Emission source-based ozone isopleth and isosurface diagrams and their significance in ozone pollution control strategies

In the past decade, ozone (O₃) pollution has been continuously worsening in most developing countries. The accurate identification of the nonlinear relationship between O₃ and its precursors is a prerequisite for formulating effective O₃ control measures. At present, precursor-based O₃ isopleth diagrams are widely used to infer O₃ control strategy at a particular location. However, there is frequently a large gap between the O₃-precursor nonlinearity delineated by the O₃ isopleths and the emission source control measures to reduce O₃ levels. Consequently, we developed an emission source-based O₃ isopleth diagram that directly illustrates the O₃ level changes in response to synergistic control on two types of emission sources using a validated numerical modeling system and the latest regional emission inventory. Isopleths can be further upgraded to isosurfaces when co-control on three types of emission sources is investigated. Using Guangzhou and Foshan as examples, we demonstrate that similar precursor-based O₃ isopleths can be associated with significantly different emission source co-control strategies. In Guangzhou, controlling solvent use emissions was the most effective approach to reduce peak O₃ levels. In Foshan, co-control of on-road mobile, solvent use, and fixed combustion sources with a ratio of 3:1:2 or 3:1:3 was best to effectively reduce the peak O₃ levels below 145 ppbv. This study underscores the importance of using emission source-based O₃ isopleths and isosurface diagrams to guide a precursor emission control strategy that can effectively reduce the peak O₃ levels in a particular area.     

Seasonal bioconcentration of heavy metals in Onchidium struma （Gastropoda： Pulmonata） from Chongming Island, the Yangtze Estuary, China

The seasonal concentration changes of selected heavy metal Cd, Cr, Cu, Fe, Mn, Pb, and Zn in five tissues of marine gastropod Onchidium struma were studied in the Chongming Island, the Yangtze Estuary on July 2006, September 2006, and November 2006, April 2007, respectively. The results demonstrated that the bioconcentration factor of Cu (biomass/water) in all selected tissues was about 104 magnitudes, Fe and Cd were 103, Zn was 102, and Mn, Pb, and Cr were 101. Hepatopancreas was proven to be the dominant storage tissue of Cr, Cu, Mn, and Zn, whereas Fe and Pb were mainly stored in muscle and digenetic gland, and Cd was stored in vitelline gland and albumen gland. Additionally, it was found that Cu, Fe, Mn, and Zn were concentrated significantly by O. struma (whole-body) in summer or autumn, and Cd, Cr, and Pb increased slightly in spring and winter. Furthermore, the bioconcentration of Cr was nearly 2-fold higher and Zn was 1.6-fold higher in the water compared with the Water Quality Standard for Fisheries. With view of excessive amount of Pb, Cd, and Cu according to seafood standard, the consumption of O. struma might have the risk of health hazard.     

青藏高原东缘冬季PM2.5中碳组分特征和来源解析

于2017年冬季12月13—21日在青藏高原东缘理塘地区分昼夜采集PM_2.5样品,并用DRI2001A热光碳分析仪测定了有机碳(OC)和元素碳(EC)的质量浓度,研究青藏高原PM_2.5中碳组分的化学特征及主要来源,以期为理塘地区制定污染排放政策提供参考。结果表明,2017年冬季青藏高原东缘理塘地区PM_2.5平均质量浓度为44.34μg·m^?3,OC和EC的质量浓度为12.72μg·m^?3和3.85μg·m^?3,分别占PM_2.5质量浓度的29.61%和8.96%。通过经验公式,计算得到总碳气溶胶(TCA)质量浓度为24.20μg·m^?3,占PM_2.5的54.84%,说明碳质气溶胶对青藏高原东缘理塘地区PM_2.5有着十分重要的贡献。OC和EC在白天和夜间都有较高的相关性(相关系数分别为0.74和0.91),表明OC和EC的来源基本一致,受燃烧源影响较大。其中白天的相关系数低于夜间,说明青藏高原东缘理塘地区白天碳组分来源相对复杂。昼夜浓度对比显示,青藏高原东缘理塘地区PM_2.5白天和夜间的质量浓度分别为53.88μg·m^?3和33.44μg·m^?3,OC和EC浓度白天高于夜间,表明白天人为排放相对较高。冬季观测期间,PM_2.5中二次有机碳(SOC)昼夜浓度分别为1.11μg·m^?3和3.03μg·m^?3,分别占OC质量浓度的7.09%、26.59%,表明青藏高原东缘理塘城区白天碳组分主要为一次源。利用PMF 5.0软件对理塘城区碳组分进行进一步的解析,结果显示燃煤和生物质燃烧的混合源对总碳(TC)的贡献高达47.84%,占比最高;其次是汽车尾气和柴油车尾气源,贡献率分别为28.62%和23.54%。     

信息素调控质粒介导的粪肠球菌耐药基因接合转移机制研究进展

粪肠球菌是一种在自然环境中广泛存在的革兰氏阳性细菌.由于其特殊的耐药机制及高频率的耐药基因转移方式,导致了环境中耐药粪肠球菌的广泛传播,生态安全形势严峻.其中,信息素应答质粒介导的粪肠球菌耐药基因的接合转移是造成粪肠球菌耐药基因快速扩散的重要方式.本文回顾了近些年关于信息素应答质粒接合转移的研究成果,分析总结了接合转移的必要条件、正负调控信息素对接合转移的调节作用,并以携带四环素抗性的质粒pCF10为例简要探讨了接合转移相关基因、蛋白的调控机制,旨在更加全面地揭示粪肠球菌的耐药基因传播机制,为耐药细菌的基因转移机制研究提供参考.     

城市生活垃圾处理技术现状与管理对策

近年来,我国城市生活垃圾产生量每年以约10%的速度迅猛增长,而城市生活垃圾处理能力发展相对滞后。客观评述城市生活垃圾常用的填埋、焚烧、堆肥3种处理技术的优缺点和在国内的应用现状,并针对城市生活垃圾在收运、处理以及管理等环节中存在的突出问题,提出了明确的建议与措施：首先,完善相关法规政策,实施分类收集,加强源头控制;其次,创新管理体制,推行市场化运作机制,政府加强政策引导和监督;再次,按照＂谁污染,谁付费＂的原则,建立健全垃圾收费体系;最后,充分利用各种媒介,加大宣传力度,提高公众环保意识。同时,还探讨了城市生活垃圾处理技术发展的趋势。焚烧处理将是今后一段时期我国最有发展潜力的技术,气化熔融焚烧技术是一种高效资源化、污染物接近零排放的新型焚烧技术;生物反应器填埋技术可减少渗滤液处理量、降低垃圾处理成本,具有广阔的发展前景;堆肥技术可作为焚烧或填埋之前的预处理手段;城市生活垃圾综合处理集多种处理技术的优点于一体,在节约处理成本,提高经济效益的同时,实现了垃圾的减量化、资源化、无害化,是未来我国生活垃圾处理的优先发展方向。     

南京市环境空气挥发性有机物监测方法比对研究

2018年9月20—29日,开展了南京市环境空气非甲烷烃(PAMS)原清单中57种挥发性有机物的手工和在线比对监测,监测项目主要包括碳氢化合物、卤代烃和含氧挥发性有机物。通过对VOCs 3 h均值、日均值和主要污染物指标等进行比对,分析在线监测数据与手工监测数据的相关性。测试结果表明,两种方法得到的3 h均值的差异度(1.43)和相关系数(0.897),日均值的差异度(2.16)和相关系数(0.946),呈现出差异度不显著、高度线性相关的特征。同时,进一步分析了监测数据产生偏离的原因,建议加强环境空气手工监测的质控管理,强化在线监测设备的运维管理,推进环境空气挥发性有机物监测的合理、有序发展。     

2014年“国家公祭日”保障期间南京PM2.5中碳组分污染特征

利用2014年“国家公祭日”期间南京市草场门测点OC和EC在线监测仪器,分析了PM_2.5中碳组分污染特征,结果表明：“国家公祭日”保障期间OC、EC的平均质量浓度为9.6 μg/m³和3.9 μg/m³,两者占PM_2.5质量的19%,是PM_2.5的重要组成部分;“国家公祭日”期间OC/EC（质量浓度比）的平均值为2.47,表明大气中存在二次反应生成的SOC,通过分析管控不同阶段EC与OC以及EC与SO₂、NO₂的相关性,表明两者受本地机动车影响较大;通过气流后向轨迹聚类分析表明,“国家公祭日”管控期间来自周边安徽、江苏、浙江交界处的气流对应的EC浓度最高,为7.14 μg/m³,进一步运用浓度权重轨迹（CWT）方法分析EC的潜在贡献源区,表明对南京EC输送强潜在源区主要在安徽省东南部,集中在芜湖、宣城、黄山一线,其贡献可超过8 μg/m³。     

场地地震反应的特征线解与等效线性化解对比研究∗

研究了响蹚(Ⅱ类)、盐城(Ⅳ类)、CHBH06(Ⅲ类)3种不同类别的场地在地震动作用下特征线差分计算结果与等效线性化法计算结果的差异性.在响蹬场地(Ⅱ类)下,随输入地震动峰值增加,特征线法计算的峰值加速度逐渐增加,反应谱曲线规律性递增;等效法计算峰值加速度先减小后增加,反应谱曲线在较大输入时逐渐递增.在盐城场地(Ⅳ类)下,特征线法计算的峰值加速度均比等效法的计算值稍大,反应谱平台宽度较等效法反应谱平台宽度宽.在KIK-net的CHBH06场地(Ⅲ类)中,将两种方法的计算结果与实际记录对比,结果表明:特征线法时程的傅里叶谱频带宽度与实际记录接近,加速度反应谱与实际记录的加速度反应谱较等效法加速度反应谱接近.通过对比分析,以期促进特征线差分方法的应用.     

Two comparative approaches to identify the conservation priority areas impacted by heavy metals on Yellow Sea coasts

This study aimed to develop a practical approach to identify the priority areas with ecological significance along highly human disturbed coastal areas. Field surveys were used to assess and complement to the results of the remote sensing (RS)-based analysis. The RS-based biodiversity hotspot (BH) identification process was accomplished in three steps. The lands with native vegetation cover, including the national natural reserve lands, were first selected as the baseline BHs (BBHs). Then, after assigning resistance coefficients to each land use, the least accumulative cost (LAC) of the BBHs was calculated by distance analysis, while the normalized differential vegetation index (NDVI) from the Landsat Thematic Mapper was reclassified into 20 grades based on the Euclidean distance to the main anthropogenic sources. Finally, the RS-based BH identification was realized through the logistic calculation of LAC less than a series of thresholds and NDVI more than 10. While the field survey-based BH identification was through the logistic calculation between HM potential ecological risks of low to moderate and BHs acquired by NDVI-based integrated assessments. The results proved that RS-based analysis could be an important surrogate for necessary field surveys to manage BHs along coasts.     

基于PCT方法的京津冀冬季PM2.5重污染天气型分析

T模态斜交主成分分析法（PCT）分析的天气过程时间尺度越长,该算法的优势越明显,天气分型结果也更完整,可信度越高.利用京津冀地区2014年冬季-2019年冬季（每年12月-翌年2月）的环境监测资料,以区域平均PM_2.5日均值大于150 μg·m^-3为标准,筛选出72个京津冀地区PM_2.5重污染日,采用ERA5提供的0.25°×0.25°气象再分析资料,应用PCT算法将72个PM_2.5重污染日海平面气压场客观地分为高压前部型、锋前低压型、高压后部型、均压场型和弱低压型5种类型,分别占总PM_2.5重污染天数的34.72%、20.83%、16.67%、16.67%和11.11%.另外,对2017年2月12-16日京津冀地区PM_2.5重污染过程的分析表明,重污染天气过程中随着逐日天气型的演变,污染物浓度特征、近地面风场和大气污染物污染传输路径均发生相应变化.