南昌市PM2.5中铵盐及其气态前体物的分布特征与转化机制

在南昌市三种类型环境区域(混合区、道路区域以及郊区)开展PM_(2.5)中NH_4~+和空气中NH_3的同步采样监测,分析PM_(2.5)中铵盐及其气态前体物的分布特征,探讨氨气的转化与细粒子铵盐的形成机制,结果显示:2014-2015年采样期间南昌不同区域空气中NH_3浓度和PM_(2.5)中NH_4~+浓度较高;NH_3浓度存在空间分布差异,反映了不同环境区域NH_3源强的差异;NH_4~+浓度的空间分布表现为道路区域、郊区高于混合区,源于道路区域和郊区的气态前体物浓度高;NH_3/NH_4~+比值郊区道路区混合区,反映NH_4~+的形成受前体物(SO_2、NO_x)影响大;NH_3浓度春秋冬夏,说明NH_3源强受各季气象条件的影响大;NH_4~+浓度呈现秋冬高、春夏低的特征,反映不同季节的气象条件对铵盐的生成、清除和分解的影响不同;然而,NH_3/NH_4~+比值春夏秋冬,NH_3/NH_4~+比值季节分布与NH_4~+浓度季节分布呈相反的趋势;NH_3浓度昼、夜分布有差异,受昼夜间温差、太阳辐射、源强、逆温等多种因素的影响;NH_4~+浓度日变化各季节有差异;NH_3/NH_4~+比值日分布与NH_3浓度日分布相似;不同季节PM_(2.5)中铵盐形成的受控因素有差异,主要影响因素是气态前体物和温度、湿度;NH_4~+/SO_4~(2-)的比值(1.5),表明铵盐充足;铵盐形式主要为硫酸铵、硝酸铵,硫酸氢铵较少。     

Preparation, characterization and performance of poly(m-phenylene isophthalamide)/organically modified montmorillonite nanocomposite membranes in removal of perfluorooctane sulfonate

Nanocomposite membranes containing poly(m-phenylene isophthalamide) (PMIA) and organically modified montmorillonite (OMMT) were prepared by a combination of solution dispersion and wet-phase inversion methods, and the effects of OMMT addition on the properties and performance of fabricated nanofiltration membranes were investigated. The membranes were characterized by contact angle measurements, scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis, and zeta potential. The performance of the membranes was elucidated by the removal of perfluorooctane sulfonate (PFOS) at neutral pH. Increasing OMMT concentration improved the thermal stability and hydrophilicity of the membranes. The permeation and rejection of PFOS were significantly improved. The performance of fabricated nanofiltration membranes in removal of PFOS varied depending on the solute and membrane properties as well as solution conditions. Finally, a comparison between fabricated membranes and a commercial NF membrane (ESNA1-K1, Hydecanme) proved that the OMMT addition is a convenient procedure for producing nanocomposite membranes with superior properties and performance.     

Binding characteristics of Cu2+ to natural humic acid fractions sequentially extracted from the lake sediments

Humic acids (HAs) determine the distribution, toxicity, bioavailability, and ultimate fate of heavy metals in the environment. In this work, ten HA fractions (F1–F10) were used as adsorbent, which were sequentially extracted from natural sediments of Lake Wuliangsuhai, to investigate the binding characteristics of Cu²⁺ to HA. On the basis of the characterization results, differences were found between the ten extracted HA fractions responding to their elemental compositions and acidic functional groups. The characterization results reveal that the responses of ten extracted HA fractions to their elemental compositions and acidic functional groups were different. The O/C and (O + N)/C ratio of F1–F8 approximately ranged from 0.66 to 0.53 and from 0.72 to 0.61, respectively; the measured results showed that the contents of phenolic groups and carboxyl groups decreased from 4.46 to 2.60 mmol/g and 1.60 to 0.58 mmol/g, respectively. The binding characteristics of Cu²⁺ to the ten HA fractions were well modeled by the bi-Langmuir model; the binding behavior of Cu²⁺ to all the ten HA fractions were strongly impacted by pH and ionic strength. The FTIR and SEM-EDX image of HA fractions (pre- and post-adsorption) revealed that carboxyl and phenolic groups were responsible for the Cu²⁺ sorption on the ten sequentially extracted HA fractions process, which is the same with the analysis of the ligand binding and bi-Langmuir models Accordingly, the adsorption capacity of the former HA fractions on Cu²⁺ were higher than the latter ones, which may be attributed to the difference of carboxyl and phenolic group contents between the former and latter extracted HA fractions. Additionally, the functional groups with N and S should not be neglected. This work is hopeful to understand the environmental effect of humic substances, environmental geochemical behavior, and bioavailability of heavy metals in lakes.

     

金属离子对有机垃圾两相厌氧系统中UASB处理效果的促进作用

在"水解溶出 UASB反应器"处理城镇有机垃圾的两相厌氧系统中,向UASB反应器进水中添加K、Mg、Fe、Co、Ni 5种金属离子的组合促进剂,通过对UASB反应器容积负荷、产气量、产甲烷量在添加组合促进剂前后的比较,研究了组合促进剂(K、Mg、Fe、Co、Ni)对有机垃圾浸出液厌氧消化过程的促进作用.试验结果表明,添加组合促进剂后,反应器的平均容积负荷从12.89 kg COD/m3·d提高到17.79 kg COD/m3·d;平均污泥负荷从0.82 kg COD/kg VSS·d提高到1.07 kg COD/kg VSS·d.此外,平均每千克COD产气量为392.5 L,比添加组合促进剂之前增大了6.4%;而平均每千克COD产甲烷量为297.5 L,比添加组合促进剂之前增大了10.5%.对于氨氮、挥发性脂肪酸(VFA)、pH及碱度来说,在添加组合促进剂之后则无大的变化.     

浊度对混凝-纳滤组合工艺的影响

主要研究了不同浊度对混凝过程中的腐殖酸及高岭土去除率的影响。结果表明:随着高岭土投加浓度提高,混凝出水中腐殖酸去除率逐渐增大,而高岭土去除率降低;利用激光粒度仪对不同浊度条件下形成的絮体尺寸进行测定,结果表明:随着原水中高岭土投加浓度的增加,混凝出水形成的絮体尺寸逐渐增大,相应纳滤过程的出水通量得到明显改善;污染膜片的SEM显示,提高高岭土浓度在膜表面可形成更为疏松的滤饼层,并有效改善混凝出水的纳滤膜出水通量变化。     

云水和云下冲刷颗粒物与气态污染物对降水中硫酸盐和硝酸盐的贡献

为定量云水和云下冲刷分别对降水中SO₄2-、NO₃-的贡献,并进一步解析云下冲刷颗粒相和气相物质分别对降水样品中SO₄2-、NO₃-的贡献,于2016年4月-2017年2月采用APS-3A型降水自动采样仪对降水进行分段采集.采用离子色谱检测分段降水样品的ρ（SO₄2-）、ρ（NO₃-）,分析其变化规律;在降水前、降水中及降水后同步采集并检测大气颗粒相ρ（SO₄2-）、ρ（NO₃-）和气相ρ（SO₂）、ρ（NO₂）,分析颗粒相中ρ（SO₄2-）、ρ（NO₃-）和气相中ρ（SO₂）、ρ（NO₂）的变化与分布.结果表明:①ρ（SO₄2-）、ρ（NO₃-）在同一场降水的分段样品中呈逐渐降低至后期趋于平稳的趋势,说明降水对空气中污染物的冲刷使空气逐渐清洁,后期冲刷作用有限使得降水中离子质量浓度趋稳.②颗粒相中ρ（SO₄2-）、ρ（NO₃-）与气相中ρ（SO₂）、ρ（NO₂）在降水前较高,在降水中减小,并在降水后回升,说明降水对颗粒相SO₄2-、NO₃-和气相SO₂、NO₂均有清除作用,降水结束后无云下冲刷作用,污染物质量浓度逐步回升.③云水对降水中ρ（SO₄2-）、ρ（NO₃-）的贡献率分别为22%~56%（平均值为35%）、9%~49%（平均值为29%）,云下冲刷颗粒相SO₄2-、NO₃-对降水中ρ（SO₄2-）、ρ（NO₃-）的贡献率分别为39%~69%（平均值为55%）、43%~73%（平均值为56%）,云下冲刷气相SO₂、NO₂对降水中ρ（SO₄2-）、ρ（NO₃-）的贡献率分别为5%~17%（平均值为10%）、5%~19%（平均值为15%）.研究显示,降水中SO₄2-、NO₃-主要来源于云水和云下冲刷颗粒相SO₄2-、NO₃-,而来源于云下冲刷气相SO₂、NO₂较少.      

生物倍增(Bio-dopp)工艺处理城市污水

生物倍增工艺(Bio-dopp)是通过可防堵塞的曝气系统、生物除磷系统、空气提升系统及快速澄清装置,将生物硝化、反硝化,释磷、吸磷,有机物氧化等各工艺全部协调在同一反应池内同时进行,并在池内设立澄清区(相当于二沉池)的一种新型城市污水处理工艺。其高效曝气设备确保低氧条件下微生物去除耗氧有机物(特别是在同一反应器内实现硝化反硝化)。同时保证高效搅拌效果,并且工艺稳定,维护方便。它省去了传统工艺的污泥回流泵房、二沉池等构筑物及配电、管道等相应设备。具有出水稳定、设备高效,投资与运行成本低,占地面积小等优点,有较强竞争力。     

城市垃圾中转站选址优化模型的建立及其应用

为寻求一种城市垃圾中转站优化选址方法,根据城市垃圾收运系统的特点,引入逆向物流系统选址规划的理念,选用集合覆盖模型对中转站的位置进行初步优化,确定了垃圾中转站的待选点;在此基础上,运用整数规划构建整个城市垃圾收运系统费用现值最小模型,对城市垃圾中转站的初步规划进行二次优化,从待选点中选出垃圾中转站的最优组合,并计算出其分别接纳的垃圾量.通过实例分析,验证了城市垃圾中转站二次优化选址的可行性、实用性,可为垃圾收运系统的规划与设计提供参考依据.     

北京市水溶肥料重金属元素分析与评价

研究分析北京地区水溶肥料中的重金属元素,为农产品质量安全生产提供基础依据.对2012—2019年水溶肥料样品中Hg、As、Pb、Cr和Cd等有害元素进行调查统计,参照中国农业行业标准和内梅罗综合污染指数法进行分析与污染评价.结果表明,水溶肥料中Hg、As、Pb、Cr和Cd平均质量分数分别为0.04、3.8、3.9、4....     

Carbonaceous aerosol characteristics in outdoor and indoor environments of Nanchang, China, during summer 2009

A study of carbonaceous aerosol was initiated in Nanchang, a city in eastern China, for the first time. Daily and diurnal (daytime and nighttime) PM2.5 (particulate matter with aerodynamic diameter < or =2.5 microm) samples were collected at an outdoor site and in three different indoor environments (common office, special printing and copying office, and student dormitory) in a campus of Nanchang University during summer 2009 (5-20 June). Daily PM10 (particulate matter with aerodynamic diameter < or =10 microm) samples were collected only at the outdoor site, whereas PM2.5 samples were collected at both indoor and outdoor sites. Loaded PM2.5 and PM10 samples were analyzed for organic and elemental carbon (OC, EC) by thermal/optical reflectance following the Interagency Monitoring of Protected Visual Environments-Advanced (IMPROVE-A) protocol. Ambient mass concentrations of PM10 and PM2.5 in Nanchang were compared with the air quality standards in China and the United States, and revealed high air pollution levels in Nanchang. PM2.5 accounted for about 70% of PM10, but the ratio of OC and EC in PM2.5 to that in PM10 was higher than 80%, which indicated that OC and EC were mainly distributed in the fine particles. The variations of carbonaceous aerosol between daytime and nighttime indicated that OC was released and formed more rapidly in daytime than in nighttime. OC/EC ratios were used to quantify secondary organic carbon (SOC). The differences in SOC and SOC/OC between daytime and nighttime were useful in interpreting the secondary formation mechanism. The results of (1) OC and EC contributions to PM2.5 at indoor sites and the outdoor site; (2) indoor-outdoor correlation of OC and EC; (3) OC-EC correlation; and (4) relative contributions of indoor and outdoor sources to indoor carbonaceous aerosol indicated that OC indoor sources existed in indoor sites, with the highest OC emissions in I2 (the special printing and copying office), and that indoor EC originated from outdoor sources. The distributions of eight carbon fractions in emissions from the printer and copier showed obviously high OC1 (>20%) and OC2 (approximately 30%), and obviously low EC1-OP (a pyrolyzed carbon fraction) (<10%), when compared with other sources.