龙葵-镉抗性菌株修复镉污染土壤

为研究镉抗性菌株对龙葵修复镉污染土壤的效应,开展龙葵室外盆栽试验。从镉污染土壤、龙葵根际土壤和标准菌株中共筛选出3株抗镉产铁载体菌株,经16S rRNA基因序列对比分析,以上3株菌株分别被鉴定为贝莱斯芽孢杆菌(Bacillus velezensis)、苍黄假棍状杆菌(Pseudoclavibacter helvolus)和荧光假单胞菌(Pseudomonas aeruginosa)。试验中,研究了此3株菌株单种及其复合接菌处理对龙葵生长和富集镉能力以及土壤修复效率的强化作用。结果表明,与空白对照相比,复合接种苍黄假棍状杆菌和荧光假单胞菌显著(P<0.05)提高龙葵地上部分干质量(提高31.07%)、地下部分干质量(提升75.59%)、龙葵镉总积累量(提高30.28%)、地上部分镉积累量(提高31.53%)、转运系数(提高39.47%)和土壤修复效率(提高67.83%)。此外,接种以上复合菌株后土壤镉去除量的86.16%随淋溶流失,13.84%由龙葵吸收。     

产铁载体菌对龙葵修复土壤Cd污染的促进效应

通过CAS筛选培养基从龙葵根系土中筛选出2株产铁载体菌T1、Y2,经生理生化鉴定和16S r DNA序列分析,初步确定T1、Y2分别为铜绿假单胞菌和阴沟肠杆菌。将2株细菌接种至溶镉溶磷培养基中进行实验室培养,并对溶镉、溶磷结果和2株菌的胞外分泌物进行分析。结果表明,接种T1、Y2菌培养基中的有效镉、有效磷与不接菌对照相比显著增加(P0.05),2株菌分泌的草酸、丁二酸、甘油酸等有机酸使培养基pH显著降低(P0.05),促进了碳酸镉和磷酸钙的活化。在受Cd污染的灌溉土中进行龙葵盆栽实验,以灌根的方式分别接种T1、Y2菌,并对龙葵的生物量、龙葵根系土水溶态Cd浓度、龙葵吸收Cd总量及其根系土壤Cd形态的转化进行分析。结果表明:接种T1、Y2菌处理的龙葵根系土溶液Cd浓度比不接菌对照增加4.5、3.6倍,接种T1菌处理的地上部分与地下部分的干重比不接菌对照增加1.55、2.45倍,接种Y2菌处理的地上部分与地下部分的干重比不接菌对照增加1.47、2.28倍,接种T1、Y2菌处理的龙葵地上部分Cd总吸收量比不接菌对照增加1.56、1.69倍;接种T1、Y2菌处理的龙葵富集系数与未接菌对照相比增加,并没有达到显著性差异(P0.05),接种T1、Y2菌处理的转运系数与未接菌对照相比未显著性变化(P0.05)。接种菌处理有效促进了龙葵根系土壤难溶性形态Cd向可交换态Cd的转化。同时,研究发现接种T1、Y2菌可显著促进(P0.05)龙葵对土壤Cd的吸收,强化了龙葵修复土壤镉污染的能力。     

耐铅微生物的筛选及其吸附能力的初步研究

通过向土壤中添加一定量的铅来驯化土壤微生物，然后利用一系列不同铅浓度的PDA培养基分离耐铅微生物，结果获得一株耐300mg／L铅的细菌Pb—R-1和二株分别耐750mtg／L和900mg／L铅的真菌Pb—R-2和Pb—R-3，通过鉴定得知，Pb—R-2菌株为曲霉，Pb—R-3菌株为青霉；不同成分培养基（有铅或无铅）传代培养实验表明，3个菌株有稳定的耐铅遗传性；通过液体悬浮培养获得：Pb—R-1、Pb—R-2和Pb—R-3对Pb^2＋的吸附率依次为35．5％、75．5％和48．2％。采用3个菌株浸种试验表明，小麦的发芽率几乎不受影响，其它的受影响差别较大。因此，用Pb—R-2吸附小麦土壤中的铅，具有潜在的应用价值。     

蒽降解菌T2的最佳培养条件及其对蒽的生物降解动力学研究

从长期被石油污染的土壤中筛选得到一株以蒽为惟一碳源的混合菌T2，在接种量为1％，pH为7，温度为30℃，摇床转速为120r／min，蒽的初始浓度为100mg／L的条件下培养5d后，其对蒽的降解率可以达到56．6％。通过单因素实验和正交实验对菌种T2的培养条件进行研究，得到菌种T2的最佳培养条件为：接种量为5％，pH为6，温度为35℃，蒽的初始浓度为40mg／L时，最适合菌种生长。另外，菌种T2对蒽的降解动力学实验的结果表明，蒽的残留浓度Y（mg／L）与时间t（h）符合方程y=2．544e（-0.00275）t.     

不适宜生长条件对混茵降解苯胺的影响

分别从台州和衢州某化工厂的好氧池中分离筛选得到2株苯胺降解菌TZl和JH1，经16SrDNA测序鉴定为Comamonassp．TZ1和Pseudomonassp．JH1，均具有较强的苯胺降解能力，培养24h后，可使初始浓度为800mg／L的苯胺去除率达到96．4％～98．4％。在此基础上，按体积比l：1将2株菌液进行混合构建了混合菌体系，进而对比考察了苯胺初始浓度、pH、盐度和重金属等环境因子对单一菌和混合菌生长量及降解苯胺效果的影响，重点探讨混合菌对不适宜生长环境的适应性及其对苯胺的降解特性。通过单一菌和混合菌对比实验发现，在适宜苯胺初始浓度、pH和盐度条件下，混合菌的生长量略高于单一菌；在不适宜生长的高浓度苯胺、pH和盐度条件下，混合菌也表现出了更强的适应性和苯胺矿化能力。Zn2＋和Cr6＋耐受实验则表明，对于Cr6＋混合菌表现出了更强的耐受能力，而对于zn2＋并没有表现出更强的耐受能力。     

中试螺旋式自循环厌氧反应器处理安乃近制药废水的稳定性能

以制药废水实验了50m3螺旋式厌氧反应器（SPAC反应器）的稳定性。采用AugmentedDickey—Fuller（ADF）单位根检验表明，螺旋式反应器具有良好的启动和运行稳定性。负荷冲击实验显示，SPAC反应器具有较好的耐浓度冲击能力和耐水力冲击能力，所能耐受的最大浓度冲击强度大于60000（mg·h）／L（进水浓度提升2倍），所能耐受的最大水力冲击强度为300（m3·h）／d（进水流量提升50％）。SPAC反应器还具备受扰恢复能力。在反应液pH低于5．74，出水浓度、COD去除率和容积COD去除速率（VRR）分别为3500mg／L、22．30％和2．52kg／（m3·d）的工况下，经过30d恢复，出水浓度、COD去除率和VRR的恢复程度达到80％～90％。     

微生物絮凝剂有效真菌的筛选

通过真菌培养基（马铃薯培养基），对旱田土壤和活性污泥中的微生物进行筛选分离，得到3株絮凝率超过67％的菌株，其中絮凝率超过75％的高絮凝活性菌株1株——MZ52。将MZ52在产絮凝剂的培养基中进行发酵培养后，对1000mg／L高岭土悬浮液絮凝，得出MZ52菌产絮凝剂最佳培养条件，分别为摇床转速160r／min，培养时间90h，初始pH值为8．0，培养温度为40℃。     

改良型A2／O-MBR工艺的反硝化除磷性能研究

重点考察了-种改良型膜生物反应器（A2／O—MBR）的脱氮除磷性能。该工艺主要特点在于对膜池硝化回流液进行了固液分离，并将上清液和浓缩污泥分别回流至缺氧池和厌氧池，这种改进提高了系统对氮、磷的同步去除效率。实验结果表明，在水力停留时间（HRT）为12h，污泥龄（SRT）为30d，混合液回流比为200％的运行条件下，进水COD、NH4＋-N、TN和TP平均浓度分别为（225±38）、（24．8±3．9）、（26．7±2．9）和（2．90±0．53）mg／L时，增加膜池硝化回流液固液分离装置前后，系统对COD和NH4＋-N的去除都维持在较高水平，而系统对TN和TP的去除效果显著提高，出水TN和TP平均浓度分别由（14．9±3．3）mg／L和（1．95±0．72）mg／L下降到（9．4±1．9）mg／L和（0．91±0．38）mg／L，表明增加膜池硝化回流液固液分离装置显著改善了A2／O-MBR系统的脱氮除磷效果。反硝化除磷活性实验结果进一步表明，改进后系统中反硝化除磷活性占总除磷活性的比例由51．5％上升至61．7％，说明增加膜池硝化回流液固液分离装置强化了系统的反硝化除磷性能。     

NaCl盐度波动对处于污泥膨胀的耐盐脱氮污泥沉降性能的影响

以处于污泥膨胀的耐盐脱氮污泥为研究对象，分别采用有效容积为2和240L的SBR装置（编号1#和2#），在进水NH3-N浓度为40—100mg／L，pH为7．45～8．0，溶解氧为3～5mg／L，温度为28～30℃的条件下，分别研究不同NaCl盐度（0、10、20和30g／L）对污泥沉降性的影响。实验结果表明，在NaCl盐度条件下，可以明显改善耐盐脱氮污泥的沉降性。NaCl盐度越高，污泥絮凝体体积减小、丝状菌及原生动物减少趋势越明显，污泥沉降性效果越好。在30g／L盐度时，1#和2#SBR的SV30分别从95％和80％降至53％和30％，SVI分别从185．5和170．8mL／g降至127．3和78．4mL／g。     

原油生物降解影响因素的试验研究

该研究以原油为唯一碳源，从长期被石油污染土壤的浸泡液中分离、筛选出二株高效原油降解菌，即SY4和SY6，并对其影响生物降解的环境因素和营养条件进行试验研究。通过摇床实验，得出二株菌的最适生长条件为：温度30℃，pH8，摇床转速（间接反映通气量）200r／min，接种量为0．1％，最佳氮源为氯化铵（NH4Cl），最佳磷源为磷酸氢二钾和磷酸二氢钾的混合物。在一定的原油浓度范围内，SY4和SY6菌对原油具有较高的降解能力。     

EDDS and EDTA-enhanced zinc accumulation by Solanum nigrum inoculated with arbuscular mycorrhizal fungi grown in contaminated soil

The effect of two different chelating agents [EDTA and EDDS (S,S-ethylenediaminedissucinic acid)] on Zn tissue accumulation in Solanum nigrum L. grown in a naturally contaminated soil was assessed. Under those conditions, the response of the plant to the inoculation with two different isolates of arbuscular mycorrhizal fungi (AMF)--Glomus claroideum and Glomus intraradices--was also studied. Plants grown in the local contaminated soil (Zn levels of 433mg kg(-1)) accumulated up to 1191mg kg(-1) of Zn in the roots, 3747mg kg(-1) in the stems and 3409mg kg(-1) in the leaves. S. nigrum plants grown in the same soil spiked with extra Zn (Zn levels of 964mg kg(-1)) accumulated up to 4735, 8267 and 7948mg Zn kg(-1) in the leaves, stems and roots, respectively. The addition of EDTA promoted an increase in the concentration of Zn accumulated by S. nigrum of up to 231% in the leaves, 93% in the stems and 81% in the roots, while EDDS application enhanced the accumulation in leaves, stems and roots up to 140, 124 and 104%, respectively. In the stems, the presence of Zn was predominantly detected in the cortex collenchyma cells, the starch sheath and the internal phloem and xylem parenchyma, and the addition of chelating agents did not seem to have an effect on the localisation of accumulation sites. The devise of a chelate-enhanced phytoextraction strategy, using chelating agents and AMF, is discussed.     

Behaviour of alpha-, beta-, gamma-, and delta-hexachlorocyclohexane in the soil-plant system of a contaminated site

The behaviour of the organochlorine pesticide hexachlorocyclohexane (HCH) is investigated. The concentrations of alpha-, beta-, gamma-, and delta-HCH isomers were measured in soils, rhizosphere and vegetation in a contaminated area in Galicia (NW Spain). The total concentration of HCH in soils reached values close to 20,000 mgkg(-1). The plants analysed (Avena sativa L., Chenopodium spp., Solanum nigrum L., Cytisus striatus (Hill) Roth, and Vicia sativa L.) accumulated HCH, especially the beta-HCH isomer, in their tissues. The most likely mechanisms of HCH accumulation in plants were sorption of soil HCH on roots and sorption of volatilized HCH on aerial plant tissues. The concentrations of HCH obtained from the bulk and rhizosphere soils of selected plant species suggest that roots tend to reduce levels of the HCH isomers in the rhizosphere. The results reflect the importance of vegetation in the distribution of organochlorine compounds in the soil-plant system.     

Cd、Pb复合污染下柠檬酸对龙葵修复效率及抗氧化酶的影响

植物修复土壤重金属被普遍认为是清洁、经济的生物修复方法。为了提高生物修复土壤重金属污染的效率,在室内盆栽实验中添加柠檬酸作为螯合剂促进龙葵对重金属的吸收,并研究其生理活性的变化。结果表明:当添加柠檬酸浓度为10 nmol/kg时,龙葵生物量显著提高(P<0.05),各部分生物量表现为:茎>叶>根;随着柠檬酸浓度的增加,龙葵对重金属Cd的吸收量显著(P<0.05)增加,在10 nmol时总吸收量最大,为229.85μg/g DW;龙葵对Cd、Pb的富集系数均在柠檬酸浓度为5 nmol/kg时达到最大;Pb吸收量随柠檬酸浓度增加表现出先增大后减小的趋势;添加柠檬酸促进了龙葵对Cd的吸收,增强了抗氧化酶活性,而对Pb的吸收效果不明显。     

Application of manure and compost to contaminated soils and its effect on zinc accumulation by Solanum nigrum inoculated with arbuscular mycorrhizal fungi

Zn accumulation in Solanum nigrum grown in naturally contaminated soil in the presence of different types of organic amendments was assessed. Under the same conditions, the response of the plant to inoculation with two different isolates of arbuscular mycorrhizal fungi (AMF) (Glomus claroideum and Glomus intraradices) was also evaluated. S. nigrum grown in the non-amended soil always presented higher Zn accumulation in the tissues, with the addition of amendments inducing reductions of up to 80 and 40%, for manure and compost, respectively, and enhancing plant biomass yields. The establishment of S. nigrum in the Zn contaminated soil combined with the application of amendments led to a 70-80% reduction in the amount of Zn leached through the soil. The use of S. nigrum in combination with manure appeared as an effective method for reducing the effects of soil contamination, diminishing Zn transfer to other environmental compartments via percolation.     

Solanum nigrum grown in contaminated soil: effect of arbuscular mycorrhizal fungi on zinc accumulation and histolocalisation

Zn tissue accumulation in Solanum nigrum grown in a non-contaminated and a naturally contaminated Zn matrix and the effect of inoculation with different arbuscular mycorrhizal fungi (AMF) on metal uptake were assessed. S. nigrum grown in the contaminated soil always presented higher Zn accumulation in the tissues, accumulating up to 1622 mg Zn kg(-1). The presence of both Glomus claroideum and Glomus intraradices enhanced the uptake and accumulation of Zn by S. nigrum (up to 83 and 49% higher Zn accumulation, respectively). The main deposits of the metal were found in the intercellular spaces and in the cell walls of the root tissues, as revealed by autometallography, with the inoculation with different AMF species causing no differences in the location of Zn accumulation. These findings indicate that S. nigrum inoculated with selected heavy metal tolerant AMF presents extracting and accumulating capacities, constituting a potentially suitable remediation method for Zn polluted soils.     

Simultaneous removal of phenanthrene and cadmium from contaminated soils by saponin, a plant-derived biosurfactant

Batch experiments were conducted to evaluate the performance of saponin, a plant-derived biosurfactant, for simultaneously removing phenanthrene and cadmium from the combined contaminated soils. Results showed that phenanthrene was desorbed from the contaminated soils by saponin with the partition of phenanthrene into surfactant micelle, meanwhile cadmium was effectively removed from the contaminated soils by the complexation of cadmium with the external carboxyl groups of saponin micelle. The efficiencies of saponin for the removal of phenanthrene and cadmium from the contaminated soils were greater than that of Triton X100 and citric acid, respectively. At concentration of 3750 mg/L, saponin has a removal rate of 87.7% and 76.2% of cadmium and phenanthrene, respectively, from the combined contaminated soil. The removals of cadmium and phenanthrene from the soils were not obviously constrained each other. Thus, saponin has the potential for the removal of heavy metal and PAHs from the combined contaminated soils.     

Improvement of rape (Brassica napus) plant growth and cadmium uptake by cadmium-resistant bacteria

This study focuses on the screening of cadmium-resistance bacterial strains from heavy metal-polluted soils to examine their plant growth promotion and cadmium uptake in rape (Brassica napus). A large number of bacteria were isolated from heavy metal-polluted soil in Nanjing, China. Thirty isolates showing cadmium-resistance on Cd-amended medium were selected and evaluated for their potential to solubilize cadmium carbonate in solution culture. Atomic absorption spectrometer analysis showed variable amounts of water-soluble Cd (ranging from 24 to 117 mg l(-1)) released by the cadmium-resistant bacterial strains from cadmium carbonate. Qualitative analysis confirmed the presence of indole acetic acid as the auxin in the culture of these cadmium-resistant bacterial strains. Root elongation assay conducted on rape under gnotobiotic conditions demonstrated increases (up to 31%) in root elongation of inoculated rape seedlings compared to the control plants. Based upon cadmium-resistance, bio-activation of CdCO3 and growth-promoting activity, three isolates were selected for promoting plant growth and uptake of cadmium from cadmium-amended soil in pot experiments. Inoculation with the isolates was found to increase root dry weight (ranging from 8% to 20%) and shoot dry weight (ranging from 6% to 25%) of rape. An increase in cadmium content varying from 16 to 74%, compared to the non-inoculated control, was observed in rape plants cultivated in soil treated with 100 mgCd kg(-1) (as CdCl2) and inoculated with the isolates. The bacterial isolates were also able to colonize and develop in the rhizosphere soil of rape after root inoculation.     

Phytoextraction potential of two Rumex acetosa L. accessions collected from metalliferous and non-metalliferous sites: effect of fertilization

Metal tolerance and phytoextraction potential of two common sorrel (Rumex acetosa L.) accessions, collected from a Pb/Zn contaminated site (CS, Lanestosa) and an uncontaminated site (UCS, Larrauri), were studied in fertilized and non-fertilized pots prepared by combining soil samples from both sites in different proportions (i.e., 0%, 33%, 66% and 100% of Lanestosa contaminated soil). The original metalliferous mine soil contained 20480, 4950 and 14 mg kg(-1) of Zn, Pb and Cd, respectively. The microcosm experiment was carried out for two months under greenhouse controlled conditions. It was found that fertilization increased mean plant biomass of both accessions as well as their tolerance. However, only the CS accession survived all treatments even though its biomass decreased proportionally according to the percentage of contaminated mine soil present in the pots. This metallicolous accession would be useful for the revegetation and phytostabilization of mine soils. Due to its high concentration and bioavailability in the contaminated soil, the highest values of metal phytoextracted corresponded to Zn. The CS accession was capable of efficiently phytoextracting metal from the 100% mine soil, indeed reaching very promising phytoextraction rates in the fertilized pots (6.8 mg plant(-1) month(-1)), similar to the ones obtained with hyperaccumulator plants. It was concluded that fertilization is certainly worth being considered for phytoextraction and revegetation with native plants from metalliferous soils.     

上海市桃浦垃圾填埋场封场植被的重金属吸收和积累特征

城市垃圾填埋场的生态修复问题越来越受到重视，选择合适的封场植被对生态恢复至关重要。本研究对上海市桃浦垃圾填埋场的土壤和29种优势植物的重金属含量进行检测，结果显示，该填埋埋场土壤呈现Zn和Cd的中度复合污染。在研究的优势植物中，杨树、雪松和夹竹桃吸收Zn的能力较强，杨树、紫薇、金丝桃吸收Cd的能力较强。荆芥表现为重金属Zn的富集型植物；龙葵表现为重金属Cd的富集型植物；麦冬和狗尾巴草则表现为重金属的根部囤积型植物。可综合选择这些植物用于城市垃圾填埋场的植物修复和植被恢复。     

Effects of compost and phosphate on plant arsenic accumulation from soils near pressure-treated wood

Leaching of arsenic (As) from chromated copper arsenate (CCA)-treated wood may elevate soil arsenic levels. Thus, an environmental concern arises regarding accumulation of As in vegetables grown in these soils. In this study, a greenhouse experiment was conducted to evaluate As accumulation by vegetables from the soils adjacent to the CCA-treated utility poles and fences and examine the effects of soil amendments on plant As accumulation. Carrot (Daucus carota L.) and lettuce (Lactuca sativa L.) were grown for ten weeks in the soil with or without compost and phosphate amendments. As expected, elevated As concentrations were observed in the pole soil (43 mg kg(-1)) and in the fence soil (27 mg kg(-1)), resulting in enhanced As accumulation of 44 mg kg(-1) in carrot and 32 mg kg(-1) in lettuce. Addition of phosphate to soils increased As accumulation by 4.56-9.3 times for carrot and 2.45-10.1 for lettuce due to increased soil water-soluble As via replacement of arsenate by phosphate in soil. However, biosolid compost application significantly reduced plant As uptake by 79-86%, relative to the untreated soils. This suppression is possibly because of As adsorbed by biosolid organic mater, which reduced As phytoavailability. Fractionation analysis showed that biosolid decreased As in soil water-soluble, exchangeable, and carbonate fraction by 45%, whereas phosphate increased it up to 2.61 times, compared to the untreated soils. Our results indicate that growing vegetables in soils near CCA-treated wood may pose a risk of As exposure for humans. Compost amendment can reduce such a risk by reducing As accumulation by vegetables and can be an important strategy for remediating CCA-contaminated soils. Caution should be taken for phosphate application since it enhances As accumulation.