标准气溶胶发生系统的建立与性能评估

针对气溶胶测量仪器校准和实验室气溶胶光学特性研究的需求,搭建了一套标准气溶胶发生系统,并对其性能开展了测试研究.系统采用恒定流量的雾化器产生气溶胶,经过扩散干燥管干燥以及电荷中和器带电中和后,产生标准气溶胶粒子.利用氯化钠样品对系统的性能进行了测试,结果表明,当样品溶液浓度增加时,系统雾化产生粒子的数浓度和粒径均随之增加;当载气气压增加,系统雾化产生粒子的数浓度随之增加,而粒径随之减小.在测试时间内,系统发生的多分散气溶胶粒子的几何平均粒径波动小于1%,总粒子数浓度波动小于2%,单分散气溶胶粒子数浓度的稳定性好于4%.     

北京地区不同时段平均PM2.5浓度与MODIS气溶胶光学厚度相关性分析

利用2014年北京市12个空气质量监测站的逐小时PM_(2.5)地面观测资料,以及Terra和Aqua卫星的MODIS气溶胶光学厚度(AOD)产品,在时间和空间数据匹配的基础上,研究了PM_(2.5)的5 h(10:00—14:00)和24 h(0:00—23:00)两种时段平均浓度及两颗卫星平均AOD的时空分布特征,并建立了AOD与不同时段平均PM_(2.5)浓度之间的回归模型.结果表明:PM_(2.5)的5 h平均浓度和24 h平均浓度值均在城区高、郊区低,最低值位于定陵站;匹配后逐时PM_(2.5)浓度的日变化呈"双峰型",最低值出现在下午,但北京西北部郊区的定陵和昌平镇站因局地山谷风环流和外部排放源的影响,其"双峰型"波动趋势较城区站偏弱,最低值出现在上午;AOD的空间分布特征与PM_(2.5)浓度分布一致,但在郊区由于污染水平分布不均,卫星采集的样本可能来自于周围的清洁大气,导致AOD的最小值在郊区站点明显低于城区站点;两颗卫星平均的AOD与5h PM_(2.5)平均浓度的决定系数高于AOD与24 h PM_(2.5)平均浓度的决定系数;AOD与PM_(2.5)的相关系数在城区高于郊区,郊区排放源分布不均和强的局地系统性环流是造成其相关系数低的重要原因.     

乌鲁木齐市MODIS气溶胶光学厚度与PM10浓度关系模型研究

为了建立乌鲁木齐市近地面PM10浓度监测的关系模型,利用乌鲁木齐市2013年3—11月、2014年3—11月MODIS AOD产品与同期地面观测的PM10质量浓度进行相关分析,结果表明二者直接相关程度较低(r=0.433,p0.01);然后以WRF模式模拟的大气边界层高度及地面观测的相对湿度数据对AOD进行垂直、湿度订正后,二者相关性得到较大程度提高(r=0.630,p0.01);按照季节分类统计和订正春、夏、秋季的相关系数r分别为0.779、0.393、0.523,均大于统计学上99%的置信度要求,其中春季的订正最为有效,可用性更高;最后,建立全年和各季AOD-PM10最优拟合模型并反演乌鲁木齐市地面PM10质量浓度,全年和三季的反演结果与实测数据的相关系数分别为0.757、0.748、0.652、0.715(p0.01);同时基于卫星遥感AOD反演得到的PM10质量浓度的空间分布与AOD呈现出整体的一致性,并且3个季节AOD平均值表现为:春季秋季夏季.证实了卫星遥感AOD经过垂直和湿度订正后,可以作为辅助监测乌鲁木齐市PM10地面浓度分布的一个有效手段.     

A Contemporary Assessment of Change in Humid Tropical Forests

Abstract: In recent decades the rate and geographic extent of land‐use and land‐cover change has increased throughout the world's humid tropical forests. The pan‐tropical geography of forest change is a challenge to assess, and improved estimates of the human footprint in the tropics are critical to understanding potential changes in biodiversity. We combined recently published and new satellite observations, along with images from Google Earth and a literature review, to estimate the contemporary global extent of deforestation, selective logging, and secondary regrowth in humid tropical forests. Roughly 1.4% of the biome was deforested between 2000 and 2005. As of 2005, about half of the humid tropical forest biome contained 50% or less tree cover. Although not directly comparable to deforestation, geographic estimates of selective logging indicate that at least 20% of the humid tropical forest biome was undergoing some level of timber harvesting between 2000 and 2005. Forest recovery estimates are even less certain, but a compilation of available reports suggests that at least 1.2% of the humid tropical forest biome was in some stage of long‐term secondary regrowth in 2000. Nearly 70% of the regrowth reports indicate forest regeneration in hilly, upland, and mountainous environments considered marginal for large‐scale agriculture and ranching. Our estimates of the human footprint are conservative because they do not resolve very small‐scale deforestation, low‐intensity logging, and unreported secondary regrowth, nor do they incorporate other impacts on tropical forest ecosystems, such as fire and hunting. Our results highlight the enormous geographic extent of forest change throughout the humid tropics and the considerable limitations of the science and technology available for such a synthesis.     

混合基质3D打印可见光催化系统对病毒气溶胶的去除

利用3D打印灵活可控的特点和复合材料混合打印的优势，将可见光响应的ZnO/g-C₃N₄催化剂掺入ABS塑料，利用3D打印制成催化剂均匀稳定分布的光催化系统，使用流体动力学仿真模拟对反应器结构进行优化设计，用于处理相对密闭的室内空间中的病毒气溶胶.结果表明，病毒气溶胶比细菌气溶胶具有更强的抗逆性，添加螺旋导流板可以显著提升反应器传质性能并有效改善系统光催化效果，以提高对病毒气溶胶的去除率.以商业LED灯为光源的螺旋式反应器对高浓度病毒气溶胶（MS2、PhiX174噬菌体）和细菌气溶胶（大肠杆菌）具有高效去除效果，在3.75min停留时间可以实现对气溶胶的完全去除.     

云南磷石膏综合利用现状及次生环境问题

调查了云南磷石膏的特性和磷石膏的综合利用现状,分析了云南磷石膏目前的综合利用技术情况,探讨了综合利用过程中存在的次生环境问题,并从技术和管理的角度提出了对策建议。     

超声雾化法捕集气溶胶的试验研究

核设施退役过程,放射性气溶胶浓度较高,需要进行处理,以降低工作人员辐照风险。研究捕集剂配方、雾化通入量等对模拟气溶胶捕集效果的影响,结果表明:捕集剂配方对气溶胶捕集的效果差异明显;粒径越小的气溶胶粒子被雾化捕集的速度较慢;捕集剂通入量在0.06 kg/m3以下,对气溶胶捕集效果影响显著。对等离子切割解体设备产生的241Am、239Pu污染气溶胶进行雾化捕集,初始污染水平为136 Bq/m3的气溶胶经雾化捕集后可降至1.23 Bq/m3,捕集的效果显著。     

Acid-catalyzed heterogeneous reaction of 3-methyl-2-buten-1-ol with hydrogen peroxide

Acid-catalyzed heterogeneous oxidation with hydrogen peroxide(H2O2) has been suggested to be a potential pathway for secondary organic aerosol(SOA) formation from isoprene and its oxidation products. However, knowledge of the chemical mechanism and kinetics for this process is still incomplete. 3-Methyl-2-buten-1-ol(MBO321), an aliphatic alcohol structurally similar to isoprene, is emitted by pine forests and widely used in the manufacturing industries. Herein the uptake of MBO321 into H2SO4–H2O2mixed solution was investigated using a flow-tube reactor coupled to a mass spectrometer. The reactive uptake coefficients(γ) were acquired for the first time and were found to increase rapidly with increasing acid concentration. Corresponding aqueous-phase reactions were performed to further study the mechanism of this acid-catalyzed reaction. MBO321 could convert to 2-methyl-3-buten-2-ol(MBO232) and yield isoprene in acidic media. Organic hydroperoxides(ROOHs) were found to be generated through the acid-catalyzed route,which could undergo a rearrangement reaction and result in the formation of acetone and acetaldehyde. Organosulfates, which have been proposed to be SOA tracer compounds in the atmosphere, were also produced during the oxidation process. These results suggest that the heterogeneous acid-catalyzed reaction of MBO321 with H2O2 may contribute to SOA mass under certain atmospheric conditions.     

北仑区域大气中黑碳气溶胶特征研究

利用2012年－2014年在北仑城区的黒碳气溶胶及相关的能见度、SO2、NO2、CO、O3、PM1、PM2．5因子的监测结果,研究区域黒碳气溶胶的污染特征及与其他相关因子的关系等。结果表明,黒碳气溶胶随着浓度的不同组分会有所差异。另外,区域内的黒碳气溶胶的本底值为1.25μg／m3,在国内大城市中处于相对低位,但远高于全球本底值;黒碳气溶胶对消光的贡献为12．13％;与SO2等的相关性分析表明,其与PM2．5、PM 1、NO 2均为强正相关,与SO 2和CO均为中等强度正相关,而与O 3则显示了负的指数相关。     

化工园区水环境风险公共应急设施布局研究

重大事故状态下,单个化工企业的风险防控设施(应急池等)无法控制事故污水的情形下,整个化工园区的公共应急设施十分必要.在化工园区环境风险特征分析、突发事故次生水环境污染发生过程分析的基础上,提出建立整个化工园区的水环境风险三级防控体系,统一规划布局园区水环境风险公共应急设施,保障事故污水不出园区,根本上提高对事故污水的控制能力,最后以某临港化工园区进行案例分析.