促进植物生长根圈细菌(PGPR)的研究现状

有机农业提倡与自然共存不破坏平衡,而自然界的土壤中存在许多可促进植物生长的植物根圈微生物(plant growth promoting rhizobacteria,PGPR),此类微生物可分泌促进植物生长的物质,并可诱导植物产生抗性基因,增强植物抗病.PGPR可产生有机物质促进植物生长,改善土壤肥力,增加可溶性磷及铁,诱发植物抗病、克服逆境、增强营养吸收,固氮或防治病害等,在有机农业上有助于植物增产,改善农业对化学肥料的依赖,生产出健康的作物.参25.     

改性腐殖酸对铀的吸附的试验研究

通过静态吸附实验,探讨了改性HA对U(Ⅵ)吸附影响。考查pH值、时间、U(Ⅵ)的初始浓度和温度等对吸附的影响。结果表明:pH值对改性腐殖酸的吸附效果影响较大,改性腐殖酸吸附U(Ⅵ)的最佳pH值为6,最大去除率为99.37%,吸附在60 min内基本达到平衡。UO22+在改性腐殖酸上的吸附是放热过程,符合Freundlich等温吸附方程,相关系数达0.99以上,表明IHA对铀的吸附是以表面为主要吸附位,并不是均匀的单层吸附。图8,参9.     

尖山河小流域土壤可蚀性K值空间变异研究

小流域尺度的土壤可蚀性 K 值空间分异特征及其与土地利用、植被类型、土壤理化性质等相关关系的研究,可以为小流域土壤侵蚀定量研究及综合治理决策提供科学依据。以云南省抚仙湖库区尖山河小流域为研究区,在大密度土壤采样和土壤理化性质测试分析的基础上,采用EPIC模型K值计算方法、地统计学方法和Kriging空间插值方法,计算分析了尖山河小流域土壤可蚀性K值的空间变异特征及土地利用/植被覆盖对K值的影响作用。结果表明,（1）研究区K值变化范围为0.1628-0.3836,均值为0.2824,中值为0.2885,均值与中值相近似,表明K值分布较均匀;变异系数为17.98%, K值存在中等程度的空间变异性。（2）不同土壤质地类型的K值存在一定差异,研究区主要土壤质地类型K值从大到小依次为粉壤〉壤土〉粘壤〉砂壤。（3）研究区以中可侵蚀性（0.25-0.30）、中高可侵蚀性（0.30-0.35）和中低可侵蚀性（0.20-0.25）土壤为主,面积分别为1797.88 hm2、1185.51 hm2和542.32 hm2,分别占小流域总面积的50.76%、33.47%和15.31%,而高可侵蚀性（〉0.35）土壤和较低可侵蚀性（0.15-0.20）土壤分布面积较少,无低可侵蚀性（〈0.15）土壤;在空间分布上,北部高山区土壤具有中低可侵蚀性,中、南部的低海拔区土壤具有中高可侵蚀性,中、南部其余区域土壤具有中可侵蚀性,这种空间分布与海拔存在较强的相关关系。（4）土地利用/植被覆盖对K值具有明显的影响作用,研究区主要土地利用/植被覆盖类型 K 值从小到大依次为林地〈灌草地〈荒草地〈旱平地〈园地〈旱坡地〈水田,需频繁松土、除草、耕作和扰动的土地利用/植被覆盖类型（园地、旱坡地、旱平地和水田）其K值较大,而无需耕作、扰动小的土地利用/植被覆盖类型（林地、荒草地和灌草地）其K值较小,这表?     

入侵植物南美蟛蜞菊营养器官的形态解剖研究

南美蟛蜞菊（Wedelia trilobata（L.）Hitchc.）是华南地区常见的入侵植物之一,其环境适应性强,繁殖速度快,对入侵地生态环境的破坏而导致生物多样性丧失的危害现象已经引起关注。结构与功能的相适应是生物学的基本观点之一,对入侵植物营养器官的内部形态解剖结构的研究,是理解入侵能力与其生物特性之间关系的直接路径,同时也是其他生理机理研究的结构基础。为研究入侵植物南美蟛蜞菊营养器官内部形态结构与其入侵能力的适应性,采用常规徒手切片技术对其根、茎及成熟叶片3大营养器官进行解剖及显微观察。结果表明：南美蟛蜞菊根、茎均具有次生结构。根韧皮部外方薄壁细胞具有分泌道,次生结构横切面中央为发达的次生木质部所填充,周皮代替表皮起保护作用,根的初生生长时期长,具有次生生长可视为其入侵定居时与本地物种形成地下资源和空间竞争的结构基础;茎的初生结构分化不久即产生次生结构,次生结构中央有明显的髓,次生维管束组织产生于初生结构的维管束之间并形成一管状结构明显将皮层和髓分开,茎内部组织高度木质化可视为是其茎直立生长及竞争地上资源和空间的结构基础;叶片为异面叶,上下表皮均具有气孔器和表皮毛,叶片内部具有分泌道,维管束发达且具有束鞘延伸,能与叶片表皮细胞共同构成辅助输导系统,叶片的结构特征是构成其喜阳植物的基础。此外叶片及根分泌道的存在可能与其化感物质的分泌有关。研究结果丰富了南美蟛蜞菊入侵适应性研究的背景基础,同时也弥补其在形态结构研究中的空缺。     

Experimental and computational assessment of 1,4-Dioxane degradation in a photo-Fenton reactive ceramic membrane filtration process

• 1,4-Dioxane was degraded via the photo-Fenton reactive membrane filtration. • Degradation efficiency and AQY were both enhanced in photocatalytic membrane. • There is a tradeoff between photocatalytic degradation and membrane permeation flux. • Degradation pathways of 1,4-Dioxane is revealed by DFT analysis. The present study evaluated a photo-Fenton reactive membrane that achieved enhanced 1,4-Dioxane removal performance. As a common organic solvent and stabilizer, 1,4-Dioxane is widely used in a variety of industrial products and poses negative environmental and health impacts. The membrane was prepared by covalently coating photocatalyst of goethite (α-FeOOH) on a ceramic porous membrane as we reported previously. The effects of UV irradiation, H₂O₂ and catalyst on the removal efficiency of 1,4-Dioxane in batch reactors were first evaluated for optimized reaction conditions, followed by a systematical investigation of 1,4-Dioxane removal in the photo-Fenton membrane filtration mode. Under optimized conditions, the 1,4-Dioxane removal rate reached up to 16% with combination of 2 mmol/L H₂O₂ and UV₃₆₅ irradiation (2000 µW/cm²) when the feed water was filtered by the photo-Fenton reactive membrane at a hydraulic retention time of 6 min. The removal efficiency and apparent quantum yield (AQY) were both enhanced in the filtration compared to the batch mode of the same photo-Fenton reaction. Moreover, the proposed degradation pathways were analyzed by density functional theory (DFT) calculations, which provided a new insight into the degradation mechanisms of 1,4-Dioxane in photo-Fenton reactions on the functionalized ceramic membrane.     

Assessment of heavy metal pollution and health risks in a main river in Huayuan County,Xiangxi, Hunan Province北大核心CSCD

To study heavy metal pollution and assess the health risk of river water in Huayuan County, Xiangxi, Hunan Province, 11 water samples were collected from the Huayuan River and Brother Rivers in August and December 2016. Heavy metal (Pb, Zn, Cr, Cu, Fe, and Ni) concentrations were determined from the samples. The health risk assessment model recommended by the U.S. Environmental Protection Agency (USEPA) was applied to assess the health risk of heavy metals in the main surface waters of Huayuan County. The results indicated that the concentrations of heavy metals (Pb, Zn, Cr, Cu, Fe, and Ni) of surface water in the research area were 2.57 × 10-3, 4.66 × 10-4, 1.65 × 10-3, 6.27 × 10-4, 0.19, and 8.50 × 10-4 mg/L, respectively. The health risk of surface waters with heavy metals was high. Therefore, the chemical carcinogenic substance (Cr) health risk index was five or six times higher than that of chemical non-carcinogens (Pb, Zn, Cu, and Ni). The average health risk indices of non-carcinogenic substances were in the order Pb > Cu > Zn > Ni. The correlation and principal component analysis of surface water showed that the six heavy metal elements were composed of three main components in the main surface waters of the county. The first principal component was comprised of Fe and Ni (33.28%), which was mainly from internal pollution. The second component was comprised of Cu and Cr (26.98%), which was primarily due to industrial waste water, rainwater leaching mineral waste produced by heavy metal mining, and smelting enterprises. The third component, resulting from geochemical pollution, was Zn (17.10%). The health risk indices triggered by heavy metal in surface waters was high. Heavy metal pollutants in the research area need to be controlled in the order Cr, Pb, Cu, Zn and Ni. © 2018 Science Press. All rights reserved.     

HEPA空气净化器对学校室内颗粒物的净化效果研究

为了解HEPA（high efficiency particle air filter,高效空气过滤器）空气净化器在小学教室和寝室的净化效果,于2019年3—4月在北京市一所全寄宿小学开展了一项HEPA空气净化器的交叉干预研究.记录干预组、非干预组室内和室外PM_2.5、PM₁₀、PM₁的浓度,计算空气净化器的净化率;采用多元线性回归模型探索净化效果的影响因素.结果表明:①空气净化器对PM_2.5、PM₁₀、PM₁的净化率分别为41.3%〔Q_l~Q_u（下四分位数~上四分位数,下同）:0~53.1%〕、40.7%（10.5%~46.2%）和34.9%（9.6%~40.3%）,其中对PM_2.5的净化率最高;寝室的净化率高于教室的净化率.②当室外PM_2.5浓度为[115,150）μg/m3时对PM_2.5的净化率最高,为52.83%（50.26%~56.13%）,PM₁₀和PM₁亦有类似结果.③多元线性回归分析表明,室外PM_2.5浓度 < 35 μg/m3时,开门通风和室内人员活动分别使室内PM_2.5浓度下降3.73 μg/m3〔95%置信区间（95% CI）:（0.60 μg/m3,6.86 μg/m3）〕和升高3.4 μg/m3（0.22 μg/m3,6.58 μg/m3）;室外PM_2.5浓度为[35,150）μg/m3时,空气净化器使室内PM_2.5浓度下降33.36 μg/m3（16.47 μg/m3,50.25 μg/m3）;室外PM_2.5浓度≥150 μg/m3时,空气净化器和开门通风分别使室内PM_2.5浓度下降48.87 μg/m3（25.62 μg/m3,72.12 μg/m3）和升高37.65 μg/m3（5.60 μg/m3,69.69 μg/m3）.研究显示:空气净化器可同时降低室内PM_2.5、PM₁₀、PM₁的浓度;当室外PM_2.5浓度 < 35 μg/m3时,不需开启空气净化器;当室外PM_2.5浓度为[35,150）μg/m3时,空气净化器有较好的净化效果,偶尔开窗通风不影响空气净化器的净化效果;当室外PM_2.5浓度≥150 μg/m3时,开启空气净化器时应关闭门窗,以免影响其净化效果.      

Meta-analysis of susceptibility of woody plants to loss of genetic diversity through habitat fragmentation

Shrubs and trees are assumed less likely to lose genetic variation in response to habitat fragmentation because they have certain life-history characteristics such as long lifespans and extensive pollen flow. To test this assumption, we conducted a meta-analysis with data on 97 woody plant species derived from 98 studies of habitat fragmentation. We measured the weighted response of four different measures of population-level genetic diversity to habitat fragmentation with Hedge's d and Spearman rank correlation. We tested whether the genetic response to habitat fragmentation was mediated by life-history traits (longevity, pollination mode, and seed dispersal vector) and study characteristics (genetic marker and plant material used). For both tests of effect size habitat fragmentation was associated with a substantial decrease in expected heterozygosity, number of alleles, and percentage of polymorphic loci, whereas the population inbreeding coefficient was not associated with these measures. The largest proportion of variation among effect sizes was explained by pollination mechanism and by the age of the tissue (progeny or adult) that was genotyped. Our primary finding was that wind-pollinated trees and shrubs appeared to be as likely to lose genetic variation as insect-pollinated species, indicating that severe habitat fragmentation may lead to pollen limitation and limited gene flow. In comparison with results of previous meta-analyses on mainly herbaceous species, we found trees and shrubs were as likely to have negative genetic responses to habitat fragmentation as herbaceous species. We also found that the genetic variation in offspring was generally less than that of adult trees, which is evidence of a genetic extinction debt and probably reflects the genetic diversity of the historical, less-fragmented landscape.     

Decoupling fragmentation from habitat loss for spiders in patchy agricultural landscapes

Habitat loss reduces species diversity, but the effect of habitat fragmentation on number of species is less clear because fragmentation generally accompanies loss of habitat. We compared four methods that aim to decouple the effects of fragmentation from the effects of habitat loss. Two methods are based on species-area relations, one on Fisher's alpha index of diversity, and one on plots of cumulative number of species detected against cumulative area sampled. We used these methods to analyze the species diversity of spiders in 2, 3.2 × 4 km agricultural landscapes in Southern Judea Lowlands, Israel. Spider diversity increased as fragmentation increased with all four methods, probably not because of the additive within-patch processes, such as edge effect and heterogeneity. The positive relation between fragmentation and species diversity might reflect that most species can disperse through the fields during the wheat-growing season. We suggest that if a given area was designated for the conservation of spiders in Southern Judea Lowlands, Israel, a set of several small patches may maximize species diversity over time.