Emission factors of polycyclic aromatic hydrocarbons from domestic coal combustion in China

Domestic coal stove is widely used in China, especially for countryside during heating period of winter, and polycyclic aromatic hydrocarbons （PAHs） are important in flue gas of the stove. By using dilution tunnel system, samples of both gaseous and particulate phases from domestic coal combustion were collected and 18 PAH species were analyzed by GC-MS. The average emission factors of total 18 PAH species was 171.73 mg/kg, ranging from 140.75 to 229.11 mg/kg for bituminous coals, while was 93.98 mg/kg, ranging from 58.48 to 129.47 mg/kg for anthracite coals. PAHs in gaseous phases occupied 95% of the total of PAHs emission of coal combustion. In particulate phase, 3-ring and 4- ring PAHs were the main components, accounting for 80% of the total particulate PAHs. The total toxicity potency evaluated by benzo[a]pyrene-equivalent carcinogenic power, sum of 7 carcinogenic PAH components and 2,3,7,8-tetrachlorodibenzodioxin had a similar tendency. And as a result, the toxic potential of bituminous coal was higher than that of anthracite coal. Efficient emission control should be conducted to reduce PAH emissions in order to protect ecosystem and human health.     

长输油气管道工程建设对生态影响及对策研究

文章通过对东北地区长输油气管道工程建设可能产生的生态影响进行预测和分析,从工程建设的短期影响和长期影响两个方面,阐述长输油气管道工程建设对草原生态系统、湿地生态系统、森林生态系统、农田生态系统以及土壤所产生的生态影响,并从施工前期准备、施工期、施工后期恢复以及长期监测和管理等几个方面提出相应的对策和建议。     

基于系统动力学的辽宁省生态安全预警研究

基于P—S—R框架建立辽宁省城市生态安全预警评价指标体系,在此基础上,利用系统动力学方法构建辽宁省城市“资源-人口-经济-社会-环境”复合系统的生态安全预警模型,通过VENSIM仿真2010年至2020年的辽宁省城市生态安全预警指标趋势值,运用综合评价法对辽宁省14个城市进行生态安全预警评价。结果表明,未来10年生态安全预警评价结果分为3类：生态安全区、生态安全持续危险区和生态退化区。生态持续危险区和生态退化区属于生态安全预警区域,主要集中在辽宁省西北部。从辽宁省生态安全动态变化看,未来生态安全形势比较严峻。仿真结果表明基于系统动力学的生态安全预警结果可为辽宁省城市发展与建设提供一定的理论依据。     

基于GIS的乡镇干旱灾害风险评估与区划——以河北省唐山市滦县为例

以河北省唐山市滦县为例,基于乡镇气象资料历史序列的构建,利用AHP决策分析法和加权综合评价法,结合GIS空间分析技术,对滦县干旱灾害风险进行评估与区划。结果表明,旱灾高风险区多发生在东部古马镇、雷庄镇、响嘡镇、油榨镇等;轻度旱灾风险区一般发生在西部及西北部的山丘地区,如杨柳庄镇、九百户等乡镇。通过实际历史数据验证,滦县干旱灾害风险评估模型比较客观,能够全面反映出滦县的干旱灾害风险水平。对不同的风险区域采取针对性的防治措施,能够最大限度地减少干旱灾害带来的损失。     

基于典型省份对比的我国入境游客流量时间分布集中性计算与差异分析

客流量的时间分布集中性对旅游企业经营管理的季节性调整方略具有重要影响.选取了代表我国东部、西部、北部、南部、中部的5个典型省份的入境游客时间分布数据,分析了游客流量的时间集中性指数和高峰指数的内涵和变化状况,并对集中性指数的差异进行了简要的区域对比分析,为旅游企业季节性对策的确定提供参考.研究表明,客流量月强度指数Rm和中值月高峰指数Pmid较好地反映了客流量时间分布集中性.就区域而言,我国东部游客量的时间分布集中性小于西部,南部小于北部,沿海小于内陆.     

浅析八五七农场小城镇建设中的生态环境保护

以黑龙江垦区八五七农场小城镇建设为出发点,分析了八五七农场在小城镇建设中生态环境保护的实践经验,从环境规划、环保基础设施建设、污染防控、环境教育和环境监督管理方面,提出了小城镇建设中应注意的生态环境保护问题及建议。     

西安地铁双线隧道地表沉降预测模型研究

针对西安地铁留核心土、上下半洞开挖、超前小导管注浆加固与水平钢撑锁脚的钢拱架和挂网喷层支护的饱和黄土隧道,根据现场地面沉降监测数据,分析了隧道右线、左线掌子面间隔30m开挖过程中洞顶地表沉降变形的历时变化规律,以及左、右线单洞沉降槽和双线沉降槽的分布特征.结果表明,洞顶地表沉降变形可以划分为初期沉降变形、右线开挖主变形...     

高比表面积铜藻基活性炭的制备及工艺优化

以铜藻为原料,在对其进行元素含量、生化组成分析的基础上,分别采用ZnCl2活化法和H3PO4活化法制备活性炭,并以活性炭得率、碘吸附值、焦糖脱色率为指标,采用正交法考察了升温速率、活化温度、浸渍比(活化剂/铜藻质量比)等因素的影响,得到最佳工艺条件.同时,采用扫描电镜(SEM)、Brunauer-Emmet-Tller(BET)比表面积等方法分析活性炭特征.结果表明,铜藻原料粒度对制得的活性炭性能影响显著,106～180μm的颗粒较为适合.ZnCl2活化法制得的活性炭吸附性能明显优于H3PO4活化法;ZnCl2活化法的最佳工艺条件为:升温速率10℃.min-1、活化温度600℃、活化时间2h、浸渍比4,在保证活性炭得率超过30%的基础上,制备的活性炭比表面积为2314.58m2.g-1,碘吸附值为835.3mg.g-1,焦糖脱色率为110%,性能明显优于其他大型海藻原料所制备的活性炭,是陆地传统活性炭原料的有效补充.     

Influence of reactivation on the electrochemical performances of activated carbon based on coconut shell

Coconut shell-based activated carbon (AC) were prepared by CO₂ activation, and then the ACs with higher mesopore ratio were obtained by steam activation and by impregnating iron catalyst followed by steam activation, respectively. The AC with the highest mesopore ratio (AC_hmr) shows superior capacitive behavior, power output and high-frequency performance in supercapacitors. The results should attribute to the connection of its wide micropores and mesopores larger than 3 nm, which is more favorable for fast ionic transportation. The pore size distribution exhibits that the mesopore ratios of the ACs are significantly increased by reactivation of steam or catalyst up to 75% and 78%, respectively. As evidenced by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic measurements, the AC_hmr shows superior capacitive behaviors, conductivity and performance of electrolytic ionic transportation. The response current densities are evidently enhanced through the cyclic voltammery test at 50 mV/sec scan rate. The electrochemical impedance spectroscopy demonstrates that the conductivity and ion transport performance of the ACs are improved. The specific capacitances of the ACs were increased from 140 to 240 F/g at 500 mA/g current density. The AC_hmr can provide much higher power density while still maintaining good energy density, and demonstrate excellent high-frequency performances. The pore structure and conductivity of the AC_hmr also improve the cycleability and self-discharge of supercapacitors. Such AC_hmr exhibits a great potential in supercapacitors, particularly for applications where high power output and good high-frequency capacitive performances are required.     

Influence of reactivation on the electrochemical performances of activated carbon based on coconut shell

Coconut shell-based activated carbon (AC) were prepared by CO₂ activation, and then the ACs with higher mesopore ratio were obtained by steam activation and by impregnating iron catalyst followed by steam activation, respectively. The AC with the highest mesopore ratio (AC_hmr) shows superior capacitive behavior, power output and high-frequency performance in supercapacitors. The results should attribute to the connection of its wide micropores and mesopores larger than 3 nm, which is more favorable for fast ionic transportation. The pore size distribution exhibits that the mesopore ratios of the ACs are significantly increased by reactivation of steam or catalyst up to 75% and 78%, respectively. As evidenced by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic measurements, the AC_hmr shows superior capacitive behaviors, conductivity and performance of electrolytic ionic transportation. The response current densities are evidently enhanced through the cyclic voltammery test at 50 mV/sec scan rate. The electrochemical impedance spectroscopy demonstrates that the conductivity and ion transport performance of the ACs are improved. The specific capacitances of the ACs were increased from 140 to 240 F/g at 500 mA/g current density. The AC_hmr can provide much higher power density while still maintaining good energy density, and demonstrate excellent high-frequency performances. The pore structure and conductivity of the AC_hmr also improve the cycleability and self-discharge of supercapacitors. Such AC_hmr exhibits a great potential in supercapacitors, particularly for applications where high power output and good high-frequency capacitive performances are required.