Effects of sepiolite and biochar on microbial diversity in acid red soil from southern China

Sepiolite and biochar can immobilize heavy metals and organic pollutants in soil effectively, but their impact on the soil microbial community and diversity is still unclear. High-throughput Illumina MiSeq method was used to study the effects of sepiolite and biochar on the diversity of microbial communities in acid red soil amended with cadmium and atrazine. A total of 47,472 microbiological Operational Taxonomic Units (OTUs) were found in all the treated soil samples. Sepiolite and biochar enriched the diversity of soil microbes at different classification levels and OTUs, but the effect of biochar was stronger than that of sepiolite. A Venn diagram showed that compared with other treatments, adding 2% biochar could promote the growth of specific microbes, which is better than the case for 5% biochar. The heat map of species abundance cluster showed that the dominant microbes in soil were different for different treatment doses of sepiolite and biochar. Among all the soil treatments, the top ten dominant bacterial phyla (from high to low dominance) were: Actinobacteria, Proteobacteria, Firmicutes, Bacteroidetes, Acidobacteria, Gemmatimonadetes, Chloroflexi, Planctomycetes, Cyanobacteria­, and Verrucomicrobia. The addition of sepiolite and biochar promoted the restoration of the microbial community diversity in contaminated soil.     

Emission factors of gaseous carbonaceous species from residential combustion of coal and crop residue briquettes

Experiments were performed to measure the emission factors (EFs) of gaseous carbonaceous species, such as CO₂, CO, CH₄, and non-methane volatile organic compounds (NMVOCs), from the combustion of five types of coal of varying organic maturity and two types of biomass briquettes under residential burning conditions. Samples were collected in stainless steel canisters and 2,4-dinitrophenylhydrazine (DNPH) cartridges and were analyzed by GC-FID/MS and HPLC, respectively. The EFs from crop residue briquette burning were generally higher than those from coals, with the exception of CO₂. The dominant NMVOC species identified in coal smoke were carbonyls (41.7%), followed by C2 unsaturated hydrocarbons (29.1%) and aromatics (12.1%), while C2 unsaturated hydrocarbons were the dominant species (68.9%) emitted from the combustion of crop residue briquettes, followed by aromatics (14.4%). A comparison of burning normal crop residues in stoves and the open field indicated that briquettes emitted a larger proportion of ethene and acetylene. Both combustion efficiency and coal organic maturity had a significant impact on NMVOC EFs from burning coal: NMVOC emissions increased with increasing coal organic maturity but decreased as the combustion efficiency improved. Emissions from the combustion of crop residue briquettes from stoves occurred mainly during the smoldering process, with low combustion efficiency. Therefore, an improved stove design to allow higher combustion efficiency would be beneficial for reducing emissions of carbonaceous air pollutants.     

Effects of two different intercropping systems on arbuscular mycorrhizal fungal colonization and polychlorinated biphenyl (PCB) dissipation北大核心CSCD

Polychlorinated biphenyls (PCBs) are typical organic contaminants in the environment. It is indicated that plants and soil microorganisms have a positive synergistic effect on the remediation of PCB-contaminated soil. To investigate the effect of intercropping on arbuscular mycorrhizal (AM) fungal colonization and PCB remediation, a pot-cultivation experiment with two intercropping treatments, corn (Zea mays L.) / ryegrass (Lolium perenne L.) and corn/alfalfa (Medicago sativa L.), and a corn monoculture was conducted in a greenhouse. All treatments were inoculated with Funneliformis mosseae M47V. Plant biomass, root mycorrhizal colonization rate, concentration of PCBs and their homologs in soil, 16S rDNA gene abundance, and community composition measured by Terminal Restriction Fragment Length Polymorphism (T-RFLP) were determined after harvesting the plants. Intercropping significantly increased the root mycorrhizal colonization rate and plant biomass of corn (P < 0.05), as well as the available N content of the soil. A significant difference of the bacterial community composition was found among different treatments (P < 0.05). Compared with corn monoculture, corn/alfalfa intercropping significantly increased soil bacteria abundance (P < 0.05). The dissipation rates of total PCBs, as well as that of penta-chloro biphenyls were significantly increased in the intercropping treatments, when compared to the corn monoculture treatment. Moreover, corn/ryegrass intercropping has a significantly positive effect on the dissipation of tri-chloro biphenyls. Non-metric multidimensional scaling (NMDS) analysis indicated that the PCBs homologues composition were significantly correlated with the relative abundance of 128 bp and 148 bp T-RFs. Corn intercropping with ryegrass or alfalfa has a positive effect on root mycorrhizal colonization rate and plant biomass of corn. Inoculation of AM fungi in intercropping treatments significantly improved the efficiency of PCB remediation by promoting bacterial abundance and shifting the bacterial community composition. In conclusion, intercropping combined with AM fungi have positive synergistic effects on the remediation of PCB-contaminated soils. © 2018 Science Press. All rights reserved.     

Recent advances in the photocatalytic reduction of carbon dioxide

Fossil fuels are currently the major energy source and are rapidly consumed to supply the increasing energy demands of mankind. CO₂, a product of fossil fuel combustion, leads to climate change and will have a serious impact on our environment. There is an increasing need to mitigate CO₂ emissions using carbon–neutral energy sources. Therefore, research activities are devoted to CO₂ capture, storage and utilization. For instance, photocatalytic reduction of CO₂ into hydrocarbon fuels is a promising avenue to recycle carbon dioxide. Here we review the present status of the emission and utilization of CO₂. Then we review the photocatalytic conversion of CO₂ by TiO₂, modified TiO₂ and non-titanium metal oxides. Finally, the challenges and prospects for further development of CO₂ photocatalytic reduction are presented.     

衡阳市区和衡山背景站臭氧浓度变化规律的对比分析

选取衡阳市区和衡山背景站臭氧自动监测数据,分析两地的臭氧污染特征。对空气质量的优良率情况、臭氧作为首要污染物的变化情况、臭氧浓度的日变化特征、典型时段的浓度变化特征、臭氧浓度的月际变化特征和臭氧与PM_(2.5)的关联情况等进行了分析。结果表明,多云及阴雨天气时,衡阳市区的臭氧浓度日变化幅度大于衡山背景站。夏季,衡阳市区和衡山背景站的臭氧浓度的日变化特征规律差异较大,臭氧浓度分布比较分散,前者为典型的单峰形,后者则波动平缓。冬季,日变化幅度不大,但衡阳市区的臭氧浓度明显低于衡山背景站。衡山背景站和衡阳市区的臭氧基本同步变化,但日均值高于衡阳市区。     

珠穆朗玛峰北坡绒布冰川区水体的化学特征

１９９７－０５在珠峰地区绒布冰川采集的４类水样的实测资料表明,本区各类水体都呈碱性,ＰＨ值的大小顺序为：湖水〉湖水〉表层雪。河水和湖水的阴离子以ＳＯ＾２－４为最大,而表层雪样品以Ｃｌ－最大;     

中美环境行政听证程序的比较

环境进政听证是促进环境行政主管部门公正行使权力、保护环境行政管理相对人合法权利的法定程序。比较中美环境行政听政程序在沿革，体系，具体内容，适用范围等方面的特点，探讨完善中国环境行政听证的途径。     

北美自由贸易区和欧盟的环境政策：趋向,启示与对策

以北美自由贸易区和欧盟为代表的区域性经济集团已在经济利益与环境保护挂钩的制度性安排方面取得诸多进展，它们不同程度地在机构设置、协定条款、资金安排等方面强化了环境要求，并在国际环境公约的执行上表现出积极、灵活的特点。这一切都将为未来多边经济体系中环境问题的协商和解决开辟了新的途径， 也为我国在实施可持续发展过程中的环境制度化建设提供可鉴之处。     

感光胶片废水的水解酸化—好氧处理工艺试验

对感光胶片有机生产废水处理工艺进行了方法采用水解酸化－好氧串联工艺和传统活性污泥法两种方法并进行对照。结果经水解酸化处理，废水的ＢＯＤ５／ＣＯＤｃｒ可提高至０．５４－０．５６，平均增加了１７％左右，证实了水解酸化菌在该工艺条件下具有搞高效片废水可生化性的功能。     

AT－SS复合颗粒吸附剂的制备和除铅性能研究

通过颗粒吸附剂在含铅溶液中的振荡实验．研究了凹凸棒石粘土（ＡＴ）和钢渣（ＣＳ）、水泥（ＳＮ）、石英砂（ＳＳ）制得的多种复合颗粒吸附剂的除铅性能及制备条件．确定出最佳颗粒吸附剂为ＡＴ－ＳＳ，混合比为５：１，７００℃下焙烧１２０ｍｉｎ．对铅的静态吸附容量高达５００ｍｇ／ｇ以上，动态吸附容量为６０ｍｇ／ｇ．在１．５ｍｌ／ｍｉｎ的流速下，穿透时间为２０ｈ，洗脱回收率为４８．３％．当Ｐｂ进样量为２００ｍｇ／Ｌ时，ＡＴ－ＳＳ吸附剂在２３６倍床体积之内，流出液浓度低于排放标准．