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981.
Shanzhi Xin Wei Gao Dandan Cao Kun Lv Yaquan Liu Chunyan Zhao Yawei Wang Guibin Jiang 《环境科学学报(英文版)》2019,31(1):378-387
The increasing production and usage of chlorinated paraffins(CPs) correspondently increase the amount of CPs that experience thermal processes. Our previous study revealed that a significant amount of medium-chain chlorinated paraffins(MCCPs), short-chain chlorinated paraffins(SCCPs) as well as aromatic and chlorinated polycyclic aromatic hydrocarbons(Cl-PAHs) were formed synergistically during the thermal decomposition of CP-52(a class of CP products).However, the transformation mechanisms of CP-52 to these compounds are still not very clear.This article presents a mechanistic analysis on the decomposition of CP-52 experimentally and theoretically. It was found that CP-52 initially undergoes dehydrochlorination and carbon chain cleavage and it transformed into chlorinated and unsaturated hydrocarbons. Cyclization and aromatization were the most accessible pathways at low temperatures(200–400°C), both of which produce mostly aromatic hydrocarbons. As the temperature exceeds 400°C, the hydrocarbons could decompose into small molecules, and the subsequent radical-induced reactions become the predominant pathways, leading to the formation of Cl-PAHs. The decomposition of CP-52 was investigated by using density functional theory and calculations demonstrating the feasibility and rationality of PCB and PCN formation from chlorobenzene. The results improve the understanding of the transformation processes from CP-52 to SCCPs and Cl-PAHs as well as provide data for reducing their emissions during thermal-related processes. 相似文献
982.
施肥对向日葵吸收积累Cd的影响 总被引:2,自引:4,他引:2
利用盆栽试验研究了不同施肥处理下(CK、N、NP、NPK) 3种向日葵品种(食用葵、观赏葵、油葵)对北方污染农田土壤镉(Cd)吸收和转运的影响.结果表明,施肥可显著提高观赏葵、油葵生物量及地上部Cd富集量,施NPK肥处理对植物促进效果最为显著.施NPK肥食用葵、观赏葵、油葵地上部Cd富集量分别可达6. 89、8. 92、6. 97 mg·kg~(-1),施肥处理显著提高了向日葵对Cd的富集能力,食用葵、观赏葵、油葵的富集系数(BCF)分别为2. 63(对照)~3. 10(NPK)、2. 80(对照)~4. 02(NPK)、2. 11(对照)~3. 14(NPK).对向日葵叶片亚细胞结构中Cd分布研究发现,将吸收的Cd富集在金属富集颗粒和细胞碎屑中是向日葵耐受Cd胁迫的主要解毒机制.综上所述,向日葵可作为Cd污染土壤的植物修复材料,合理施用NPK肥可明显提高植物对土壤Cd的修复效率. 相似文献
983.
Ji Hu Jianmin Wang Shuxia Liu Zhechao Zhang Haifeng Zhang Xiaoxia Cai Jianming Pan Jingjing Liu 《环境科学学报(英文版)》2018,30(4):208-215
TiO_2 nanoparticles(NPs) could adversely impact aquatic ecosystems. However, the aggregation of these NPs could attenuate this effect. In this work, the biological effects of TiO_2 NPs on a marine microalgae Isochrysis galbana were investigated. The aggregation kinetics of TiO_2 NPs under different conditions was also investigated to determine and understand these effects. Results showed that, though TiO_2 NPs had no obvious impact on the size and reproducibility of algal cells under testing conditions, they caused a negative effect on algal chlorophyll, which led to a reduction in photosynthesis. Furthermore, fast aggregation of TiO_2 NPs occurred under all conditions, especially at the pH close to the p Hzpc. Increasing ionic strength and NP concentration also enhanced the aggregation rate.The aggregation and the following sedimentation of TiO_2 NPs reduced their adverse effects on I. galbana. 相似文献
984.
Rongshan Wu Xiaoming Song Yingchen Bai Jie Chen Qian Zhao Shuo Liu Hongbing Xu Tong Wang Baihuan Feng Yi Zhang Liuju Zhong Xuemei Wang Fengchang Wu Wei Huang 《环境科学学报(英文版)》2018,30(9):67-75
With rapid economic development and urbanization in recent decades, China has experienced the worsening of ambient air quality. For better air quality management to protect human health, Chinese government revised national ambient air quality standards(NAAQS) for particulate matter(PM) in 2012(GB3095-2012). To assess the effectiveness of current NAAQS for PM on public health in Chinese population, we conducted a metaanalysis on published studies examining the mortality risk of short-term exposure to PM with aerodynamic diameters less than 10 and 2.5 μm(PM_(10) and PM_(2.5)) in China. The reported24-hour concentrations of PM_(10) and PM_(2.5) in studies ranged from 43.5 to 150.1 μg/m~3 and 37.5 to 176.7 μg/m~3. In the pooled excess, mortality risk estimates of short-term exposure to PM.In specific, per 10 μg/m~3 increase in PM_(10), we observed increases of 0.40%(95%CI: 0.33%,0.47%), 0.57%(95%CI: 0.44%, 0.70%) and 0.49%(95%CI: 0.40%, 0.58%) in total, respiratory and cardiovascular mortality, per 10 μg/m~3 increase in PM_(2.5), we observed increases of 0.51%(95%CI: 0.38%, 0.63%), 0.62%(95%CI: 0.52%, 0.73%) and 0.75%(95%CI: 0.54%, 0.95%) in total,respiratory and cardiovascular mortality. Finally, we derived 125 μg/m~3 for PM_(10) and 62.5 μg/m~3 for PM_(2.5) as 24-hour recommendation values based on the pooled estimates. Our results indicated that current Chinese NAAQS for PM could be sufficient in mitigating the excess mortality risk from short-term exposure to ambient PM. However, future research on longterm exposure cohort studies in Chinese population is also essential in revising annual averages for PM in Chinese NAAQS. 相似文献
985.
Lina Wang Xinran Zheng Svetlana Stevanovi Xin Wu Zhiyuan Xiang Mingzhou Yu Jing Liu 《环境科学学报(英文版)》2018,30(10):98-106
Cooking fume produced by oil and food at a high temperature releases large amount of fine particulate matter(PM) which have a potential hazard to human health. This chamber study investigated particle emission characteristics originated from using four types of oil(soybean oil, olive oil, peanut oil and lard) and different kinds of food materials(meat and vegetable). The corresponding emission factors(EFs) of number, mass, surface area and volume for particles were discussed. Temporal variation of size-fractionated particle concentration showed that olive oil produced the highest number PM concentration for the entire cooking process. Multiple path particle dosimetry(MPPD) model was performed to predict deposition in the human respiratory tract. Results showed that the pulmonary airway deposition fraction was the largest. It was also found that particles produced from olive oil led to the highest deposition. We strongly recommend minimizing the moisture content of ingredients before cooking and giving priority to the use of peanut oil instead of olive oil to reduce human exposure to PM. 相似文献
986.
Oxygenated fuel represents an attractive alternative as an additive for reducing soot emissions.Dimethyl carbonate(DMC) is an oxygenated compound which is a good option to reduce soot,but the detailed characteristics of soot produced from combustion of hydrocarbon fuels blended with DMC are still lacking. The present research studied the nanostructure and reactivity of soot particles in ethylene/DMC normal and inverse diffusion flames. High resolution transmission electron microscopy(HRTEM), X-ray diffraction(XRD), and thermogravimetric analysis(TGA)were used to analyze the nanostructure and reactivity of soot. It was found that DMC addition was effective in decreasing the average weights of soot formed in flames. The results of HRTEM images showed that soot particles obtained with DMC addition showed liquid-like material and tight bonding, and exhibited more highly disorganized layers, which give it higher reactivity than soot obtained without DMC addition. Furthermore, HRTEM was used to analyze soot fringe characteristics consisting of fringe tortuosity, fringe length, and fringe separation. XRD was used to crosscheck the results for fringe separation, and was consistent with HRTEM results. In addition, the mass loss curve of TGA experiments showed that DMC addition could enhance the reactivity of soot particles. 相似文献
987.
基于重金属铜的高度危害性和污泥的高效重复利用的考虑,研究了在污泥吸附剂上去除合成废水中重金属铜的实例。将污泥干燥,研磨并在各种温度下进行热处理,使用SEM和FTIR技术分析了污泥的表面形貌和化学结构。实验所研究的参数是铜离子的初始浓度、反应时间、污泥用量以及污泥的热处理温度。实验数据显示随着污泥用量的增加,Cu+2的去除率增加,并根据使用的浓度范围,研究了Cu+2的初始浓度对重金属铜去除率的影响。对实验数据使用不同等温线进行模拟,获得线性拟合性能较好的等温模型。 相似文献
988.
989.
文中主要对低碳经济发展中物流绿色发展趋势进行了研究,介绍了对低碳经济发展物流绿色发展评价,探讨了低碳经济发展中的不同问卷的调查结果,对物流绿色发展的认知、态度和行动进行了论述,在论述过程中,主要包括对低碳经济发展中的物流认知、对低碳经济发展中的物流态度、对低碳经济发展中的物流行动和对发展低碳经济物流的认知、态度与行动的比较,最后给出了低碳经济发展中物流绿色发展趋势,对低碳经济发展中物流绿色发展给出了研究基础。 相似文献
990.