基于10辆轻型汽油车的实际行驶与台架工况排放特征及影响因素研究

利用便携式排放测试系统（Portable emission measurement system, PEMS）分析了10辆轻型汽油车分别在实验室台架和实际行驶排放（Real driving emission, RDE）工况下典型空气污染物的排放特征和影响因素.测试结果表明,轻型汽油车在冷启动和热启动阶段产生的一氧化碳（CO）、碳氢化合物（HC）、氮氧化物（NO_x）分别是热运行1阶段和热运行2阶段的28.0、 32.9、 28.4倍和4.0、 11.2、 5.4倍,表明车辆启动对机动车排放贡献显著.台架工况排放因子受车辆启动排放影响较大,在台架实验去除启动排放影响的情况下,台架CO₂、CO、HC和NO_x排放因子将分别减小2.3%±1.3%、44.2%±30.6%、47.5%±29.6%和44.9%±30.8%.在相同速度下,RDE工况下的CO₂排放因子相比不考虑启动排放的台架工况排放因子要高出31.7%±5.0%.单车瞬态排放数据分析结果表明,RDE测试相比于台架工况测试覆盖了更多的机动车行驶工况特征,可以更准确地量化车辆在实际道路行驶过程中不同工况下的排放特征.因此,开展RDE排放测试对于准确量化机动车尾气排放特征,尤其是对 建立微观尺度机动车排放清单支撑城市精细化管控具有重要意义.     

How well does XAD resin extraction recover halogenated disinfection byproducts for comprehensive identification and toxicity testing?

Halogenated disinfection byproducts (DBPs) are an unintended consequence of drinking water disinfection, and can have significant toxicity. XAD resins are commonly used to extract and enrich trace levels of DBPs for comprehensive, nontarget identification of DBPs and also for in vitro toxicity studies. However, XAD resin recoveries for complete classes of halogenated DBPs have not been evaluated, particularly for low, environmentally relevant levels (ng/L to low µg/L). Thus, it is not known whether levels of DBPs or the toxicity of drinking water might be underestimated. In this study, DAX-8/XAD-2 layered resins were evaluated, considering both adsorption and elution from the resins, for extracting 66 DBPs from water. Results demonstrate that among the 7 classes of DBPs investigated, trihalomethanes (THMs), including iodo-THMs, were the most efficiently adsorbed, with recovery of most THMs ranging from 50%-96%, followed by halonitromethanes (40%-90%). The adsorption ability of XAD resins for haloacetonitriles, haloacetamides, and haloacetaldehydes was highly dependent on the individual species. The adsorption capacity of XAD resins for haloacetic acids was lower (5%-48%), even after adjusting to pH 1 before extraction. Recovery efficiency for most DBPs was comparable with their adsorption, as most were eluted effectively from XAD resins by ethyl acetate. DBP polarity and molecular weight were the two most important factors that determine their recovery. Recovery of trichloromethane, iodoacetic acid, chloro- and iodo-acetonitrile, and chloroacetamide were among the lowest, which could lead to underestimation of toxicity, particularly for iodoacetic acid and iodo-acetonitrile, which are highly toxic.     

Source profile and health risk assessment of PM2.5 from coal-fired power plants in Fuxin,China

In order to improve and establish the localized source profile of PM_2.5 in Fuxin, the ashes under dust catcher were collected from four typical coal-fired power plants in Fuxin and twenty-eight components were measured. The source profile of PM_2.5 in the soot of the four coal-fired power plants was established. SO₄^2? was the most abundant component in the PM_2.5 of the soot of the four coal-fired power plants, followed by Ca²⁺ and organic carbon (OC). The content of element components in PM_2.5 smoke ranges from 5.06 to 10.97%, the content of ionic components ranges from 36.53 to 48.59%, and the total carbon content ranges from 9.43 to 11.36%. The divergence coefficient of PM_2.5 source profile in Fuxin coal burning smoke is mostly similar to that of Fushun, whereas the divergence coefficient of Colorado reaches 0.65, indicating that Fuxin coal burning power plant smoke has no similarity to Colorado. The order of the geological accumulation index of Ni, Cu, V, Mn, and Cr was Cr (4.58) > Mn (4.42) > V (4.38) > Cu (4.09) > Ni (4.06), showing a heavy pollution level. The health risk assessment model recommended by the USEPA was used to assess the health risk of heavy metals in soot of coal-fired power plants, and the non-carcinogenic risk values of As for children and adults were 45.7 and 4.90, respectively. The carcinogenic risk values of Cr for adults and children were the highest, with values of 3.66 × 10^?5 and 2.06 × 10^?5, respectively, followed by As.

     

基于GIS的中国城市水环境管理研究现状与趋势分析

随着中国城市规模迅速扩大、人口急剧增加,给城市水环境造成了巨大压力.由于绝大多数水环境信息是与空间位置关系密不可分的,在使用传统管理信息系统以及数据统计方式处理大量的水环境数据时,并不能很好地利用与呈现空间特征,因此,具有地理空间分析功能的地理信息系统（GIS）逐渐受到重视.然而,目前GIS在城市水环境管理中仍存在需要思考和改善的地方,以形成完整的城市水环境决策系统,提出可用的环境改善建议.     

利用正交试验法优化原子吸收测定镉的仪器参数研究

镉对人类和动物是一种毒性极强的污染物,由于工业化发展和人类活动范围扩大,导致环境镉污染越来越严重.环境监测站用火焰原子吸收光谱法测定镉,但影响镉准确测定的因素较多.为了优化原子吸收测定镉的仪器参数,利用正交试验法,对原子吸收分析过程中需要设置的原素灯工作电流、燃气流量和燃烧器高度三个主要因素进行无交互作用试验,优化仪器参数：原素灯工作电流4mA、燃气流量1 200 ml/min、燃烧器高度5.0 mm,其中燃气流量影响最显著.     

论北京市生活垃圾产业化的必要性及可行性

本文主要结合北京市生活垃圾现状分析了实施垃圾产业化的必要性及可行性,并为产业化的实施提出了建议。     

Characterization of particulate products for aging of ethylbenzene secondary organic aerosol in the presence of ammonium sulfate seed aerosol

Aging of secondary organic aerosol(SOA) particles formed from OH– initiated oxidation of ethylbenzene in the presence of high mass(100–300 μg/m~3) concentrations of(NH_4)_2SO_4seed aerosol was investigated in a home-made smog chamber in this study.The chemical composition of aged ethylbenzene SOA particles was measured using an aerosol laser time-of-flight mass spectrometer(ALTOFMS) coupled with a Fuzzy C-Means(FCM) clustering algorithm.Experimental results showed that nitrophenol,ethyl-nitrophenol,2,4-dinitrophenol,methyl glyoxylic acid,5-ethyl-6-oxo-2,4-hexadienoic acid,2-ethyl-2,4-hexadiendioic acid,2,3-dihydroxy-5-ethyl-6-oxo-4-hexenoic acid,1H-imidazole,hydrated N-glyoxal substituted1H-imidazole,hydrated glyoxal dimer substituted imidazole,1H-imidazole-2-carbaldehyde,N-glyoxal substituted hydrated 1H-imidazole-2-carbaldehyde and high-molecular-weight(HMW) components were the predominant products in the aged particles.Compared to the previous aromatic SOA aging studies,imidazole compounds,which can absorb solar radiation effectively,were newly detected in aged ethylbenzene SOA in the presence of high concentrations of(NH_4)_2SO_4seed aerosol.These findings provide new information for discussing aromatic SOA aging mechanisms.     

机械制造厂综合废水处理工艺

提出了机械制造综合废水污染处理方案。为了减少投资,减少总占地面积和降低运行成本,将涂装废水、机加工切削废液、饭堂的生活污水等混合起来进行集中综合处理。为了确定最佳的处理方案,进行了预处理工艺试验,取得了一系列的试验数据,并将这些结果和生化处理经验,应用于机械制造厂的废水处理,取得良好效果。     

含酸性添加剂的细水雾洗消氨气的性能研究

为提高细水雾对氨气的洗消效率,研究了两种复合型酸性添加剂MZ—1和MZ-2对细水雾的物理化学性质及洗消性能的影响。采用三维激光多普勒测速计和自适应相位多普勒速度计系统（LDV／APV）测量了含有MZ添加剂的细水雾和纯细水雾的雾滴粒径及速度的变化。通过小尺度模拟实验比较了含添加剂的细水雾和纯细水雾洗消氨气的效能高低。对实验结果的分析表明洗消剂中各成分之间的物理化学耦合作用提高了细水雾的洗消效率：表面活性剂组分降低了溶液的表面张力,减小了雾滴粒径,增大了细水雾与氨气的接触面积,而酸性电解质组分则可以与氨气发生化学反应,增强洗消剂的化学洗消作用。     

Changes in distribution patterns of weed species richness in agricultural lands on Qinghai-Tibet Plateau under climate change北大核心CSCD

农田杂草是阻碍农业生产的主要因素之一.明确农田杂草丰富度分布格局对农业生产管理具有重要意义.以青藏高原农田杂草为研究对象,利用物种分布模型探讨基于县域尺度的农田杂草物种丰富度分布格局及其未来(2050s)的变化,利用逐步回归筛选影响物种丰富度的环境因子,基于传统最小二乘法(OLS)和地理加权回归模型(GWR)分析环境因子对农田杂草物种丰富度的影响,并对两种分析方法进行比较.结果显示:(1)分布在青藏高原的农田主要杂草有51科284种,其中59种单子叶杂草、222种双子叶杂草、135种一年生杂草和149种多年生杂草.青藏高原农田杂草物种丰富度呈由西向东递增的变化规律,物种丰富度中心(丰富度值为167-194)主要集中在一江两河、河湟谷地和川西北等地区;(2)全球气候变化背景下,未来(2050s)青藏高原农田杂草物种丰富度整体呈由东南向西北方向增加的趋势,其中SSP1-2.6情境下最多增加43种,SSP5-8.5情境下最多增加49种;(3)GWR模型优于OLS,其结果表明青藏高原农田杂草物种丰富度的主要驱动因子是最冷季平均温、太阳辐射和最干月降水量,上述变量对杂草丰富度的影响存在明显的空间差异性,其中最冷季平均温由南向北逐渐从负向影响转变为正向影响.太阳辐射整体在青藏高原东部边缘等地区对农田杂草丰富度起正向的影响,在藏东南、青藏高原北部边缘等地区起负向的影响.最干月降水量对整个研究区域起负向影响,并表现出影响力由南向北逐步递增的趋势.上述结果表明青藏高原农田杂草物种丰富度调查不足,实际观测到的丰富度值明显低于当前气候下潜在的丰富度值,存在低估现象.当前气候背景下的农田杂草物种丰富度中心分布地区在未来仍是重点监管对象,且未来青藏高原部分地区作物可能面临新的杂草入侵风险.建议未来研究应注重于青藏高原粮食主产区农田杂草群落结构和功能调查、杂草和作物种间关系、耕地尺度上丰富度驱动因子分析等方面,为区域杂草管理和防治提供充分科学依据.(图6表2参53)