Winter survival of microbial contaminants in soil: An in situ verification

The aim of the research was to evaluate, at site scale, the influence of freezing and freeze/ thaw cycles on the survival of faecal coliforms and faecal enterococci in soil, in a climate change perspective. Before the winter period and during grazing, viable cells of faecal coliforms and faecal enterococci were detected only in the first 10 cm below ground, while, after the winter period and before the new seasonal grazing, a lower number of viable cells of both faecal indicators was detected only in some of the investigated soil profiles, and within the first 5 cm. Taking into consideration the results of specific investigations, we hypothesise that the non-uniform spatial distribution of grass roots within the studied soil can play an important role in influencing this phenomenon, while several abiotic factors do not play any significant role. Taking into account the local trend in the increase of air temperature, a different distribution of microbial pollution over time is expected in spring waters, in future climate scenarios. The progressive increase in air temperature will cause a progressive decrease in freeze/thaw cycles at higher altitudes, minimising cold shocks on microbial cells, and causing spring water pollution also during winter.     

Molecular characterization of microbial communities in bioaerosols of a coal mine by 454 pyrosequencing and real-time PCR

Microbial diversity and abundance in bioaerosols of a coal mine were analyzed based on 454 pyrosequencing and real-time polymerase chain reaction(PCR). A total of 37,191 high quality sequences were obtained and could be classified into 531, 1730 and 448 operational taxonomic units respectively for archaea, bacteria and fungi at 97% sequence similarity. The Shannon diversity index for archaea, bacteria and fungi was respectively 4.71, 6.29 and 3.86, indicating a high diversity in coal mine bioaerosols. Crenarchaeota, Proteobacteria and Ascomycota were the dominant phyla for archaea, bacteria and fungi, respectively. The concentrations of total archaea, bacteria and fungi were 1.44 × 108, 1.02 × 108 and 9.60 × 104cells/m3, respectively.Methanotrophs observed in bioaerosols suggested possible methane oxidation in the coal mine. The identified potential pathogens to coal miners, such as Acinetobacter schindleri,Aeromonas cavernicola, Alternaria alternata, Aspergillus penicillioides, Cladosporium cladosporioides,and Penicillium brevicompactum were also observed. This was the first investigation of microbial diversity and abundance in coal mine bioaerosols. The investigation of microbial communities would be favorable in promoting the progress of methane control based on microbial technique and concern on coal miners’ health.     

Salinity influence on soil microbial respiration rate of wetland in the Yangtze River estuary through changing microbial community

Estuarine wetland, where freshwater mixes with salt water, comprises different regions（rivers and marine ecosystems） with significantly varying tidal salinities. Two sampling areas, ZXS and JS, were selected to investigate the effect of tidal salinity on soil respiration（SR）. ZXS and JS were located in Zhongxia Shoal and Jiangyanan Shoal of Jiuduansha Wetland respectively, with similar elevation and plant species, but significantly different in salinity. The results showed that with almost identical plant biomass, the SR and soil microbial respiration（SMR） of the tidal wetland with lower salinity（JS） were significantly higher than those of the tidal wetland with higher salinity（ZXS）（p 〈 0.05）. However, unlike SMR and SR, the difference in the soil microbial biomass（SMB） was not significant（p 〉 0.05）with the SMB of ZXS a little higher than that of JS. The higher SMR and SR of JS may be closely connected to the soil microbial community structures and amount of dominant bacteria. Abundant β- and γ-Proteobacteria and Actinobacteria in JS soil, which have strong heterotrophic metabolic capabilities, could be the main reason for higher SMR and SR,whereas a high number of ε-Proteobacteria in ZXS, some of which have carbon fixation ability, could be responsible for relatively lower carbon output. Path analysis indicated that soil salinity had the maximum negative total influencing coefficient with SMR among the various soil physical and chemical factors, suggesting that higher soil salinity, restricting highly heterotrophic bacteria, is the principle reason for lower SMR and SR in the ZXS.     

微生物燃料电池的研究综述

微生物燃料电池是一种利用微生物的催化作用,将燃料中的化学能转化为电能,同时又可以处理废水的新型技术,具有显著的环境效益和经济效益。本文对微生物燃料电池的基本原理进行了详细的叙述,对一些影响微生物燃料电池在处理污水时发电的基本因素做了较全面的比较,同时也探讨了一些现阶段微生物燃料电池的瓶颈问题。展望了微生物燃料电池(MFCs)这一绿色技术的良好的发展前景。     

生物质絮凝剂在水处理中的应用研究进展

在水处理中,絮凝剂必不可少且种类繁多,现以无机及有机高分子絮凝剂使用最为广泛。但随着大众对于环境及水健康的关注度增大,其二者的毒性及难降解性使得大家将目光转向可实现无污染排放的绿色化絮凝剂-生物质絮凝剂。笔者在此就综述应用价值较高的几类生物质絮凝剂的研究进展,以期为理论研究和工程实践提供指导。     

Identification of a reactive degradation zone at a landfill leachate plume fringe using high resolution sampling and incubation techniques

Vertical small-scale variation in phenoxy acid herbicide degradation across a landfill leachate plume fringe was studied using laboratory degradation experiments. Sediment cores (subdivided into 5 cm segments) were collected in the aquifer and the sediment and porewater were used for microcosm experiments (50 experiments) and for determination of solid organic carbon, solid-water partitioning coefficients, specific phenoxy acid degraders and porewater chemistry. Results from a multi-level sampler installed next to the cores provided information on the plume position and oxygen concentration in the groundwater. Oxygen concentration was controlled individually in each microcosm to mimic the conditions at their corresponding depths. A highly increased degradation potential existed at the narrow plume fringe (37.7 to 38.6 masl), governed by the presence of phenoxy acids and oxygen. This resulted in the proliferation of a microbial population of specific phenoxy acid degraders, which further enhanced the degradation potential for phenoxy acids at the fringe. The results illustrate the importance of fringe degradation processes in contaminant plumes. Furthermore, they highlight the relevance of using high-resolution sampling techniques as well as controlled microcosm experiments in the assessment of the natural attenuation capacity of contaminant plumes in groundwater.     

微生物传感器技术原理及其在水环境监测中的应用

微生物传感器技术产生于７０年代，并且，已在水环境监测中得到应用，例如，ＢＯＤ、ＮＨ３、ＮＨ４＾＋、ＮＯ２＾－、ＮＯ３＾－等项目分析；毒物测定和毒性评价；致突变物的筛选等。实践证明，该项技术具有快速、灵敏、易于自动控制、成本低廉等优点；可以相信，它必定会越来越多的应用于环境监测。     

Bioremediation of Soil Degraded by Sewage Sludge: Effects on Soil Properties and Erosion Losses

Soils in the Mediterranean area are very prone to erosion due to the loss of organic matter and the consequent lack of protective vegetation. In this experiment a Mediterranean degraded soil with a 15% slope was amended at a rate of 250 t ha^–1 wet weight with sewage sludge and with a mixture of sewage sludge and barley straw (70% carbon from sewage sludge and 30% from the straw) in order to study their influence on soil structure recovery and hence the soilss resistance to erosion processes. Both types of organic amendment led to an improvement in several soil properties (physical, biological, and microbiological) as a result of the spontaneous growth plant covering that became evident three months after amendment. This vegetation remained throughout the two years of the experiment and prevented the water erosion processes that normally precede soil degradation. Amendment by sewage sludge alone reduced soil loss by 80% compared with the control soil, while the mixture that included both sewage sludge and barley straw reduced losses by 84%, both reducing runoff by 57%. The amended soils showed increases in the percentage of stable aggregates, the levels of the total and water-soluble C fractions, microbial biomass C, basal respiration, and the activity of the different enzymes involved in the biogeochemical cycles of C, N, and P. The results confirm the usefulness of sewage sludge as an organic amendment for recovering damaged soils.     

Novel approach to monitoring of the soil biological quality

In this study, a new approach to interpretation of results of the simple microbial biomass and respiration measurements in the soil microbiology is proposed. The principle is based on eight basal and derived microbial parameters, which are standardized and then plotted into sunray plots. The output is visual presentation of one plot for each soil, which makes possible the relative comparison and evaluation of soils in the monitored set. Problems of soil microbiology, such as the lack of benchmarking and reference values, can be avoided by using the proposed method. We found that eight parameters provide enough information for evaluation of the status of the soil microorganisms and, thus, for evaluation of the soil biological quality. The usage of rare parameters (potential respiration PR, ratio of potential and basal respiration PR/BR, biomass-specific potential respiration PR/C(bio), available organic carbon C(ext), and biomass-specific available organic carbon C(ext)/C(bio)) can be recommended, besides classical and well-known parameters (microbial biomass C(bio), basal respiration BR, metabolic coefficient qCO(2)). The combination of basal parameters and derived coefficients can also extend our knowledge about the condition of the soil microorganisms. In monitoring the case studies presented, we observed that soils evaluated to possess good biological quality displayed generally higher values of organic carbon, total nitrogen, clay, and cation exchange capacity. The soils of good biological quality can display higher levels of contaminants. This is probably related with the higher content of organic carbon and clay in these soils.     

生化需氧量(BOD)测定技术进展

综合评述了BOD5指标发展历程和测定方法,重点讨论了标准稀释法接种技术和微生物传感器方法研究的主要进展。