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Abstract The activity of e-waste recycling often causes the combined pollution of tetrabromobisphenol A (TBBPA) and cadmium (Cd) in soils. In this study, the effects of their co-existence on each other's fate, further reflecting the bioavailability, were analyzed in the presence of two ecologically different earthworm species, endogeic Metaphire guillelmi and epigeic Eisenia fetida. Mineralization of 14C-TBBPA combined with 10 mg Cd kg−1 was suppressed by the presence of M. guillelmi , whereas a facilitating effect was produced by the combination of 1 mg Cd kg−1 in the soil- E. fetida system after a 14-day exposure. The uptake of 14C-TBBPA by M. guillelmi (17% of initial amount) and by E. fetida (10%) dominantly contributed to significant (P < 0.05) decrease of extractable (more bioavailable) 14C residues in soils both with and without Cd spiked, while the mineralization of 14C-TBBPA in the soils was negligible (<0.4%). Meanwhile the amendments of the two earthworm species exerted different impact on 14C distribution in bound residues. In general, co-exposure to Cd did not significantly (P > 0.05) influence the accumulation and metabolism of TBBPA in the earthworms. Both earthworms accumulated only ~7% of Cd in soil, however, the bioavailable Cd determined by the diffusive gradients in thin films technique declined by ~46% in the presence of M. guillelmi , and a much smaller decrease was determined in the presence of E. fetida. Amendment of TBBPA at environmental levels did not alter the accumulation and subcellular distribution of Cd in both earthworms unless that at high doses. The results highlighted the importance of considering the difference of the earthworm species and the interaction of pollutants in soil-risk assessments of such combined contamination. Capsule M. guillelmi displayed greater effect on the fate of TBBPA and Cd co-existed in soils than E. fetida , while the accumulation, metabolism, or distribution of the two pollutants in earthworms did not significantly alter due to interactions between the two pollutants. Graphical abstract Unlabelled Image Highlights • The amendments of Cd and earthworms affected TBBPA mineralization and residues. • Cd amendment did not alter accumulation and metabolism of TBBPA in two earthworms. • M. guillelmi amendment caused a larger decrease in Cd bioavailability. • TBBPA at high dose affected subcellular distribution of Cd in M. guillelmi. • M. guillelmi displayed a stronger bioturbation on pollutants' fate than E. fetida. [ABSTRACT FROM AUTHOR]

Abstract Cadmium (Cd) and tetrabromobisphenol A (TBBPA) are two ubiquitous pollutants in soils and are often found together at electronic waste recycling sites. In this study, their toxicity as well as the accumulation and subcellular partitioning of Cd were determined in two ecologically different earthworms Eisenia fetida and Metaphire guillelmi exposed for 14 days to Cd (1 mg kg−1) and TBBPA (10, 50, 100, and 500 mg kg−1) alone and in combination. In general, Cd-TBBPA co-exposure resulted in synergistic effects in terms of acute toxicity, growth inhibition, histopathological changes in body walls, and oxidative stress responses to earthworms, moreover, M. guillelmi showed higher sensitivity than E. fetida. Principal component analysis showed that the two earthworm species differed in their biomarker expression patterns. In addition, Cd accumulation was significantly (P < 0.01) reduced in E. fetida co-exposed to TBBPA but significantly (P < 0.05 and 0.01) enhanced in M. guillelmi. The difference in bioaccumulation between the two earthworm species may be made by their different exposure routes despite the decrease of Cd bioavailability (assessed by the diffusive gradients in thin films technique) in the soils. High doses of TBBPA also altered the subcellular distribution of Cd in the earthworms. These findings demonstrate the need to include more ecologically relevant earthworm species, represented in this study by M. guillelmi , in soil risk assessments of Cd and TBBPA co-exposure. Graphical abstract Image 1 Highlights • M. guillelmi showed higher sensitivity than E. fetida to Cd and TBBPA co-exposure. • The two earthworm species differed in the pattern of oxidative stress responses. • TBBPA addition inhibited Cd uptake in E. fetida due to Cd bioavailability decrease. • More Cd accumulated in M. guillelmi in the presence of TBBPA. • The high dose of TBBPA altered Cd subcellular partitioning in earthworms. Capsule : Metaphire guillelmi co-exposed to Cd and TBBPA displayed a higher sensitivity than Eisenia fetida and differed in its accumulation and subcellular partitioning of Cd. [ABSTRACT FROM AUTHOR]

Metal partitioning in soils is a key process controlling metal bioavailability and mobility and is greatly influenced by the solid/liquid ratio. However, metal partitioning is difficult to describe either by a simple partition coefficient or by isotherm adsorption equations. This study investigated the solubility of Ni(II) and Cd(II) in 19 soils as a function of three extraction reagents (water, 0.01 M NaNO 3 , and 0.01 M CaCl 2 ), five solid/liquid ratios (5–400 g/L) and field condition extracted by Rhizon samplers. Thermodynamically based multi-surface models (MSMs) that included generic parameters were used to describe metal partitioning under the studied conditions. The results showed that Ni/Cd solubility depended on the soil type, extraction reagent, and solid/liquid ratio. Soil major background cations (especially Ca 2+ , Mg 2+ , Fe 3+ and Al 3+ ) had a significant effect on the model's prediction ability. The MSM was able to predict the extractable metal in 0.01 M CaCl 2 in various soils at different solid/liquid ratios when soil background cations were included in the calculation; without the background cations, the model was able to predict metal partitioning only at solid/liquid ratios of <100 g/L. In addition, the model failed to predict water-extracted and 0.01 M-NaNO 3 -extracted Ni/Cd if background cations were not included, but could reasonably do so if they were included. More importantly, after the background cations were included, MSMs relatively well predicted the Ni/Cd content in soil pore water under 80% field capacity conditions with water as the solution matrix. [ABSTRACT FROM AUTHOR]

A terrestrial biotic ligand model (t-BLM) was developed to predict nickel toxicity to wheat ( Triticum aestivum ) root elongation in hydroponic solutions. The competitive effects of five major cations (Ca 2 + , Mg 2 + , Na + , K + and H + ) on Ni toxicity were investigated and Mg 2 + was found to be a strong competitor, while H + showed less competing effect. Besides free Ni 2 + , the toxicity induced by the species NiHCO 3 + was non-neglect able at pH > 7 because NiHCO 3 + occupied a significant fraction of total Ni under such condition. Thus, a t-BLM including Ni 2 + , NiHCO 3 + , Mg 2 + , and H + could successfully predict the nickel toxicity to wheat root elongation and it performed better prediction than the conventional free ion activity model. In addition, the model was examined with two sets of independent experiments, which contained multiple cations and low-molecular-weight organic acids to mimic the rhizosphere condition. The developed t-BLM well predicted nickel toxicity in both experiments since it can account in both complexation and competition effects, suggesting its potential to be used in a complicated matrix like soil solution. This study provides direct evidence that the t-BLM is a reliable method for the risk assessment of nickel in terrestrial system. [ABSTRACT FROM AUTHOR]

This work sets out to investigate biological responses of Eisenia fetida to Cd, based on the bioavailable rather than total concentration of Cd, in soils. E. fetida was cultured for 14 d in three selected Chinese soils amended with 0.1–40 mg kg −1 Cd. Potentially bioavailable concentrations of Cd were measured in soil solution, in extractions using CaCl 2 and HAc solutions, and using the technique of diffusive gradients in thin-films (DGT). Antioxidant system responses in E. fetida to Cd were measured as biological endpoints. Biological responses were more highly correlated with Cd concentrations evaluated using bioavailable methods than with total concentrations. Cd concentration measured using DGT and CaCl 2 extraction provided the narrowest ranges of lowest observed effect concentration (LOEC) values based on biological responses, indicating the potential use of these measurements in management of soil quality and setting soil remediation standards. The LOEC values obtained from 15 field soils contaminated by Cd were similar to those from the three Cd-amended soils and suggested that DGT in particular can be a good tool to predict stress responses of E. fetida to Cd in soils. The study shows the potential of combining biological response and DGT measurements in risk assessment. [ABSTRACT FROM AUTHOR]

Due to its mobility and toxicity, chromate [Cr(VI)] partitioning in soils, especially in the vadose zone, is an important environmental concern. The aim of this study was to develop a mechanism-based multi-surface complexation model using published parameters to predict the soil/water partitioning of Cr(VI) in 12 soils (previously depleted of organic matter) from China. The retention of Cr(VI) in soils was attributed to two reactive oxide surfaces: goethite and hydrous ferric oxide (HFO); however, modeling results showed that the best prediction was obtained with goethite alone, whereas the addition of HFO resulted in an overestimation of adsorption in some soils. Cr(VI) adsorption onto goethite could be described using our previously proposed CD-MUSIC model. In the absence of a specific value for the soil-reactive surface area of goethite, a general value of 45.8 m 2 /g was used. The available phosphate in soils was identified as a strong competitor for Cr(VI) adsorption; thus, for soils with a low Fe/P ratio (<1) the effect of phosphate on Cr(VI) retention should not be neglected. The simple method presented herein can be applied to soils with a wide range of properties, pH values, and Cr(VI) loading concentrations. [ABSTRACT FROM AUTHOR]

The adsorption of glufosinate (GLU), a widely used herbicide similar to glyphosate (GLY), onto goethite was investigated as a function of the pH, ionic strength, background cations and anions, heavy metal ions and fulvic acids (FAs) by using batch adsorption experiments. In situ ATR-FTIR spectroscopy and density functional theory (DFT) calculations were carried out to characterize the molecular interactions between GLU and goethite surfaces. The macroscopic results indicated that an increasing pH exerted an adverse effect on GLU adsorption because of the electrostatic repulsion, and the adsorption was not sensitive to ionic strengths or background cation types, indicating that an inner-sphere surface complex was involved. GLU adsorption can be considerably depressed by PO 4 3 − , SO 4 2 − , and a high level of FA because of the competitive effect, while being enhanced by Cu 2 + with a maximum adsorption at approximately pH 5 because of the metal ion bridging effect. Other examined divalent metal cations (Cd 2 + , Zn 2 + , and Pb 2 + ) showed almost no effect on GLU adsorption, indicating weak interaction between them. ATR-FTIR spectra and the DFT calculations further proved that GLU was bonded to goethite surfaces through the formation of a monodentate mononuclear inner-sphere complex between the phosphinic moiety and surface Fe(III) centers under an acidic condition. The results showed that GLU had a similar adsorption mechanism to that of GLY onto goethite, but with a lower adsorption affinity, possibly exerting higher mobility and risk in soils. [ABSTRACT FROM AUTHOR]

Concerns regarding tetrabromobisphenol A (TBBPA), the most widely utilized brominated flame retardant in the world, are growing because of the wide application and endocrine-disrupting potential of this compound. To properly assess its environmental impacts, it is important to understand the mobility and fate of TBBPA in soil environments. In this study, the effects of soil components, dissolved organic carbon (DOC) and heavy metal cations on TBBPA adsorption onto two Chinese soils (red soil and black soil) were investigated using batch sorption experiments. The desorption behavior of TBBPA when the two soils are irrigated with eutrophicated river water was also investigated. The results showed that pH greatly affects the adsorptive behavior of TBBPA in soils. Iron oxide minerals and phyllosilicate minerals are both active surfaces for TBBPA sorption, in addition to soil organic matter (SOM). DOC (50 mg OC L − 1 ) exhibited a limited effect on TBBPA sorption only under neutral conditions. TBBPA sorption was only minimally affected by the heavy metals (Cu 2 + , Pb 2 + and Cd 2 + ) in the studied pH range. Eutrophicated river water significantly enhanced the desorption of TBBPA from red soil due to the change in soil solution pH. These findings indicate that mobility of TBBPA in soils is mainly associated with soil pH, organic matter and clay fractions: it will be retained by soils or sediments with high organic matter and clay fractions under acidic conditions but becomes mobile under alkaline conditions. [ABSTRACT FROM AUTHOR]

In this study, a charge distribution multisite surface complexation model (CD–MUSIC) for adsorption of chromate onto goethite was carefully developed. The adsorption of Cr(VI) on goethite was firstly investigated as a function of pH, ionic strength and Cr(VI) concentration. Results showed that an inner-sphere complexation mechanism was involved because the retention of Cr(VI) was little influenced by ionic strength. Then two surface species: a bidentate complex ( Fe 2 O 2 CrOOH) and a monodentate complex ( FeOCrO 3 −3/2 ), which is constrained by prior spectroscopic evidence were proposed to fit the macroscopic adsorption data. Modeling results showed that the bidentate complex was found to be the dominant species at low pH, whereas, with increasing pH, monodentate species became more pronounced. The model was then verified by prediction of competitive adsorption of chromate and phosphate at various ratios and ionic strengths. The model successfully predicted the inhibition of chromate with the presence of phosphate, suggesting phosphate has higher affinity to goethite surface than Cr(VI). Results showed that the model developed in this study for Cr(VI) onto goethite was applicable for various conditions. It is a useful supplement for the surface complexation model database for oxyanions onto goethite surfaces. [ABSTRACT FROM AUTHOR]

The coadsorption behavior of Cu(II) and ciprofloxacin (Cip), a zwitterionic fluoroquinolone (FQ) antibiotic, to goethite surfaces was characterized by means of batch adsorption experiments, attenuated total reflectance Fourier transform infrared (ATR–FTIR) spectroscopy, and extended X-ray absorption fine structure (EXAFS) spectroscopy. The collective quantitative and spectroscopic results indicate that Cip was adsorbed onto goethite surfaces through a tridentate complex involving the bidentate inner-sphere coordination of the deprotonated carboxylate group and H-bonding through the adjacent carbonyl group on the quinoline ring. In contrast, in the presence of Cu(II), Cip adsorption is enhanced around pH 6. Spectroscopic results showed that a goethite–Cu–Cip ternary surface complex is formed through the bidentate coordination of Cu(II) with the oxygen from the deprotonated carboxylate group and the adjacent carbonyl oxygen. A charge distribution (CD) surface complexation model constrained by spectroscopic observations was developed to describe macroscopic adsorption trends. The model well described the adsorption of Cip and Cu(II) under various conditions with one set of parameters. These findings will help quantitatively predict the adsorption behavior of Cip and Cu(II) onto ferric oxides. [ABSTRACT FROM AUTHOR]

The mobility of toxic metals in soils or sediments is of great concern to scientists and environmentalists since it directly affects the bioavailability of metals and their movement to surface and ground waters. In this study, a multi-surface soil speciation model for Cd (II) and Pb (II) was developed to predict the partition of metals on various soil solid components (e.g. soil organic matter (SOM), oxide mineral, and clay mineral). In previous study, the sorption of metal cations on SOM and oxide minerals has been evaluated by thermodynamically based surface complexation model. However, metal binding to soil clay fractions was normally treated in a simplistic manner: only cation exchange reactions were considered and exchange coefficient was assumed unity. In this study, the binding of metals onto clays was described by a two-site surface sorption model (a basal surface site and an edge site). The model was checked by predicting the adsorption behavior of Cd (II) and Pb (II) onto three selected Chinese soils as a function of pH and ionic strengths. Results showed that the proposed model more accurately predicted the metal adsorption on soils under studied condition, especially in low ionic strength condition, suggesting that adsorption of metals to soil clay fractions need to be considered more carefully when modeling the partition of trace elements in soils. The developed soil speciation model will be useful when evaluating the movement and bioavailability of toxic metals in soil environment. [ABSTRACT FROM AUTHOR]

Abstract: The adsorption of tetracycline (TC) on a Na-montmorillonite was studied as a function of five background electrolyte cations (Li+, Na+, K+, Mg2+ and Ca2+), one transitional metal cation (Cu2+) and humic acid (HA) over a pH range from 3 to 9 using batch experiments combined with XRD and FTIR measurement. Results showed that pH had great effect on the TC adsorption and acidic condition is more favored. Monovalent (Li+, Na+ and K+) and divalent (Mg2+, Ca2+ and Cu2+) cations showed very different effects on the TC adsorption onto montmorillonite. In the presence of monovalent cations, the adsorption edge curves were little affected by the types of cations. They presented a great decrease at pH<6, then an increase to a local maximum at about pH 8, followed by a gradual decrease (8Mg2+, which might be due to the capability of “bridge” effect of divalent cations. The difference of enhancing TC adsorption in the presence of Ca2+ and Mg2+ might be a result of different ionic radii and different interacting groups in TC molecular. XRD results showed that TC was intercalated into interlayers of montmorillonite since the interlayer expansion was observed. The band changes of amide carbonyl and amino groups in tricarbonyl methane group and the carbonyl group in phenolic deketone group in the FTIR spectra of TC equilibrated with montmorillonite confirmed that TC was adsorbed to the clay via cation exchange and surface complexation. It was also found that the effect of HA on the TC adsorption was pH-dependent and the presence of HA significantly reduced the mobility of TC in solution especially under acidic condition due to the complexation between cationic or zwitterionic TC species and the deprotonated sites on HA (mainly carboxylic groups) via electrostatic attraction. These results suggested that coexistence of divalent cations and HA would reduce TC''s mobility in soil environment, especially at acidic condition. [Copyright &y& Elsevier]

Abstract: Microcystins produced by cyanobacteria in the aquatic environment are a potential risk to aquatic plants. In the present study, the uptake of microcystin-LR (MC-LR) and related physiological and biochemical effects on Vallisneria natans (Lour.) Hara were investigated at concentrations of 0.1–25.0μgL−1. Results showed that O2 − intensity was significantly induced at 1.0μgL−1 and reached a maximum level at 5.0μgL−1. Superoxide dismutase (SOD) and peroxidase (POD) were induced with increasing MC-LR concentrations as an antioxidant response. Catalase (CAT) was significantly induced while GSH/GSSG (reduced/oxidized glutathione) ratio was significantly reduced at 0.1μgL−1. The induction of glutathione S-transferase (GST) and inhibition of GSH revealed that GSH was involved in the detoxification of MC-LR in plants. Oxidative damage was evidenced by the significant increase of malondialdehyde content at 1.0μgL−1. A pigment pattern change and a series of significant ultrastructural alterations were also observed due to MC-LR exposure. The lowest non-effect concentration of MC-LR for V. natans at the subcellular and molecular level is around 0.5μgL−1. These results imply that even at relatively low MC-LR concentrations the aquatic plants may still suffer a negative ecological impact. [Copyright &y& Elsevier]

Abstract: The adsorption of five toxic metallic cations, Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II), onto montmorillonite was investigated as a function of pH and ionic strength and a two-site surface complexation model was used to predict the adsorption data. The results showed that in the lower pH range, 3∼6 for Cd, Cu, Ni and Zn, and 3∼4.5 for Pb, the adsorption was greatly affected by ionic strength, while in the higher pH range, the adsorption was not. In the lower pH range, the metallic cations were mainly bound through the formation of outer-sphere surface on the permanently charged basal surface sites (≡X−), while in the higher pH range the adsorption occurred mainly on the variably charged edge sites (≡SOH) through the formation of inner-sphere surface complexes. Acid-base surface constants and metal binding constants for the two sites were optimized using FITEQL. The adsorption affinity of the five metallic cations to the permanently charged sites of montmorillonite was Pb>Cu>Ni≈Zn≈Cd, while that to the variable charged sites was Pb≫Cu>Zn>Cd>Ni. [Copyright &y& Elsevier]

Abstract: Illite samples from Fithian, IL were purified and saturated with Na+ ions. The acid–base surface chemistry of the Na-saturated illite was studied by potentiometric titration experiments with 0.1, 0.01, and 0.001 M NaNO3 solutions as the background electrolyte. Results showed that the titration curves obtained at different ionic strengths did not intersect in the studied pH range. The adsorption of Cd(II), Cu(II), Ni(II), Pb(II), and Zn(II) onto illite was investigated as a function of pH and ionic strength by batch adsorption experiments. Two distinct mechanisms of metal adsorption were found from the experimental results: nonspecific ion-exchange reactions at lower pH values on the basal surfaces and ‘frayed edges’ and specific adsorption at higher pH values on the mineral edges. Ionic strength had a greater effect on the ion-exchange reactions. The binding constants for the five heavy metals onto illite were determined using the least-square fitting computer program FITEQL. Linear free energy relationships were found between the surface binding constants and the first hydrolysis constants of the metals. [Copyright &y& Elsevier]

Studies the effects of humic acid on speciation and bioavailability to wheat of rare earth elements in soil. Humic acids; Rare earth elements; Bioavailability.

[Display omitted] [ABSTRACT FROM AUTHOR]

Current models for inorganic ion transport in porous media describe the adsorption–desorption processes mostly based on empirical adsorption isotherms or simple thermodynamic mechanisms, often overlooking the adsorption kinetics. This study introduces a novel unified reactive solute transport model framework that incorporates well-established surface complexation models to describe the adsorption–desorption of ions in the transport process and takes into full consideration the non-equilibrium adsorption, enabling the use of the same set of thermodynamic-kinetic parameters to accurately describe ion transport under different chemical conditions. To evaluate the constructed model, Cr(VI), P(V), and As(V) column transport experiments were carried out using goethite-coated sand as the porous medium. Kinetic constants derived from single-ion transport experiments accurately predicted the cotransport behaviors of Cr(VI), P(V), and As(V) under various flow chemistry conditions, especially the overshooting phenomena of Cr(VI) under P(V) and As(V) competition. The model framework can be easily incorporated into solute transport models with various surface complexation reactions to predict the fate and transport of ions under complexed chemical conditions without extensive parameterization, and thus is a useful complement to the current reactive transport model. [ABSTRACT FROM AUTHOR]

Abstract: In metal toxicity model studies of soil–plant systems, hydroponic culture is often employed to simulate soil conditions, but the validity of this approach has not been examined. The present study evaluated Ni toxicity to wheat root elongation using models developed in hydroponic and sand cultures and then compared the results with those obtained from real soils. Three mechanism toxicity models were examined: the free ion activity model, the biotic ligand model (BLM), and the Gouy‐Chapman‐Stern model. After being developed in hydroponic and sand culture bioassays, the models were validated with 18 soils from across China. The results showed that more accurate predictions were obtained with sand rather than hydroponic bioassays. Dissolved organic matter exerted only a limited effect on Ni toxicity, whereas an important role was found for osmotic effects. Of the 3 models, the sand‐based BLM best predicted Ni toxicity to wheat root elongation (root‐mean‐square error = 16.2% and R2 = 0.79) and was as good as the BLM estimated directly from soils. The present study shows that sand is a better matrix than solution for root elongation bioassays of Ni toxicity and that osmotic effects must be taken into account in evaluating soil conditions. Environ Toxicol Chem 2018;37:1349–1358. © 2018 SETAC [ABSTRACT FROM AUTHOR]

Birnessite minerals help control the fate of Zn in surface environments and readily fractionate Zn isotopes through adsorption reactions, yet little is known about the role played by various reactive sites in stable isotopic fractionation. Here we present the Zn isotope fractionation data cause by adsorption on birnessite under different reaction times, pH values, and Zn concentrations. We observe that isotopic equilibrium of Zn is attained after ∼120 h of reaction time at pH 6. At pH 3–5 and Zn concentrations of 0.05–0.3 mM, the isotopic fractionation (Δ66Zn adsorbed-aqueous) is around −0.46 ± 0.04‰, and gradually increases to −0.09 ± 0.05‰ at pH 6–8 and Zn concentrations of 0.2 mM. The change in Zn isotopic compositions as a function of pH and Zn concentration is well described using the surface complexation model, where two binding sites are involved: external edge sites and interlayer vacancies. According to this model, two different isotopic fractionation factors of Zn are calculated: Δ66Zn adsorbed-aqueous = −0.46 ± 0.04‰ for adsorption on vacancy sites and Δ66Zn adsorbed-aqueous = 0.52 ± 0.04‰ for binding to edge sites. Extended X-ray absorption fine structure spectroscopy (EXAFS) demonstrates that Zn forms triple-corner-sharing (TCS) octahedral complex on birnessite vacancies at pH 3 and Zn concentrations of 0.05–0.2 mM, where Zn is coordinated on one side to three oxygen atoms of the Mn vacancy (∼2.03 Å) and to three water molecules on the other side (∼2.15 Å), suggesting the formation of distorted Zn O octahedra (average bond length: ∼2.09 Å). At pH 6 and 8, double-corner-sharing (DCS) complexes on layer edges formed in addition to the TCS octahedral complex on vacancies. Density functional theory (DFT) optimisations suggest that DCS Zn complex exist in tetrahedral coordination. Based on EXAFS spectroscopy, DFT optimisations and surface complexation modeling, the distinct isotopic fractionation of Zn is related to the differences in Zn local structure at different reactive sites of birnessite. Our results provide a molecular-scale understanding of Zn isotopic fractionation in natural birnessite-containing settings, as well as new insights into predicting the links between adsorption and fractionation of other similar metals. [ABSTRACT FROM AUTHOR]

Arsenic pollution poses severe threat to human health, therefore dealing with the problem of arsenic contamination in water bodies is extremely important. The adsorption behaviors of different arsenic species, such as arsenate (As(V)), p-arsanilic acid (p-ASA), roxarsone (ROX), dimethylarsenate (DMA) from water using mesoporous bimetal oxide magnetic manganese ferrite nanoparticles (MnFe 2 O 4 ) have been detailedly investigated. The adsorbent was synthesized via a facile co-precipitation approach and recovered conveniently owing to its strong magnetic properties. The obtained MnFe 2 O 4 with large surface area and abundant hydroxyly functional groups exhibited excellent adsorption performance for As(V) and p-ASA, in contrast to ROX and DMA with the maximum adsorption capacities of As(V), p-ASA, ROX and DMA of 68.25 mg g −1 , 59.45 mg g −1 , 51.49 mg g −1 , and 35.77 mg g −1 , respectively. The Langmuir model and the pseudo-second-order kinetic model correlated satisfactorily with the adsorption thermodynamics and kinetics, and thermodynamic parameters depicted the spontaneous endothermic nature for the adsorption of different arsenic species. The adsorption mechanism of different arsenic species onto MnFe 2 O 4 nanoparticles at various pH values could be explained by surface complexation and molecular structural variations. Attenuated Total internal Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) further proved that arsenic species were bonded to the surface of MnFe 2 O 4 through the formation of an inner-sphere complex between the arsenic acid moiety and surface metal centers. The results would help to know the interaction of arsenic species with iron-manganese minerals and the mobility of arsenic species in natural environments. [ABSTRACT FROM AUTHOR]

Soil toxicological tests are commonly performed using Eisenia fetida as the standard earthworm species, but it is tolerant to a wide range of pollutants. Therefore, the inclusion of susceptible species is crucial for the accurate estimation of soil contamination. In this study, we examined the sensitivity to soil cadmium (Cd) of anecic Metaphire guillelmi and epigeic E. fetida by measuring multiple indexes of oxidative stress. Using subcellular partitioning analysis, we further elucidated the inherent mechanism underlying the species-specific sensitivity of the two earthworm species. Among the battery of biochemical indexes, reactive oxygen species and protein carbonyl groups served as sensitive biomarkers. According to their respective response thresholds, M. guillelmi was more sensitive than E. fetida and they differed in their dose-response relationships. In E. fetida , the activities of three antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST), exhibited a hormesis-like U-shaped dose-response relationship, while in M. guillelmi SOD, glutathione peroxidase (an analogue of CAT) and GST showed an inverted U-shaped relationship. The concentrations of Cd in the subcellular fractions and whole body of the earthworms well fit ( R 2 > 0.9) a saturation model versus bioavailable Cd concentrations determined by the diffusive gradients in thin films technique. Despite the lower accumulation capacity of M. guillelmi , the Cd-binding capacity ( C max ) of its subcellular heat-stable protein fraction, the so-called biologically detoxified metal pool, was 2.7 times lower than that of E. fetida , whereas the Cd binding affinity (log K ) of its heat-denatured protein fraction, i.e. the metal-sensitive fraction, was 3.0 times higher, which accounted for the high susceptibility of M. guillelmi to soil Cd. Our results suggest that because of their sensitivity, as exemplified by M. guillelmi , native earthworm species should be taken into account in soil risk assessments to avoid underestimation of the toxicity of various pollutants. [ABSTRACT FROM AUTHOR]

Hexavalent chromium, Cr(VI), is a ubiquitous toxic metal that can be reduced to Cr(III) by nano-zero-valent iron (nZVI). Finding out effects of continuous rainfall leaching on the Cr(VI) release and availability remains a problem, needing to be addressed. Whether the Cr(VI) reduction by nZVI and continuous rainfall leaching lead to localized heterogeneity in soil is unclear. Therefore, two in situ high-resolution (HR) techniques of the diffusive gradients in thin-films (DGT) and planar optode were combined with ex situ sampling experiments here. Results demonstrate that nZVI decreased Cr(VI) leaching by 5.60–8.50 % compared to control soils. DGT-measured concentrations of Cr(VI), C DGT -Cr(VI), ranged from 7.31 to 19.4 μg L-1 in the control soils, increasing with depth while C DGT -Cr(VI) in nZVI-treated soils (2.41–6.18 μg L-1) decreased or remained stable with depth. However, simulated acid-rain leaching increases C DGT -Cr(VI) by 1.61-fold in nZVI-treated soils, negatively affecting the remediation. DGT measurements in bulk soils using disc devices are better at capturing the change of Cr(VI) availability at different conditions, whereas 2D-HR DGT mappings did not characterize significant mobilization of Cr(VI) at the micro-scale. These findings emphasize the importance of monitoring Cr(VI) release and availability in remediated soil under acid-rain leaching conditions for effective environment management. [Display omitted] • Investigate soil dynamic under acid rain leaching using an in situ deployment system. • Significant decreases in Cr(VI) availability observed in nZVI-treated soils. • Long-term acid rain leaching increased the Cr(VI) resupply potential in soils. • 2D distribution of Cr(VI) availability in leaching soil columns was revealed. • No significant hotspots of labile Cr(VI) in nZVI-treated soils after leaching. [ABSTRACT FROM AUTHOR]

Abstract: The surface adsorption behavior of tetracycline (TC), a zwitterionic antibiotic, to goethite was investigated as a function of pH, ionic strength and TC concentration using batch adsorption experiments and structural information was derived from attenuated total reflectance Fourier transform infrared spectrum observations. The spectroscopic results suggested that the tricarbonylamide group and the phenolic diketone group of the TC molecule were involved in interacting with the goethite surface depending on the pH level. A charge distribution surface complexation model was developed to describe the macroscopic adsorption trends. Two inner-sphere surface complexation species could successfully describe observed adsorption trends: under acidic condition TC may interact with the surface of goethite, forming a monodentate complex through the tricarbonylamide group, while under alkaline condition forming a more stable bidentate complex via the tricarbonylamide and phenolic diketone groups. The model could well predict the adsorption behavior of TC under a relatively wide range of pH, ionic strength and surface coverage. However, since the model did not fully consider the molecular size of TC, the model might overestimate the adsorption when TC surface coverage is higher than 1.42μmolm−2. [Copyright &y& Elsevier]

[Display omitted] • N and S co-doped mesoporous carbons (NS-MCs) were used for the activation of peracetic acid (PAA). • N and S co-doping greatly enhanced the activation performance of MC. • A nonradical mechanism dominated by singlet oxygen was proved in the NS-MC/PAA system. • NS-MC exhibited excellent reusability for PAA activation. Metal-free peracetic acid (PAA) activators are urgently required due to their low toxicity. Heteroatom doping is beneficial to improve the catalytic performance of carbon materials, but the activation performance of doped carbon materials on PAA and the underlying mechanism have not been reported. Herein, nitrogen and sulfur co-doped mesoporous carbons (NS-MC-x, with x representing the mass ratio of thiourea:mesoporous carbon) were fabricated and used as efficient PAA activators for 4-chlorophenol (4-CP) degradation. The NS-MC-1.0/PAA system can remove > 95 % of 4-CP within 10 min, far more than the MC/PAA system. Co-existing anions show no effect on the degradation of 4-CP, whereas humic acid has a certain degree of inhibition. Singlet oxygen (1O 2) primarily drives the degradation of 4-CP, with a secondary contribution from a direct electron transfer process mediated by reactive surface complexes, while the contribution of radicals is minimal. In addition, NS-MC-1.0 exhibits excellent reusability for PAA activation, which is conductive to its practical application. This study facilitates further research on metal-free catalysts for PAA activation and offers fresh perspectives on the utilization of PAA in degrading emerging pollutants. [ABSTRACT FROM AUTHOR]

While antimony (Sb) and arsenic (As) co-contamination in subsurface soil systems due to the legacy of Sb smelting wastes has been documented, the role of inherent heterogeneity on pollutant migration is largely overlooked. Herein this study investigated Sb and As migration in a slag impacted, vertically stratified subsurface at an abandoned Sb smelter. A 2-dimensional flume was assembled as a lab-scale analogue of the site and subject to rainfall and stop-rain events. Reactive transport modeling was then performed by matching the experimental observations to verify the key factors and processes controlling pollutant migration. Results showed that rainfall caused Sb and As release from the shallow slag layer and promoted their downward movement. Nevertheless, the less permeable deeper layers limited physical flow and transport, which led to Sb and As accumulation at the interface. The re-adsorption of Sb and As onto iron oxides in the deeper, more acidic layers further retarded their migration. Because of the large difference between Sb and As concentrations, Sb re-adsorption was much less effective, which led to higher mobility. Our findings overall highlight the necessity of understanding the degree and impacts of physicochemical heterogeneity for risk exposure assessment and remediation of abandoned Sb smelting sites. [Display omitted] • Migration of Sb and As in a smelting impacted, stratified subsurface was studied. • The heterogeneity in permeability caused Sb and As accumulation at the interface. • Sb and As re-adsorption in the deeper, more acidic layers retarded their migration. • The Sb mobility was high due to high Sb solid content and ineffective re-adsorption. [ABSTRACT FROM AUTHOR]

Abstract: The regional geochemical survey of soils in Jiangsu Province is an important part of a larger agro-geological survey program in China. This paper presents chemical data from soils sampled at two depths; top-soils from a 0–20 cm depth and sub-soils from a 150–200 cm depth. Results for eleven of the fifty four elements measured are presented for approximately 103,000 top-soils and 26,000 sub-soils. The discussion includes the fertility status and the distribution of soil pH, phosphorous and total organic carbon; and a soil contaminant assessment of eight potentially toxic elements (As, Cd, Hg, Pb, Ni, Cr, Cu and Zn). For a smaller sub-sample from the Nanjing area (3397 top-soils and 834 sub-soils), elemental enrichment factors for twenty eight elements were calculated. From the study, the following conclusions can be made — 1) 50% of the land shows fertility deficiencies as estimated by N, P, K contents and pH; 2) the toxic element contents in about 30% of the land were assessed to be above their natural background concentrations, with over 10% of the land being classified as contaminated; 3) top-soil contamination from toxic elements occurs mainly in urban environments with significant compositional differences between top-soils and sub-soils for many elements, particularly Hg, Cd, Pb, S and Se; 4) the data from regional geochemical surveys of soils can play an important role in studying changes in the ecological environment. [Copyright &y& Elsevier]

Polyethylene (PE) mulch films are an important source of microplastics (MPs) in agricultural soils, which may further affect the bioavailability of coexisting pollutants. In this study, white (WM), black (BM), and silver-black (SM) PE mulch films were aged on the soil surface and under soil burial to simulate the two exposure patterns of abandoned mulch films in the field. Results indicated that the soil-surface exposure induced more pronounced aging characteristics, and WM seemed the most susceptible. Serious surface deterioration by aging led to a drastic decrease in the tensile properties of the films, suggesting the tendency to fragment. Oxygen-containing functional groups were generated on the film surfaces, with oxygen/carbon ratios increasing by up to 29 times, which contributed to the prominent increase in Pb adsorption on the film-derived MPs. Additionally, the film surface became more hydrophobic when exposed to the soil surface but more hydrophilic in the soil-burial exposure, which was in agreement with the change in triclosan adsorption, i.e., promotion and suppression, respectively. Aging generally decreased the desorption potential of the adsorbed pollutants in simulated gastrointestinal solutions due to increased interactions. By comparison, exposure patterns were revealed to be the critical factor for these changes, regardless of film types. [Display omitted] • White polyethylene (PE) mulch film was the most susceptible to aging. • Soil-surface aging produced greater deterioration in PE films than soil-burial aging. • Soil-surface aging increased triclosan and Pb adsorption capacities of microplastics. • Aging decreased desorption rates of chemicals in simulated gastrointestinal fluids. • Exposure patterns played a central role in pollutant bioavailability. [ABSTRACT FROM AUTHOR]

Nanomaterial application in agriculture offers novel solutions for soil arsenic (As) pollution control, yet safety along the food chain is of concern. We comprehensively assessed CeO 2 nanoparticles (NPs) foliar application effects on As uptake by pakchoi and their presence in the pakchoi-snail food chain. CeO 2 NPs reduced As transfer from pakchoi roots to shoots by 37.9%, lowered As in snail foot by 39%, and halved human As exposure risk. The NPs alleviated pakchoi shoot As toxicity by regulating antioxidants, enhancing water use efficiency, and photosynthesis. CeO 2 +As treatment raised GSH/GSSG ratios by 38.92%− 167.54%, leading to an increased AsIII/AsV ratio and inorganic As detoxification compared to As alone. Metabolomics revealed CeO 2 's rapid As response via phosphatidylinositol signaling. The enzyme-like activity of CeO 2 NPs may drive these effects. While CeO 2 foliar application accumulated Ce on pakchoi leaves, > 99% of Ce was excreted following snail consumption. Ce transfer from pakchoi leaves to snail foot was minimal (trophic transfer factor ∼0.00007) due to limited bioavailability. The target hazard quotient of Ce in pakchoi shoot (1.21 ± 0.18) and snails (0.0016 ± 0.0004) indicated low exposure risk, suggesting a 'risk filter' effect for CeO 2. Our results contribute to the safe and sustainable application of CeO 2 NPs in the future implication. [Display omitted] • Foliar spraying CeO 2 NPs inhibited As translocation from roots to shoots. • CeO 2 NPs enhanced water use efficiency, antioxidation, and signal transduction. • Most CeO 2 sprayed in pakchoi was excreted from snail via feces. • The risk of Ce to human via consumption of pakchoi and snails was negligible. [ABSTRACT FROM AUTHOR]

Pillararene polymers have been widely used as excellent adsorbents for water treatment, but pillararene polymers with ultra-high specific surface area and versatility are still rarely reported. Herein, a quaternary ammonium salt modified pillar [5] arene polymer, QPBP [5], with specific surface area of 1844 m2 g−1 was successfully synthesized. Since QPBP [5] has abundant different adsorption sites, it exhibits excellent performance for the simultaneously removal of organic pollutants with different charges from water. The selected three model pollutants, Rhodamine B (RhB, positively charged), Sulfamethazine (SMT, electrically neutral) and Fulvic acid (FA, negatively charged), could be rapidly and efficiently removed from water by QPBP [5] within 10 min, which are much faster than them by most of the reported adsorbents. RhB and SMT are mainly adsorbed through hydrophobic interactions with the QPBP [5] surface, while FA is mainly removed through ion exchange. In addition, QPBP [5] also showed excellent reusability and adsorption performance for the environmentally relevant concentration of pollutants. Furthermore, the quaternary ammonium groups on QPBP [5] makes it a solid disinfectant with excellent antibacterial properties. In conclusion, QPBP [5] is a promising multifunctional adsorbent for the treatment of complex pollutants in water. [Display omitted] • Quaternary ammonium salt modified pillar [5] arene polymer was synthesized. • The polymer has a specific surface area up to 1844 m2 g−1. • The polymer can efficiently remove contaminants of different charge types. • The polymer showed excellent disinfection properties. [ABSTRACT FROM AUTHOR]

The prediction of metal bioavailability in soils is critical to metal risk assessments and the amount of dissolved metal in soils is a key factor determining bioavailability. Because the recently developed geochemical multi-surface models (MSMs) offer a promising tool for the determination of metal partitioning in soils, in this study, a MSM based on generic parameters was used to assess the bioavailability of Cd in wheat ( Triticum aestivum L.) growing in 12 soils with a wide range of properties. The amount of MSM-calculated dissolved Cd correlated strongly with the amount of Cd uptake by wheat ( R 2 = 0.873 for roots and R 2 = 0.837 for shoots), and the model's performance was better than that of chemical extraction methods (0.01 M CaCl 2 , 0.43 M HNO 3 and soil total Cd). The reactive fraction of soil organic matter, the soil/solution ratio, and the inclusion/exclusion of background cations influenced the calculation results. The best calculation condition was optimized. The application of the MSM was also examined in 84 wheat-soil samples from the field. The amount of Cd in wheat seeds had a stronger correlation with the amount of MSM-predicted Cd than with the amount of Cd obtained using chemical extraction methods. Our results suggested that MSM-calculated Cd is an effective indicator of the bioavailability of Cd in soils and demonstrated the utility of the method as a tool to assess the risk of Cd contamination in soils. [ABSTRACT FROM AUTHOR]

Rapid and accurate prediction of metal bioaccumulation in crops are important for assessing metal environmental risks. We aimed to incorporate machine learning modeling methods to predict heavy metal contents in rice crops and identify influencing factors. We conducted a field study in Jiangsu province, China, collecting 2123 pairs of soil-rice samples in a uniform measurement and using 10 machine learning algorithms to predict the uptake of Cd, Hg, As, and Pb in rice grain. The Extremely Randomized Tree model exhibited the best performance for rice-Cd and rice-Hg (Cd: R 2 = 0.824; Hg: R 2 = 0.626), while the Random Forest model performed best for As and Pb (As: R 2 = 0.389; Pb: R 2 = 0.325). The feature importance analysis showed that soil-Cd and pH had the highest impact on rice-Cd risk, which is in line with previous studies; while temperature and soil organic carbon were more important to rice-Hg than soil-Hg. Then, based on another set of 1867 uniformly distributed paddy soil samples in Jiangsu province, the Cd and Hg risks of soil and rice were visualized using the established models. Mapping result revealed an inconsistent pattern of hotspot distribution between soil-Hg and rice-Hg, i.e., a higher rice-Hg risk in the northern area, while higher soil-Hg in south. Our findings highlight the importance of temperature on Hg bioaccumulation risk to crops, which has often been overlooked in previous risk assessment processes. [Display omitted] • Soil metal contents and properties were most important factors to rice uptake. • Temperature and precipitation negatively affected rice-Hg and rice-Pb, respectively. • Root uptake might be main pathway for Cd, while foliar uptake for Hg and Pb. • Broader features should be considered in predicting metal bioaccumulation. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) have recently become an emerging environmental concern. Nevertheless, limited information is known about the adsorption of MPs for organic contaminants under combined heavy metals pollution, with an emphasis on the role of complexation. Thus, this study aims to comprehensively compare and investigate the adsorption performance of antibiotic tetracycline (TC) and ciprofloxacin (CIP) on two polar MPs (polyamide (PA) and polyvinyl chloride (PVC)) affected by Cu(II) and Cd(II) with contrasting complexation abilities. Batch adsorption experiments were used in combination with speciation calculation, zeta potential determination, FTIR spectroscopy characterization and investigation of the affinity of MPs for heavy metals. Results showed that the sorption kinetics and isotherms of TC and CIP on PA and PVC could be well fitted to pseudo-second-order and Langmuir models, respectively, both in the absence and presence of Cu and Cd, suggesting that multiple interactions and monolayer adsorption played an important role in the adsorption process. The presence of Cu substantially improved TC and CIP adsorption and obviously changed the pH dependence of their adsorption onto both MPs, which may result from the Cu-induced strong complexation with TC and CIP. The presence of Cd slightly enhanced TC adsorption on both MPs while reduced CIP adsorption especially on PVC, which may be ascribed to the Cd-induced cationic bridging effects in TC adsorption and the competitive adsorption of Cd in CIP adsorption. Therefore, the heavy metal-mediated complexation effects may play a dominant role in antibiotic adsorption by MPs only in the presence of heavy metals with strong complexation ability while the adsorption performance in the presence of heavy metals with negligible complexation capacity may be influenced by effects other than complexation. This study helps further understand the heavy metal-mediated adsorption behavior of organic contaminants on polar MPs and the role of complexation reactions therein. • Sorption of antibiotics on two polar microplastics mediated by Cu and Cd was studied. • Detailed calculation of chemical species in various composite systems was involved. • Cu substantially enhanced antibiotic sorption due to dominant complexation mechanism. • Cd improved or inhibited sorption due to cationic bridging or competitive sorption. • Role of complexation in sorption basically relied on complexation ability of metals. [ABSTRACT FROM AUTHOR]

The application of terrestrial toxicity models to real soil environments is a challenge due to the heterogeneity of soil. We presented here a novel bioassay-geochem-model coupling approach to predict the bioaccumulation and toxicity of a metal mixture in different soils. Equations describing dose-accumulation and dose-toxicity relationships of Cd-Ni mixtures to wheat root elongation were generated using a standard sand culture bioassay. A geochemical multi-surface speciation model (MSM) with default parameters was employed to predicted the dissolved metal contents C dis of three soils collected in China with different properties. Several toxicity models (TU/CAM + FIAM/BLM/GCSM) were screened to identify the one yielding the most accurate predictions. The results showed that metal bioaccumulation was better predicted by the MSM- C dis integrated with the dose-accumulation equation (RMSE < 0.58) than by the detection of metal contents in soil porewater (RMSE < 0.74). The MSM predicted metal ion activities combined with the BLM+CAM model successfully predicted Cd-Ni toxicity in all three soils (RMSE = 20.7%), but the deviation was slightly larger than that obtained in measurements of metals in soil porewater (RMSE =17.2%). Our study demonstrates that the MSM coupled with the dose-accumulation and dose-toxicity equations derived from sand bioassays offers a promising approach in risk assessments of mixed metals in actual soils while avoiding tedious soil bioassays, which will greatly improve the practical application value of terrestrial toxic models. [Display omitted] • A novel bioassay-MSMs coupling approach was proposed for soil-plant systems. • The model's toxicity parameters are derived from sand culture bioassays. • Amounts of dissolved metal in soils are predicted using a geochemical MSM. • The combination of sand bioassays and MSM enables toxicity predictions in soils. • This approach was successfully verified by predicting Cd-Ni toxicity in three soils. [ABSTRACT FROM AUTHOR]

Intense industrialization has led to the increasing leaching risk of metals into groundwater at heavily polluted industrial sites. However, metal dissolution in polluted industrial soils has been neither fully investigated nor quantified before. In this study, the dissolution of Zn, Ni, and Cu in soil from a heavily contaminated industrial site during a flooding-drainage period was investigated by sequential extraction, geochemical modelling, and X-ray absorption near edge structure spectroscopy. The results showed a steady decrease in metal solubility during both reduction and oxidation stages. During reduction, with limited decrease in Eh (>100 mV), formation of carbonate precipitates rather than sulfide precipitates and adsorption on soil solids was responsible for Zn and Ni dissolution, whereas bound to soil organic matter (SOM) and iron oxides dominated Cu dissolution, due to its lower concentration and higher affinity to SOM and iron oxides compared to Zn and Ni. During oxidation, the acidity caused by ferrous oxidation was buffered by calcite dissolution, while metal precipitation ceased and adsorption on soil surface controlled metal solubility. The metal solubility and speciation during the flooding-drainage process were quantitatively predicted by geochemical model. The findings demonstrate that due to high metal concentrations and weak microbial effect in the industrial soil, metal release was largely regulated by abiotic reactions rather than biotic reactions, which is somehow different from that of the wetland or rice field soils. [Display omitted] • Metal dissolution decreased during flooding and drainage. • Metal dissolution was mainly regulated by abiotic reactions. • Precipitate formation led to Zn and Ni stabilization under reducing condition. • Increasing adsorption was responsible for Cu stabilization. • Metal dissolution was well predicted by a geochemical speciation model. [ABSTRACT FROM AUTHOR]

With large specific surface area, abundant adsorption sites, flexible pore structure, and good water stability, Materials of Institute Lavoisier frameworks (MILs) have attracted increasing attention as effective environmental adsorbents. This review systematically analyzes and recapitulates recent progress in the synthesis and application of MIL-based adsorbents for the removal of aqueous heavy metal ions. Commonly used solvothermal, microwave, electrochemical, ultrasonic, and mechanochemical syntheses of MILs are first summarized and compared. Instead of focusing on adsorption process parameters, adsorption performances and governing mechanisms of virgin MILs, functional MILs, MIL-based composites, and carbonized MILs to representative metal(loid) ions (chromium, arsenic, lead, cadmium, and mercury) in water under various conditions are then systematically reviewed and discussed. In the end, this work also outlines prospects and future directions to promote the applications of MILs in treating heavy metal contaminated water. [Display omitted] • Advantages and limitations of synthesis methods of MILs are summarized and compared. • Adsorption performances of MILs to aqueous metal(loid) ions are reviewed and compared. • Adsorption mechanisms of MILs to aqueous metal(loid) ions are analyzed and recapitulated. • Future perspectives of MILs in wastewater treatment are proposed. [ABSTRACT FROM AUTHOR]

Predicting the dynamic behavior of coexisting ions on mineral interface is essential to understanding their lability in soil matrix, but a mechanical kinetic model for predicting competitive adsorption is lacking. In this study, the thermodynamic and kinetic adsorption behaviors of Ni(II), Co(II), Cr(VI), and P(V) on goethite under various condition were investigated by batch and stirred-flow experiments, respectively. The equilibrium model CD-MUSIC was developed to describe their equilibrium behavior, followed by the development of a multi-rate kinetic model constrained by the equilibrium model to describe their kinetic behavior. Ni(II) and Co(II) exhibit similar adsorption affinities, while the adsorption of P(V) was stronger and faster than that of Cr(VI). The two surface species of Cr(VI) and P(V) differed in dynamic features, a finding confirmed by in-situ ATR-FTIR spectroscopy. The kinetic model was successfully used to predict the binary competitive adsorption of Ni(II)-Co(II) and Cr(VI)-P(V), and especially the overshooting of Cr(VI) induced by P(V). Our results showed that an integrated thermodynamic-kinetic model obtained from a single-ion experiment can be extended to describe complex multi-ion interactions, indicating the robustness and scalability of the model's parameters. This approach can be used to construct more comprehensive equilibrium and dynamic models of the actual soil environment. [Display omitted] • The adsorption of Ni(II), Co(II), Cr(VI), and P(V) on goethite was investigated. • An integrated thermodynamic-kinetic model was developed. • The model is suitable for various pH, loading concentrations and ionic strength. • The binary competitive adsorption was predicted by model derived from single-ion. [ABSTRACT FROM AUTHOR]

Abstract: Adsorption of tetracycline, one of the most widely used antibiotics, onto goethite was studied as a function of pH, metal cations, and humic acid (HA) over a pH range 3–10. Five background electrolyte cations (Li+, Na+, K+, Ca2+, and Mg2+) with a concentration of 0.01M showed little effect on the tetracycline adsorption at the studied pH range. While the divalent heavy metal cation, Cu2+, could significantly enhance the adsorption and higher concentration of Cu2+, stronger adsorption was found. The results indicated that different adsorption mechanisms might be involved for the two types of cations. Background electrolyte cations hardly interfere with the interaction between tetracycline and goethite surfaces because they only form weak outer-sphere surface complexes. On the contrary, Cu2+ could enhance the adsorption via acting as a bridge ion to form goethite–Cu2+–tetracycline surface complex because Cu2+ could form strong and specific inner-sphere surface complexes. HA showed different effect on the tetracycline sorption under different pH condition. The presence of HA increased tetracycline sorption dramatically under acidic condition. Results indicated that heavy metal cations and soil organic matters have great effects on the tetracycline mobility in the soil environment and eventually affect its exposure concentration and toxicity to organisms. [Copyright &y& Elsevier]

Abstract: A microwave assisted zero-valent iron oxidation process was studied in order to investigate the synergetic effects of MW irradiation on Fe/EDTA system (Fe/EDTA/MW) treated 4-nitrophenol (4-NP) from aqueous solution. The results indicated that the thermal effect of microwave improved the removal effect of 4-NP and TOC through raising the temperature of the system, as well as the non-thermal effect generated by the interaction between the microwave and the Fe resulting in an increase in the hydrophobic character of Fe surface. During the degradation of 4-NP in Fe/EDTA/MW system, the optimum value for MW power, Fe, EDTA dosage was 400W, 2g and 0.4mM, respectively. The possible pathway for degrading the 4-NP was proposed based on GC/MS and HPLC analysis of the degradation intermediates. The concentration change course of the main bio-refractory by-products, the aminophenol formed in the degradation of 4-NP suggested a more efficient degradation and mineralization in Fe/EDTA/MW system. Finally, BOD5/CODCr of the solution increased from 0.237 to 0.635 after reaction for 18min, indicating that the biodegradability of wastewater was greatly improved by Fe/EDTA/MW system and would benefit to further treatment by biochemical methods. [Copyright &y& Elsevier]

Abstract: Phosphine is a natural gaseous compound in the phosphorus biogeochemical cycle. This paper studies the spatial and temporal distributions of matrix-bound phosphine (MBP) and gaseous phosphine in the offshore area of the Southwest Yellow Sea, East Asia. The results show that MBP concentrations in marine surface sediments range from 0.69±0.06ng/kg (dry) to 179±29ng/kg (dry). Higher seasonal MBP concentrations in sediments are found in fall than in spring or winter in most sites. High MBP contents are observed in two fish-breeding areas. MBP concentrations decrease with distance to the coast, except in the southeast of the sampling area. MBP levels in marine sediments are found to be higher than those at several other places: freshwater sediments and soil, except eutrophic lakes. Gaseous phosphine contents in fall range from 0.14±0.00ng/m3 to 9.83±0.97ng/m3. No correlation is observed between MBP and gaseous phosphine. [Copyright &y& Elsevier]

Intensive use of plastic films can induce contamination of microplastics (MPs) and phthalate esters (PAEs), but data on their relationship in agricultural soil has been scarce. This study investigated the occurrence of MPs and PAEs in Shouguang (SG) and Xuzhou (XZ), two typical facility agriculture areas in China with years of history of vegetable greenhouse plantation. Thirty-four soil samples covering greenhouse and non-greenhouse soils were collected. MPs were quantified using the laser direct infrared (LDIR) method to realize IR analysis for all the collected particles. The total MP and PAE was 380–3786 pieces/kg and 0.30–1.58 mg/kg, respectively. The MP content in greenhouse soil was significantly higher than that in non-greenhouse soil in both areas. However, this trend for PAEs was only found in XZ, but not in SG. A positive correlation was observed between MPs and PAEs in XZ but not in SG. Our results suggested that MP concentrations mainly depend on input, while the residue of PAEs in soil was a consequence of both input and removal. Even in the facility soil, MPs and PAEs may not always possess a definitive relationship, and other environmental factors must be considered to elucidate the relationship between them. [Display omitted] • Soil microplastics (MPs) and phthalate esters (PAEs) from two areas were measured. • The laser direct infrared method was used to quantify MP number, type, and size. • MPs were higher in greenhouse soil than in non-greenhouse soil in both areas. • A positive correlation was found between MPs and PAEs in Xuzhou not in Shouguang. • MPs and PAEs may not always have certain relationship even in greenhouse soil. [ABSTRACT FROM AUTHOR]