  mol L -1 (S/N = 3) and relative standard deviation of 2.4% for 1.0 × 10 -5  mol L -1 PMS (n = 9). This was successfully applied to the determination of PMS in Virkon powder, tap water, and swimming pool water samples with satisfactory recoveries from 94.8% to 104.8%. In particular, the analytical frequency could be as fast as five samples per minute because there was no reaction step before analysis and the CL phenomenon was instantaneous. Therefore, this CL method has also been successfully applied to investigate the PMS decomposition profiles in carbon material (carbon nanotubes, carbon nanofibres, activated carbon and graphene oxide) catalysis systems, which followed pseudo-first-order kinetics with good correlation coefficients (r > 0.9305). Quenching experiments and electron spin resonance spectra verified that the CL phenomenon was due to the formation of singlet oxygen, and that hydroxyl and sulfate radicals might be important in the generation of singlet oxygen. Tb(III) is the luminescent emitter according to the characteristics emission bands of the fluorescence and CL spectra in different media., (© 2019 John Wiley & Sons, Ltd.)

We explored the effect of the presence or absence of humic acid (HA) on the sorption behaviour of Sr onto soil. We examined three different experimental cases for Sr sorption: (1) sorption in the presence of only colloidal HA, (2) sorption in the presence of only soil and (3) sorption in the presence of both colloidal HA and soil (HS). A batch technique was used to study the influencing factors, including the amount of colloidal HA, solid content, pH, initial concentration of Sr and contact time. The experiments showed that the influencing factors significantly affected the sorption process. For example, in the case of soil and HS, the sorption percentage increased rapidly with increasing solid content at m/V < 20 g/L, changing from 8.35% and 37.54% to 49.09% and 77.03%, respectively. Moreover, scanning electron microscopy and Fourier transform infrared spectroscopy were used to characterize samples. The kinetics and isotherms of Sr were best described by the pseudo-second-order and Langmuir models, which indicated that the process was controlled by chemisorption and uniform monolayer sorption with constant energy on the outer surface. These findings provide valuable information for predicting strontium migration in radioactive waste disposal sites.

The issue of contaminated sites has been highlighted as an immediate priority in the 13th Five-Year Plan of China. Identification and prioritization of contaminated sites are of key importance for proposing effective strategies for the regional management of contaminated sites. In this study, three advanced multi-attribute methodologies, the risk-based priority methodology, the regional risk assessment methodology, and the dominance-based rough set approach (DRSA), were comparatively employed to screen contaminated sites in, Guangxi, Southwest of China. The results of the three prioritizations show that the highest ranking site identified by the three methods had great agreement. In regard to the screening attributers, while the risk-based prioritization methodology and regional risk assessment methodology allowed a high discrimination in the screening of contaminated sites associated with different attributes, such as farmland, residential areas, contaminant level, number of people, area, storage quality, site service life, and surrounding communities, the DRSA allowed the identification of contamination strength (CS) and contamination potential (CP).

In this study, the commercially available secnidazole was successfully converted to secnidazole xanthate (SNXT), in which the xanthate group can act as a bifunctional chelator to coordinate with 99m Tc. 99m Tc-nitrido complex of SNXT( 99m TcN-SNXT) and 99m Tc-oxo complex of SNXT( 99m TcO-SNXT) were prepared with high radiochemical purity. Both of the complexes were found to be stable in vitro and to exhibit similar hydrophilicity. In addition, comparative in vitro cell uptake studies under anoxic and normoxic conditions demonstrated that both agents were preferentially taken up by hypoxic cells. Biodistribution studies in mice bearing S180 tumor showed 99m TcO-SNXT exhibited a higher tumor uptake and tumor-to-muscle ratio than 99m TcN-SNXT. Furthermore, in SPECT imaging study, 99m TcO-SNXT exhibited a clear accumulation in tumor at 2 h post-injection, suggesting its potential to be a novel hypoxia imaging agent., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The distribution of 15 phthalate acid esters (PAEs) in water, sediment and suspended particle samples from representative lakes of Beijing was investigated and its relationship with anthropogenic activities was also assessed. The sample preparation and analysis methods for PAEs, using solid-phase extraction or microwave assisted extraction coupled with gas chromatography-mass spectrometry, were developed to achieve the satisfactory detection limits and recoveries. The analysis results indicated occurrences of most target PAEs were widespread in the researched lakes with the total PAE concentrations ranged from 0.386 to 3.184 μg/L in water, from 52.6 to 8216.4 ng/g dry weight in sediments and from 138.7 to 2052.4 μg/g dry weight in suspended particles. Di-(2-ethylhexyl) phthalate and di-butyl phthalate were the predominant PAEs, frequently being detected in all matrices, followed by di-iso-butyl phthalate and butyl benzyl phthalate. It was also found that anthropogenic activities were associated with the spatial distribution of phthalates in sediments considering its relationship with population distribution characteristics of Beijing., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Characterizing water quality and identifying potential pollution sources could greatly improve our knowledge about human impacts on the river ecosystem. In this study, fuzzy comprehensive assessment (FCA), pollution index (PI), principal component analysis (PCA), and absolute principal component score-multiple linear regression (APCS-MLR) were combined to obtain a deeper understanding of temporal-spatial characterization and sources of water pollution with a case study of the Jinjiang River, China. Measurement data were obtained with 17 water quality variables from 20 sampling sites in the December 2010 (withered water period) and June 2011 (high flow period). FCA and PI were used to comprehensively estimate the water quality variables and compare temporal-spatial variations, respectively. Rotated PCA and receptor model (APCS-MLR) revealed potential pollution sources and their corresponding contributions. Application results showed that comprehensive application of various multivariate methods were effective for water quality assessment and management. In the withered water period, most sampling sites were assessed as low or moderate pollution with characteristics pollutants of permanganate index and total nitrogen (TN), whereas 90% sites were classified as high pollution in the high flow period with higher TN and total phosphorus. Agricultural non-point sources, industrial wastewater discharge, and domestic sewage were identified as major pollution sources. Apportionment results revealed that most variables were complicatedly influenced by industrial wastewater discharge and agricultural activities in withered water period and primarily dominated by agricultural runoff in high flow period.

In order to investigate the distribution of the total petroleum hydrocarbons (TPH) in groundwater and soil, a total of 71 groundwater samples (26 unconfined groundwater samples, 37 confined groundwater samples, and 8 deeper confined groundwater samples) and 80 soil samples were collected in the Songyuan oilfield, Northeast China, and the vertical variation and spatial variability of TPH in groundwater and soil were assessed. For the groundwater from the unconfined aquifer, petroleum hydrocarbons were not detected in three samples, and for the other 23 samples, concentrations were in the range 0.01-1.74 mg/l. In the groundwater from the confined aquifer, petroleum hydrocarbons were not detected in two samples, and in the other 35 samples, the concentrations were 0.04-0.82 mg/l. The TPH concentration in unconfined aquifer may be influenced by polluted surface water and polluted soil; for confined aquifer, the injection wells leakage and left open hole wells may be mainly responsible for the pollution. For soils, the concentrations of TPH varied with sampling depth and were 0-15 cm (average concentration, 0.63 mg/g), >40-55 cm (average concentration, 0.36 mg/g), >100-115 cm (average concentration, 0.29 mg/g), and >500-515 cm (average concentration, 0.26 mg/g). The results showed that oil spillage and losses were possibly the main sources of TPH in soil. The consequences concluded here suggested that counter measures such as remediation and long-term monitoring should be commenced in the near future, and effective measures should be taken to assure that the oilfields area would not be a threat to human health.

Precipitation water samples were collected at an urban site in Beijing in a hydrological cycle (July 2008-July 2009), and analyzed for TDS, total alkalinity, total hardness, free CO₂, soluble SiO₂, bromide, sulfide, phosphate, major ions (K(+), Na(+), Ca(2+), Mg(2+), NH₄(+), HCO₃(-), Cl(-), SO₄(2-), NO₃(-)), trace elements (CO₃(2-), Mn, Sr(2+), Fe(2+), Fe(3+), Al, F(-), NO₂(-)), stable isotopes ((2)H and (18)O), and radioactive isotope ((3)H). In addition, available published hydrochemical and isotopic data of precipitation of Beijing in the past were also collected and conjointly analyzed. Most of the parameters of samples tested varied considerably in the hydrological cycle. In general, HCO₃(-) and SO₄(2-), and Ca(2+) and NH₄(+) are the dominant anions and cations, respectively. Using Na(+) as an indicator of marine origin, and Al for the terrestrial inputs, the proportions of major elements from sea salt and terrestrial sources were estimated by using the combination of statistical analysis methods and analogy method. More than 70.1% of Cl(-), 98.1% of Ca(2+), and 93.6% of K(+) were non-sea-salt origin, while more than 98.4% of Na(+) was from marine sources. The LMWL (Local Meteoric Water Line) was obtained with an equation of δ(2)H=7.0181δ(18)O+3.5231 (‰, R(2)=0.86, n=36), which was similar to GMWL (Global Meteoric Water Line). δ(2)H, δ(18)O and Δ-excess changed radically with month and season, but had no apparent seasonal effect, precipitation amount effect, and temperature effect. The annual mean values of Δ-excess for 1979 (16.5‰) and 1980 (16.3‰) were much bigger than that for 2007 (7.2‰), 2008 (2.1‰) and 2009 (4.5‰). The composition of (2)H and (18)O was probably intrinsically determined by the sources of water vapor and the physical and chemical processes occurred along the migration paths of water vapor from sources to the aimed precipitation area. Temporal change of (3)H was only influenced by the nuclear testing in the early 1960s worldwide and the natural yield of (3)H in the upper atmosphere intrinsically. (3)H had nearly approached to the natural levels, which would bring difficulty if not invalidation to groundwater dating using (3)H technique., (Copyright © 2013 Elsevier B.V. All rights reserved.)

In this study, a method of positive matrix factorization (PMF) combined support vector machines (SVMs) was adopted to identify possible sources and apportion contributions for trace element pollution in surface sediments from the Jinjiang River, Southeastern China. Utilizing diagnostics tools, four significant factors were extracted from sediment samplers, which were collected in December 2010 at 15 different sites. By treating source identification as a pattern recognition problem, the factor loadings derived from PMF were classified by SVM classifiers which have been trained and validated with fingerprints of eight potential source categories. Using SVM, industrial wastewater from lead ore mining and metal handcraft manufacture, atmospheric deposition, and natural background were identified as main sources of trace element pollution in surface sediments from the Jinjiang River, which were affirmed by visually comparing compound patterns and the differences between the predicted and actual fractional compositions. Apportionment results showed that source of lead ore mining made the largest contribution (33.62 %), followed by atmospheric deposition (30.99 %), metal handcraft manufacture (30.09 %), and natural background (5.29 %).

The nonpoint source (NPS) pollution is difficult to manage and control due to its complicated generation and formation. Load estimation and source apportionment are an important and necessary process for efficient NPS control. Here, an integrated application of semi-distributed land use-based runoff process (SLURP) model, export coefficients model (ECM), and revise universal soil loss equation (RUSLE) for the load estimation and source apportionment of nitrogen and phosphorus was proposed. The Jinjiang River (China) was chosen for the evaluation of the method proposed here. The chosen watershed was divided into 27 subbasins. After which, the SLURP model was used to calculate land use runoff and to estimate loads of dissolved nitrogen and phosphorus, and ECM was applied to estimate dissolved loads from livestock and rural domestic sewage. Next, the RUSLE was employed for load estimation of adsorbed nitrogen and phosphorus. The results showed that the 12,029.06 t a(-1) pollution loads of total NPS nitrogen (TN) mainly originated from dissolved nitrogen (96.24 %). The major sources of TN were land use runoff, which accounted for 45.97 % of the total, followed by livestock (32.43 %) and rural domestic sewage (17.83 %). For total NPS phosphorous (TP), its pollution loads were 570.82 t a(-1) and made up of dissolved and adsorbed phosphorous with 66.29 and 33.71 % respectively. Soil erosion, land use runoff, rural domestic sewage, and livestock were the main sources of phosphorus with contribution ratios of 33.71, 45.73, 14.32, and 6.24 % respectively. Therefore, land use runoff, livestock, and soil erosion were identified as the main pollution sources to influence loads of NPS nitrogen and phosphorus in the Jinjiang River and should be controlled first. The method developed here provided a helpful guideline for conducting NPS pollution management in similar watershed.

The assessment of groundwater vulnerability to pollution has become a useful tool for groundwater pollution prevention and control. Following the theory of overlay index method and with the aid of GIS technique and a statistical method, this study employed a modified DRASTIC model to assess the groundwater vulnerability to nitrate in Jilin City of northeast China. In order to reduce the subjectivity of the overlay index method, the model was optimized by rebuilding the index system, adjusting the rating scale of each index, reassigning the index weights and comparing grading methods for groundwater vulnerability to nitrate. The criteria for these optimizations were the correlation coefficient of each index with the nitrate concentration in groundwater. Net recharge (R), soil type (S), impact of vadose zone (I), groundwater velocity (V) and land use type (L) were picked up to compose the index system. And then the accuracy of vulnerability mapping was discussed by a group of integrated indicators, including the corresponding relationship between the extreme nitrate concentration and the vulnerability classes, F statistic and class difference between the groundwater vulnerability classification and concentration classification of NO(3)-N. The optimized model graded by geometrical interval method improved the correlation between vulnerability index and nitrate concentration to the order of 0.6698 which was 0.4098 higher than that by the DRASTIC model. By level difference calculation, the correct vulnerability regions accounted for 64.45% of the study area. Lastly, sensitivity analyses indicated that the soil media and groundwater velocity were the most critical factors affecting groundwater vulnerability to nitrate. In short, RSIVL model was suitable to assess the groundwater vulnerability to nitrate in the study area with readily available hydrogeological and hydrochemical data. Hence, the mapping of groundwater vulnerability to nitrate can be applied for sensible groundwater resource management and land use planning., (Copyright © 2012 Elsevier B.V. All rights reserved.)

A framework for characteristics identification and source apportionment of water pollution in the Jinjiang River of China was proposed in this study for evaluation. A total of 114 water samples which were generated between May 2009 and September 2010 at 13 sites were collected and analysed. First, support vector machine (SVM) and water quality pollutant index (WQPI) were used for water quality comprehensive evaluation and identifying characteristic contaminants. Later, factor analysis with nonnegative constraints (FA-NNC) was employed for source apportionment. Finally, multi-linear regression of the absolute principal component score (APCS/MLR) was applied to further estimate source contributions for each characteristic contaminant. The results indicated that the water quality of the Jinjiang River was mainly at the third level (65.79%) based on national surface water quality permissible standards in China. Ammonia nitrogen, total phosphorus, mercury, iron and manganese were identified as characteristic contaminants. Source apportionment results showed that industrial activities (63.16%), agricultural non-point source (16.50%) and domestic sewage (12.85%) were the main anthropogenic pollution sources which were influencing the water quality of Jinjiang River. This proposed method provided a helpful framework for conducting water pollution management in aquatic environment.

Bioavailable vanadium was evaluated on the basis of soil vanadium single-extraction with ethylenediaminetetraacetic acid (EDTA), hydrochloric acid (HCl), acetic acid (HOAc), and sodium nitrate (NaNO(3)) in Panzhihua urban park. The soil vanadium concentration extracted by HOAc was 0.01-2.07 mg kg(-1), by EDTA 0.28-7.03 mg kg(-1), by NaNO(3) 0.07-0.53 mg kg(-1), and by HCl 0.19-1.36 mg kg(-1). The bioavailable vanadium (bioavailable fraction) obtained with HOAc was 0.01-1.33%, with EDTA 0.27-4.09%, with NaNO(3) 0.13-0.72%, and with HCl 0.06-0.28%. In addition, the impact of soil properties, soil nutrients, and soil enzyme activities on bioavailability of vanadium is discussed in this study. Based on the characteristics of bioavailable vanadium in the soil, ecological and health risks should have been given more attention in the studied area.

In order to characterize uptake of vanadium in alfalfa grown in vanadium-cadmium (Cd)-contaminated soil, 104 soil samples and 94 plant samples were collected from pot experiment. The results showed alfalfa had strong metal adaptability (up to 400 mg kg(-1)) and high accumulation (up to 3,440.14 mg kg(-1)) of vanadium. Root had higher contents and better absorption to vanadium than overground part. Moreover, both root and overground part had direct correlation with vanadium in soil, especially with the sum of first three fractions and reducible fraction. With the increasing of vanadium, higher concentration of Cd may inhibit the absorption of vanadium in alfalfa.

In order to characterize environmental vanadium distribution, mobility, and bioaccumulation, a total of 55 soil samples and 36 plant samples were collected in four typical land-use districts in Panzhihua region, Southwestern China. Soil samples were analyzed with the modified Community Bureau of Reference (BCR) sequential extraction procedure, and the content of vanadium in soil and plant was determined by ICP-AES. The total content of vanadium was 208.1-938.4 mg kg(-1) in smelting area, 111.6-591.2 mg kg(-1) in mining area, 94.0-183.6 mg kg(-1) in urban park, and 71.7-227.2 mg kg(-1) in agricultural area, respectively, while the bio-available content of vanadium was characterized that the polluted areas (mining area 18.8-83.6 mg kg(-1), smelting area 41.7-132.1 mg kg(-1)) and the unpolluted area (agricultural area 9.8-26.4 mg kg(-1), urban park 9.9-25.2 mg kg(-1)). In addition, the contamination degree of vanadium in soil was smelting area > mining area > agricultural area ≈ urban park. Moreover, the fraction of vanadium in each sequential extraction characterized that residual fraction > oxidizable fraction > reducible fraction > acid soluble fraction. The bioaccumulation of vanadium from soil to plant was weak to intermediate absorption. Therefore, some countermeasures such as soil monitoring and remediation should be to take in the sooner future, especially in mining and smelting area.

In order to measure groundwater age and design nuclear waste disposal sites, it is important to understand the sorption behavior of tritium on soils. In this study, batch tests were carried out using four soils from China: silty clays from An County and Jiangyou County in Sichuan Province, both of which could be considered candidate sites for Very Low Level Waste disposal; silty sand from Beijing; and loess from Yuci County in Shanxi Province, a typical Chinese loess region. The experimental results indicated that in these soil media, the distribution coefficient of tritium is slightly influenced by adsorption time, water/solid ratio, initial tritium specific activity, pH, and the content of humic and fulvic acids. The average distribution coefficient from all of these influencing factors was about 0.1-0.2 mL/g for the four types of soil samples. This relatively modest sorption of tritium in soils needs to be considered in fate and transport studies of tritium in the environment., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

The research utilized Bidens maximowicziana along with pyrene-degrading bacteria to evaluate their potential in cleaning up pyrene contamination. The removal of pyrene from the planted soil was obviously higher than that from the unplanted soils. After 50 d of B. maximowicziana growth, the average removal ratio of pyrene in planted soil was 79%, which was 28% higher than that of pyrene in unplanted soil. In contrast to other plants, both roots and shoots of B. maximowicziana could accumulate a large amount of pyrene from the soil and pyrene uptake increased with the soil pyrene concentration. Through analysis of pathways of pyrene removal, this enhanced removal of pyrene by plant-microbial association might be mainly the result of B. maximowicziana-promoted microbial degradation. Both the catalase and polyphenol oxidase activities in soil were higher in planted soil than those in unplanted soil. And the bacteria populations in soil, especially in rhizosphere, were also inspired by the growth of B. maximowicziana. These could be explained by the rhizosphere effect. Therefore, bio-removal of pyrene in the contaminated soils was feasible using B. maximowicziana., (Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.)