Determining tolerance limits for restoration and phytoremediation with Spartina patens in crude oil-contaminated sediment in greenhouse

Oil spills may detrimentally damage sensitive coastal habitats, such as coastal wetlands. Successful restoration of oiled habitats primarily depends on the tolerance of vegetation transplants to oil. In this study, tolerance limits of the dominant coastal brackish marsh plant Spartina patens to South Louisiana crude (SLC) oil and its phytoremediation effectiveness on petroleum hydrocarbons in wetland sediments were investigated in the greenhouse environment. Spartina patens was transplanted into brackish marsh sediments contaminated with SLC oil at concentrations of 0, 40, 80, 160, 320, 640 and 800 mg SLC oil g^?1 dry sediment. High oil concentrations adversely affected plant stem density, aboveground biomass and belowground biomass even one year after transplantation. At the 320 mg g^?1 oil dosage, plant belowground biomass was significantly lower than the control although aboveground variables were not significantly different from the control. All plant parameters mentioned above at the 640 mg g^?1 oil dosage were less than 50% of the control. Spartina patens did not survive the 800 mg g^?1 oil dosage. The tolerance limit of S. patens to SLC was estimated about 320 mg oil g^?1 dry sediment. In addition, S. patens transplants enhanced oil degradation in the sediment; concentrations of residual total petroleum hydrocarbons (TPH) in the sediments vegetated by S. patens were significantly lower than those of un-vegetated sediments for both the surface and subsurface sediment at the 40 and 160 mg g^?1 SLC oil dosages. Decreases in the concentrations of polycyclic aromatic hydrocarbons (PAHs) further demonstrated the capacity of S. patens to phytoremediate residual oil; residual total targeted PAHs in the phytoremediation treatment were less than 20% of the un-vegetated treatment at the 40 mg g^?1 oil dosage. These results demonstrated the potential of phytoremediation with S. patens to simultaneously restore and remediate petroleum-contaminated coastal marsh habitats.     

Remediation of contaminated soil using soil washing and biopile methodologies at a field level

Background, Aims and Scope  An out-of-service oil distribution and storage station (ODSS), which operated from 1966 to 2000 in Mexico, is contaminated mainly by gasoline and diesel, showing the presence of methyl-tert-butyl-ether, benzene, toluene, ethyl benzene, and xylenes. Nine of the 16 polycyclic aromatic hydrocarbons were found, as well as Fe, Pb, V, and Zn. The health risk assessment suggested the necessity of reducing of three PAHs [benzo(a)anthracene, benzo(a)pyrene, and benzo-(b)fluoranthene], and vanadium. The aim of this work is to show that soil washing (on-site) and biopiles are excellent remediation methodologies to treat soils contaminated with petroleum derivates and metals. Applying them, it is possible to reach the goal value of 2,000 mg TPH/kg in a few months, as requested by Mexican legislation. Methods  More than 140 m³ were excavated from the ODSS. Three soil-washing dishes were built. 1540 m³ were treated by soil washing using a nonionic surfactant. A 100 m³ biopile was built to study the system capabilities in the biodegradation of around 4,500 mg/kg of TPH using the autochthonous microflora. Results and Discussion  The soil washing, average TPH-removal value was 83%, but values up to ca. 93% were observed. Removal values resulted in a function of the TPH initial values. Biopile (100 m³) worked during 66 days, reaching a TPH-removal value of 85%. At the end of the processes, no PAHs were detected. The contaminated soil was treated successfully, reaching the legislation limits (TPH values under 2,000 mg/kg, and a significant reduction in PAH concentrations). Conclusion and Recommendation  Both systems are suitable for remediation purposes, achieving high removal efficiencies at short and medium stages. It is highly recommended to proceed with soil washing studies, identifying new products, and mixtures, which could reduce costs and assure optimum operation.     

生物表面活性剂强化微生物修复多环芳烃污染土壤的初探

通过温室盆栽实验,单独或联合接种多环芳烃专性降解菌(DB)和添加生物表面活性剂-鼠李糖脂(RH),研究了生物表面活性剂强化微生物修复多环芳烃(PAHs)长期污染土壤的效果。结果表明,添加RH和接种DB能明显促进土壤中PAHs总量和各组分PAHs的降解。经过90 d培养后,添加RH、DB和RH+DB处理的PAHs的降解率分别为21.3%、32.6%、36.0%,较对照分别提高了333.0%、563.3%、633.0%。此外,随着苯环数的增加,土壤中15种PAHs平均降解率逐渐降低。同时也发现DB、RH+DB处理土壤中脱氢酶活性、多酚氧化酶活性和PAHs降解菌数量显著高于CK、RH处理,但是CK与RH处理没有显著差异,说明DB、RH在促进土壤中PAHs的降解方面有不同的机制。     

石油污染土壤鞘氨醇单胞菌遗传多样性16S rDNA-PCR-DGGE分析

鞘氨醇单胞菌是降解多环芳烃(PAHs)的重要功能微生物。然而,采用属特异引物直接从PAHs污染土壤中检测鞘氨醇单胞菌进而研究鞘氨醇单胞菌在污染土壤中的多样性、种群结构及其与PAHs污染的关系鲜有报道。本研究自行设计鞘氨醇单胞菌属特异性引物,通过16S rDNA-PCR-DGGE技术对沈抚灌区石油污染土壤鞘氨醇单胞菌遗传多样性进行了研究。结果表明,自行设计的鞘氨醇单胞菌属引物732f-982r能够特异、灵敏的从环境样品中检出鞘氨醇单胞菌。当沈抚灌区原位污染土壤的PAHs浓度小于5 mg kg-1时,鞘氨醇单胞菌多样性随着PAHs浓度的增加而增加;而初始PAHs浓度高的实验室模拟实验土壤,其鞘氨醇单胞菌多样性较低。鞘氨醇单胞菌种群结构受污染土壤总石油烃(TPH)含量的影响,TPH含量接近的土壤,鞘氨醇单胞菌的群落结构较为相似。     

有机酸对污染土壤中镉释放的影响

There is limited information on the release behavior of heavy metals from natural soils by organic acids. Thus, cadmium release, due to two organic acids (tartrate and citrate) that are common in the rhizosphere, from soils polluted by metal smelters or tailings and soils artificially contaminated by adding Cd were analyzed. The presence of tartrate or citrate at a low concentration (≤ 6 mmol L^-1 for tartrate and ≤ 0.5 mmol L^-1 for citrate) inhibited Cd release, whereas the presence of organic acids in high concentrations (≥ 2 mmol L^-1 for citrate and ≥ 15 mmol L^-1 for tartrate) apparently promoted Cd release. Under the same conditions, the Cd release in naturally polluted soils was less than that of artificially contaminated soils. Additionally, as the initial pH rose from 2 to 8 in the presence of citrate, a sequential valley and then peak appeared in the Cd release curve, while in the presence of tartrate the Cd release steadily decreased. In addition, Cd release was clearly enhanced as the electrolyte concentration of KNO₃ or KCl increased in the presence of 2 mmol L^-1 tartrate. Moreover, a higher desorption of Cd was shown with the KCl electrolyte compared to KNO₃ for the same concentration levels. This implied that the bioavailability of heavy metals could be promoted with the addition of suitable types and concentrations of organic acids as well as reasonable field conditions.     

Immobilization of cadmium in simulated contaminated soils using thermal-activated serpentine

ABSTRACT

The thermal-activated serpentine prepared by heating natural serpentine at different temperatures was used to immobilize cadmium (Cd) in simulated contaminated soils. The results showed that the increasing soil pH induced by adding serpentine was primarily responsible for reducing the content of TCLP-Cd (toxicity characteristic leaching procedure-Cd) in soil. Furthermore, adding thermal-activated serpentine could promote the transformation from exchangeable form of Cd in soil to low bioavailable Cd (Fe-Mn oxides, carbonate, and residual form) by surface adsorption and surface precipitation, and then reduced the bioavailability of Cd in soil. Under the same treatment condition, adding S700 (serpentine activated at 700°C) exhibited better performance to immobilization of Cd, and it could reduce exchangeable Cd by 23.76~36.49%, and increase carbonate, Fe-Mn oxide, and residual form of Cd by 6.03~8.03%, 6.05~8.35%, and 11.17~19.58%, respectively. These results indicated that thermal-activated serpentine would be the great potential for immobilization of Cd in soil.     

采用通气堆沤对石油烃污染土壤进行生物修复

Laboratory simulation studies and a composting pilot study were conducted to evaluate the capacity of three strains of fungi, indigenous fungus Fusarium sp. and Phanerochaete chrysosporium and Coriolus Versicolor, to remediate petroleum-contaminated soils. In laboratory, the fungi were inoculated into a liquidculture medium and the petroleum-contaminated soil samples for incubation of 40 and 50 days 5 respectively. In the 200-day pilot study, nutrient contents and moisture were adjusted and maintained under aerobiccondition in composting units using concrete container (118.5 cm × 65.5 cm × 12.5 cm) designed specially for this study. The laboratory simulation results showed that all the three fungi were effective in degrading petroleum in the liquid culture medium and in the soil. At the end of both the laboratory incubations, the degradation rates by Phanerochaete chrysosporium were the highest, reaching 66% after incubation in liquid culture for 50 days. This was further demonstrated in the composting pilot study where the degradation rate by P. chrysosporium reached 79% within 200 days, higher than those of the other two fungi (53.1% and 46.1%), indicating that P. chrysosporium was the best fungus for bioremediation of soil contaminated with petroleum. Further research is required to increase degradation rate.     

Evaluation of two bacterial delivery systems for in-situ remediation of PAH contaminated sediments

Intention, Goal and Background  Contaminated sediments represent a significant, worldwide environmental problem since they contain a mixture of different xenobiotics and heavy metals. The presence of mixed contamination presents a unique set of obstacles for remediation efforts. Often sediment remediation occurs as an ex-situ application (i.e., after dredging) in an attempt to minimize some of the problems. However, dredging poses it’s own issues. It does not address contaminated water and often material is not completely removed thereby leaving a long-term residual contamination source in the waterway. Objective  The potential of bio remediation to treat sediments contaminated with polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, and heavy metals was addressed. The primary objective was to assess two delivery mechanisms for microbial inoculation to facilitate in-situ remediation of PAH contaminated sediments. Methods  Simulated river beds were constructed to mimic the Mahoning River. Contaminated sediment from the river was added to each reactor at a uniform depth, followed by the addition of river water. Fifteen inoculation points were used in each simulated river bed to ensure adequate microbial populations. One tank was inoculated with an acclimated bacteria solution as a free suspension. The other tank was inoculated with an attached growth biofilm system. Sediment samples were taken throughout the experiment and the percent PAH degradation determined. Water characteristics (DO, pH, bacterial activity, etc.) were also tracked as corroborating evidence. Results and Discussion  The monitoring sites indicated that an attached growth system was more effective, and achieved a 99% PAH degradation efficiency at some of the sampling sites. Tracking individual PAH compounds also indicated a higher overall microbial activity with the attached growth system. This activity was evident by the formation and subsequent biodegradation of lower molecular weight degradation byproducts. However, more of the sediment area was treated by the free suspension inoculum due to the ease of microbial migration. Conclusions  The applicability of using an aerobic microbial consortium composed ofMycobacterium sp., Pseudomonas aeruginosa, andPseudomonas flourescens to treat contaminated sediment was demonstrated. In addition, it was found that introducing the consortium as an attached growth was more effective than when delivered as a free suspension. Recommendation and Outlook  The results demonstrated that the consortium was effective at treating the PAHs present in the contaminated soil. An additional study to evaluate the consortium’s effectiveness at remediating the PCB present in the sediment is warranted. Optimization of the consortium-nutrient combination could enable a treatment approach to effective for all the organic contaminants present. Although this would not address the heavy metals present in the sediment, it would afford a great opportunity at remediating a severely contaminated sediment system.     

丛枝菌根作用下土壤中多环芳烃的残留及形态研究

采用盆栽试验方法,以苊为多环芳烃(PAHs)代表物,研究了丛枝菌根(AM)作用下土壤中 PAHs 的残留及形态.供试污染土壤中苊的起始浓度为 35.0 mg/kg.结果表明,AM作用下土壤中苊总残留量明显降低;接种摩西球囊霉菌Glomus mosseae或幼套球囊霉菌Glomus etunicatum后,供试两个污染土样中苊总残留降解率达32.7%～45.2%,比未接种对照高 6.8%～9.8%.有机溶剂提取态是土壤中苊残留的主要部分,AM 作用促进了苊各形态之间的转化;接种AM后土壤 1、2 中苊可脱附态和有机溶剂提取态残留量分别比对照降低了17.0%～37.8% 和 5.4%～26.6%,而结合态残留量比对照增加了12.2%～89.5%.AM 作用能降低土壤中苊可提取态残留含量;但培养55 天后土壤中仍有 65.7%～81.7% 苊属于可提取态残留,对生物有毒害风险.     

丛枝菌根对芘污染土壤修复及植物吸收的影响

采用温室盆栽试验方法,研究了两种丛枝菌根真菌Glomus mosseae和 Glomus etunicatum对三叶草(Trifolium subterraneum L.)和辣椒（Capsicum annuum L.）修复芘污染土壤的影响。供试土样中芘初始浓度为0 ~ 75.18 mg/kg。结果表明,接种AMF可促进供试植物对土壤中芘的吸收,并且显著提高三叶草根的芘含量、根系富集系数、根和茎叶的芘积累量,但对辣椒根和茎叶芘含量、根系富集系数的影响不显著,这主要与植物的菌根侵染率和“菌根依赖度”不同有关。接种AMF土壤中芘的削减率高于普通植物修复,但植物吸收积累对修复的贡献率小于0.2%;因此推测,AM作用下良好的根际环境对土壤微生物数量和活性的提高、进而对土壤中芘降解的促进可能是菌根修复的主要机理。     

产漆酶真菌筛选及其对PAHs污染土壤修复的初步研究

真菌漆酶可以高效转化多环芳烃(PAHs),因此,产漆酶真菌在PAHs污染土壤修复中极具应用前景。根据漆酶可将愈创木酚氧化为红色物质的特性,成功从土壤中筛选出一株能够分泌漆酶的真菌菌株F-1,初步鉴定该菌为疣孢漆斑菌(Myrothecium verrucaria)。通过Plackett-Burman试验对菌株F-1的产酶能力进行了分析,发现特定培养条件组合可将其酶活提高近300倍,达5628 U L-1,表明F-1的漆酶活性受到环境条件的显著影响。应用菌株F-1对PAHs污染土壤进行了初步修复研究,结果表明,接种F-1对菲、荧蒽、芘、苯并(a)蒽、屈、苯并(b)荧蒽、苯并(k)荧蒽、苯并(a)芘、二苯并(a,h)蒽、苯并(g,h,i)苝、茚苯(1,2,3-cd)芘等11种PAHs均有不同程度的降解,提示产漆酶真菌在PAHs污染土壤修复中的应用潜力。     

A characterization of the soils and sediments in contaminated sites and rivers using petroleum biomarker compounds

Journal of Soils and Sediments - The objective of this study is to reveal the presence of petroleum biomarkers in sediments of contaminated sites and to prove the existence of these compounds in...     

Spectroscopic Determination of Soil Organic Carbon and Total Nitrogen Content in Pasture Soils

To explore a convenient and efficient approach for determining the content of soil organic carbon (SOC) and total nitrogen (TN), this study focused on capturing the features value of SOC and TN by applying the method of wavelet analysis and wavelet transformation. The soil used in the study was sampled from the pastures in Fukang City of Xinjiang Uygur Autonomous Region, China. The soil samples were tested by using a combined approach of chemical analysis and spectroscopy measurements. It was found that reflectance at 400–2500 nm was more strongly correlated to SOC than to TN. The maximum negative r values between reflectance and SOC + TN at 2309 nm was –0.81 (P < 0.01), and SOC/TN at 1693 was –0.48 (P < 0.05). The maximum correlation coefficient between SOC, TN, and wavelet coefficient was more than 0.96 compared to the relationship among SOC, TN, and spectral reflectance. By using continuous wavelet transformation (CWT), it was found that the maximum correlation coefficients were 0.981 at 2328 nm of scale 13 for SOC and 0.968 at 1741 nm of scale 6 for TN. These results also suggested that wavelet analysis was a better method for capturing the absorption features of soil properties and determining SOC and TN content.     

气相色谱-质谱法分段测定土壤中的可提取总石油烃

本文建立了用气相色谱-质谱法分段分析土壤中可提取总石油烃的检测方法,并对该方法进行了质量控制研究。土壤中的总石油烃的检测范围是C8(C7.6)~C34(C34.01)。用索氏提取,柱层析分离方法进行前处理,用C8(C7.6),C10(C10.1),C12(C11.7),C16(C15.5),C21(C20.8),C34(C34.01)标准品分别作为C8~C10(C7.6~C10.1),C10~C12(C10.1~C11.7),C12~C16(C11.7~C15.5),C16~C21(C15.5~C20.8),C21~C34(C20.8~C34.01)每段馏分的"替代物"定量,将C8~C34之间所有波峰面积分段积分,以"替代物"的线性关系计算每段馏分的浓度。该方法的质控结果:脂肪烃:相关系数为0.990 3~0.999 8;最低检出限为0.011~0.373 ng/μl;回收率为50.3%~109.3%;相对标准偏差为1.5%~11.3%;芳香烃:相关系数为0.991 3~0.997 6;最低检出限为0.004~0.047 ng/μl;回收率为53.6%~107.7%;相对标准偏差为3.2%~12.2%。本方法检测结果能准确反映土壤的污染程度并有助于生物毒性计算。     

Changes in Polycyclic Aromatic Hydrocarbons (PAHs) and Soil Biological Parameters in a Revegetated Coal Mine Spoil

Coal mining leads to severe land degradation and creates huge amounts of mine spoil. Coal mine spoil contains toxic polycyclic aromatic hydrocarbons (PAHs) derived from coal, which can be alleviated through revegetation with suitable tree species. The present study was aimed at evaluating the impact of different tree species (Albizia lebbeck , Cassia siamea , Delonix regia , and Dalbergia sissoo ) on the quality of coal mine spoil and changes in PAH concentration. Soil samples were collected from the revegetated coalmine overburden dumps of Jharia coalfield, Dhanbad, India and analysed by GC‐MS for 16 priority PAHs and soil quality parameters were analyzed by standard analytical protocols. Reclamation improved the biological properties of the mine spoil: microbial biomass (+59–176%), dehydrogenase activity (+46–198%), fluorescein diacetate hydrolase activity (+104–127%), phenol oxidase activity (+150–250%), and peroxidase activity (+93–181%). PAH concentration in revegetated mine spoil ranged from 0 · 51 to 1 · 35 mg kg⁻¹, with a significance reduction in total as well as individual PAHs. For individual tree species, total PAH reduction decreased in the order: C. siamea (81 · 6%) > A. lebbeck (55 · 6%) > D. regia (51 · 9%) > D. sissoo (51 · 5%). Correlation analysis showed significant association between the degradation of PAHs and soil biological properties of revegetated site. Microbial biomass carbon and soil enzymes were negatively correlated with PAH content in the mine spoil. But microbial stress indicators like respiration/microbial carbon ratio were not correlated, which revealed no adverse effect of PAH on soil microbes. Principal component analysis revealed that most of the biological parameters were closely associated with the degradation of low molecular weight PAHs. Copyright © 2016 John Wiley & Sons, Ltd.     

Using pXRF and vis-NIR spectra for predicting properties of soils developed in loess

Visible near-infrared (vis-NIR) and portable X-ray fluorescence (pXRF) spectrometers have been increasingly utilized for predicting soil properties worldwide. However, only a few studies have focused on splitting the predictive models by horizons to evaluate prediction performance and systematically compare prediction performance for A, B, and combined A+B horizons. Therefore, we investigated the performance of pXRF and vis-NIR spectra, as individual or combined, for predicting the clay, silt, sand, total carbon (TC), and pH of soils developed in loess, and compared their prediction performance for A, B, and A+B horizons. Soil samples (176 in A horizon and 172 in B horizon) were taken from Mollisols and Alfisols in 136 pedons in Wisconsin, USA and analyzed for clay, silt, sand, pH, and TC. The pXRF and vis-NIR spectrometers were used to measure the pXRF and vis-NIR soil spectra. Data were separated into calibration (n=244, 70%) and validation (n=104, 30%) datasets. The Savitzky-Golay filter was applied to preprocess the pXRF and vis-NIR spectra, and the first 10 principal components (PCs) were selected through principal component analysis (PCA). Five types of predictor, i.e., PCs from vis-NIR spectra, pXRF of beams at 0-40 and 0-10 keV (XRF40 and XRF10, respectively) spectra, combined XRF40 and XRF10 (XRF40+XRF10) spectra, and combined XRF40, XRF10, and vis-NIR (XRF40+XRF10+vis-NIR) spectra, were compared for predicting soil properties using a machine learning algorithm (Cubist model). A multiple linear regression (MLR) model was applied to predict clay, silt, sand, pH, and TC using pXRF elements. The results suggested that pXRF spectra had better prediction performance for clay, silt, and sand, whereas vis-NIR spectra produced better TC and pH predictions. The best prediction performance for sand (R²=0.97), silt (R²=0.95), and clay (R²=0.84) was achieved using vis-NIR+XRF40+XRF10 spectra in B horizon, whereas the best prediction performance for TC (R²=0.93) and pH (R²=0.79) was achieved using vis-NIR+XRF40+XRF10 spectra in A+B horizon. For all soil properties, the best MLR model had a lower prediction accuracy than the Cubist model. It was concluded that pXRF and vis-NIR spectra can be successfully applied for predicting clay, silt, sand, pH, and TC with high accuracy for soils developed in loess, and that spectral models should be developed for different horizons to achieve high prediction accuracy.     

多环芳烃污染土壤的植物-微生物联合修复初探

在温室盆栽条件下,通过种植紫花苜蓿单独或联合接种菌根真菌(Glomus caledonium L.)(AM)和多环芳烃专性降解菌(DB),研究了利用植物-微生物强化修复多环芳烃(PAHs)长期污染土壤的效果。试验结果表明,接种菌根真菌和PAHs专性降解菌能促进紫花苜蓿的生长和土壤中PAHs的降解。经过90天修复试验,种植紫花苜蓿接种AM、DB和DB+AM处理的PAHs的降解率分别为47.9%、49.6%、60.1%,均高于只种植紫花苜蓿的对照处理(CK)(21.7%)。另外,随着PAHs苯环数的增加,其平均降解率逐渐降低,但是接种PAHs专性降解菌能够提高4环和5环PAHs的降解率。同时也发现土壤中脱氢酶活性和PAHs降解菌数量越高的处理,土壤PAHs的降解率也越高,这也是种植紫花苜蓿接种微生物能够有效促进土壤PAHs降解的原因。     

淀粉对无芒雀麦修复煤矿区多环芳烃长期污染土壤的影响

采用温室盆栽试验,以无芒雀麦(W)为修复植物,研究淀粉(D)不同剂量与无芒雀麦组合对煤矿区多环芳烃(PAHs)长期污染农田土壤修复的影响。结果表明,在土壤中添加淀粉剂量D1、D2培养3个月后,显著促进了土著微生物对煤矿区长期污染农田土壤PAHs的降解。D1、D2处理土壤中16种PAHs总量降解率(16.82%,19.06%)分别比对照CK(11.12%)提高了51.26%和71.40%,尤其对6环PAHs的降解增效最为突出。D2处理对6环PAHs的降解达最高,为37.05%,比CK处理提高了241.01%,且为D1处理的1.77倍。在污染土壤中添加淀粉并种植无芒雀麦(D1+W,D2+W)后,与对照CK、淀粉(D)和种植无芒雀麦单一处理(W)相比,土壤中16种PAHs总量降解率有了明显增加,D1+W与D2+W处理下16种PAHs降解率分别为26.26%和28.39%;在PAHs不同环数中对5,6环PAHs的修复效果提升最为明显,对其它环数PAHs降解效果提升不显著,其中5环和6环PAHs降解率在D2+W组合处理下达到最高,为48.63%和58.32%,比CK处理提高了110.36%和436.82%,比无芒雀麦单一处理提高了27.50%和47.77%。从土壤酶活性角度,淀粉、无芒雀麦单一处理及其组合下的土壤过氧化氢酶活性差异不明显,但均显著高于对照CK处理;无芒雀麦对多酚氧化酶活性有明显的激活作用,且与淀粉组合进一步显著提升了该酶的活性,与D1+W与D2+W组合下的5,6环PAHs降解率达最高相一致。综上,利用淀粉与无芒雀麦的优化组合形式能明显提升煤矿区5,6环PAHs长期污染农田土壤的修复效果,可以作为该区污染土壤修复治理的一种选择。     

有机溶剂对有机氯农药污染场地土壤淋洗修复效用研究

Problems associated with organochlorine pesticide (OCP)-contaminated sites in China have received wide attention. To solve such problems, innovative ex-situ methods of site remediation are urgently needed. We investigated the feasibility of the extraction method with different organic solvents, ethanol, 1-propanol, and three fractions of petroleum ether, using a soil collected from Wujiang (WJ), China, a region with long-term contamination of dichlorodiphenyltrichloroethanes (DDTs). We evaluated different influential factors, including organic solvent concentration, washing time, mixing speed, solution-to-soil ratio, and washing temperature, on the removal of DDTs from the WJ soil. A set of relatively better parameters were selected for extraction with 100 mL L 1 petroleum ether (60-90℃): washing time of 180 min, mixing speed of 100 r min 1 , solution-to-soil ratio of 10:1, and washing temperature of 50℃. These selected parameters were also applied on three other seriously OCP-polluted soils. Results demonstrated their broad-spectrum effectiveness and excellent OCP extraction performance on the contaminated soils with different characteristics.     

某氮肥厂场地土壤PAHs污染特征研究

采用现场采样及室内测试方法对广州某氮肥厂原料车间和油库区土壤中16种优控多环芳烃（PAHs）的含量进行调查研究,分析了EPAHs含量及其组成特征和垂直分布特征,并在此基础上进行了源解析。结果表明,分析样品中∑PAHs范围在10-7795μg·kg,原料车间土壤中的∑PAHs小于油库区土壤中的,菲、芘、荧蒽、并（b）荧蒽、苯并（a）芘为主要污染物;油库土壤0-40cm的样品中16种PAHs均有检出,∑PAHs和单体分布基本一致;原料车间土壤∑PAHs和单体浓度随着地面深度的增加而减少。通过对单组分比值（菲／蒽,荧蒽／芘）的分析可以看出油库区土壤中PAHs来源于石油和燃烧源,而原料车间污染源主要为燃烧源。