表面活性剂对植物修复有机污染土壤的增效作用及原理

Phytoremediation is becoming a cost-effective technology for the in-situ clean up of sites polluted with hydrophobic organic contaminants （HOCs）. The major factors limiting phytoremediation are the mass transfer, rate of plant uptake, and microbial biodegradation of HOCs. This article discusses the potential of surfactants to enhance desorption, plant uptake, and biodegradation of HOCs in the contaminated sites. Positive effects of surfactants on phytoremediation have been recently observed in greenhouse studies. The presence of some nonionic surfactants including polyoxyethylene sorbltan monooleate （Tween 80） and polyoxyethylene（23）dodecanol （Brij35） at relatively low concentrations resulted in significant positive effects on phytoremediation for pyrene-contaminated soil. However, the anionic surfactant （sodium dodecyl sulfate, SDS） and the cationic surfactant （cetyltrimethylammonium bromide, CTMAB） were not useful because of their phytotoxicity or low efficiency for surfactant-enhanced phytoremediation （SEPR）. The mechanisms of SEPR for HOC-contaminated sites were evaluated by considering experimental observations. In view of concerns about the cost effectiveness and toxicity of surfactants to plants, more research is needed to enhance the use of SEPR technology.     

Bioavailability of hydrophobic organic contaminants in soils: fundamental concepts and techniques for analysis

Soils represent a major sink for organic xenobiotic contaminants in the environment. The degree to which organic chemicals are retained within the soil is controlled by soil properties, such as organic matter, and the physico‐chemical properties of the contaminant. Chemicals which display hydrophobic and lipophilic characteristics, as well as a recalcitrant chemical structure, will be retained within the soil, and depending on the ‘strength’ of the association may persist for long periods of time. This review describes the behaviour of hydrophobic organic contaminants in soils, focusing on the mechanisms controlling interactions between soil and contaminants. The bioavailability of contaminants in soil is also discussed, particularly in relation to contact time with the soil. It considers the degradation of organic contaminants in soil and the mechanisms microbes use to access contaminants. Finally, the review discusses the ‘pros’ and ‘cons’ of chemical and biological techniques available for assessing bioavailability of hydrophobic organic chemicals in soils, highlighting the need to quantify bioavailability by chemical techniques. It concludes by highlighting the need for understanding the interactions between the soil, contaminants and biota which is crucial to understanding the bioavailability of contaminants in soils.     

Behaviour and assessment of bioavailability of organic contaminants in soil: relevance for risk assessment and remediation

Abstract. Soils contaminated with organic chemicals are now widespread in industrialized and developing countries, and the risk assessment and remediation of such contaminated sites is a priority. However, containment and remediation strategies are complicated in many cases by the range of contaminants present and the historical nature of the contamination. Research has increased our understanding of the behaviour of organic contaminants in soil and the factors that control their behaviour. There is a fundamental need to understand and, where possible, quantify the bioavailable fraction as well as the total concentration of contaminant present in soil: the bioavailable fraction is key to toxicity or biodegradation. To quantify these fractions, a large number of techniques have been employed, ranging from organic and aqueous based solvent extractions to the use of biota. Many studies have been carried out investigating the use of chemical techniques to describe bioavailability, which could be used in the assessment and remediation of contaminated land. The aim of this review is to consider the behaviour of organic contaminants in soil, highlighting issues of bioavailability, and then to discuss the relevance of the various methods for assessing risk and potential remediation of organic contaminants in soil.     

Predicting bioaccessibility of contaminants of emerging concern in marine sediments using chemical methods

Journal of Soils and Sediments - A comparison was made between three chemical methods to predict bioaccessibility of triclosan (TCS), bisphenol A (BPA), and 17α-ethynylestradiol (EE2) in...     

Estimation of buffering capacity of mangrove soils by using hydrophobic organic compounds,atrazine and linuron

Samples of two soils and two sediments collected at sites originating from mangrove forests in Thailand, were examined in terms of buffering capacity to organic compounds. Atrazine and linuron were used as representative hydrophobic organic compounds for estimating the buffering capacity by observing their adsorptive and desorptive behavior. The buffering capacity could be represented by the distribution of the adsorption ratio (AR) and desorption ratio (DR) as follows: AR (%) = (amount of herbicide adsorbed per unit weight of soil)/(initial amount of herbicide) x 100, and DR (%) = (amount of herbicide desorbed per unit weight of soil after herbicide desorption experiments) / (initial amount of adsorbed herbicide on soil) x 100. The soil under mangrove forests displayed a larger buffering capacity to atrazine and linuron. Compared with 42 soils from Japan, in terms of the adsorption proparty of atrazine and linuron, the mangrove soil ranked in a higher category on the classification of the Japanese soils. Thus, the importance of maintaining or recovering the mangrove forests to promote environmental conservation was emphasized.     

Geochemical behavior assessment and apportionment of heavy metal contaminants in the bottom sediments of lower reach of Changjiang River

Heavy metal contamination of bottom sediments of the Changjiang River is widely reported, however, the potential source and methods of transportation of these heavy metals in the contaminated sediments is poorly defined. This paper examines the correlation between heavy metals and geochemical indices, including Fe₂O₃, Al₂O₃, total organic carbon (TOC) and black carbon (BC), as well as magnetic susceptibility (MS). Using these indices we investigate the contamination characteristics of heavy metals in the sediments by with Principal Component Analysis (PCA). Results from 83 sediment samples collected in the lower reach of Changjiang River (from Nanjing to Shanghai) show that the first principal component accounts for 52.23% of the total variance, corresponding to the heavy metals, Co, Cr, Cu, Ni and Zn, and conservative components of Fe₂O₃, Al₂O₃ and TOC. This result indicates that heavy metal distributions are controlled by the transportation and sedimentation of fine particles which is also confirmed by particle size analysis. The second principal component explains 24.81% of the variance and is dominated by Cd, Pb and MS, which, collectively, result chiefly from industrial and transportation activities and, for MS, fly ash production. The third principal component accounts for 7.91% of the variance and corresponds solely to Hg. Principal component analysis/multiple linear regression (PCA/MLR) was used to estimate the contribution of the three principal components to each heavy metal. PCA/MLR results suggest that more than 50% of Co, Cr, Cu, Ni and Zn were influenced by the particle size effect. Particle size effect and fly ash account for 37.1% and 27.7% of As. Cd and Pb were mainly explained by fly ash. 98.9% of Hg was related to PC3, which represented black carbon (BC). Our study indicates that the combination of geochemical and multivariable statistical methods clearly characterizes the geochemistry of heavy metals in sediment of the lower reaches of the Changjiang River and suggests that power plants are the main source of heavy metal pollution.     

The determination of NH3-concentration gradients in a spruce forest using a passive sampling technique

In order to estimate the influence of NH₃ on a forest in a clean atmosphere, the quality of the atmosphere in Sumava, South-Bohemia, was determined in September–October 1988. In this period the NO_X, SO₂, and aerosol concentrations were extremely low. The N-input into the forest margin amounted to 10–15 kg ha^?1 in these two months, based on a deposition velocity of 3 cm s^?1 and an average concentration of 9 μg m^?3 NH₃. The maximum hourly average ozone concentrations were found to be 50 to 100 μg m^?3. There exists a strong relation between the ambient NH₃ concentration profiles and the stable occupation. The concentration inside the stables exceeded the no-adverse-effect level for cows of 7.6 mg m^?3. This publication forms the basis for the estimation of the exposure of the forest to NH₃ and the interpretation of the observed effects as published elsewhere (Mejst?ík et al., unpublished).     

Uptake of organic emergent contaminants in spath and lettuce: an in vitro experiment

Although a myriad of organic microcontaminants may occur in irrigation waters, little attention has been paid to their incorporation in crops. In this work, a systematic approach to assess the final fate of both ionizable and neutral organic contaminants taken up by plants is described. In vitro uptake of triclosan (TCS), hydrocinnamic acid (HCA), tonalide (TON), ibuprofen (IBF), naproxen (NPX), and clofibric acid (CFA) were studied in lettuce ( Lactuca sativa L) and spath ( Spathiphyllum spp.) as model plants. After 30 days incubation, analyte depletion from the culture medium was 85-99% (lettuce) and 51-81% (spath). HCA, NPX, and CFA exhibited the highest depletion rate in both plant species. Lettuce plant tissue analysis revealed an accumulation of all compounds except for HCA. These compounds reached a peak in tissue concentration followed by a sudden drop, probably due to the plant detoxification system and analyte depletion from the culture medium. Kinetic characterization of the uptake and detoxification processes was fitted to a pseudo-first-order rate. Compounds with a carboxylic group in their structure exhibited higher uptake rates, possibly due to the contribution of an ion trap effect. Molecular weight and log K(ow) played a direct role in uptake in lettuce, as proven by the significant correlation of both properties to depletion and by the correlation of molecular weight to kinetic uptake rates.     

厌氧去除活性污泥中痕量有机污染物:15年实验研究

Knowledge of cellular metal homeostasis will provide a better understanding of the mechanisms involved in metal tolerance and hyperaccumulation in metal-hyperaccumulating plants. Energy dispersive X-ray spectrometry (EDS) was used to determine the localization of cadmium (Cd) in leaves of the Zn/Cd hyperaccumulator Picris divaricata which had a shoot Cd concentration of 565 mg kg 1 after 2 weeks of growth in solution culture supplying 10 μmol L-1 CdCl2 . The results indicated that Cd was distributed mainly in the trichomes, upper and lower epidermis and bundle sheath cells, with a relatively low level of Cd in mesophyll cells. Mesophyll protoplasts isolated from leaves remained viable after 24 h exposure to CdCl2 at a concentration up to 1 mmol L-1 , indicating their high tolerance to Cd. The intracellular Cd was visualized by staining with Leadmium Green dye, a cellular permeable Cd fluorescence probe. The results showed that the majority of protoplasts (> 82%) did not accumulate Cd, with only a minority (< 18%) showing Cd accumulation. In the Cd-accumulating protoplasts, Cd accumulation was depressed by the addition of Fe2+ , Mn2+ and the metabolic inhibitor carbonyl cyanide m-chlorophenylhydrazone (CCCP), but not by Ca 2+ or Zn2+ . Furthermore, the entire process of Cd uptake from external solution into the cytoplasm and subsequent sequestration into vacuoles was successfully recorded by confocal images. These results suggested that reduced cellular Cd accumulation and efficient Cd vacuolar sequestration in mesophyll cells might be responsible for cellular Cd tolerance and distribution in the leaves of P. divaricata.     

The effect of natural zeolites and organic fertilisers on the characteristics of degraded soils and yield of crops grown in Western Serbia

Soils with unfavourable characteristics (pronounced acidity, disturbed structure, compaction, exhaustion, tiredness, etc.) cover a considerable area of Serbia. Specific crops, the fruit ones in particular, are being grown on these soils, yielding, however, considerably lower yields. The paper presents results of two‐year studies on the effect of natural zeolites, organic fertiliser—cattle manure and mineral NPK fertiliser (15:15:15) on soil properties and fruit yield and fruit properties of strawberry and blackberry plants grown on shallow eroded vertisol. The results have shown that the chemical properties of the soil improved with the natural zeolite ‘Agrozel’ (1 kg m⁻²) + Manure (1 kg m⁻²) treatment—resulting in a 0·94‐unit acidity decrease and a 0·58% humus content increase at a 0–20 cm soil depth. Positive but less pronounced changes were also detected at greater soil depths. The strawberry and blackberry cultivation in these soils using the above substances gave rise to a yield increase. In the second year of study, strawberry and blackberry yields increased by 13·15% and 6·27%, respectively. Basic chemical properties of strawberry and blackberry fruits (soluble solids and total acid contents) were not significantly affected by zeolite and organic fertiliser additions to the soil. Copyright © 2008 John Wiley & Sons, Ltd.     

Spatial,seasonal and ecological risk assessment of organohalogenated contaminants in sediments of Swartkops and Sundays Estuaries,Eastern Cape province,South Africa

Purpose

Run-off from industrial and agricultural activities has continued to be a major source of organohalogenated contaminants (OHCs) in the environment. Swartkops (SWE) and Sundays Estuaries (SDE) located in the city of Port Elizabeth, South Africa, were selected for this study because of their proximity to industrial and agricultural activities.

Materials and methods

In this study, we determined the levels, seasonal occurrence as well as the ecological risk monitoring of 18 organochlorine pesticides (OCPs), 17 polychlorinated biphenyls (PCBs) and six polybrominated diphenyl ethers (PBDEs) in the sediments of SWE and SDE using a gas chromatograph coupled with a micro electron capture detector.

Results and discussion

HCHs, BDE-17, tri- and tetra-CBs dominated the OHC profiles in sediments of both estuaries. The respective concentration ranges of OCPs, PCBs and PBDEs in SDE sediment were 0.06–0.93 μg g^?1 dw, 0.08–1.71 μg g^?1 dw and 0.08–32.41 ng g^?1 dw while that of SWE in that order were 0.10–4.70 μg g^?1 dw, 0.07–3.80 μg g^?1 dw and 0.11–130.21 ng g^?1 dw. The high concentrations of OHCs in SWE may be due to the high usage of its surrounding area for industrial activities. The concentrations of all OHCs with exception of PCBs were higher in spring for both estuaries probably due to the heavy rain experienced during spring season. Cluster analysis and spatial distribution of OHCs indicated that samples around the Motherwell Canal in the SWE were more polluted. Total organic carbon (TOC) was strongly correlated with most OHCs in SWE revealing that TOC controls the sorption of OHCs in this estuary. Risk analysis showed that most sampling points had PCBs and HCHs concentration greater than their respective sediment quality guideline (SQGL) indicating a high risk to benthic species in SDE and SWE.

Conclusions

Samples collected from the SWE were more polluted than those collected from the SDE probably due to the extensive use of the catchment of SWE for industrial activities. In comparison with SQGL, most sampling points had PCBs and HCHs concentrations greater than their respective ERL and TEL values, indicating the potential risk to biota in SDE and SWE. Thus, an urgent need to manage and mitigate the OHCs concentrations in these estuaries is recommended.

     

Persistent organic pollutants in the natural environments of the city of Bratsk (Irkutsk Oblast): Levels and risk assessment

The contents of persistent organic pollutants (POPs)—polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs)—in the natural environments of an industrial city (Bratsk) of Irkutsk oblast have been studied. Features of the spatial and seasonal distribution of the PCBs and OCPs in the soils and the atmospheric air have been revealed. The structure of the homological and congeneric composition of the PCBs in the soils and the atmospheric air has been shown. Parameters of the carcinogenic and noncarcinogenic risks for human health from the impact of the PCBs and OCPs present in the soils and the atmospheric air have been determined.     

Developing effective sampling designs for monitoring natural resources in Alaskan national parks: An example using simulations and vegetation data

Monitoring natural resources in Alaskan national parks is challenging because of their remoteness, limited accessibility, and high sampling costs. We describe an iterative, three-phased process for developing sampling designs based on our efforts to establish a vegetation monitoring program in southwest Alaska. In the first phase, we defined a sampling frame based on land ownership and specific vegetated habitats within the park boundaries and used Path Distance analysis tools to create a GIS layer that delineated portions of each park that could be feasibly accessed for ground sampling. In the second phase, we used simulations based on landcover maps to identify size and configuration of the ground sampling units (single plots or grids of plots) and to refine areas to be potentially sampled. In the third phase, we used a second set of simulations to estimate sample size and sampling frequency required to have a reasonable chance of detecting a minimum trend in vegetation cover for a specified time period and level of statistical confidence. Results of the first set of simulations indicated that a spatially balanced random sample of single plots from the most common landcover types yielded the most efficient sampling scheme. Results of the second set of simulations were compared with field data and indicated that we should be able to detect at least a 25% change in vegetation attributes over 31 years by sampling 8 or more plots per year every five years in focal landcover types. This approach would be especially useful in situations where ground sampling is restricted by access.     

Nondestructive assessment of phytopigments in riverbed sediments by the use of instrumental color measurements

Purpose  

The quantification of phytopigments in riverbed sediments deserves further attention because it provides information about eutrophic levels, and therefore about sediment and water quality. Due to the current interest in the study of eutrophication processes, there is a need for the development of a rapid, simple, cost-effective, and nondestructive method of quantifying phytopigment content. We describe one method based on color measurements and without the need for extraction and chemical assay.     

Interaction of beta-lactoglobulin with small hydrophobic ligands as monitored by fluorometry and equilibrium dialysis: nonlinear quenching effects related to protein--protein association

Although a thorough characterization of binding parameters is essential for application of beta-lactoglobulin as a carrier for a variety of small hydrophobic ligands, the binding parameters derived in various studies using various techniques are inconsistent. The bindings of several small ligands as detected by fluorometry and equilibrium dialysis were compared. Fluorescence spectroscopy showed that beta-ionone, retinol, and fatty acid lactones all bound in the vicinity of a tryptophan residue. Retinol and fatty acid lactone competed for the same binding site. Exclusively for ligands that quench the beta-lactoglobulin fluorescence through a resonance energy transfer mechanism, fluorometry yielded a systematically higher binding affinity than equilibrium dialysis. The binding overestimation in fluorometric measurements can be explained by oligomer formation of protein, together with an underestimation of the limiting quenching level at saturating ligand concentrations due to the use of a limited set of data points.     

Chlorpyrifos transformation by aqueous chlorine in the presence of bromide and natural organic matter

The aqueous chlorination of chlorpyrifos (CP) was investigated in the presence of bromide and natural organic matter (NOM), which were identified as naturally occurring aqueous constituents that could affect CP transformation rates to the toxic product chlorpyrifos oxon (CPO). Bromide can be oxidized by chlorine to form hypobromous acid (HOBr), which was found to oxidize CP at a rate that was 3 orders of magnitude faster than was the case with chlorine: k HOBr,CP=1.14 (+/-0.21)x10(9) M(-1) h(-1) and k HOCl,CP=1.72x10(6) M(-1) h(-1), respectively. Similar to previous findings with the hypochlorite ion, hypobromite (OBr-) was found to accelerate the hydrolysis of CP and CPO: kOBr,CP=965 (+/-110) M(-1) h(-1) and kOBr,CPO=1390 (+/-160) M(-1) h(-1), respectively. Treated water from the Athens-Clarke County (ACC) water treatment plant in Athens, GA, was used in some of the experiments as a NOM source. A mechanistic model was used to adequately predict the loss of CP as well as the formation of CPO and the hydrolysis product 3,5,6-trichloro-2-pyridinol (TCP) in the presence of the ACC water.     

Stabilization mechanisms of organic matter in four temperate soils: Development and application of a conceptual model

Based on recent findings in the literature, we developed a process‐oriented conceptual model that integrates all three process groups of organic matter (OM) stabilization in soils namely (1) selective preservation of recalcitrant compounds, (2) spatial inaccessibility to decomposer organisms, and (3) interactions of OM with minerals and metal ions. The model concept relates the diverse stabilization mechanisms to active, intermediate, and passive pools. The formation of the passive pool is regarded as hierarchical structured co‐action of various processes that are active under specific pedogenetic conditions. To evaluate the model, we used data of pool sizes and turnover times of soil OM fractions from horizons of two acid forest and two agricultural soils. Selective preservation of recalcitrant compounds is relevant in the active pool and particularly in soil horizons with high C contents. Biogenic aggregation preserves OM in the intermediate pool and is limited to topsoil horizons. Spatial inaccessibility due to the occlusion of OM in clay microstructures and due to the formation of hydrophobic surfaces stabilizes OM in the passive pool. If present, charcoal contributes to the passive pool mainly in topsoil horizons. The importance of organo‐mineral interactions for OM stabilization in the passive pool is well‐known and increases with soil depth. Hydrophobicity is particularly relevant in acid soils and in soils with considerable inputs of charcoal. We conclude that the stabilization potentials of soils are site‐ and horizon‐specific. Furthermore, management affects key stabilization mechanisms. Tillage increases the importance of organo‐mineral interactions for OM stabilization, and in Ap horizons with high microbial activity and C turnover, organo‐mineral interactions can contribute to OM stabilization in the intermediate pool. The application of our model showed that we need a better understanding of processes causing spatial inaccessibility of OM to decomposers in the passive pool.     

The dioRAMA project: assessment of dioxin-like activity in sediments and fish (Rutilus rutilus) in support of the ecotoxicological characterization of sediments

Introduction

Given the complex interactions of re-suspension processes and bioavailability of sediment-bound pollutants such as dioxin-like chemicals, there is need for a better integrative understanding of the cause–effect relationship of these pollutants. Currently, the majority of studies investigating potential risks of these chemicals only focus on characterizing sediment extracts via in vitro bioassays, thereby disregarding bioavailability, uptake, metabolism, and elimination rates of these compounds in vivo. To determine to which extent mechanism-specific effects in vitro reflect possible adverse effects in vivo, the research project dioRAMA, involving partnership between the Institute for Environmental Research of RWTH Aachen University and the Department Biochemistry/Ecotoxicology of the German Federal Institute of Hydrology, was established.

Methods

Animals from an elevated trophic level—common roach (Rutilus rutilus)—will be exposed to sediments from two major German rivers. Exposure will be performed in a system that enables a concurrent monitoring of environmental parameters. In parallel, in vitro studies will be conducted to determine dioxin-like potentials of sediment and fish extracts from the in vivo exposure experiments using different cell lines with varying endpoints. Moreover, extract fractionation procedures, using the strategy of effect-directed analysis, will enable the detection of specific contaminant groups responsible for the biological activity observed.

Conclusion

A closer interconnection between applied ecotoxicological science and regulatory needs will facilitate the improved assessment of dioxin-like compounds in sediment and biota. Consequently, this will enable their application in sediment management programs, which is one of the main goals of the dioRAMA project.     

Fractionation of copper and uranium in organic and conventional vineyard soils and adjacent stream sediments studied by sequential extraction

Purpose

Particularly in organic viticulture, copper compounds are intentionally released into the environment as fungicide, whereas uranium originates from conventional phosphate fertilization. Both activities contribute to the metal contamination in wine-growing areas. This pilot study aimed to better understand how soil properties influence the presence and environmental fate of copper and uranium with respect to viticultural management.

Materials and methods

We characterized metal binding forms, i.e., their association with different soil constituents, in organically and conventionally cultivated vineyard soils and adjacent upstream and downstream sediments. The available metal fraction and the fractions associated with manganese oxides, organic matter, iron oxides, and total contents were extracted sequentially.

Results and discussion

Total soil copper ranged from 200 to 1600 mg kg^?1 with higher contents in topsoil than subsoil. The majority of copper (42–82%) was bound to soil organic matter. In all fractions, copper contents were up to 2-fold higher in organic than in conventional vineyards, whereas the sediment concentrations were independent of the adjacent viticultural management. A net increase of copper in downstream sediments was found only when water-extractable organic carbon (WEOC) in an adjacent vineyard was elevated. With 11 ± 1 mg kg^?1, total uranium was 25% higher in conventional than in organic vineyard soils. Its affinity to iron or WEOC potentially rendered uranium mobile leading to a substantial discharge to downstream sediments.

Conclusions

Translocation of copper and uranium from vineyards into adjacent stream sediments may rather be attributed to WEOC and iron contents than the viticultural management. Follow-up studies should scrutinize the processes driving metal availability and transport as well as their interaction at the aquatic–terrestrial interface.

     

Stabilization of organic matter in temperate soils: mechanisms and their relevance under different soil conditions – a review

Mechanisms for C stabilization in soils have received much interest recently due to their relevance in the global C cycle. Here we review the mechanisms that are currently, but often contradictorily or inconsistently, considered to contribute to organic matter (OM) protection against decomposition in temperate soils: (i) selective preservation due to recalcitrance of OM, including plant litter, rhizodeposits, microbial products, humic polymers, and charred OM; (ii) spatial inaccessibility of OM against decomposer organisms due to occlusion, intercalation, hydrophobicity and encapsulation; and (iii) stabilization by interaction with mineral surfaces (Fe‐, Al‐, Mn‐oxides, phyllosilicates) and metal ions. Our goal is to assess the relevance of these mechanisms to the formation of soil OM during different stages of decomposition and under different soil conditions. The view that OM stabilization is dominated by the selective preservation of recalcitrant organic components that accumulate in proportion to their chemical properties can no longer be accepted. In contrast, our analysis of mechanisms shows that: (i) the soil biotic community is able to disintegrate any OM of natural origin; (ii) molecular recalcitrance of OM is relative, rather than absolute; (iii) recalcitrance is only important during early decomposition and in active surface soils; while (iv) during late decomposition and in the subsoil, the relevance of spatial inaccessibility and organo‐mineral interactions for SOM stabilization increases. We conclude that major difficulties in the understanding and prediction of SOM dynamics originate from the simultaneous operation of several mechanisms. We discuss knowledge gaps and promising directions of future research.