成都颗粒物吸湿增长特征及订正方法研究

利用2013年6月—2014年5月成都市人民南路四段逐时PM_(2.5)质量浓度、大气能见度监测资料及同期温江站相对湿度观测数据,分析了该区域相对湿度对大气消光系数的影响,探讨了消光系数湿度订正方法的原理和技术流程.结果表明:针对细颗粒物而言,平均单位质量“湿”消光系数在相对湿度为40%时存在突变(通过了α=0.05的信度检验),当相对湿度小于40%时,平均单位质量“湿”消光系数呈现平稳波动的特征;而当相对湿度介于40%~90%时,平均单位质量“湿”消光系数增长趋势明显;现有的湿度订正方法未能在成都地区起到相应的订正效果;单位质量“湿”消光系数直观上表现为非平稳随机序列,基于单位质量“湿”消光系数和单位质量“干”消光系数在统计意义下应具有一致性的原则,从不确定性分析的角度提出了消光系数湿度订正的新方法,取得了令人满意的结果.     

芳香烃含量对直喷汽油机颗粒物排放影响的试验研究

在一台增压中冷缸内直喷(GDI)汽油机上,开展了不同芳香烃含量的汽油对发动机颗粒物粒径分布和数量浓度影响的研究.结果表明,在正常热机工况下,随着负荷增加,核态颗粒物增加明显,颗粒物排放逐渐由三峰分布演变为双峰分布,并且芳烃含量高时,颗粒物排放明显增多.冷机工况及冷怠速时,芳烃含量对颗粒物的排放影响较小.和冷怠速相比,热怠速时颗粒物向小粒径方向移动,且颗粒物数量减少.热怠速时高芳烃含量的汽油排气中颗粒物相对较多.不同芳烃含量下,发动机参数对颗粒物排放会有一定影响,重芳烃含量高的汽油其颗粒物排放也高.     

Quantifying the characteristics of particulate matters captured by urban plants using an automatic approach

It is widely accepted that urban plant leaves can capture airborne particles. Previous studies on the particle capture capacity of plant leaves have mostly focused on particle mass and/or size distribution. Fewer studies, however, have examined the particle density, and the size and shape characteristics of particles, which may have important implications for evaluating the particle capture efficiency of plants, and identifying the particle sources. In addition, the role of different vegetation types is as yet unclear. Here, we chose three species of different vegetation types, and firstly applied an object-based classification approach to automatically identify the particles from scanning electron microscope(SEM)micrographs. We then quantified the particle capture efficiency, and the major sources of particles were identified. We found(1) Rosa xanthina Lindl(shrub species) had greater retention efficiency than Broussonetia papyrifera(broadleaf species) and Pinus bungeana Zucc.(coniferous species), in terms of particle number and particle area cover.(2) 97.9% of the identified particles had diameter ≤10 μm, and 67.1% of them had diameter ≤2.5 μm. 89.8% of the particles had smooth boundaries, with 23.4% of them being nearly spherical.(3) 32.4%–74.1% of the particles were generated from bare soil and construction activities, and 15.5%–23.0% were mainly from vehicle exhaust and cooking fumes.     

Distribution and mode of occurrence of uranium in bottom ash derived from high-germanium coals

The radioactivity of uranium in radioactive coal bottom ash(CBA) may be a potential danger to the ambient environment and human health. Concerning the limited research on the distribution and mode of occurrence of uranium in CBA, we herein report our investigations into this topic using a number of techniques including a five-step Tessier sequential extraction, hydrogen fluoride(HF) leaching, Siroquant(Rietveld) quantification, magnetic separation, and electron probe microanalysis(EPMA). The Tessier sequential extraction showed that the uranium in the residual and Fe–Mn oxide fractions was dominant(59.1%and 34.9%, respectively). The former was mainly incorporated into aluminosilicates,retained with glass and cristobalite, whereas the latter was especially enriched in the magnetic fraction, of which about 50% was present with magnetite(Fe_3O_4) and the rest in other iron oxides. In addition, the uranium in the magnetic fraction was 2.6 times that in the non-magnetic fraction. The experimental findings in this work may be important for establishing an effective strategy to reduce radioactivity from CBA for the protection of our local environment.     

Efficient removal of naphthalene-2-ol from aqueous solutions by solvent extraction

Naphthalene-2-ol is a typical biologically recalcitrant pollutant in dye wastewater.Solvent extraction of naphthalene-2-ol from aqueous solutions using mixed solvents was investigated.Various extractants and diluents were evaluated,and the effects of volume ratio of extractant to diluent,initial p H,initial concentration of naphthalene-2-ol in aqueous solution,extraction time,temperature,volume ratio of organic phase to aqueous phase(O/A),stirring rate and extraction stages,on extraction efficiency were examined separately.Regeneration and reuse of the spent extractant were also investigated.Results showed that tributyl phosphate(TBP) achieved 98% extraction efficiency for naphthalene-2-ol in a single stage extraction,the highest among the 12 extractants evaluated.Extraction efficiency was optimized when cyclohexane and n-octane were used as diluents.The solvent combination of 20% TBP,20% n-octanol and 60% cyclohexane(V/V) obtained the maximum extraction efficiency for naphthalene-2-ol,99.3%,within 20 min using three cross-current extraction stages under the following extraction conditions:O/A ratio of 1:1,initial p H of 3,25°C and stirring rate of 150 r/min.Recovery of mixed solvents was achieved by using 15%(W/W) Na OH solution at an O:A ratio of 1:1 and a contact time of 15 min.The mixed solvents achieved an extraction capacity for naphthalene-2-ol stably higher than90% during five cycles after regeneration.     

天津市近海海域人工鱼礁选址适宜性评价

鱼礁选址是人工鱼礁建设首要考虑的重要环节,科学评价分析是确保人工鱼礁建设成功的前提。本文依据影响鱼礁选址的主要因素,从海洋功能区划、海洋物理化学环境、海洋生物资源环境三方面选取了海洋功能区、水深、流速、水质、底质类型、生物资源、重要渔业水域等7项指标,运用ArcGIS技术手段,对天津市近海海域人工鱼礁投放的适宜性进行了评价,得出最适宜、较适宜及一般适宜人工鱼礁布设区域的空间分布,这三类区域所占面积分别为8.61 km2、29.78 km2和38.02 km2,其中,最适宜鱼礁投放的区域位于汉沽区营城镇蔡家堡村至大神堂村以南水深4~5 m的海域,与天津市目前已开展的人工鱼礁投礁区域相距较近;较适宜开展鱼礁投放的区域主要分布在太平镇沙井子乡以东水深9~10 m的海域及最适宜区的外围区域。实证研究结果可为天津市人工鱼礁建设提供技术支撑和参考依据,同时也为我国人工鱼礁建设适宜性评价提供借鉴。     

浒苔衰亡过程中营养盐的释放过程及规律

为探究浒苔衰亡过程中营养盐的释放规律,在实验室内模拟浒苔衰退过程中主要营养盐氮、磷的释放过程。结果表明:浒苔藻体重量和叶绿素含量分别呈现下降趋势,第12 d时,漂浮浒苔和培养浒苔的藻体重量分别下降到0.46 g和0.79 g,叶绿素含量分别下降到0.64 mg/g和0.99 mg/g。实验组水体中的磷和总无机氮（DIN）浓度均呈现先下降后上升的趋势,漂浮浒苔实验组的磷和DIN浓度增加量高于培养浒苔实验组,到第12 d时,漂浮浒苔实验组的磷和DIN浓度分别达到3.95 μmol/L和76.55 μmol/L。从第6 d开始漂浮浒苔向水体中大量释放NH₄-N,使得总无机氮浓度迅速升高。大量聚集漂浮浒苔的衰亡会引起水体缺氧,并释放大量的营养盐,导致水体的恶化,因此必须及时的清理海面聚集的漂浮浒苔。     

赤泥强化型河岸带模拟系统对再生水中磷去除效果的研究

为了探讨不同比例赤泥施入量对再生水磷去除效果的影响以及植物在再生水净化过程的作用,利用赤泥中富含钙、铁、铝等金属氧化物对磷具有较强吸附性能的特点,构建了室内赤泥强化型河岸带模拟系统.结果表明,赤泥最适施入质量分数为2.5%～5.0%,此时TP去除率为82%～76%,出水磷浓度约为0.22～0.29 mg/L,SRP/TP比值为74%～75%.当赤泥施入量为2.5%时,相比无植物系统,有植物系统的磷净化效率提高了4%,约为86%,出水磷浓度为0.17mg/L.这些结果表明赤泥可以适当比例直接掺混于河岸带的土壤中,这为其提高对再生水中磷的去除能力提供了一种新途径.     

自组装纳米金修饰玻碳电极检测亚硝酸根

将N-［3-(三甲氧硅基)丙基］-乙二胺与金溶胶通过自组装制备亚硝酸根的电化学传感器.原子力显微镜图(AFM) 显示纳米金自组装在氨基硅烷修饰的玻碳电极表面.由于质子化的氨基硅烷与带负电的亚硝酸根间的相互作用以及纳米金对亚硝酸根具有较好的催化作用,亚硝酸根在该修饰电极上的氧化电位与在玻碳电极上的氧化电位相比负移了140 mV.利用微分脉冲伏安法和微分脉冲安培法研究了亚硝酸根电流响应信号与浓度间的关系.在最优实验条件下,亚硝酸根的氧化峰电流与其浓度在5.0×10^-7～1.0×10^-3 mol·L^-1的浓度范围内呈良好的线性关系, 检测限可达到2.0×10^-7 mol·L^-1(信噪比为3). 用分光光度法及本研究提出的方法对实际样品中亚硝酸根的测定进行了比较,测定结果的差异很小.本研究所提出的测定亚硝酸根的方法具有较高的灵敏度和较好的重现性.     

胜利油田区水体中环境雌激素生态风险评估

为了评价胜利油田石油开采对水体中雌激素生态风险。首先,检测胜利油田区26个样品中盐度、总氮、总磷、余氯、COD、石油烃类物质含量6个常规水质指标,结果发现水体中总氮及COD的含量均值达到5.2mg/L及64mg/L,这表明该区域有机污染物及富营养化程度比较严重。其次,利用人雌激素受体基因酵母干粉法检测了样品中环境雌激素含量,结果分析发现不同采样点间的雌激素污染水平不同,雌激素含量与水质指标间无显著相关性。样品中雌激素含量范围0.046-0.072ng/L,均值为0.062ng/L,雌激素水平相对较低,这证实胜利油田水体存在环境雌激素生态风险值也较低。