Influence of dissolved organic matter on dissolved vanadium speciation in the Churchill River estuary (Manitoba, Canada)

Emerging hazardous chemicals and biological pollutants in Canadian aquatic systems and remediation approaches: A comprehensive status report

Emerging contaminants can be natural or synthetic materials, as well as materials of a chemical, or biological origin; these materials are typically not controlled or monitored in the environment. Canada is home to nearly 7 % of the world's renewable water supply and a wide range of different kinds of water systems, including the Great Lake, rivers, canals, gulfs, and estuaries. Although the majority of these pollutants are present in trace amounts (μg/L - ng/L concentrations), several studies have reported their detrimental impact on both human health and the biota. In Canadian aquatic environments, concentrations of pharmaceuticals (as high as 115 μg/L), pesticides (as high as 1.95 μg/L), bioavailable heavy metals like dissolved mercury (as high as 135 ng/L), and hydrocarbon/crude oil spills (as high as 4.5 million liters) have been documented. Biological threats such as genetic materials of the contagious SARS-CoV-2 virus have been reported in the provinces of Québec, Ontario, Saskatchewan and Manitoba provinces, as well as in the Nunavut territory, with a need for more holistic research. These toxins and emerging pollutants are associated with nefarious short and long-term health effects, with the potential for bioaccumulation in the environment. Hence, this Canadian-focused report provides the footprints for water and environmental sustainability, in light of this emerging threat to the environment and society. Several remediation pathways/tools that have been explored by Canadian researchers, existing challenges and prospects are also discussed. The review concludes with preventive measures and strategies for managing the inventory of emerging contaminants in the environment.

Bio-accessibility and mobilization dynamics of soil vanadium during a 48-year vegetation restoration in a vanadium titano-magnetite tailings reservoir

Bio-accessibility of vanadium (V) in soils determines the effectiveness of vegetation restoration in the vanadium titano-magnetite tailings reservoirs because of persistent V toxicity, yet the variations in the bio-accessibility and mobilization of V in the soils with vegetation restoration remain elusive. Here, the bio-accessibility and mobilization of V in the soil-water interface were investigated along a 48-year vegetation restoration chronosequence in the Majiatian tailings reservoir using the diffusive gradients in thin films technique (DGT) and DGT-induced flux model. We found a low concentration of DGT-extracted V along the vegetation restoration chronosequence and the V fraction was dominated by the residual form, indicating a low V bio-accessibility in the soils. The bio-accessibility of V increased along the chronosequence because of the increased V resupply from solid phase, especially from the organic V fraction and the clay bound V. Low supply coefficient (R = 0.25) revealed a limited release of V from solid phase to soil solution. The kinetic resupply processes of V and its key regulating parameters were stage-specific during the vegetation restoration. The pool size of labile V in the soils determined the rapid V supply at the early and late stages, while the low desorption rate of V from the solid to liquid phase regulated the slow supply regime at the middle stage. The results of the present study highlight the importance of the long-term monitoring of soil V mobilization in the tailings reservoir because of the increased bio-accessibility and the dynamic supply of V during the vegetation restoration.

Spatiotemporal characterization of vanadium at the sediment-water interface of a multi-ecological lake

As an emerging environmentally harmful metal, vanadium (V) deserves significant research attention due to its hazardous concentrations in aquatic environments. However, the research on the characterization of V in sediment-water interface (SWI) remains limited. In this study, seasonal sampling was conducted in algal- and macrophyte-dominated zones via the method of in situ high-resolution diffusive gradients in thin films (DGT). The concentration of dissolved V in water in algal-dominated regions (12 sites) exceeded the long-term ecotoxicology limit of 1.2 μg⋅L-1. Seasonal variations of chemical speciation of V were observed in three ecological sites. DGT-labile V at the SWI exhibited two basic patterns associated with eutrophic status, one showing sharply decreasing gradients in the vicinity of the SWI and the other showing the absence of diffusion gradient. Positive correlations were observed between the water-dissolved V and the DGT-labile V, indicating DGT-labile V is a sensitive indicator for the release of V from sediment into water. Moreover, the mobility of V was influenced by the reduction of Fe(hydr)oxides and complexation with organic matter, in particular, during periods of algal blooms. It is suggested that V contamination at the SWI of algal-dominated zones deserves additional attention.

Cyanobacterial blooms increase the release of vanadium through iron reduction and dissolved organic matter complexation in the sediment of eutrophic lakes

Vanadium (V), a hazardous environmental contaminant, can be highly toxic to aquatic or even human life. Nonetheless, knowledge of its redox geochemistry and mobility in sediments, especially those of eutrophic lakes, remains limited. In this study, we combined in situ high-resolution sampling and laboratory simulation experiments for monitoring soluble and labile V to reveal the mobilization mechanism of V in the sediment of Lake Taihu. The results showed that the concentration of soluble V (1.18-5.22 µg L-1) exceeded the long-term ecotoxicology limitation proposed by the government of the Netherlands. The highest value appeared in summer (July to September), with an average concentration of 3.87 µg L-1, which exceeded the short-term exposure limit. The remobilization of V in summer was caused by the combined effect of the reduction of Fe(hydr)oxides and dissolved organic matter (DOM) complexation, which accelerated the release of associated Fe-bound V and increased the solubility of DOM-V. Additionally, V showed high mobility in winter, owing to the species of V(Ⅲ)/V(Ⅳ) being oxidized to V(Ⅴ) with higher solubility. It is noteworthy that the elevated remobilization of V in sediments increases the risk of V release from sediments, which poses the threat of water V pollution in Lake Taihu.

Insights on metal pollution of a Patagonia watershed: A case study in the lower course of the Negro river, Argentina

This study evaluated the occurrence and distribution of largely known pollutants (Ag, Cd, Cu, Cr, Hg, Ni, Pb, Pd, and Zn), as well as emerging ones (Li, and V) in the water dissolved fraction, suspended particulate matter, and surface sediments from the lower course of the Negro River, Argentina. There are scarce preceding data on inorganic pollution in the entire watershed and, in the case of the emerging pollutants, there are almost no studies performed worldwide. Sampling was conducted in 2019 at six sampling sites, three of them mostly river dominated and the rest under marine domain. The samples were subjected to an acid digestion in a microwave digester, and analyzed using an Inductively Coupled Plasma Atomic Emission Spectrometer. Results: revealed that Cu, Li, V, and Zn were always on the top four of the highest average metal concentrations in water and sediment fractions. The pollution assessment indicated that the watershed might be exposed to anthropogenic pollution, as over 60% of Cu and Zn, and over 85% of Hg in water dissolved samples from the marine dominated sites were above the maximum recommended values from guidelines. The multivariate analyses characterized the watershed into two clusters, with metals in the sediment fraction mainly contributing to the uppermost sites. Indeed, sedimentary Cu and Zn background enrichment indices pointed out a moderate pollution of the river dominated sites. This study highlights the relevance of an integrative approach in metal pollution evaluation, as the results denoted a progressive deterioration of the watershed, affecting the water quality of the lower course of the Negro River and its adjacent coastal zone. Overall, these results contribute to a more complete evaluation of the potential to fulfill the Sustainable Development Goals, with implications for future treatment strategies to enhance the environmental quality of the area.

The key role of proteostasis at mitochondria-associated endoplasmic reticulum membrane in vanadium-induced nephrotoxicity using a proteomic strategy

Excessive vanadium (V) contamination is an attracting growing concern, which can negatively affect the health of human and ecosystems. But how V causes nephrotoxicity and the role of mitochondria-associated endoplasmic reticulum membrane (MAM) in V-induced nephrotoxicity have remained elusive. To explore the detailed mechanism and screen of potential effective drugs for V-evoked nephrotoxicity, a total of 72 ducks were divided into two groups, control group and V group (30 mg/kg V). Results showed that excessive V damaged kidney function of ducks including causing histopathological abnormality, biochemical makers derangement and oxidative stress. Then MAM of duck kidneys was extracted to investigate differentially expressed proteins (DEPs) under V exposure using proteomics analysis. Around 4240 MAM-localized proteins were identified, of which 412 DEPs showed dramatic changes, including 335 upregulated and 77 downregulated DEPs. On the basis of gene ontology (GO), string and KEGG database analysis, excessive V led to nephrotoxicity primarily by affecting MAM-mediated metabolic pathways, especially elevating the endoplasmic Reticulum (ER) proteostasis related pathway. Further validation analysis of the detected genes and proteins of ER proteostasis related pathway under V poisoning revealed a consistent relationship with proteome analysis, indicating that V disrupted MAM-mediated ER proteostasis. Accordingly, our data proved the critical role for MAM in V-evoked nephrotoxicity, particularly with MAM-mediated ER proteostasis, providing promising insights into the toxicological exploration mechanisms of V.

Vanadate Retention by Iron and Manganese Oxides

Anthropogenic emissions of vanadium (V) into terrestrial and aquatic surface systems now match those of geogenic processes, and yet, the geochemistry of vanadium is poorly described in comparison to other comparable contaminants like arsenic. In oxic systems, V is present as an oxyanion with a +5 formal charge on the V center, typically described as H x VO4 (3-x)-, but also here as V(V). Iron (Fe) and manganese (Mn) (oxy)hydroxides represent key mineral phases in the cycling of V(V) at the solid-solution interface, and yet, fundamental descriptions of these surface-processes are not available. Here, we utilize extended X-ray absorption fine structure (EXAFS) and thermodynamic calculations to compare the surface complexation of V(V) by the common Fe and Mn mineral phases ferrihydrite, hematite, goethite, birnessite, and pyrolusite at pH 7. Inner-sphere V(V) complexes were detected on all phases, with mononuclear V(V) species dominating the adsorbed species distribution. Our results demonstrate that V(V) adsorption is exergonic for a variety of surfaces with differing amounts of terminal -OH groups and metal-O bond saturations, implicating the conjunctive role of varied mineral surfaces in controlling the mobility and fate of V(V) in terrestrial and aquatic systems.

Vanadium: A Review of Different Extraction Methods to Evaluate Bioavailability and Speciation

The excessive input of heavy metals such as vanadium (V) into the environment has been one of the consequences of global industrial development. Excessive exposure to V can pose a potential threat to ecological safety and human health. Due to the heterogeneous composition and reactivity of the various elements in soils and sediments, quantitative analysis of the chemical speciation of V in different environmental samples is very complicated. The analysis of V chemical speciation can further reveal the bioavailability of V and accurately quantify its ecotoxicity. This is essential for assessing for exposure and for controlling ecological risks of V. Although the current investigation technologies for the chemical speciation of V have grown rapidly, the lack of comprehensive comparisons and systematic analyses of these types of technologies impedes a more comprehensive understanding of ecosystem safety and human health risks. In this review, we studied the chemical and physical extraction methods for V from multiple perspectives, such as technological, principle-based, and efficiency-based, and their application to the evaluation of V bioavailability. By sorting out the advantages and disadvantages of the current technologies, the future demand for the in situ detection of trace heavy metals such as V can be met and the accuracy of heavy metal bioavailability prediction can be improved, which will be conducive to development in the fields of environmental protection policy and risk management.

Labile metal assessment in water by diffusive gradients in thin films in shipyards on the Brazilian subtropical coast

Shipyards impact on estuarine environments because of the use of antifouling paints and petroleum products, which release trace metals that may remain in their bioavailable or labile form. Regardless of its importance, the relation between continuous input of trace metals (hotspot area) and their availability in the water column has been scarcely studied. This study evaluated seasonal variations in the concentrations of labile fractions of metals in shipyards located in estuarine areas on the Brazilian subtropical coast. These fractions were determined by the Diffuse Gradients in Thin Films (DGT) technique. Maximum labile fraction concentrations of Cr (0.3 μg L^-1), Ni (2.2 μg L^-1) and V (2.0 μg L^-1) are directly related to (i) their specific source: antifouling paints (for Cr), metal and steel alloys (for Cr and Ni) and petroleum products (for V), besides (ii) periods of intensive traffic and vessel repair. Additionally, variations in labile fractions of Ni and V in the Patos Lagoon estuary were influenced by salinity, which is known to affect metal desorption from surface sediments in resuspension events. Even though Cr is affected by the same processes, it is available as Cr(III) and does not represent any ecological risk in the study areas. Although the areas under study are affected by variations in physical and chemical conditions, shipyards were effectively hotspots of trace metals in their labile fraction in various estuarine systems in southeastern and southern Brazil. Thus, they represent areas where Ecological Risk Assessment, mainly of V, should be carried out.

Redox Speciation of Vanadium in Estuarine Waters Using Improved Methodology Based on Anion Exchange Chromatography Coupled to HR ICP-MS System

An improved methodology was developed for V redox speciation in estuarine waters using a hyphenated technique consisting of ion chromatograph (IC) with an anion exchange column and a high-resolution inductively coupled plasma mass spectrometer (HR ICP-MS). This approach enables the direct determination of V(V), whereas reduced species (mainly V(IV)) are calculated by subtracting V(V) concentrations from the measured total V concentration. Based on the “on-column” V(V) chelation mechanism by EDTA, with the eluent composed of 40 mmol L⁻¹ ammonium bicarbonate, 40 mmol L⁻¹ ammonium sulphate, 8 mmol L⁻¹ ethylenediaminetetraacetic acid and 3% acetonitrile, the method was successfully used for analyses of V redox speciation in samples taken in the vertical salinity gradient of the highly stratified Krka River estuary. Due to the matrix effects causing different sensitivities, a standard addition method was used for V(V) quantification purposes. The limit of detection (LOD) was also found to be matrix related: 101.68 ng L⁻¹ in the seawater and 30.56 µg L⁻¹ in the freshwater. Performed stability tests showed that V redox speciation is preserved at least 7 days in un-treated samples, possibly due to the stabilization of V-reduced species with natural organic matter (NOM). The dominant V form in the analysed samples was V(V) with the reduced V(IV) accounting for up to 26% of the total dissolved pool. The concentration of V(IV) was found to correlate negatively with the oxygen concentration. Significant removal of dissolved V was detected in oxygen depleted zones possibly related to the particle scavenging.

Application of Fourier transform ion cyclotron resonance mass spectrometry to characterize natural organic matter

Advances in the ultra-high-resolution mass spectroscopy lead to a deep insight into the molecular characterization of natural organic matter (NOM). Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) has been used as one of the most powerful tools to decipher NOM molecules. In FTICR-MS analysis, the matrix effects caused by the co-occurring inorganic substances in water samples greatly affect the ionization of NOM molecules. The inherent complexity of NOM may hinder its component classification and formula assignment. In this study, basic principles and recent advances for sample separation and purification approaches, ionization methods, and the evolutions in formula assignment and data exploitation of the FTICR-MS analysis were reviewed. The complementary characterization methods for FTICR-MS were also reviewed. By coupling with other developed/developing characterization methods, the statistical confidence for inferring the NOM compositions by FTICR-MS was greatly improved. Despite that the refined separation procedures and advanced data processing methods for NOM molecules have been exploited, the big challenge for interpreting NOM molecules is to give the basic structures of them. Online share of the FTICR-MS data, further optimizing the FTICR-MS technique, and coupling this technique with more characterization methods would be beneficial to improving the understanding of the composition and property of NOM.

Establishment of geochemical baseline and multiple assessment of vanadium pollution in sediment cores from the two cascade reservoirs, North China

Vanadium (V) is a potential toxic pollutant, and thus, V pollution in reservoir sediment should be scientifically evaluated because reservoirs are the main source of drinking water in China. However, the pollution assessment of V in reservoir sediment is often overestimated or underestimated due to the limitation for selecting local background values. In this study, the selection of the V background value in sediments was based on regional geochemical baseline (RGB) model. Multiple methods including geo-accumulation index (I_geo), potential ecological risk index (EI), and health risk assessment were applied to evaluate V pollution in sediment cores collected from the Panjiakou-Daheiting Reservoirs (PDR). The results show that the mean value of V concentrations in the PDR sediment cores was 92.86 mg/kg (57.69-141.19 mg/kg), which is higher than the soil background in Hebei Province and stream sediment values in China. V concentrations in the Panjiakou Reservoir were higher than those in the Daheiting Reservoir. The RGB value of V was 96.33 mg/kg in the PDR sediments. A comparison of the V concentrations and RGB values in the sampling sites indicated that half of these sites are impacted by anthropogenic inputs. Among the sites influenced by human activity, the average anthropogenic contribution was 9.9%, suggesting that majority of V in the PDR sediments originated from natural source. The pollution assessments of V were evaluated using I_geo and EI with RGB as the background value, and results indicated that the sediments in the PDR were not polluted with V. The environmental impact assessment model was also established for calculating V accumulation in fish due to sediment resuspension. Then, health risk assessment model was applied to further calculate the health risk to residents due to fish consumption. The evaluated target hazard quotient demonstrated that local fish consumption produced no adverse effect on human health during sediment disruption.

Linking molecular and optical properties of dissolved organic matter across a soil-water interface on Akimiski Island (Nunavut, Canada)

Dissolved organic matter (DOM) plays a crucial role in terrestrial and aquatic carbon and biogeochemical cycles; however, molecular transformations between aquatic and terrestrial systems remain poorly understood due to the complexity and heterogeneity of DOM. In this study, we investigated the molecular diversity of aquatic DOM and adjacent soil derived water extractable organic matter (WEOM) from seven locations on Akimiski Island, Nunavut using a combination of absorbance spectroscopy and Fourier transform ion cyclotron mass spectrometry (FT-ICR-MS). Assigned elemental formula and Van Krevelen compositional analysis reveal compositional similarities in river, inland ponds and coastal pool sites for aquatic DOM and WEOM. More aromatic, oxygenated polyphenolic carbon rich molecules were found in aquatic DOM whereas WEOM was abundant in highly unsaturated aliphatic material. A total of 276 phenolic, unsaturated aliphatic, and vascular plant-derived polyphenolic molecules were identified as being conserved between WEOM and aquatic DOM at one river and two inland pond locations suggesting similar CHO sources from adjacent soils. Moreover, contributions of polyphenolic compounds in aquatic DOM and WEOM were greater at inland ponds than coastal pools, congruent with a greater aromaticity at inland sites. Our results highlight the similarities and differences in WEOM to aquatic DOM composition and how they range across surrounding watersheds that provide insight into the biogeochemical dynamics across a Canadian subarctic terrestrial-aquatic-continuum.

Redox chemistry of vanadium in soils and sediments: Interactions with colloidal materials, mobilization, speciation, and relevant environmental implications- A review

Vanadium (V), although serving as an important component of industrial activities, has bioinorganic implications to pose highly toxic hazards to humans and animals. Soils and sediments throughout the world exhibit wide ranges of vanadium concentrations. Although vanadium toxicity varies between different species, it is mainly controlled by soil redox potential (E_H). Nonetheless, knowledge of the redox geochemistry of vanadium lags in comparison to what is known about other potentially toxic elements (PTEs). In particular, the redox-induced speciation and mobilization of vanadium in soils and sediments and the associated risks to the environment have not been reviewed to date. Therefore, this review aims to address 1) the content and geochemical fate of vanadium in soils and sediments, 2) its redox-induced release dynamics, 3) redox-mediated chemical reactions between vanadium and soil organic and inorganic colloidal materials in soil solution, 4) its speciation in soil solution and soil-sediments, and 5) the use of advanced geochemical and spectroscopic techniques to investigate these complex systems. Vanadium (+5) is the most mobile and toxic form of its species while being the thermodynamically stable valence state in oxic environments, while vanadium (+3) might be expected to be predominant under euxinic (anoxic and sulfidic) conditions. Vanadium can react variably in response to changing soil E_H: under anoxic conditions, the mobilization of vanadium can decrease because vanadium (+5) can be reduced to relatively less soluble vanadium (+4) via inorganic reactions such as with H₂S and organic matter and by metal-reducing microorganisms. On the other hand, dissolved concentrations of vanadium can increase at low E_H in many soils to reveal a similar pattern to that of Fe, which may be due to the reductive dissolution of Fe(hydr)oxides and the release of the associated vanadium. Those differences in vanadium release dynamics might occur as a result of the direct impact of E_H on vanadium speciation in soil solution and soil sediments, and/or because of the E_H-dependent changes in soil pH, chemistry of (Fe)(hydr)oxides, and complexation with soil organic carbon. Release dynamics of vanadium in soils may also be affected positively by soil pH and the release of aromatic organic compounds. X-ray absorption spectroscopy (XAS) is a powerful tool to investigate the speciation of vanadium present in soil. X-ray absorption near edge structure (XANES) is often used to constrain the average valence state of vanadium in soils and sediments, and in limited cases extended X-ray absorption fine structure (EXAFS) analysis has been used to determine the average molecular coordination environment of vanadium in soil components. In conclusion, this review presents the state of the art about the redox geochemistry of vanadium and thus contributes to a better understanding of the speciation, potential mobilization, and environmental hazards of vanadium in the near-surface environment of uplands, wetlands, and agricultural ecosystems as affected by various colloidal particles. Further research is needed to elucidate the geochemistry and speciation of vanadium in the dissolved, colloidal, and soil sediments phases, including the determination of factors that control the redox geochemistry of vanadium.

In situ arsenic speciation and the release kinetics in coastal sediments: A case study in Daya Bay, South China Sea

In-situ study on arsenic speciation and the release kinetics in marine sediments was scarce. In this study, the distributions of labile As and their speciation in coastal sediments of Daya Bay were obtained by separate diffusive gradients in thin films (DGT) probes. Results showed that the DGT-labile As(V) was the main speciation in surface sediments (from -20 to 0 mm) with a concentration range of 0.07-3.05 μg·L^-1, while the labile As(III) was the main speciation in deep layers of sediments (from -100 to -20 mm). In coastal areas, mariculture farms was the most dominated contributor to As(V) contamination in surface sediments. Both the apparent diffusion flux estimation and the DGT induced flux in sediments (DIFS) simulation indicated that As(V) contamination in surface sediments of mariculture, harbor and petrochemical areas suffered the potential risk of As(V) release into the overlying water from sediments. DIFS modeling also found that the sediments of mariculture farms were the main sediment As pools. Linear regression analysis indicated that the mobility of As mainly attributed to the As(V) in sediments.

Assessing cadmium and vanadium accumulation using diffusive gradient in thin-films (DGT) and phytoplankton in the Churchill River estuary, Manitoba

Diffusive gradient in thin films (DGT) and phytoplankton communities were evaluated for the measurement of Cd and V at environmentally relevant concentrations in laboratory settings and in the Churchill River estuary (Manitoba, Canada) during an annual spring melt. Despite rapid changes in hydrology and water quality, DGT samplers and intracellular Cd and V concentrations were positively correlated (0.79 < r(2) < 0.99), suggesting comparable accumulation trends between both DGT-labile and intracellular monitoring techniques. The largest accumulated concentrations of both Cd and V by DGT and phytoplankton accumulation methods were found later into the river discharge period. In controlled settings, accumulated Cd and V concentrations by the diatom Attheya septentrionalis displayed a strong correlation with metals accumulated by DGTs (r(2) > 0.99). Principal component analysis (PCA) reinforced similarities between both metal monitoring techniques and assessed how changing environmental variables during the river discharge period influenced each monitoring technique. Cd accumulation was influenced by DOC concentrations and protein-like DOM whereas ionic strength (i.e. conductivity) and humic-like DOM influenced V accumulation. The present findings suggest that (1) DGT is a versatile tool for monitoring bioaccumulation of Cd and V in highly dynamic environmental systems and (2) DOC concentration, DOM composition, conductivity, pH, and river discharge influence the bioavailability of Cd and V in estuarine and riverine waters.