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Copyright of Food & Machinery is the property of Food & Machinery 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.)

In order to explore the effect of calcium on soil heavy metal Cd, four different calcifications were applied to the soil to study the effect of calcium on soil pH, bioavailability of soil Cd and chemical form of soil Cd. The results showed that with the application of calcium, the soil pH value gradually creased, and the soil gradually became alkaline. The application of calcium can promote the adsorption capacity of soil to Cd, resulting in a decrease in the bioavailability of soil Cd, and the form of soil Cd gradually changes to a stable state, and soil pH is significantly positively correlated with soil calcium content, soil oxidizable Cd and soil residual Cd. [ABSTRACT FROM AUTHOR]

It is of great significance to analyze the heavy metal speciation and identify the organic compounds in soil. By now, the most of existed methods can not be used for simultaneously analyzing metal-containing compounds and organic components, which require tedious sample preparation and offline separation processes before detection, increasing analytical errors and lengthening analysis time. Herein, based on our previous research, a novel electrochemical mass spectrometry (EC-MS) device was fabricated for online sequential qualitative detection of metal species and organics in soil without sample pretreatment. Firstly, the components were divided into four species, including water soluble, lipid soluble, insoluble and oxidable speciation, and then dissociated by extraction, reaction and electrolysis online. Ultrapure water and CH3OH were employed as eluents to extract water-soluble and lipid soluble species, respectively. EDTA-2Na (CH3OH:H2O=1:1, V/V) solution was used as reactant to dissociate insoluble speciation by chelation. For oxidable speciation, the electrolysis was applied to transform the elements into ions using EDTA2Na as an electrolyte. Then, the dissociated components were mixed with different charged reagents to form ions for MS detection. For example, the produced inorganic metal ions reacted with EDTA2Na in situ to form metal-EDTA chelate, the polycyclic aromatic hydrocarbons would chelate with Ag+ to form Ag+ -PAHs. For organic compounds, those were easily ionized, would be charged with CH3OH directly. Finally, the charged ions and chelates would be transferred for ESI-MS detection in real time under negative and positive ion modes, respectively. The soil sample collected from farmers’ own vegetable fields in the suburb near the roadside was analyzed by EC-MS. The results showed that the soil sample contains water-soluble Mg, Cr, Ni, Zn, Co, Cu, Al, Pb, urea and various organic amines, lipid soluble carboxylic acids, insoluble Ni, Cr, Pb, and oxidable Cu, Pb. The heavy metals in the sample may come from animal and plant waste, the settlement of road dust and atmospheric suspended particles, etc. Amines may come from urine, pesticides, biological tissues, etc. And the presence of organic acids were related to organisms. It indicated the potential of EC-MS for the rapid qualitative species detection of heavy metals and organics in soil. This method can solve the problems, such as low sensitivity, long analysis time, complex pretreatment operation, large sample dosage, and complex operation process, which can provide a strong technical support for environmental assessment and environmental governance. [ABSTRACT FROM AUTHOR]

China as a biggest producer of electrolytic manganese is in the imperative to ameliorate the soil pollution which caused by electrolytic manganese waste residue. In this study, a survey was undertaken at a electrolytic manganese residue storage in Caixi Village of the Yuping Dong-minority Autonomous County under the jurisdiction of Tongren City of Guizhou Province, where the largest reserve of manganese ore resources in China is situated. To understand the characteristics of soil pollution, the speciation distribution of heavy metals (incl. Mn, Zn, Pb, Ni, Cr and Cd), and ecological risk of heavy metal contamination of the soil around the electrolytic manganese residue storage were analyzed by wet digestion and BCR sequential extraction. Mn, Pb and Cd, inter alia, had caused the severest impacts on the environmental quality of soil: Mn concentration was in the range of 356~14 915 mg/kg, with an average of 3 828 mg/kg, being 4.8 times higher than the background value of the soil in Guizhou; and the average concentrations of Pb and Cd were 3.1 and 40.2 times, respectively, higher than the "risk screening values of the National Standard for Farmland Soil". As to the heavy metal speciation, six species of heavy- metal were mainly composed of migratory dissolved weak acid, and the content of dissolved fraction of weak acid of Mn and Cd in soil increased as the distance got closer towards the residue storage dam (P<0.05). According to the analytic result by using the common Kriging spatial interpolation, there existed a kind of moderate spatial correlation among the content of Mn, Cd, Zn, Pb and Ni; in addition, the content of Mn and Cd, among others, were randomly affected by the pollution of human activity considerably; and the spatial distribution of concentrations of Mn and Cd in general showed the higher in the east and lower in the west parts of the area being investigated, and the high values of Mn and Cd concentrations were found mostly near the dam of the waste residue storage; and the results of principal component analysis (PCA) indicated that Mn, Cd and Pb were mainly resulted from the pollution of electrolytic manganese residue, while the contamination sources of Ni and Zn could be traced to the nearby agricultural activities and industrial production. Furthermore, Cr was mainly affected by the geological background factors, the highest potential ecological risk level belonged to the soils in proximity to the waste residue storage, and particularly, the contribution ratio of Cd was the highest (91%). [ABSTRACT FROM AUTHOR]

Bioremediation of Cd-polluted soil using metal-resistant bacteria has received increasing attention. In the present study, pot experiments were conducted to investigate the changes in soil Cd speciations, rice grain Cd accumulation, and soil microbial community structure after different Delftia sp. B9 biomass inoculations in the soil. Additionally, the optimum additive amounts of B9 were applied in the field experiments to verify the reductions of Cd in rice grain. The results showed that all different treatments with B9 biomass inoculations significantly increased soil pH and decreased the content of bioavailable Cd (extracted by DTPA) by 4.72% - 15.65%. In comparison with CK, treatments with B9 addition decreased the Cd concentration in grains by 22.87%-59.90%; all grain Cd levels in the pot trials were within the acceptable range for food security in China (0.2 mg·kg-1) . T2 (B9 application：1.28 g·pot-1) was the most effective remediation treatment that enhanced soil Cd fractionations into more stable forms and significantly reduced Cd accumulation in rice grains. The treatment T2 significantly increased the operational taxonomic units (OTUs) and microbial community richness and diversity indexes (ACE, Chao1, and Shannon) . The relative abundance of Proteobacteria (B9 is a member of this phylum) increased significantly. The application rate of B9 was 12.50 g ·m-2, which significantly reduced the Cd accumulation by 28.38% - 91.43% for rice grains in field conditions. Studies have shown that the application of B9 reduces the potential environmental risks posed by Cd in soils and improves food safety. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group 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.)

Effects of different doses (0%, 1%, 2%, 4%) of straw biochar on soil nutrient and silicon speciation of two typical soils (paddy soil and lateritic red soil) in South China were investigated through soil culture experiment. The results showed that straw biochar application could significantly increase soil pH, total carbon and available potassium, and they were increased with the increase of doses of biochar application. In addition, biochar application increased the content of alkali hydrolyzable nitrogen in paddy soil, but the effect was opposite in lateritic red soil. Biochar also increased the content of different silicon chemical forms in two types of soil, 4% biochar application showed the highest increase. Compared with non-biochar treatment, 4% biochar application increased the content of CaCl 2 -Si, Acetic-Si, H 2 O 2 -Si, Oxalate-Si and Na 2 CO 3 -Si by 300.3%, 419.4%, 91.9%, 115.0% and 82.5% at the 10 the day in paddy soil, respectively, and increased by 864.9%, 1463.4%, 646.4%, 186.5% and 80.2% in lateritic red soil, respectively. This suggested that impacts of biochar on soil nutrient properties and silicon speciation were related to biochar application rate and soil type, and the effects were better in lateritic red soil than that in paddy soil. [ABSTRACT FROM AUTHOR]

Selenium (Se) is a trace element that plays a crucial role in human health. It has antioxidant, anti-cancer and anti-viral properties and is essential for a healthy body. The level of Se in the human body is largely dependent on daily dietary intake, which is in turn influenced by the amount of Se that enters the food chain from the soil. The global distribution of Se in soil is uneven, with a large difference in concentrations ranging mainly between 0.01-2.0mg/kg. The average abundance of Se in the Earth's crust is 0.07mg/kg, but in some Se-enriched areas, it can reach up to 1200mg/kg. The chemical behavior of Se in soils is complex and diverse, involving processes such as adsorption-desorption, precipitation-dissolution, oxidation-reduction, methylation-demethylation and complexation reactions, each of which affects the bioavailable Se and is influenced and conditioned by factors such as soil pH, soil organic matter, metal oxides, clay and microorganisms. Roots are the primary site for most plants to absorb Se, which is then transported, metabolized, and accumulated. Plants can directly absorb Se from the soil, including Se that exists in the form of free ions, carbonate-bound Se, and Se adsorbed on the surfaces of clay and humus in soil solutions. However, selenite and selenate can be reduced to solid, insoluble Se(0) and metal-Se precipitates that are not bioavailable in locally anaerobic areas (such as soil aggregates) or used by bacteria as terminal electron acceptors.Previous researchers have conducted a lot of work on chemical extraction methods, but there are still problems, such as insufficient extraction specificity and Se form transformation during the extraction process. Hence, an accurate approach for predicting the amount of soil Se that can be absorbed by plants is essential. However there are no clear paths for the choices of assessment methods and influencing factors of soil Se bioavailability. These problems have restricted the utilization of Se-enriched land resources. Thus, providing a scientific basis for the development and utilization of Se-enriched land resources is the goal here by summarizing the main assessment methods and dominant factors on soil Se bioavailability.Determining the activity of Se in soils comprehensively requires considering the complicated and varied effects of natural conditions on its bioavailability, which can be studied through characterization methods and identification of influencing factors. Therefore, it is of practical importance and a challenge to accurately determine the form of Se in soils and assess its bioavailability. Current methods for characterizing the bioavailability of soil Se include the traditional chemical extraction methods (single extraction and sequential extraction) and the emerging Diffusive Gradients in Thin films (DGT) technique. Chemical extraction is a process that involves separating a specific component or substance from a mixture using a solvent or a chemical reagent. The extraction method depends on the physical and chemical properties of the substance being extracted and the nature of the mixture. The general steps involved in a chemical extraction method are: choosing the appropriate solvent or chemical reagent that can selectively dissolve the desired substance while leaving the unwanted components behind, mixing the mixture and the solvent/reagent together to allow the selective extraction of the desired substance, separating the extracted substance from the mixture using various techniques such as filtration, centrifugation, or evaporation, and purifying and isolating the extracted substance by further chemical or physical methods if necessary. The DGT technique is an effective environmental chemistry method used for identifying elements and compounds in various aqueous environments, including natural waters, sediments, and soils. This technique is particularly useful for detecting bioavailable trace elements, and it can be applied for in-situ detection. The DGT technique involves using a specially-designed passive sampler that comprises a binding gel, a diffusive gel, and a membrane filter. The element or compound of interest passes through the membrane filter and diffusive gel before being assimilated by the binding gel in a rate-controlled manner. Subsequently, the binding gel is analyzed post-deployment, enabling the determination of the time-weighted-average bulk solution concentration of the element or compound via a simple equation.The advantages and limitations of chemical extraction methods, DGT technique and bioavailability assessment models of Se at a regional scale are compared. Traditional chemical extraction procedures such as single extraction or sequential extraction can be used to characterize the bioavailability of Se in the soil, to a certain extent. Still, the extraction process has many limits and incomplete extraction problems. The DGT method can be used to simulate the root uptake process of plants and can better characterize the bioavailability of Se compared to sequential extraction. One of the major advantages of the DGT technique is its ability to provide accurate and reliable results, even at low concentrations. Additionally, this technique is non-destructive and can be used in-situ, making it suitable for real-time monitoring of environmental conditions. However, there are also some limitations associated with the DGT technique. For instance, the binding gel used in this method may not be specific to the target element or compound, leading to the possibility of cross-reactivity with other substances. Additionally, the technique may be influenced by factors such as temperature, pH, and ionic strength, which could affect the accuracy of the results. Using large-scale crop-root soil samples, a soil-crop Se assessment model was developed with parameters of physicochemical indicators (e.g. soil pH, soil organic matter, soil Se, etc.), which can better predict Se bioavailability on a regional scale.Some major and minor influencing factors affecting the uptake of Se in soil by plants are discussed. In short, topography and soil type, Se species, pH and organic matter are the main factors affecting bioavailable Se, with plant species and soil aging as secondary factors.In brief, the main limitations of the characterization methods for the bioavailability of different forms of Se are: a single extraction method can be affected by soil properties, soil/solution ratio, extraction time, the pH value of the extraction agent, and other factors. Sequential extraction methods have problems with incomplete extraction, dilution of the extract, and Se loss during centrifugation and filtration. These traditional methods cannot be used to reflect the dynamic processes of the solid-phase soil-solution-root system. DGT technology is a method that disturbs the equilibrium between soil solution and solid phase, simulating the dynamic process of Se uptake by roots, and has advantages in assessing bioavailability. However, it is still questionable whether it can be used to fully predict the replenishment dynamics of Se in field soil. The main factors affecting the bioavailability of soil Se are: (1) Topographical factors such as altitude, slope, and terrain wetness index, which have some influence on soil Se content; there are large differences in organic matter, iron/aluminum hydroxides, and pH among different soil types, which can be controlled to affect Se migration and bioavailability; (2) Soluble and exchangeable Se are more easily absorbed by plants, and selenate with better mobility is easier to absorb, transport, and metabolize in plants than selenite; (3) Increasing soil pH can generally improve Se bioavailability, but this is not the case in organic-enriched soils. Currently, there is no universally applicable method for evaluating soil Se bioavailability, as it is influenced by many factors such as topography, soil type, and soil physicochemical properties. This makes it difficult to compare and verify different results. Improving in-situ DGT analysis technology and modifying the analysis of Se forms are important technical means for accurately evaluating soil Se bioavailability and are also important directions for future development.

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.)

Acid mine drainage (AMD) is an environmental problem commonly found in mining area. This paper collectively investigated the physicochemical parameters in AMD, and the speciation of heavy metals in the sediment and the associated risk of their re-mobilization in the Shirenzhang mine site. Results indicated that the aquatic systems suffered a combined pollution of heavy metals As, Zn, Cu, and Fe. The secondary Fe minerals in the sediments were capable of immobilizing the heavy metals and the immobilization affinity of minerals to As was stronger than that to Zn, Cu, and Cd. At pH<3, the well crystalline minerals including jarosite and ferroarsenite were detected in the sediments, and the heavy metals were mainly presented in the crystalline iron oxide-bound phase and the residual phase. The stability of heavy metals was relative high. At pH>3, however the poor crystalline iron oxyhydroxide including schwertmannite and β - Fe(OOH) were the dominant secondary minerals. And the heavy metals in the sediments were mainly presented in the surface-adsorbed phase and the poor crystalline iron oxide-bound phase, which led to a low stability of the heavy metals. In addition, the relative abundance of iron reducing bacteria was high in the sediments at pH>3, which might induce the transformation of the secondary minerals and the associated mobilization of heavy metals. These results provided important insights into the geochemical behavior of heavy metals in AMD environments. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group 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: Selenium is an essential trace element and a typical bifunctional element that can affect human health if consumed in insufficient or excessive amounts. The biological activity of selenium depends not only on its intake level but also on its chemical speciation. Selenium comes in various speciation and is divided mainly into inorganic and organic selenium. Inorganic selenium includes selenate [ Se (Ⅵ)] and selenite [ Se (Ⅳ)], and organic selenium mainly includes selenocysteine (SeCys2 ), selenomethionine ( SeMet), and methylselenocysteine (MeSeCys). It has been found that organic selenium has high bioactivity and bioavailability. At present, while the nutritional effects of selenium are drawing more and more attention, it is very important to analyze and study the different speciation of selenium in food. Since the analysis of selenium speciation is closely related to the sample matrix, the extraction efficiency and stability of different selenium speciation are also related to many factors. At present, the analysis method of selenium speciation in food is still in the research stage. Broccoli is rich in nutrients, such as protein, flavonoids, polyphenols, and vitamins, and is widely loved by people because it contains many kinds of thioglucosides and has a strong ability to gather selenium, which has antioxidant and anti)cancer medical values. Therefore, the analysis and study of selenium speciation in broccoli is of some significance. OBJECTIVES: To establish a method for the determination of Se(Ⅵ), Se(Ⅳ), SeCys2, MeSeCys, and SeMet in commercial broccoli by high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). METHODS: Firstly, the chromatographic conditions were selected by examining the separation and sensitivity of Se( Ⅵ), Se ( Ⅳ), SeCys2, MeSeCys, and SeMet on a Hamilton PRP - X100 anion column with 40mmol / L diammonium hydrogen phosphate (pH = 5 with 1% methanol) as the mobile phase and on a ZORBAX SB-Aq C18 reversed-phase column with 10mmol / L citric acid plus 5mmol / L sodium hexane -sulphonate ( pH = 4 with 1% methanol) as the mobile phase. Secondly, the sample pretreatment conditions were optimized, including the selection of extraction reagents, the amount of extraction reagents, and extraction time. Four extraction reagents ( ultrapure water, Tris - HCl buffer solution, proteinase XIV and complex proteinase ) were selected for optimization. The effect of proteinase XIV concentration on the extraction was investigated by adding 2, 4, 6, and 8mg / mL proteinase XIV to broccoli samples with selenium content of 0. 81mg / kg (calculated as Se). The effect of adding 6mL, 10mL, 12mL, and 15mL of Tris-HCl buffer solution on the extraction was compared. The extraction time of the samples also had a great influence on the extraction efficiency of the selenium speciation. The effects of four extraction times of 1h, 3h, 5h and 7h on the extraction were compared. RESULTS: The ZORBAX SB-Aq C18 separation system was used in this study because of the short analysis time and high sensitivity of each selenium speciation. Protease XIV was the most effective extraction reagent for selenium; therefore proteinase XIV was chosen as the extraction reagent. The concentration of selenium speciation increased with the concentration of proteinase XIV. The maximum concentration of selenium speciation was reached when the concentration of proteinase XIV was 6mg / mL. It was reported that the use of Tris-HCl buffer solution with proteinase XIV at appropriate pH conditions could further improve the extraction efficiency and maintain the stability of selenium speciation. The volume of Tris - HCl buffer increased, the extraction efficiency of each selenium speciation gradually increased and then decreased, and the final selection of Tris -HCl buffer solution addition was 12mL. A longer extraction time would help to increase the extraction effect, but too long an enzymatic digestion time would also cause a decrease in the stability of SeMet and SeCys2 . To ensure high extraction efficiency and reduce the conversion of selenium speciation, an extraction time of 3h was preferred. After optimization and selection, the final analysis method was determined as follows: weighing a certain amount of broccoli sample into 12mL of Tris-HCl (pH = 7. 4, containing 6mg / mL proteinase XIV) at a concentration of 100mmol / L, vortexing and mixing, and then sonicating at 37℃ for 3h. After centrifugation, the extraction were eluted with 10mmol / L citric acid and 5mmol / L sodium hexane sulfonate (pH = 4 with 1% methanol) on ZORBAX SB-Aq C18 reversed)phase column. ICP / MS was used for analysis and determination. This method can achieve effective separation and determination of five selenium speciation within 8 minutes. The linearity range of the method was 0. 3-100. 0μg / L, with linear correlation coefficients (r) greater than 0. 999. The detection limits of Se ( Ⅳ), Se ( Ⅵ), MeSeCys, and SeMet were within the range of 1. 2 - 6. 0μg / kg (calculated as Se). The standard recovery tests were carried out on broccoli samples at low, medium, and high concentration. The recoveries of these four selenium speciation, Se(Ⅵ), Se(Ⅳ), MeSeCys and SeMet, were 81. 9%-105. 3% with relative standard deviations (RSD) less than 5%. The method established in this study was used to determine SeMet in the EU-certified reference material (ERM BC210a, wheat flour), and the measured value of SeMet was within the range of its standard values. More than 20 commercially available broccoli samples collected from different regions of China were analyzed and determined. The results showed that the selenium speciation in commercially available broccoli was mainly MeSeCys, with small amounts of Se(Ⅵ), Se(Ⅳ), and SeMet, and also a small amount of unknown selenium-containing compounds was also present. Two problems identified in the methodological study were explored. (1) The effect of proteinase XIV dosage on the stability of SeCys2 was investigated by adding 1, 2, 4, and 6mg / mL of proteinase XIV to SeCys2 standard solution, respectively. The results showed that as the concentration of proteinase XIV increased, the signal value of SeCys2 gradually decreased and the signal value of three unknown peaks gradually increased. At the same time, the recovery of SeCys2 in broccoli samples decreased to 10%. Based on the above conditions, it is assumed that the content of proteinase XIV and the matrix of broccoli samples affect the stability of SeCys2 . (2) Three different broccoli samples were selected for Se(Ⅳ) standard recovery tests: fresh commercially available broccoli samples, freeze-dried powder of commercially available broccoli, and freeze -dried powder of broccoli fortified with Se(Ⅳ) selenium fertilizer. A certain amount of the above three samples was added with Se(Ⅳ) standard solution and 100mmol / L Tris -HCl ( pH = 7. 4, containing 6mg / mL of proteinase XIV). The determination was then carried out according to the proposed analytical method and the mean recoveries of the three samples were found to be 81. 1%, 69. 5% and 1. 53%, respectively. The Kruskal-Wallis rank sum test showed that the recoveries of Se ( Ⅳ) were significantly different among the three samples ( p < 0. 05 ). Previous investigations have found that phenolic substances can affect the stability of Se ( Ⅳ) and that the addition of selenium fertilizer during the growth of broccoli can change the phenolics. Based on the above, it is assumed that the presence of phenolics in broccoli samples may affect the determination of Se(IV). CONCLUSIONS: A method for the determination of Se(Ⅳ), Se(Ⅵ), MeSeCys, and SeMet in commercially available broccoli by HPLC - ICP - MS is established by selecting and optimizing the sample pretreatment and analytical conditions. The Tris - HCl buffer solution containing proteinase XIV is chosen for the extraction of samples. It is found that the stability of SeCys2 is affected by the concentration of proteinase XIV and broccoli samples matrix. It is hypothesized that the presence of large amounts of phenolics in the samples can affect the determination of Se(Ⅳ) for reasons to be further explored. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department 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.)

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.)

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.)

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology 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.)

Selenium (Se) is a trace element that plays a crucial role in human health. It has antioxidant, anti-cancer and anti-viral properties and is essential for a healthy body. The level of Se in the human body is largely dependent on daily dietary intake, which is in turn influenced by the amount of Se that enters the food chain from the soil. The global distribution of Se in soil is uneven, with a large difference in concentrations ranging mainly between 0. 01- 2. 0mg / kg. The average abundance of Se in the Earth’s crust is 0. 07mg / kg, but in some Se-enriched areas, it can reach up to 1200mg / kg. The chemical behavior of Se in soils is complex and diverse, involving processes such as adsorption - desorption, precipitation - dissolution, oxidation - reduction, methylation - demethylation and complexation reactions, each of which affects the bioavailable Se and is influenced and conditioned by factors such as soil pH, soil organic matter, metal oxides, clay and microorganisms. Roots are the primary site for most plants to absorb Se, which is then transported, metabolized, and accumulated. Plants can directly absorb Se from the soil, including Se that exists in the form of free ions, carbonate-bound Se, and Se adsorbed on the surfaces of clay and humus in soil solutions. However, selenite and selenate can be reduced to solid, insoluble Se(0) and metalSe precipitates that are not bioavailable in locally anaerobic areas (such as soil aggregates) or used by bacteria as terminal electron acceptors. Previous researchers have conducted a lot of work on chemical extraction methods, but there are still problems, such as insufficient extraction specificity and Se form transformation during the extraction process. Hence, an accurate approach for predicting the amount of soil Se that can be absorbed by plants is essential. However there are no clear paths for the choices of assessment methods and influencing factors of soil Se bioavailability. These problems have restricted the utilization of Se -enriched land resources. Thus, providing a scientific basis for the development and utilization of Se-enriched land resources is the goal here by summarizing the main assessment methods and dominant factors on soil Se bioavailability. Determining the activity of Se in soils comprehensively requires considering the complicated and varied effects of natural conditions on its bioavailability, which can be studied through characterization methods and identification of influencing factors. Therefore, it is of practical importance and a challenge to accurately determine the form of Se in soils and assess its bioavailability. Current methods for characterizing the bioavailability of soil Se include the traditional chemical extraction methods ( single extraction and sequential extraction) and the emerging Diffusive Gradients in Thin films (DGT) technique. Chemical extraction is a process that involves separating a specific component or substance from a mixture using a solvent or a chemical reagent. The extraction method depends on the physical and chemical properties of the substance being extracted and the nature of the mixture. The general steps involved in a chemical extraction method are: choosing the appropriate solvent or chemical reagent that can selectively dissolve the desired substance while leaving the unwanted components behind, mixing the mixture and the solvent / reagent together to allow the selective extraction of the desired substance, separating the extracted substance from the mixture using various techniques such as filtration, centrifugation, or evaporation, and purifying and isolating the extracted substance by further chemical or physical methods if necessary. The DGT technique is an effective environmental chemistry method used for identifying elements and compounds in various aqueous environments, including natural waters, sediments, and soils. This technique is particularly useful for detecting bioavailable trace elements, and it can be applied for in - situ detection. The DGT technique involves using a specially-designed passive sampler that comprises a binding gel, a diffusive gel, and a membrane filter. The element or compound of interest passes through the membrane filter and diffusive gel before being assimilated by the binding gel in a rate-controlled manner. Subsequently, the binding gel is analyzed post-deployment, enabling the determination of the time-weighted-average bulk solution concentration of the element or compound via a simple equation. The advantages and limitations of chemical extraction methods, DGT technique and bioavailability assessment models of Se at a regional scale are compared. Traditional chemical extraction procedures such as single extraction or sequential extraction can be used to characterize the bioavailability of Se in the soil, to a certain extent. Still, the extraction process has many limits and incomplete extraction problems. The DGT method can be used to simulate the root uptake process of plants and can better characterize the bioavailability of Se compared to sequential extraction. One of the major advantages of the DGT technique is its ability to provide accurate and reliable results, even at low concentrations. Additionally, this technique is non-destructive and can be used in-situ, making it suitable for real-time monitoring of environmental conditions. However, there are also some limitations associated with the DGT technique. For instance, the binding gel used in this method may not be specific to the target element or compound, leading to the possibility of cross-reactivity with other substances. Additionally, the technique may be influenced by factors such as temperature, pH, and ionic strength, which could affect the accuracy of the results. Using large-scale crop-root soil samples, a soil-crop Se assessment model was developed with parameters of physicochemical indicators ( e. g. soil pH, soil organic matter, soil Se, etc. ), which can better predict Se bioavailability on a regional scale. Some major and minor influencing factors affecting the uptake of Se in soil by plants are discussed. In short, topography and soil type, Se species, pH and organic matter are the main factors affecting bioavailable Se, with plant species and soil aging as secondary factors. In brief, the main limitations of the characterization methods for the bioavailability of different forms of Se are: a single extraction method can be affected by soil properties, soil / solution ratio, extraction time, the pH value of the extraction agent, and other factors. Sequential extraction methods have problems with incomplete extraction, dilution of the extract, and Se loss during centrifugation and filtration. These traditional methods cannot be used to reflect the dynamic processes of the solid - phase soil - solution - root system. DGT technology is a method that disturbs the equilibrium between soil solution and solid phase, simulating the dynamic process of Se uptake by roots, and has advantages in assessing bioavailability. However, it is still questionable whether it can be used to fully predict the replenishment dynamics of Se in field soil. The main factors affecting the bioavailability of soil Se are: (1) Topographical factors such as altitude, slope, and terrain wetness index, which have some influence on soil Se content; there are large differences in organic matter, iron / aluminum hydroxides, and pH among different soil types, which can be controlled to affect Se migration and bioavailability; (2) Soluble and exchangeable Se are more easily absorbed by plants, and selenate with better mobility is easier to absorb, transport, and metabolize in plants than selenite; (3) Increasing soil pH can generally improve Se bioavailability, but this is not the case in organic-enriched soils. Currently, there is no universally applicable method for evaluating soil Se bioavailability, as it is influenced by many factors such as topography, soil type, and soil physicochemical properties. This makes it difficult to compare and verify different results. Improving in-situ DGT analysis technology and modifying the analysis of Se forms are important technical means for accurately evaluating soil Se bioavailability and are also important directions for future development. [ABSTRACT FROM AUTHOR]

In order to study the calcium speciation characteristics in leaves of golden Camellia species under different habitats, 10 species of golden Camellia from calcareous soil habitats and four species from acidic soil habitats were used as the research objects. The calcium content(Soil-Ca)and pH(Soil-pH)of habitat soil, and the contents of calcium nitrate and calcium chloride(AIC-Ca), water soluble organic acid calcium(H2O-Ca), calcium pectate(NaCl-Ca), calcium phosphate and calcium carbonate(HAC-Ca), calcium oxalate(HCl-Ca), calcium silicate(Res-Ca), and total calcium(Tot-Ca)of leaves were measured. The results were as follows:(1)the Soil-Ca and Soil-pH of calcareous soil were extremely significantly(P<0.01)higher than those of acidic soil.(2)The leaf calcium speciation of golden Camellia species from calcareous soil habitats was primarily HCl-Ca(41.17%), while species from acidic soil habitats was primarily NaCl-Ca(43.10%), and all calcium speciation and total calcium content in leaves of species from calcareous soil were extremely significantly(P<0.01)higher than that from acidic soil except for AIC-Ca and NaCl-Ca.(3)Correlation analysis showed that most of the content of calcium speciation in leaves was extremely significantly(P<0.01)and positively correlated with Soil-Ca and Soil-pH, indicating that soil environment had an important influence on the leaf calcium speciation characteristics of golden Camellia species.(4)According to one-way ANOVA, the content of each leaf calcium speciation was extremely significant(P<0.01)difference among the species in golden Camellia revealing that the calcium speciation characteristics had a considerable variation during the species differentiation.(5)Cluster analysis based on calcium speciation characteristics showed that the 14 species of golden Camellia could be grouped into three categories. In summary, the differences in leaf calcium speciation of plants of golden Camellia species in different habitats may be the consequence of a combination of soil environmental and genetic factors. The results of this study will help to understand the adaptation mechanism of golden Camellia species to soil calcium and provide a reference for the formulation of conservation measures. [ABSTRACT FROM AUTHOR]

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Rare earth elements (REEs) are not only important strategic resources, but also have important research significance in tracing the sources of rocks, minerals, sediments, and other materials due to their unique geochemical properties. In recent years, with the increasing use of REEs in modern society, anthropogenic REEs have attracted widespread attention from scholars at home and abroad through different pathways into environmental media such as the atmosphere, water and soil. Gadolinium (Gd), one of the most widely used REEs, is commonly used as Gd - based constrast agents ( GBCAs). Since the application of GBCAs in the 1980s, their use has increased year by year. However, GBCAs are highly hydrophilic and stable, and they are difficult to remove in conventional wastewater treatment; the vast majority of them can directly enter urban and surrounding waters. Since Bau and Dulski first reported positive Gd anomalies in the Rhine River in Germany in 1996, anthropogenic Gd, an emerging contaminant, has now been detected in surface waters worldwide. However, there are relatively few studies on anthropogenic REEs, and the direct determination of them is difficult due to the constraints of detection techniques, and traditional methods for estimating anthropogenic REEs are inevitably subject to varying degrees of error. Since its introduction in the 1980s,inductively coupled plasma-mass spectrometry (ICP-MS) has shown great potential for trace multi-element analysis due to its high sensitivity, low detection limits and wide linearity range. The technique combines a plasma ion source with high ionization efficiency and a mass spectrometer with the advantages of high sensitivity, rapid multi-element detection and less mass interference compared to spectroscopy in a special interface, making it a highly efficient technique for simultaneous multi - element analysis. The development of high-precision ICP-MS and its coupling techniques, has led to a revolutionary breakthrough in the study of REEs provenance indication. The combination of highly selective separation techniques such as ion chromatography and highly sensitive ICP-MS has played an important role in the analysis of anthropogenic REEs, and the elemental speciation analysis capabilities of it make this one of the key research tools for the analysis of anthropogenic REEs. The progress of geochemical features of REEs such as isotopes in identifying material sources, resolving key processes and tracing environmental behavior, is summarized in this study, mainly including: ( 1 ) REEs fractionation patterns and isotopic features have been widely used in traditional provenance indication, and research is mainly based on REEs content or isotope information, combined with relevant mathematical and statistical models; (2) The speciation of REEs can provide an important basis for indicating anthropogenic activities, for example, due to the regional differences in the types of GBCAs used, there are obvious geographical differences in the speciation of anthropogenic REEs, with a high detection rate of macrocyclic GBCAs and a low detection rate of linear GBCAs in natural waters in regions such as Germany. On this basis, the application of ICP -MS and its coupling techniques in the source tracing of REEs is systematically reviewed, the main studies on REEs for tracing the sources of substances and indicating human activities are summarized, and the prospects for the development of source tracing of REEs are outlined. Among these analytical techniques, laser ablation multicollector inductively coupled plasma-mass spectrometry (LA-MC-ICP -MS) can be used to obtain in-situ information on the spatial distribution of the isotopic composition of REEs within samples. Hydrophilic interaction liquid chromatography coupled to inductively coupled plasma-mass spectrometry (HILIC-ICP-MS) has become an important tool for the analysis of the speciation of anthropogenic REEs in waters. To address the shortcomings of the current technical approach, a research outlook for the development of rapid and portable analytical techniques, the integration of multidimensional information for tracer studies, and the integrated consideration of the effects of human activitiesis proposed. It is worth noting that the frequency and concentration levels of anthropogenic REEs in the natural environment have increased significantly, which may affect the distribution characteristics of geogenic REEs and thus reduce the accuracy of traditional source tracing studies. Therefore, future studies need to consider whether human activities in the vicinity have significantly influenced the study area before conducting conventional provenance indication analyses. [ABSTRACT FROM AUTHOR]

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Copyright of Asian Journals of Ecotoxicology is the property of Gai Kan Bian Wei Hui 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: The development of urban industrialization causes soil heavy metal pollution and other environmental problems. Studies have shown that the damage caused by soil heavy metals to the ecological environment is not only related to the total content, but also depends on the speciation of heavy metals. OBJECTIVES: To investigate the content characteristics, speciation and risk status of heavy metals in soil of a city in the Hetao Plain. METHODS: 52 soil samples were collected from different functional areas of the Hetao Plain, heavy metals were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS), atomic fluorescence spectrometry (AFS) and other analytical methods to study the total content and speciation. The ecological risk of soil heavy metals was evaluated using the RAC risk assessment method. RESULTS: The results showed that the contents of heavy metal elements (except As) in surface soil were higher than the background values in the Hetao Plain, the variation coefficients of Pb, Cr, Mn, Cd and Zn were large and the spatial distribution was not uniform, which were significantly affected by human activities. The heavy metal content in the industrial area exceeded the background value, especially Cd (5.83 times of background value) and Pb (3.58 times of background value). Road heavy metal contents were also significantly higher than the background value, Cd was nearly 4 times the background value. Except for Cd in industrial areas, other heavy metals were mainly in residual fraction. The residual fractions of Cr, Ni, Cu and As were more than 70%. The residual fraction of Cd in each functional region accounted for about 30%. RAC risk assessment results showed that Cd and Pb in industrial areas reached the high-risk level. CONCLUSIONS: The research results provide scientific basis for identifying the potential environmental risks in urban area soil and proposing effective prevention. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group 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.)

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.)

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BACKGROUND: Heavy metal pollution in soil has been a serious threat to human health and ecological environmental safety. Stabilization remediation has become an important means of remediation of heavy metal contaminated soil due to the high efficiency and low cost. Attapulgite modified by alkali with an improved performance, provides an important basis for its stabilization and remediation of heavy metal contaminated soil. OBJECTIVES: To analyze the changes in physical and chemical properties of attapulgite before and after modification, and to study the effects of attapulgite modified by NaOH on the chemical speciation changes and environmental risks of Cd in contaminated soil, and to explore the stabilization effects of attapulgite modified by NaOH on Cd in the soil. METHODS: Different proportions of NaOH were used to modify attapulgite. The surface characteristics, crystal structure and functional groups of the materials were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Stabilization experiments were carried out on artificially prepared heavy metal Cd contaminated soil to study the effects of NaOH-modified attapulgite on the changes of chemical speciation of Cd and environmental risks in contaminated soil. RESULTS: By adding the modified material with the mass ratio of NaOH to attapulgite of 1∶2, the pH value of the soil was significantly increased by 0.85 units. The exchangeable Cd content decreased by 46.28% and the residual Cd content increased by 1.98 times. The risk assessment code (RAC) and potential risk index (PRI) of Cd in soil decreased the most from 36.70% and 207.90 to 20.08% and 86.40, respectively, which effectively reduced the transfer capacity and environmental risk of Cd in soil. According to SEM, XRD and FTIR analyses, after modification, the surface roughness of attapulgite increased, chemical bonds such as Si—O—Si bonds were opened, so active sites for adsorption of heavy metals increased. Attapulgite modified by alkali immobilized Cd mainly through adsorption, and the reaction of silanol and hydroxide with Cd2+ generated precipitate, so as to achieve the effect of stabilizing and repairing Cd contaminated soil. CONCLUSIONS: Alkali-modified attapulgite can effectively stabilize Cd in soil, which has a significant application prospect in remediation of heavy metal contaminated soil. [ABSTRACT FROM AUTHOR]

The speciation of heavy metals in soil is an important factor determining their bioavailability and toxicity, and it is crucial for the scientific assessment of ecological risks posed by heavy metals in soils of typical carbonate areas with high geological background in southwest China. In order to investigate the distribution of speciation of heavy metals in soils of carbonate rock with high geological background, we selected a typical carbonate rock distribution area in Guizhou Province and used the second national soil survey plots as sampling units. A total of 309 topsoil samples were collected from farmland. The improved Tessier seven-step sequential extraction method was used to analyze the seven chemical forms of heavy metals:water-soluble (F1); exchangeable (F2); carbonate-bound (F3); weakly organic-bound (F4); iron-manganese oxide-bound (F5); strongly organic-bound (F6); and residual (F7) forms of arsenic (As), cadmium (Cd), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn). The study found that the residual forms of heavy metals As, Cu, Hg, Ni, Pb, and Zn in the soil accounted for more than 50%, the effective components (F1-F3) accounted for less than 5%, and the potential biological effective components (F4-F6) were less than 45%, indicating low reactivity and low ecological risk. The effective and potentially bioavailable components of Cd accounted for 55.49% and 29.37%, respectively, which were much higher than those of other heavy metals. The ecological risk based on the speciation of heavy metals in the soil was much lower than that based on the total content of heavy metals. The stepwise regression equations could effectively establish the relationship between the bioavailable and potentially bioavailable fractions of Cd, Cu, and Pb and their influencing factors. Total heavy metal contents and pH value were important factors influencing the speciation of heavy metals in soils of carbonate rock with high geological background areas. The enrichment of heavy metal elements in the residual fraction was influenced by long-term zinc smelting activities and the weathering of carbonate rocks into soil. Soil organic matter (OM) and oxide content had a relatively small influence on the speciation of heavy metals in the soil.

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Copyright of Research of Environmental Sciences is the property of Research of Environmental Sciences 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.)

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Copyright of Journal of Southern Agriculture is the property of Journal of Southern Agriculture 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.)

To control of phosphorus release from soil after farmland inundation around the lake and reservoir， calcium modified biochar （Ca-BC） was prepared using the coprecipitation method. Through X-ray photoelectron spectroscopy （XPS）， X-ray polycrystalline powder diffraction （XRD）， adsorption experiments， and simulated culture experiments， the effects of Ca-based biochar on the fraction of soil phosphorus （P） and its stabilization mechanism were studied. The results showed that the adsorption process of Ca-based modified biochar conformed to Langmuir （ R 2 = 0.940） and the first-order adsorption kinetic model （ R 2 = 0.961）， indicating that the P adsorption was a single-layer adsorption dominated by chemical action， and the maximum adsorption capacity was 267.93 mg·g -1 . The simulated culture experiment indicated that when the modified biochar was 1%， the exchangeable fraction of phosphorus in the soil decreased from 7.42% to 4.59%. The XRD results demonstrated that Ca 3 （PO 4 ） 2 and hydroxyapatite absorption peaks appeared after adsorbed phosphorus on biochar， which proved that phosphate formed a relatively stable crystal precipitation. As shown in the XPS spectrum analysis， the carbonyl functional groups participated in the phosphorus fixation process， which improved the adsorption capacity of biochar for phosphorus. In general， when the concentration of Ca-based modified biochar was greater than 1%， it had a good fixation capacity for phosphorus release and had potential application value for controlling phosphorus release in soil.

[Objective] Correlations between contents of heavy metals and sediments properties were analyzed. Speciation character and the bioavailability of heavy metals were discussed based on the rations secondary phase and primary phase(RSP) and potential ecological risk assessment. [Method]Taking the mangrove wetland sediments of Qinglan Harbor wetland in Hainan as the research object, speciation and contents of four heavy metals(Cu, Zn, Cd and Pb)in sediments of mangrove wetland were treated by BCR sequential extraction procedure. [Result] Between heavy metals it had different degrees of correlation and exhibited significantly positive correlation between Cd and Pb, suggesting that the pollution of Cd and Pb resulted from homologous pollutants. Cu and Cd were mainly in the acid soluble-extractable fraction;Pb was mainly in the reducible fraction;Zn was dominated by residual fraction;It showed that Cu, Cd and Zn in the sediments of the study area had serious potential hazards. There was significant correlation between the forms of Cd, Cu, Zn and PB of heavy metals in sediments. Contents of Cu and Cd existed as weak acid soluble fraction and oxide fraction exhibits significantly positive correlation with pH, indicating that sediments pH had a certain impact on chemical speciation of heavy metals. [Conclusion] These 4 kinds of heavy metals in the sediments have high bioactive state, and have strong biological activity, which are easy to be absorbed and used by plants. Cd, Cu, Zn and Pb have higher risk of release in the sediments of the research area, which should be paid enough attention. [ABSTRACT FROM AUTHOR]

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Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department 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.)

A complete combination experimental design was conducted to compare the effect of five organic manures under different dosages, including nutshell manure(NM), pig manure(PM), sludge manure(SM), humus manure(HM)and earthworm manure(EM), on the availability of lead(Pb)in soils with different levels of Pb(adjusted by addition of exogenous Pb as(CH3COOH)2 Pb solution), and the relationships between Pb availability and its chemical speciation in soils were also discussed. The results showed that the addition of organic manures reduced the contents of available Pb in soils with mild, moderate, and severe pollution of Pb, and the decline degree increased with increase of amount of organic manures which was particularly obvious in soil with moderate and severe contaminated Pb. SM and PM treatment showed the most prominent effects among the five organic fertilizer where the available Pb contents in soils were respectively decreased by 24.22%~36.10% and 19.33%~35.48% as compared with the control group. After adding organic manures, the change trends of contents of available Pb in soils with time showed increase firstly and then decrease until a peak value achieved in 10 days, following with gradual decline and finally approaching the stability in 60 days. The dynamics of Pb availability variation were consistent with the dynamics of Pb chemical speciation. After the treatment of organic manures, the contents of carbonates bond Pb(Carb-Pb)decreased by 5.36%~ 12.91% while those bounded by organic matter(OM-Pb)increased slightly, and those of residual Pb(Res-Pb)increased significantly by 18.92%~45.47%, for mild contaminated soil; For moderate contaminated soil, the contents of Carb-Pb slightly decreased while those of Res- Pb substantially increased by 24.30%~38.04%; For severe contaminated soil, the contents of Carb-Pb did not change significantly, and those of OM-Pb and Res-Pb increased apparently, raised by 14.46%~41.06% and 29.02 %~56.29% respectively. The Carb-Pb had a significant positive contribution to available Pb in soil, while OM-Pb and Res-Pb demonstrated obvious negative contributions. The organic manures reduced significantly the availability of Pb in soil mainly by decreasing the contents of Carb-Pb and increasing those of OM-Pb and Res-Pb. [ABSTRACT FROM AUTHOR]

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Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology 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.)

In this review, we summarized the uptake, translocation and metabolism mechanisms of selenium (Se) in plants. Water-soluble Se, including selenate, selenite and some organic selenium, was the predominant form taken up by plants. The active uptake of selenate in plant could be mediated by high affinity sulfate transporters. The mechanism of selenite uptake was not well understood, however, recent studies suggested that selenite uptake was probably mediated by Pi transporters. The translocation of Se from root to shoot was dependent on the form of Se supplied. The selenate taken up by plants was readily translocated to the shoots and reduced to selenite in leaves, then converted to organic Se compound. By contrast, most of the selenite taken up by plants in the roots and only a small fraction was translocated to the shoots. Se could be assimilated to seleno amino acids or selenoprotein after plant uptake, and then involved in the metabolism of plants. [ABSTRACT FROM AUTHOR]

The morphological characteristics of Cd, Cr, Cu, Ni, Pb, and Zn in sediments were analyzed using an improved BCR extraction method in four water types of Baiyangdian Lake:watercourse, trench, lake surface, and fish pond. The potential ecological risk index, secondary and primary phases, and risk assessment codes were used to systematically assess the pollution level and ecological risk of heavy metals in surface sediments. The results showed that:① the mean contents of heavy metals Cd, Cu, and Zn in the sediments were 0.37, 28.49, and 83.08 mg·kg -1 , respectively, 94.91%, 73.91%, and 46.39% of which exceeded the soil background value. ② Cd was dominated by the non-residual fraction (F1+F2+F3) with a fraction ranging from 54% to 97%, whereas Cr was dominated by the residual fraction (F4) with a mass fraction ranging from 87% to 99%. Cu, Ni, Pb, and Zn were mainly in the fraction of residual fraction. In the non-residual fraction, Cu and Ni were mainly in the oxidizable fraction (F3) state, whereas Pb and Zn were mainly in the reducible fraction (F2) state. ③ The RAC risk assessment results showed that there were 68.97%, 39.89%, 54.84%, and 49.78% points in channel, trench, open water, and fish pond samples, respectively, of Cd at high risk. The Cu, Ni, and Pb were at low risk. In general, the overall heavy metal pollution level in Baiyangdian Lake was low, but Cd had ecological risk and high bioavailability in the Fuhe River of the Nanliuzhuang area and the Baigouyin River.

Totally 126 samples of windowsill dust were collected from different floors along elevated road in Changzhou. The concentrations of Cu, Zn, Pb, Cd, Ni and Cr were determined, and the vertical distribution and chemical speciation were analyzed. The enrichment factor, bioaccessiblity, potential ecological risk and health risk were evaluated. The results showed that the average contents of Cu, Zn, Pb, Cd, Ni and Cu were 181.95, 709.99, 211.24, 2.76, 101.59 and 257.55 mg·kg -1 respectively, which were all higher than the background value. The enrichment factor of Cd was 33.05, with enrichment degree of strongly enriched. The enrichment degrees of Cu, Pb and Zn were all significantly enriched. These four heavy metals may come not only from transportation source, but also from natural source and regional industrial polluted gas. The enrichment factors of Ni and Cr were low, which may result from natural source. With the elevation of house height, the concentration of Cd increased, the concentrations of Pb and Zn increased first and then decreased, while Cu showed no significant differences. Zn, Cd, Cu and Pb mainly existed in the active form, while Ni and Cr mainly existed in the residual form. The bioaccessiblity of Zn and Cd was high, while that of other heavy metals was low. The modified potential ecology risk evaluation results showed that the risk of Cd was extremely high, and contributed mainly to the potential risk index of multi-element. The Cd from the windowsill of high height showed higher potential ecological risk. The carcinogenic risk of Cr to children was higher than the threshold value, while the carcinogenic risk and non-carcinogenic risk of other metals to children and adults were all below the safety thresholds.

In order to investigate the pollution characteristics of vanadium in sediments of the Three Gorges Reservoir (TGR), 67 sediment samples were collected from the section between Chongqing to Yichang in TGR. The concentration and chemical speciation of vanadium were measured and the spatial distribution of vanadium was discussed. Current pollution level of vanadium in TGR sediments was assessed by index of geoaccumulation and Häkanson ecological risk index. The results showed that:1the range of vanadium concentrations in TGR was 89.4-175.2 mg·kg -1 and the average concentration was 123.7 mg·kg -1 , which was slightly higher than the background value in sediments of Yangtze River. 2the spatial distribution of vanadium in TGR sediments showed that vanadium concentrations in the mainstream of TGR were higher than those in tributaries and the vanadium contents in the sediments in downstream were higher than those in upstream in term of the mainstream of TGR. 3highest vanadium concentration was found in the sediment in a developed county, indicating that this high level of vanadium concentration was attributed to anthropogenic input. 4chemical forms of vanadium in sediments were mainly in residual state (80%-89%, mass fraction), which had a significant positive correlation with total concentrations in sediments. 5vanadium contamination degree and potential environmental risk in TGR sediments were weak.