Implementation of depth-dependent soil concentrations in multimedia mass balance models

In standard multimedia mass balance models, the soil compartment is modeled as a box with uniform concentrations, which often does not correspond with actual field situations. Therefore, the theoretically expected decrease of soil concentrations with depth was implemented in the multimedia model SimpleBox 3.0. The effects of this implementation on the model outcomes were explored for nine compounds in four environmental compartments. For compounds with a low penetration depth, the new model predicts substantially higher or lower concentrations in the vegetation compartment than the old model. For those compounds, predicted concentrations in surface water and air were higher in the new model, but the deviations from the old model were smaller than in the vegetation compartment. For compounds with a large penetration depth, the model adaptations show little effect. No field study was carried out to validate the results of the model calculations, but we did collect measured data on concentrations in vertical soil profiles from literature. According to those data, we concluded that the implementation of depth dependent soil concentrations might be a useful extension for steady state multimedia mass balance models. More field study has to be carried out to validate the model outcomes.     

Analysis of rare-earth elements in soil sample by using laser-ablation ion trap mass spectrometry

Laser-ablation ion trap mass spectrometry (LA-ITMS) is applied for the analysis of rare-earth elements in soil samples. The target elements studied in this work were ytterbium (Yb) and samarium (Sm). The isotopic compositions of these elements were analyzed for standard samples with chip shape, the western phosphate rock sample (NIST SRM-694), and soil samples collected near our laboratory. For metal samples of Sm and Yb, isotopes of these elements as well as oxide forms were clearly identified. For the case of soil samples only a tentative assignment on the mass peaks were performed due to the complicated mass spectra that originated from the oxide forms of various rare-earth elements.     

动态反应池-电感耦合等离子体质谱法测定土壤中重金属元素

用微波消解/动态反应池-电感耦合等离子体质谱法测定土壤中的重金属。研究了微波消解以及影响测定的因素(多原子离子干扰及盐度等),研究表明:引入动态反应气NH3可有效消除多原子离子干扰;盐度小于2.0 g/L测定结果比较可靠。方法检出限为0.008~0.32μg/L,回收率为92%~109%。已应用于土壤样品的测定。     

Polycyclic aromatic hydrocarbons in the centralized wastewater treatment plant of a chemical industry zone: Removal, mass balance and source analysis

Increased attention has been given to the fate of pollutants such as polycyclic aromatic hydrocarbons (PAHs) introduced to the wastewater treatment plants.Dissolved and adsorbed PAHs were detected in the centralized wastewater treatment plant of a chemical industry zone in Zhejiang Province,China.The most abundant PAHs were the low molecular weight PAHs (e.g.,Acy,Ace,Flu and Phe),accounting for more than 80% of the total 16 PAHs in each treatment stage.Phase partitioning suggested that the removal of PAHs in every treatment stage was influenced greater by the sorption of particles or microorganisms.The removal efficiencies of individual PAHs ranged between 4% and 87% in the primary sedimentation stage,between 1% and 42% in anaerobic hydrolysis stage,between <1% and 70% in aerobic bio-process stage,between 1.5% and 80% in high-density clarifier stage,and between 44% and 97% in the whole treatment process.Mass balance calculations in primary stage showed significant losses for low molecular weight PAHs and relatively good agreements for high molecular weight PAHs as well as in anaerobic hydrolysis,high-density clarifier stage and sludge stream for most PAHs.Great gains of 60%-150% were obtained for high molecular weight PAHs in aerobic bio-process stage due to biosorption and bioaccumulation.Our investigations found that PAHs entering the wastewater treatment plant (WWTP) could be derived from the dyeing chemical processes as the byproducts,and the contribution supported by the largest dyeing chemical group was up to 48%.     

土壤中64种痕量半挥发性有机污染物的分析方法研究

利用超声提取技术将土壤中的半挥发性有机污染物(SVOC)提取出来, 经旋转蒸发浓缩至一定体积后, 用ODSC18柱净化, 再用氮吹浓缩后, 取1.0 μL注入气相色谱中, 用DB-5 ms柱分离, 用气相色谱质谱仪(GC-MS)进行定性定量分析. 本方法研究土壤中64种半挥发性有机污染物, 其中包括苯系物、苯酚类、苯胺类、硝基芳香烃类、氯代芳烃类、多环芳烃类和酞酸酯类等物质的提取、净化方法以及回收率、精密度和检测限的测定. 该方法回收率为52.5%～105%.     

ICP-MS测定土壤中铅同位素比值及地域差异性比较

建立用HNO_3-H_2O_2-HF体系微波消解前处理样品,利用电感耦合等离子体质谱测定土壤中铅同住素比值的方法,探讨并优化了影响测试结果的两种干扰因素.该方法中~(207)Pb/~(206)Pb和~(208)Pb/~(206)Pb的短期测量稳定性RSD分别达到0.12%和0.13%,长期测量的偏差分别在0.002和0.01以内,样品测量的最佳范围是10～40μg/L.采用标样-样品交叉法测定了湖南、湖北、云南、贵州、河南、福建、辽宁7个省的48个地区土壤中的铅同位素比值,结合聚类分析和主成分分析比较了各省土壤中同位素分布的差异,初步探讨了利用~(207)Pb/~(206)Pb和~(208)Pb/~(206)Pb比较烟叶产区的可能性.     

Slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry for the determination of As and Se in soil and sludge

Slurry sampling electrothermal vaporization (ETV) inductively coupled plasma mass spectrometry (ICP-MS) has been applied to determine As and Se in soil and sludge samples. The influences of instrument operating conditions and slurry preparation on the ion signals were reported. Pd and ascorbic acid were used as mixed modifiers to enhance the ion signals. The effectiveness of ETV sample introduction technique for alleviating various spectral interferences in ICP-MS analysis has been demonstrated. This method has been applied to determine As and Se in NIST SRM 2709 San Joaquin soil reference material and NIST SRM 2781 domestic sludge reference material and a farmland soil sample collected locally. Since the sensitivities of As and Se in slurry solution and aqueous solution were different, analyte addition technique was used to determine As and Se in these samples. The As and Se analysis results of the reference materials agreed with the certified values. The precision between sample replicates was better than 5% for all determinations. The method detection limit estimated from analyte addition curves was about 0.03 and 0.02 μg g⁻¹ for As and Se, respectively, in original soil and sludge samples.     

Multiresidue analysis of 36 pesticides in soil using a modified quick,easy, cheap,effective, rugged,and safe method by liquid chromatography with tandem quadruple linear ion trap mass spectrometry

A new method for simultaneous determination of 36 pesticides, including 15 organophosphorus, six carbamate, and some other pesticides in soil was developed by liquid chromatography with tandem quadruple linear ion trap mass spectrometry. The extraction and clean‐up steps were optimized based on the quick, easy, cheap, effective, rugged, and safe method. The data were acquired in multiple reaction monitoring mode combined with enhanced product ion to increase confidence of the analytical results. Validation experiments were performed in soil samples. The average recoveries of pesticides at four spiking levels (1, 5, 50, and 100 μg/kg) ranged from 63 to 126% with relative standard deviation below 20%. The limits of detection of pesticides were 0.04–0.8 μg/kg, and the limits of quantification were 0.1–2.6 μg/kg. The correlation coefficients (r²) were higher than 0.990 in the linearity range of 0.5–200 μg/L for most of the pesticides. The method allowed for the analysis of the target pesticides in the lower μg/kg concentration range. The optimized method was then applied to the test of real soil samples obtained from several areas in China, confirming the feasibility of the method.     

Residue determination of glyphosate, glufosinate and aminomethylphosphonic acid in water and soil samples by liquid chromatography coupled to electrospray tandem mass spectrometry

This paper describes a method for the sensitive and selective determination of glyphosate, glufosinate and aminomethylphosphonic acid (AMPA) residues in water and soil samples. The method involves a derivatization step with 9-fluorenylmethylchloroformate (FMOC) in borate buffer and detection based on liquid chromatography coupled to electrospray tandem mass spectrometry (LC-ESI-MS/MS). In the case of water samples a volume of 10 mL was derivatized and then 4.3 mL of the derivatized mixture was directly injected in an on-line solid phase extraction (SPE)-LC-MS/MS system using an OASIS HLB cartridge column and a Discovery chromatographic column. Soil samples were firstly extracted with potassium hydroxide. After that, the aqueous extract was 10-fold diluted with water and 2 mL were derivatized. Then, 50 microL of the derivatized 10-fold diluted extract were injected into the LC-MS/MS system without pre-concentration into the SPE cartridge. The method has been validated in both ground and surface water by recovery studies with samples spiked at 50 and 500 ng/L, and also in soil samples, spiked at 0.05 and 0.5 mg/kg. In water samples, the mean recovery values ranged from 89 to 106% for glyphosate (RSD <9%), from 97 to 116% for AMPA (RSD < 10%), and from 72 to 88% in the case of glufosinate (RSD < 12%). Regarding soil samples, the mean recovery values ranged from 90 to 92% for glyphosate (RSD <7%), from 88 to 89% for AMPA (RSD <5%) and from 83 to 86% for glufosinate (RSD <6%). Limits of quantification for all the three compounds were 50 ng/L and 0.05 mg/kg in water and soil, respectively, with limits of detection as low as 5 ng/L, in water, and 5 microg/kg, in soil. The use of labelled glyphosate as internal standard allowed improving the recovery and precision for glyphosate and AMPA, while it was not efficient for glufosinate, that was quantified by external standards calibration. The method developed has been applied to the determination of these compounds in real water and soil samples from different areas. All the detections were confirmed by acquiring two transitions for each compound.     

Determination of fatty acids in soil samples by gas chromatography with mass spectrometry coupled with headspace solid‐phase microextraction using a homemade sol–gel fiber†

Through the use of a homemade sol–gel‐derived fiber, a headspace solid‐phase microextraction technique coupled to gas chromatography with mass spectrometry was developed for the determination of fatty acids with long, even‐numbered carbon chains (C₁₂–C₂₄) in soil samples. The experimental parameters such as reaction time, temperature, and ionic strength that might affect derivatization, extraction, and desorption were investigated. Under the optimized conditions, the linearity of the method ranged from 0.1 to 100 mg/L with a correlation coefficient >0.997. The limit of detection values based on a signal‐to‐noise ratio of 3:1 were determined with the concentration from 0.39 to 39.4 μg/L. The recoveries of the method for the soil samples were from 91.15 to 108.1%. This developed method using a homemade fiber showed a higher sensitivity than that using a commercial polydimethylsiloxane fiber and was also for the analysis of real soil samples from the Paomaling geological park of China.     

Development and application of a dispersive solid-phase extraction method for the simultaneous determination of chloroacetamide herbicide residues in soil by gas chromatography-tandem mass spectrometry (GC-MS/MS)

In this study, a convenient and sensitive analytical method based on dispersive solid-phase extraction (dSPE) and gas chromatography-tandem mass spectrometry in tandem was developed for the simultaneous determination of six chloroacetamide herbicides (acetochlor, alachlor, metolachlor, metazachlor, butachlor and pretilachlor) in soil. Parameters that could influence the extraction efficiency such as the varieties of solvents, the amount of solvents and sorbents were investigated. The optimized extractions were performed by mixing 5.0 g of dried soil with 10.0 mL acetonitrile, 10.0 mL deionized water and 4.0 g sodium chloride, and then the extract was purified with 50.0 mg N-propyl ethylenediamine (PSA), 50.0 mg C18, 10.0 mg graphitized carbon black (GCB) and 100.0 mg MgSO₄ (5:5:1:10). At 5.0, 25.0 and 100.0 ng g^?1 fortification levels for each analyte, the average obtained recoveries ranged from 87.7% to 108.0% with relative standard deviation (RSD) between 3.8% and 10.9%. The soil matrix effect of the six compounds were lower than 11.0%. The linear relation was observed in the range of 5.0–500.0 ng g^?1 and the correlation coefficient (R²) of these compounds were higher than 0.998. The detection limits (LODs) were in the range of 0.2–1.0 ng g^?1, and the limits of quantification (LOQs) were between 0.8 and 2.2 ng g^?1. Comparing with the gas chromatography-electron capture detector (GC-ECD), the GC-tandem mass spectrometry (MS/MS) method can improve the anti-interference ability and thus get better separation of the chloroacetamide herbicides. Additionally, this method was verified to fit for soil samples with broad organic matter range (16.2 to 83.0 g kg^?1). The developed method was successfully applied for analysing 26 field soil samples collected from Dianchi lake basin in the southeast of China. About 42.0% soil samples were detected with these herbicides, of which butachlor was the most frequently detected and the highest concentration was up to 137.0 ng g^?1 in rape soil.     

Accelerated solvent extraction combined with dispersive liquid–liquid microextraction before gas chromatography with mass spectrometry for the sensitive determination of phenols in soil samples

A method combining accelerated solvent extraction with dispersive liquid–liquid microextraction was developed for the first time as a sample pretreatment for the rapid analysis of phenols (including phenol, m‐cresol, 2,4‐dichlorophenol, and 2,4,6‐trichlorophenol) in soil samples. In the accelerated solvent extraction procedure, water was used as an extraction solvent, and phenols were extracted from soil samples into water. The dispersive liquid–liquid microextraction technique was then performed on the obtained aqueous solution. Important accelerated solvent extraction and dispersive liquid–liquid microextraction parameters were investigated and optimized. Under optimized conditions, the new method provided wide linearity (6.1–3080 ng/g), low limits of detection (0.06–1.83 ng/g), and excellent reproducibility (<10%) for phenols. Four real soil samples were analyzed by the proposed method to assess its applicability. Experimental results showed that the soil samples were free of our target compounds, and average recoveries were in the range of 87.9–110%. These findings indicate that accelerated solvent extraction with dispersive liquid–liquid microextraction as a sample pretreatment procedure coupled with gas chromatography and mass spectrometry is an excellent method for the rapid analysis of trace levels of phenols in environmental soil samples.     

Application of pyrolysis-gas chromatography/mass spectrometry to study changes in the organic matter of macro- and microaggregates of a Mediterranean soil upon heating

The heating effect on the soil organic matter (SOM) of a Mediterranean soil was studied in two fractions (macro- and microaggregates) and in two environments (soil under canopy of Quercus coccifera and bare soil between plants). Samples were heated under laboratory conditions at different temperatures (220, 380 and 500°C) to establish their effects on the SOM quality and quantity by comparison with unheated control samples (25°C). The SOM content in the soil under canopy was higher than in the bare one and in the microaggregate fractions than in the macroaggregate ones. Increasing temperatures caused, in general, the decrease of SOM content in both soils as well as in both aggregate classes. The quality of SOM was determined after extraction with 0.1 M NaOH and analysed by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Obtained pyrolysates were characterized by the presence of polyphenols and other aromatic pyrolysis products (lipids, polysaccharides, proteins and lignin derivatives). Some of the products in these control samples, and furthermore the presence of black carbon (BC) markers (e.g. benzene, pyridine and toluene), confirmed the occurrence of past wildfires in the study zone. The composition of the SOM extracted from the soils heated at 220°C, was quite similar to that obtained from unheated soils. The products derived from polysaccharides and lignin, and some coming from polyphenols, were not detected in the pyrolysates of the soil heated at 380 and 500°C.     

Residue determination of plant activator benzo‐1,2,3‐thiadiazole‐7‐ carboxylic acid 2‐benzoyloxyethyl ester in water,soil, and vegetable by gas chromatography with tandem mass spectrometry

This study aimed to develop a rapid, specific and sensitive method for the residue determination of benzo‐1,2,3‐thiadiazole‐7‐carboxylic acid 2‐benzoyloxyethyl ester in soil, vegetable, and water by using gas chromatography with tandem mass spectrometry. During the extraction procedure, modified quick, easy, cheap, effective, rugged, and safe method using acetonitrile was compared with classical oscillating extraction using ethyl acetate and acetone, respectively. Before injection, a solid‐phase extraction cartridge of Bond Elut Florisil was used for sample clean‐up. The method was fully validated and showed satisfactory linearity (r² > 0.99) over the range to be assayed (10–1000 ng/mL), with the limits of detection ranging from 0.092–0.229 ng/mL and the limits of quantification ranging from 0.307–0.763 ng/mL. Recovery values at the spiked concentrations of 10, 100 and 1000 ng/g varied from 85.9–109.3%, 81.0–108.2%, 74.2–113.4% for water, soil and vegetable, respectively, with the maximum relative standard deviations of 12.2%. Results indicated that the established modified quick, easy, cheap, effective, rugged, and safe method coupled to gas chromatography with tandem mass spectrometry was promising for the residue monitoring of benzo‐1,2,3‐thiadiazole‐7‐carboxylic acid 2‐benzoyloxyethyl ester in the environment and vegetable products.