多种色谱质谱联用技术测定沉积物中的十溴二苯醚

随着十溴二苯醚(BDE-209)正式进入《斯德哥尔摩公约》名单,准确测量其浓度水平对研究其环境行为具有重要意义.本文对多种色谱质谱联用技术——气相色谱-负化学电离质谱(GC-NCI-MS)、气相色谱-电子轰击电离质谱(GC-EI-MS)、气相色谱-电感耦合等离子体质谱(GC-ICP-MS)和高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)进行了优化和评估,并对其在实际环境沉积物样品中检测BDE-209的性能进行了考察.4种检测方法的定量限为3—200 ng·mL^-1,在0.5-10μg·mL^-1的范围内有良好的线性关系(r^2>0.995),测量结果的相对标准偏差(RSD)在0.5%—8.7%之间,可以满足BDE-209分析检测的需求.应用到沉积物实际样品的检测时,各方法测量结果的RSD为0.7%—15.7%,基质效应为98%—166%,其中GC-EI-MS和GC-NCI-MS表现出基质增强效应且分析结果的稳定性受到影响,可通过内标或基质加标方式进行校正,GC-ICP-MS、HPLC-ICP-MS几乎不受实际样品基质的影响,测量结果的准确性良好.

基于实际道路测试的大型客车排放特征研究

应用车载排放测试系统(PEMS)对天津市4辆大型客车(国Ⅲ、国Ⅳ、国Ⅴ柴油车和国Ⅴ液化天然气车)进行了实际道路尾气排放测试。结果表明,3辆柴油车CO、NOx、总碳氢化合物(THC)和颗粒物(PM)的平均排放因子分别为3.435、6.431、0.131、0.324g/km,天然气车CO、NOx、THC和PM的排放因子分别为1.240、17.451、6.535、0.003g/km。总体看来,3辆柴油车的污染物排放速率随着排放标准的提高而降低,与其相比,天然气车的CO和PM排放速率相对较低,而NOx和THC排放速率较高;4辆大型客车各污染物排放速率在加速工况下排放速率最高,怠速工况下排放速率最低。随着国Ⅳ柴油车行驶速度从0~<20km/h提高到80~<100km/h,尾气温度逐渐上升,选择性催化还原装置对NOx的削减率可从41.8%升高到64.5%。

Evaluation on Salt Tolerance of 25 Species of Poplar Cuttings in Lab

The growth and morphological characteristics of 25 species of poplar were investigated. The cuttings were cultivated in Hoagland Nutrient Solution, which was made with sodium chloride (NaCl) solutions of concentration of 1.00, 3.00, 4.00, 5.00, 6.00, and 8.00 g/L, respectively. Under such salt stress, the new branch length and biomass accumulation of cuttings decreased as the salt concentration increased. The root/shoot ratio of most of species showed an escalation and then reduction tendency. Under low concentration of salt (NaCl ≤4.00 g/L), the root/shoot ratio of 11 species increased, compared to NaCl =1.00 g/L. After salt treatments, with the increase of salinity concentration, the content of chlorophyll of 8 species decreased. Based on the analysis of growth and morphological appearance, it turned out that 6 species had high salt-tolerant, 7 species were moderate salt-tolerant, 7 species were low salt-tolerant and 5 species failed to resist salt stress.