多环芳烃污染土壤的生物修复

综述了土壤环境中多环芳烃的来源、归宿、生物转化机理、影响因素及生物修复技术研究进展,提出了利用生物技术治理土壤环境中多环芳烃的思路及方法。     

多环芳烃污染土壤的可行处理技术

本文讨论了处理多环芳烃(PAHs)污染土壤的可行技术。土壤冲洗可解决部分问题;土壤焚烧可高效地去除PAHs,但是通常这种方法会导致二次污染;含PAHs土壤的生物处理得到了广泛的关注,因为生物处理没有副产品,可以在没有副作用的情况下消除污染物。PAHs的土壤污染问题远没有解决,然而,生物处理已经给我们提供了解决问题的希望。     

皂角苷增强洗脱复合污染土壤中多环芳烃和重金属的作用及机理

通过增溶实验和土壤洗脱实验,研究了一种生物表面活性剂——皂角苷（saponin）对多环芳烃-重金属复合污染土壤的洗脱作用及机理。结果表明,皂角苷对菲、芘等多环芳烃有极强的增溶作用,当皂角苷浓度为0.04%时,菲、芘在液相中的表观溶解度分别增大了约22倍和128倍,因而皂角苷能显著增强多环芳烃污染土壤中菲、芘的洗脱,洗脱效率最大分别可达84.1%和81.4%,增大了约2倍和17倍。皂角苷可与重金属离子形成水溶性的络合物,从而增强洗脱重金属污染土壤中的Zn^2＋和Cd^2＋,在皂角苷浓度为0.4%时,Zn^2＋、Cd^2＋的洗脱效率分别可达93.0%和79.4%,增大了约75倍和8倍。皂角苷可同时洗脱多环芳烃-重金属复合污染土壤中的菲、芘和Zn^2＋、Cd^2＋,洗脱效率分别达87.6%、83.5%和92.3%、78.6%,重金属的存在略增大了皂角苷对菲、芘等多环芳烃的洗脱效率,但多环芳烃对Zn^2＋、Cd^2＋的洗脱效率没有明显影响。皂角苷可同时增强洗脱复合污染土壤中的多环芳烃和重金属,从而为多环芳烃-重金属复合污染土壤的修复奠定基础。     

海洋细菌生物膜用于生物修复陆地生态系统中土壤多环芳烃污染

Polycyclic aromatic hydrocarbons(PAHs) in soil retain for a quite long period due to their hydrophobicity and aggregation properties. Biofilm-forming marine bacterial consortium(named as NCPR), composed of Stenotrophomonas acidaminiphila NCW702,Alcaligenes faecalis NCW402, Pseudomonas mendocina NR802, Pseudomonas aeruginosa N6P6, and Pseudomonas pseudoalcaligenes NP103, was used for the bioremediation of PAHs in a soil microcosm. Phenanthrene and pyrene were used as reference PAHs. Parameters that can affect PAH degradation, such as chemotaxis, solubility of PAHs in extracellular polymeric substances(EPS), and catechol2,3-dioxygenase(C23O) activity, were evaluated. P. aeruginosa N6P6 and P. pseudoalcaligenes NP103 showed chemotactic movement towards both the reference PAHs. The solubility of both the PAHs was increased with an increase in EPS concentration(extracted from all the 5 selected isolates). Significantly(P 0.001) high phenanthrene(70.29%) and pyrene(55.54%) degradation was observed in the bioaugmented soil microcosm. The C23O enzyme activity was significantly(P 0.05) higher in the bioaugmented soil microcosm with phenanthrene added at 173.26 ± 2.06 nmol min~(-1) mg~(-1) protein than with pyrene added at 61.80 ± 2.20 nmol min~(-1) mg~(-1) protein. The C23O activity and gas chromatography-mass spectrometer analyses indicated catechol pathway of phenanthrene metabolism. However, the metabolites obtained from the soil microcosm added with pyrene revealed both the catechol and phthalate pathways for pyrene degradation.     

高分子量多环芳烃污染土壤的菌群修复研究

多环芳烃(Polycyclic aromatic hydrocarbons,PAHs)是环境中普遍存在的一类有机污染物,由于其在土壤中的半衰期较长和致癌、致畸形、致突变的性质而受到人们的重视。微生物是生态系统中最重要的分解者,对PAHs具有较强的分解代谢能力和较高的代谢速率。通常认为,PAHs的环数越高,越难被微生物降解利用[1]。高分子量PAHs(三环以上的PAHs)具有更高的毒性和亲脂性,更难被微生物降解。环境中PAHs通常以多种组分同时存在,呈现其复合污染现象,增加了微生物降解的难度。因此,筛选能够同时降解多种高分子量PAHs的微生物,具有重要的现实意义。目前,越来越多的国内外学者采用微     

多环芳烃污染土壤的微生物与植物联合修复研究进展

通过对江西省余江县洪湖乡历史资料的分析,结合农户经济行为调查,阐述了典型红壤丘陵区农作系统的演变过程及其特征,并且针对农业生产中存在的问题,提出解决对策。分析结果表明,20世纪50年代以前,长江中下游流域农作系统的演变过程可以分为丘陵和河谷砂性水稻土的游垦系统-雨季水稻耕作系统-水旱轮作系统3个阶段。20世纪50年代以后,江西省余江县洪湖乡农作系统的演变分为农业革命和现有系统2个阶段,粮食安全驱动和生存型经济福利驱动是其演变的主要驱动力。80年代以来,随着经济的发展,一部分农作系统演变为可持续再生产型,但需要较高的劳力和资金投入,并且有物价和农业政策等方面的风险。目前发展区域可持续农业需要解决的关键问题是优化农林牧副渔结构、扩大土地经营规模、增加种粮比较效益、促进信贷资金使用、提高劳力素质。     

多环芳烃污染土壤的微生物与植物联合修复研究进展

本文综述了多环芳烃(PAHs)污染土壤中微生物降解途径、机理及生物反应器的应用,并从植物修复角度,进一步阐述了与微生物联合作用促进污染土壤中PAHs降解的途径、机理及其应用。提出了利用微生物共代谢降解及其与植物联合修复PAHs污染土壤环境的生物修复技术未来研究课题。     

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。     

多环芳烃长期污染土壤的微生物强化修复初步研究

本研究通过室内模拟试验,以急性毒性较强的菲(Phe)和遗传毒性较强的苯并[a]芘(B[a]P)为代表性多环芳烃(PAHs)污染物,以不同C源、通气状况和水分条件为调控因子,对PAHs长期污染土壤的土著微生物强化修复进行初步研究。结果表明,搅动处理使污染土壤中Phe和B[a]P的降解率分别达59.44%和26.14%,而淹水处理使两者降解率分别达46.48%和13.27%。添加C源(淀粉和葡萄糖)处理提高了土壤中PAHs的降解率,且随着C源的施用量而增加。同时也发现污染土壤中PAHs降解菌和微生物总量呈正相关,并随着PAHs降解菌数量的增加,土壤中PAHs降解率也随之提高。可见,土壤中PAHs降解速率主要决定于PAHs的降解菌数量。     

土壤多环芳烃、重金属及其复合污染的植物修复研究进展

复合污染研究已成为环境科学发展的重要方向之一,重金属和多环芳烃是土壤环境中的重要污染物,开展两者复合污染研究,对于农业环境生态安全具有重要意义。本文结合前人的研究结果,通过分析多环芳烃污染土壤的植物修复和重金属污染土壤的植物修复的研究现状,来探讨植物对重金属和多环芳烃复合污染的修复研究进展,并从生态地理学的角度提出相应的研究趋势,提出植物修复需因地制宜的特性。     

Effect of soil bacteria on the ability of polycyclic aromatic hydrocarbons (PAHs) removal by Trametes versicolor and Irpex lacteus from contaminated soil

The effect of bacteria represented by indigenous soil microflora or a mixture of soil bacteria Pseudomonas aeruginosa and Rhodococcus erythropolis on fungal growth, extracellular enzyme production and polycyclic aromatic hydrocarbons (PAHs) biodegradation efficiency in soil of white-rot fungi Trametes versicolor and Irpex lacteus was investigated. Both fungi were able to colonize soil. The growth yields measured by ergosterol were about two-fold in I. lacteus after 10 weeks. Laccase was produced in T. versicolor cultures in the presence or absence of bacteria but live bacteria reduced the laccase levels in soil about 5 times. Manganese-dependent peroxidase (MnP) was not detected in T. versicolor cultures. The amounts of MnP and laccase in I. lacteus cultures were not affected by the presence of bacteria. T. versicolor was more efficient in PAH removal for all PAHs tested although its capacity to colonize soil was lower. The removal rates of PAHs by T. versicolor in sterile soil were 1.5-fold, 5.8-fold and 1.8-fold for 2-3-ring, 4-ring and 5-6-ring PAHs, compared to I. lacteus, respectively. I. lacteus showed a low efficiency of removal of pyrene, benzo[a]anthracene and benzo[k]fluoranthene, compared to T. versicolor, whereas chrysene and benzo[b]fluoranthene were degraded by neither fungus. The main effect of the presence of the indigenous microflora or R. erythropolis and P. aeruginosa was a significant decrease of degradation of total PAHs by both T. versicolor and I. lacteus. Weak fungal/bacterial synergistic effects were observed in the case of removal of acenapthylene, benzo[a]pyrene, dibenzo[a,h]anthracene and benzo[g,h,i]perylene by I. lacteus and acenapthylene by T. versicolor. However, the bacterial effects were different in the two fungi. PAH abiotic losses represented 15 and 21% of the total PAHs after 5 and 10 weeks, respectively; naphthalene and acenaphthene were removed from the soil due to volatilization.     

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.     

In situ gradient distribution of polycyclic aromatic hydrocarbons (PAHs) in contaminated rhizosphere soil: a field study

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.     

Optimization of a solid-phase extraction method using centrifugation for the determination of 16 polycyclic aromatic hydrocarbons in water

A fast and reliable method for the determination of polycyclic aromatic hydrocarbons (PAHs) in water samples by solid-phase extraction (SPE) using centrifugation has been developed and optimized. A silica-based C18 cartridge was used; parameters affecting the extraction procedure such as type and volume of the elution solvent, breakthrough volume of the percolated water sample, drying of the sorbent, and evaporation of the elute have been studied. The innovation of this work was the examination of the use of a centrifugation technique in both the drying and elution steps. When combined with centrifugation, the volume of the elution solvent was reduced to 1 mL and the time for sorbent drying decreased also to 10 min under vacuum. Under optimal conditions, recoveries for the 16 U.S. EPA PAHs were between 70 and 85% and the relative standard deviation varied between 1 and 14%. Surrogate standard recoveries were similarly between 61 and 94% with a relative standard deviation between 2 and 15%. The simplicity of the described method, use of less of organic solvent, short procedure time, and good recoveries demonstrate the advantages of this environmentally friendly approach for routine analysis of numerous samples.     

土壤持水量对生菜生长和镉浓度的影响

通过不同水分含量处理的盆栽试验和培养试验,探索土壤持水量对生菜生物量与Cd浓度,土壤pH和土壤Cd有效态的影响。结果表明,土壤持水量显著影响生菜的生物量,75%田间持水量（water holding capacity,WHC）处理生菜地上部鲜重最高,生菜鲜重与土壤持水量呈倒V型关系。土壤持水量也显著影响生菜地上部及根中Cd浓度,2者均与土壤持水量呈显著负相关关系,土壤持水量从45%WHC增加到65%WHC,地上部Cd浓度降低41%,生菜Cd含量从超过无公害标准到低于标准。盆栽试验中,乙酸铵-Cd浓度与水分处理水平没有显著相关性,生菜地上部Cd浓度与土壤的乙酸铵-Cd态也没有显著相关性。水分对土壤pH没有显著影响,但培养试验中土壤乙酸铵-Cd与水分处理水平显著负相关。初步推测土壤水分影响生菜地上部Cd浓度,不是通过影响土壤pH和Cd有效态来实现的。因此,可以通过调节土壤水分来控制中轻度重金属污染的设施菜地上叶菜可食部分的Cd浓度,这是一种具有较好应用前景的绿色调控措施。     

不同植物篱在减少雷竹林氮磷渗漏流失中的作用

为了解不同植物篱对雷竹林氮磷渗漏流失拦截的效果,在集约经营雷竹林下坡设置黑麦草(草篱)、红叶石楠+金森女贞(灌木篱)和半野生状态粗放经营雷竹林(雷竹篱)3种植物篱,于2010年6月至10月采样并分析其渗漏水。结果表明,3种植物篱对集约经营雷竹林氮磷渗漏流失拦截效果明显,拦截前后氮磷浓度差异达极显著水平,但不同植物篱的拦截效果差异并不显著。对氮的拦截量表现为雷竹篱(81.3 kg hm-2),草篱(81.1 kg hm-2),灌木篱(77.0 kg hm-2),拦截率分别为61.0%,60.8%和57.7%;对磷的拦截量表现为雷竹篱(4.9 kg hm-2),草篱(4.7 kg hm-2),灌木篱(4.3 kg hm-2),拦截率分别是49.0%、46.9%、43.1%。半野生态粗放经营雷竹作为植物篱,既可减少氮磷面源污染,又可节省种植时间和费用,同时收获笋材,具有较大的推广价值。     

Co-occurrence of per- and polyfluoroalkyl substances, heavy metals and polycyclic aromatic hydrocarbons and their composite impacts on microbial consortium in soil: A field study

This is the first study to report the co-occurrence of per- and polyfluoroalkyl substances (PFASs), heavy metals, and polycyclic aromatic hydrocarbons (PAHs) and their impacts on the native microbial consortium in soil due to the long-term exposure. The PFASs, heavy metals, and PAHs were detected in soil samples collected at 2–6 m below the ground surface at different sampling locations in a steel-making factory. The total concentrations of PFASs varied from 6.55 to 19.79 ng g^-1, with perfluorooctane sulfonate (PFOS), perfluorobutane sulfonate, and 6:2 chlorinated polyfluorinated ether sulfonate (alternative of PFOS) being the predominant PFASs. The concentrations of arsenic, cadmium, and lead were detected in the ranges of 4.40–1 270.00, 0.01–8.67, and 18.00–647.00 mg kg^-1, respectively, and the concentration of total PAHs was detected in the range of 1.02–131.60 mg kg^-1. The long-term exposure to mixed contaminants of PFASs, heavy metals, and PAHs led to lower richness and diversity of microbial communities in soil. The soil bacterial communities were mainly composed of Pseudomonas, norank_p_GAL15, Leptothrix, norank_o_Rokubacteriales, and Acinetobacter. Correlations between soil environmental factors and microbial communities indicated that cation exchange capacity and total phosphorus were two key factors in shaping the composition of native microbial communities. Furthermore, Arthrobacter, Leptothrix, and Sphingobium were found to be significantly positively correlated with PFAS concentrations, indicating that these genera could tolerate the stress exerted by PFASs, along with the stress imposed due to the presence of heavy metals or/and PAHs.     

碱茅根际土壤盐分动态变化研究

A glasshouse experiment using a rhizobox technique was conducted to examine salt dynamics in the rhizosphere of a salt-tolerant grass, Puccinellia ciliata Bor. ‘Irwin Hunter', grown in a loamy soil, and to study the effect of rainfall flush on salt accumulation in the rhizosphere. The rhizobox (10 × 5.5 × 50 cm) had a nylon mesh (1 μm) positioned vertically in the middle to create two compartments filled with soil amended with 1 g NaCl kg^-1. The plants were grown in one compartment only. Flushed treatments received 275 mL of deionized water two days before harvest. In the plant-growing compartment, soils were sectioned vertically at 5 cm intervals. Significant differences in soil electrical conductivity (EC) (P < 0.05) and pH (P < 0.05) were observed for depths, but not between flushed and non-flushed treatments. In the no-plant compartment (rhizosphere), soil cores were taken horizontally at depths of 5, 20 and 40 cm and sliced at 1, 2, 3, 4, 5, 7, 10, 15 and 20 mm away from the roots. Soil EC and Cl^- concentration at the 5 and 20 cm depths, and Na⁺ concentration at the 5 cm depth significantly decreased (P < 0.05) with the distance away from the root, but no significant differences were observed in soil pH and concentrations of the K⁺ and Ca²⁺. The flush treatment only had significant influence on soil EC, pH, and Cl^- concentration at the 20 cm depth. Thus, salt accumulation could occur in the rhizosphere of salt-tolerant species on saline soils, and the periodic low rainfall might not have a strong influence on salt distribution in the rhizosphere and/or root zone.     

Impacts of particulate organic carbon and dissolved organic carbon on removal of polycyclic aromatic hydrocarbons, organochlorine pesticides, and nonylphenols in a wetland

Background, aim, and scope  The potential of wetlands for controlling point- and nonpoint-source pollution in surface water has attracted increasing interest. The partitioning process of organic contaminants between water, particulate organic carbon (POC) and dissolved organic carbon (DOC), impacts their behaviors in the aquatic environments. Meantime, the partitioning process of organic contaminants is closely related to their physicochemical properties, such as hydrophobicity (or K _ow), and their fates in wetlands may vary greatly depending on physicochemical properties. The aim of this study was to examine fates and removals of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and nonylphenols (NPs) in a wetland in Beijing, China, and provide useful information for ecological remediation. Materials and methods  Water samples, collected at five sites from inlet to outlet of the wetland once a month in summer 2006, were immediately filtered within 2 days through 0.45-μm glass fiber prefilters and enriched by solid-phase extraction. The filtered particulates were collected as the total suspended particulates (TSPs), freeze-dried, and Soxhlet-extracted. After extraction, samples were purified following a clean-up procedure and analyzed by GC-MS. Results  TSPs could be removed efficiently with a removal rate of 97.4%, and DOC could be moderately removed with a removal rate of 44.7% from inlet to outlet. The total removals of target contaminants varied widely from null to 82.0%. A good correlation between logK _ow and logK _oc (organic-carbon-normalized suspended-particulate partition coefficient) was observed (r ² = 0.84 for PAHs and r ² = 0.86 for OCPs, p < 0.01). Ratios of the POC-bound fraction of target contaminants (or DOC-bound fraction) to the freely dissolved fraction increased with their K _ow values. The removal of the POC fraction contributed more than 50% to the total removal for the contaminants with logK _ow > 5.0. Only a small portion of the removal was attributed to the removal of the freely dissolved fraction. Discussion  Hydrophobic compounds such as PAHs and OCPs with higher K _ow values would show stronger POC or DOC preference. Their removal depended greatly on their K _ow values and the removal of total suspended particulates. On the other hand, concentrations of NPs decreased little in the wetland, probably due to their production through degradation of their precursors and relatively low hydrophobicity. Conclusions  POC and DOC play essential roles on the fates and removals of hydrophobic organic contaminants in the wetland. The removal of target contaminants with a high K _ow should be mainly through association with the suspended particulates which were precipitated and retained in the wetland. The fates of the organic contaminants in the wetland greatly depended on their hydrophobicities. Recommendations and perspectives  Further work should be done to study the influence of hydraulic retention time and some other environmental factors, e.g., temperature, on removals and fates of organic contaminants. Behavior of NPs and their precursors in the wetland should also be investigated more thoroughly.