Hydrocarbons contamination and microbial degradation in mangrove sediments of the Niger Delta region (Nigeria)

The distribution of aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs), and their degradability by bacteria in epipelic and benthic sediments from Qua Iboe Estuary mangrove ecosystem and associated creeks were investigated. The research findings revealed that total aliphatic hydrocarbons in sediments ranged from 16.82 mg·kg ^?1 to 210 mg kg ^?1, wheras total PAHs ranged from 6.30 to 35.55 mg·kg ^?1 dry weight of sediment. Low molecular mass (i.e. the 2–3-ring) PAHs were predominant in almost all the sampling points, whereas the higher molecular masses (4-, 5- and 6-ring PAHs) had the lowest concentrations. In general, the sediment samples ES ₂ (39.7%), ES ₃ (24.8%), BS ₁ (46.7%), BS ₂ (49.9%) and BS ₃ (44.2%) showed<50% contributions of Σ combustion–derived PAH (COMP-PAH) concentration to the Σ PAH concentrations, whereas ES ₁ (57%) contained>50% of COMP-PAHs. Our results have also shown that many mangrove bacteria have strong capacity to utilise Qua Iboe Light (QL) crude oil as the sole source of carbon and energy, while lower number of bacterial species including Bacillus sp., Micrococcus sp., Pseudomonas aeruginosa, Alcaligenes sp. and Flavobacterium sp. exhibited detectable PAHs degradability; and as such may serve as efficient degraders of QL crude oil contamination of mangrove ecosystem.     

Presence of hydrocarbon-degrading bacteria in the gills of mussel Mytilus galloprovincialis in a contaminated environment: a mesoscale simulation study

A number of previous studies have shown that the relationships of symbiosis existing between mussels and microorganisms are directly dependent on the environmental conditions. However, little is known about existing relationships between mussels and bacteria in hydrocarbon-impacted marine environments. The aim of this preliminary study is to investigate the presence of oil-degrading bacteria in the mussel Mytilus galloprovincialis during growth in polluted ecosystems. All the experiments were carried out in a mesocosm system designed to simulate chronic pollution and to enable direct exposure of mussels to chemicals. Quantitative (4′,6-diamidino-2-phenylindole, colony-forming units, Most Probable Number) analyses and screening (presence/absence) of metabolic functional genes were performed to analyse bacterial populations inside the gills of mussels exposed and not exposed to hydrocarbons. The data obtained show that the presence of hydrocarbons affected the abundance of bacteria inside the gills of specimens and determines selection for specific (hydrocarbon-degrading) bacteria (i.e. Alcanivorax sp. and Marinobacter sp.). However, is not yet clear whether the presence of such genera of bacteria inside the mussel is due to symbiosis or as a result of filtration.     

影响总氮测定的关键因素研究

为了解决水质分析中总氮测定的实际问题,应用GB 11894—1989《碱性过硫酸钾氧化紫外分光光度法》,从总氮测定方法的原理出发,探讨了影响总氮测定的关键因素。结果表明:在标准分析方法的基础上,要提高水样总氮分析的准确度,可采用50 mL优质比色管进行消解,选用优级纯的过硫酸钾,消解后的冷却时间需延长至2 h。     

首钢水钢100t转炉一次烟气新OG法除尘工程

首钢水钢二炼钢厂新建100 t转炉一次烟气除尘采用新OG法,针对此工程,介绍了新OG法工艺流程,分析了系统设计中的关键技术和调试、运行管理中值得注意的问题,并给出了系统设备的主要参数,可供参考。     

硫酸盐对医药化工废水厌氧系统运行稳定性的影响

以获得硫酸盐还原能力的厌氧装置为研究对象,研究进水中不同硫酸盐浓度对厌氧反应器的运行效果的影响。试验结果表明:硫酸盐添加量为300 mg/L时,厌氧反应器出水COD浓度最低,COD去除率为76.1%,同时厌氧反应器出水中VFA的浓度最低;在硫酸盐添加量为400 mg/L时,此条件下获得产甲烷量最高,达240~260 mL/g;出水硫化氢浓度则随着硫酸盐添加量的增加而增加。在500 m3的UASB反应器内进行连续厌氧处理试验,结果表明添加硫酸盐后厌氧反应器的运行情况稳定。     

黑臭水净化菌株的筛选及其水质改善能力

生活污水的过度排放引起的水体黑臭是一个亟待解决的环境问题.为建立黑臭水的微生物净化方法,从不同重污染水体或底泥中筛选获得了多种光合细菌,分析发现其中10种光合细菌(P1～P10)及其混合菌(Pm)对黑臭指标有改善效果.黑臭水厌氧光照净化试验结果表明,菌液投加量为1.0%,3 d后光合细菌P1,P2,P3,P4,P8,P9和Pm对人工黑臭水COD_Cr,NH₃-N,S2-,色阈值及臭阈值去除率分别为75.00%～ 82.00%,24.20%～27.97%,72.03%～87.89%,58.90%～69.08%和75.29%～87.89%,其中P9的效果最好.黑臭水兼性厌氧光照净化试验结果表明,菌液投加量为1.0%,3 d后光合细菌P2,P3,P4,P8,P9和Pm对人工黑臭水中的COD_Cr,NH₃-N,S2-,色阈值及臭阈值去除率分别为60.67%～79.92%,35.92%～40.16%,72.03%～82.93%,58.25%～66.55%和75.29%～85.09%,　ρ(DO)由0.54 mg/L增至1.80～2.63 mg/L,其中P2和P9的效果最好.经鉴定P9为沼泽红假单胞菌.研究发现,在菌液投加量为0.1%,30 ℃,厌氧光照条件下P9可明显改善水的黑臭指标.      

环境激素对叔辛基酚降解菌的筛选、鉴定及降解特性

为了研究环境激素4-t-OP(对叔辛基酚)的生物降解,从扬州市汤汪生活污水处理厂二沉池污泥中筛选得到1株能以4-t-OP为唯一碳源进行生长的降解菌株,标示为TW30,16S rRNA测试其为不动杆菌属(Acinetobacter sp.),通过摇瓶试验测试其降解活性.结果表明:在40℃、初始pH为6.0、ρ(4-t-OP)为5 mg/L的无机盐培养基中,5 d后降解率可达99.03%;降解过程满足一级反应模型,降解速率常数(k)为0.875 d-1,半衰期(t1/2)为0.8 d.这说明TW30是一株高效的4-t-OP降解菌.此外,培养温度的升高和额外Ca2+、Mn2+的加入可以提高TW30降解4-t-OP的效率,而在5～25 mg/L范围内提高初始ρ(4-t-OP)以及额外加入磷酸盐、NH4+、Mg2+、Fe2+、Na+、Zn2+、Cu2+等无机盐和葡萄糖、CH3COO-等碳源则会降低降解率.      

崇明东滩夏冬季表层沉积物细菌多样性研究

以长江口崇明东滩高、中、低潮滩夏、冬两季表层沉积物中基因组DNA为模板,PCR扩增样品中细菌16S rRNA基因V3区片段,通过克隆、测序,构建相应基因文库.系统发育分析结果表明,崇明东滩高、中、低潮滩表层沉积物共包含12个主要门类的细菌:变形菌门(Proteobacteria)(α-、β-、γ-、δ-和ε-亚群)、拟杆菌门(Bacteroidetes)、放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)、绿弯菌门(Chloroflexi)、厚壁菌门(Firmicutes)、螺旋体门(Spirochaetes)、疣微菌门(Verrucomicrobia)、浮霉菌门(Planctomycetes)、绿菌门(Chlorobi)、网团菌门(Dictyoglomi)、硝化螺旋菌门(Nitrospirae),此外还存在大量未被认知的序列.中潮滩和低潮滩的优势菌为变形菌,高潮滩的优势菌为拟杆菌.DOTUR多样性分析结果表明,崇明中潮滩细菌多样性最高,低潮滩次之,高潮滩最低;夏季细菌多样性高于冬季.夏、冬两季细菌群落差异高潮滩最大,低潮滩次之,中潮滩最小.     

内蒙古高原干涸湖泊反硝化及甲烷氧化细菌的群落分析

以内蒙古高原半干旱草原区干涸湖泊为研究对象,应用末端限制性片段长度多态性(T-RFLP)技术对湿地土壤中的反硝化和甲烷氧化关联菌群的关键功能基因nosZ和pmoA进行了研究,根据末端限制性片段(T-RFs)分析了两种菌群的群落结构及多样性变化,以及环境因素所产生的影响,并探讨了土壤微生物群落对湖泊干涸的响应机制.结果表明:干涸湖泊的湖心、湖底土壤反硝化和甲烷氧化细菌多样性指数较高,群落结构较复杂;而较早干涸的湖坡以及相邻草原对照区,两个菌群多样性指数较低,群落结构相对单一.从湖心到相邻草原,反硝化和甲烷氧化细菌的群落相似度逐渐降低,显示两个菌群处于动态演替中.湖泊干涸过程中,水分含量和有机质含量对反硝化和甲烷氧化细菌的群落结构影响显著;高pH值和高铵态氮分别对反硝化和甲烷氧化细菌有抑制作用.随着湖泊干涸,土壤微生物群落因环境扰动而受到胁迫,这一过程会加剧CO2等温室气体的排放.     

近地层臭氧浓度升高对稻田土壤氨氧化与反硝化细菌活性的影响

利用中国唯一的稻麦轮作臭氧FACE（free-air O3 concentration enrichment,开放式空气臭氧浓度增高）试验平台,研究近地层臭氧浓度升高对稻田不同生育时期植株氮吸收量、土壤氮含量与脲酶活性、土壤氨氧化细菌与反硝化细菌数量以及成熟期土壤硝化与反硝化作用强度的影响。结果发现,臭氧浓度升高条件下,单株水稻（Oryza sativaL.）的氮吸收量趋于升高,土壤全氮含量趋于下降、脲酶活性趋于增强,在成熟期土壤全氮与对照相比平均下降9%,土壤脲酶活性与对照相比平均升高13%。在水稻整个生长季节,土壤氨氧化细菌和反硝化细菌的数量均呈现出先增多后减少的趋势,且均在开花期达到峰值,但臭氧熏蒸土壤与对照相比趋于升高;在水稻成熟期,土壤中单个氨氧化细菌和反硝化细菌的活性均趋于下降,土壤硝化强度和反硝化强度与对照相比也平均下降17%和24%。结果表明,近地层臭氧浓度升高条件下,稻田土壤氮素转化因为水稻氮素吸收增强而加快,土壤氨氧化细菌和反硝化细菌的数量均趋于增多,但它们的生理代谢活性均趋于下降。