耐受自身代谢产物及耐二甲基亚砜红霉素高产菌株的选育

为提高红霉素发酵单位,考察了二甲基亚砜(DMSO)添加时间和体积分数对红霉素合成的影响,采用筛选自身代谢产物突变株的方法,将突变株进行常压室温等离子体(ARTP)诱变和耐受高浓度DMSO处理。结果显示,在36 h向发酵瓶中添加30000μg/m L红霉素,筛选得到化学效价比对照提高22.4%的菌株。DMSO最适添加时间为发酵48 h,最适添加剂量为0.2%,其可提高发酵单位10.1%。     

安徽省大气环境质量模糊综合评价

以二氧化硫（SO2）、二氧化氮（NO2）和可吸入颗粒物（PM10）作为评价因子,利用模糊综合评价法对安徽省大气环境质量进行了评价与分析.结果表明,可吸入颗粒物是安徽省的首要污染物,但铜陵市有所不同,首要污染物为二氧化硫.模糊综合评价显示,安徽省大气环境受到一定程度的污染,16个市中黄山市的大气环境综合质量最好.近年来,安徽省大气环境质量有所改善,但改善幅度较小.     

Thermal deactivation of high-affinity H2 uptake activity in soils

Soils are the most important sink for atmospheric hydrogen, which is assumed to be oxidized by abiontic soil hydrogenases or by putative high-affinity hydrogenases of microbial origin. The activity of soil hydrogenases has been found to change with soil temperature as it changes during the day and the season. However, it is unclear whether and to which extent the soil hydrogenases are deactivated by increased temperature. Therefore, we incubated soils from different climates and different ecosystems (forest, agricultural, arid, hyper-arid, paddy, peat) at elevated temperature and measured the residual activity at 25 °C after different incubation times. We found that at least part of the soil hydrogenase is deactivated irreversibly already at relatively low temperatures (>30 °C) and short exposure times (>10 min) and that the deactivation was more pronounced in soil from cold versus hot climate. The deactivation kinetics could be fitted to a biexponential model, but were complex with respect to soil type and deactivation temperature. The results show that new hydrogenase activity has to be generated in the soil to compensate for activity loss by diurnal and seasonally increased temperature.     

Tree species affect atmospheric CH4 oxidation without altering community composition of soil methanotrophs

Plant species exert strong effects on ecosystem functions and one of the emerging, and difficult to test hypotheses, is that plants alter soil functions through changing the community structure of soil microorganisms. We tested the hypothesis for atmospheric CH₄ oxidation by using soil samples from a Siberian afforestation experiment and exposing them to ¹³C-CH₄. We determined the activity of the soil methanotrophs under different tree species at three levels of initial CH₄ concentration (30, 200 and 1000 ppm) thus distinguishing the activities of low- and high-affinity methanotrophs. Half of the samples were incubated with ¹³C-enriched CH₄ (99.9%) and half with ¹²C-CH₄. This allowed an estimation of the amount of ¹³C incorporated into individual PLFAs and determination of PLFAs of methanotrophs involved in CH₄ oxidation at the different CH₄ concentrations. Tree species strongly altered the activity of atmospheric CH₄ oxidation without appearing to change the composition of high-affinity methanotrophs as evidenced by PLFA ¹³C labeling. The low diversity of atmospheric CH₄ oxidizers, presumably belonging to the UCSα group, may explain the lack of tree species effects on the composition of soil methanotrophs. We submit that the observed tree species effects on atmospheric CH₄ oxidation indicate an effect on biomass or cell-specific activities rather than by a community change and this may be related to the impact of the tree species on soil N cycling.     

Influence of tree crown characteristics on the local PM10 distribution inside an urban street canyon in Antwerp (Belgium): A model and experimental approach

Apart from influencing the amount of leaf-deposited particles, tree crown morphology will influence the local distribution of atmospheric particles. Nevertheless, tree crowns are often represented very rudimentary in three-dimensional air quality models. Therefore, the influence of tree crown representation on the local ambient PM₁₀ concentration and resulting leaf-deposited PM₁₀ mass was evaluated, using the three-dimensional computational fluid dynamics (CFD) model ENVI-met^® and ground-based LiDAR imaging. The modelled leaf-deposited PM₁₀ mass was compared to gravimetric results within three different particle size fractions (0.2–3, 3–10 and >10 μm), obtained at 20 locations within the tree crown. Modelling of the LiDAR-derived tree crown resulted in altered atmospheric PM₁₀ concentrations in the vicinity of the tree crown. Although this model study was limited to a single tree and model configuration, our results demonstrate that improving tree crown characteristics (shape, dimensions and LAD) affects the resulting local PM₁₀ distribution in ENVI-met. An accurate tree crown representation seems, therefore, of great importance when aiming at modelling the local PM distribution.     

大气氟化物对植物的伤害及其测试分析方法

介绍了氟的自然分布和特性,阐述了大气氟化物对植物的伤害症状、伤害机理,并论述了其测试分析方法。     

我国近地面甲烷浓度分布及变化规律

利用我国业务使用的5个大气本底监测站的观测资料,分析了2009年1月至2013年12月不同地区近地面甲烷(CH_4)浓度的分布和变化规律。结果表明:这5年临安站CH_4浓度最高,其次是龙凤山站,上甸子站居中,而香格里拉站和瓦里关站CH_4浓度最低。上甸子站和龙凤山站CH_4浓度具有明显的双峰特征,最高值出现在夏季,次高值出现在冬季;且受人为活动的影响,CH_4浓度日变化幅度很大。而香格里拉站和瓦里关站由于海拔高,人为排放源少,只有1个峰值出现在自然源排放强烈的夏季。除上甸子站CH_4浓度呈逐年略下降趋势外,其余4个站的CH_4浓度都呈逐渐上升趋势。     

Response of seedlings growth of Pinus sylvestriformis to atmospheric CO_2 enrichment in Changbai Mountain

IntroductionGIobaIchangehasbeenoneoftheimpoFtantis-suesandscientistspaycIoseattentiontoit.ThegreatimportanceofforestecosystemisreflectednotonlybytheirhUgebiomass,butaIsobytheirsignifi-cantroIeintheglobaIcarbonbaIance.Howtreesrespondtoclimaticchangesmightbeofgreatsig-nificance.ManystudiesindicatethattherisingatmosphericCo,leveIscanmakeasubstantialeffectonplantgroWthanddevelopment.SomeonethinkcommonlythattherisingCo,levelscanstimuIatepIantgroWthandbiomassproduction,sincephotosynthesisofC…     

Bimodal grain-size distribution of Chinese loess, and its palaeoclimatic implications

Grain-size analysis indicates that Chinese loess generally shows a bimodal distribution with a coarse and a fine component. The coarse component, comprising the main part of the loess, has pronounced kurtosis and is well sorted, which is interpreted to be the product of dust storms generated by low-altitude northwesterly winds. Its grain-size reflects the strength of the low-altitude circulation in the dust seasons of the year, and its percentage provides an indicator of the source area aridity and the frequency of dust storms. Conversely, the fine component has a wide grain-size range and is poorly sorted. Sedimentary illustrations based on the grain-size distribution characteristics of bulk samples and of detrital quartz suggest that the fine component probably represents the background dust load of the atmosphere and is mainly transported by high-altitude westerly airstreams. Its grain-size provides an estimate of the westerly air stream intensity. The coarse and fine components of a loess sample can be mathematically separated by fitting a designated mathematical distribution function to the measured grain-size data, and this procedure constitutes an approach for reconstructing the palaeowind system of Northern China.     

Impact of atmospheric CO2 and plant life forms on soil microbial activities

From the global change perspective, increase of atmospheric CO₂ and land cover transformation are among the major impacts caused by human activities. In this study, we are addressing the combined issues of the effect of CO₂ concentration increase and plant type on soil microbial activities by asking how annual and perennial plant groups affect soil microbial processes under elevated CO₂. The experimental design used a mix of species of different growth forms for both annuals and perennials. Our objective was: (1) to determine how two years of annual or perennial plant cover and CO₂ enrichment could affect Mediterranean soil microbial processes; (2) to test the resistance and the resilience of these soil functional processes after a natural perturbation. We determined the effects of 2 years atmospheric CO₂ enrichment on soil potential respiration (SIR), denitrification (DEA) and nitrification (NEA) activities. We could not find any significant effect of CO₂ increase on SIR, DEA and NEA. However, we found a strong effect of the plant cover type, i.e. annuals versus perennials, on the potential microbial activity related to N cycling. DEA and NEA were significantly higher in soil under annual plants while SIR was not significantly different. To determine whether these changes would survive a natural perturbation, we carried out a rain event experiment once the experimental treatments (i.e. different plant cover and atmospheric CO₂ concentration) were stopped. The soil potential respiration, as expressed by the SIR, was not affected and remained stable. DEA rates converged rapidly under annuals and perennials after the rain event. Under both annuals and perennials NEA increased significantly after the rain event but remained significantly higher in the soil with annual plants. The relative change of the soil microbial processes induced by annual and perennial plants was inversely related to the density and the diversity of the corresponding microbial functional groups.