生物矿化在重金属污染治理领域的研究进展

生物矿化通过生物代谢影响金属及类金属物质的形态分布,进而改变金属及类金属物质的生物有效性及毒性,在环境污染治理领域成为研究热点.文献计量学结果显示,2007—2017年生物矿化研究以微生物为主要对象,在纳米颗粒物和矿区修复等方面形成热点,并在环境学、生物学、化学和工程学等领域形成交叉学科.结合典型矿化菌与重金属间的矿化关联规律和微界面反应对微生物矿化中重金属的钝化机制进行归纳:①依据矿化菌与矿化产物的关联性对矿化菌进行分类,从碳酸盐、铁锰氧化物、硫化物和磷酸盐4类矿化产物角度汇总了碳酸盐矿化菌、铁锰氧化菌、硫酸盐还原菌及磷酸盐溶解菌的代表微生物;②矿化菌通过诱导矿化的方式固定重金属离子,其中碳酸盐矿化菌、硫酸盐还原菌及磷酸盐溶解菌可以直接促进金属矿物的形成,铁锰氧化菌生成的矿物间接吸附金属离子;③微生物矿化是由外及内的过程,细胞壁及胞外多聚物具有丰富基团,在矿化初期提供吸附和成核位点,原生质体也可以提供矿化场所,在矿化中后期继续固定游离离子.但是,由于微生物复杂的细胞结构及独特的生理习性,矿化过程的微界面反应机制研究尚显不足,需要利用生物学、矿物学、环境科学等领域的先进技术进一步的探索;同时也应开展宏观生态水平的生物矿化研究,并结合实际问题完善生物矿化在环境污染治理中的理论,为重金属污染地区的治理提供新的思路和技术.      

Biodegradation of endosulfan-contaminated soil in a pilot-scale reactor-bioaugmented with mixed bacterial culture

A novel mixed bacterial culture was enriched from an endosulfan (6, 7, 8, 9, 10, 10 – hexachloro-1, 5, 5a, 6, 9, 9a-hexahydro-6, 9-methano-2, 3, 4-benzo (e) dioxathiepin-3-oxide) processing industrial surface soil. The cultures were successful in the degradation of aqueous phase endosulfan in both aerobic and anaerobic conditions. Using the cultures, endosulfan degradation in silty gravel with sand (GM) was examined via pilot scale reactor at an endosulfan concentration of 0.78 ± 0.01 mg g^{? 1} of soil, and optimized moisture content of 40 ± 1%. During operation, vertical spatial variability in endosulfan degradation was observed within the reactor. At the end of 56 days, maximum endosulfan degradation efficiency of 78 ± 0.2% and 86.91 ± 0.2% was observed in the top and bottom portion of the reactor, respectively. Both aerobic and anaerobic conditions were observed within the reactor. However, endosulfan degradation was predominant in anaerobic condition and the total protein concentration in the reactor was declined progressively down the soil depth. Throughout the study, no known intermediate metabolites of endosulfan reported by previous researchers were observed.     

铜绿假单胞菌GF31降解土壤中氯氰菊酯的性能研究

利用实验室分离获得铜绿假单胞菌GF31(Pseudomonas aeruginosa GF31,简称菌株GF31),采用气相色谱/质谱联用(GC/MS)分析技术,开展菌株GF31在实际土壤环境中对氯氰菊酯的降解特性和降解产物研究,并进行了模拟田间实验.结果表明,在土壤中菌株GF31降解氯氰菊酯的主要产物为二氯菊酸和间苯...     

On the potential of biological treatment for arsenic contaminated soils and groundwater

Bioremediation of arsenic contaminated soils and groundwater shows a great potential for future development due to its environmental compatibility and possible cost-effectiveness. It relies on microbial activity to remove, mobilize, and contain arsenic through sorption, biomethylation–demethylation, complexation, coprecipitation, and oxidation–reduction processes. This paper gives an evaluation on the feasibility of using biological methods for the remediation of arsenic contaminated soils and groundwater. Ex-situ bioleaching can effectively remove bulk arsenic from contaminated soils. Biostimulation such as addition of carbon sources and mineral nutrients can be applied to promote the leaching rate. Biosorption can be used either ex-situ or in-situ to remove arsenic from groundwater by sorption to biomass and/or coprecipitation with biogenic solids or sulfides. Introduction of proper biosorbents or microorganisms to produce active biosorbents in-situ is the key to the success of this method. Phytoremediation depends on arsenic-hyperaccumulating plants to remove arsenic from soils and shallow groundwater by translocating it into plant tissues. Engineering genetic strategies can be employed to increase the arsenic-hyperaccumulating capacity of the plants. Biovolatilization may be developed potentially as an ex-situ treatment technology. Further efforts are needed to focus on increasing the volatilization rate and the post-treatment of volatilization products.     

2种填料作为生物膜载体修复微污染河水的比较

采用序批式生物反应器(SBBR),在水温为(19.0±1.5)℃,DO≥4.5 mg/L条件下,比较基于2种生物膜填料(竹丝和空心塑料球)上的微生物对微污染河水中高锰酸钾指数(COD Mn)、总氮(TN)和总磷(TP)等的去除效果。结果表明,经过4 h的运行,竹丝作为生物膜载体时,COD Mn、TN的去除分别为17.5%~48.8%和49.38%~70.93%,但TP的去除效果不明显;而基于空心塑料球的生物膜对COD Mn的去除率仅为2.4%~42%,对TN和TP去除效果均不明显。通过显微分析发现,基于竹丝填料生物载体上微生物种类、数量明显多于空心塑料球。     

Depolymerization of polyaromatic hydrocarbons by Penicillium spp. inhabit the phyllosphere of urban ornamental plants

A variety of anthropogenic sources release hazardous polyaromatic hydrocarbons (PAHs) into the phyllosphere which is an excellent niche for diverse fungi, and some of them have PAHs degradation capabilities. Therefore, this research attempted to determine the PAHs (phenanthrene, anthracene, naphthalene, and pyrene) degradation capability of phyllosphere inhabited Penicillium species. The leaf samples were collected from highly polluted urban areas (Panchikawatta, Pettah, Orugodawatta, Maradana, Sapugaskanda, and Colombo Fort) in Sri Lanka to isolate fungal species inhabiting the phyllosphere. Furthermore, their distribution patterns among the leaf tissue layers were studied using bright-field microscopic observations. Moreover, the best PAH degraders were screened out using plate assays and confirmed through High Performance Liquid Chromatography (HPLC) analysis. Further, their enzymatic activities during the PAHs degradation were analyzed. As per the microscopic observations, the highest fungal distribution was in the upper epidermis of the leaves followed by the fungal distribution in the interspaces of palisade mesophyll layers. Out of isolated fungal species, two Penicillium spp. (Penicillium citrinum P₂₃B-91 and Penicillium griseofulvum P₉B - 30) showed the highest PAHs (phenanthrene, anthracene, naphthalene, and pyrene) degradation capabilities. Manganese peroxidase (MnP) enzyme dominated phenanthrene degradation in P. griseofulvum P₉B - 30, which showed the highest phenanthrene degradation ability (61%). In addition, P. citrinum P23B-91 was good at degrading anthracene (88%) and also displayed a higher MnP activity during the anthracene degradation than laccase and lignin peroxidase activities. The discoveries from the toxicity assay during the PAHs degradation processes revealed that the produced byproducts had no toxic effects on the fungal growth cycle and the phyllosphere. Therefore this phyllosphere Penicillium spp. are ideal for the bioremediation of polluted air in urbanized areas.     

对啶虫脒污染土壤的生物修复作用简

啶虫脒属于一种新型的氯化烟碱类杀虫剂，被认为是替代有机磷农药的重要品种之一，在世界范围内已经得到了广泛的应用，其在环境中的残留备受关注，利用微生物修复异源污染物是一种有效的措施。在实验室条件下，研究了高效降解菌D-2（噬染料菌属，Pigmentiphaga sp.）对被啶虫脒污染土壤的修复作用及其影响因素。结果表明，降解菌株在未灭菌土壤中的降解效果要略好于灭菌土壤，在土壤外源添加降解菌2×10⁸ cfu/g，温度20~40℃，弱碱性（pH 7.5）的条件下，该菌株能有效降解土壤中1~200 mg/kg的啶虫脒。啶虫脒施用对土壤种群结构有一定的影响，可以刺激细菌和真菌的生长，从而使土壤微生物群落结构发生改变，而降解菌的施用可缓解啶虫脒对土壤微生物的影响，修复受污染土壤。因此，人工接种降解菌D-2可提高土壤中啶虫脒的降解率，有效降低其在土壤中的残留。     

石油污染土壤修复技术研究进展

综述了石油污染土壤修复技术的最新发展现状,包括物化修复技术与生物修复技术,并对各项修复技术的适用性进行了综合评价。     

Enhancing plant-microbe associated bioremediation of phenanthrene and pyrene contaminated soil by SDBS-Tween 80 mixed surfactants

The use of surfactants to enhance plant-microbe associated dissipation in soils contaminated with polycyclic aromatic hydrocarbons(PAHs) is a promising bioremediation technology. This comparative study was conducted on the effects of plant-microbe treatment on the removal of phenanthrene and pyrene from contaminated soil, in the presence of low concentration single anionic, nonionic and anionic-nonionic mixed surfactants. Sodium dodecyl benzene sulfonate(SDBS) and Tween 80 were chosen as representative anionic and nonionic surfactants, respectively. We found that mixed surfactants with concentrations less than 150 mg/kg were more effective in promoting plant-microbe associated bioremediation than the same amount of single surfactants. Only about(m/m) of mixed surfactants was needed to remove the same amount of phenanthrene and pyrene from either the planted or unplanted soils, when compared to Tween 80. Mixed surfactants( 150 mg/kg) better enhanced the degradation efficiency of phenanthrene and pyrene via microbe or plant-microbe routes in the soils. In the concentration range of 60–150 mg/kg, both ryegrass roots and shoots could accumulate 2–3 times the phenanthrene and pyrene with mixed surfactants than with Tween 80. These results may be explained by the lower sorption loss and reduced interfacial tension of mixed surfactants relative to Tween 80, which enhanced the bioavailability of PAHs in soil and the microbial degradation efficiency. The higher remediation efficiency of low dosage SDBS-Tween 80 mixed surfactants thus advanced the technology of surfactant-enhanced plant-microbe associated bioremediation.     

Multi tracer test for the implementation of enhanced in-situ bioremediation at a BTEX-contaminated megasite

At the Centre for Environmental Research Leipzig-Halle (UFZ) research site in Zeitz, Germany, benzene contaminates the lower of two aquifers with concentrations of up to 20 mg/l. Since the benzene plume has a minimum length of approximately 1 km, enhanced natural attenuation measures are being considered as a remediation strategy. This study describes the performance and evaluation of a multi-species reactive tracer test using the tracers fluorescein and bromide as conservative tracers and toluene as reactive tracer. Sampling was performed over a period of six months using a detailed network of multilevel sampling wells. Toluene was only slightly retarded in comparison to bromide, whereas fluorescein was retarded considerably stronger. Therefore, it was not possible to use fluorescein as an in situ tracer for the determination of groundwater velocities. The ionic nature of fluorescein is assumed to be the major reason for its retardation. The results show that the infiltration conditions were suitable to produce a wide spreading of the tracer front along the full thickness of the aquifer. Thus, a large aquifer volume can be treated in future enhanced bioremediation measures. The total quantity of infiltrated toluene (24 l) was degraded under sulfate-reducing conditions over a flow path of 50 m. Benzylsuccinate was identified as a metabolite of toluene degradation under sulfate-reducing conditions at this site. The modelling results show that toluene degradation was described more accurately using Monod kinetics than first-order kinetics. Since toluene was only slightly retarded in comparison to bromide, sorption and desorption processes were considered to be negligible.