不同释钾菌对粉煤灰的生态效应

粉煤灰治理难度大,但它含有植物生长必需的营养元素钾,将其就地资源化生物利用是一条较好的途径。释钾菌是一种能把矿物中的难溶性钾转化为有效钾的细菌,从土壤中筛选出2种释钾菌,经过在粉煤灰基质中的驯化培养,通过盆栽试验种植紫花苜蓿,比较不同菌株对粉煤灰的改良作用及其对植物生长的影响。结果表明,筛选出的菌株C6对粉煤灰中速效钾的释放效果明显,降低了基质pH,显著地促进了植物的生长,对粉煤灰生态修复具有重要意义。     

Response of organic aerosol characteristics to emission reduction in Yangtze River Delta region

● The emission reduction causes significant change in organic aerosol composition. ● The atmospheric oxidizing capacity improved during emission reduction. ● The mixed oxygenated organic aerosol contributed higher during emission reduction. Organic aerosol (OA) is a major component of atmospheric particulate matter (PM) with complex composition and formation processes influenced by various factors. Emission reduction can alter both precursors and oxidants which further affects secondary OA formation. Here we provide an observational analysis of secondary OA (SOA) variation properties in Yangtze River Delta (YRD) of eastern China in response to large scale of emission reduction during Chinese New Year (CNY) holidays from 2015 to 2020, and the COVID-19 pandemic period from January to March, 2020. We found a 17% increase of SOA proportion during the COVID lockdown. The relative enrichment of SOA is also found during multi-year CNY holidays with dramatic reduction of anthropogenic emissions. Two types of oxygenated OA (OOA) influenced by mixed emissions and SOA formation were found to be the dominant components during the lockdown in YRD region. Our results highlight that these emission-reduction-induced changes in organic aerosol need to be considered in the future to optimize air pollution control measures.     

The Behaviour of Selenium in Geological Processes

Selenium contents were analyzed from a total of 244 soil samples collected over different rock types at a sampling density of one sample per 4km² around Geita gold mining areas, Northwestern Tanzania. Comparisons using literature survey contents of selenium in geological materials and some implications on the selenium in soils are compiled and discussed. Most selenium occurs as simple selenides in small quantities in low temperature hydrothermal deposits devoid of sulphur. It has been observed that to a large extent selenium content is increased more than most trace elements in the upper parts of the Earth perhaps through extraterrestrial deposition. In deep-seated rocks selenium is associated with sulphur but being volatile selenium and sulphur do not behave according to the crystallochemical law. Due to the higher stability of S⁶⁺, Se⁴⁺ and Se⁰ separate during migration. Thus, selenium is especially found in deep-seated plutonic rocks where large magma bodies cooled slowly and sulphur is available to precipitate sulphides. Selenium, which occurs with sulphides, is inhomogeneously deposited into continental margins. It is increased during magmatic differentiation and is highest in basic rocks. In magmatic and metamorphic conditions, selenium is found in the crystal structures of sulphides while in pneumatolytic and hydrothermal processes, it is relatively enriched into the late differentiates compared to sulphur. In metamorphic rocks selenium is more widely distributed. Selenium content in soils in the investigated area varies from (0.3–0.5gg^–1) in laterite and in black cotton soil 0.4gg^–1. Of all volcanic rocks selenium is highest in volcanogenic rocks especially the basalts. Surface waters are enriched in selenium, which they leach from volcanic materials. Selenium in sediments containing clay and organic matter is elevated but the content decreases with increased metamorphism. Selenium in volcanic areas can be used as a pathfinder in prospecting for volcanogenic ore deposits. S/Se ratios are distinct in different rock types and can thus be used to elucidate the origin of rocks, ores, and sediments.     

高Cu、高Zn对白星花金龟幼虫的毒性作用

Cu(铜)和Zn(锌)是环境中最常见的重金属污染元素,为探究其对白星花金龟幼虫的毒性,采用滤纸接触法、人工土壤法和菌渣培养法研究了高Cu、高Zn对白星花金龟幼虫的生长及氧化胁迫效应。结果表明,滤纸接触法和人工土壤法中试验浓度Cu、Zn对白星花金龟幼虫死亡率无明显影响。菌渣培养法中虫体的取食抑制率和体重增长抑制率均与Cu、Zn浓度呈显著性正相关关系;Cu处理诱导了虫体可溶性蛋白含量的增加,抑制了SOD(超氧化物歧化酶)、GST(谷胱甘肽转移酶)的活性和MDA(丙二醛)的产生,对CAT(过氧化物酶)活性没有显著影响;Zn浓度为3 500和5 000 mg·kg-1的处理组可溶性蛋白含量被显著诱导、MDA含量被显著抑制,浓度为2 000和6 500 mg·kg-1处理组的SOD活性被激活(P0.05),Zn胁迫未对CAT、GST活性造成明显影响。表明Cu、Zn污染对白星花金龟幼虫生长具有毒性效应,在评价高浓度的重金属污染对虫体的毒性作用时,不能仅采用SOD、CAT、GST等指标作为标志物,需要综合其他指标进行分析。     

三丁基锡对孔雀鱼的毒性效应研究

采用静态暴露方式研究三丁基锡氯化物(TBTCl)对孔雀鱼的毒性效应.当幼鱼暴露于1.25-7.90μg·l-1的TBTCl 后,出现明显的急性中毒症状,96h的半致死浓度(LC50)为5.82μg·l-1; 成鱼在0.14-3.56μg·l-1浓度下暴露10-30d,TBTCl能诱导雌鱼的肝体指数升高,并使肝脏和脾脏组织的显微结构发生明显的病理变化,毒害作用具有明显的剂量-效应和时间-效应关系.表明肝体指数以及肝脏、脾脏等组织的病理学变化可以作为评估三丁基锡等环境污染物的生物指标.     

廊道效应与城市景观结构

根据景观学原理，本文将城市廊道分为两类，人工廊道与自然廊道，并着重分析城市廊道的场效应，研究表明，廊道效应产生的实质在于廊道效益是距离的函数，因而可用指数衰减曲线表示，从理论上分析，人工廊道与自然廊道场效应的分界点即综合效益极大点，自然廊道在两条人工廊之间存在的合理依据是：至少存在两个分别与两条指数衰减曲线相交的综合效益极值点。根据廊道效应原 文对北京古代传统规划格局进行分析，发生在天人鸽 与择中     

Exploration of relationships between phytoplankton biomass and related environmental variables using multivariate statistic analysis in a eutrophic shallow lake： A S-year study

Understanding the process of the changing phytoplankton patterns can be particularly useful in water quality improvement and management decisions. However, it is generally not easy to illustrate the interactions between phytoplankton biomass and related environmental variables given their high spatial and temporal heterogeneity. To elucidate relationships between them, in a eutrophic shallow lake, Taihu Lake, relative long-term data set of biotic and abiotic parameters of water quality in the lake were conducted using multivariate statistical analysis within seasonal periodicity. The results indicate that water temperature and total phosphorus （TP） played governing roles in phytoplankton dynamics in most seasons （i.e. temperature in winter, spring and summer; TP in spring, summer and autumn）; COD （chemical oxygen demand） and BOD （biological oxygen demand） presented significant positive relationships with phytoplankton biomass in spring, summer and autumn. However, a complex interplay was found between phytoplankton biomass and nitrogen considering significant positive relationships occurring between them in spring and autumn, and conversely negative ones in summer. As the predatory factor, zooplankton presented significant grazing-pressure on phytoplankton biomass during summer in view of negative relationship between them in the season. Significant feedback effects of phytoplankton development were identified in summer and autumn in view that significant relationships were obser,qed between phytoplankton biomass and pH, Trans （transparency of water） and DO. The results indicate that interactions between phyto：plankton biomass and related environmental variables are highly sensitive to seasonal periodicity, which improves understanding of different roles of biotic and abiotic variables upon phytoplankton variability, and hence, advances management methods for eutrophic lakes.     

基于PM2.5站点监测数据的京津冀AOD补值研究

以京津冀2020年318个地面监测站点的PM_2.5数据为估算因子,构建了时空线性混合效应模型(STLME)和时空嵌套线性混合效应模型(STNLME),为AOD数据的补值研究提供了一种新方法.结果表明:在有AOD-PM_2.5匹配数据的日期,上述两个模型估算精度相近,交叉验证后决定系数R²分别为0.868和0.874,均方根误差RMSE分别为0.112和0.109;在无AOD-PM_2.5匹配数据的日期,嵌套模型估算精度明显高于非嵌套模型,交叉验证后决定系数R²分别为0.63和0.26.经过模型补值后,研究区监测站点所在网格AOD数据空间维有效比率从原始数据的44.35%提高到99.35%,时间维有效比率从87.94%提高到100%;同时,每个站点的年均AOD值都有明显提高,弥补了高PM_2.5浓度条件下缺失的AOD数据,可以减少空气污染和健康研究中暴露评估的偏差.     

藻形态及混凝剂组成对混凝-超滤过程的影响

为了保证藻类暴发阶段优质的饮用水供应,提高藻类的去除率,缓解藻类对水处理过程的影响,本研究以铜绿微囊藻(蓝藻)、小球藻(绿藻)和小环藻(硅藻)这3种不同形态藻细胞为研究对象,使用了3种具有不同铝形态分布的混凝剂[Al_2(SO_4)_3(AS)、Al_(13)、Al_(30)]进行混凝-超滤实验.在分离胞外有机物(EOM)的情况下,考察混凝过程中絮体的特性(粒径,强度因子,恢复因子)以及不同条件下形成的絮体对膜通量的影响.结果表明Al_(13)与Al_(30)的混凝作用以静电簇作用为主导,AS主要是以电中和作用为主导.对于铜绿微囊藻与小球藻体系,由于藻颗粒表面存在一定的凹陷,当Al_(13)与Al_(30)做混凝剂时,在投加量较低的情况下,吸附在颗粒表面凹陷处的混凝剂“失活”,其他部位由于仍带有一定的负电荷而造成絮体形成不明显,而AS做混凝剂时,混凝机制主要是电中和作用,可以明显降低颗粒之间的排斥力,在较低投加量下即可形成絮体.对于小环藻体系,由于其藻细胞呈现光滑的表面,Al_(13)与Al_(30)可有效发挥其静电簇作用机制,絮体在较低投加量下即可有效形成.膜通量与絮体粒径有明显的相关性,絮体粒径越大,超滤过程中形成的沉积层越疏松,膜比通量越大.     

Preparation, characterization, and photocatalytic activities of boron- and cerium-codoped TiO2

Boron- and cerium-codoped TiO2 photocatalysts were synthesized using modified sol-gel reaction process and characterized by X- ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, particle size distribution （PSD）, diffuse reflectance spectra （DRS）, and Brunauer-Emmett-Teller （BET）. The photocatalytic activities were evaluated by monitoring the degradation of dye Acid Red B （ARB）. The results showed that the prepared photocatalysts were mixed oxides mainly consisting of titania, ceria, and boron oxide. The structure of TiO2 could be transformed from amorphous to anatase and then to rutile by increasing calcination temperature; the transformation being accompanied by the growth of particle size without any obvious change in phase structure of CeO2. The XPS of B1.6Ce1.0-TiO2 prepared at 500℃ showed that a few boron atoms were incorporated into titania and ceria lattice, whereas others existed as B2O3. Cerium ions existed in two states, Ce^3＋ and Ce^4＋, and the atomic ratio of Ce^3＋/Ce^4＋ was 1.86. When boron and cerium were doped, the UV-Vis adsorption band wavelength showed an obvious shift toward the visible range （〈526 nm）. As the atomic ratio of Ce/Ti increased to 1.0, the absorbance edge wavelength increased to 481 nm. The absorbance edge wavelength decreased for higher cerium doping levels （Ce/Ti=2.0）. The particles size ranged from 122 to 255 nm with a domain at 168 nm （39.4%）. The degradation of ARB dye indicated that the photocatalytic activities of boron- and cerium-codoped TiO2 were much higher than those of P25 （a standard TiO2 powder）. The activities increased as the boron doping increased, whereas decreased when the Ce/Ti atomic ratio was greater than 0.5. The optimum atomic ratio of B/Ti and Ce/Ti was 1.6 and 0.5, respectively.