Fine particulate matter (PM2.5/PM1.0) in Beijing, China: Variations and chemical compositions as well as sources

Particulate matter (i.e., PM_1.0 and PM_2.5), 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 PM_1.0 and PM_2.5 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 PM_1.0 and PM_2.5 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.     

Chemical signature and fractionation of trace elements in fine particles from anthropogenic and natural sources

The health effects of trace metal elements in atmospheric fine particulate matter (PM_2.5) are widely recognized, however, the emission factor profiles and chemical fractionation of metal elements in different sources were poorly understand. In this study, sixteen metal elements, including Cd, Pb, V, Zn, Ba, Sb, As, Fe, Sr, Cr, Rb, Co, Mn, Cu, Ni and Sn from biomass burning, bituminite and anthracite combustion, as well as dust, were quantified. The results show different emission sources were associated with distinct emission profiles, holding important implications for source apportionment of ambient particulate metals. Specifically, Fe was the dominant metal species (28-1922 mg/kg) for all samples, and was followed by different metals for different samples. For dust, Mn (39.9 mg/kg_dust) had the second-highest emission factor, while for biomass burning, it was Cr and Ba (7.5 and 7.4 mg/kg_biomass, respectively). For bituminous coal combustion, the emission factor of Zn and Ba was 6.2 and 6.0 mg/kg_bituminous, respectively, while for anthracite combustion the corresponding emission factor was 5.6 and 4.3 mg/kg_anthracite, respectively. Moreover, chemical fractionation (i.e., the exchangeable, reducible fraction, oxidizable, and residual fraction) and the bioavailability index (BI) values of the metal elements from different sources were further investigated to reveal the link between different emission sources and the potential health risk. The findings from this study hold important implications for source apportionment and source-specific particulate metal-associated health effects.     

化工类技改项目环评中的清洁生产研究

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。     

Observations of microscopic characteristics of post-explosion coal dust samples

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 (P_max), the maximum rate of pressure rise ((dP/dt)_max), ignition time (t) and the deflagration index (K_St) 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.     

北京地区近300年降水变化的小波分析

利用北京地区1724-2009年降水资料,首先做了趋势分析和突变检验,之后采用Morlet小波函数,对该地区近300 a来降水的年际变化时间序列进行了小波分析,揭示了该区降水变化的多时间尺度的周期性变化规律,并根据主周期对未来降水变化进行了预测。结果表明,北京地区年降水量有缓慢增大的趋势,但并不显著。1744、1809、1894和1996年为该系列降雨量减少突变点,1777、1870和1948年为降雨量增多突变点。同时北京地区年降水量在其计算时域内各时间尺度分布不均匀,具有明显的局部化特征;年降水存在85~95 a左右时间尺度的周期特征;其次,35~40 a和20~25 a左右时间尺度的周期特征也较明显。降水量在不同时间尺度下偏多、偏少交替变化也各不相同。此外,分析结果显示该地区年降水量具有21 a、35 a和85 a左右的主周期,其中85 a周期为第一主周期;根据年降水的主周期推测,北京地区整个时间序列上的年降水量呈现出偏少-偏多-偏少-偏多-偏少-偏多-偏少的循环交替特征,根据其周期特征,可以推测2009年到2030年左右将一直处于少降水期。     

Equation for isotope accumulation in products and biomass as a way to reveal the pathways in mesophilic methanol methanization by microbial community

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.     

某有色金属企业污水处理厂污水处理工艺

对有色金属冶炼过程中产生的废水按特征因子的不同进行分质处理。其中,高浓度氨氮废水采用三级氨氮吹脱、吸收工艺进行脱氨预处理;含砷酸性废水采用三段中和-铁盐混凝法预处理;经预处理废水混合后,采用石灰法分级沉淀处理废水中重金属离子;然后根据各单位对回用水水质的不同要求,对废水进行深度处理,实现了污水处理后全部回用,污水零排放的目的。并且对污水中的氨、石膏、镍等资源进行回收利用,为企业降低了运行成本,并且防止了二次污染。     

中国代际降水区域变化差异分析

利用中国气象中心160站点的夏季降水实际观察资料,对中国半个世纪的降水变化按年代进行了系统分析,并对各地的代际降水量变化趋势进行了区域对比。结果发现,降水变化幅度大的区域主要集中在季风区,而非季风区的年代际降水相对稳定。在多数情况下,以四川为中心的区域的降水量变化与东北的北部一致,东南沿海与渤海湾沿岸区域一致。季风区降水量变化的区域差异,可能既受季风的年代际强弱变化的影响,又受微地形的影响：     

基于GIS的祁连山植被NDVI对气温降水的旬响应分析

利用祁连山地区SPOTVGT-NDVI数据和气象站点旬平均气温、降水资料,运用最大化合成、趋势线分析和相关分析方法分析了祁连山植被的时空变化趋势,并从旬时间尺度上分析了祁连山植被对气温和降水的响应特征。结果表明：近10年来．祁连山年最大化植被NDVI增加了3．1％,植被改善、无变化和退化的面积分别占总面积的70．21％、21．44％和8．35％。祁连山植被NDVI对气温变化的响应大于降水,对气温和降水变化的最大响应滞后都为2句左右。秋季植被NDⅥ对气温和降水变化响应最大,夏季植被NDVI对气温和降水响应的滞后期长于春季和秋季。祁连山植被NDVI对气温和降水变化的旬最大响应表现为中段大于东段和西段,NDVI对气温和降水变化的最大响应滞后期呈现出西段〉中段〉东段的空间分布特征。     

目前针对水环境化学品风险评估的方法是正确的么？

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