Dynamic changes in microbial activity and community structure during biodegradation of petroleum compounds： A laboratory experiment

With 110-d incubation experiment in laboratory,the responses of microbial quantity,soil enzymatic activity,and bacterial community structure to different amounts of diesel fuel amendments were studied to reveal whether certain biological and biochemical characteristics could serve as reliable indicators of petroleum hydrocarbon contamination in meadow-brown soil,and use these indicators to evaluate the actual ecological impacts of 50-year petroleum-refining wastewater irrigation on soil function in Sbenfu irrigation area.Results showed that amendments of≤1000 mg/kg diesel fuel stimulated the growth of aerobic beterotrophic bacteria,and increased the activity of soil dehydrogenase,hydrogenperoxidase,polypbenol oxidase and substrate-induced respiration.Soil bacterial diversity decreased slightly during the first 15 d of incubation and recovered to the control level on day 30.The significant decrease of the colony forming units of soil actinomyces and filamentous fungi can be taken as the sensitive biological indicators of petroleum contamination when soil was amended with≥5000 mg/kg diesel fuel.The sharp decrease in urease activity was recommended as the most sensitive biochemical indicator of heavy diesel fuel contamination.The shifts in community structure to a community documented by Sphingomonadaceae withinα-subgroup of Proteobacteria could be served as a sensitive and precise indicator of diesel fuel contamination.Based on the results described in this paper,the soil function in Shenfu irrigation area was disturbed to some extent.     

河北省38°N生态样带生态系统服务功能时空变化

河北省38°N生态样带是一条由太行山区-山前平原区-低平原区-滨海平原区组成的典型生态样带。论文引进区域修正系数和环境成本系数对前人的生态系统服务功能价值评估模型进行改进,并对该生态样带土地利用变化驱动下的生态系统服务功能时空变化进行了研究。结果表明:1990-2008年,该生态样带的生态系统服务功能价值总量由334.83×10⁸元增至360.13×10⁸元,但食物生产功能价值持续减少,累计减少了4.67%。太行山区的生态系统服务功能单位面积价值为西高东低,主要由林地和草地提供;山前平原区和低平原区的生态系统服务功能单位面积价值较低且分布均匀,主要由农田提供;滨海平原区的生态系统服务功能单位面积价值东部明显高于中西部,主要由水体和湿地提供。     

花江小流域石漠化过程中的土壤有机碳氮的变化

以花江峡谷区1.2 km2小流域为研究对象,通过设置不同喀斯特石漠化强度的样地,研究不同等级石漠化样地的土壤有机碳、全氮含量在石漠化过程中的变化。结果表明,喀斯特生境中土壤具有高度异质性,人为干扰方式对土壤有机碳、全氮含量变异性的影响很大;樵采石漠化样地小生境土壤有机碳、全氮含量维持在较高水平,开垦石漠化样地小生境土壤有机碳、全氮含量较低;随着石漠化程度的加剧,樵采和开垦系列样地土壤有机碳、全氮含量呈现不断降低的趋势,这在一定程度上体现了石漠化过程的土壤退化本质。小流域内石漠化成因类型的划分对揭示石漠化过程中的土壤退化是必须的。     

Imputing Unmeasured Explanatory Variables in Environmental Epidemiology With Application to Health Impact Analysis of Air Pollution

This paper presents the results of a reconsideration of earlier work that finds an association between daily hospital admissions for respiratory distress and daily concentrations of sulphate (lag 1) as well as daily maximum concentrations of ozone (lags 1 and 3). These associations are found even after clustering the data by hospital of admission and accounting for the effects of temperature. We use an adaptation of their generalized estimating equation technique for clustered data, that daily data being for southern Ontario summers from 1983 to 1988. Like them, we adjust for daily maximum temperatures. However, unlike the earlier work returned to ours includes daily average humidity as a potential explanatory variable in our model. Our analysis also differs from theirs in that we cluster the data by census subdivision to reduce the risk of confounding pollutant levels with population size within regions. Moreover, we log-transform the explanatory variables and then high-pass filter the resulting data. We also deviate from the earlier analysis by taking account of measurement error incurred in using surrogate measures of the explanatory variables. To do so we use new methodology designed for our study but of potential value in other applications. That methodology requires a spatial predictive distribution for the unmeasured explanatory variables. Each day about 700 missing measurements for each of these variables can then be imputed over the geographical domain of the study. With these imputations we get a measure of imputation error through the covariance of the predictive distribution. Along with the predictive distribution we require an impact model to link-up with the predictive distribution. We describe that model and show how it uses the imputed measurements of the missing values of the explanatory variables. We also show how through that model, uncertainty about these values is reflected in our analysis and in commensurate uncertainties in the inferences made. Apart from its substantive objectives, our analysis serves to test the new methods with the earlier results serving as a foil. The reassuring qualitative agreement between our findings and the earlier results seems encouraging.     

地表水中典型磺胺类抗生素的自然衰减

近年来,磺胺类抗生素因大量使用,在河流等地表水中广泛检出,其环境行为及生态危害,成为备受关注的环境问题.本文以10种常见磺胺类抗生素为研究对象,通过微宇宙实验,模拟其在河流表层水中的自然衰减规律,同时模拟直接光降解、间接光降解、水解、细菌降解和微生物降解等多种条件,以阐明不同环境因素对磺胺类抗生素自然衰减的作用机制.结...     

基于ISM和ANP的水库水华发生影响因素分析

为提高水库水华发生预警能力,从水华形成机理着手,引入营养盐条件、水动力条件、光热条件和浮游植物生长状况,建立水库水华发生影响因素模型.首先,基于文献研究,建立水库水华发生影响因素体系,共包含10个指标;其次,利用解释结构模型(ISM)建立水库水华发生影响因素递阶结构模型;最后采用网络层次分析法(ANP)构建权重模型,并...     

基于CFD仿真的炮口制退器性能影响因素研究

目的 在降低火炮后坐力的同时,保证炮手区域超压和温度符合要求。方法 利用流体仿真软件进行炮口流场的数值模拟,对制退器性能影响因素进行仿真分析。根据分析结果,得到改进后的制退器模型,并进行仿真和试验对比。结果 加装侧孔外反射挡板和侧孔倾斜对制退器性能的影响较大,并随角度的变化而变化,加装吹孔能有效降低炮后超压和温度。改进后,制退器的效率提升8.33%,炮后超压值平均降低44.10 kPa,炮后温度值平均降低358.28 K。结论 改进后的制退器具有更高的制退效率以及较低的炮后超压值和温度值。     

地铁乘客火灾应激反应过程模型构建与分析

为提高地铁乘客的火灾应对能力,基于应激反应模型,构建地铁火灾应激反应过程理论模型;收集357份有效问卷数据,采用因子分析和结构方程模型(SEM),探讨个体特性、特定情境、认知评价、社会支持、应对方式和应对结果6个变量及变量各维度之间的相互影响关系.研究结果表明:个体特性可以正向调节心理反应结果,特定情境变量可以反向调节...     

Assessing the effects of land use changes on soil sensitivity to erosion in a highland ecosystem of semi-arid Turkey

There has been increasing concern in highlands of semiarid Turkey that conversion of these systems results in excessive soil erosion, ecosystem degradation, and loss of sustainable resources. An increasing rate of land use/cover changes especially in semiarid mountainous areas has resulted in important effects on physical and ecological processes, causing many regions to undergo accelerated environmental degradation in terms of soil erosion, mass movement and reservoir sedimentation. This paper, therefore, explores the impact of land use changes on land degradation in a linkage to the soil erodibility, RUSLE-K, in Cankiri–Indagi Mountain Pass, Turkey. The characterization of soil erodibility in this ecosystem is important from the standpoint of conserving fragile ecosystems and planning management practices. Five adjacent land uses (cropland, grassland, woodland, plantation, and recreational land) were selected for this research. Analysis of variance showed that soil properties and RUSLE-K statistically changed with land use changes and soils of the recreational land and cropland were more sensitive to water erosion than those of the woodland, grassland, and plantation. This was mainly due to the significant decreases in soil organic matter (SOM) and hydraulic conductivity (HC) in those lands. Additionally, soil samples randomly collected from the depths of 0–10 cm (D ₁) and 10–20 cm (D ₂) with irregular intervals in an area of 1,200 by 4,200 m sufficiently characterized not only the spatial distribution of soil organic matter (SOM), hydraulic conductivity (HC), clay (C), silt (Si), sand (S) and silt plus very fine sand (Si + VFS) but also the spatial distribution of RUSLE-K as an algebraically estimate of these parameters together with field assessment of soil structure to assess the dynamic relationships between soil properties and land use types. In this study, in order to perform the spatial analyses, the mean sampling intervals were 43, 50, 64, 78, 85 m for woodland, plantation, grassland, recreation, and cropland with the sample numbers of 56, 79, 72, 13, and 69, respectively, resulting in an average interval of 64 m for whole study area. Although nugget effect and nugget effect–sill ratio gave an idea about the sampling design adequacy, the better results are undoubtedly likely by both equi-probable spatial sampling and random sampling representative of all land uses.     

中国对外直接投资影响母国环境的理论机理与实证研究

经济全球化背景下,中国工业化进程深度融入全球价值链分工体系,在以资源能源消耗与要素投入增加为特征的粗放型经济增长模式下,国际贸易与国际投资在带动中国经济迅速发展的同时,也不可避免地影响国内的资源环境形势。基于此,本文以中国为研究对象,探究对外直接投资对母国环境的影响及其作用机制,对于“一带一路”战略背景下中国改善生态环境质量、推动经济绿色发展,具有重要的现实意义。本文首先从经济规模扩张、产业结构转型以及技术水平增进等三个视角,构建起对外直接投资影响母国环境的理论框架,并提出相应研究假说。随后,基于中介效应法,构建动态面板模型,在核算各省综合污染指数基础上,结合省级面板数据与系统GMM估计方法,实证探究对外直接投资对母国环境的基本影响,并对其作用机制进行了检验、识别与分析。多个角度开展的稳健性检验依然表明实证结果是稳健的。研究结论如下:一是对外直接投资通过推动母国经济规模扩张,导致其污染物排放增加;二是对外直接投资通过促进母国产业结构朝向服务化转型,有利于减少其污染物排放;三是对外直接投资通过引致反向技术溢出效应,有利于母国污染物排放减少;四是综合来看,当前中国推动对外直接投资,有利于减少母国污染物排放。最后,本文从优化国际投资结构、强化技术领域国际合作等方面提出促进中国环境治理的政策建议。