Effective removal of antibiotic resistance genes and potential links with archaeal communities during vacuum-type composting and positive-pressure composting

As a major reservoir of antibiotics, animal manure contributes a lot to the augmented environmental pressure of antibiotic resistance genes (ARGs). This might be the first study to explore the effects of different ventilation types on the control of ARGs and to identify the relationships between archaeal communities and ARGs during the composting of dairy manure. Several ARGs were quantified via Real-time qPCR and microbial communities including bacteria and archaea were analyzed by High-throughput sequencing during vacuum-type composting (VTC) and positive-pressure composting (PPC). The total detected ARGs and class I integrase gene (intI1) under VTC were significantly lower than that under PPC during each stage of the composting (p < 0.001). The relative abundance of potential human pathogenic bacteria (HPB) which were identified based on sequencing information and correlation analysis decreased by 74.6% and 91.4% at the end of PPC and VTC, respectively. The composition of archaeal communities indicated that methane-producing archaea including Methanobrevibacter, Methanocorpusculum and Methanosphaera were dominant throughout the composting. Redundancy analysis suggested that Methanobrevibacter and Methanocorpusculum were positively correlated with all of the detected ARGs. Network analysis determined that the possible hosts of ARGs were different under VTC and PPC, and provided new sights about potential links between archaea and ARGs. Our results showed better performance of VTC in reducing ARGs and potential HPB and demonstrated that some archaea could also be influential hosts of ARGs, and caution the risks of archaea carrying ARGs.     

The impact of off-road vehicles on a desert ecosystem

The effects of operating a 4-wheel drive truck in a 9-ha area of the Mojave Desert were evaluated. A truck was driven over the same 0.9-km track 21 times between November 1973 and May 1974. The vehicle was also driven randomly around the area (1.3 to 3.4 km) 17 times between December 1973 and May 1974.Spring densities of annual plants in ruts of the regular track (8/m²) were less than those in control areas (46–112/m²), but densities in randomly driven plots (39/m²) did not differ significantly from controls. Severity of damage to shrubs was directly related to intensity of driving in the area. About 58% of shrubs growing in the regular track sustained estimated damage ranging from 81 to 100%. In randomly driven areas only 6% of shrubs were damaged to this extent, while about 61 % sustained damage from 0 to 20%.Numbers and kinds of rodents in control and driven areas were similar before and after the experiment. More young rodents were trapped in the experimental plot than in the control area during July 1974, and this may have been promoted by basal sprouting of new growth by damaged shrubs. Estimates of numbers of side-blotched lizards indicated similar densities before, during, and after the experiment. Counts of whiptail lizards in control and experimental areas were the same after the experiment, but counts of gridiron-tailed lizards were much lower in the driven area.     

城市化进程中环境风险评价的一些问题探讨

21世纪城市化过程改变了原来的生态系统 ,存在着潜在的风险。特别是近年来的多种环境风险灾害事故的发生已引起了各国和国际组织的普遍关注。我国“十六大”提出加快城镇化进程 ,是全面建设小康社会的重要内容。笔者结合目前环境风险评价的发展 ,将环境风险评价划分为非突发性风险评价和突发性风险评价两大类 ,对两类风险评价的概念、内容进行了分析阐述 ,探讨了有关两大类环境风险评价以及环境风险评价与安全评价的区别、环境风险评价评估标准以及在加强城市生态环境建设重建中开展环境风险评价的重要意义     

人误屏障分析技术

在复杂工业系统中,屏障是预防与减少人误的有效方法,一旦屏障失效,事故就有可能发生。笔者从屏障的概念与屏障分析入手,分析了实体屏障和管理屏障两类基本的屏障,介绍了屏障分析的6个步骤即辨识危险和目标、辨识屏障、评估屏障是否失效、弄清原因、评估与决定、制定方案及其分析案例,进行创建和维持屏障的方案分析,建立纠正行动计划的屏障方案,指出有效使用屏障分析技术来减少人误的几个场合以及屏障分析的局限性。     

Establishing a Context for River Rehabilitation, North Fork Gunnison River, Colorado

Initial river rehabilitation efforts along the North Fork Gunnison River in Colorado focused on the use of in-stream structures and channel stabilization to create a single-thread channel with pools along a braided river. These efforts were based on the assumption that the river’s braided planform results primarily from land use during the past century. In order to establish a context for further rehabilitation, we evaluated the possibility that the river might be braided as a result of processes independent of land use. We estimated volume, grain-size distribution, and lithology of sediment sources along the river corridor and evaluated the planform stability of the river during the past century using historical sources, aerial photographs covering 1939–1997, and comparison of bankfull discharge and gradient in the study area to values published for braided and meandering rivers. Our results indicate that the North Fork Gunnison River has been primarily braided in its lower reaches during the past few hundred years, although the channel planform tends toward a single-thread channel during decades of lower precipitation and discharge. Although land use is not the primary cause of braiding along the North Fork Gunnison River, it has decreased channel stability, and rehabilitation efforts should be designed to reduce these effects. Our results illustrate the importance of planning river rehabilitation measures within a historical context that accounts for both catchment-scale and reach-scale controls on channel processes and planform.     

A Disturbance Index for Karst Environments

Karst environments, unique from other environments, require their own disturbance index. Karst resources are increasingly disturbed by a variety of processes related to social, physical, and economic factors. Recent studies have begun to qualify and quantify these disturbances, yet their focus has been limited to one or two factors such as biotic, geomorphic, or economic impacts. A more holistic approach, addressing economic, scientific, and cultural factors, is needed, to effectively assess the threats to karst areas. Currently, there is no efficient method to measure, compare, and contrast the disturbance of karst environments. We propose a hierarchal and standardized environmental disturbance index as a tool to measure regional impacts and highlight the areas of the karst system that require more protection or study. Addressed categories of disturbance include cultural, biotic, atmospheric, hydrological, and geomorphologic impacts.     

1990～2003年中国民航152起小于间隔飞行事件的分类统计研究

小于间隔飞行事件是双机空中相撞事故的潜在威胁 ,对此类事件进行人的因素的分类统计分析有助于寻找错误原因和规律。笔者以 15 2起小于间隔飞行事件为数据源 ,根据Reason模型和HFACS系统进行分类 ,统计了各个因素所占的百分比和部分因素的相关程度。结果表明 ,小于间隔事件与生物节律的关系并不明显而与交通流量密切相关 ;机组不安全行为与管制员未能有效实施监控职能密切相关 ;决策错误、操作错误和知觉错误的主要表现形式分别为 :混淆指令、调错高度窗、听错指令和记错 /忘记管制员指令以及未理解管制员指令 ;不良的机组资源管理是导致小于间隔最主要的机组因素 ,主要表现形式为机组成员之间的配合不好、未有效实施交互监视和交互检查 ;“高度指令”和“相对活动高度”提示的语序问题是一个值得进一步研究的课题。     

行为矫正法在建筑火灾安全中的应用研究

随着建筑物防火性能化的发展以及人行为机理的复杂性 ,要求应用更多的学科研究建筑物火灾中人的行为与安全疏散理论。行为矫正学是一门基于过去经验与实验研究的学科 ,笔者在阐述其基本原理和特点的基础上 ,提出了在灾害事故中应用此方法的模式 ,然后结合高层建筑物火灾疏散的特点 ,对高层居民建筑物发生火灾时 ,如何矫正人的一些不正确F行为和提高火灾安全进行了探讨。分析了矫正模式的功能和干预的措施。     

核电站事故前人因可靠性分析方法

人因可靠性分析 (HRA)已成为概率安全分析 (PSA)必不可少的内容 ,事故前人因事件可靠性分析对有效预防维修、调校工作中的人因失误有着重要作用 ,是人因可靠性分析的重要组成部分 ,对PSA最终计算结果有重要影响。笔者结合核电站人因可靠性分析的实际需求 ,运用了以THERP为主的人因失误概率评价方法 ,创建了事故前人因事件分析的基本程序、方法及分析文档模式 ,表述了程序化的事故前人因事件分析模式 ,为我国核电站事故前人因可靠性分析提供了完整和有效的分析方法 ,并有效用于秦山核电站的PSA。     

核电厂人因及组织行政管理安全审查体系

定期安全审查 (PSR)是国际原子能机构 (IAEA)近年推广的一种新的核电厂安全审查方式 ,它强调系统性、全面性和关键性。人因安全因素 (HF)、组织机构和行政管理安全因素 (OA)是PSR的重要组成部分 ,也是PSR中审查难度较大的部分之一。其难点主要在于如何用有限的评审指标去刻画出最能表征人因、OA对核电厂安全运行最具影响的特征因子 ,建立起科学的、系统化的审查体系 ,且该体系还需具有较强的可操作性。基于上述认识 ,笔者建立了核电厂人因及组织行政管理安全审查体系 ,它包含安全目标与方针、人员配备与资格、组织机构与管理、配置控制、培训、职业健康、运行经验反馈、质量保证、人 -机接口、遵章守法等 10类 19个要素。同时介绍了其评审指标、审查内容、审查方法和程序等。该体系已应用于秦山核电厂。