Role of heavy polar organic compounds for water repellency of sandy soils

Separation and chemical characterisation of specific compounds responsible for soil water repellency has not previously been achieved. Here we describe the extraction, separation and analysis by gas chromatography-mass spectrometry of organic compounds found in wettable and water repellent sandy soils from the Netherlands and United Kingdom. Fatty acids (C₁₆–C₂₄), amides (C₁₄–C₂₄), alkanes (C₂₅–C₃₃), aldehydes/ketones (C₂₃–C₃₁) and complex ring-containing structures were detected in all samples. We found a greater abundance of high molecular mass polar compounds in the water repellent samples.     

Relative bioaccessibility of Pb-based paint in soil

The threat posed by lead (Pb) in soil for pediatric populations continues to be a public health issue. In long-established residential areas, a principal source of Pb in soil is likely to be old Pb-based paint originating from building surfaces. The health hazard posed by Pb from paint in soil will likely depend on quantity of paint incorporated, its Pb-mineral composition, whether the Pb is locked in some other material and the paint residence time in the soil (degree of aging). Here the relative bioavailability (RBA) of Pb in different types of Pb-bearing paint has been assessed. Tests were performed with individual paints, with paints mixed with a low-Pb soil, and with paints mixed with soil and the biogenic phosphate apatite II. Thirteen Pb-bearing paint samples were ground and passed through 250- and 100-µm screens. Samples nominally <100 µm from all the paints were analyzed, and six of the paints for which there was sufficient material in the 100- to 250-µm-size range were also tested. RBA extraction of Pb employed a simulated gastric fluid (SGF) of HCl and glycine adjusted to a pH of 1.5 in which samples were agitated (in an end-over-end rotator) for 2 h. Original paints were examined by SEM/EDX, and by XRD, residues collected after RBA extraction were examined by SEM/EDX. The concentration of Pb in the extraction fluid was measured by AAS. The quantity of Pb mobilized in each test batch was approximately an order of magnitude less in the paint–soil mix compared to the corresponding paint-only sample. The difference in the amount of Pb extracted from the paint–soil mix compared to the paint–soil–phosphate mix was minimal. However, in the post-RBA residues of the paint–soil mix, a PbCl precipitate was observed, and in the extraction residues of the paint–soil–apatite II mixes PbClP phases were recorded. Precipitation of these secondary phases obviously modified the amount of Pb in the extraction fluid, and this may need to be considered, i.e., under-reporting of extractable Pb, when this form of in vitro extraction is used to determine the RBA of Pb in environmental media.     

磁性介孔硅胶萃取剂的制备及萃取性能研究

合成了C18基团修饰的磁性介孔硅胶材料,并利用该材料建立了磁性固相萃取-色谱分析方法,测定了几种环境水样中酞酸酯类(PAEs)污染物的含量.结果表明,该材料具有较大的比表面积(273 m.2g-1)和饱和磁通量(29 emu.g-1),对水样中痕量的PAEs有较强的萃取能力,而且萃取剂的磁分离特性使得萃取操作更为方便、快捷.在优化条件下,30 mg萃取剂在40 min内即可从500 mL水样中萃取痕量PAEs,回收率可达80%以上.此外,该萃取剂在处理复杂环境样品时仍能保持较强的萃取能力,环境水样中4种PAEs的检测限可达15.6—32.5 ng.L-1,加标回收率为62%—109%,相对标准偏差为2%—8%.     

微囊藻毒素在土壤中的环境行为及污染风险

微囊藻毒素(Microcystins,MCs)是富营养化水体中发生蓝藻水华时所产生的一类肝毒素,在环境中大量出现时将对生态系统带来冲击并可通过食物链进入人体进而危害人类健康.关于微囊藻毒素的环境行为和污染风险近年来已成为研究热点.论文基于地表物质循环原理,分析了水体中微囊藻毒素经土壤进入人体的途径,指出了土壤在微囊藻毒素迁移转化链条中的位置,概述了微囊藻毒素在土壤中的环境化学行为、农作物的吸收特性及其生态毒理效应等方面的研究进展,提出了在微囊藻毒素迁移转化过程中土壤的净化和传递两大功能,并在此基础上展望了今后的研究方向.     

Genotoxic potential of organic extracts from municipal reclaimed water in Tianjin,China

Despite increasing pressure to make more efficient use of water resources, the widespread use of reclaimed water still remains a contentious issue, primarily because of risks to human health arising from water pollution by organic compounds. Therefore, safety evaluation of reclaimed water is an urgent need. The aim of this study was to determine the genotoxic potential of reclaimed water during low and high water periods. Reverse phase C-18 solid-phase extraction (RP-C18SPE) was used for the extraction of organic compounds from water samples. The tests, namely, Ames, micronucleus and chromosome aberrations were used to determine the damage caused by water samples on genetic material. Ames tests showed that both influent and effluent reclaimed water, except influent after metabolism by S9 in high water period, induced mutation of TA98 and TA100 strains of Salmonella typhimurium in a concentration-response manner. There were no significant differences in micronucleus and chromosome aberration tests. Even after treatment, reclaimed water in Tianjin still showed mutational effects and new strategies for reduction of genotoxins need to be considered.     

Determination of selected semi-volatile organic compounds in water using automated online solid-phase extraction with large-volume injection/gas chromatography/mass spectrometry

A rapid, sensitive, and cost-effective analytical method was developed for the analysis of selected semi-volatile organic compounds in water. The method used an automated online solid-phase extraction technique coupled with programmed-temperature vaporization large-volume injection gas chromatography/mass spectrometry. The water samples were extracted by using a fully automated mobile rack system based on x-y-z robotic techniques using syringes and disposable 96-well extraction plates. The method was validated for the analysis of 30 semivolatile analytes in drinking water, groundwater, and surface water. For a sample volume of 10 mL, the linear calibrations ranged from 0.01 or 0.05 to 2.5 ??g·L^?1, and the method detection limits were less than 0.1 ??g·L^?1. For the reagent water samples fortified at 1.0 ??g·L^?1 and 2.0 ??g·L^?1, the obtained mean absolute recoveries were 70%?C130% with relative standard deviations of less than 20% for most analytes. For the drinking water, groundwater, and surface water samples fortified at 1.0 ??g·L^?1, the obtained mean absolute recoveries were 50%?C130% with relative standard deviations of less than 20% for most analytes. The new method demonstrated three advantages: 1) no manipulation except the fortification of surrogate standards prior to extraction; 2) significant cost reduction associated with sample collection, shipping, storage, and preparation; and 3) reduced exposure to hazardous solvents and other chemicals. As a result, this new automated method can be used as an effective approach for screening and/or compliance monitoring of selected semi-volatile organic compounds in water.     

气相色谱／质谱测定电子垃圾拆解区土壤中四溴双酚A的方法

本研究建立气相色谱/质谱来测定电子垃圾拆解区土壤中四溴双酚 A（TBBPA）的方法。该化合物通过超声波辅助萃取,溶剂选择V（丙酮）﹕V（正己烷）=1﹕1或乙酸乙酯;净化柱选择酸化的氟罗里硅土和无水硫酸钠混合物或CleanertC18-SPE进行净化;净化液浓缩后经衍生反应,衍生试剂选用N,O-双（三甲基硅烷基）三氟乙酰胺（BSTFA）和含1%的三甲基氯硅烷（TMCS）。该方法测定电子垃圾拆解区土壤中TBBPA的检出限为（S/N=3）0.1μg·kg^-1加标回收率平均值为92.7%（n=5）,重现性RSD为2.52%（n=5）;线性范围是20～400μg·kg^-1相关系数0.999。该方法用于调查电子垃圾拆解区土壤中四溴双酚A,范围值为5.17～218.00μg·kg^-1其周围农田土壤中四溴双酚A,范围值为0.312～4.170μg·kg^-1     

固相微萃取-气相色谱/质谱联用法测定饮用水中苯类化合物

用固相微苹取(ＳＰＭＥ)－气相色谱/质谱联用法测定饮用水中苯类化合物,以１００μｍ ＰＤＭＳ(聚二甲基硅氧烷)萃取针提取、浓缩、分离与测定九种目标化合物．萃取时间经优化选定为８ｍｉｎ,而热解析时间设定为２ｍｉｎ． 本方法的相对标准偏差小于５%,线性范围宽(２０ｎｇ·ｍｌ－１－１００００ｎｇ·ｍｌ－１),多数化合物的检测限低于５μｇ·ｌ－１．饮用水样品检测显示,样品加标回收率范围在８４%至１１０%内．     

土壤宏蛋白质组学蛋白质提取方法及其应用

土壤宏蛋白质组学在揭示土壤微生物功能、代谢与环境相互作用方面具有广阔的应用前景,但由于土壤样品的特殊性,土壤蛋白质提取步骤是限制土壤宏蛋白质组学大规模应用的瓶颈之一.本文从样品制备、提取方法、影响因素等方面综述了土壤蛋白提取方面的研究进展.一般来说,根据实验目的、蛋白种类及后续研究方法设计相应的分组成收集策略才能取得较好的提取效果.土壤总蛋白、胞内蛋白与胞外蛋白分别有不同的提取方法.总蛋白提取一般采用直接提取法;胞外蛋白不需要裂解;胞内蛋白提取方法有直接提取法和间接提取法等.裂解、浓缩、去除腐殖质的方法以及提取液、pH值的选择等也会影响提取效果.此外,简单介绍了土壤宏蛋白质组学的应用,并对今后的研究工作提出展望.表1参36     

Bradford法测定土壤球囊霉素相关蛋白的影响因子

土壤球囊霉素相关蛋白(glomalin-related soil protein,GRSP)是评价土壤健康的重要指标。研究了土样粒径、贮存条件和高温提取后离心延误时间3个影响因子对采用Bradford法测定GRSP含量的作用效果。结果表明,土样粒径对易提取GRSP(EEG)的提取测定影响显著,过0.074 mm孔径筛土样中提取出的EEG含量高于过0.149、0.25、1 mm孔径筛的土样;总GRSP(TG)含量的测定结果对土样粒径的变化没有明显响应,测定TG含量可采用过1 mm孔径筛的土样。贮存条件影响EEG和TG含量的测定,有机质含量低的土样室温保存18个月条件下测得的EEG含量低于-20℃保存条件下;有机质含量高的土样室温保存条件下测得的EEG含量高于-20℃保存条件下;室温保存条件下3个有机质含量水平的土样TG含量均高于-20℃保存条件下。不同样品保存方式间3个有机质含量水平的土样EEG或TG含量差异均显著。为减小有机质降解等的影响,宜低温保存土样。提取后延误离心将导致EEG含量测定值降低,因此延误时间以控制在1 h之内为宜;离心延误2 h内不同延误时间之间测得的TG含量无显著差异。     

Soil drying in a tropical forest: Three distinct environments controlled by gap size

Soil water and temperature regimes in the tropical moist forest on Barro Colorado Island, Panama, were simulated directly from meteorological data using the model SWEAT. Separate field observations from root-exclusion, litter-removal and control treatments in one small and one large forest gap were used for calibration and validation. After irrigating all treatments to field capacity, soil matric potential and temperature were measured over 17 days at four depths ≤50 mm using the filter-paper technique and bead thermistors. Understorey environments were also simulated under the same initial conditions. The results suggest that three distinct scenarios, controlled by gap size, describe how the above- and below-ground processes controlling soil drying are coupled: (1) in the large gap, root water extraction by surrounding trees is negligible so soil drying is dominated by evaporation from the soil surface. Soil temperature is dominated by direct solar heating and cooling due to evaporation. (2) In the small gap, root water extraction dominates soil drying with soil evaporation playing a minor role. Soil temperature is still dominated by direct sunlight with some cooling due to evaporation. (3) In the understorey, root water extraction dominates soil drying. Soil temperature is dominated by heat conduction from deep soil layers with some evaporation and sensible heat transfer. The contrasting soil drying regimes imposed by variation in canopy structure enhance micro-environmental heterogeneity and the scope for differential germination and seedling establishment in coexisting tropical tree species.     

Analysis of herbicide residues by gas chromatography

The extraction and clean‐up, and gas Chromatographic conditions for the detection and determination of herbicides, their metabolites and related compounds are reviewed. The literature material is examined critically in the text and presented in tabular form for quick reference. The section dealing with extraction/clean‐up techniques is sub‐divided with respect to water, soil, plant material, animal, fish and micro‐organisms. Under eight herbicide group headings the important gas Chromatographic parameters such as stationary phase, support phase, column temperature and mode of detection are tabulated. Also tabulated are the application of various detectors to herbicide analyses and limits of detection where information was available. Most commonly used liquid and support phases are listed and their frequency of use given. Different aspects of derivative formation used for the positive identification and quantitation of herbicides are discussed with emphasis on esterification, alkylation and silylation. Other important conversion techniques are outlined, particularly those associated with enhancement of sensitivity e.g. bromination, iodination, dinitrophenylation etc. Efforts that have been made towards general and automated analytical methods are discussed.     

An efficient resin for solid-phase extraction and determination by UPLCMS/MS of 44 pharmaceutical personal care products in environmental waters

• A hydrophilic resin (GCHM) was facile synthesis and characterized. • Average absolute recovery of GCHM (75.6%) performs better than Oasis^® HLB. • Detection limits of method (SPE-UPLC-MS/MS) ranged between 0.03 and 0.6 ng/L. • 22 PPCPs were determined in environmental waters ranging from 0.5 to 1590 ng/L. In this study, a hydrophilic resin named GCHM was fabricated based on poly(N-vinyl pyrrolidone-co-divinylbenzene), characterized, and applied as a solid-phase extraction (SPE) material. Up to 44 pharmaceuticals and personal care products (PPCPs) belonging to 10 classes were recovered in environmental water samples. Different variables affecting extraction, such as adsorbent amount, sample pH, and loading speed, were optimized. Under optimal conditions, the average absolute recovery of 44 PPCPs was 75.6% using GCHM, indicating a better performance than the commercial Oasis^® HLB. SPE with home-made hydrophilic polymeric sorbent followed by ultra-performance liquid chromatography and tandem mass spectrometry was validated, and the method achieved good linearity (r²>0.991, for all analytes). In addition, the method detection limits of target compounds ranged from 0.03 to 0.6 ng/L. The developed method was applied to determine PPCPs in 10 environmental water samples taken from the Yangtze River, Huaihe River, and Taihu Lake, 1 groundwater sample from Changzhou in Jiangsu Province, 1 wastewater sample from Xiamen and 2 seawater samples from the Jiulong River in Fujian Province, China. In these samples, 22 compounds were determined at levels ranging from 0.5 to 1590 ng/L.     

Evaluating the respiratory bioaccessibility of nickel in soil through the use of a simulated lung fluid

Simulated lung fluids are solutions designed to mimic the composition of human interstitial lung fluid as closely as possible. Analysis of mineral dusts using such solutions has been used to evaluate the respiratory bioaccessibility of various elements for which solubility in the lungs is a primary determinant of reactivity. The objective of this study was to employ simulated lung fluid analysis to investigate the respiratory bioaccessibility of nickel in soils. Current occupational guidelines in Australia regulate nickel compounds in terms of water solubility, though this may not be an accurate estimation of the total nickel that will dissociate in the lungs. Surface soils were collected from the city of Kalgoorlie in Western Australia, the site of an operational nickel smelter and metal mining activities. The fraction of the samples less than 10 μm was extracted from the soil, and it was this sub-10-μm fraction that was found to hold most of the total nickel present in the soil. The fine fraction was analyzed using a simulated lung fluid (modified Gamble’s solution) to isolate the nickel phases soluble in the lungs. In addition, a sequential extraction was employed to compare the bioaccessible fraction to those dissolved from different binding forms in the soil. In all samples, the simulated lung fluid extracted more nickel than the two weakest leaches of the sequential extraction combined, providing a more representative nickel bioaccessibility value than the current water leach method.     

水体和甘蓝及土壤中毒死蜱残留检测方法

研究运用不同的样品前处理方式,在装配火焰光度检测器的气相色谱(GC-FPD)上检测,建立了有机磷杀虫剂毒死蜱在水样、土壤和甘蓝中的残留测定方法.研究表明,不同样品中的毒死蜱残留采用本文中介绍的前处理方法是可行的,用石油醚盐析提取和净化水样中毒死蜱,采用丙酮振荡提取甘蓝中毒死蜱,选用索氏提取法提取土壤中毒死蜱,并经液液分配净化后,采用OV-101大口径毛细管柱(30 m×0.53 mm×1.0μm),在装配火焰光度检测器(FPD和磷滤光片)的气相色谱上测定.该分析方法下,毒死蜱的保留时间为1.74 min,线性范围在1.0×10-11—1.0×10-8g之间,其线性相关系数为0.9998,最小检出量为2.0×10-12g.在设定的较低添加浓度的条件下,毒死蜱在水样、土壤与甘蓝上的添加回收率为80%—120%,变异系数均小于5%.该分析方法灵敏、准确、操作简便,适合水样、甘蓝和土壤中低浓度毒死蜱的残留检测.     

Crop growth,soil water and nitrogen balance simulation on three experimental field plots using the Opus model—A case study

Over a period of 5 years, the agro-ecosystem model Opus was used to simulate soil water and nitrogen balance as well as crop growth for three experimental field plots. At these plots, different agricultural management practices were applied. The data set obtained from these plots consists of automatically recorded time series of daily volumetric soil water contents measured by TRIME-probes as well as daily pressure heads measured by tensiometer. Aboveground total biomass, yield, nitrogen-uptake by crops as well as nitrate contents in the soil were measured at 6–10 sample times per year. The objective of this study was an evaluation of the accuracy of Opus regarding the simulation of crop growth, soil water and nitrogen balance. The simulations of soil water contents and pressure heads correspond with the commonly measured trends in soil depths shallower than 60 cm. In depths deeper than 60 cm, some differences between measured and simulated soil water contents as well as pressure heads could be observed. Nitrate contents in the root zone and the aboveground total biomass were simulated satisfactorily. In contrast to that, simulated and observed yields show greater discrepancies. This indicates the need of a site specific calibration of crop growth parameters within the Opus model.     

北方常见农作物根际土壤中铅、锌的形态转化及其植物有效性

采用盆栽试验结合形态分析技术研究了北方地区常见农作物对污染土壤中铅(Pb)、锌(Zn)的形态转化及其植物有效性的影响。土壤Pb、Zn形态分析结果显示,与非根际土壤相比,多数作物根际可交换态、碳酸盐结合态、有机质结合态Pb比例降低,而铁锰氧化物结合态、残渣态Pb则显著增加;Zn则表现为可交换态比例略呈降低趋势,碳酸盐结合态、铁锰氧化物结合态与有机质结合态升高,残渣态Zn则大幅下降。这提示,作物根际土壤Pb存在由松结合态向紧结合态转化的现象,从而植物有效性降低;而根际土壤Zn的形态变化则与Pb相反,即由紧结合态向松结合态转化,相应地提高了Zn的植物有效性。     

分散液液微萃取-石墨炉原子吸收光谱法测定环境水样中的痕量镉

建立了分散液液微萃取分离富集一石墨炉原子吸收光谱法测定环境水样中痕量镉的新方法。以二乙基二硫代氨基甲酸钠为螯合剂、四氯化碳为萃取剂、丙酮为分散剂,详细考察YpH值、螯合剂质量分数、萃取剂体积、萃取时间等因素的影响。在优化的实验条件下,方法对水样中镉的检出限为4．2ng-L^-1,线性范围是20-300ng-L^-1,测定结果的相对标准偏差为3．5％,富集倍数达103。将建立的方法应用于三种实际环境水样中镉的检测,加标回收率在92％-108％范围内。本方法具有灵敏、准确、快速、环保的特点,是一种分析水样中痕量镉的较好方法。     

Dynamic simulation of water depletion in the root zone

The joint effect of the distribution of the soil water potential and of the root mass in the crop root zone upon the water uptake by the crop is represented by a simple equation. This expression is used to join a layered crop canopy model for finding the evapotranspiration, as controlled by stomatal action and the weather, with a hydraulic flow model for the root zone and the underlying soil. The complete model is used for the calculation of the water extraction pattern and the changes, with time, of other plant and soil processes. A simulation of a 20-day drying period is performed, using S/360 CSMP, for a constant diurnal weather pattern, and for a fully developed sorghum crop. The results show that, after a few days of essentially constant water use by the crop, a monotonic decline sets in, that is principally attributable to the decrease in transpiration. For the entire drying period a substantial amount of water - about 30% of the total used - is contributed by upward flow into the root zone from the soil below. The results demonstrate the difficulty of quantitative definition of concepts such as “field capacity”, “wilting percentage”, and “available” or “extractable” water.     

Combined effect of fire and water scarcity on vegetation patterns in arid lands

In many arid zones around the word, the vegetation spontaneously forms regular patterns to optimize the use of the scarce water resources. The patterns act as early warning signal that fragile ecosystems may suddenly undergo irreversible shifts, thus, interpreting the structural shape of vegetation patterns is crucial to deciphering the ecosystem history and its expected further development. The sudden and irreversible shift of delicate ecosystems as a consequence of minor variation of the climatic forcing has been studied extensively in the past. The attitude of the ecosystem to recover after a catastrophic event, such as fire, did not receive as much attention so far. Here we modelled fire, as a sudden shift of the ecosystem state variables and functionality and evaluated post-fire scenarios under the hypothesis that two major feedbacks shaped the vegetation patterns: a positive feedback between preferential infiltration and plant growth, and a second feedback between infiltration and vegetation burning. A simple model solving a set of partial differential equations for soil moisture, plant biomass, surface water and dead biomass balance predicted significantly diverse post-fire vegetation patterns depending on the fire severity and on the degree of soil water repellency induced by the vegetation burning.