An integrated multimedia fate modeling framework for identifying mitigation strategy of antibiotic ecological risks: A case study in a peri-urban river.

Antibiotics have been heavily used over the past decades, resulting in their frequent detections in rivers and increasing ecological risks. Recognizing characteristics of antibiotic ecological risks (AERs) and making effective strategies to mitigate the AERs are essential to ensure the safety of aquatic ecosystem and public health. In this study, an integrated technological framework has been proposed toward identifying management options for reducing AERs by jointly utilizing multimedia fugacity modelling and ecotoxicological risk assessment, and applied to characterize the AERs in a peri-urban river in Beijing. Specifically, a level III fugacity model has been successfully established to simulate the fate of antibiotics in the environment, and the manageable parameters have been screened out via sensitivity analysis of the model. Then the validated fugacity model has been used for scenario modellings to optimize mitigation strategies of AERs. Results show most of the antibiotics considered are frequently detected in the river, and pose medium or high risks to aquatic organisms. Relatively, the macrolides and fluoroquinolones present higher ecotoxicological risks than sulfonamides and tetracyclines. Furthermore, the mixture risk quotient and predictive equation of concentration addition suggest joint and synergistic/antagonistic effects of AERs for multiple or binary antibiotics in the environment. Largely, the concentrations of antibiotics in the river are determined by the source emissions into water and soil. Scenario modellings show the improvement of antibiotic removal rates would be considered preferentially to mitigate the AERs. Also, controlling human consumption is conducive to reducing the risks posed by tetracyclines, macrolides and trimethoprim, while controlling animal consumption would benefit the reduction for sulfonamides. Overall, the joint strategy presents the greatest reduction of AERs by reducing antibiotic consumption and together improving sewage treatment rate and antibiotic removal rate. The study provides us a useful guideline to make ecological risk-based mitigation strategy for reducing AERs in environment.

Microcosm experiments revealed resistome coalescence of sewage treatment plant effluents in river environment.

Sewage treatment plant (STP) effluents are important contributors of antibiotic resistance (AR) pollution in rivers. Effluent discharging into rivers causes resistome coalescence. However, their mechanisms and dynamic processes are poorly understood, especially for the effects of dilution, diffusion, and sunlight-induced attenuation on coalescence. In this study, we have constructed microcosmic experiments based on in-situ investigation to explore these issues. The first batch experiment revealed the effects of dilution and diffusion. The coverage of water coalesced resistomes ranged 66.26∼152.18 × /Gb and was positively correlated with effluent volume (Mann-Kendall test, p < 0.01). Principal coordinate analysis (PCoA) and source tracking analysis demonstrated that dilution and diffusion stepwise reduced AR pollution. The second batch experiment explored the temporal dynamics and sunlight attenuation on coalesced resistomes. Under natural light, the coverage and diversity of water resistomes posed decreasing trends, primarily attributed to drastic erasure of effluent traces. The proportion of effluent-specific ARGs in coalesced resistomes significantly declined over time (Spearman's r = -0.83 and -0.94 in coverage and richness). While under dark condition, the coverage and diversity increased. Sunlight radiation intensified the interactions between water and sediment resistomes, as evidenced by more shared ARGs and less dissimilarities across niches. Network analysis, metagenome-assembled genome (MAG) analysis and variation partitioning analysis (VPA) showed that microbiome controlled resistome coalescence, explaining 56.5% and 58.4% of resistomes in water and sediment, respectively. Biotic and abiotic factors synergistically explained 40% of water resistomes. This study offers a comprehensive understanding of AR transmission and provides theoretical bases for grasping AR pollution and developing effective suppression strategies.

Risk characteristics of resistome coalescence in irrigated soils and effect of natural storage of irrigation materials on risk mitigation.

Irrigation and fertilization are the routinely agricultural practices but also cause resistome coalescence, by which the entire microbiomes from irrigation materials invade soil microbial community, to transfer antibiotic resistance genes (ARGs) in the coalesced soils. Although studies have reported the effect of irrigation or fertilization on the prevalence and spread of ARGs in soils, risk characteristics of resistome coalescence in irrigation system remain to be demonstrated and few has shown whether natural storage of irrigation materials will reduce resistance risks. To fill the gaps, two microscopic experiments were conducted for deeply exploring resistance risks in the soils irrigated with wastewater and manure fertilizer from a perspective of community coalescence by metagenomic analysis, and to reveal the effect of natural storage of irrigation materials on the reduction of resistance risks in the coalesced soils. Results showed irrigation and coalescence significantly increased the abundance and diversity of ARGs in the soils, and introduced some emerging resistance genes into the coalesced community, including mcr-type, tetX, qacB, and an array of genes conferring resistance to carbapenem. Procrustes analysis demonstrated microbial community was significantly correlated with the ARGs in coalesced soils, and variance partitioning analysis quantified its dominant role on shaping resistome profile in the environment. Besides ARGs, abundant and diverse mobile genetic elements (MGEs) were also identified in the coalesced soils and co-existed on the ARG-carrying contigs, implying potential transfer risk of ARGs in the irrigation system. Further, the analysis of metagenome-assembled genomes (MAGs) confirmed the risk by recovering 358 ARGs-carrying MAGs and identifying the resistant bacteria that co-carried multiple ARGs and MGEs. As expected, the natural storage of irrigation water and manure fertilizer reduced about 27%-54% of ARGs, MGEs and virulence factors in the coalesced soils, thus caused the soils to move towards lower resistance risks to a certain extent.

Meta-analysis addressing the characterization and risk identification of antibiotics and antibiotic resistance genes in global groundwater.

Antimicrobial resistance (AMR) is one of the significant global issues to public health. Compared to other aquatic environments, research on AMR in groundwater is scarce. In the study, a meta-analysis was conducted to explore the characteristics and risks of antibiotics and antibiotic resistance genes (ARGs) in global groundwater, using a data set of antibiotic concentrations collected from publications during 2000-2021 and a large-scale metagenomes of groundwater samples (n = 330). The ecotoxicological risks of antibiotics in the global groundwater were evaluated using mixture risk quotient with concentration addition model to consider the synergistic effects of multiple antibiotics. Bioinformatic annotations identified 1413 ARGs belonging to 37 ARG types in the global groundwater, dominated by rifamycin, polyketide, and quinolone resistance genes and including some emerging ARGs such as mcr-family and carbapenem genes. Relatively, the level of ARGs in the groundwater from spring was significantly higher (ANOVA, p < 0.01) than those from the riparian zone, sand and deep aquifer. Similarly, metal resistance genes (MRGs) were prevalent in the global groundwater, and network analysis suggested the MRGs presented non-random co-occurrence with the ARGs in such environments. Taxonomic annotations showed Proteobacteria, Actinobacteria, Eukaryota, Acidobacteria and Thaumarchaeota were the dominant phylum in the groundwater, and the microbial community largely shaped profile of ARGs in the environment. Notably, the ARGs presented co-occurrence with mobile genetic elements, virulence factors and human bacterial pathogens, indicating potential dissemination risk of ARGs in the groundwater. Furthermore, an omics-based approach was used for health risk assessment of antibiotic resistome and screened out 152 risk ARGs in the global groundwater. Comparatively, spring and cold creek presented higher risk index, which deserves more attention to ensure the safety of water supply.

Spectroscopic Characteristics and Speciation Distribution of Fe(III) Binding to Molecular Weight-Dependent Standard Pahokee Peat Fulvic Acid.

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.

Effects on microbiomes and resistomes and the source-specific ecological risks of heavy metals in the sediments of an urban river.

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.

TDCPP mimics thyroid hormones associated with the activation of integrin αvß3 and ERK1/2.

Tri(1,3-dichloropropyl) phosphate (TDCPP) potentially damages the thyroid system in humans and animals. However, knowledge of its toxic effects and underlying mechanisms is limited. The present study was conducted to determine the thyroid hormone-disrupting effects of TDCPP and its major metabolite, bis(1,3-dichloro-2-propyl) phosphate (BDCPP) in rat pituitary cell lines (GH3). TDCPP and BDCPP, that mimic the thyroid hormone (TH), promoted GH3 cell proliferation and modulated the progression of the cell cycle at 20 and 200 µmol/L, respectively. Similar to T3, TDCPP and BDCPP also significantly upregulated c-fos and downregulated Tshß gene expression. Although the binding affinity of these chemicals for thyroid receptor ß (TRß) was not measured, significant competition between these chemicals to bind to the membrane thyroid hormone receptor (integrin αvß3) was found, suggesting that TDCPP and BDCPP were strongly bound to integrin αvß3. Results from a molecular docking analysis provided further evidence of strong binding affinities of TDCPP and BDCPP for integrin αvß3, and the ligand binding site of Arg-Gly-Asp (RGD) was identified. Real-time PCR also supported the supposition that, after binding to integrin αvß3, TDCPP and BDCPP may induce the activation of the extracellular signal-regulated protein kinase (ERK1/2) signal transduction pathway. Taken together, our data suggest that TDCPP and BDCPP have the ability to mimic THs and that the underlying mechanism might be associated with their interactions with integrin αvß3 and the activation of the ERK1/2 pathway, providing new insight into the mechanism of TDCPP- and BDCPP-induced cytotoxicity.

Characterization and source identification of antibiotic resistance genes in the sediments of an interconnected river-lake system.

Antimicrobial resistance has been a global public health concern. The river-lake systems are one of the tightly connected terrestrial ecosystems and, appear to be reservoirs of antibiotic resistant genes (ARGs) and dispersal routes of resistant pathogens because they are easily impacted by human activities. Currently, systematic knowledge on the prevalence, transfer risk and source of ARGs in river-lake systems is largely lacking. In this study, we focused on the high-throughput profiling and source-sink relationship disentangling of ARGs in the sediments of an interconnected river-lake system (Fuhe River and its receiving Lake Baiyang in northern China). To this end, 40 surface sediments were collected for metagenomic shotgun sequencing. The profile and co-occurrence of ARGs in the sediments of the river-lake system were comprehensively characterized, as well as the mobile genetic elements (MGEs) carrying ARGs and their potential resistome dissemination risk. CrAssphage, a recently-discovered bacteriophage, was used to track human fecal pollution on the prevalence of ARGs. Meanwhile, a novel fast expectation-maximization microbial source tracking (FEAST) method was combined with linear discriminant analysis effect size method (LEfSe) for quantitatively apportioning the contribution of river sediment to the presence of ARGs in the receiving lake. Results showed abundant and diverse ARGs (24 types consisting of 510 subtypes) were detected in the sediments of the river-lake system, including some emerging ARGs such as mcr-1, tetX and carbapenemases types. Network analysis suggested non-random co-occurrence patterns of ARGs within the same type and among different types. Importantly, a number of MGE-carrying contigs were identified with jointly containing one or more ARGs, resulting in higher resistome risk potential in Lake Baiyang than many worldwide lakes. Source tracking indicated the prevalence of ARGs in the sediments of the river-lake system might be largely explained by the extent of human fecal contamination, and apportionment estimates the load transport from Fuhe River contributed more than 80% of ARGs to the receiving Lake Baiyang.

Characterization and source apportionment of heavy metals in the sediments of Lake Tai (China) and its surrounding soils.

Heavy metals (HMs) in lake sediments have aroused long-term attention due to their persistent threat to the lake ecosystems. Study into the pollution characteristics and potential sources of HMs in lakes, especially those heavily influenced by human activities, can give some insights to prevent and control the environmental risks of HMs. Lake Tai is the China's third largest freshwater lake but has been a drastic example of water pollution in recent decades. Here, we systematically investigated the characterization of pollution, risk and sources of HMs in the sediments of Lake Tai and its surrounding soils using several methods and tools. Specifically, a total of 46 sediments and 578 soils were collected from the study area, and geochemical approaches (geo-accumulation index and enrichment factor) and pollution indexes were jointly used to reveal the contamination characteristics of HMs. Meanwhile, the potential ecological risk index and probabilistic model of health risk assessment were employed to understand the environmental risk of HMs. Further, absolute principle component score-multiple linear regression and positive matrix factorization models were comparatively applied to apportion the sources of HMs. Results showed that various metals including Cd, Cr, As, Hg, Pb, and Cu appeared contamination level in varying degrees both in the sediments and soils. In particular, Cd, As and Hg were identified as the significant contaminants and presented moderate ecological risk. As a whole, the health risk levels of metals were acceptable. Source apportionment suggested that industrial discharge, agricultural activities, atmospheric deposition and natural source were the potential origins of HMs in this area. Among them, anthropogenic activities were the largest dominator of HMs with contribution of >75%. The study will advance our knowledge on HMs in lake and its surrounding soils and provide reference for policy maker to design migration strategies for protecting the lake ecosystems.

Current status and associated human health risk of vanadium in soil in China.

A detailed assessment of vanadium contamination characteristics in China was conducted based on the first national soil pollution survey. The map overlay analysis was used to evaluate the contamination level of vanadium and the non-carcinogenic risk assessment model was calculated to quantify the vanadium exposure risks to human health. The results showed that, due to the drastically increased mining and smelting activities, 26.49% of soils were contaminated by vanadium scattered in southwest of China. According to Canadian soil quality guidelines, about 8.6% of the national soil pollution survey samples were polluted, and pose high non-carcinogenic risks to the public, especially to children living in the vicinity of heavily polluted mining areas. We propose the area near the boundary of Yunnan, Guizhou, Guangxi, and Sichuan provinces as priority control areas due to their higher geochemical background or higher health risks posed to the public. Finally, recommendations for management are proposed, including minimization of contaminant inputs, establishing stringent monitoring program, using phytoremediation, and strengthening the enforcement of relevant laws. Therefore, this study provides a comprehensive assessment of soil vanadium contamination in China, and the results will provide valuable information for China's soil vanadium management and risk avoidance.

Tracing Sources and Contamination Assessments of Heavy Metals in Road and Foliar Dusts in a Typical Mining City, China.

Road and foliar dust samples from four land-use districts of Panzhihua City, a famous V-Ti magnetite production area of China, were collected to investigate the sources and distribution characteristics of 9 heavy metals (V, Pb, Cd, Cu, Zn, Ni, Cr, Fe, and Mn). The results suggest that foliar samples had smaller particle size and higher heavy metal contents than road dusts. The contamination assessments of heavy metals were as follows: Pb and V (significant enrichment) > Zn, Ni, Cr, Fe, and Mn (moderate enrichment) > Cd and Ni (minimal enrichment). Statistical analyses showed Pb, as the primary pollution element, originated from waste incineration and lead-fuel combustion. The sources of Zn, Ni, Cr, Fe, V, and Mn were fugitive dust and traffic activities. Potential origins of Cu were corrosion of alloys used in vehicle components, vehicle covers, or other metallic surfaces and materials. The sources of Cd were different from any other heavy metals. Traffic and industrial activities were the main anthropogenic origins of heavy metals in dusts of Panzhihua, and more attention should be paid to heavy metal pollution in agricultural area.

Distribution, bioavailability, and potential ecological risk of Cu, Pb, and Zn in soil in a potential groundwater source area.

In this study, we examined three horizontal and vertical soil profiles along a sewage drainage ditch in order to determine the spatial distribution of Cu, Pb, and Zn in soils and to assess the bioavailability and potential ecological risks associated with these metals in a potential groundwater source area. Results showed that the concentrations of Cu, Pb, and Zn were approximately at background level, suggesting that human activities (industrial and agricultural pollution) had a negligible influence on these metals in soil, and that the concentrations reflected the natural background levels in the study area. Cu, Pb, and Zn concentrations were slightly higher in topsoil (0-20 cm) than deeper in the soil profile. Using a modified BCR sequential extraction method to evaluate the mobility and bioavailability of metals showed that the potential bioavailability sequence of Cu, Pb, and Zn at three depths in the soil profile was in the order Cu ≈ Pb < Zn. The potential ecological risk from the metals was evaluated using risk assessment code, and the results suggest that Cu and Zn pose no or low risk, while there is a low or medium risk from Pb. Results from groundwater monitoring showed that the groundwater was not polluted by leaching from soil.

Comparison of bioavailable vanadium in alfalfa rhizosphere soil extracted by an improved BCR procedure and EDTA, HCl, and NaNO3 single extractions in a pot experiment with V-Cd treatments.

The BCR sequential extraction procedure was compared with EDTA, HCl, and NaNO3 single extractions for evaluating vanadium bioavailability in alfalfa rhizosphere soil. The amounts of vanadium extracted by these methods were in the following order: BCR (bioavailable V) > EDTA ≈ HCl > NaNO3. Both correlation analysis and stepwise regression were adopted to illustrate the extractable vanadium between different reagents. The correlation coefficients between extracted vanadium and the vanadium contents in alfalfa roots were R NaNO3 = 0.948, R HCl = 0.902, R EDTA = 0.816, and R bioavailable V = 0.819. The stepwise multiple regression equation of the NaNO3 extraction was the most significant at a 95 % confidence interval. The influence of pH, total organic carbon, and cadmium content of soil to vanadium bioavailability were not definite. In summary, both the BCR sequential extraction and the single extraction methods were valid approaches for predicting vanadium bioavailability in alfalfa rhizosphere soil, especially the single extractions.

Soil and soil environmental quality monitoring in China: a review.

Over the past few decades, numerous concerns have been raised in China over the issue of environmental sustainability. Various soil survey and monitoring programs have been carried out in China to study soil quality, and to provide a scientific basis for environment policy making. This paper provides an overview of past and current soil quality surveys and monitoring activities in China. This paper includes a summary of concerns over background concentrations of elements in soil, and soil environmental standards and guidelines in China. Levels of pollution in urban soil, agricultural soil, and soil in mining and smelting areas were compared using the concentrations and pollution indexes. In addition to soil surveys, soil monitoring is essential to study the data and to examine the effects of contaminants in soils. However, the current soil quality monitoring system was insufficient to accurately determine the soil quality status of soils across China. For accurate soil monitoring in China, it will be necessary to set up routine monitoring systems at various scales (national, provincial, and local scales), taking into consideration monitoring indicators and quality assurance. This is currently an important priority for the environmental protection administration of China.

Characterization and source apportionment of water pollution in Jinjiang River, China.

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.

Total petroleum hydrocarbon distribution in soils and groundwater in Songyuan oilfield, Northeast China.

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.

Source apportionment of sediment PAHs in the Pearl River Delta region (China) using nonnegative matrix factorization analysis with effective weighted variance solution.

Considering the advantages and limitations of a single receptor model, in this study, a combined technique of nonnegative matrix factorization analysis with effective weighted variance solution (NMF-EWV) was proposed for source apportionment. Utilizing NMF, major linear independent factor loadings with nonnegative elements were extracted to identify potential pollution sources. Then, these physical reasonable factor loadings were regarded as source profiles to apportion contributions using effective weighted variance solutions. Evaluation results indicated that the NMF-EWV method reproduced the source profiles well, and got a reasonable apportionment results for the synthetic dataset. The methodology of the NMF-EWV was also applied to recognize sources and apportion the contributions of polycyclic aromatic hydrocarbons (PAHs) collected from freshwater and marine sediments in the Pearl River Delta (PRD) region which is one of the most industrialized and economically significant regions of China. Apportionment results showed that traffic tunnel made the largest contribution (46.49%) for the freshwater PAH sediments in the PRD, followed by coal residential source (29.61%), power plant (13.45%) and gasoline engine (10.45%). For the marine sediments, traffic tunnel was also apportioned as the largest source (57.61%), followed by power plant (22.86%), gasoline engine (17.71%) and coal residential source (1.82%). Traffic-related sources were the predominant reasons for PAH pollution in that region.

Source apportionment of trace element pollution in surface sediments using positive matrix factorization combined support vector machines: application to the Jinjiang River, China.

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 %).

Bioavailability of vanadium extracted by EDTA, HCl, HOAC, and NaNO3 in topsoil in the Panzhihua urban park, located in southwest China.

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.