Benchmark Dose Assessment for Coke Oven Emissions-Induced Mitochondrial DNA Copy Number Damage Effects

Objective The study aimed to estimate the benchmark dose(BMD)of coke oven emissions(COEs)exposure based on mitochondrial damage with the mitochondrial DNA copy number(mtDNAcn)as a biomarker.Methods A total of 782 subjects were recruited,including 238 controls and 544 exposed workers.The mtDNAcn of peripheral leukocytes was detected through the real-time fluorescence-based quantitative polymerase chain reaction.Three BMD approaches were used to calculate the BMD of COEs exposure based on the mitochondrial damage and its 95%confidence lower limit(BMDL).Results The mtDNAcn of the exposure group was lower than that of the control group(0.60±0.29 vs.1.03±0.31;P<0.001).A dose-response relationship was shown between the mtDNAcn damage and COEs.Using the Benchmark Dose Software,the occupational exposure limits(OELs)for COEs exposure in males was 0.00190 mg/m^(3).The OELs for COEs exposure using the BBMD were 0.00170 mg/m^(3)for the total population,0.00158 mg/m^(3)for males,and 0.00174 mg/m^(3)for females.In possible risk obtained from animal studies(PROAST),the OELs of the total population,males,and females were 0.00184,0.00178,and 0.00192 mg/m^(3),respectively.Conclusion Based on our conservative estimate,the BMDL of mitochondrial damage caused by COEs is0.002 mg/m^(3).This value will provide a benchmark for determining possible OELs.

Plasma Wall Potentials with Secondary Electron Emissions up to the Stable Space-Charge-Limited Condition

Numerical solutions to floating plasma potentials for walls emitting secondary elec- trons are obtained for various surface materials. The calculations are made with plasma moment equations and the secondary electron emission coefficients, which were determined from recent laboratory experiments. The results estimate the wall potentials up to the physical conditions that allow stable plasma sheaths under the space-charge-limited condition. The materials often used in the laboratory, such as aluminum, silicon, boron, molybdenum, silicon dioxide, and alumina, are considered. The minimum wall potential before the onset of space-charge-limited emission is determined by the electron temperatures at which the effective secondary electron emission coefficient integrated over the velocity distributions is about 0.62. The corresponding potential is given by -eφ0 ,- 1.87kBT. The condition for space-charge-limited emission is newly found by numerically searching for all the stable sheaths. The new condition is -eφ0 - 0.95kBT, and this predicts a wall potential that is less negative than the previously found one. Calculation of the power dissipated to the wall for hydrogen plasmas shows that there is a large difference in terms of power dissipation among the considered materials in the temperature range 20-50 eV.

China may adopt emission limit

According to the news from China Daily, China is likely to agree to a quantified target to limit its greenhouse gas emissions after 2020. But this depends on the outcome of climate change negotiations and China’s level of development by that time. This is the first time

Correlation between carbon emissions,fuel consumption of vehicles and speed limit on expressway

This paper aimed to investigate the correlation between carbon emissions,fuel consumption,and speed limit.A theoretical model was derived based on the energy conservation law,which expresses the relationship between vehicle's fuel consumption and speed.Subsequently,a total of 40 sets of fuel consumption data were collected through field tests to verify the accuracy of the theoretical model at different speeds and different road longitudinal slope combinations.The fuel consumption was then converted to carbon emissions according to the carbon emission factors specified by Intergovernmental Panel on Climate Change(IPCC).In the field experiment,two types of cars and trucks,which are most common on the expressways in China,were selected.Finally,the travel speed under different posted speed limits was obtained through the previously established model,and the carbon emission changes of different vehicle types at different limited speeds are calculated.The results show that the speed limit has a significant impact on fuel consumption and carbon emissions.When the speed limit increased from 80 to 120 km/h,average vehicle speeds increased about 21%-27%,and fuel consumption and carbon emissions increased from approximately 33%-38%.Another interesting result was that the vehicle's fuel consumption and carbon emissions are only affected by speed.The results of the study explore the effect of speed limits on carbon emissions and provide evidence for road managers to set reasonable speed limits.

Near-Zero Air Pollutant Emission Technologies and Applications for Clean Coal-Fired Power

Coal is the dominant energy source in China,and coal-fired power accounts for about half of coal consumption.However,air pollutant emissions from coal-fired power plants cause severe ecological and environmental problems.This paper focuses on near-zero emission technologies and applications for clean coal-fired power.The long-term operation states of near-zero emission units were evaluated,and synergistic and special mercury(Hg)control technologies were researched.The results show that the principle technical route of near-zero emission,which was applied to 101 of China’s coal-fired units,has good adaptability to coal properties.The emission concentrations of particulate matter(PM),SO2,and NOx were below the emission limits of gas-fired power plants and the compliance rates of the hourly average emission concentrations reaching near-zero emission in long-term operation exceeded 99%.With the application of near-zero emission technologies,the generating costs increased by about 0.01 CNY∙(kW∙h)-1.However,the total emissions of air pollutants decreased by about 90%,resulting in effective improvement of the ambient air quality.Furthermore,while the Hg emission concentrations of the near-zero emission units ranged from 0.51 to 2.89μg∙m^-3,after the modified fly ash(MFA)special Hg removal system was applied,Hg emission concentration reached as low as 0.29μg∙m^-3.The operating cost of this system was only 10%-15%of the cost of mainstream Hg removal technology using activated carbon injection.Based on experimental studies carried out in a 50000 m^3∙h^-1 coal-fired flue gas pollutant control pilot platform,the interaction relationships of multi-pollutant removal were obtained and solutions were developed for emissions reaching different limits.A combined demonstration application for clean coal-fired power,with the new“1123”eco-friendly emission limits of 1,10,20 mg∙m^-3,and 3μg∙m^-3,respectively,for PM,SO2,NOx,and Hg from near-zero emission coal-fired power were put forward and realized,providing engineering and technical support for the national enhanced pollution emission standards.

An iterative virtual projection method to improve the reconstruction performance for ill-posed emission tomographic problems

In order to improve the reconstruction performance for ill-posed emission tomographic problems with limited projections, a generalized interpolation method is proposed in this paper, in which the virtual lines of projection are fabricated from, but not linearly dependent on, the measured projections. The method is called the virtual projection（VP） method.Also, an iterative correction method for the integral lengths is proposed to reduce the error brought about by the virtual lines of projection. The combination of the two methods is called the iterative virtual projection（IVP） method. Based on a scheme of equilateral triangle plane meshes and a six asymmetrically arranged detection system, numerical simulations and experimental verification are conducted. Simulation results obtained by using a non-negative linear least squares method,without any other constraints or regularization, demonstrate that the VP method can gradually reduce the reconstruction error and converges to the desired one by fabricating additional effective projections. When the mean square deviation of normal error superimposed on the simulated measured projections is smaller than 0.03, i.e., the signal-to-noise ratio（SNR）for the measured projections is higher than 30.4, the IVP method can further reduce the reconstruction error reached by the VP method apparently. In addition, as the regularization matrix in the Tikhonov regularization method is updated by an iterative correction process similar to the IVP method presented in this paper, or the Tikhonov regularization method is used in the IVP method, good improvement is achieved.

Enhanced field emission characteristics of thin-Au-coated nano-sheet carbon films

This paper reports that the nano-sheet carbon films （NSCFs） were fabricated on Si wafer chips with hydrogen- methane gas mixture by means of quartz-tube-type microwave plasma chemical vapour deposition （MWPCVD）. In order to further improve the field emission （FE） characteristics, a 5-nm Au film was prepared on the samples by using electron beam evaporation. The FE properties were obviously improved due to depositing Au thin film on NSCFs. The FE current density at a macroscopic electric field, E, of 9 V/μm was increased from 12.4 mA/cm2 to 27.2 mA/cm2 and the threshold field was decreased from 2.6 V/μm to 2.0 V/μm for Au-coated carbon films. A modified F-N model considering statistic effects of FE tip structures in the low E region and a space-chavge-limited-current effect in the high E region were applied successfully to explain the FE data of the Au-coated NSCF.

Understanding Human Development Potentials and Demands for Greenhouse Gas Emissions:with Empirical Analysis using time series and cross-sectional data

Based on an investigation of the meaning of development, the neo-classical economic approach to development, and the post-welfarist theory of development, this paper proposes a conceptual framework for understanding human development potentials, while undertaking empirical analysis using cross-sectional and time series data on human development. Human development is associated with basic necessities for subsistence, the quality of life, and political and civil rights, in addition to income indicators. Our analysis suggests that the concept of human development potentials has two dimensions: the rights of development and limits to human development. Both are largely ignored in the neoclassical theory of development. However, human development is not unbounded, which approaches to a relatively fixed constant at given economic, technological and institutional conditions. This conceptual understanding is supported by results from the empirical examination of the relationships between demands for carbon

Research on the field emission mechanism of nano-structured carbon film

The field emission （FE） characteristics of nano-structured carbon films （NSCFs） are investigated. The saturation behaviour of the field emission current density found at high electric field E cannot be reasonably explained by the traditional Fowler-Nordheim （F-N） theory. A three-region E model and the curve-fitting method are utilized for discussing the FE characteristics of NSCFs. In the low, high, and middle E regions, the FE mechanism is reasonably explained by a modified F-N model, a corrected space-charge-limited-current （SCLC） model and the joint model of F N and SCLC mechanism, respectively. Moreover, the measured FE data accord well with the results from our corrected theoretical model.

YSZ基极限电流型NO_(x)传感器研究进展

随着汽车尾气排放标准更加严格,NO_(x)传感器作为主要排放处理技术-选择性催化还原系统(SCR)的核心部件成为当下的研究热点。YSZ作为固体电解质的极限电流型传感器在监测精度和控制成本上有着显著作用。综述了近年极限电流型氧传感器和NO_(x)传感器的研究进展。介绍了传感器的历史发展、结构和工作机理。重点阐述了扩散层、电极层的材料选择和结构组成对传感器性能的影响。基于目前集成MEMS气体薄膜传感器的发展以及传感单元结构多腔耦合组合模型的不断完善,提出未来亟待解决的问题,预测可能的发展方向。

电子束发射诱发航天器充电的数值模拟研究

通过发射电子束测量空间地磁场是一种新的有效的地磁场高精度测量方法,但电子束发射对在轨航天器自身状态和安全存在影响。为了研究这一影响,从同步轨道充电机制出发,基于轨道限制机制和朗缪尔方程研究了航天器发射高能电子束时的诱发充电模型,推导了不同初始电位情况下束流发射的平衡电位公式,并编制程序研究了这一过程中粒子束电流、能量、光照等因素对航天器充电电位的影响,得到了航天器对外发射高能电子束时诱发航天器自身或平台的充电电位随时间变化规律,并通过部分解析解对比验证了模拟结果的正确性。

新型高炉煤气干法脱硫技术在衡钢的应用

高炉煤气总硫含量约100~200 mg/m^(3),燃烧后不能满足工业炉窑的环保排放限值要求。文章提出了一种在TRT后端设置羰基硫转化装置的新型高炉煤气干法脱硫技术,并在某钢铁公司应用。运行结果表明处理后的高炉煤气含硫量小于5 mg/m^(3),满足高炉煤气燃烧后直接达标排放的要求。

在用汽车污染物排放限值标准用气体标准物质现状及探讨

在用车污染物排放限值标准GB 18285-2018及GB 3847-2018已于2019年5月1日正式实施。相比旧版标准,修订后标准污染物种类增加,排放限值降低,对检测用气体标准物质的要求明显提高。本文针对该两项标准的修订内容,结合国内在用汽车污染物检测用气体标准物质现状,对标准所需气体标准物质进行了解读和探讨,对确保移动源污染排放检测量值的准确性与溯源性具有一定的指导意义。

从科层到发包:碳排放配额初始分配央地事权的规范配置

我国碳排放权交易体系进入全国碳市场与地方碳市场并存的“双轨制”运行阶段,碳排放配额初始分配的央地事权配置面临新的规范需求。当前碳配额初始分配的央地事权配置深受科层治理模式的影响,呈现横向事权集中与纵向事责下放的部门“垂直”主导;被悬置的地方政府与委重任的地方职能部门的横向“属地”虚置;碳配额分配中央委托事权与地方固有事权的交织形态。受“集权-分权”思维局限的科层事权配置加剧央地权界封闭、权能受限、权责错位的固有弊端,造成双轨结构下碳配额分配央地事权边界固化、层级管理下碳配额分配主体功能式微、目标考核下事权与事责分离导致的行动乏力。优化碳配额分配央地事权配置须遵循“控权-赋权”理念,实现央地权界由“中央主导-地方配合”向“地方实施-中央监督”的动态调整;以“有限发包-省级统管”实现央地权能的高效配置;以“共同但有区别”的合作治理与责任分工实现央地权责精准适配。未来应以“专章立法+权力清单”为载体,采取概括式与列举式相结合的立法模式,从形式法治到实质法治对央地碳配额分配事权展开体系化构建。

基于减污降碳和水质目标约束下的黄河干流兰州段城区污水处理厂出水排放限值研究

为科学合理地提出黄河干流兰州段城区污水处理厂出水排放限值,实施精准科学治污,持续改善黄河干流兰州段水环境质量,本文以兰州市城区四座有代表性的污水处理厂(西固、七里河安宁、盐场和雁儿湾污水处理厂)为研究对象,统计四座污水处理厂主要污染物排放浓度、中水回用率、主要污染物去除率及减排效果,分析四座污水处理厂入河排污对黄河干流兰州段水质的影响,梳理污水处理厂运行阶段的碳排放情况.结果表明:(1)兰州市城区四座污水处理厂中水回用率低,介于0.86%~4.66%之间.(2)四座污水处理厂主要污染物的去除率高于国内污水处理厂主要污染物去除率的平均水平,COD、NH_(3)-N年均减排量分别为114584.1、8234.6 t,减排效果明显.(3)在黄河枯水期上游来水水量小、水质接近或超出GB 3838-2002《地表水环境质量标准》Ⅱ类水质目标限值的条件下,叠加区间其他入河排污口的影响,兰州市城区四座污水处理厂均按照设计规模及设计出水水质排污会对下游河段水质造成影响.因此,不能一味地追求出水水质,盲目提标改造,要综合考虑污水处理厂运行过程中的碳排放,在满足受纳水体水质目标前提下,统筹考虑减污降碳.

碳排放限制的混杂最优闭环电网经济调度

针对电网经济调度效率低下等问题,提出了一种碳排放限制的混杂最优闭环电网调度算法。算法在考虑火力发电机组和多分布式发电聚合体组合调度的同时,以电网实际需求响应和碳排放限制作为约束条件,建立电网经济调度模型;并将经济调度问题转化为混杂系统的最优控制,从而建立电网经济调度与混杂系统最优控制序列的等价一致性;推导混杂系统获取满足贝尔曼方程的最优代价函数,借助神经网络逼近最优值获得最优闭环调度序列。仿真实验验证了本调度算法的闭环有效性,能在不同初始条件和外部扰动下依然获得最优调度序列,同时仿真结果证实降低碳排放限额或提高碳排放交易价格都有助于减少电网系统的总碳排放量。

北方煤矿矿井乏风余热回收换热器设计与试验

在煤矿乏风余热利用领域,换热器乏风风阻利用不充分,导致传热系数通常较低。针对以上问题,基于乏风压降不高于200 Pa的限制条件,进行了煤矿乏风余热利用换热器的设计。提出了基于换热管压降约束的圆管顺排设计方法,分析获得了竖-横向管心距比为5∶8的圆管顺排结构的换热器;二次开发了基于Excel VBA的多变量寻优、多方案比对的自动化方案决策工具,实现了陕煤榆林红柳林煤矿二号风井换热器等3个换热器近百个设计方案的选优,并在柠条塔煤矿南翼风井和红柳林煤矿二号风井完成了建造安装。红柳林煤矿二号风井安装的圆管顺排换热器的数据采集与分析表明,与合阳煤矿方管堆砌换热器传热系数17 W/(m^(2)·K)相比,其传热系数提升了近76%,达到30 W/(m^(2)·K);与红柳林煤矿原二号风井口锅炉年运行能耗7.65×10^(6) kWh相比,节约了近81%,仅为1.47×10^(6) kWh。圆管顺排换热器年实际热回收量为1.79×10^(6) kWh,柠条塔煤矿南翼风井换热器年实际热回收量为1.16×10^(6) kWh。将圆管顺排换热器在北方地区所有煤矿广泛推广后,预计每年可回收热能1.09×10^(10) kWh,减少8.64×10^(6) t二氧化碳、2.36×10^(6) t碳粉尘、2.6×10^(5) t二氧化硫、1.3×10^(5) t氮氧化物的排放。

对伴生放射性矿液态流出物排放限值确定的思考

为减少伴生放射性矿开发利用的辐射环境影响,需要限制伴生放射性废水处理后的液态流出物排放浓度。目前只有稀土行业制定了伴生放射性废水处理后的放射性排放浓度限值,其他伴生放射性矿行业需要执行《污水综合排放标准》。由于《污水综合排放标准》中放射性排放浓度限值的科学合理性存在争议,在伴生放射性矿开发利用活动中难以执行,因此急需制定伴生放射性矿废水处理后液态流出物排放限值的标准。本文通过研究伴生放射性矿废水的放射性的种类、浓度和放射性废水处理技术,调研国内外天然放射性核素的排放浓度限值,对科学制定伴生放射性矿开发利用企业液态流出物需控制的核素种类、排放限值进行了探讨,提出可以参考铀矿冶液态流出物的排放限值来制定伴生放射性矿液态流出物排放限值的思路,为制定我国伴生放射性矿开发利用的液态流出物排放限值标准提供建议。

苏州特别排放限值下城镇污水处理厂提标改造成效分析

为适应我国经济社会与生态环境形势的巨大变化,苏州市于2018年提出“苏州特别排放限值”。截至2020年底,苏州全市城镇污水处理厂均已完成提标改造工作。本研究根据苏州市80座城镇污水处理厂提标改造前后运行情况,通过研究处理规模、负荷率和出水水质等变化,分析本轮提标改造成效。结果表明,经本轮提标改造后,苏州市80座城镇污水处理厂总处理能力提升25.34%且负荷率分布趋于集中;化学需氧量、氨氮、总磷和总氮平均出水浓度分别下降19.81%、48.82%、34.47%和24.72%,平均去除率分别提高1.82%、1.43%、1.24%和9.48%,出水水质基本满足“苏州特别排放限值”要求;工程型与管理型提标改造措施均具有较好的成效。

正确认识园区限值限量监控体系理论与实践

本文通过对国内工业园区的发展现状与生态环境进行梳理,总结了企业环境管控和园区内部管理驱动的需求,从总体目标、管理要求、建设要求等角度阐述工业园区限值限量管理的重大理论和实践途径,并对工业园区限值限量政策落地提出了建议。