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The present study focuses on an efficient Cr(VI)-reducing bacterial strain (CR-2) isolated from an abandoned chromate plant in Qinghai Province, China. CR-2 was confirmed as Lysinibacillus cavernae using 16S rRNA gene sequencing. CR-2 could survive at 500 mg L−1 Cr(VI) and effectively reduce Cr(VI) at concentrations of <50 mg L−1, a pH of 5–9, a temperature of 20–40 °C, and a salinity of 5–15 g L−1. According to the Box–Behnken experimental design, the maximum Cr(VI) removal efficiency by L. cavernae CR-2 was 76.21% under optimum conditions, which comprised a pH of 6.68, a temperature of 28.90 °C, and a salinity of 9.85 g L−1. With regard to Cr(VI) reduction mediated by L. cavernae CR-2, enhancement in efficiency was observed in the presence of Cu2+ and Ca2+, while significant inhibition in the reduction capacity occurred upon exposure to Mg2+, Ba2+, Ni2+, Pb2+, or Cd2+. Moreover, L. cavernae CR-2 tends to use glucose as an electron donor for the reduction of Cr(VI). Results of cell fraction separation and degeneration indicated that the Cr(VI) removal was primarily due to the reduction of Cr(VI) via chromium reductase in the cytoplasm. In addition, bioanalysis of L. cavernae CR-2 by SEM-EDS and TEM-EDS suggested that Cr was distributed both on the surface and in the cell cytoplasm. FT-IR analyses established that multiple functional groups (hydroxyl, carbonyl, amide, amino, and aldehyde groups) participated in the Cr(VI) biosorption on the cell surface. XPS and HPLC also showed that the Cr(III) end-products could be present as Cr(III) hydroxides or as organic–Cr(III) complexes. This study yields insights into the Cr(VI) bioreduction mechanism of L. cavernae CR-2. [ABSTRACT FROM AUTHOR]

Groundwater is one of most important available water resources in Chengdu Plain. It is sole drinking water in some rural areas, while the concentration of some areas could not meet the drinking water standards. Thus, it is significant to investigate the relationship between the concentration of Cr(VI) and land use types. The concentration of Cr(VI) in 102 groundwater sampling wells were obtained, and the spatial distribution of hexavalent chromium in groundwater was interpolated by Kriging interpolation method. Then, the land use types were analyzed by ENVI. Contributing area surrogate models were employed to investigate the influence of land use type on the concentration of Cr(VI). The following results were obtained, (1) the hexavalent chromium concentrated in crop land, flower-plant/forest land and greenhouse land. (2) The "contributing area surrogate" for the hexavalent chromium pollution region is circular area with a radius of 1750 m. And the pollutant of hexavalent chromium in region groundwater has a good correlation with greenhouse and crop land. [ABSTRACT FROM AUTHOR]

In the environment, chromium usually exists in both the trivalent and hexavalent states. Cr(VI) is of particular concern because it is highly toxic. However, it remains challenging to conduct field detection for trace concentrations of different valence states of Cr. Here, we propose a method based on laser-induced breakdown spectroscopy (LIBS) combined with an ion enrichment chip (IEC) to rapidly and sensitively detect the total Cr and Cr(VI) in water and soil. This method was termed IEC–LIBS. A chip with a millimetric channel was used for separating and enriching total Cr and Cr(VI) and LIBS was used for detection. The limits of detection (LoDs) of total Cr and Cr(VI) in water were 10 μg L−1 and 4 μg L−1, respectively, and the recoveries from spiked pool water ranged from 90 to 114%. The method also had good quantitative ability for soil detection, with total Cr and Cr(VI) LoDs of 13.6 mg kg−1 and 3.8 mg kg−1, respectively. The detection sensitivity of this method met the Cr environmental quality standards in China, and the detection time was within 20 min. IEC–LIBS is a simple and environmentally friendly method for detecting trace Cr in different valence states, and it is expected to be useful for field application. [ABSTRACT FROM AUTHOR]

This study conducted a nationwide specific assessment of soil chromium (Cr) contamination status in 506 of China's industrial regions. The overall soil Cr concentrations were 0.74–37,967.33 mg/kg, and the soil Cr content in 4.15% of the regions exceeded the reference screening value (2500 mg/kg). Geochemical accumulation index (Igeo) and monomial potential ecological risk index (E) revealed Cr salt production and tanning were the primary control industries. The non-carcinogenic risks posed by Cr salt production and tanning industries were higher than the national average values, and children were the most vulnerable groups. The heavily polluted regions were mainly located at the Yangtze River Delta, the Bohai Rim, the Pearl River Delta, the Yangtze River Basin, and the Yellow River Basin. The Yangtze River Delta was further identified as the high priority control area based on the class distribution of Igeo and E. Regression analysis showed the soil Cr concentrations in industrial regions increased during 2002–2009 and then turned into a declining trend in 2009–2021. This paper gives detailed insights into soil Cr pollution status in industrial regions across China and the results may serve as references for formulating tailored control measures for different industries and areas. [ABSTRACT FROM AUTHOR]

With the rapid development of industry, chromium (Cr) pollutants accumulate constantly in the soil, causing severe soil Cr pollution problems. Farmland Cr pollution hurts the safety of agricultural production and indirectly affects human health and safety. However, the current situation of Cr pollution in farmland soil and crops has not been detailed enough. In this study, the evaluation of Cr potential risk in soil-crop systems was conducted in a rural area that was affected by industry and historic sewage irrigation. Ten different crops and rhizosphere soils were sampled from four fields. The results showed that Cr contents in farmland soil exceeded the national standard threshold in China (>21.85%), and the Cr content in edible parts of some agricultural products exceeded that too. According to the PCA and relation analysis, the Cr accumulation in edible parts showed a significant correlation with soil Cr contents and available potassium contents. Except for water spinach, the target hazard quotient (THQ) of the other crops was lower than 1.0 but the carcinogenic health risks all exceeded the limits. The carcinogenic risks (CR) of different types of crops are food crops > legume crops > leafy vegetable crops and root-tuber crops. A comprehensive assessment revealed that planting water spinach in this area had the highest potential risk of Cr pollution. This study provided a scientific and reliable approach by integrating soil environmental quality and agricultural product security, which helps evaluate the potential risk of Cr in arable land more efficiently and lays technical guidelines for local agricultural production safety. [ABSTRACT FROM AUTHOR]

Microbial remediation, utilizing reduction of Cr(VI) to Cr(III), is considered a promising method for lowering toxic environmental chromium levels. In this study, a Cr(VI)-resistant fungal strain, Fusarium proliferatum S4 (F. proliferatum), was isolated from seriously chromium-polluted soil at Haibei Chemical Plant, China. This strain for treatment chromium-containing solution resulted in 100.00%, 93%, and 74% removal at initial concentrations of 10, 30, and 50 mg L−1 Cr(VI), respectively, after 12 days of treatment in a batch mode. Contributions of different cell fractions to Cr(VI) removal were explored. The Cr(VI) removal capacity of various cell components from strong to weak was as follows: cytoplasm, cell secretions, and cell debris. Observations obtained by scanning electron microscopy and transmission electron microscopy with energy dispersive X-ray spectroscopy revealed that not only the cell surfaces but also the intracellular contents were involved Cr through adsorption, reduction, or accumulation. Fourier transform infrared spectra indicated that a large number of functional groups (amino, carbonyl, carboxyl, and phosphate groups) participated in chromium binding on the cell surface. X-ray photoelectron spectroscopy confirmed the presence of Cr on the cell surface only as Cr(III). The results have important implications for an in-depth understanding of microbial chromate reduction by F. proliferatum. This study provides an insight into the microbial Cr(VI) bioreduction efficiency, and mechanisms in the chromium-contaminated environment. [ABSTRACT FROM AUTHOR]

Summary: Hexavalent chromium resistance and reduction mechanisms of microorganism provide a critical guidance for Cr(VI) bioremediation. However, related researches are limited in mesophiles and deficient for thermophiles. In this work, a novel alkaline Cr(VI)‐reducing thermophile Anoxybacillus flavithermus ABF1 was isolated from geothermal region. The mechanisms of Cr(VI) resistance and reduction were investigated. The results demonstrated that A. flavithermus ABF1 could survive in a wide temperature range from 50°C to 70°C and in pH range of 7.0–9.0. Strain ABF1 showed excellent growth activity and Cr(VI) removal performance when initial Cr(VI) concentration was lower than 200 mg L−1. 93.71% of Cr(VI) was removed at initial concentration of 20 mg L−1 after 72 h. The majority of Cr(VI) was found to be reduced extracellularly by enzymes secreted by cells. XPS and Raman analysis further manifested that Cr2O3 was the product of Cr(VI) reduction. Moreover, the Cr(VI) transportation‐related gene cysP and Cr(VI) reduction‐related gene azoR of A. flavithermus ABF1 played key roles in inhibiting Cr(VI) entering cells and promoting extracellular Cr(VI) reduction respectively. This work provides novel insight into the mechanisms of Cr(VI) resistance and detoxication of thermophiles, which leads to a promising alternative strategy for heavy metal bioremediation in areas with elevated temperature. [ABSTRACT FROM AUTHOR]

The relationship between the migration process and speciation distribution of Cr is important for the risk assessment in the underground environment. In this work, soil columns were collected from the chromate production site, with a 40-year operation, in the groundwater depression cone area of North China plain. The relationship between chromium pollution features and the geochemical properties of soil was established, and the migration risk of Cr(VI) was assessed based on the Nemerow composite index and Hydrus-1D model. The maximum total Cr concentration in the chromium slag dumping site reached 907 mg/kg, and that in the chromate production workshop was more than 200 mg/kg across the depth. The migration of Cr might be accelerated in the soil with abundant Mn (236–1461 mg/kg) but scarce organic matters (< 0.45%). The Hydrus simulation indicated that Cr(VI) would reach a cumulative flux of 300–729 mg/cm2 after 50 years. [ABSTRACT FROM AUTHOR]

Purpose: High chromium (Cr) in groundwater is a potential environmental issue worldwide that seriously threatens people's health. However, which Cr forms and species in aquifer solids control Cr mobility in the sedimentary aquifer is poorly understood. We hypothesize that Cr(VI) species, Cr(III) oxidation potential, and the potential of Cr(VI) release in aquifer sediments regulate dissolved Cr in aquifer systems. In this study, we have chosen the Baiyangdian Basin as the study area to investigate this hypothesis. Materials and methods: Thirty-one samples were collected from a borehole with a depth of 600 m in the study area for geochemical analysis. In addition to physicochemical characteristics of sediments, the Cr(VI) release potential and Cr(III) oxidation potential in sediments were analyzed. Results and discussion: Results revealed that total Cr contents in sediments ranged from 4 to 192 μg g−1 and total hexavalent chromium [Cr(VI)] contents accounted for 39.5% (average) of total Cr contents. The partition coefficients (Kd) of Cr, the ratio of adsorbed Cr in sediments to dissolved Cr in depth-matched porewater, were evidently higher in shallow aquifer systems (0.04–0.15 L g−1) than in deep aquifer systems (0.02–0.10 L g−1) hosting high Cr(VI) groundwater. Cr(VI) in sediments can be naturally generated and released into groundwater, especially at depths between 300 and 430 m below land surface with high concentrations of dissolved Cr(VI). Strong positive correlations were found between dissolved Cr in porewater and the potential of trivalent chromium [Cr(III)] oxidation or the potential of Cr(VI) release in sediments, indicating that Cr(III) oxidation and Cr(VI) release were conducive to the enrichment of dissolved Cr in porewater. Sediments in deep aquifers with weakly alkaline pH were also favorable for Cr(III) oxidation and Cr(VI) release. Conclusions: Cr tended to be enriched in sediments in the relatively reducing shallow aquifer, while in the oxic deep aquifer, Cr was enriched in porewaters. Concentrations of dissolved Cr in porewater were positively related with adsorbed Cr forms, the oxidation potential of Cr(III), and the release potential of original Cr(VI) in aquifer sediments. This study provides new insights into mechanisms of Cr mobility in non-mafic, deep sedimentary aquifers. [ABSTRACT FROM AUTHOR]

Magnesia–chrome brick has been abandoned in the use of Ruhrstahl Heraeus (RH) degasser in China for hexavalent chromium (Cr6+), a reaction product, is classified as carcinogenic potential. Because continuous Al-leading reaction behind the hot face results in the formation of a dense network of interwoven whisker in the matrix as temperature gradient moves, an unburnt periclase–spinel–Al brick has been affirmed as an alternative, with an advanced bonding system that can effectively reduce the penetration of slag and Fe melt, generate superior flexibility and hot strength to resist rapid-flow melt attack and thermal circulations, and present minor positive value of permanent expansion to ensure the closed joints of monolized lining when switching to lower temperature. A whisker bond is defined to be critical for the pronounced performance and extensive application of the unburnt periclase–spinel–Al bricks in RH degassers to substitute magnesia–chrome brick in steel refining process. [ABSTRACT FROM AUTHOR]

Understanding chromium (Cr) migration and dispersion patterns in the soil-groundwater system is critical for the control and remediation of subsurface Cr contamination. In this study, a typical Cr-contaminated site from the Pearl River Delta (PRD) in China was simulated with a three-dimensional (3D) sandbox experiment to investigate the migration and transformation behavior of Cr. Results revealed that under the combined influence of rainfall and groundwater flow, a complex flow field favorable for 3D migration and solute dispersion was formed. The flow field characteristics were influenced by water-table depth, which in turn affected Cr behavior in the system. Moreover, downward flow field expansion under low water-table conditions led to Cr vertical migration range expansion, causing greater contamination in the deep soil. The migration process was accompanied with Cr(VI) reduction, during which approximately 75 % of the total Cr was immobilized in soils. The reactive transport model achieved a good fit for Cr retention and morphological distribution in the solid phase. The model indicates that Cr is more readily transported and dispersed with groundwater, and Cr migrated and spread downstream by 15 m during the eighth year. Therefore, managing water-table depth could be a strategy to minimize the Cr vertical migration and contamination. [Display omitted] • A sandbox experiment was used for Cr migration and diffusion patterns. • Low water-table conditions led to Cr vertical migration range expansion. • Approximately 75 % of the total Cr was immobilized in the soil. • The model achieved a good fit for Cr retention and morphological distribution. [ABSTRACT FROM AUTHOR]

To address the secondary pollution problem of chemical reduction and the defects of a long bioremediation period for the soil around a chromium (Cr) salt plant in China, calcium polysulfide (CPS) combined with biostimulation (adding nutrient solution with glucose and urea) was used to reduce and stabilize hexavalent chromium [Cr(VI)] in the soil. The results showed that the remediation effect of adding CPS and nutrient solution was better than that of CPS alone for Cr(VI)-contaminated soil. An amount of 2.15% CPS with the Cr(VI) concentration reduced to approximately 330.0 mg/kg was selected as the optimal reducing agent dosage. Following the addition of 11 g/kg glucose and 13 g/kg urea, the degradation rate of Cr(VI) reached over 92% after 3 days, and the water-soluble fraction decreased by 95.6% after 40 days. The stability of the Cr was significantly enhanced. The correlation and regression analyses of Cr speciation indicated that the water-soluble fraction had significant negative correlations with the iron-manganese (Fe-Mn) oxide-bound fraction and the organic matter-bound fraction. There were significant negative correlations between the exchangeable fraction and the carbonate-bound fraction as well as extremely significant positive correlations between the Fe-Mn oxide-bound fraction and the organic matter-bound fraction. It was speculated that both the Fe-Mn oxide-bound fraction and the organic matter-bound fraction were transformed from the water-soluble fraction, and the exchangeable fraction and the carbonate-bound fraction were mutually transformed. This study enables us to acquire more knowledge about the speciation transformation of Cr in soil and provides an efficient, low-cost, and low-risk technology for the remediation of high Cr(VI)-contaminated soil. [ABSTRACT FROM AUTHOR]

This study discussed the mechanism of Fe-modified biochar (FeBC) derived from rice straw biochar (BC) as an adsorbent for removing Cr(VI) from aqueous solution and assessed its applicability in actual industrial wastewater. The Cr(VI) removal percentage increased with the FeBC dose, which achieved a removal of 99.5% at 8.0 g/L FeBC. Increasing the solution pH from 2 to 10 slightly reduced Cr(VI) adsorption by 6.6%. Coexisting ions such as Ca2+, Na+ and Cl− inhibited the removal of Cr(VI); the removal rate decreased to 60% at their concentration of 0.25 mol/L. The adsorption isotherm and kinetics were better described by the Langmuir isotherm and pseudo-second-order kinetic models, respectively. Through scanning electron microscopy with energy dispersive X-ray, the Brunauer–Emmett–Teller method, Fourier transform infrared, X-ray diffraction and X-ray photoelectron spectroscopy, the analysis revealed that FeBC with iron oxides loaded onto its surface had more active sites than BC; the surface functional groups changed; the removal of Cr(VI) by FeBC was mainly attributed to electrostatic adsorption; the redox reaction of Cr, and Fe loaded onto BC enhanced Cr(VI) reduction process. FeBC showed a good removal performance on actual industrial wastewater with the concentration of both total Cr and Cr(VI) meeting the integrated wastewater discharge standard of China. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Chemical oxidation processes are widely used for the remediation of organically contaminated soils, but their potential impact on variable-valence and toxic metals such as chromium (Cr) is often overlooked. In this study, we investigated the risk of Cr(Ⅲ) oxidation in soils during the remediation of 2-chlorophenol (2-CP) contaminated soils using four different processes: Potassium permanganate (KMnO 4), Modified Fenton (Fe2+/H 2 O 2), Alkali-activated persulfate (S 2 O 8 2−/OH−), and Fe2+-activated persulfate (S 2 O 8 2−/Fe2+). Our results indicated that the KMnO 4 , Fe2+/H 2 O 2 , and S 2 O 8 2−/Fe2+ processes progressively oxidized Cr(III) to Cr(Ⅵ) during the 2-CP degradation. The KMnO 4 process likely involved direct electron transfer, while the Fe2+/H 2 O 2 and S 2 O 8 2−/Fe2+ processes primarily relied on HO• and/or SO 4 •- for the Cr(III) oxidation. Notably, after 4 h of 2-CP degradation, the Cr(VI) content in the KMnO 4 process surpassed China's 3.0 mg kg−1 risk screening threshold for Class I construction sites, and further exceeded the 5.7 mg kg−1 limit for Class II construction sites after 8 h. Conversely, the S 2 O 8 2−/OH− process exhibited negligible oxidation of Cr(III), maintaining a low oxidation ratio of 0.13%, as highly alkaline conditions induced Cr(III) precipitation, reducing its exposure to free radicals. Cr(III) oxidation ratio was directly proportional to oxidant dosage, whereas the Fe2+/H 2 O 2 process showed a different trend, influenced by the concentration of reductants. This study provides insights into the selection and optimization of chemical oxidation processes for soil remediation, emphasizing the imperative for thorough risk evaluation of Cr(III) oxidation before their application. [Display omitted] • Environmental risk associated with Cr(III) oxidation was investigated in the remediation of 2-CP contaminated soil. • Cr(III) in soil oxidized gradually during 2-CP degradation in the KMnO 4, Fe2+/H 2 O 2 , and S 2 O 8 2−/Fe2+ processes. • The KMnO 4 process generated the highest content of Cr(VI) at 5.75 mg kg−1 among all tested systems. • The S 2 O 8 2−/OH− process demonstrated the lowest Cr(III) oxidation risk. • Direct electron transfer mediated the oxidation of Cr(III) in the KMnO 4 process. [ABSTRACT FROM AUTHOR]

There is sufficient evidence suggesting that exposure to hexavalent chromium [Cr(VI)] can cause a decline in lung function and the onset of lung diseases. However, no studies have yet explored the underlying mechanisms of these effects from various perspectives such as systemic inflammation, oxidative stress, and cellular senescence, simultaneously. This cross-sectional study was conducted among 304 workers engaged in chromate production and processing in China. Urine was used for detection of 8-hydroxy-2′-deoxyguanosine (8-OHdG) and 8-iso-prostaglandin F2α (8-iso-PGF2α), while RNA and DNA extraction from peripheral blood cells was used for detection of mRNA, telomere length, and ribosomal DNA copy numbers (rDNA CNs). A 2.7-fold elevation in blood chromate (Cr) corresponded to a 7.86% (95% CI: 2.57%, 13.42%) rise in urinary 8-OHdG and a 4.14% (0.02%, 8.42%) increase in urinary 8-iso-PGF2α, indicating that exposure to chromates can cause oxidative stress. Furthermore, strong correlations emerged between blood Cr concentration and mRNA levels of P16, P21, TP53, and P15 in the cellular senescence pathway. Simultaneously, a 2.7-fold elevation in blood Cr associated with a −5.47% (−8.72%, −2.1%) change in telomere length, while rDNA CNs (5S, 5.8S, 18S, and 28S) changed by −3.91% (−7.99%, 0.34%), −9.4% (−15.73%, −2.6%), −8.06% (−14.01%, −1.69%), and −5.86% (−10.67%, −0.78%), respectively. Structural equation model highlighted that cellular senescence exerted significant indirect effects on Cr(VI)-associated lung function decline, with a mediation proportion of 23.3%. This study provided data supporting for 8-iso-PGF2α, telomere length, and rDNA CNs as novel biomarkers of chromate exposure, emphasizing the significant role of cellular senescence in the mechanism underlying chromate-induced lung function decline. [Display omitted] • A cross–sectional study was undertaken among chromate workers. • Blood chromium was positively correlated with urinary 8-OHdG and 8-iso-PGF2α. • Blood chromium was negatively correlated with telomere length in peripheral blood cells. • Blood chromium was negatively correlated with rDNA copy numbers in peripheral blood cells. • Cellular senescence mediated lung function reduction induced by chromate. Synopsis: Chromate, categorized as a "Group I Human Carcinogen" and listed as "Top 20 Hazardous Substances", is associated with various chronic respiratory diseases. This study explores the mechanism of chromate exposure induced lung function decline from multiple dimensions, including oxidative damage, systemic inflammation, and cellular senescence. [ABSTRACT FROM AUTHOR]

• Chromium is a crucial indicator of farmland soil pollution. • Hyperspectral analysis is an efficient method for rapidly estimating Cr content. • An optimal hyperspectral model for predicting Cr content of farmland soil is needed. • The best spectral transformation and characteristic wavebands were obtained. • The SD-PLSR (R2 = 0.903, RMSE = 40.363) was the optimal hyperspectral estimation model. Heavy metal contamination of farmland soils is a severe concern worldwide. Chromium (Cr), a major environmental carcinogen, is a crucial indicator of farmland soil pollution. Compared with conventional chemical analysis, the hyperspectral analysis is superior in accurately and rapidly surveilling heavy metals in soils. However, various heavy metals, and types or geochemical traits of soils often affect the accuracy of hyperspectral estimation models, which makes guaranteeing the concentration estimation precision for a designated heavy metal in different regions considerably challenging. We here propose an optimal hyperspectral model for determining the Cr concentration of farmland soils first time in the Yanqi Basin of China's northwest arid zone. In total, 171 soil samples were gathered, and their Cr concentrations and relevant spectral reflectance data were determined. The best spectral transformation for measuring the Cr concentration was determined by using 12 transformation types of soil spectral curves, and characteristic wavebands were obtained. Then, by using random forest (RF), support vector machine (SVM), and partial least squares regression (PLSR) models, we constructed hyperspectral estimation models for Cr concentration in farmland soils. The estimated results of these models were compared to identify the best estimation model. Results show that the spectral transformations allow an improvement in the association between the soil Cr concentration and spectra. The accuracy of PLSR was significantly higher than that of SVM and RF. Finally, the second-order differentiation (SD) combined with the PLSR model (R2 = 0.903, RMSE = 40.363, MAE = 30.631) was identified as the optimal model for estimating the Cr concentration of farmland soils in the investigated area. The study findings offer a technical reference for the hyperspectral assessment of the Cr concentration in arid zone farmland soils. [ABSTRACT FROM AUTHOR]

Purpose: High-silicon chromium iron (HSCI) has been used in ground grids in southern China, while there was a lack of study on its corrosion behavior in this soil environment. The purpose of this paper is to discover the corrosion of HSCI in acidic and alkaline soil solutions. Design/methodology/approach: The original defects on the HSCI surface were observed using optical microscopy, and the corrosion behavior of the HSCI in the acidic and alkaline soil solutions were jointly detected using electrochemical measurements and scanning electron microscopy/energy dispersive spectrometer. Findings: The results showed the corrosion rates of the HSCI in the acidic and alkaline soil solutions were limited, and the high contents of Cr and Si in matrix was responsible for its high corrosion resistance. The HSCI showed a similar corrosion tendency in the two solutions, while its corrosion rate in the acid soil solution was higher than that in the alkaline soil solution. The corrosion pits on the specimen surface were originated from the original defects in matrix, and the edges of the corrosion pits were more rounded than the original defects after 720 h immersion in the two solutions. The original defects in the HSCI matrix played a significant role in the corrosion process. Originality/value: The paper discovered the corrosion evolution of HSCI in the acidic and alkaline soil solutions. What is more, the acceleration role of the original defects on the corrosion of the HSCI in the acidic and alkaline soil solutions was discovered in the paper. The results are beneficial for the material selection of ground grid equipment in engineering. [ABSTRACT FROM AUTHOR]

Hexavalent chromium [Cr(VI)]-contaminated soils have introduced a serious problem in China. Cr(VI) is hazardous to both the environment and public health and may degrade the engineering properties of soils. Accordingly, the effects of Cr(VI) on the physicochemical, mechanical, and microstructure properties of Chinese clay were investigated in this study. Results show that Cr(VI) had a considerable negative effect on the physicochemical, mechanical, and microstructure properties of soil. Specifically, Cr(VI) changed the physicochemical properties and degraded the mechanical properties of soil, led to the aggregation of soil particles, and created a large void space. Cr(VI) also changed the mineral composition of the soil and converted clay minerals into calcite. The changes in the microstructure and mineral composition of the soil were the primary reasons for the differences in the engineering properties of Cr(VI)-contaminated soil. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background. Soil contamination by hexavalent chromium is becoming a main environmental concern in China. This study developed a sewage sludge biochar modified by FeSO4 (CHBC) as a new reductant for Cr(VI)-contaminated soil. The effectiveness of CHBC-stabilized Cr(VI)-contaminated soil was investigated. Methods. Typical industrial Cr(VI)-contaminated soil in China was chosen as the medium. The total and Cr(VI) contents of the contaminated soil were 1014.6 and 973.5 mg/kg, respectively. The effectiveness of the Cr(VI)-contaminated soil stabilized by CHBC was investigated by the leaching test (US EPA method 1312), the simplified bioaccessibility extraction test (US EPA 2007 protocol and British Geological Survey), alkaline digestion (US EPA method 3060A), sequential extraction (BCR sequential extraction procedure), X-ray diffraction, and the risk assessment code test. Results. Results show that CHBC substantially reduced the leachability and Cr(VI) content of the contaminated soil. The leachability and content of Cr(VI) were lower than the thresholds of the Environmental Quality Standards of Soil in China for civil reuse and the China Environmental Quality Standards of surface water for civil use when the soil was stabilized with 10% dosage of CHBC. Conclusion. CHBC is highly efficient in stabilizing Cr(VI) and can effectively reduce the leachability and bioavailability of Cr in contaminated soil and thus feasible for stabilizing Cr(VI)-contaminated soil and shows potential for application in the field. [ABSTRACT FROM AUTHOR]

With the rapid advancement of industrialization without effective supervision, industrial aquatic toxic metal (TM) emissions pose threats to human health in China. Due to differences in socioeconomic development, the regional disparity of industrial aquatic TM emissions is obvious nationwide. In this study, the human health impacts (HHIs) of industrial aquatic TM emissions (i.e., mercury (Hg), cadmium (Cd), hexavalent chromium (Cr(VI)), lead (Pb), and arsenic (As)) in the 31 provinces of China were evaluated based on the ReCiPe method, and the driving factors affecting HHIs from 2000 to 2015 were decomposed using the logarithmic mean Divisia index (LMDI) method. The results showed that the HHIs gradually decreased, with more than an 80% decrease from 2000 to 2015. The order of the TMs contributing to the national HHIs in 2015 was as follows: As (79.5%) > Cr(VI) (19.6%) > Hg (0.4%) > Pb (0.2%) = Cd (0.2%), and 21 (68%) provinces were dominated by industrial aquatic As emissions. Economic development is the major driving factor of the increase in HHIs, while the HHI strength and wastewater discharge intensity are the key driving factors causing reductions in the HHIs. Hunan, Inner Mongolia, Hubei, and Jiangxi accounted for approximately 55% of the total HHIs in 2015. Some suggestions for reducing HHIs based on the local realities of different provinces were put proposed considering two aspects: economic strategy and technical capability. [ABSTRACT FROM AUTHOR]

Background: With the acceleration of urbanization, heavy metal contamination in subsurface water and groundwater is becoming more and more serious, and the interaction between surface water and underground water is an important factor that cannot be ignored. Based on the change of oxygen content in surface water and groundwater environment, this research mainly studied the influencing factors and mechanism of underground mineral element Fe(II) on the morphological transformation of heavy metal Cr(VI) under the condition of surface–groundwater interaction, and simulates the interaction process of subsurface–groundwater by changing the dissolved oxygen content in the redox reaction system of dissolved Fe(II) and Cr(VI). The influence mechanism of pH, Fe(II):Cr(VI), groundwater hardness ion and humic acid on the morphological transformation of Cr(VI) was investigated. Results: The results showed that the content of DO did affect the conversion of Cr(VI) by Fe(II). pH had a great influence on the redox reaction: while pH = 3–5, the reaction rate of Fe(II) and Cr(VI) and the removal rate of Cr(VI) decreased with the increase of pH; while pH = 6–8, the reaction rate and the removal of Cr(VI) increased with the increase of pH. When Fe(II):Cr(VI) = 3:1, the reaction of Fe(II) and Cr(VI) is affected by DO; when Fe(II):Cr(VI) is 1:1, 2:1, 4:1 and 5:1, DO has no obvious effect on the reaction. Groundwater hardness ions can greatly promote the redox reaction. When humic acid exists in the reaction system, the Fe(III) formed by the oxidation of Fe(II) by Cr(VI) will once again be converted into soluble Fe(II), the reduction of humic acid further promotes the redox reaction between Fe(II) and Cr(VI), and promotes the conversion of Cr(VI) by Fe(II) more effectively. Moreover, the higher the concentration of humic acid, the higher the removal rate of Cr(VI). Conclusions: The research results have practical guiding significance for groundwater contamination prediction, pollution control and remediation, integrated water resources management and the construction of sponge city in China. [ABSTRACT FROM AUTHOR]

Exposure to toxic air pollutants (TAPs) is linked to the development of cancer and various chronic health issues. While studies on the ambient characteristics of criteria air pollutants such as particulate matter, nitrogen oxides, and ozone have been extensively conducted, research on TAPs in China remains limited. In particular, there has been a lack of long-term observation studies on the potential health risks associated with ambient TAP concentrations. To address this gap, we characterize the long-term trends (2000–2020) of a wide range of TAPs in Hong Kong using ambient monitoring data derived from a TAP monitoring program that has been in operation since the late 1990s. We analyzed TAPs such as diesel particulate matter (DPM), volatile organic compounds, carbonyl compounds, polycyclic aromatic hydrocarbons, hexavalent chromium, and others. We found that most of the TAPs decreased notably over the last two decades, translating to a reduction in economic loss of over HK$2 billion per year in 2016–2020. However, the current state of TAPs still poses significant health risks. The total TAP concentrations in 2016–2020 exceeded the chronic reference guideline value for noncancer health hazard quotient of 1.0 (1.53). The aggregated inhalation cancer risks in the corresponding period were 562.8 in a million population. We found that the top ten TAPs disproportionately accounted for more than 80% of both health estimators. In contrast to earlier years where DPM dominated the cancer risks, the measured VOCs have grown in importance, and they pose cancer risks as significant as DPM in recent years. Our work identifies several areas in enhancing TAP monitoring, which have implications for expanding the monitoring across the Greater Bay Area for improving air quality management from a health-oriented perspective. • Ambient TAP concentrations in HK decreased notably between 2000 and 2020, bringing substantial health and economic benefits. • Current state of TAP concentrations continues to pose substantial cancer and chronic noncancer health risks. • Few leading TAPs account for >80% of health risk estimators; risks associated with VOCs become comparable to diesel exhaust. [ABSTRACT FROM AUTHOR]

The rapid industrial growth has generated heavy metal(loid)s contamination in the soil, which poses a serious threat to the ecology and human health. In this study, 580 samples were collected in Henan Province, China, for source apportionment, migration characterization and health risk evaluation using self-organizing map, positive matrix factorization and multivariate risk assessment methods. The results showed that samples were classified into four groups and pollution sources included chromium slag dump, soil parent rock and abandoned factory. The contents of Cr, Pb, As and Hg were low in Group 1. Group 2 was characterized by total Cr, Cr(Ⅵ) and pH. The enrichment of total Cr and Cr(Ⅵ) in soil was mainly attributed to chromium slag dump, accounting for more than 84.0%. Group 3 was dominated by Hg and Pb. Hg and Pb were primarily attributed to abandoned factory, accounting for 84.7% and 70.0%, respectively. Group 4 was characterized by As. The occurrence of As was not limited to one individual region. The contribution of soil parent rock reached 83.0%. Furthermore, the vertical migration of As, Hg, Pb and Cr(Ⅵ) in soil was mainly influenced by medium permeability, pH and organic matter content. The trends of As, Pb, and Hg with depth were basically consistent with the trends of organic matter with depth, and were negatively correlated with the change in pH with depth. The trends of Cr(Ⅵ) with depth were basically consistent with the changes in pH with the depth. The content of Cr(Ⅵ) in the deep soil did not exceed the detection limits and Cr(Ⅵ) contamination occurred in the deep aquifer, suggesting that Cr(Ⅵ) in the deep groundwater originated from the leakage of shallow groundwater. The assessment indicated that the non-carcinogenic and carcinogenic risks for children and adults could not be neglected. Moreover, children were more susceptible than adults. [Display omitted] • Multivariate approach provides reliable results for source apportionment. • Pollution sources including anthropogenic activities and geogenic were identified. • The vertical migration characteristics of As, Hg, Pb and Cr were investigated. • The pollution of deep groundwater came from the leakage of shallow groundwater. • Non-carcinogenic and carcinogenic risk for children and adults could not be ignored. [ABSTRACT FROM AUTHOR]

Chromium and its compounds are widely used in many industries in China and play a very important role in the national economy. At the same time, heavy metal chromium pollution poses a great threat to the ecological environment and human health. Therefore, it's necessary to safely and effectively remove the chromium from pollutants. In practice, there are many factors which influence the removal efficiency of the chromium. However, few studies have investigated the relationship between multiple factors and the removal efficiency of the chromium till now. To this end, this paper uses the green synthetic iron nanoparticles to remove the chromium and investigates the impacts of multiple factors on the removal efficiency of the chromium. A novel model that maps multiple given factors to the removal efficiency of the chromium is proposed through the advanced machine learning methods, i.e., XGBoost and random forest (RF). Experiments demonstrate that the proposed method can predict the removal efficiency of the chromium precisely with given influencing factors, which is very helpful for finding the optimal conditions for removing the chromium from pollutants. [ABSTRACT FROM AUTHOR]

Hexavalent chromium (Cr6+) is highly toxic and mobile in groundwater, and abundant in regions of high industrialization. To assess the status and migration influences of Cr6+ in groundwater, its distribution and influencing factors in a regional groundwater system of Sanmenxia Basin, north-central China, were investigated by monitoring changes in concentration along with hydrochemical characteristics in both shallow and deep aquifers. Groundwater samples were collected from 86 sites including 42 shallow wells (depth ≤ 100 m) and 44 deep wells (depth > 100 m) in several aquifer zones. Fifty-six samples (23 shallow and 33 deep wells) contained Cr6+concentrations ranging from 0.004 to 0.192 mg/L, with many of the high chromium concentration points in the deep wells. There was a positive trend between groundwater depths with chromium concentration. The formation of high concentration of hexavalent chromium in deep well water is significantly affected by the hydrochemical characteristics (pH, Eh, etc.) and chemical composition of groundwater (coexistence of inorganic and organic substances). The accumulation of chromium has been favored by the alkaline environment in this study area, where a relatively high concentration of chromium (>0.05 mg/L) is associated with a relatively high pH value (>7.7). Moreover, F-, Cl-, K+, Na+, HCO3-, CO32, SO42-, Fe3+, and TDS had positive trends with Cr6+, while Ca2+, Mg2+, NO3 - and total hardness had negative trends with Cr6+. In addition, COD, dichloromethane, trichloromethane, and 1,2-dichlorobenzene detected in the groundwater negatively correlated with Cr6+ under current study conditions. These findings are crucial for hexavalent chromium accumulation and migration assessment in groundwater exploitation in this region. [ABSTRACT FROM AUTHOR]

The three-dimensional electrokinetic remediation (3D EKR) achieved efficient removal of chromium (Cr) from the soil through mechanisms including electromigration, electroosmosis, and redox reactions. In this study, the long-term stability, leaching toxicity, bioavailability, and phytotoxicity of Cr in remediated soils were systematically analyzed to comprehensively evaluate the effectiveness of the 3D EKR method. The results showed that the concentration of hexavalent chromium (Cr (VI)) in the leachate of the 3D EKR system with sulfidated nano-scale zerovalent iron (S-nZVI) was more than 40% lower than those of the other 3D electrode groups, and the time required to reach the level III standard of groundwater quality criterion in China (0.05 mg/L, GB/T 14848-2017) was significantly shortened. The stabilization of Cr(VI) in contaminated soil after 3D EKR was maintained for 300 pore volumes (PVs), indicating that the treated Cr(VI) had good long-term stability. The leaching toxicity and bioaccessibility of Cr were assessed by the synthetic precipitation leaching procedure (SPLP), the toxicity characteristic leaching procedure (TCLP), and the physiologically based extraction test (PBET). The concentration of Cr(VI) in the SPLP, TCLP, and PBET leachates of the S-nZVI group decreased by more than 25% compared to the other 3D electrode groups, corresponding to the decrease in leaching toxicity and bioavailability of the treated Cr during the 15-day remediation period. In addition, the germination rate of wheat seeds and the average biomass of wheat seedlings in the S-nZVI group under alkaline conditions (EE) were higher than those in the non-polluting group (Blank-OH), indicating that the remediated soil had no obvious toxicity to wheat. In summary, 3D EKR achieved a satisfactory and stable remediation effect on Cr-contaminated soil, especially when using S-nZVI as the 3D electrode. [Display omitted] • 3D EKR with S-nZVI achieves the best remediation effect for Cr-contaminated soil. • S-nZVI has been proven the most efficient 3D electrode for Cr(VI) removal (≥81.03%). • Cr in the soil can be stabilized for at least 360 days after 3D EKR remediation. • 3D EKR reduced the leaching toxicity of Cr in soil, especially in S-nZVI group. • No obvious phytotoxicity was found in the S-nZVI group under the alkaline condition. [ABSTRACT FROM AUTHOR]

Objective: To analyze the disease burden and change trend of lung cancer attributable to chromium in Chinese population from 1990 to 2019, and to provide reference for the formulation of health policies and strategies of disease prevention and control. Methods: In October 2022, using the data and findings of the burden of disease, injury and risk factor published in the Global Burden of Disease Study 2019 (GBD 2019), the burden of lung cancer and its changes caused by occupational hexavalent chromium exposure in Chinese population from 1990 to 2019 were analyzed according to year and gender. The average age structure of the world population was used as the standard population to calculate standardized indicators, and then compared with the global population. Results: The incidence number, death number, disability adjusted life years (DALY) of lung cancer attributable to chromium in Chinese population of 2019 were 833 cases, 790 cases and 22118 person years, respectively. Compared with 1990 (257 cases, 277 cases, 8631 person years), the increase was 224.1%, 185.2%, 156.3%, higher than the global level (101.0%, 134.2%, 117.2%). The standardized morbidity, mortality and DALY rates of lung cancer attributable to chromium in Chinese population of 2019 were 0.059/100000, 0.056/100000 and 1.555/100000, which respectively increased by 169.7%, 137.4%, 113.3% in comparison with that of 1990 (0.022/100000, 0.023/100000 and 0.729/100000). The average annual percent changes were 18.8%, 15.1% and 13.5%, which were higher than the global level (5.7%, 8.4% and 7.0%). In 2019, the DALY caused by chromium-related lung cancer in the Chinese population accounted for 0.0058% (22118/382205568) of the all-cause disease burden in the Chinese population, and 51.8% (22118/42718) of the global population. In 2019, the disease burden of lung cancer attributable to chromium was higher in males than in females, the number of incidence, death and DALY were 576 cases (69.1%), 525 cases (66.5%) and 14717 person years (66.5%), respectively. Conclusion: In 2019, the proportion of disease burden caused by lung cancer attributable to chromium in the Chinese population is low, but it accounts for a high proportion of the global population burden of lung cancer attributable to chromium, and the standardized incidence, mortality and DALY rates show an increasing trend year by year from 1990 to 2019.

The ubiquitous ureolytic microbes were potential to clean up toxic heavy metals from environment. Their responses and detoxification mechanisms are largely unknown for multiple metals in field soils. In this study, high-throughput sequencing of the urease-encoding genes and deep learning from bioinformatic analysis were conducted for identifying ureolytic prokaryote-related processes throughout China. The passive adsorption of heavy metals onto cell walls or cell surfaces was mainly performed by G+ ureolytic bacteria in soils located in the large-scale smelting areas with slightly high Hg and low Cu/Zn/Ni contents. For the large-scale smelting areas with the highest Cr and lowest Cu/As contents, the Cr(VI) was reduced to Cr(III) by G– ureolytic bacteria and then accumulated in their periplasmic spaces or cell surfaces. The G– ureolytic bacteria detoxified high contents of multiple metals by intracellular antioxidant defense mechanisms and extracellular urease-induced (co)precipitation in the medium-scale smelting areas, consistent with high urease activities and ureolytic microbial diversity. In addition, this large-scale field work verified that toxic metals stimulated the bacterial hydrolysis of urea as soil nitrogen fertilizers and depressed the bacterial fixation of nitrogen from air. Simultaneously, the heavy metals used nitrate-N and nitrite-N as alternative electron acceptors, driving the soil denitrification processes. [Display omitted] • We focused on ureolytic microbe-related remediation of toxic metals across China. • High-throughput sequencing of functional gene was against partial 16S rRNA genes. • Urease and ureolytic microbe were distinct at large- and medium-scale smelting areas. • Three detoxification pathways in ureolytic microbes were found for metal pollution. • Detoxification of toxic metals was linked to transformations of elemental N in soils. [ABSTRACT FROM AUTHOR]

Due to the toxicity, bioaccumulation, non-biodegradability and perseverance of heavy metals, their risk assessment is essential for soil quality management. The Hakanson potential ecological risk index (RI), which considers the effects of heavy metal concentration and toxicity, has been widely used in soil ecological risk assessment. However, RI overlooks the influence of soil properties on the mobility and availability of heavy metals in risk assessment. To fill this gap, this study sought to develop an improved ecological risk index (IRI), which incorporates soil adsorption into RI, and applied it to evaluate the ecological risk of heavy metals in the soil of the Taihu basin, China. The soil adsorption models based on the Gradient Boosting Decision Tree (GBDT) was used to predict the soil adsorption capacity of five heavy metals (i.e. cadmium, chromium, copper, lead, zinc). The soil adsorption capacity in 1446 sites in the Taihu basin was predicted by the GBDT models and was assigned as the weight of IRI. The risk assessment results of the five metals in the Taihu basin showed that 40% of the sites were at a moderate risk level and 60% of the sites were at a slight risk level based on the RI. The value of IRI in the basin ranged from 11.1 to 75.5, with a mean value of 28.1. IRI differed from RI in spatial distribution due to the influence of soil adsorption. The comparative analysis between the metal contents in sediments and surrounding soils confirmed the tremendous influence of soil adsorption on ecological risks, indicating that soil adsorption should be taken into consideration in soil risk assessment. [Display omitted] • Soil adsorption was assigned as the weight to modify the traditional risk index. • Machine learning models are effective tools to predict soil adsorption capacity. • Soil adsorption affects the mobility of heavy metals and reduces their risk. • The heterogeneity of soil properties changes the risk distribution of heavy metals. [ABSTRACT FROM AUTHOR]

Objective: To evaluate whether Club (Clara) cell protein (CC16) and surfactant-associated protein D (SP-D) can be used as biomarkers for lung injury caused by chromium exposure. Methods: The concentrations of chromium in the air (CrA), chromium in the blood (CrB), lung function, CC16, SP-D, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) were detected in 91 chromium-exposed workers and 38 controls. Results: In chromium-exposed group, the levels of CrA, CrB, SP-D, TNF-α, and IL-6 were significantly higher, whereas forced expiratory volume in one second (FEV1), FEV1/FVC, maximal expiratory flow (MEF), maximum ventilation volume (MVV), CC16, and CC16/SP-D were lower. Negative correlations were shown between CC16, SP-D or CC16/ SP-D, and CrB or inflammatory cytokines (TNF-α and IL-6). Positive relationships were shown between CC16 or CC16/SP-D with indicators of lung function. Tobacco smoking and chromium exposure had synergic effects on lung injury. Conclusions: CC16, as an immunosuppressive protein, and CC16/SP-D can be used as sensitive and noninvasive biomarkers for lung injury. Smoking should be banned in chromium workplaces. [ABSTRACT FROM AUTHOR]

Rapid detection methods are needed to investigate the environmental quality risk of soil and groundwater in contaminated lands. Currently there is lack of rapid detection methods to sensitively and accurately analyze contaminations of hexavalent chromium in soil due to the challenge of complex sample pretreatment or expensive instrumentation. Here we report a rapid accurate detection platform for quantifying hexavalent chromium in soil and groundwater with ultrasensitivity. The platform consists of a novel sensor of microProbing beads and a portable microscope. Each microProbing bead was a nanoliter reactor to selectively sequestrate Cr (VI) with the enrichment factor up to 150 ×. The microProbing beads presented the signal uniformity of ~97% for the statistical colorimetric imaging analysis. Combined with a miniaturized microscope, the microProbing beads allowed for detecting aqueous Cr (VI) and soluble Cr (VI) in soil within 45 min. The platform achieved high sensitivity with the detection limits of 0.003 ppb for aqueous Cr (VI) and 0.07 ppm for soil Cr (VI). It accurately detected soil and groundwater samples from a chromium contaminated land in Yangtze River Basin of China. The consistency to the laboratory standard methods was achieved with the low cost of ~0.20 US dollar per test. The microProbing imaging platform with the operational simplicity and device portability is highly promising for the field analysis of Cr (VI) in contaminated lands. [Display omitted] • The microProbing beads sequestrate Cr (VI) by an enrichment factor of ~150 ×. • The microProbing imaging platform is accurate, ultrasensitive, portable and low-cost. • The platform quantified Cr (VI) in soil and groundwater from a contaminated land. [ABSTRACT FROM AUTHOR]

To clarify the removal trends of typical pollutants in recharged water samples during soil aquifer treatment (SAT), especially the recharging performances in the funnel areas of arid regions, the Zibo-Weifang funnel area of China was selected as an example where the effects of dry-wet ratio (DWR, the ratio of the dry period to irrigation period), wet period duration (WPD, duration of one irrigation period), irrigation side length (ISL) and irrigation depth (ID) on the 50-year SAT performance were simulated using HYDRUS-2D. Experimental results revealed that the operational parameters of the DWR, WPD, ISL and ID exhibited significant effects on the bulk removal of chemical oxygen demand (COD), nitrate (N O 3 −), ammonium (N H 4 +), total phosphorus (TP) and hexavalent chromium (C r 6 +). Eventually, the optimal conditions with a DWR of 3, WPD of 7 d, ISL of 100 m, and ID of 200 cm were selected for the SAT based on the simulations, and irrigation loads as high as of 84.12 m/yr were obtained. During the 50-year irrigation simulation, as much as 256 Mm3/yr of new water would be recharged into the Shandong Plain, which would be accompanied by the effective removal of COD, N H 4 + , TP and C r 6 + . In contrast, the N O 3 − concentrations within the obtained SAT effluent (50 m depth) were higher than those of the influent, which were closely related to the insufficient carbon sources in the deep soil and poor soil adsorption capacity. Thus, a more stringent threshold value for the nitrate reinjection concentration (e.g., 12 mg/L) was proposed. In addition, the pollutants, N O 3 − , N H 4 + , TP and C r 6 + all exhibited a penetration potential and posed potential pollution threats, especially under higher irrigation loads. Therefore, appropriate pretreatment measures should be strongly considered for the practical operation of SAT systems. [Display omitted] • Simulated the efficiency of SAT in different operating conditions at actual scale. • N O 3 − concentration increased after SAT under different operating conditions. • The concentration of N O 3 − in influent should be limited to less than 12 mg/L. • Significant correlation existed in the removal of N H 4 + with COD and TP (R 2 >0.8). • The penetration risk exhibited the following trend: N O 3 − ≫ C r 6 + N H 4 + >TP. [ABSTRACT FROM AUTHOR]

A coupled methodology of nitrogen isotopes, hydrogeochemical characterization, multivariate statistical analysis, and SIAR Bayesian modeling has been employed to identify the sources of NO 3 and N transformation processes in three alluvial aquifers (Schinos, Thiva, and Central Evia) located in central Greece where geogenic Cr(VI) co-occurs with agricultural activity and rural development. Hexavalent chromium concentrations exceed 50 μg/L in many sampling stations of the studied groundwater bodies, while nitrate contamination is evident in all three study areas with concentrations well over 50 mg/L. The mean δ - and N transformation processes in three alluvial aquifers (Schinos, Thiva, and Central Evia) located in central Greece where geogenic Cr(VI) co-occurs with agricultural activity and rural development. Hexavalent chromium concentrations exceed 50 μg/L in many sampling stations of the studied groundwater bodies, while nitrate contamination is evident in all three study areas with concentrations well over 50 mg/L. The mean δ 15 N-NO 3 - and δ 18 Ο-NO 3 - values are 6.67 ± 1.77‰ and 2.68 ± 1.77‰ in C. Evia, 8.72 ± 4.74‰ and 3.96 ± 4.57‰ in Schinos and 4.44 ± 1.71‰ and 2.91 ± 1.02‰ in Thiva, respectively. Domestic sewage and N-bearing fertilizers are contributing in various degrees to the observed nitrification which is the dominant transformation process of N in the studied aquifers. Multivariate statistics indicated that the main processes identified in the study areas are salinization, silicate dissolution, and groundwater contamination due to fertilizer use. It is suggested that ultramafic rock-related alluvial aquifers must be closely monitored in terms of nutrient inputs as an effective measure for controlling Cr(VI) release in groundwater., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Abstract: Chromium contamination in soils and natural waters is a significant environmental concern. Remediation efforts often rely on the conversion from the highly toxic Cr(VI) to Cr(III) which has lower toxicity and less environmental mobility. In the present study, the catalytic role of soils in the transformation of Cr(VI) to Cr(III) by two organic acids containing α-OH groups was investigated with or without light. Three types of widely distributed soils in China, Yellow-brown, Chernozem and Red Soils, were examined. The results demonstrated that the presence of soils markedly facilitated the Cr(VI) reduction by organic acids. Without light, the average rate of Cr(VI) reduction by citric acid with 25g L−1 soil was increased by 3.9 (Red Soil), 17.5 (Chernozem) and 44.8 times (Yellow-brown Soil), respectively as compared with control (without soil). For tartaric acid, it was 2.6 (Red Soil), 4.2 (Chernozem) and 6.6 times (Yellow-brown Soil) as much as the control. With light and at 1.5g L−1 soil loading, the average rates of Cr(VI) reduction increased from 6.2 (citric acid alone) to 27.8 (Red Soil), 44.6 (Yellow-brown Soil), and 57.7μM h−1 (Chernozem), an increase of 4.5, 7.2 and 9.3 times, respectively. Tartaric acid showed weaker soil-induced enhancement of photochemical reduction of Cr(VI) than citric acid. The reaction rates in all three soil suspensions added with tartaric acid tended to be approximately the same. Our findings suggest that the catalytic role of soils in the reduction of Cr(VI) by organic acids is mainly from Mn(II) in soil without light and from iron ions in soil with light. [ABSTRACT FROM AUTHOR]

The Sphingomonas paucimobilis biomass has been successfully utilized to degrade several persistent organic pollutants (POPs). However, few studies have been conducted to use it to remove heavy metals from aqueous solutions. In the present study, biosorption experiments for Cr (VI) were investigated using nonliving biomass of S. paucimobilis isolated from activated sludge, Lianyungang Dapu sewage treatment plant, China. The effects of several parameters including solution pH, contact time, and ionic strength, etc. on Cr (VI) uptake were studied. The biomass was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS) and Fourier transform infrared spectrometer (FTIR). The applicability of the Langmuir and Freundlich models was tested. The correlation coefficients (R) of both models were greater than 0.95. The maximum adsorption capacities were found to be 28.5 mg/g for Cr (VI) at 20°C. The adsorption process was quick and found to follow the pseudo-second-order equation. The optimum adsorption was achieved at pH 2. The adsorption was also NaCl concentrations dependent. [ABSTRACT FROM AUTHOR]

In this work, the use of chemical reduction combined with microbial stabilization to remediate Cr(VI) in contaminated soil was systematically investigated. The effectiveness, phytotoxicity and microbial diversity resulting from the combination of ferrous sulfate with microbial stabilization by biogas solid residue (BSR) were determined. The stabilization experiments showed that the optimum Cr(VI) conversion rate of 99.92% was achieved with an Fe (II)/Cr(VI) molar ratio of 3:1, a BSR dose of 5.2% (wt), and a water content of 40%. Under these conditions, the residual Cr(VI) content was 0.80 mg/kg, which satisfied the risk screening value (≤ 5.7 mg/kg) for soil contamination of land for general development in China. The remaining Cr(VI) level was stable for 90 days during the chemical reduction and biogenic stabilization process. Moreover, Zucconi test analysis suggested that the soil phytotoxicity to Brassica campestris L. disappeared. The results of microbial diversity analysis indicated that the bacterial community changed significantly during chemical reduction and microbial stabilization processes, and Bacillus, Pseudomonas and Psychrobacter may participate in the reduction of Cr(VI) into Cr(III). • The optimum Cr(VI) conversion rate of 99.92% was achieved. • The safety and stability of Cr(VI) level remained stable for 90 days. • The soil phytotoxicity of Brassica campestris L. decreased significantly. • BSR significantly enhanced Cr(VI) reduction and stabilization. [ABSTRACT FROM AUTHOR]

• Proximal soil sensing is still attractive in Cr estimation. • Fractional order derivative and three-band index are useful for feature extraction. • The correlation and mechanism analysis between auxiliary attributes and chromium. • Concatenation of Proximal soil sensing and auxiliary attributes is promising. • Kriging and optimal semi-variogram function are essential in soil science. The rapid and accurate determination of soil chromium (Cr) is crucial for preventing toxic element pollution in soils and ensuring ecological security. Proximal sensing technology uses visible and near-infrared (Vis-NIR) diffuse reflectance spectroscopy, which has been demonstrated to be a viable approach for monitoring soil Cr concentrations. However, at trace levels, soil Cr is not especially spectrally active, thus limiting the practical application of using corresponding spectral data for quantifying soil Cr concentrations. In this study, we hypothesized that fused proximal sensing and soil auxiliary attributes (including organic matter (OM) and pH) could improve estimation of Cr concentrations in the soil. Additionally, the introduction of best-fit variogram models was theoretically possible to improve spatial visualization. To address these hypotheses, we collected 168 soil samples from the open coal mine area in the Eastern Junggar Basin, China. Fractional-order derivative (FOD) pretreatment and optimal band combination methods were implemented for spectral data mining and the derivation of spectral parameters, respectively. Soil Cr estimation models were calibrated with a partial least squares (PLS) approach through four designed strategies with different predictors: (I) full Vis-NIR variables, (II) effective three-band spectral indices (TBIs), (III) the effective TBIs and OM, and (IV) the effective TBIs, OM, and the pH. The results suggest that FOD could identify abundant spectral variability. Compared with full Vis-NIR variables, the effective TBIs can effectively magnify the subtle spectral signals concerning soil Cr. The optimal estimation model was determined as Strategy IV, indicating that the introduction of soil auxiliary attributes (pH and OM) can improve the estimation performance of the model; notably, the coefficient of determination (R 2) and ratio of performance to interquartile distance (RPIQ) were 0.87 and 2.68, respectively. Based on the optimal semivariance model, we used kriging interpolation to map regional soil Cr. In the study area, the soil Cr distribution features strong spatial dependence and strong associations. Our study might inspire further research on soil contamination mapping based on proximal Vis-NIR sensors. [ABSTRACT FROM AUTHOR]

China has the largest textile production and export in the world, with a massive amount of wastewater and related pollutants releasing. With an increasing concern to improve water quality, dyeing and finishing wastewater (DFW) requires better disposal or reclamation. In this review, the characteristics of wastewater in different natural and synthetic fiber production processes as well as the origins of their specific pollutants such as aniline, absorbable organic halogens (AOX), sulfide, hexavalent chromium and antimony were summarized. The discharge standards for DFW in China, have undergone complex evolution processes, which were discussed including the current standard, the revision detail and the one to be implemented. Furthermore, the current status of pollutant reduction in the textile industry, covering cleaner production and wastewater treatment, was targeted, in particular the state of the art of specific pollutant removal technologies and their feasibility of application for DFW treatment. Also, reclamation systems based on wastewater discharge characteristics and reclaimed water quality requirements were reviewed. Overall, the systematic solution of source reduction of wastewater and contaminants, coupled with subsequent treatment and recycling, is crucial for the sustainable development of the textile industry. • Wastewater characteristics in different fiber production processes were summarized. • Dyeing and finishing wastewater discharge standard evolution in China was reviewed. • Specific pollutant removal technologies and their feasibility were discussed. • Systematic solution for wastewater treatment is given for sustainable developing. [ABSTRACT FROM AUTHOR]

An enrichment consortium and an isolate (isolate TKW) of sulfate-reducing bacteria (SRB) have been obtained from metal-contaminated marine sediments of Tokwawan, Hong Kong SAR. These bacteria are capable of reducing highly toxic and soluble hexavalent chromium (Cr6+) enzymatically into less toxic and insoluble trivalent chromium (Cr3+) under anaerobic conditions. The enrichment consortium almost completely (98.5%) reduced 0.6 mM Cr6+ in 168 h and the rate of reduction was 0.5 g (Cr6+) g (protein)−1 h−1. In comparison, with Cr6+ as the sole electron acceptor (as a surrogate for SO42−), isolate TKW reduced 94.5% of the initially added Cr6+ (0.36 mM) in 288 h, with the rate of 0.26 g (Cr6+) g (protein)−1 h−1. Adsorption by these bacteria was not the major mechanism contributing to the transformation or removal of Cr6+. The biomass and Cr3+ in the cultures increased simultaneously with the reduction of Cr6+. These indigenous SRB might have potential application in bioremediation of metal contaminated sediments. [Copyright &y& Elsevier]

Among the toxic metals, hexavalent chromium [Cr(VI)] has attracted much attention due to its high mobility and toxicity, rendering considerable challenges for long-term remediation. In this study, the soil was collected from a dichromate contaminated industrial site in Liaoning Province, a seasonally frozen area in northern China, and subjected to frequent freeze-thaw cycles. Three additives, including (i) ferrous sulfate; (ii) calcium polysulfide; and (iii) combined biochar and calcium polysulfide were applied to reduce and immobilize Cr(VI) in the soils. The samples underwent 28 days of incubation followed by 16 freeze-thaw cycles. The toxicity characteristic leaching procedure (TCLP) and simulated acid rain leaching were adopted to test the remediation performances. It was observed that all three treatments can significantly reduce and immobilize Cr(VI) after short-term incubation, while biochar with abundant functional groups could adsorb and reduce Cr(VI) effectively. Notably, the concentration of Cr(VI) in TCLP leachates after incubation in combined treatment decreased by 67.87% and 37.27%, respectively, compared with the application of ferrous sulfate or calcium polysulfide alone. Freeze-thaw cycles induced the disintegration of soil particles and increased the risk of contaminant mobilization. Conversely, biochar particles has become finer and even produced nanoparticles with ageing, accompanied by the increase in oxygen-containing surface functional groups. Additionally, the specific surface area increased with the pyrolysis of biochar, which further enhanced the retention of soil colloidal particles and suppressed the migration of contaminants. Therefore, the cumulative release of Cr(VI) in the combined treatment (i.e., 10.97 ~ 32.97 mg/kg) was much lower than that of the other two treatments after freeze-thaw ageing. Overall, the combination of biochar and calcium polysulfide displayed advantages in the reduction and immobilization of Cr(VI), and offered a long-term, effective strategy for the remediation of Cr(VI) contaminated soils in cold regions. [Display omitted] ● Application of biochar plus calcium polysulfide enhanced Cr(VI) immobilization. ● Immobilization was associated with reduction and surface complexation. ● Freeze-thaw ageing re-mobilized soil Cr(VI). ● Biochar particles became finer and even produced nanoparticles with ageing. ● This amendment is suitable for long-term remediation of seasonally-frozen areas. [ABSTRACT FROM AUTHOR]

In December of 2019, a total of 114 river water samples were collected from 38 sampling sites in the Xiujiang River of the Poyang Lake Basin for three consecutive days. The temperature (T), pH, dissolved oxygen (DO), chemical oxygen demand (CODCr), five-day biochemical oxygen demand (BOD5), total nitrogen (TN), ammonia nitrogen (NH4+-N), total phosphorus (TP), and concentrations of heavy metals (Cr, Cu, Zn and As) of the samples were measured. The results showed that the average concentrations of heavy metals in the mainstream of the Xiujiang River were Cu > Zn > Cr > As, and those in the main tributary of Xiujiang River (named as the Liaohe tributary) were Zn > Cu > Cr > As, which met the class III of the Environmental Quality Standards for Surface Water in China. However, it was founded that TN and NH4+-N in some agricultural areas had not met the class III standard of surface water. Hierarchical clustering analysis grouped sampling sites into four clusters. Clusters 1, cluster 2, cluster 3, and cluster 4 corresponded to an urban industrial area, rural mountainous area, primitive mountainous area, and agricultural area, respectively. The majority of the sampling sites were classified as mountainous rural areas less impacted by human activities, while the Liaohe tributary were urban industrial areas impacted more by human activities. Principal component analysis and correlation analysis results showed that variation of heavy metals and nutrient elements in Xiujiang River is related to the heterogeneity of human activities, which is mainly affected by urban industrial and agricultural pollution, and natural environments of the river with different background values. The results obtained in the current study will potentially provide a scientific basis for the protection and management of freshwater resources and aquatic ecosystems in the Xiujiang River and Poyang Lake Basin. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) from abandoned coal mines can lead to serious environmental problems due to its low pH and high concentrations of potentially toxic elements. In this study, soil pH, sulfur (S) content, and arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), nickel (Ni), zinc (Zn), iron (Fe), manganese (Mn), and mercury (Hg) concentrations were measured in 27 surface soil samples from areas in which coal-mining activities ceased nine years previously in Youyu Catchment, Guizhou Province, China. The soil was acidic, with a mean pH of 5.28. Cadmium was the only element with a mean concentration higher than the national soil quality standard. As, Cd, Cu, Ni, Zn, Mn, Cr, and Fe concentrations were all higher than the background values in Guizhou Province. This was especially true for the Cd, Cu, and Fe concentrations, which were 1.69, 1.95, and 12.18 times their respective background values. The geoaccumulation index of Cd and Fe was present at unpolluted to moderately polluted and heavily polluted levels, respectively, indicating higher pollution levels than for the other elements in the study area. Spatially, significantly high Fe and S concentrations, as well as extremely low pH values, were found in the soils of the AMD sites; however, sites where tributaries merged with the Youyu River (TM) had the highest Cd pollution level. Iron originated mainly from non-point sources (e.g., AMD and coal gangues), while AMD and agricultural activity were the predominant sources of Cd. The results of an eco-risk assessment indicated that Cd levels presented a moderate potential ecological risk, while the other elements all posed a low risk. For the TM sites, the highest eco-risk was for Cd, with levels that could be harmful for aquatic organisms in the wet season, and may endanger human health via the food chain. [ABSTRACT FROM AUTHOR]

The migration and redox transformation processes of toxic Cr(VI) in the upper and deep soil of chromate-polluted site are of great importance for the environmental risk control and soil remediation. In this study, soils from surface to deep (around 30–60 m) and the groundwater in a typical abandoned chromate production plant site which has experienced decades of contamination were both sampled and analyzed. The results show that the soil in the leaching workshop of Cr(VI), dichromate transformation workshop and chromium slag dumping ground exhibits severe contamination of chromium and the pollution has extended to the groundwater, causing serious pollution in groundwater too. The vertical migration and transformation of Cr(VI) in the soil layer are mainly affected by the soil permeability, organic matter content and the amount of water passing through the soil layer. During the downward migration, Cr(VI) tends to be retained by the clay layer and further accumulates around the depth of 5–10 m where the concentrations of both hexavalent and total Cr reach maximum values, and then continues to diffuse from the accumulation layer towards the deeper soil. Accompanying with the reduction of Cr(VI) by organic matter in the soil, the Cr(III) exists at various depths. When the depth is below the groundwater level of saturated aquifer, the distribution of chromium in the soil and groundwater reaches leaching and redox equilibrium due to the long-term interaction between the soil and groundwater. Image 1 • The soil and groundwater at chromium (VI) production workshops are severely polluted. • Chromium (VI) tends to be retained by the clay layer and peaks at a certain depth. • The main factors include soil permeability coefficient, reductant and elution water. • The migration and conversion mechanisms of chromium in polluted site are revealed. [ABSTRACT FROM AUTHOR]

Geochemical fluxes in rock-soil systems are important tools in the evaluation of soil environmental risk, especially where the geological background (parent materials) are enriched in potential toxic elements (PTE). In the Baoshan area, the presence of mineral resources along with carbonate and basalt parent materials often leads to PTE being elevated in soils. In this study, we compared rock and soil geochemical compositions by collecting rock samples from the host formations and ore samples from two mineral deposits (Cu–Pb–Zn and Fe–Cu–Pb–Zn) and their overlying soils. This research demonstrates enrichment of PTE (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) in soils relative to their parent materials. The enrichment in soils may be due to the removal of mobile elements (e.g., Ca, Na, Mg, and Sr), and coprecipitation (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) and/or adsorption by Fe-oxy-hydroxides (Cr and Ni) under the influence of high pH values during soil formation. The results point to a parent lithological origin and natural enrichment of PTE in Baoshan soils. However, anthropogenic contamination of soils near mining areas is also possible. Soils forming from carbonate rocks, basalts, and especially from mineralized formations have higher PTE concentrations, and in places, levels can exceed the risk screening values for soil contamination of agricultural land of China. Where the latter is the case, it is suggested that ecological monitoring be implemented in the study area. The conventional use of the geo-accumulation index (I geo) and enrichment factor (EF) methods is challenged in this research and found to underestimate the PTE contamination. A compositional data analysis approach (using clr biplots) is presented which shows that comparison with regional-scale background datasets is essential to provide a more informative approach to evaluate the risk of soil contamination, especially in regions with elevated levels of PTE in parent materials. • Geochemical flux of rock-soil systems are revealed for different geological formations. • The geochemical flux indicates a lithological origin for PTE. • I geo and EF may underestimate PTE contamination in regions with elevated PTE. • CoDA is used to take into account the relative nature of geochemical data. • Mining activities contributions to soil contamination of PTE near the mining areas. [ABSTRACT FROM AUTHOR]

• Preparation of a new Fe 2 O 3 loaded biochar from Enteromorpha prolifera biomass. • Adsorption of Cr on pristine and magnetic biochar was compared and analyzed. • EPFRs formation occurred at different pyrolysis temperatures and Cr concentration. • Toxicities of magnetic biochars to fresh algae Scenedesmus obliquus is reported. • Cellular response of Scenedesmus obliquus to EPFRs was studied. Enteromorpha prolifera (EP) biomass collected from a lake in China was employed for biochar production. The EP biochar was magnetically modified by loading γ-Fe 2 O 3 particles on the surface, and Cr(VI) adsorption behavior and mechanism were evaluated. The magnetic biochar had higher surface polarity, specific surface area and exhibited a higher Cr(VI) adsorption capacity of 95.23 mg/g biochar compared with pristine EP biochar. The pronounced electron spin resonance (ESR) signals showed that the environmental persistent free radicals (EPFRs) preferred to form at lower pyrolysis temperature and lower transition metal concentration. The g factors of BC400, BC800 and BCF400 were 1.8959, 1.7955 and 1.7954, respectively, indicating that the EPFRs mainly used carbon atom as center. In addition, biological toxicity of magnetic EP biochar was tested using the microalga Scenedesmus obliquus. Exposure of S. obliquus cells to magnetic biochar led to the accumulation of reactive oxygen species (ROS) and oxidative stress. The leaching solution toxicity of BCF400 was stronger than BCF800. Thus, the magnetic EP biochar prepared at higher temperature (such as BCF800) provide better Cr (VI) performance with low biologic toxicity. And the EP biomass could be a promising low-cost feedstock for biochar production. [ABSTRACT FROM AUTHOR]

• Eight exposure pathways including four environmental media and three exposure routes. • Calculate individual eight exposure doses with risk assessment equations. • Compare contribution of exposure dose from each pathway with ridge regression, WQS and BKMR. • Chromium exposure dose through ingesting dust contribute most to urine chromium. Environmental hexavalent chromium contamination in northeast China has been ongoing for over 60 years and health outcomes related with chromium (Cr) pollution were observed in polluted arears, but exposure pathways remains unclear. This study aims to evaluate the association between Cr exposure dose through multiple exposure pathways and Cr concentration in urine, and identify the most contributed pathway. We used risk assessment tools with individual exposure parameters to estimate eight individual Cr exposure doses (CD) for three exposure routes (inhalation, ingestion, and dermal contact) with four environmental media (underground water, soil, household dust, and PM 10 in ambient air) in 134 residents living in three chromium polluted villages. We used the covariate-adjusted standardized urinary Cr concentration (casUCr) as the internal Cr exposure biomarker. Ridge Regression, Weighted Quantile Sum Regression (WQS) and Bayesian Kernel Machine Regression (BKMR) models were used to assess the effect of overall eight CDs on urine Cr concentration and compare the contribution of each CD. In the ridge regression analysis, Cr exposure through ingestion of dust (βstd = 0.418, p-value = 0.009), inhalation of dust (βstd = 0.384, p = 0.031) and dermal contact with soil (βstd = 0.264, p = 0.192) had the highest impact on casUCr. In the WQS model, the overall CDs demonstrated a non-significant positive association with casUCr. CDs of dust ingestion, air inhalation and dust inhalation had the largest contribution on casUCr when fitted in the WQS model. In the BKMR model, the hierarchical variable selection showed that casUCr was mainly affected by CDs of household dust and dermal contact with soil. CD of dermal contact with soil exhibited a negative association with casUCr, while CDs of dust showed positive or non-linear trend. This research proposed a new method to calculate individual Cr exposure dose of multi-pathway and applied different statistical methods to identify predominant pathway. For this study, Cr exposure through dust has the strongest effect on Cr concentration in urine. The results could help conduct target interventions to reduce Cr intake, such as blocking dust exposure to reduce Cr uptake for villagers living in these contaminated areas. [ABSTRACT FROM AUTHOR]

• The potential of Dolichospermum flos-aquae for production biochar was investigated. • The microbe-biochar composite showed superior hexavalent chromium removal capacity. • Biochar can effectively protect microbe cells from the direct toxicity of chromium. • This study lead to development of a novel utilization of harmful algal biomass. In China, Dolichospermum flos-aquae is one of the most prevalent bloom-forming cyanobacteria and thus a major challenge for the concerned catchment area. To solve this problem and turn it into an opportunity for heavy metal remediation, we investigated the potential of D. flos-aquae for production algal biochar, and constructed a microbe-algal biochar composite. The microbe-biochar composite (biochar immobilized Proteus mirabilis PC801) showed superior hexavalent chromium removal capacity. It produced 100% Cr(VI) (150 mg/L) removal efficiency, with 87.7% total Cr immobilized in/on the particles and only 12.3% Cr(III) left in solution. Furthermore, Scanning electron microscopy-energy dispersive spectroscopy and antioxidase activity results showed that Cr(VI) reduction mainly occurred outside the cells, and the biochar can effectively protect P. mirabilis YC801 from the direct toxicity of chromium, thereby promoting the removal efficiency. Overall, this study provides a promising approach by utilizing this harmful algae for the bio-remediation of Cr(VI)-contaminated groundwater in practical application. [ABSTRACT FROM AUTHOR]