利用高能液相色谱测定根际分泌物中的有机酸: Ⅲ.干扰因子的影响

Methods for determining niene low molecular-weight oragnic acids in root exudates were developed by using reversed-phase high performance liquied chromatography with UV (ultraviolet) detection at 214 nm. The mobile phase was 18 mmol L^-1 kH2PO4 adjusted to pH 2.25 with phosporic acid nd the flow rate was 0.3 mL min^-1,The analytical column was a reversed-phase silica based C-18 column( shim-pack CLC-ODS).The root exudates were collected through submerging the whole root system into aerated deionized water for 2 hours ,The filtered exudate solutions were concentrated to dryness by rotary evaporation at 40℃,dissolved in 10 mL mobile phase.The chromatoraphic conditions of organic acid determination were analyzed.The results showed that there was a high selectivity and sensitivity in the organic acid determination by reversed-phase high performance liquid chromatography.Coefficients of variation for organic acied determination were lower than 10% except lactic acid .The recoveries were consistently between 80.1% to 108.3% .Detection limits were approximately 0.05 to 4.5 mg L^-1 for organic acids except succinic acid with the detection limit of 7.0 mg L^-1 .Phosphorus deficiency may contribute to the release of organic acids in soybean root exudates especially malic,lactic and citric acids.     

利用高能液相色谱测定根际分泌物中的有机酸: Ⅲ.干扰因子的影响

A solution culture experiment was conducted to investigate the effects of collection time and interfering ions on separation and determination of low-molecular-weight organic acids in root exudates of soybean using the method for directly collecting root exudates.The suitable cooection time of root exudates and the interferiung ions affecting organic acid determination were determined.The method for removing the interfering ions was established and analyzed.The release amount of root exudates increased with the increase of collection time from 0 to 120min but decreased with increasing of collection time from 120to 240min.The maximum exuding amounts of organic acids were observed in root exudates at the collection time of 120min.There was a significant difference of organic acid components between the treatments of collection time of 120min and 240min,Citric acid was founnd only in the treatment of 120min collection time,NO3^- was the main interfering ion in organic acid determination and had the same retention time as oxalic acid.Anion exchange resin(SAX)properly treated by HPLC(high performance liquid chromatography)solvent could remove NO3^- anion in sample solution of root exudates,thus enhancing the recoveries of organic acids in root exudates.There was no significant effect of the chemicals added into sample solution such as H3PO4,SAX and KNO3 on the retention time of organic acids.     

土壤温度系中瞬时现象重要性研究

The primary objective of this study was to investigate the impact of observation scale on the estimation of soil thermal properties. Transients are usually filtered out and ignored when classical Fourier approaches are used to deconstruct and model temperature time series. It was hypothesized that examination of such transients may be more important in identifying and quantifying short-term perturbations in internal soil heat transfer induced by agronomic disturbances. Data-logged temperatures were collected at 10-minute intervals from thermistor probes installed at 10 and 25 cm depths in isolated areas of two grassed plots. One plot （6T） had been treated twice with 6 Mg ha^-1 composted turkey litter as received. The other plot （NPK） was fertilized at the same time with NPK fertilizer. Various methods were used to analyze the series to obtain apparent soil thermal diffusivity （D-value） at various time scales. Results supported the hypothesis that short-term differences in internal soil heat transfer between the 6T and NPK plots were more manifest and effectively captured by estimated D-values calculated from the monthly and daily partial series. The 6T plot had higher soil organic matter content than the NPK plot and had lower apparent soil thermal diffusivity. Diurnal soil temperature amplitudes, required to calculate the mean D-values from partial series, were more effectively obtained using a temperature change rate method. The more commonly used Fourier analysis tended to be effective for this purpose when the partial series reasonably presented well-defined diurnal patterns of increasing and decreasing temperatures.     

利用烧失量方法精确测定土壤有机质

Wet oxidation procedure,i.e.,Walkley-Black (WB) method,is a routine,relatively accurate,and popular method for the determination of soil organic matter (SOM) but it is time-consuming,costly and also has a high potential to cause environmental pollution because of disposal of chromium and strong acids used in this analysis.Therefore,loss-on-ignition (LOI) procedure,a simple and cheap method for SOM estimation,which also avoids chromic acid wastes,deserves more attention.The aims of this research were to study the statistical relationships between SOM determined with the LOI (SOMLOI) and WB (SOMWB) methods to compare the spatial variability of SOM in two major plains,Shahrekord and Koohrang plains,of Chaharmahal-va-Bakhtiari Province,Iran.Fifty surface soil samples (0-25 cm) were randomly collected in each plain to determine SOM using the WB method and the LOI procedure at 300,360,400,500 and 550 ℃ for 2 h.The samples covered wide ranges of soil texture and calcium carbonate equivalent (CCE).The general linear form of the regression equation was calculated to estimate SOM LOI from SOM obtained by the WB method for both overall samples and individual plains.Forty soil samples were also randomly selected to compare the SOM and CCE before and after ignition at each temperature.Overall accuracy of the continuous maps generated for the LOI and WB methods was considered to determine the accordance of two procedures.Results showed a significant positive linear relationship between SOM LOI and SOM WB.Coefficients of determination (R2) of the equations for individual plains were higher than that of the overall equation.Coefficients of determination and line slopes decreased and root mean square error (RMSE) increased with increasing ignition temperature,which may be due to the mineral structural water loss and destruction of carbonates at higher temperatures.A temperature around 360 ℃ was identified as optimum as it burnt most organic carbon,destroyed less inorganic carbon,caused less clay structural water loss,and used less electrical energy.Although the trends of SOM in the kriged maps by the two procedures accorded well,low overall accuracy was observed for the maps obtained by the two methods.While not suitable for determination where high accuracy is required,determination of organic carbon through LOI is likely suitable for exploratory soil surveys where rough estimation of organic matter is required.     

配位体交换在减慢由酸雨造成的可变电荷土壤酸化速度中的意义

For the purpose of evaluating the role of ligand exchange of sulfate ions in retarding the rate of acidification of variable charge soils,the changes in pH after the addition of different amounts of HNO3 or H2SO4 to representative soils of China were measured .A difference between pH changes caused by the two kinds of acids was observed only for variable charge soils and kaolinite,but not for constant charge soils and bentonite,The larger the proportion of H2SO4 in the HNO3-H2SO4 mixture,the lower the calculated H^ ion activities remained in the suspension.The difference in H^ ion activities between H2SO4 systems and HNO3 systems was larger for soils with a low base-saturation(BS) percentage than those with a high BS percentage.The removal of free iron oxides from the soil led to a decrease in the difference,while the coating of Fe2O3 on a bentonite resulted in a remarkable appearance of the difference.The effect of ligand exchange on the acidity status of the soil varied with the soil type.Surface soils with a high organic matter content showed a less pronounced effect of ligand exchange than subsoils did.It was estimated that when acid rain chiefly containing H2SO4 was deposited on variable charge soils the acidification rate might be slower by 20%-40% than that when the acid rain chiefly contained HNO3 for soils with a high organic matter content,and that the rate might be half of that caused by HNO3 for soils with a low organic matter content,especially for latosols.     

有机物质对土壤溶液中铜形态的影响

Incubation of two soils,a red soil derived from granodiorte and a fluvo-aquic soil from alluvial deposit,with rice straw,Chinese milk vetch and pig manure under submerged condition were conducted to study the species of Cu in soil solutions as affected by the organic materials.The organic materials increased total soluble Cu by raising dissolved organic carbon(DOC) in soil solution when the solution pH values were below the range in which Cu deposited quickly.When the solution pH rose to this rage,the increase of DOC did not raise total soluble Cu.Total soluble Cu in all the treatments dropped with incubation time.After adding organic materials labile Cu dropped with incubation time and decreased sharply in the pH range of Cu precipitation.Addition of organic materials enhanced slowly labile Cu but depressed the ratio of labile Cu to total soluble Cu.Slowly labile Cu decreased with incubation time.Sepwise multiple linear regression analysis showed that total soluble Cu was positively correlated with Eh and DOC(P=0.0025),labile Cu was negatively correlated with pH(P=0.0118),and slowly labile Cu was positively correlated with Eh and DOC(P=0.0022).Both the labile and slowly labile Cu were correlated with total soluble Cu at extremely significant levels.     

缺锌和高锌胁迫下苹果根系有机酸对锌的内稳性的响应

To elucidate the mechanisms of tolerance to zinc (Zn) deficiency and Zn toxicity in the root of apple trees, the apple rootstock Malus hupehensis (Pamp.) Rehd seedlings were selected to study the responses of organic acids to Zn homeostasis in roots under low Zn (0 μmol L-1 ), adequate Zn (as control, 4 μmol L-1 ) and toxic Zn (100 μmol L-1 ) treatments. The differences of Zn concentrations and accumulations in the roots were highest, compared with those in the stems and leaves, when apple seedlings were subjected to low and toxic Zn treatments for 1 d. The concentrations and accumulations of oxalic and malic acids in the roots in the low and toxic Zn treatments increased by 20% to 60% compared with those of the control treatment. Significantly negative correlations were found between the total Zn concentrations and the concentrations of oxalic and malic acids in the roots under 1 d of low Zn treatment. However, contrary correlations were found for the toxic Zn treatment. Meanwhile, the maximum influx rates of Zn 2+ under low and toxic Zn treatments increased by 30% and 20%, respectively, compared with the rate of the control treatment. Both Zn deficiency and Zn toxicity increased the concentrations of organic acids in root after short-time Zn treatment, which could resist Zn stress through balanding Zn homeostasis in M. hupehensis Rehd.     

有机酸对高岭石, 针铁矿和水铝英石吸附镉的影响

Effects of organic acids （oxalic, acetic, and citric） on adsorption characteristics of Cadmium （Cd） on soil clay minerals （kaolinite, goethite, and bayerite） were studied under different concentrations and different pH values. Although the types of organic acids and minerals were different, the effects of the organic acids on the adsorption of Cd on the minerals were similar, i.e., the amount of adsorbed Cd with an initial solution pH of 5.0 and initial Cd concentration of 35 mg L^-1 increased with increasing concentration of the organic acid in solution at lower concentrations, and decreased at higher concentrations. The percentage of Cd adsorbed on the minerals in the presence of the organic acids increased considerably with increasing pH of the solution. Meanwhile, different Cd adsorption in the presence of the organic acids, due to different properties on both organic acids and clay minerals, on kaolinite, goethite, or bayerite for different pHs or organic acid concentrations was found.     

蔬菜连作对铜尾矿土壤中有机碳、腐殖质碳以及可溶性有机碳的影响

Carbon of humus acids （HSAC） and dissolved organic carbon （DOC） are the most active forms of soil organic carbon （SOC） and play an important role in global carbon recycling. We investigated the concentrations of HSAC, water-soluble organic carbon （WSOC）, hot water-extractable organic carbon （HWOC） and SOC in soils under different vegetation types of four copper mine tailings sites with differing vegetation succession time periods in Tongling, China. The concentrations of HSAC, WSOC, HWOC and SOC increased with vegetation succession. WSOC concentration increased with the accumulation of SOC in the tailings, and a linearly positive correlation existed between the concentrations of HSAC and SOC in the tailings. However, the percentages of HSAC and DOC in the SOC decreased during vegetation succession. The rate of SOC accumulation was higher when the succession time was longer than 20 years, whereas the speeds of soil organic matter （SOM） decomposition and humification were slow, and the concentrations of HSAC and DOC increased slowly in the tailings. The percentage of carbon of humic acid （HAC） in HSAC increased with vegetation succession, and the values of humification index （HI）, HAC/carbon of fulvic acid, also increased with the accumulation of HSAC and SOC in soils of the tailings sites. However, the HI value in the each of the tailings was less than 0.50. The humification rate of SOM was lower than the accumulation rate of SOM, and the level of soil fertility was still very low in the tailings even after 40 years of natural restoration.     

Fractionation and distribution of selenium in soils

Abstract

A modified selenium (Se) fractionation procedure was used to study Se distribution in three soils (two silt loams and one silty clay). This sequential procedure consisted of: i) 0.2 M potassium sulfate (K₂SO₄)‐soluble fraction, ii) 0.1 M potassium dihydrogen phosphate (KH₂PO₄)‐exchangeable fraction, iii) 0.5 M ammonium hydroxide (NH₃H₂O)‐soluble fraction, iv) 6 M hydrochloric acid (HCl)‐extractable fraction, and v) residual fraction digested with perchloric (HClO₄) and sulfuric (H₂SO₄) acids. The fractionation procedure had high recovery rates (92.5 to 106%). The Se distribution in soil was controlled by soil properties, such as pH, oxide, clay, and calcium carbonate (CaCO₃) contents. In the untreated soil samples, residual Se fraction was dominant. In the Se‐enriched soils, the silty clay had significantly more Se in the NH₃H₂O and residual fractions while in the two silt loams the largest were KH₂PO₄ and residual fractions. The Se availability in the two silt loams was higher than in the silty clay. The Se availability pattern in the untreated soils was: unavailable (HCl + residual fractions) >> potentially available (KH₂PO₄ + NH₃H₂O fractions) > available (K₂SO₄ fraction), while in the Se‐enriched soils it was potentially available > unavailable > available.     

Comparison of different extractants for the determination of inorganic sulphate in gypsum‐free agricultural soils

Four frequently used extractants (H₂O, 0.1 M NaCl, 0.016 M KH₂PO₄, and 0.5 M NaHCO₃) as well as different extraction conditions have been tested for sulphate extraction from gypsum‐free agricultural soils. Water is the preferable extractant for soils with pH > 6. Two extraction steps have to be carried out for complete extraction (> 95%). A 0.016 M KH₂PO₄ solution was found to be the most efficient extractant for soils with a pH < 6 within a single extraction step. A shaking frequency of 170 min^‐1 and a duration of extraction of 4 hours are the optimized conditions for the sulphate extraction with H₂O and KH₂PO₄ solution.     

Evaluation of available boron content using eight methods of extraction in different soils from Córdoba and sucre in Colombia

The aim was to evaluate eight methods of boron (B) extraction in different soils from Córdoba and Sucre, Colombia. 37 samples were collected at a depth of 0–20 cm and carried to Soil and Water Laboratory of University of Córdoba for its chemical characterization. The available boron was extracted with the following methods: modified hot water, calcium chloride (CaCl₂) 0.05, hydrochloric acid (HCl) 0.05, barium chloride (BaCl₂) 0.006, manitol 0.05 + CaCl₂ 0.01, Ca(H₂PO₄)₂H₂O 0.008 in mol L^?1, mehlich-1 and ammonium acetate (NH₄OAc) (1.0 mol L^?1, pH = 7.0). The major quantity of boron was extracted with mehlich-1, HCl 0.05 mol L^?1 and hot water, extracting 0.36, 0.29 and 0.26 mg kg^?1, respectively. The extracting solution that correlated with the hot water method was HCl 0.05 mol L^?1 (r = 0.81); followed by Ca(H₂PO₄)₂H₂O 0.008 mol L^?1 (r = 0.62) and mehlich-1 (r = 0.54). According to characteristic and heterogeneity of soils, we recommend HCl method to extract available boron.     

Short‐Term Effect of Lime,Phosphorus, and Iron Amendments on Water‐Extractable Lead and Arsenic in Orchard Soils

Abstract

Lead arsenate was extensively used to control insects in apple and plum orchards in the 1900s. Continuous use of lead arsenate resulted in elevated soil levels of lead (Pb) and arsenic (As). There are concerns that As and Pb will become solubilized upon a change in land use. In situ chemical stabilization practices, such as the use of phosphate‐phosphorus (P), have been investigated as a possible method for reducing the solubility, mobility, and potential toxicity of Pb and As in these soils. The objective of this study was to determine the effectiveness of calcium carbonate (lime), P, and iron (Fe) amendments in reducing the solubility of As and Pb in lead‐arsenate‐treated soils over time. Under controlled conditions, two orchard soils, Thurmont loam (Hapludults) and Burch loam (Haploxerolls), were amended with reagent‐grade calcium carbonate (CaCO₃), iron hydroxide [Fe(OH)₃], and potassium phosphate (KH₂PO₄) and incubated for 16 weeks at 26°C. The experimental results suggested that the inorganic P increased competitive sorption between H₂PO₄ ^? and dihydrogen arsenate (H₂AsO₄ ^?), resulting in greater desorption of As in both Thurmont and Burch soils. Therefore, addition of lime, potassium phosphate, and Fe to lead‐arsenate‐contaminated soils could increase the risk of loss of soluble As and Pb from surface soil and potentially increase these metal species in runoff and movement to groundwater.     

EXOGENOUS APPLICATION OF POTASSIUM DIHYDROGEN PHOSPHATE CAN ALLEVIATE THE ADVERSE EFFECTS OF SALT STRESS ON SUNFLOWER

A greenhouse experiment was conducted to examine whether foliarly applied potassium + phosphorus (K + P) in the form of monopotassium phosphate (KH₂PO₄) could mitigate the adverse effects of salt stress on sunflower plants. There were two levels of root-applied salt [0 and 150 mM of sodium chloride (NaCl)], and varying levels of KH₂PO₄ [(NS (no spray), WS (spray of water), 5 + 4, 10 + 8, 15 + 12, and 20 + 16 mg g^?1 K + P, pH 6.5] applied foliarly to 18-day old non-stressed and salt stressed sunflower plants. Salt stress adversely affected the growth, yield, photosynthetic capacity, and accumulation of mineral nutrients in the sunflower plants. However, varying levels of foliar applied KH₂PO₄ proved to be effective in improving growth and yield of sunflower under salt stress. The KH₂PO₄ induced growth in sunflower was found to be associated with enhanced photosynthetic capacity, water use efficiency and relative water contents.     

Extractability and dissolution kinetics of pure and soil-added synthesized aluminium hydroxy sulphate minerals

Various extractants used in current analytical procedures for the fractionation of sulphur (S) in soils were compared with respect to their ability to dissolve Al hydroxy sulphate minerals of defined composition (basaluminite, K alunite, mixtures of basaluminite and Na alunite). The minerals were synthesized and aged in the laboratory at 20°C and 50°C. The dissolution kinetics at 20°C of these Al hydroxy sulphates in deionized water, 0.02M HCl and 0.02M NaOH were also investigated. The dissolution stability of the Al hydroxy sulphate minerals increased in the order basaluminite < K alunite < Na alunite. The dissolving power of the reagents used increased in the order H₂O ≤ 0.016M KH₂PO₄? 0.02M HCl ≈ acidic NH₄ oxalate ≈ 0.5M NaHCO₃ < Na₂ CO₃/NaHCO₃ < 0.1M NH₄F < 0.5M NH₄F < 0.05M NaOH ≤ 0.05M LiOH. In Al hydroxy sulphate-containing soils, inorganic S is probably understimated and ester sulphate S overestimated, if the inorganic S pool is assessed by extraction with KH₂PO₄, Ca(H₂PO₄)₂ or NaHCO₃ solutions. The dissolution of all studied Al hydroxy sulphates, particularly that of K and Na alunite, in H₂O and 0.02 M HCl is strongly delayed by kinetic restraints. Thus it seems unlikely that Al³⁺ or SO^2?₄ activites in soil solutions are strictly regulated by precipitation/dissolution equilibria of these minerals except for horizons with extraordinarily slow seepage water movement.     

Sorption of Phosphorus from Swine,Dairy, and Poultry Manures

In most phosphorus (P) sorption studies, P is added as an inorganic salt to a predefined background solution such as calcium chloride (CaCl₂) or potassium chloride (KCl); however, in many regions, the application of P to agricultural fields is in the form of animal manure. The purpose of this study, therefore, was to compare the sorption behavior of dissolved reactive P (DRP) in monopotassium phosphate (KH₂PO₄)–amended CaCl₂ and KCl solutions with sorption behavior of DRP in three different animal manure extracts. Phosphorus single‐point isotherms (PSI) were conducted on eight soils with the following solutions: KH₂PO₄‐amended 0.01 M CaCl₂ solution, KH₂PO₄‐amended 0.03 M KCl solution, water‐extracted dairy manure, water‐extracted poultry litter, and swine lagoon effluent. The PSI values for the dairy manure extract were significantly lower than the CaCl₂ solution for all eight soils and lower than the KCl solution for six soils. The PSI values were significantly higher, on the other hand, for poultry litter extract and swine effluent than the inorganic solutions in four and five of the soils, respectively. Our observations that the sorption of DRP in manure solutions differs significantly from that of KH₂PO₄‐amended CaCl₂ and KCl solutions indicates that manure application rates based on sorption data collected from inorganic P salt experiments may be inaccurate.     

Ammonium fluoride extraction for determining inorganic sulphur in acid forest soils

Current methods for determining inorganic sulphur (S) in aerated mineral soil horizons often result in underestimates. To overcome this defect we developed a new method combining a batch extraction with 0.5 m NH₄F solution at a soil:solution ratio of 1:5 with a subsequent analysis of the mobilized SO₄^2– by ion chromatography. The ammonium fluoride extraction enables us to characterize inorganic sulphate in non‐calcareous forest soils. It is more efficient than conventional procedures in which inorganic S is extracted with phosphate or bicarbonate solution. In contrast to the extraction with strongly alkaline reagents (NaOH, KOH, LiOH), the NH₄⁺–NH₃ buffer system in NH₄F prevents the pH of the suspension from exceeding 9.0 and thus the undesired conversion of organic S into SO₄^2– by auto‐oxidation and hydrolysis of ester sulphate. In a comparison we demonstrated that the inorganic S in six German forest soils is underestimated by up to 50% or 200 kg S ha^?1 in the uppermost 60 cm, if it is assessed by extraction with 0.016 m KH₂PO₄ or 0.5 m NaHCO₃ instead of 0.5 m NH₄F. Conversely, the pool of ester sulphate is overestimated almost threefold.     

Ameliorative Effects of Potassium Phosphate on Salt‐Stressed Pepper and Cucumber

Abstract

Bell pepper (Capsicum annuum cv. Urfa Isoto) and cucumber (Cucumis sativus cv. Beith Alpha F1) were grown in pots containing field soil to investigate the effects of supplementary potassium phosphate applied to the root zone of salt‐stressed plants. Treatments were (1) control: soil alone (C); (2) salt treatment: C plus 3.5 g NaCl kg^?1 soil (C + S); and (3) supplementary potassium phosphate: C + S plus supplementary 136 or 272 mg KH₂PO₄ kg^?1 soil (C + S + KP). Plants grown in saline treatment produced less dry matter, fruit yield, and chlorophyll than those in the control. Supplementary 136 or 272 mg KH₂PO₄ kg^?1 soil resulted in increases in dry matter, fruit yield, and chlorophyll concentrations compared to salt‐stressed (C + S) treatment. Membrane permeability in leaf cells (as assessed by electrolyte leakage from leaves) was impaired by NaCl application. Supplementary KH₂PO₄ reduced electrolyte leakage especially at the higher rate. Sodium (Na) concentration in plant tissues increased in leaves and roots in the NaCl treatment. Concentrations of potassium (K) and Phosphorus (P) in leaves were lowered in salt treatment and almost fully restored by supplementary KH₂PO₄ at 272 mg kg^?1 soil. These results clearly show that supplementary KH₂PO₄ can partly mitigate the adverse effects of high salinity on both fruit yield and whole plant biomass in pepper and cucumber plants.     

Extraction and speciation analysis of roxarsone and its metabolites from soils with different physicochemical properties

Purpose

The application of roxarsone (ROX), an arsenic-containing compound, as a feed additive in the animal production industry results in elevated soil levels of ROX and its metabolites, namely, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenate (As(V)), and arsenite (As(III)). This study was conducted to study the extraction and speciation analysis of ROX-related arsenicals in soils with different physicochemical properties and the possible effects of soil properties on the extraction of ROX and its metabolites.

Materials and methods

Analytical method based on high-performance liquid chromatography (HPLC)-inductively coupled plasma–mass spectrometry (ICP-MS) was employed to determine the concentrations of As(III), DMA, MMA, As(V), and ROX extracted by different extraction solvents from different soils spiked by arsenicals. Validity of the developed method was assessed by the recovery efficiencies of arsenic species in soil-dissolved matter solutions containing 20 μg As?·?L^?1 of each arsenic species. Effects of soil properties on the extraction of ROX and its metabolites were analyzed by Pearson’s correlation.

Results and discussion

Arsenic species were separated using gradient elution of water and 20 mmol?·?L^?1 (NH₄)₂HPO₄ + 20 mmol?·?L^?1 NH₄NO₃ + 5 % methanol (v/v) within 27 min. The linear ranges of all arsenicals were 0–200 μg As?·?L^?1 with R ²?>?0.9996. The developed method provided lower limits of detection for As(III), DMA, MMA, As(V), and ROX (0.80, 0.58, 0.35, 0.24, and 1.52 μg As?·?L^?1, respectively) and excellent recoveries (92.52–102.2 %) for all five species. Arsenic speciation was not altered by 0.1 mol?·?L^?1 NaH₂PO₄ + 0.1 mol?·?L^?1 H₃PO₄ (9:1, v/v), which offered better average extraction efficiencies for As(III), As(V), DMA, MMA, and ROX (32.49, 92.50, 78.24, 77.64, and 84.54 %, respectively). Extraction performance of arsenicals was influenced by soil properties, including pH, cation exchange capacity (CEC), total Fe, and amorphous Fe.

Conclusions

ROX and its metabolites from soils could be satisfactorily separated by the developed method for the studied arsenicals. To extract arsenic species from soils, 0.1 mol?·?L^?1 NaH₂PO₄ + 0.1 mol?·?L^?1 H₃PO₄ (9:1, v/v) was recommended. Extraction efficiencies of arsenicals were influenced more by solvent composition than soil physicochemical properties. The present study provides a valuable tool and useful information for determining the concentrations of ROX and its metabolites in contaminated soils.