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.     

Simultaneous determination of the quantity and isotopic signature of dissolved organic matter from soil water using high-performance liquid chromatography/isotope ratio mass spectrometry

We assessed the accuracy and utility of a modified high-performance liquid chromatography/isotope ratio mass spectrometry (HPLC/IRMS) system for measuring the amount and stable carbon isotope signature of dissolved organic matter (DOM) <1 μm. Using a range of standard compounds as well as soil solutions sampled in the field, we compared the results of the HPLC/IRMS analysis with those from other methods for determining carbon and (13)C content. The conversion efficiency of the in-line wet oxidation of the HPLC/IRMS averaged 99.3% for a range of standard compounds. The agreement between HPLC/IRMS and other methods in the amount and isotopic signature of both standard compounds and soil water samples was excellent. For DOM concentrations below 10 mg C L(-1) (250 ng C total) pre-concentration or large volume injections are recommended in order to prevent background interferences. We were able to detect large differences in the (13)C signatures of soil solution DOM sampled in 10 cm depth of plots with either C3 or C4 vegetation and in two different parent materials. These measurements also demonstrated changes in the (13)C signature that demonstrate rapid loss of plant-derived C with depth. Overall the modified HLPC/IRMS system has the advantages of rapid sample preparation, small required sample volume and high sample throughput, while showing comparable performance with other methods for measuring the amount and isotopic signature of DOM.     

An intercomparison of sampling techniques for measurements of radiocaesium in upland pasture and soil

An intercomparison of sampling procedures used by five laboratories for the determination of radiocaesium in vegetation and peaty soil was carried out at two locations in Cumbria. The multiple sampling has given information on the homogeneity of the parameters studied at each location. The parameters comprise soil bulk densities, total deposition of¹³⁷Cs, deposition of¹³⁷Cs in three soil layers, biomass densities, concentrations of¹³⁷Cs in pasture, and activity ratios (¹³⁴Cs/¹³⁷Cs) in soil and vegetation. The determination of total deposition of¹³⁷Cs gave no indication of differences between the laboratories. The results from the soil profiles do indicate significant differences between laboratories. One laboratory using a coring technique observed difficulties during sampling due to compression of the soil. The coring technique should thus be avoided or applied with extreme care for the sampling of depth profiles in peaty soil. The results from the sampling of pasture show no indication of differences between the laboratories. For the parameters studied the observed variabilities across soil depths and locations range from 10% to 81% in terms of relative standard deviations. A comparison across all results at the two locations indicate a 50% higher field variability at one of the sites relative to the other.     

Influence of recent vegetation on labile and recalcitrant carbon soil pools in central Queensland, Australia: evidence from thermal analysis-quadrupole mass spectrometry-isotope ratio mass spectrometry

The effect of a recent vegetation change (<100 years) from C(4) grassland to C(3) woodland in central Queensland, Australia, on soil organic matter (SOM) composition and SOM dynamics has been investigated using a novel coupled thermogravimetry-differential scanning calorimetry-quadrupole.mass spectrometry-isotope ratio mass spectrometry (TG-DSC-QMS-IRMS) system. TG-DSC-QMS-IRMS distinguishes the C isotope composition of discrete SOM pools, showing changes in labile, recalcitrant and refractory carbon in the bulk soil and particle size fractions which track the vegetation changes. Analysis of evolved gases (by QMS) from thermal decomposition, rather than observed weight loss, proved essential in determining the temperature at which SOM decomposes, because smectite and kaolinite clays contribute to observed weight losses. The delta(13)C analyses of the CO(2) evolved at different temperatures for bulk soil and particle size-separates showed that most of the labile SOM under the more recent woody vegetation was C(3)-derived carbon whereas the delta(13)C values in the recalcitrant SOM showed greater C(4) contributions. This indicated a shift from grass (C(4))- to tree (C(3))-derived carbon in the woodland, which was also supported by the two-phase (13)C enrichment with depth, i.e. C(3) vegetation dominated the top soil (0-10 cm), but the C(4) contribution increased with depth (more gradual). This is perturbed by the inclusion of charcoal from forest fires ((14)C age incursions) and by the deep incorporation of C(3) carbon due to root penetration.     

Improved sample preparation for MALDI–MSI of endogenous compounds in skin tissue sections and mapping of exogenous active compounds subsequent to ex-vivo skin penetration

Localization of endogenous and exogenous compounds directly in tissue sections is a challenging task in skin research. Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is a powerful label-free technique that enables determination of the distribution of a large range of biomolecules directly in tissue sections. Nevertheless, its application in this field is limited in large part by the low adhesion of skin tissue sections to indium–tin oxide-coated (ITO) glass slides. For the first time corona discharge (CD) treatment was used to modify the glass slide surface for improved adhesion. Localization of endogenous cholesterol sulfate was performed directly in human skin tissue sections. A spatial resolution of approximately 30 μm was sufficient for assignment of mass signals to skin structure morphology. Furthermore, imaging of an exogenous model compound, Nile red, was performed directly in skin tissue sections after ex-vivo penetration into porcine skin, enabling determination of the pathway and depth of penetration. Finally, the ion density map of Nile red was compared with its high resolution fluorescence micrograph. This work provides new insights into the application of MALDI–MSI in skin research.     

Distribution of Hydrocarbons in Soil Through Contamination from a Leaking Natural Gas Pipeline

Abstract

A plume of hydrocarbon contamination in soil from a leaking natural gas pipeline located at a depth of 80 cm was defined on the basis of discoloration of soil at 3 to 7 cm depth. Eleven sites were selected randomly on a grid superimposed on a map of the 240 m² plume and 48 soil samples at depths from 7 cm to 150 cm were collected. Samples were individually extracted using cyclohexane in a Soxhlet extraction apparatus. Condensed extracts were analyzed using capillary GC and GC/MS techniques to determine quantitatively the dinstribution of C₁₀ to C₃₅ hydrocarbons in soil. In solvent extracts of the soils, over 150 organic compounds were resolved and detected at total concentrations from 0.1 to 2700 ppm. The vertical distribution of hydrocarbons was consistent throughout the plume with higher concentrations of all components with increased proximity to the surface. The hydrocarbons moved vertically from the leak and diffused horizontally along an interface created at 15 to 30 cm by the addition 20 years earlier of a dense clay soil to a naturally high-gypsum base. Ratios of soil concentrations in three size ranges for the hydrocarbons were used to evaluate the physical mechanism for gaseous migration and environmental fate of the hydrocarbons. These ratios were not uniform at every site and depth throughout the plume. Results were consistent with differences in mobility and fate of the hydrocarbons in the soil based on volatility and adsorption. Polycyclic aromatic hydrocarbons present in the natural gas and in the pipeline residue were also found in some but not all soil samples under the conditions of extraction and analyses which were not optimized in the soil-extraction of the aromatic compounds.     

Fruit tree model for uptake of organic compounds from soil

Apples and other fruits are frequently cultivated in gardens and are part of our daily diet. Uptake of pollutants into apples may therefore contribute to the human daily intake of toxic substances. In current risk assessment of polluted soils, regressions or models are in use, which were not intended to be used for tree fruits. A simple model for uptake of neutral organic contaminants into fruits is developed. It considers xylem and phloem transport to fruits through the stem. The mass balance is solved for the steady-state, and an example calculation is given. The Fruit Tree Model is compared to the empirical equation of Travis and Arms (T&A), and to results from fruits, collected in contaminated areas. For polar compounds, both T&A and the Fruit Tree Model predict bioconcentration factors fruit to soil (BCF, wet weight based) of >1. No empirical data are available to support this prediction. For very lipophilic compounds (log K OW >5), T&A overestimates the uptake. The conclusion from the Fruit Tree Model is that the transfer of lipophilic compounds into fruits is not relevant. This was also found by an empirical study with PCDD/F. According to the Fruit Tree Model, polar chemicals are transferred efficiently into fruits, but empirical data to verify these predictions are lacking.     

Pollution Potential of Some Triazole Pesticides

Abstract

The widespread occurrence of pesticides, especially in the groundwater has stimulated research into the behavior of these agrochemicals in the environment. In this work a simple model to describe the fate of the two triazole fungicides Flutriafol and Flusilazol in a silt soil is presented. For this purpose we constructed mini-columns of soil, on which we applied the two fungicides, the percolation waters and the soils were collected at different times and the pesticides quantified in these samples. In the first part, these experiments were carried out outdoors during a period of 6 months on the silt soil and in a second part, we did similar indoor experiments with the same soil and with two others. To complete our work, we studied the adsorption of these two compounds on these three types of soil with batch equilibrium experiments. The results demonstrate that the fungicide Flusilazol is an immobile compound in soil, being strongly adsorbed whatever the nature of the soil. The Flutriafol is slightly to moderately mobile in the different soils, being less adsorbed.     

Ignition and burning behaviors of automobile oil in engine compartment

Accidental leakage of automobile oils is of great inclination to initiate pool fires in engine compartment, with threats to induce the flashover of other components and flame penetration into the passenger compartment. This paper presents experimental results of the ignition and burning behaviors of a kind of automobile oils (automatic transmission oil) using a cone calorimeter. Measurements of oil temperature, ignition time, mass loss and heat release rate are performed at different external heat fluxes and initial fuel depths. The comparison between experimental and numerical oil temperature evolutions shows that the variations of the ignition time at different experimental conditions depend on the heat dissipation process inside the liquid phase. The steady mass burning rate is nearly independent of initial fuel depth and has a linear relation with external heat fluxes. In addition, the results indicate an increase in peak heat release rate by a large margin initially, followed by a relatively small margin under thicker initial fuel depths, while its variations are proportional to external heat fluxes. Correlations are also developed to determine the peak heat release rate as a function of the initial fuel depth.

     

Environmental dose assessment using Ecolego: case study of soil from Japan

From the Fukushima incident, a number of radionuclides were released, causing radioactive contamination to the environment. Depending on their own half-lives, the radionuclides, however, will decay over time. During the decay, those radionuclides can be transferred to the ecosystem and, eventually, to humans. As part of the environmental surveillance and restoration program, radiological dose assessments have been carried out in response to the incident to prevent a potentially unacceptable dose to the public. This study focuses on the deposition of certain radionuclides in soil and their transport through the terrestrial food chain. Soil from two sites, Namie and Iitate, where radioactive contamination is evident was used as the source term. The assessment has been conducted using Ecolego, a simulation software used for conducting dose assessments of complex dynamic systems evolving over time especially in the field of radiology. Possible pathways from the soil used as the source term to humans as well as crops, forage, livestock products, and milk, for specific radioactive species have been studied. The dose assessment results of I-131, Cs-134, Cs-137, Sr-89, and Sr-90 in each compartment of the food chain are presented in this literature. The concentrations of the studied radionuclides vary from one medium to another, resulting from the characteristic of the medium itself along with other factors, such as the half-lives and transfer factors. Due to the fact that the concentrations of the radionuclides are affected by the depth of soil, there may be some uncertainty of the dose assessment results from the model.     

双极膜电渗析法处理工业高盐香料废水

采用双极膜电渗析法处理某企业的工业高盐香料废水,旨在将无机盐氯化钠从香料废水中脱除并转化为附加值更高、较高浓度的盐酸和氢氧化钠. 当一次性处理3 L废水时,保证了足够的处理时间,生成盐酸和氢氧化钠的浓度分别能达到1.93 mol·L^-1和1.70 mol·L^-1,脱盐率为99.4%,生成盐酸和氢氧化钠的电流效率分别为30.7%和36.0%,电耗为2.58 kW·h·kg^-1. 分别通过向盐室中补加废水原料和氯化钠固体的方式,均可抑制盐室中氯化钠浓度的减小,将生成的氢氧化钠浓度显著地提高,且后者提高的程度更为明显. 为提高酸、碱产品的纯度,分别考察了阳离子交换膜和阴离子交换膜对Cl^-和Na⁺的阻隔效果,阳离子交换膜对Cl-的阻隔效果有着JAM-II>N2030>TRJCM的顺序,阴离子交换膜JAM-II对Na⁺的阻隔效果高于TRJAM. JCM-II相比于N2030膜有着更低的膜电阻. 综合考虑使用JAM-II/BPM-I/JCM-II组合时效果最好,电耗最低.     

Determination of Fluorine in Vegetation by Proton Activation Analysis

Abstract

Techniques have been developed for proton activation analysis using the ¹⁹F(p,p′y)¹⁹F reaction to measure the fluorine content of pulverized samples of vegetation which have been exposed to fluorides in the atmosphere or soil. The method is non-destructive and neither the chemical form of fluorine in the sample nor the type of vegetation analyzed appears to affect results. Calibration is performed by analyzing samples to which known amounts of fluorine are added. The fluorine content of 11 vegetation samples was determined by proton activation analysis and by standard chemical techniques. The values obtained by the two methods were in generally good agreement. Fluorine concentrations greater than 1 ppm can be measured with uncertainties ranging from about 50% at 5 ppm to less than 10% at concentrations above 50 ppm.     

Lignans and secoiridoid glycosides from the stem barks of Jasminum tortuosum

This paper reports on the first phytochemical analysis ever performed on Jasminum tortuosum Willd. This analysis, mainly carried out by means of column chromatography separation, NMR spectroscopy and mass spectrometry, led to the isolation and the identification of four compounds, namely the lignans ginkgool (1) and olivil-4′-O-β-glucopyranoside (2) and the secoiridoids oleoside dimethyl ester (3) and oleoside 11-methyl ester (4). The presence of these compounds is significant from a chemotaxonomic point of view, confirming the correct botanical classification of the species and, from a phytochemical standpoint, may suggest its possible use in the ethno-medicinal field.     

Analysis of Chlorinated Phenols,Phenoxyphenols and Dibenzofurans Around Wood Preserving Facilities

Abstract

Until presently chlorophenol containing wood preservative has been widely used in Finland to protect timber, lumber, plywood and fiberboard against rot and bluestaining fungi at saw mills. We analysed soil, ground water, runoff and workers' urine at several saw mills for the presence of the various chemical components of the commercial wood preservative.

We found serious local contamination of soil with chlorophenols and also with the minor, potentially very toxic minor constituents of the commercial product, namely polychlorinated phenoxyphenols and dibenzofurans. Chlorophenols were observed to contaminate soil at great depth. Ground water, surface water and also workers' urine was found contaminated by chlorophenols. Polychlorinated phenoxyphenols and dibenzofurans were found in great quantity (equal or close to that of chlorophenols) in the topmost 5cm of soil at the sawmill area, but these compounds had not penetrated into the soil at such great depth as did chlorophenols.     

Incorporation of (15)N from spiked cattle dung pats into soil under two moorland plant communities

The rate and depth of cattle dung incorporation into moorland soil may be an important factor influencing plant community dynamics through its effects on soil nutrient availability. This study traces the incorporation of (15)N-labelled dung into a moorland soil under two vegetation types in Dartmoor National Park, UK. Cores of treated and control soil 10 cm deep were collected at 2, 4, 8 and 16 week intervals and divided into 2 cm depth increments. Soil samples were freeze-dried, ground and analysed for atom% (15)N and %N content using continuous-flow isotope-ratio mass spectrometry. The contribution of dung N to the soil N pool was estimated by changes in atom% (15)N of the soil. The incorporation of dung dry matter into the soil was also calculated. The labile component of the dung N was incorporated deeper and more rapidly into soil under grass than under heather vegetation. The implications of these processes for the dynamics of upland plant communities are considered in relation to the ability of plants to compete for nutrients.     

Migration of ions in capillary electrochromatography

For capillary electrochromatography (CEC) to be a generally used analytical technique the origin of the unusual, and often unwanted, peak shapes, which regularly occur for ionic compounds, must be understood. A mass balance analysis is the most fundamental approach to investigate the origin of non-linear effects during the migration of an eluite. Such an analysis shows that a CEC system composed of ionic compounds has a complex behaviour and that a variety of peak shapes for an eluite ion is expected. In this paper it is shown that the mass balance analysis is rationalised by the introduction of the non-dimensional electrochromatographic migration number omega. This number is defined as the ratio Eu/v0k, where E is the effective electric field strength in the eluite zone, u the mobility of the eluite, v0 the linear velocity of the mobile phase and k the chromatographic capacity factor of the eluite. This work is focussed on the theoretical behaviour of a CEC system for analytical applications, i.e., in the limit of low eluite concentrations. Even under analytical conditions the three-component system studied in this paper shows strong peak broadening when omega has values close to unity.     

INVESTIGATION OF POWER ABSORPTION BY METHYLENE BLUE IN A LIGHT SCATTERING MEDIUM WITH AN INTERNAL PHOTODYNAMIC ACTINOMETER

Abstract— Power absorption by aqueous solutions of methylene blue containing high concentrations of polystyrene microspheres was measured at 650 nm, using the photosensitized inactivation of subtilisin Carlsberg as an internal actinometer. The results were analyzed with the one-dimensional diffusion approximation for a finite slab. It is shown that the power absorption is determined by two macroscopic parameters, the optical penetration depth and the linear absorption coefficient. The optical penetration depth was determined independently by measuring flux profiles with an inserted fiber-optic method. The results are in satisfactory agreement with the predictions of the diffusion model, with microsphere diameters from 0.5 to 5 μm and a wide range of scatterer and dye concentrations. The presence of the scatterers diminished the power absorbed by the dye in all cases. The predictions of one-dimensional diffusion model are compared to Kubelka-Munk theory, and shown to be equivalent for optically dense systems     

INFLUENCE OF SOIL MOISTURE AND VEGETATION ON CLIMATE (Ⅰ)——THEORETICAL ANALYSIS TO PERSISTENCE OF SHORT-TERM CLIMATE ANOMALIES

Influence of soil moisture and vegetation on persistence of short-term climate anomalies isanalyzed theoretically through a heat and water balance model in coupled air-land system.It is shown that the soil hydrologic condition, rather than the soil thermal situation, is adominant factor in maintenance of climatic anomalies. The persistence of climate anomaliesis dependent largely on the capacity of water and heat exchange on the land surface. The cli-mate anomalies would persist longer for less soil moisture or vegetation cover. Furthermore,compared with humid areas, the climate anomalies persist longer in an arid climate envi-ronment.     

Effect of lignocellulosic degradation compounds from steam explosion pretreatment on ethanol fermentation by thermotolerant yeast Kluyveromyces marxianus

The filtrate from steam-pretreated poplar was analyzed to identify degradation compounds. The effect of selected compounds on growth and ethanolic fermentation of the thermotolerant yeast strain Kluyveromyces marxianus CECT 10875 was tested. Several fermentations on glucose medium, containing individual inhibitory compounds found in the hydrolysate, were carried out. The degree of inhibition on yeast strain growth and ethanolic fermentation was determined. At concentrations found in the prehy-drolysate, none of the individual compounds significantly affected the fermentation. For all tested compounds, growth was inhibited to a lesser extent than ethanol production. Lower concentrations of catechol (0.96 g/L) and 4-hydroxybenzaldehyde (1.02 g/L) were required to produce the 50% reduction in cell mass in comparison to other tested compounds.     

Determination of brain and plasma drug concentrations by liquid chromatography/tandem mass spectrometry

A method is described for the evaluation of drug concentrations in plasma and brain from treated rats. The analyte is recovered from plasma or brain homogenate by liquid-liquid extraction and subsequently analyzed by liquid chromatography/tandem mass spectrometry (LC/MS/MS). A simple experimental protocol renders the procedure valuable for obtaining information rapidly on brain penetration and plasma exposure of specific classes of compounds. This methodology has been applied to evaluate brain penetration with 30 different compounds from the same discovery program. In an attempt to increase throughput in our screening efforts, mixture dosing was evaluated. Results from single compound administration were compared with results following administration of a mixture of four compounds. Preliminary results, with specific classes of compounds, show no major differences (ranking order) in brain or plasma concentrations between mixture dosing and single compound administration, suggesting that mixture dosing could be applicable to brain penetration studies in the drug discovery phase.