龙江县景星镇十年退耕还林生态影响分析

退耕还林工程是我国生态环境保护建设的一项重大措施,景星镇从2002年实施退耕还林工程以来,森林覆盖率显著提高,生态环境明显变化。主要表现在:水土流失得到有效控制、土壤有机质提高,土壤肥力得以修复;林地涵养水源、固碳释氧的功能得到发挥,生境改善,生物多样性恢复。     

基于环境恢复的环境污染损害责任与建立

环境本身损害的责任缺失是我国环境污染管理中亟待解决的突出问题。文章从社会经济系统与其支撑环境间作用关系过程链的三个响应环节出发,分析了建立环境本身损害责任机制的作用、意义及环境本身损害赔偿的内涵与构成。提出了围绕突发性污染排放问题,以恢复环境为目标,衔接我国环境应急管理系统实施环境本身损害责任的构架。结合突发性污染排放建立环境损害的恢复责任,对推进环境污染损害管理和深化污染事故应急处置具有重要支持作用。     

基于降水化学的北京城乡大气污染物差异探析

降雨化学成份的变化间接反映大气污染特征,是研究大气环境及沉降物影响的重要途径.本文比较了2013与2014年雨季北京市区到郊县延庆4个样点上降雨成份的时空差异,并结合PMF模型分析了各主要离子的可能来源.结果表明,4个样点降雨pH中值分别为6.52、6.57、6.60、6.52,从市区到远郊略有增加.各离子浓度都是春秋季高,夏季低.降雨中各离子的雨量加权平均浓度(VWM)表现为:Ca~(2+)、NH_4~+、SO_4~(2-)较高,分别在100~400μeq·L~(-1)、100~350μeq·L~(-1)、150~500μeq·L~(-1)之间,Mg~(2+)、Na~+和NO_3~-分别在0~150μeq·L~(-1)、0~250μeq·L~(-1)、0~150μeq·L~(-1)之间,K~+和Cl~-较低,分别在0~45μeq·L~(-1)、0~90μeq·L~(-1)之间.NH_4~+、Mg~(2+)的VWM从市区到郊区递减,K~+、SO_4~(2-)-S、Na~+、NO_3~呈近郊区略有增大,远郊区全部减小的趋势.SO_4~(2-)是主要的致酸离子,Ca~(2+)、NH_4~+和Mg~(2+)对雨水中酸根离子的中和因子平均值分别为0.5、0.4和0.1.市区BNU点SO_4~(2-)-S(以S计)与Ca~(2+)的沉降量分别为55.66 kg·hm~(-2)·a~(-1)和24.10 kg·hm~(-2)·a~(-1),在远郊YQ点为26.03 kg·hm~(-2)·a~(-1)和10.84kg·hm~(-2)·a~(-1).NH_4~+-N与NO_3~-N的沉降量在4点的变化范围为7.27~14.05 kg·hm~(-2)·a~(-1)及2.50~5.07 kg·hm~(-2)·a~(-1).Mg~(2+)和Cl~-从市区到远郊分别在1.32~4.48 kg·hm~(-2)·a~(-1)及3.67~6.10 kg·hm~(-2)·a~(-1)之间变化.所有离子以湿沉降为主,沉降量与相应的降雨量变化较为一致.根据PMF模拟结果,4点的地面扬尘和建筑源污染均较高,市中心尾气污染最严重,近市区二次源污染严重,近郊区氮污染严重,远郊区受养殖场、垃圾源等的NH_3排放影响较大.     

一株抗铬细菌的分离鉴定及其还原特性研究

拟通过筛选出高效还原Cr(Ⅵ)的菌株来修复铬污染土壤,从重庆废弃化工厂铬污染土壤中分离得到一株高效还原菌株,对该菌进行形态和生理生化特征研究,并结合分子生物学进行测序分析,同时对该菌在不同条件下还原Cr(Ⅵ)的能力进行检测,探讨了pH值、接种量、初始Cr(Ⅵ)质量浓度及温度对Cr(Ⅵ)还原的影响.结果表明,该菌株为革兰氏阳性杆菌,命名为NO.1.经形态和生理生化特征及16S rDNA序列比对分析,鉴定为蜡样芽孢杆菌(Bacillus cereus)(相似度为99％).该菌株具有较强的还原Cr(Ⅵ)的能力,在pH=8.0、接种量50％(体积分数)及30℃条件下,100 mg/L的Cr(Ⅵ)在处理3d后可基本被还原.研究表明,该细菌有望用于铬污染土壤的修复.     

基于AHP-SLIM的航空器维修人误概率确定

人误是造成民用航空维修差错的主要因素。由于缺少实际的数据,对航空维修行业人为失误发生的规律进行研究是必要的,但是规律研究主要依赖于该领域专家的判断,很难确保一致性。为了克服这个困难得到更加准确的评估,本文将层次分析法同成功似然函数结合起来估计造成飞机/发动机/附件损坏的人误概率。该方法确定了航空器维修人员的安全态度、知识和技能、计划和监管、信息沟通等因素,对人误的影响程度以及飞机/发动机/附件损坏中常见人误的发生概率。计算结果表明,操作/试验时最容易发生飞机/发动机/附件损坏,并且提出加强组织和监管、严格按章办事等解决措施。     

不同菜地土壤的铁氨氧化脱氮过程探究

采集了不同菜地的土壤，分析其理化性质.采用同位素示踪技术测定了铁氨氧化、反硝化和厌氧氨氧化的速率，运用Miseq高通量测序技术探究了菜地土壤的群落组成.结果表明，铁氨氧化速率在种植蔬菜的土壤显著高于裸地的土壤，并且铁氨氧化速率与土壤Fe（III）（r = 0.736， P < 0.05）和总有机碳（r = 0.575， P < 0.05）均有显著的正相关.另外，在不同菜地中5种主要的铁还原菌（芽孢杆菌属，假单胞菌属，嗜酸菌属，脂环酸芽孢杆菌属，梭状芽胞杆菌属）被检测到，并且铁还原菌的相对丰度在种植蔬菜的土壤（1.38%~2.19%）比在裸地的土壤（0.75%）高.在脱氮贡献方面铁氨氧化， 反硝化和厌氧氨氧化分别贡献了7.3%~12.4%， 53.1%~72.3%和18.9%~36.4%的氮气产生，说明铁氨氧化是菜地中重要的微生物脱氮路径.     

Demographic Characteristics of Extinction in a Small, Insular Population of House Sparrows in Northern Norway

Abstract:  In conservation ecology there is an urgent need for indicators that can be used to predict the risk of extinction of populations. Identifying extinction-prone populations has been difficult because few data sets on the demographic characteristics of the final stage to extinction are available and because of problems in separating out stochastic effects from changes in the expected dynamics. We documented the demographic changes that occurred during the period prior to extinction of a small island population of House Sparrows ( Passer domesticus ) after the end of permanent human settlement. A mark-recapture analysis revealed that this decline to extinction was mainly due to increased mortality after closure of the last farm that resulted in a negative long-term-specific growth rate. No change occurred in either the structural composition (breeding sex ratio and age distribution) of the population or in female recruitment. No male, however, recruits were produced on the island after the farm closure. Based on a simple, stochastic, density-dependent model we constructed a population prediction interval (PPI) to estimate the time to extinction. The 95% PPI slightly overestimated the time to extinction with large uncertainty in predictions, especially due to the influence of demographic stochasticity and parameter drift. Our results strongly emphasize the importance of access to data on temporal variation that can be used to parameterize simple population models that allow estimation of critical parameters for credible prediction of time to extinction.     

Evaluation of municipal solid waste composting kinetics

Most modern municipal solid waste (MSW) composting operations have emphasized the enhancement of decomposition of the organic fraction of the waste to comply with strict environmental regulations. This can be achieved once the composting process kinetics are well understood. This study examined process kinetics through experimentation with bench-scale reactors under controlled composting conditions to show the interdependence between biological, chemical and physical factors during composting of MSW. The effects of temperature, moisture content, waste particle size and carbon to nitrogen (C/N) ratio on process kinetics were evaluated. The results obtained revealed that these factors should be carefully controlled in order to achieve optimum process performance. It has been found that the organic matter degradation during composting follows a first-order kinetic model.     

宇宙线辐射对人类健康的影响

介绍了宇宙线辐射对人类在不同生活环境和活动空间中所致的剂呈，估计了航空机组人员受到宇线照射潜在的危险性，并作出了卫生学评价。     

A review on political factors influencing public support for urban environmental policy

Environmental quality is important to urban residents’ physical, social and psychological well-being. Governments have been formulating and implementing policies to mitigate environmental deterioration in cities. To effectively implement policies and achieve policy goals, gaining sufficient public support is an essential prerequisite; the policies would be in ruins and the government may also suffer from setbacks in other policy areas in the absence of public support. Therefore, to understand what contributes to public support is a crucial task for policymakers. Though current literature on socio-demographic and attitudinal/psychological factors provides fruitful accounts for policy support, a comprehensive examination of political determinants has yet to be established. In response to this, this review paper explores political factors that influence level of policy support based on existing literature. An integrated framework is proposed to explain policy support for urban environmental policy. This paper also discusses the possible directions of future research.