共查询到19条相似文献，搜索用时 656 毫秒
1.
中国科学院"大气灰霾追因与控制"专项总体组 《中国科学院院刊》2015,30(5):668-678
2013年9月13日,国务院颁布了《大气污染防治行动计划》(简称"大气国十条"),提出了京津冀地区2017年PM2.5浓度比2012年下降25%,北京市PM2.5年均浓度控制在60μg/m3左右的目标。"大气国十条"实施以来,北京、天津和河北相继出台了对应的行动计划,分别从"控煤"、"控车"、"控尘"、"控工业污染"和"控新建项目污染"等方面部署了防治措施。中科院"大气灰霾追因与控制"研究团队从观测和模拟的角度对该区域控制措施的实际效果开展了评估,以期为后续防治措施的制定提供参考。与2013年相比,京津冀2014年SO2和NO2大气平均浓度下降约20%,PM2.5大气平均浓度下降约10%;其中河北SO2、NO2和PM2.5的下降幅度最显著。上述污染物浓度在冬季比夏季降低更显著。与2013年冬季相比,京津冀2014年冬季PM2.5中硫酸盐的比例略有下降,硝酸盐的比例略有增加。模式模拟表明,2013年和2014年该区域气象场无明显变化,由于控制措施的实施导致污染物排放清单的变化,进而导致2014年冬季京津冀PM2.5浓度下降,但对夏季PM2.5浓度无有利影响,并存在臭氧污染的潜在风险,与观测结果吻合。在实施京津冀大气污染联防联控过程中,控制重点应向河北倾斜。 相似文献
2.
《内江科技》2020,(7)
本文利用MODIS 3 km AOD产品对2015年福州地区PM_(2.5)浓度进行遥感估算,结果表明卫星遥感AOD和PM_(2.5)浓度之间的相关系数为0.316。由于AOD和PM_(2.5)浓度受气候条件的影响,因此本文基于MODIS 3 km AOD,进一步构建了线性混合效应模型(LME)来估算福州地区的近地面PM_(2.5)浓度。结果表明,由LME模型估算的PM_(2.5)浓度值和地面监测值的相关系数达到了0.89。研究结果表明,基于MODIS 3 km AOD估算地面PM_(2.5)浓度的LME模型能较好地应用于城市地区的PM_(2.5)监测。 相似文献
3.
北京城市绿地对大气PM_(2.5)的削减作用 总被引：1，自引：0，他引：1
PM2.5导致的大气污染已经成为中国经济快速发展地区共同面临的问题。城市绿地对削减大气PM2.5具有一定的作用。本研究基于NDVI数据模拟北京城市绿地叶面积指数,再利用干沉降模型模拟区域绿地PM2.5削减量,最后根据大气PM2.5存量计算了绿地对大气PM2.5的去除效果。研究结果显示,2000年、2005年和2010年北京城市绿地PM2.5削减总量分别为1 861t、2 987t和3 852t,单位面积削减量分别为22.71kg/hm2、24.64kg/hm2和33.36kg/hm2,可分别将研究区内PM2.5削减0.07%、0.12%和0.19%。苗圃与果园、社区林和路旁林的PM2.5削减总量较高,而针阔混交林、灌木林和针叶林的单位面积削减量较高。五环以外绿地的PM2.5削减总量、单位面积削减量和大气PM2.5去除率都高于五环以内绿地。本研究可以为北京城市规划中更好发挥绿地缓解大气PM2.5作用提供决策依据。 相似文献
4.
选取杭州地区5组两两临近的气象部门与环保部门大气成分观测站点资料,以2015年12月1日～2016年11月30日两个部门的日平均PM_(2.5)浓度观测值为样本,对"气象部门日平均PM_(2.5)浓度"与"环保部门日平均PM_(2.5)浓度"两个总体的一致性进行评估。得到分析结果如下:(1)两种来源的PM_(2.5)观测年平均浓度相差较小,5组站点的平均绝对偏差为2. 20μg/m3,平均相对偏差为3. 71%;(2)两种来源的PM_(2.5)浓度观测值随时间的变化趋势一致,两者时间序列的相关系数达到0. 64;(3)两种来源的日平均PM_(2.5)浓度值差异大小存在一定的季节变化,这一差值在7～11月间于0值附近摆动,说明在此期间两个部门观测数据的一致性好于其他月份;(4)通过基于t检验的逐对比较法检测两种来源日平均PM_(2.5)浓度的观测值是否存在固有差异,可知当置信水平为99. 5%时,可以判断该种差异是存在的。总体而言,气象与环保部门的PM_(2.5)浓度观测在一定时间域内有一致的量值和趋势,但具体到每日的观测而言,两种来源存在一定的固有差异。推测这种差异的存在原因,可能是由不同部门观测仪器、观测方法等不同而引起的。 相似文献
5.
《中国科技信息》2016,(16)
利用厦门市国控环境空气质量自动监测站点2013—2015年PM_(10)、PM_(2.5)监测数据,深入分析了厦门市环境空气中PM_(10)和PM_(2.5)浓度的年、周、日变化特征。结果表明,厦门市PM_(10)、PM_(2.5)浓度具有单峰型年变化特征,10月至次年5月颗粒物(PM_(10)、PM_(2.5))浓度较高,6月至9月浓度较低。PM_(10)、PM_(2.5)浓度变化未出现"周末效应"。PM_(10)、PM_(2.5)浓度具有单峰型日变化特征,尤以冬季日变化特征最为显著,PM_(10)、PM_(2.5)高浓度时段出现在7:00—12:00。不同月份PM_(2.5)在PM_(10)中的占比介于54%~73%之间,PM_(2.5)/PM_(10)比值7月最低,2月最高。PM_(2.5)/PM_(10)比值存在显著的双峰型日变化特征,峰值分别出现在04:00、14:00,谷值出现在10:00、19:00。 相似文献
6.
《科技风》2020,(1)
本文利用新郑市2018年的降水量资料和降水天气出现前后空气的PM_(10)和PM_(2.5)浓度变化数据,分析降水对新郑市大气污染湿沉降特征。结果表明:2018年新郑市的74次降水天气过程对PM_(10)和PM_(2.5)的平均清除效率分别为12.6%、16.5%,大部分的降水天气对空气中的PM_(10)清除效果要比PM_(2.5)差,不管降水强度如何,其对于空气中的扬尘、沙尘等大粒径颗粒物的清除效果相对较好;新郑市的弱降水天气过程共出现31次,其中有13次的降水天气过程中增加了PM_(10)浓度,降水过程对PM_(10)的平均清除效率为8.0%;其中有10次降水增加了PM_(2.5)浓度,降水过程对PM_(2.5)的平均清除效率为-11.0%;新郑市超过1.5mm的降水天气过程共有43次,占总降水天气过程的41.9%,但是大部分降水过程对空气中的PM_(10)和PM_(2.5)浓度以正清除效率效率为主;随着小时最大降水量的增加,降水对空气中的PM_(10)和PM_(2.5)清除效果会不断增大;因降水天气过程对PM_(10)的清除效果要低于PM_(2.5),使得降水天气结束后PM_(2.5)/PM_(10)比率要低。 相似文献
7.
《内蒙古科技与经济》2021,(13)
选取2019年6月1日-2019年8月31日呼和浩特市小召环监站PM(PM_(2.5)和PM_(10))的监测数据,分析了呼和浩特市夏季PM_(2.5)和PM_(10)的变化特征。结果表明:PM_(2.5)呈不规则多峰型日变化特征,PM_(10)日变化主要呈双峰型变化;PM_(2.5)小时平均质量浓度日循环在工作日呈不规则多峰型分布,周末呈三峰型分布;PM_(10)小时平均质量浓度日循环在工作日与周末均呈现三峰型分布;PM_(2.5)周末效应比PM_(10)更加明显。 相似文献
8.
近年来,随着某市经济的快速发展和工业化、城镇化进程的加快,环境问题已成为社会民众关心的热点问题,这方面又以PM_(2.5)热度最高。文章结合2013年全年某市六个常规大气环境监测站的污染因子、气象因子数据,重点从统计角度研究分析某市PM_(2.5)浓度的数据分布、时空变化特点及其与大气污染浓度变化和气象因子的相关性,同时结合站点布局分析其与PM_(2.5)监测数据的联系,进一步提出优化常规大气环境监测点布局选址方案的模式。通过站点布局优化形成相互联系的监测网络,将为环境监测提供更为可靠的代表数据,为环境保护管理决策提供新的思路。 相似文献
9.
利用湖州3个大气成分监测站的2013-2015年污染物监测数据,分析了O_3浓度的变化特征,讨论了O_3浓度与五种污染物(PM_(2.5)、PM_(10)、NO_2、CO和SO_2)的相关性。研究发现:年O_3浓度频率呈类指数衰减分布特征,二级标准年超标率为5.99%;O_3表现出明显的季节变化特征,夏季、春季是湖州高浓度O_3易发季节,夏季超标率最高,达到10.73%,冬季超标率接近0;月平均O_3浓度呈双峰型分布,峰值浓度出现在5月和9月;日平均O_3浓度谷值和峰值分别出现在6时和15时,且冬季日变化幅度明显小于其它3个季节;O_3与PM_(2.5)、NO_2负相关明显,与SO_2变化趋势相似,一般比SO_2滞后6 h。 相似文献
10.
11.
Yonghong Wang Wenkang Gao Shuai Wang Tao Song Zhengyu Gong Dongsheng Ji Lili Wang Zirui Liu Guiqian Tang Yanfeng Huo Shili Tian Jiayun Li Mingge Li Yuan Yang Biwu Chu Tuukka Petj Veli-Matti Kerminen Hong He Jiming Hao Markku Kulmala Yuesi Wang Yuanhang Zhang 《国家科学评论(英文版)》2020,7(8):1331
Although much attention has been paid to investigating and controlling air pollution in China, the trends of air-pollutant concentrations on a national scale have remained unclear. Here, we quantitatively investigated the variation of air pollutants in China using long-term comprehensive data sets from 2013 to 2017, during which Chinese government made major efforts to reduce anthropogenic emission in polluted regions. Our results show a significant decreasing trend in the PM2.5 concentration in heavily polluted regions of eastern China, with an annual decrease of ∼7% compared with measurements in 2013. The measured decreased concentrations of SO2, NO2 and CO (a proxy for anthropogenic volatile organic compounds) could explain a large fraction of the decreased PM2.5 concentrations in different regions. As a consequence, the heavily polluted days decreased significantly in corresponding regions. Concentrations of organic aerosol, nitrate, sulfate, ammonium and chloride measured in urban Beijing revealed a remarkable reduction from 2013 to 2017, connecting the decreases in aerosol precursors with corresponding chemical components closely. However, surface-ozone concentrations showed increasing trends in most urban stations from 2013 to 2017, which indicates stronger photochemical pollution. The boundary-layer height in capital cities of eastern China showed no significant trends over the Beijing–Tianjin–Hebei, Yangtze River Delta and Pearl River Delta regions from 2013 to 2017, which confirmed the reduction in anthropogenic emissions. Our results demonstrated that the Chinese government was successful in the reduction of particulate matter in urban areas from 2013 to 2017, although the ozone concentration has increased significantly, suggesting a more complex mechanism of improving Chinese air quality in the future. 相似文献
12.
Junting Zhong Xiaoye Zhang Ke Gui Yaqiang Wang Huizheng Che Xiaojing Shen Lei Zhang Yangmei Zhang Junying Sun Wenjie Zhang 《国家科学评论(英文版)》2021,8(10)
Retrieving historical fine particulate matter (PM2.5) data is key for evaluating the long-term impacts of PM2.5 on the environment, human health and climate change. Satellite-based aerosol optical depth has been used to estimate PM2.5, but estimations have largely been undermined by massive missing values, low sampling frequency and weak predictive capability. Here, using a novel feature engineering approach to incorporate spatial effects from meteorological data, we developed a robust LightGBM model that predicts PM2.5 at an unprecedented predictive capacity on hourly (R2 = 0.75), daily (R2 = 0.84), monthly (R2 = 0.88) and annual (R2 = 0.87) timescales. By taking advantage of spatial features, our model can also construct hourly gridded networks of PM2.5. This capability would be further enhanced if meteorological observations from regional stations were incorporated. Our results show that this model has great potential in reconstructing historical PM2.5 datasets and real-time gridded networks at high spatial-temporal resolutions. The resulting datasets can be assimilated into models to produce long-term re-analysis that incorporates interactions between aerosols and physical processes. 相似文献
13.
Jing Cheng Dan Tong Qiang Zhang Yang Liu Yu Lei Gang Yan Liu Yan Sha Yu Ryna Yiyun Cui Leon Clarke Guannan Geng Bo Zheng Xiaoye Zhang Steven J Davis Kebin He 《国家科学评论(英文版)》2021,8(12)
Clean air policies in China have substantially reduced particulate matter (PM2.5) air pollution in recent years, primarily by curbing end-of-pipe emissions. However, reaching the level of the World Health Organization (WHO) guidelines may instead depend upon the air quality co-benefits of ambitious climate action. Here, we assess pathways of Chinese PM2.5 air quality from 2015 to 2060 under a combination of scenarios that link global and Chinese climate mitigation pathways (i.e. global 2°C- and 1.5°C-pathways, National Determined Contributions (NDC) pledges and carbon neutrality goals) to local clean air policies. We find that China can achieve both its near-term climate goals (peak emissions) and PM2.5 air quality annual standard (35 μg/m3) by 2030 by fulfilling its NDC pledges and continuing air pollution control policies. However, the benefits of end-of-pipe control reductions are mostly exhausted by 2030, and reducing PM2.5 exposure of the majority of the Chinese population to below 10 μg/m3 by 2060 will likely require more ambitious climate mitigation efforts such as China''s carbon neutrality goals and global 1.5°C-pathways. Our results thus highlight that China''s carbon neutrality goals will play a critical role in reducing air pollution exposure to the level of the WHO guidelines and protecting public health. 相似文献
14.
提升油品质量、降低机动车污染物排放,对改善我国空气质量至关重要。通过隧道试验测试了道路机动车污染物排放水平,从我国8大城市加油站收集的汽柴油样品实测了其硫含量和烃类组成等指标,用先进的烟雾箱系统模拟了汽油车和柴油车尾气直接排放和二次反应生成的颗粒物,并探讨了机动车尾气对细颗粒物(PM2.5)的综合贡献与油品之间的关系。在分析我国油品升级所需的脱硫、重整、加氢等技术需求的基础上,初步估算了我国汽柴油全面升级的直接投资需求。文章也揭示了突破柴油发动机和柴油深加工技术对我国机动车减排的重要意义。 相似文献
15.
通过收集各渠道资料,分析近年来有关新型科研机构的政策、文件、调研等一系列活动,指出新型科研机构已成为今后发展的重要方面;并通过对国内新型科研机构的发展举措和动向进行梳理,提出促进新型科研机构发展的相关建议。 相似文献
16.
Babul Bandyopadhyay Sandip K Bandyopadhyay 《Indian journal of clinical biochemistry : IJCB》1998,13(1):41-45
Prostaglandins and (PG) have been reported to be an important gastric acid suppressive factor. However, the mechanism underlying
is yet to be clearly established. In vitro study with gastric microsomes in presence of both PGE2 and PGI2 shows a stimulation of gastric H+ K+-ATPase activity below 1X10−6M and 2.5X10−7M concentrations respectively. However, with further increase in concentrations of both PGE2 and PGI2, H+, K+-ATPase activity shows an inhibition but PGI2 completely obliterates the K+ stimulated part of H+, K+-ATPase activity at higher concentration. The H+-ion transport study using chambered frog gastric mucosa shows that both PGE2 and PGI2 inhibit H+-ion transport at 5X10−6 M and 10X10−6M concentrations respectively but the effect of PGI2 is reversible. These differential effects of PGE2 and PGI2 on microsomal H+, K+-ATPase and on H+ transport my be caused by the differential effects of these phospholipid mediators with the gastric mucosal cell membrane.
This in vitro investigation shows the role of prostaglandin (s) as a physiological switch/regulator of gastric H+ ion transport leading to the cessation of gastric acid secretion. 相似文献
17.
Nosratollah Zarghami Mohammad Rohbani-Noubar Ali Khosrowbeygi 《Indian journal of clinical biochemistry : IJCB》2005,20(2):182-185
Pregnancy is associated with significant, but reversible changes in thyroid function studies, which are among the most profound
seen as a result of a normal physiologic state. The present study was carried out to find out alterations in thyroid function
tests in each trimester in normal pregnant women as compared to non-pregnant women in Tabriz-Iran. A case-control study designed
with 229 normal pregnant women that randomly selected from the first (64 samples), the second (92 samples), and the third
(73 samples) trimesters and 250 randomly selected non-pregnant healthy female controls. Age range in both groups was 16–40
years. Thyroid function tests carried out by measuring serum levels of thyroid stimulating hormone (TSH), free and total thyroxin
(FT4, TT4), and free and total triiodothyronine (FT3, TT3) by commercially available radio immunoassay kits. We found that mean TT4 increased progressively during pregnancy. Our study showed increasing in serum levels of TT3 in the second trimester and then declining during the third trimester compared with non-pregnant women. We showed that FT4 strongly decreased during the third trimester. Free T3 showed declining in the second and third trimesters. Mean TSH did not show significant difference in each trimester compared
with non-pregnant women. The thyroid function tests in pregnancy should be interpreted against gestational age-related reference
intervals to avoid mis-interpretation of thyroid function during pregnancy. 相似文献
18.
太原地区冬春季PM2.5污染特征及影响因素 总被引：4，自引：0，他引：4
采用美国R&;P公司生产的TEOM系列1400A大气粒子（PM2.5）监测仪于2005年12月17日至2006年3月28日对太原地区PM2.5质量浓度进行在线观测。对观测期间2417个PM2.5小时平均浓度观测数据进行分析，得到小时平均浓度的平均值是247.6µg/m3(193.7 µg/m3)。在50-100µg/m3之间的PM2.5浓度出现的频率最高，PM2.5小时平均浓度小于400 µg/m3的频率为84.1%。PM2.5浓度日变化为双峰双谷型。太原市区PM2.5浓度与风速、能见度和气压呈负相关，与相对湿度呈正相关。通过3d 后向轨迹分析了影响太原地区气团的主要传输路径，结果表明，100 m高度上空的后向轨迹可划分为7种基本类型，其中第3类轨迹对应的PM2.5浓度值为342.6 µg/m3，明显高于其它类型。这类轨迹主要是来自太原的西南方向；而来自东边方向的第1类轨迹对应的PM2.5浓度为261.1 µg/m3，也比来自西北方向的2、4类轨迹PM2.5浓度高。观测结果表明在沙尘暴影响严重的日期，太原地区PM2.5浓度会极大地增加，从而对大气环境形成严重的污染。 相似文献
19.
本文构建了能源消费的生态与环境压力指数评价方法,对北京全市及各主体功能区能源消费的生态与环境压力进行定量评估。评估结果表明,北京市2005-2010年的生态与环境压力指数从32.2上升为33.4,生态与环境压力仍处于不断加大阶段,其中能源消费的生态足迹和PM2.5排放对生态与环境压力指数上升的贡献较大。各主体功能区之间能源消耗的生态环境压力差异较大,生态与环境压力从核心区向外快速递减,2010年首都功能核心区的生态与环境压力指数为3 983.48,分别是城市功能拓展区、城市发展新区以及生态涵养发展区的12、91和1 062倍,除生态涵养发展区外,其他三大功能区的生态压力均占生态与环境综合压力的90%以上,生态压力突出。此外,在2005-2010年期间,除生态涵养发展区能耗的生态与环境压力略有降低外。首都功能核心区、城市功能拓展区和城市发展新区能耗的生态与环境压力均呈现增大趋势,分别增大了25%,7%和22%。 相似文献