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841.
Hezhong Tian Lining Luo Xiaoxuan Bai Shuhan Liu Bobo Wu Wei Liu Yunqian Lv Zhihui Guo Shumin Lin Shuang Zhao Yan Hao Jiming Hao Kai Zhang Aihua Zheng 《环境科学学报(英文版)》2022,34(11):187-198
Particulate matter (i.e., PM1.0 and PM2.5), considered as the key atmospheric pollutants, exerts negative effects on visibility, global climate, and human health by associated chemical compositions. However, our understanding of PM and its chemical compositions in Beijing under the current atmospheric environment is still not complete after witnessing marked alleviation during 2013–2017. Continuous measurements can be crucial for further air quality improvement by better characterizing PM pollution and chemical compositions in Beijing. Here, we conducted simultaneous measurements on PM in Beijing during 2018–2019. Results indicate that annual mean PM1.0 and PM2.5 concentrations were 35.49 ± 18.61 µg/m3 and 66.58 ± 60.17 µg/m3, showing a positive response to emission controls. The contribution of sulfate, nitrate, and ammonium (SNA) played an enhanced role with elevated PM loading and acted as the main contributors to pollution episodes. Discrepancies observed among chemical species between PM1.0 and PM2.5 in spring suggest that sand particles trend to accumulate in the range of 1–2.5 µm. Pollution episodes occurred accompanied with southerly clusters and high formation of SNA by heterogeneous reactions in summer and winter, respectively. Results from positive matrix factorization (PMF) combined with potential source contribution function (PSCF) models showed that potential areas were seasonal dependent, secondary and vehicular sources became much more important compared with previous studies in Beijing. Our study presented a continuous investigation on PM and sources origins in Beijing, which provides a better understanding for further emission control as well as a reference for other cities in developing countries. 相似文献
842.
本文将某化工厂环评当作主要论述对象,充分彰显出清洁生产分析应当有机地同工程分析结合起来,这样做的目的是为了促使企业生产实现节能、降耗的目的,取得环境与经济效益互利共赢的效果,还能强化环评的可行性与有效性。 相似文献
843.
Venting is an effective way to prevent harmful dust explosions, but the existing prediction methods are imprecise and are suitable only for applications with low activation pressures. A new method is proposed for predicting pressures based on an analysis of energy losses at high activation pressures and verified by aluminum dust explosion experiments. Compared with the experimental results, the results of the new model are relatively stable under working conditions with different activation pressures and venting areas. Based on the analysis of energy losses, the changes in the energy loss rate, temperature, and venting velocity during venting are found to be asynchronous. The thermal energy loss, which accounts for over 80 percent of the total, is expected to be larger than the kinetic energy loss. The thermal energy loss rate changes rapidly during venting, while the kinetic energy loss rate remains relatively stable. The new model is more accurate than the NFPA68 standard, which fails to consider the thermal energy loss. Neglecting the thermal energy loss may result in an underestimation of the pressure reduction; this error increases with decreasing activation pressure. 相似文献
844.
To reveal the microscopic characteristics of the post-explosion coal dust samples, coal dust explosion tests were performed in a 20 L spherical vessel. The explosion characteristic parameters, such as the maximum pressure (Pmax), the maximum rate of pressure rise ((dP/dt)max), ignition time (t) and the deflagration index (KSt) were recorded. Meanwhile, the post-explosion dust samples were collected and analyzed. The research efforts include particle size distribution analysis, SEM analysis and FTIR analysis of dust samples before and after the explosion. The particle size range of post-explosion dust samples became wider according to the mass percent analysis. The microscopic appearance of samples in same particle size range showed some similarity. The porous structure of dust samples was observed by improving the SEM magnification. The chemical structure of dust samples before and after explosion was analyzed by FTIR. 相似文献
845.
采用杭嘉湖地区典型的小粉土和青紫泥土壤,进行水稻盆栽试验,研究新型硝化抑制剂3,4-二甲基吡唑磷酸盐(DMPP)对稻田田面水氮素转化及径流流失潜能的影响.结果表明,小粉土和青紫泥土壤稻田应用添加DMPP抑制剂的尿素,与常规尿素处理相比,田面水中铵态氮的浓度增加24.8%和16.7%,硝态氮浓度降低47.7%和70.9%,亚硝态氮浓度降低90.6%和88.9%,总无机氮浓度下降13.5%与23.1%,能显著减轻农田氮素流失对水环境存在的污染;DMPP可使田面水的电导率下降,降低盐基离子随农田排水或暴雨径流所导致的流失风险,有助于保护河流水体等地表水环境. 相似文献
846.
V.A. Vavilin 《Ecological modelling》2010,221(24):2881-2886
Isotope-labelling of substrate is used to reveal the methabolic pathways of substrate transformation by microbial community. In this paper, in order to describe the batch mesophilic anaerobic methanization of 13C-labelled methanol and microbial ecology analysis (Li et al., 2008), an equation for the isotope accumulation in products and biomass was included into the basic mathematical model based on stoichiometric chemical reactions. The higher was the isotope level in substrate, the larger fraction of 13C accumulated in products and biomass. Acetate, total organic and inorganic carbon (TOC, TIC) concentrations and methane production were used for the model calibration, whereas 13C enrichment of acetate, TIC and biomass were used for model validation. In the model, chemical transformations including methanol and acetate oxidation, homoacetogenesis, hydrogenotrophic and aceticlastic methanogenesis were considered. The rate-limiting reactions were methanol and acetate consumption. According to the model, homoacetogens performing acetate formation and oxidation were competed with hydrogenotrophic methanogens for hydrogen. Biphasic methane production was due to hydrogenotrophic methanogenesis in the first phase and due to acetiticlastic and hydrogenotrophic methanogenesis following acetate oxidation in the second phase. 相似文献
847.
我们想要保护水生生态环境,通过测试数以千计的化学物质和成百上千的水生物种之间交互作用,得到成千上万的结果,但仍然不可能考虑到所有物质的混合情况。污染物对野生鱼类的内分泌干扰作用的课题推动了人们对如药物之类的微污染物的研究。尽管我们担心鱼类会因污染而繁殖能力下降,但并没有足够的证据表明鱼类种群处于危险之中。事实上,许多鱼类生物学家认为,在过去的30 - 40年里,鲤科的数量已经在逐步恢复中。目前的风险评估的关键在于其核心假设,也就是实验室观测或者模型预测的结果简单地适用于群体水平,显而易见这个假设是值得质疑的。
我们明白了疏于监测野生动物种群的变化成为了我们的环境保护战略的关键弱点。如果我们不知道水生野生动物物种是在减少或增加,那么我们研究的其他生态毒理行为又有多少价值呢?
精选自Andrew C. Johnson, John P. Sumpter. Are we going about chemicals risk assessment for the aquatic environment the wrong way?. Environmental Toxicology and Chemistry: Volume 35, Issue 7, pages 1609–1616, July 2016.
DOI: 10.1002/etc.3441
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3441/full 相似文献
848.
基于2013年1月期间全国20个受到雾霾事件影响的省市的公开报道数据,综合采用直接损失评估法、疾病成本法和人力资本法,对雾霾事件造成的交通和健康直接经济损失进行评估.评估结果显示,2013年1月雾霾事件造成的全国交通和健康的直接经济损失保守估计约230亿元,其中损失最大的省市主要分布在东部和京津冀区域;雾霾事件中仅急/门诊的健康终端的经济损失占总直接损失的98%,相当于现有文献研究结果中对非雾霾事件情况下颗粒物污染造成的所有健康终端损失的近2倍. 相似文献
849.
850.