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1.
有机质对多环芳烃环境行为影响的研究进展 总被引：21，自引：3，他引：21
多环芳烃(PAHs)的归宿和毒性受其环境行为的影响,主要取决于环境中各个因素的交互作用,而有机质是相当重要的因素,有机质对环境中PAHs的物理化学行为、生物过程均有一定的影响。本文着重介绍了有机质对水体、土壤和沉积物中PAHs的吸附、溶解和迁移以及生物可利用性和毒性等方面的影响,总结了离子强度、pH、表面活性剂、时间等影响有机质与PAHs作用的因素,同时简要介绍了土壤和沉积物中结合残留态PAHs的研究情况,指出结合残留态PAHs现有的研究方法有热解法和同位素标记法,最后提出系统地研究内源有机质(尤其碳黑和腐殖酸)的组成、性质与土壤PAHs的锁定与降解的关系和利用外源有机物强化修复污染的环境是今后研究的重点。 相似文献
2.
Jesper Gamst Peter Kjeldsen Thomas H. Christensen 《Water, air, and soil pollution》2007,183(1-4):377-389
Groundwater risk assessment of contaminated soils implies determination of the solute concentration leaching out of the soil. Determination based on estimation techniques or simple experimental batch approach has proven inadequate. Two chemical equilibrium soil column leaching tests for determination of solute concentration in a contaminated soil were developed; (1) a chemical Equilibrium and Recirculation column test for Volatile organic chemicals (ER-V) and (2) a chemical Equilibrium and Recirculation column test for Hydrophobic organic chemicals (ER-H). The two test systems were evaluated using two soils with different content of organic carbon (foc of 1.5 and 6.5%, respectively). A quadruple blind test of the ER-V system using glass beads in stead of soil showed an acceptable recovery (65–85%) of all of the 11 VOCs tested. Only for the most volatile compound (heptane, KH～80) an unacceptable recovery was found (9%). The contact time needed for obtaining chemical equilibrium was tested in the ER-H system by performing five test with different duration (1, 2, 4, 7 and 19 days) using the low organic carbon soil. Seven days of contact time appeared sufficient for achieving a solute equilibrium concentration. The repeatability of both test systems (evaluated by performing five identical tests) was considered acceptable (8–16% and 7–28% for the ER-V and ER-H system, respectively). Comparing determined solute concentration in both systems for volatile and hydrophobic chemicals with estimated concentrations using an Kow–Koc relation and determined total soil concentrations, large differences between measured and estimated solute concentrations were observed, especially for the hydrophobic chemicals (PAHs). This clearly illustrates the need for a reliable method to measure solute phase concentration of PAHs in contaminated soils. Overall a reliable and reproducable system for determining solute concentration of a wide range of organic compounds in contaminated soils has been developed. 相似文献
3.
采集某污染区千金子(Euphorbia lathyris L.)和酢浆草(Oxalis corniculata L.)的离根表0~3、3~6、6~9 mm的根际土壤,分析了多环芳烃(PAHs)结合态残留中母体化合物(Parent compound of bound residue,PCBR)在根际土壤中的含量及梯度分布规律。供试土壤类型为黄棕壤。结果表明,在非根际和根际土壤中均可检出10种PAHs的PCBR,非根际土壤中PCBR总含量为3.31 mg kg-1,高于根际土壤(1.07~1.82mg kg-1)。根际土壤中PAHs的PCBR含量随离根表距离(0~9 mm)的增加而增大。可用根际效应(R)来衡量根际土壤中PAHs的PCBR含量与非根际土壤相比减少的比例;R值随离根表距离(0~9 mm)的增加而变小。3个连续根际区中,PAHs总PCBR的R值为45.15%~67.66%,其中2环PAH的R值最大(61.18%~93.50%),4环和5环PAHs的R值最小(2.39%~6.31%),低环PAHs的PCBR在根际土壤中更易转化。PAHs的PCBR在千金子根际土壤中R值大于酢浆草,表明前者有更利于PAHs结合态残留转化的根际环境。PAHs结合态残留的根际梯度分布与根系分泌物的梯度分布关系密切,而PAHs种类、植物根际环境对PAHs结合态残留的分布影响显著。 相似文献
4.
Bert van Bavel 《Journal of Soils and Sediments》2006,6(4):208-214
Background, Aim and Scope
Polycyclic aromatic hydrocarbons (PAHs) are formed as a result of incomplete combustion and are among the most frequently
occurring contaminants in soils and sediments. PAHs are of great environmental concern due to their ubiquitous nature and
toxicological properties. Consequently, extensive research has been conducted into the development of methods to remediate
soils contaminated with PAHs. Fenton's reagent or ozone is the most commonly studied chemical oxidation methods. However,
the majority of remediation studies use soils that have been artificially contaminated with either one or a limited number
of PAH compounds in the laboratory. Hence, it is essential to extend such studies to soils contaminated with multiple PAHs
under field conditions.
Objectives The objective of this study is to investigate the capacity of Fenton's reagent and ozone to degrade PAHs in soils. The soils
have been collected from a number of different industrial sites and, therefore, will have been exposed to different PAH compounds
in varying concentrations over a range of time periods. The capacity of Fenton's reagent and ozone to degrade PAHs in industrially
contaminated soils is compared to results obtained in studies using soils artificially contaminated with PAHs in the laboratory.
Materials and Methods:
Nine soil samples, contaminated with PAHs, were collected from five different industrial sites in Sweden. For the Fenton's
reagent procedure, the pH of the soil slurry samples was adjusted to pH 3 and they were kept at a constant temperature of
70oC whilst H2O2 was added. For the ozone procedure, soil samples were mixed with 50% water and 50% ethanol and kept at a
constant temperature of 45 oC. Ozone was then continually introduced to each soil sample over a period of four hours. Following
the Fenton's reagent and ozone oxidation procedures, the samples were filtered to isolate the solid phase, which was then
extracted using pressurized liquid extraction (PLE). The sample extracts were cleaned up using open columns and then analysed
by gas chromatography-mass spectrometry (GC-MS).
Results:
The relative abundance of the detected PAHs varied between soils, associated with different industries. For example, low molecular
weight (LMW) PAHs were more abundant in soil samples collected from wood impregnation sites and high overall PAH degradation
efficiencies were observed in soils originating from these sites. In the contaminated soils studied, PAHs were more effectively
degraded using Fenton's reagent (PAH degradation efficiency of 40-86%) as opposed to ozone (PAH degradation efficiency of
10-70%). LMW PAHs were more efficiently degraded, using ozone as the oxidizing agent, whereas the use of Fenton's reagent
resulted in a more even degradation pattern for PAHs with two through six fused aromatic rings.
Discussion:
The degradation efficiency for both methods was largely dependent on the initial PAH concentration in the soil sample, with
higher degradation observed in highly polluted soils. LMW PAHs are more susceptible to degradation than high molecular weight
(HMW) PAHs. As a result of this the relative abundance of large (often carcinogenic) PAHs increased after chemical oxidation
treatment, particularly after ozone treatment. Repeated Fenton's reagent treatment did not result in any further degradation
of soil PAHs, indicating that residual soil PAHs are strongly sorbed. The effectiveness of the two oxidation treatment approaches
differed between industrial sites, thus highlighting the importance of further research into the influence of soil properties
on the sorption capacity of PAHs.
Conclusions:
This study demonstrates that the degree to which chemical oxidation techniques can degrade soil bound PAHs chemical degradation
is highly dependent on both the concentration of PAHs in the soils and the compounds present, i.e. the various PAH profiles.
Therefore, similarities in the PAH degradation efficiencies in the nine soil samples studied were observed with the two chemical
oxidation methods used. However, the degradation performance of Fenton's reagent and ozone differed between the two methods.
Overall, Fenton's reagent achieved the highest total PAH degradation due to stronger oxidation conditions. LMW PAHs showed
higher susceptibility to oxidation, whereas high molecular weight (HMW) PAHs appear to be strongly sorbed to the soils and
therefore less chemically available for oxidation. This study highlights the importance of including soils collected from
a range of contaminated sites in remediation studies. Such soil samples will contain PAH contaminants of varying concentrations,
chemical and physical properties, and have been aged under field conditions. In addition to the chemical and physical properties
of the soils, these factors will all influence the chemical availability of PAHs to oxidation.
Recommendations and Perspectives:
We recommend including aged contaminated soils in chemical degradation studies. In future chemical remediation work, we intend
to investigate the potential influence of the chemical and physical properties of PAHs and soil parameters potential influence
on the chemical oxidation efficiency in aged contaminated soils.
Due to the vast number of contaminated sites there is a great need of efficient remediation methods throughout the world.
This study shows the difficulties which may be experienced when applying remediation methods to a variation of contaminated
sites. 相似文献
5.
John J. Kilbane II 《Water, air, and soil pollution》1998,104(3-4):285-304
The biodegradation of polyaromatic hydrocarbons (PAHs) has been well documented; however, the biodegradation of PAHs in contaminated soil has proved to be problematic. Sorption of PAHs to soil over time can significantly decrease their availability for extraction much less than for biodegradation. In this study the ability of various organic solvents to extract PAHs from coal tar-contaminated soil obtained from former manufactured gas plant (MGP) sites was investigated. Solvents investigated included acetone/hexane, dichloromethane, ethanol, methanol, toluene, and water. The extraction of MGP soils with solvents was investigated using soxhlet extraction, multiple soxhlet extractions, sonication, and brief agitation at ambient temperature with a range of solvent concentrations. Of particular interest was the documentation of the recalcitrance of PAHs in weathered MGP soils to extraction and to bioremediation, as well as to demonstrate the ease with which PAHs extracted from these soils can be biodegraded. The efficiency of extraction of PAHs from MGP soils was found to be more dependent upon the choice of solvent. The environmentally-benign solvent ethanol, was shown to be equal to if not better than acetone/hexane (the EPA recommended solvent) for the extraction of PAHs from MGP soils, brief contact/agitation times (minutes) using small quantities of ethanol (2 volumes or less) can achieve nearly quantitative extraction of PAHs from MGP soils. Moreover aqueous slurries of an MGP soils experienced less than 10% biodegradation of PAHs in 14 days while in the same period about 95% biodegradation was acieved using PAHs extracted from this soil by ethanol and subsequently added to aqueous bacterial suspensions. 相似文献
6.
厌氧微生物降解是环境中多环芳烃（polycyclic aromatic hydrocarbons,PAHs）污染削减的重要途径。为系统、全面地了解PAHs厌氧微生物降解的研究现状,以Web of Science核心数据库为数据源,对该领域已发表文献进行文献计量分析,并以厌氧环境中不同还原条件对应的电子受体还原体系为切入点,分别论述反硝化体系、金属离子还原体系、硫酸盐还原体系和产甲烷体系中的PAHs厌氧微生物降解的研究进展,在此基础上重点对土壤中PAHs厌氧微生物降解研究的现存理论空白和未来发展趋势进行探讨。分析结果表明,PAHs厌氧微生物降解领域的研究整体较少,其中,绝大多数仅针对低环PAHs;不同还原条件中对产甲烷和金属离子还原体系的关注也较少;已有研究多侧重纯培养物或水体、沉积物等环境介质,较少基于土壤展开,且新兴技术在该领域尚未得到广泛应用。因此,目前针对土壤中PAHs厌氧微生物降解的认识尚存在诸多理论空白。土壤是环境中PAHs汇集和积累的重要场所,未来应当尝试将单体稳定同位素分析、稳定同位素核酸探针、组学等多种新兴技术与传统研究方法相结合,从多种的角度深入探究土壤PAHs厌氧微生物降解的机制,并将已有的理论和经验在土壤中进行验证,以填补现存理论空白,推进厌氧土壤中PAHs污染微生物修复工作的开展。 相似文献
7.
Background and Scope Many technologies available to remediate soils are not cost-effective when applied to marine and lagoon sediments, due to
the physico-chemical characteristics of these matrices (high percentages of small particle size material, high moisture and
organic matter content, many different types of inorganic and organic contamination). For these types of waste, slurry phase
bioreactors can provide versatile processes, with very high removal efficiencies of recalcitrant organic compounds. The biodegradation
of these contaminants strictly depends on the specific structure of the molecules and on environmental factors, such as the
dissolved oxygen concentration, salinity, pH, and macronutrient availability.
This paper presents the results of lab-scale tests performed to investigate the effect of the above-mentioned factors on the
removal efficiency of saturated hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs) in slurry
phase biological treatment of lagoon sediments.
Methods Sediments were contaminated by saturated hydrocarbons (958 mg/kg d.w.), polyaromatic hydrocarbons (PAHs) (29 mg/kg d.w.) and
polychlorobiphenyls (PCBs) (236 μg/kg d.w.). Carbon to nitrogen to phosphorous ratios in the matrix were not properly balanced
for biological treatment. High concentrations of metals were also present (Cu: 200 mg/kg d.w.; Zn: 1710 mg/kg d.w.; As: 33
mg/kg d.w.; Cd: 13 mg/kg d.w.; Pb: 244 mg/kg d.w.).
Biodegradation studies were carried out at 21 ± 1°C, in completely mixed slurry phase aerobic, anaerobic and sequential anaerobic/aerobic
batch systems (3.5 1), with a solid to liquid ratio of 10% w/w. Where required, anaerobic conditions occurred naturally within
three days of not aerated treatment. The aerated reactors were also equipped with traps for the waste vapors. Twelve tests
were performed, over a period between ten and twenty-two days, mixing water, sediments and different amounts of various additives
(macronutrients to balance C:N:P to 100:10:1 w/w, sodium chloride from 0 to 20 g/1, pH buffer solution) in the reactors, depending
on the test being performed.
Results and Discussion No significant differences among the removal efficiencies of saturated hydrocarbons in tests could be observed. Abatements
between 63% and 93% were obtained.
The dissolved oxygen concentration was the most critical factor affecting the treatment of PAHs. Removal efficiencies below
20% were obtained for two and three-ring PAHs in the non-aerated tests. Higher values, between 45% and 61%, were obtained
for these compounds in the aerated treatments; however, large (16% to 21%) abiotic losses (volatilization) were observed in
these cases. Four-ring PAH removal efficiency was below 5% in all the non-aerated treatments, except for test performed without
additions (30%); in the aerobic processes, removal efficiencies between 40% and 50% were obtained, except for test performed
with nutrient addition and 10 g NaCl/1 (16%). Abatements of five and six-ring PAHs were between 43% and 69% in the aerated
tests, and between 17% and 51% in the non-aerated treatments.
Concerning PCBs, tests evidenced that reductive dehalogenation mechanisms have occurred in the anaerobic reactors with the
most stable pH values, resulting in an increase of 2,4,4′-CB and 2,2′,5,5′-CB concentrations; the aerobic treatments did not
modify the PCB mixture. In both types of systems, no variation of the total PCB concentration could be observed.
Conclusions This study showed that saturated hydrocarbon removal efficiency was nearly insensitive to the environmental factors investigated.
The molecule structure and the dissolved oxygen concentration were the most affecting factors the removal efficiency of PAHs.
PCB degradation under anaerobic conditions could be related to the pH values measured during the tests. Evaluation of results
suggested that the abatement of pollutants investigated was not limited by a high salinity. High concentrations of dissolved
metals and macronutrient addition did not influence the removal efficiency.
Recommendations and Outlook. The slurry phase biological treatment of contaminated sediments could be applied whenever moderate
removal efficiencies were required for remediation from saturated hydrocarbons and PAHs within a few days; further studies
should be performed to improve the PCB abatement. Aerobic conditions should be maintained for the biodegradation of polyaromatic
compounds; seawater or lagoon water could be used in the system. 相似文献
8.
Purpose
Little information is available heretofore on the gradient distribution of persistent organic pollutants in rhizosphere on a field scale. In this field study, we seek to explore the in situ distribution gradient of polycyclic aromatic hydrocarbons (PAHs) in rhizosphere soil proximal to the roots.Materials and methods
Clover (Trifolium pratense L.) and hyssop (Hyssopus officinalis L.) grew in situ in the contaminated field soil near a petrochemical plant and were harvested when about 30 cm tall with mature roots. Rhizosphere soils of the plants were sampled including the rhizoplane, strongly adhering soil, and loosely adhering soil. Eleven EPA-priority PAHs were detected in each layer of rhizosphere soils in proximity to the root surface.Results and discussion
The PAH concentrations followed the descending order of bulk soil, loosely adhering soil, strongly adhering soil, and rhizoplane soil in proximity to the root surface of clover and hyssop. The rhizosphere effect (R, in percent) on PAH distribution clearly decreased with increasing distance from the root, and a more significant decrease was observed for hyssop compared to clover. R values were generally lower for three- and four-ringed PAHs in the rhizosphere, which were more significant in loosely and strongly adhering rhizosphere layers.Conclusions
Our field observations combined with previous potted studies demonstrated that PAH concentrations in rhizosphere soils increased with distance from the root. Results of this work provide new information on the fate of PAHs in rhizosphere. 相似文献9.
Availability of polycyclic aromatic hydrocarbons in aging soils 总被引：1，自引：0，他引：1
Wanting Ling Yuechun Zeng Yanzheng Gao Hongjiao Dang Xuezhu Zhu 《Journal of Soils and Sediments》2010,10(5):799-807
Purpose
The soil contamination by hydrophobic organic contaminants (HOCs), such as polycyclic aromatic hydrocarbons (PAHs), poses great threats to human health and ecological security and attracts worldwide concerns. The total HOC concentrations overestimate its available fraction to the soil biota. Increased understanding of the availabilities of PAHs in soil environment will have considerable benefits for their risk assessment and be very instructive to food safety and remediation strategies in contaminated sites. However, the availability of PAHs in aging soils and particularly the correlations of the availabilities with their forms in soils have yet to be elucidated. In this work, the availabilities of PAHs in aging soils were evaluated using a sequential mild extraction technique. 相似文献10.
Use of the BCR three-step sequential extraction procedure for the study of the partitioning of Cd, Pb and Zn in various soil samples 总被引：1，自引：0，他引：1
A slightly modified three-step sequential extraction procedure proposed by the Community Bureau of Reference (BCR) for analysis
of sediments was successfully applied to soil samples. Contaminated soil samples from the lead and zinc mining area in the
Mezica valley (Slovenia) and natural soils from a non-industrial area were analysed. The total concentrations of Cd, Pb and
Zn and their concentrations in fractions after extraction were determined by flame or electrothermal atomic absorption spectrometry
(FAAS, ETAAS). Total metal concentrations in natural soils ranged from 0.3 to 2.6 mg kg-1 for Cd, from 20 to 45 mg kg-1 for Pb and from 70 to 140 mg kg-1 for Zn, while these concentrations ranged from 0.5 to 35 mg kg-1 for Cd, from 200 to 10000 mg kg-1 for Pb and from 140 to 1500 mg kg-1 for Zn in soils from contaminated areas. The results of the partitioning study applying the slightly modified BCR three-step
extraction procedure indicate that Cd, Pb and Zn in natural soils prevails mostly in sparingly soluble fractions. Cd in natural
soils is bound mainly to Fe and Mn oxides and hydroxides, Pb to organic matter, sulphides and silicates, while Zn is predominantly
bound to silicates. In contaminated soils, Cd, Pb and Zn are distributed between the easily and sparingly soluble fractions.
Due to the high total Cd, Pb and Zn concentrations in contaminated soil close to the smelter, ! and their high proportions
in the easily soluble fraction (80% of Cd, 50% of Pb and 70% of Zn), the soil around smelters represents an environmental
hazard. 相似文献
11.
Lee Sangjin Kommalapati R. R. Valsaraj K. T. Pardue J. H. Constant W. D. 《Water, air, and soil pollution》2004,158(1):207-221
Microcosm batch studies were conducted to study the biodegradation of 1,3-dichlorobenzene (1,3-DCB) from the aqueous (soil free) and soil phases. For soil phase experiments, a freshly contaminated soil and a soil containing only the desorption-resistant or irreversibly bound or non-labile fraction of the contaminant were used. These experiments were designed to simulate biodegradation at Superfund site assuming sorption/desorption equilibrium was reached. The presence of the soil reduced the rates of biodegradation significantly. Nearly 100% of the total 1,3-DCB in the aqueous phase was biodegraded by enriched bacterial cultures within 7 days compared to about 55% over a 6-week incubation period from the freshly contaminated soil. The biodegradation in the soils containing only the desorption-resistant fraction of the contaminant was considerably lower (about 30%). It is believed that for freshly contaminated soil, 1,3-DCB readily desorbed into the aqueous phase and was available for microbial consumption whereas for soils containing mostly the desorption-resistant fraction of 1,3-DCB, the contaminant availability was limited by the mass transfer into the aqueous phase. Our earlier studies concluded that about 20–30% of the sorbed contaminant is tightly bound (even larger for weathered or aged soils) and is not easily extractable. This fraction is typically present in micropores or chemically bound to soil humic matter and thus is not readily accessible for microbial utilization. The findings presented here for 1,3-DCB are in agreement with those reported for other chemicals in the literature and could have implications to the current remedy, the monitored natural attenuation at the Petro Processors Inc. Superfund site in Louisiana. 相似文献
12.
Jaime Mello William Roy Jonathan Talbott Joseph Stucki 《Journal of Soils and Sediments》2006,6(1):9-19
Background Soils and sediments in certain mining regions of Brazil contain an unusually large amount of arsenic (As), which raises concerns
that mining could promote increased As mobility, and thereby increase the risks of contaminating water supplies.
Objectives The purpose of this study was to identify the most important factors governing As mobility in sediments and soils near three
gold-mining sites in the State of Minas Gerais, Brazil.
Methods Surface and sub-surface soil samples were collected at those sites and characterized by chemical and mineralogical analyses.
Oxalate (Feo) and citrate-bicarbonate-dithionite (Fed) iron contents were determined by atomic absorption spectroscopy (AAS).
Arsenic mobilization was measured after incubating the samples in a 2.5 mM CaCl2 solution under anaerobic conditions for 1,
28, 56, 84, or 112 days. The solution concentrations of As, Fe, and Mn were then measured by inductively coupled plasma-mass
spectrometry (ICP-MS) and AAS, respectively.
Results and Discussion Results indicated that As mobilization is largely independent of both the total As and the Feo/Fed ratio of the solid phase.
Soluble As is roughly controlled by the Fe (hydr)oxide content of the soil, but a closer examination of the data revealed
the importance of other highly weathered clay minerals and organic matter. Large amounts of organic matter and a low iron
oxide content should favor As leaching from soils and sediments. Under reducing conditions, As is mobilized by the reductive
dissolution of Fe and/or Mn oxides. However, released As may be readsorbed depending on the sorptive properties of the soil.
Gibbsite is particularly effective in adsorbing or readsorbing As, as is the remaining unreduced fraction of the iron (hydr)oxides.
Conclusion and Outlook In general, low soluble As is related to the presence of gibbsite, a large amount of iron oxides, and a lack of organic matter
in the solid phase. This has environmental significance because gibbsite is thermodynamically more stable than Fe oxides under
anaerobic conditions, such as those found in waterlogged soils and lake sediments. 相似文献
13.
14.
Gómez R. S. García Pandiyan T. Iris V. E. Aguilar Luna-Pabello V. de Bazúa C. Durań 《Water, air, and soil pollution》2004,158(1):137-151
The determination of poly-aromatic hydrocarbons (PAHs) in the soil is of interest because of their carcinogenic and mutagenic activity in biological systems. The present study deals with the rapid application of infrared, fluorescence, synchronous luminescence spectrometries and gas chromatography to detect organic pollutants and their quantity in the soil. Sohxlet extraction followed by column separation was used to isolate organic pollutants. Although several solvent mixtures were used as eluents for the column, the solvent mixture, hexane:dichloromethane (50:50) efficiently extracts the aromatic compounds. Total petroleum hydrocarbons (TPH) measured by IR were found at high concentrations (30810.0 ppm) in the contaminated soil compared with the reference soil (30.0 ppm). Furthermore, the fluorescence results reveal that almost one-fourth of the 30810.0 ppm are aromatic hydrocarbons. In addition, the presence of PAHs such as naphthalene, acenaphthene, fluorene, fluoranthene, phenanthrene, pyrene, benzo(a)pyrene, chrysene, and dibenzo(a,h)anthracene in the polluted soil was determined by using synchronous study. 相似文献
15.
A. N. Gennadiev Yu. I. Pikovskii R. G. Kovach T. S. Koshovskii N. I. Khlynina 《Eurasian Soil Science》2016,49(5):529-537
Modifications of the hydrocarbon status (HCS) of soils at the stages of the injection input of oil pollutants and the subsequent self-purification of the soil layer from technogenesis products have been revealed in studies conducted on an oil field. Comparison with the HCS of background soils has been performed. Changes in the composition and concentration of bitumoids, polycyclic aromatic hydrocarbons (PAHs), and hydrocarbon gases have been established. The HCS of a freshly contaminated soil is characterized by the predominance of butane (the highest component) in the gaseous phase, an abrupt increase in the concentration of second-kind bitumoids, and a 100-fold increase in the content of PAHs compared to the background soil. In the old contaminated soil, free and fixed methane becomes the predominant gas; the content of bitumoids in the upper soil horizons is lower than in the freshly contaminated soils by two orders of magnitude but higher than in the background soil by an order of magnitude; the PAH composition in the soil with old residual contamination remains slightly more diverse than in the background soil. 相似文献
16.
Torsten Vor Jens Dyckmans Heiner Flessa Friedrich Beese 《Biology and Fertility of Soils》2002,36(1):66-71
Microbial heat production is a nonspecific measure for microbial activity irrespective of O2 availability in soils. In a series of long-term batch microcalorimeter experiments with closed ampoules, we examined the microbial activity in glucose-amended soil aggregates from different soil depths of a clay forest soil during the transition from aerobic to anaerobic conditions. Furthermore, the influence of the soil aggregate size on the long-term metabolic heat production was examined. Heat output curves showed a distinct pattern for soil samples from different soil depths and aggregate sizes and led to the following conclusions: 1. Microbial biomass and microbial activity strongly decreased with increasing soil depth as well as increasing soil aggregate size despite relatively constant organic C concentrations. 2. The transition from aerobic to anaerobic conditions led to a considerable drop in microbial activity. However, based on the energy balance, 10-26% of the heat production during the aerobic phase is attributable to anoxic or partly anoxic metabolism. 3. After O2 exhaustion, a lag phase of low but constant heat output was observed, followed by a peak of anaerobic metabolic activity. Heat production during the lag phase was hypothesised to be an indicator for the biomass of facultatively anaerobic microorganisms in the soil. 相似文献
17.
Determination of effective release rates of polycyclic aromatic hydrocarbons and dissolved organic carbon by column outflow experiments 总被引：2，自引：0，他引：2
Risk assessment of groundwater pollution requires quantitative information on the release kinetics of pollutants and organic matter from contaminated soil. We applied a new experimental design for column outflow experiments to investigate the release of polycyclic aromatic hydrocarbons (PAHs) and dissolved organic matter under water-saturated flow conditions. We used materials originating from a soil contaminated with non-aqueous phase liquids. To distinguish between release at equilibrium and release limited by mass transfer, we used two flow velocities and multiple interruptions to the flow. We quantified release and transport parameters by inverse numerical simulation of the individual breakthrough curves, applying a model based on the advection–dispersion equation including non-equilibrium and non-linear sorption. Release of the dissolved organic C takes place in two steps. Initially, a large amount of readily available organic matter is released. This first flush is followed by an outflow with typical characteristics of rate-limited release: larger concentrations in slower flow and increased concentrations after interruptions. The breakthrough of PAHs responds neither to the different flow velocities nor to the interruptions. We hypothesize that release of PAHs from the contaminated material is governed by dissolution at equilibrium according to Raoult's law. The boundary conditions of the experimental design, i.e. the flow velocities and multiple interruptions, enable us to distinguish between release at equilibrium and that which is rate-limited. Also, the response of the breakthrough behaviour to the boundary conditions can be used to estimate inversely effective release parameters. 相似文献
18.
金鑫 FredrickOrori Kengar 王芳 谷成刚 杨兴伦 Ulrike Doerfler Reiner Schroll Jean Charles Munch 蒋新 《土壤学报》2017,54(1):108-117
氯代持久性有机污染物的农田土壤污染呈现污染浓度低、面积大、新源污染不断输入的特点。农田土壤本身微生物种类丰富,对氯代有机污染物具有较大的降解潜力和未知性。本试验以典型高氯代和低氯代持久性有机污染物——六氯苯(HCB)和滴滴涕(DDT)为研究对象,结合~(14)C同位素示踪技术,研究HCB和DDT在热带水稻土和甘蔗地土壤的矿化现象,同时监测HCB和DDT在两种土壤中的挥发、降解产物以及结合残留。结果表明,经84 d好氧培养,HCB和DDT在两种土壤中的矿化量分别仅为0.14%和3%,低氯代有机污染物DDT的矿化速率显著高于高氯代有机污染物HCB。然而,两种土壤对HCB或DDT的矿化没有显著性差异。HCB或DDT在水稻土中的挥发量略微高于甘蔗地土壤,两种土壤中HCB和DDT的挥发量在0.1%~0.6%之间,表明挥发不是其主要的环境过程。在DDT污染水稻土和甘蔗地土壤中添加1.25%的堆肥增加了DDT在土壤中的矿化与结合残留,减少了DDT的挥发。本研究结果表明土壤在好氧条件下对氯代持久性有机污染物的自然消解能力非常弱,而有机肥的使用有助于土壤中持久性氯代有机污染物的矿化消除。 相似文献
19.
Dickson Johnbull O. Mayes Melanie A. Brooks Scott C. Mehlhorn Tonia L. Lowe Kenneth A. Earles Jennifer K. Goñez-Rodriguez Leroy Watson David B. Peterson Mark J. 《Journal of Soils and Sediments》2019,19(4):2007-2019
Purpose
In contaminated streams, understanding the role of streambank and streambed source contributions is essential to developing robust remedial solutions. However, identifying relationships can be difficult because of the lack of identifying signatures in source and receptor pools. East Fork Poplar Creek (EFPC) in Oak Ridge, TN, USA received historical industrial releases of mercury that contaminated streambank soils and sediments. Here, we determined relationships between the contaminated streambank soils and sand-sized streambed sediments.
Materials and methodsField surveys revealed the spatial trends of the concentrations of inorganic total mercury (Hg) and methyl mercury (MeHg), Hg lability as inferred by sequential extraction, particle size distribution, and total organic carbon. Statistical tests were applied to determine relationships between streambank soil and streambed sediment properties.
Results and discussionConcentrations of Hg in streambank soils in the upper reaches averaged 206 mg kg?1 (all as dry weight) (n?=?457), and 13 mg kg?1 in lower reaches (n?=?321), while sand-sized streambed sediments were approximately 16 mg kg?1 (n?=?57). Two areas of much higher Hg and MeHg concentrations in streambank soils were identified and related to localized higher Hg concentrations in the streambed sediments; however, most of the streambank soils have similar Hg concentrations to the streambed sediments. The molar ratio of Hg to organic carbon, correlation between MeHg and Hg, and particle size distributions suggested similarity between the streambank soils and the fine sand-sized fraction (125–250 μm) collected from the streambed sediments. Mercury in the fine sand-sized streambed sediments, however, was more labile than Hg in the streambank soils, suggesting an in-stream environment that altered the geochemistry of sediment-bound Hg.
ConclusionsThis study revealed major source areas of Hg in streambank soils, identified possible depositional locations in streambed sediments, and highlighted potential differences in the stability of Hg bound to streambank soils and sediments. This work will guide future remedial decision making in EFPC and will aid other researchers in identifying source–sink linkages in contaminated fluvial systems.
相似文献20.
PAH release from tar-oil contaminated soil material in response to forced environmental gradients: implications for contaminant transport 总被引：1，自引：1，他引：0
Laboratory test systems are frequently used to assess the release of pollutants from contaminated sites. To infer behaviour in the field, all factors that control the release of such pollutants should be considered in the experiment. We carried out column experiments with varying boundary conditions under saturated flow to identify the processes governing the release and to evaluate the effect of environmental conditions on several polycyclic aromatic hydrocarbons (PAHs). We compared the results with groundwater concentrations monitored in the field. The contaminated soil material originated from a former tar‐processing site. The effluent was analysed in response to forced variations in flow velocity, residence time, ionic strength and temperature. Interruptions to the flow had no effect on concentrations, which were close to those predicted by Raoult’s law. We conclude that release of PAHs is controlled by equilibrium dissolution according to Raoult’s law at moderate ionic strength. Diminishing the ionic strength by a pulse of pure water, however, results in a marked increase in the concentrations of exported PAHs. We attribute this to PAHs being bound to mobile particles. The effect was larger in the column percolated with fast flow, suggesting that the release of carriers is controlled by shear stress. An increase of temperature by 10 K resulted in marked increases in concentrations of the PAHs in the outflow between 6 and 160%. Concentrations in the groundwater correlate well with those in the outflow from the columns with similar ionic strength and temperature. We were able to identify the processes governing the release of PAHs under various conditions and to explain the concentrations observed in the field. The study illustrates that column outflow experiments, which support decisions in risk assessment, must be designed appropriately. 相似文献