Microbial Communities in Composite Biofilms Participating in the Degradation of PCB

A moorland soil site polluted with PCB showed a high diversity ofmetabolically active bacteria. Beside frequent types of 16S rRNAsequences similar to those of the species ofSphingomonasand the Acidobacterium phylum an unusual high number ofsequences from the genus Burkholderia were found. Burkholderia was also the main genus in isolates enriched onbiphenyl or various chlorobenzoates. In microcosm experimentssterilized surfaces exposed to PCB polluted soil always showed thepresence of clay aggregates formed by bacteria attached to thesubstratum. The bacteria use the PCB loaded clay colloids astransport medium for the water insoluble substrate to get accessto the carbon source. This is a novel mechanism of how bacteria dealwith hydrophobic substrates.     

水稻土团聚体Cu2+吸附过程中铝的溶出及土壤溶液pH变化

采用低能量超声波分散和冷冻机干燥法提取太湖地区水稻土(黄泥土)不同粒径团聚体颗粒,用平衡吸附法研究团聚体对重金属Cu2+吸附过程中铝的溶出及土壤溶液pH变化,以及不同pH的Cu2+溶液中铝的溶出量的变化.结果表明,团聚体对Cu2+的吸附过程,发生铝的溶出和土壤溶液pH下降,溶出量和pH下降幅度随Cu2+吸附量增加而增加,相同条件下铝溶出量和pH下降幅度大小顺序为:粗粉砂级>粉砂级>砂粒级>黏粒级,与氧化铁和有机质含量大小顺序相反.Cu2+溶液pH下降,铝的溶出量增加显著.氧化铁和有机质对Cu2+吸附过程铝的溶出和土壤溶液pH下降具有一定的抑制和缓冲作用.     

缙云山不同土地利用方式下土壤团聚体中活性有机碳分布特征

于缙云山阳坡同一海拔高度处选择了亚热带常绿阔叶林(简称林地)、荒地、坡耕地和果园4种土地利用方式,在0~60 cm的土壤深度内每隔10 cm采集一个土壤样品,测定大团聚体(2 mm)、中间团聚体(0.25~2 mm)、微团聚体(0.053~0.25 mm)以及粉+黏团聚体(0.053 mm)这4种粒径团聚体内的土壤活性有机碳(labile organic carbon,LOC)的含量,分析缙云山不同土地利用方式对团聚体LOC的影响.结果表明,各粒径团聚体中LOC含量均随土壤深度的增加而显著降低,呈现出明显的垂直递减性;在0~60 cm土壤深度的各土层上,基本上均表现为林地和撂荒地各粒径团聚体中LOC含量高于坡耕地和果园.采用土壤等质量方法计算LOC储量,显示大团聚体LOC储量为林地(3.68 Mg·hm-2)撂荒地(1.73 Mg·hm-2)果园(1.43 Mg·hm-2)坡耕地(0.54 Mg·hm-2);中间和微团聚体LOC储量为撂荒地(7.77 Mg·hm-2和5.01 Mg·hm-2)林地(4.96 Mg·hm-2和2.71 Mg·hm-2)果园(3.55 Mg·hm-2和2.10 Mg·hm-2)坡耕地(1.68 Mg·hm-2和1.35 Mg·hm-2);粉+黏团聚体LOC储量为撂荒地(4.32 Mg·hm-2)果园(4.00 Mg·hm-2)林地(3.22 Mg·hm-2)坡耕地(2.37Mg·hm-2).除粉+黏团聚体LOC储量略低于果园外,林地和撂荒地其他粒径团聚体LOC储量均高于果园和坡耕地,表明林地开垦为果园和坡耕地会导致LOC的降低,而坡耕地撂荒则会促进LOC的增加.林地和荒地LOC主要分布在中间团聚体,而果园和坡耕地则为粉+黏团聚体内LOC储量最高,表明在土地利用的转变过程中,粒径较大的团聚体更容易积累或损失LOC.4种土地方式下各粒径团聚体中LOC分配比例随土壤深度的增加而降低,果园和坡耕地各粒径团聚体内LOC分配比例略高于林地和撂荒地,表明林地和撂荒地土壤有机碳(soil organic carbon,SOC)性质更稳定,更有利于碳在土壤中的留存,从而减少SOC矿化分解向大气的释放.相关分析表明,土壤团聚体LOC含量与土壤团聚体总有机碳含量呈极显著正相关关系,表明团聚体LOC可以作为衡量西南地区山地土壤团聚体有机碳动态的一个敏感性指标.     

石漠化山地植被恢复过程土壤团聚体氮分布及与氮素矿化关系研究

为阐明岩溶石漠化区植被恢复对土壤氮素积累与供应的影响,分析了土壤各级团聚体不同形态氮库分配特征以及团聚体氮库与土壤氮素矿化之间的关系.结果表明:1各样地土壤团聚体全氮、轻组氮、碱解氮、矿质氮含量基本上随团聚体粒径减小而升高,峰值出现在0.25 mm粒径.除矿质氮外,各种氮形态在不同样地之间,总体上表现为弃耕地草地灌丛地灌乔林地乔木林地、人工金银花地人工林地.2各粒径团聚体有机氮库容量受团聚体粒径质量分数控制,其中5~10mm、2~5 mm粒径团聚体有机氮库容量较大,土壤氮主要贮存于大团聚体中,大团聚体对土壤碳、氮的贮存有重要意义.3团聚体全氮贮量中,0.25~1 mm、5~10 mm、2~5 mm粒径对土壤净氮矿化量贡献大,其它粒径贡献较小.随植被恢复进程,土壤中5 mm粒径团聚体质量分数逐渐提高,大团聚体氮贮量相应提高,在增强土壤供氮能力的同时,加强了对有机氮的贮存与保护.     

Relationships between dissolved and particulate carbohydrate temporal patterns and mucilaginous aggregates formation: evidences from time series analysis and biochemical composition of aggregates

A 3-year monitoring of dissolved and particulate carbohydrate concentrations in four transects located in the Adriatic and Tyrrhenian Seas was performed in order to get information on the role played by carbohydrates in the mucilage formation in these areas. The application of time series analysis pointed out that the concentration of dissolved carbohydrates does not vary significantly in coincidence of the mucilage appearance showing an almost constant state with respect to time. In contrast, wider temporal variations of carbohydrate amounts, either increase or decrease, were observed when mucilages were lacking or reduced. This almost constant state of carbohydrate amounts observed in presence of mucilages that we define 'steady state' could be associated to an alteration of the complex chemical equilibrium between synthesis and degradation (either hydrolysis or oxidation) reactions of the organic polymers which are typical of the humification processes in the marine environment. The results of this study suggest that the monitoring of carbohydrates can represent an useful tool for the comprehension of the most relevant phenomena of mucilage appearance in the Northern Adriatic Sea.     

岩溶与非岩溶区水稻土团聚体细菌群落结构和功能类群比较

研究岩溶与非岩溶区土壤团聚体中微生物群落结构和功能类群异同,可以为揭示岩溶区土壤有机微生物与团粒结构稳定之间的互作机制提供理论依据.以岩溶与非岩溶稻田的耕层土壤为研究对象,采用湿筛法将团聚体分为大团聚体(0.25～2 mm)、微团聚体(0.053～0.25 mm)和粉、黏粒组分(<0.053 mm),通过高通量测序对土壤团聚体微生物群落结构进行分析,并采用共现网络分析细菌关键类群以及利用FAPROTAX进行功能预测.结果表明,(1)岩溶区大团聚体质量占比为30.94%,团聚体平均质量直径和几何平均直径分别为0.41 mm和0.15 mm,这3个项目均显著高于非岩溶区,表明岩溶区的环境有利于团聚体的形成;(2)岩溶区3个粒径团聚体的酸杆菌门、变形菌门、酸杆菌(Gp3、 Gp4和Gp6)和鞘氨醇单胞菌属等相对丰度均高于非岩溶区.岩溶区微团聚体中的绿弯菌门的相对丰度(6.13%)显著高于粉、黏粒组分(2.79%);(3)共现网络分析表明,变形菌门和酸杆菌门为3个粒径团聚体中的关键类群.岩溶区微团聚体中细菌正相关边(65.5%)最高,相互关系多为协同关系;(4)岩溶区土壤3个粒径团聚体中...     

Energy and CO2 from high performance recycled aggregate production

The use of recycled concrete aggregates (RCA) in applications other than road sub-layers is limited by two factors: the high porosity of RCA in comparison with natural aggregates, and the restrictions set forth in standards and building codes. Research efforts aimed at alleviating these restrictions are focused on improving the quality of coarse RCAs by reducing the amount of adhered cement pastes, which is the weakest element in this system and influences the rheological behaviour.This paper presents an analysis of the environmental impacts of the recent mechanical and thermo-mechanical processing techniques which produce high performance RCA by reducing the volume of adhered cement paste. Based on published data, processing scenarios were established. These scenarios permit making rough estimates of energy consumption, CO₂ emissions, fines generation and product quality. Using these data and the available emission factors from several countries, an objective comparison was made between these innovating processes and conventional recycling.The production of fines increases from 40% up to as much as 70% as the volume of adhered cement paste on the RCA is reduced. Fuel fed thermo-mechanical process energy consumption, per tonne of recycled aggregate, varies between 36 and 62 times higher than conventional recycling processes. Mechanical processing, combined with microwave heating, increases energy consumption from 3 to a little more than 4 times conventional recycling. Consequently, CO₂ emissions released by conventional coarse aggregate production go from 1.5 to 4.5 kgCO₂/t, to around 200 kgCO₂/t, for that of fossil fuel fed thermo-mechanical treatments.Mechanical and mechanical/microwave treatments appear to have the greatest environmental potential. Notwithstanding, the further development of markets for fines is crucial for reducing environmental loads.     

Behavior of aqueous stable colloidal nano-C60 aggregates exposed to TX100 micelles under different environmental conditions

C₆₀, as one of carbon nanomaterials widely used in various fields, could be released into the water environment thus exerting some potential health risks to human beings. This work examined the behavior of aqueous stable colloidal nano-C₆₀ (nC₆₀) aggregates under different environmental conditions including Polyethylene glycol octylphenol ether (TX100) micelles concentration, pH, and reaction time when exposed to TX100 micelles. Results show that the nC₆₀ aggregates became more dispersive and restored the capability of generating the singlet oxygen when exposed to TX100 micelles. With the increase of TX100 concentration, smaller average size of nC₆₀ aggregates was observed in dynamic light scattering (DLS) analysis, the fluorescence intensity of TX100 was more quenched by nC₆₀ aggregates, and the kinetic rate constant of generating the singlet oxygen for nC₆₀ aggregates was improved. The mean size of nC₆₀ aggregates in the presence of TX100 had no obvious variations when the pH ranged from 4 to 8. The longer reaction time between nC₆₀ aggregates and TX100 led to a higher kinetic rate constant of generating the singlet oxygen. Collective data suggest that variations in physicochemical properties of nC₆₀ aggregates are strongly dependent on the surrounding media under different environmental conditions and directly govern nC₆₀’s transport behavior and potential toxicity.     

Recovery of copper from small grain size fractions of municipal solid waste incineration bottom ash by means of density separation

Small grain size fractions of municipal solid waste incineration (MSWI) bottom ash (BA) contain elemental and chemically bonded metals in appreciable amounts, especially copper. Investigations with a centrifugal concentrator were carried out using samples, which had been treated with different impact devices. Partly the impacts of single devices were visible in outlines, but mostly the surfaces of the metals were still covered with mineral residues. To generate copper rich fractions, parameters of the separation process should ensure mass yields <2%, best between 0.5 and 1%. The density of the concentrates is then generally >3.2 g/cm³. Best results were achieved with material from a special treatment train which is adapted to grain sizes <2 mm. Reliable copper contents between 20 and 40% (single runs >50%) could be realised. However, considering the required mass yields, referred to this subset only 150–170 g copper would be recovered from 1 Mg MSWI BA. Furthermore, this copper is only in parts present in elemental form. A dependable added value of such treatment step seems to be given only, if that enables a recycling of the mineral aggregates (tailings) in parallel to avoid landfill costs.     

水稻秸秆还田对福州平原稻田土壤水稳性团聚体分布及稳定性影响

为阐明早稻与晚稻生长期土壤水稳性团聚体分布及其稳定性对秸秆还田的响应,以福州平原红壤水稻田为研究对象,对秸秆还田后早稻田和晚稻田土壤水稳性团聚体分布特征及其稳定性,包括粒径0.25 mm团聚体的百分含量R0.25、平均质量直径(MWD)、平均几何直径(GMD)和分型维数(D)进行测定与分析.研究结果表明,秸秆还田和对照样地,0~40 cm土层中早稻与晚稻生长期土壤均表现为水稳性团聚体组成以微团聚体(0.25 mm粒级团聚体)为主,团聚体粒级越大,含量越少;秸秆还田对0~40 cm土层中早稻田土壤水稳性大团聚体和微团聚体总含量的影响均不显著,但秸秆还田显著增加了晚稻田土壤水稳性大团聚体(粒径0.25 mm)含量(p0.05),并显著减少了土壤水稳性微团聚体含量(p0.05);秸秆还田对早稻田土壤水稳性团聚体MWD、GMD和D值影响均不显著,但显著增加了晚稻田土壤水稳性团聚体MWD和GMD值,显著降低了土壤水稳性团聚体D值(p0.05);秸秆还田对早稻田土壤水稳性团聚体稳定性影响不显著,但显著增加了晚稻田土壤水稳性团聚体稳定性(p0.05).