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311.
Impact of biogenic terpene emissions from <Emphasis Type="Italic">Brassica napus</Emphasis> on tropospheric ozone over saxony (Germany) 总被引:1,自引:0,他引:1
Renner E Münzenberg A 《Environmental science and pollution research international》2003,10(3):147-153
INTRODUCTION: The role of biogenic emissions in tropospheric ozone production is currently under discussion and major aspects are not well understood yet. This study aims towards the estimation of the influence of biogenic emissions on tropospheric ozone concentrations over Saxony in general and of biogenic emissions from brassica napus in special. MODELLING TOOLS: The studies are performed by utilizing a coupled numerical modelling system consisting of the meteorological model METRAS and the chemistry transport model MUSCAT. For the chemical part, the Euro-RADM algorithm is used. EMISSIONS: Anthropogenic and biogenic emissions are taken into account. The anthropogenic emissions are introduced by an emission inventory. Biogenic emissions, VOC and NO, are calculated within the chemical transport model MUSCAT at each time step and in each grid cell depending on land use type and on the temperature. The emissions of hydrocarbons from forest areas as well as biogenic NO especially from agricultural grounds are considered. Also terpene emissions from brassica napus fields are estimated. SIMULATION SETUP AND METEOROLOGICAL CONDITIONS: The simulations were performed over an area with an extension of 160 x 140 km2 which covers the main parts of Saxony and neighboring areas of Brandenburg, Sachsen-Anhalt and Thuringia. Summer smog with high ozone concentrations can be expected during high pressure conditions on hot summer days. Typical meteorological conditions for such cases were introduced in an conceptual way. RESULTS: It is estimated that biogenic emissions change tropospheric ozone concentrations in a noticeable way (up to 15% to 20%) and, therefore, should not be neglected in studies about tropospheric ozone. Emissions from brassica napus do have a moderate potential to enhance tropospheric ozone concentrations, but emissions are still under consideration and, therefore, results vary to a high degree. CONCLUSIONS: Summing up, the effect of brassica napus terpene emissions on ozone concentrations is noticeable, but not too pronounced. The results give a preliminary estimate on what the effect due to brassica napus emissions could be until better parameterizations can be derived from measurements. 相似文献
312.
Iesce MR Cermola F De Lorenzo F Graziano ML Caliendo B 《Environmental science and pollution research international》2002,9(2):107-109
Irradiation of carboxin (1) with a 500 W UV lamp (filter Pyrex) in CH3CN leads to the products 3, 5-8, 12-14 depending upon the reaction conditions. All photo-products were isolated and characterized. Photooxidation occurred even if unsensitized, while photoalteration was very slow in the absence of oxygen. The main oxygenated-products 3 and 13 were also recovered under biomimetic conditions by exposure of an aqueous solution of 1 to sunlight. 相似文献
313.
Charles J. Weschler Helen C. Shields 《Atmospheric environment (Oxford, England : 1994)》2003,37(39-40):5621
Reactions between ozone and terpenes have been shown to increase the concentrations of submicron particles in indoor settings. The present study was designed to examine the influence of air exchange rates on the concentrations of these secondary organic aerosols as well as on the evolution of their particle size distributions. The experiments were performed in a manipulated office setting containing a constant source of d-limonene and an ozone generator that was remotely turned “on” or “off” at 6 h intervals. The particle number concentrations were monitored using an optical particle counter with eight-channels ranging from 0.1–0.2 to>2.0 μm diameter. The air exchange rates during the experiments were either high (working hours) or low (non-working hours) and ranged from 1.6 to>12 h−1, with intermediate exchange rates. Given the emission rates of ozone and d-limonene used in these studies, at an air exchange rate of 1.6 h−1 particle number concentration in the 0.1–0.2 μm size-range peaked 1.2 h after the ozone generator was switched on. In the ensuing 4.8 h particle counts increased in successive size-ranges up to the 0.5–0.7 μm diameter range. At higher air exchange rates, the resulting concentrations of total particles and particle mass (calculated from particle counts) were smaller, and at exchange rates exceeding 12 h−1, no excess particle formation was detectable with the instrument used in this study. Particle size evolved through accretion and, in some cases, coagulation. There was evidence for coagulation among particles in the smallest size-range at low air exchange rates (high particle concentrations) but no evidence of coagulation was apparent at higher air exchange rates (lower particle concentrations). At higher air exchange rates the particle count or size distributions were shifted towards smaller particle diameters and less time was required to achieve the maximum concentration in each of the size-ranges where discernable particle growth occurred. These results illustrate still another way in which ventilation affects human exposures in indoor settings. However, the ultimate effects of these exposures on health and well being remain to be determined. 相似文献
314.
A field project encompassing wet-only rainwater sampling was initiated as a bilateral Fiji/Australia activity. Normally, biweekly samples were collected, using a wet-only rainwater sampler, and analysed for H+, Na+, K+, Mg2+, NH4
+, Cl–, NO3
–, SO4
2–, PO4
3-, methane sulphonic acid, oxalic acid, formic acid and acetic acid. The pH of the rainwater ranged between 5.730 and 4.480 with an average value of 5.176, slightly lower than the pH of unpolluted rainwater saturated with atmospheric CO2(pH = 5.650). Na+and Cl–were the major ions with average concentrations of 98.15 M and 109.57 M respectively. There is an excellent correlation between the cation sum (average 147.71 eq L-1) and the anion sum (average 142.12 eq L-1) attesting to the quality of the data generated. This paper presents the detailed results of the study for a relatively clean remote island site in Suva, Fiji, latitude 18° 09 S, longitude 178° 27 E, height 6 m, and outlines prospects for further work. 相似文献
315.
Zhiyan Li Pinhua Xie Renzhi Hu Dan Wang Huawei Jin Hao Chen Chuan Lin Wenqing Liu 《环境科学学报(英文版)》2020,32(9):248-255
The nitrate radical (NO3) and dinitrogen pentoxide (N2O5) play an important role in the nocturnal atmosphere chemistry. Observations of NO3 radicals and N2O5 were performed in a semirural ground site at Tai'Zhou in polluted southern China using cavity ring down spectroscopy (CRDS) from 23 May to 15 June 2018. The observed NO3 and N2O5 concentrations were relatively low, with 1 min average value of 4.4 ± 2.2 and 26.0 ± 35.7 pptV, respectively. The N2O5 uptake coefficient was determined to be from 0.027 to 0.107 based on steady state lifetime method. Fast N2O5 hydrolysis was the largest contributor to the loss of NO3 and contributed to substantial nitrate formation, with an average value of 14.83 ± 6.01 µg/m3. Further analysis shows that the N2O5 heterogeneous reactions dominated the nocturnal NOx loss and the nocturnal NOx loss rate is 0.14 ± 0.02 over this region. 相似文献
316.
为探明新集矿区深层地下水离子组成及其演化特征,采集了研究区砂岩水和太灰水等共20个水样,测试分析常规离子和氢氧同位素数据,采用Piper三线图、相关性分析、离子比例系数与饱和指数等方法,探讨了研究区深层地下水水化学特征及其成因。结果表明:(1)研究区砂岩水为高矿化度水,平均矿化度为2 743. 73mg/L,水化学类型主要为Cl-Na型,太灰水多为中矿化度水,平均矿化度为1 468. 33mg/L,水化学类型主要为HCO3·Cl-Na型和Cl-Na型;(2)研究区地下水的补给不仅有大气降水和地表水,还有古气候条件下形成的古溶滤-渗入水,且由于矿物质与深层地下水的水岩作用使得氧同位素发生漂移;(3)含水层中主要发生的水岩相互作用有硅酸盐和蒸发盐岩的溶解及阳离子交替吸附作用,盐岩和石膏在研究区地下水中是反应性矿物,白云石和方解石的溶解在矿区地下水中呈过饱和状态。 相似文献
317.
研究了邻苯二甲酸氢钾、辛基酚、硝基苯等20种有机物在超临界水氧化中的降解效果,探究了温度(325~525℃)和停留时间(30~360s)对超临界水氧化降解有机物的影响,并分析了20种有机物降解速率常数与量子化学参数之间的关系.结果表明,超临界水氧化法能够有效降解有机物,TOC去除率最高可达99%以上.随着反应温度的升高、停留时间的延长,TOC的去除率也随之提高,并且降解规律符合一级动力学.采用密度泛函理论,通过计算得到目标物的量子化学参数,再结合有机物降解的动力学常数进行相关性分析,结果发现,q(H+)、f(-)_(min)和f(0)_(min)与目标物降解率显著相关. 相似文献
318.
Fog composition along the Yangtze River basin: Detecting emission sources of pollutants in fog water
Xianmang Xu Jianmin Chen Chao Zhu Jiarong Li Xiao Sui Lu Liu Jianfeng Sun 《环境科学学报(英文版)》2018,30(9):2-12
To investigate the fog chemistry along the Yangtze River basin, a field observation experiment was performed from Shanghai to Wuhan during November 2015. Fifteen fog water samples were collected by using a three-stage Caltech Active Strand Cloud water Collector(CASCC). The three-stage CASCC was mounted on the board of a ship. PH, electrical conductivity(EC), H_2O_2,HCHO, S(IV), ten inorganic ions, seven organicacids and sixteen trace metal elements were measured in this study. The p H of fog water samples ranged from weakly acidic(pH 4.3) to weakly alkaline(pH 7.05) and the EC ranged from 32.4 to 436.3 μS/cm. The main cations in fog water were NH+4 and Ca~(2+), accounting for 12.35% and 29.07% of those inorganic ions,respectively. In addition, SO_4~(2-) and NO_(-3) contributed to 25.52% and 12.93% to total anion concentrations respectively. Moreover, the dominant kinds of organicacids were formate and oxalate, occupying 45.28% and 28.03% of the total organicacids, respectively. For trace metal elements in fog samples, Al, Fe, Zn, and Ba revealed 34.6%, 16.4%, 19.3%, and 20.9%contributions to these sixteen trace element concentrations, respectively. The results indicated that pollutants were mainly from human activities, including fossil fuel combustion,biomass burning, steel-making, stone quarrying and sand digging. Besides, natural sources including natural background levels and long-range transport of sea salt particles also aggravated the pollution levels in the fog events along the Yangtze River. 相似文献
319.
为了研究我国南方湿润地区河流水化学时空变化特征及控制因素,选择珠江流域第二大水系的北江为研究对象,通过分析2015年6月(汛期)和12月(非汛期)干流和支流河水基本水质参数及主量离子,利用化学计量法及质量守恒法定量评估了自然过程及人类活动共同影响下的流域化学风化特征及其通量.结果表明:①北江河水主量离子浓度非汛期高于汛期.岩石的区域分布和矿山活动构成了河水离子浓度和水化学类型的空间异质性,其中北江干流和支流连江为Ca-HCO3型,而支流滃江则以Ca-SO4型为主.②岩石对北江流域化学风化贡献率依次为碳酸岩(78.44%)>硅酸岩(14.43%)>降水源(5.42%)>蒸发岩(1.71%).基于碳酸岩是北江径流水化学的主要控制因素,滃江流域的矿山开采活动加速了碳酸岩的风化,其对北江流域化学风化的贡献为7%.③汛期与非汛期的碳酸岩风化速率分别为7.49和5.29 t/(km2·月),年化学风化速率为87.63 t/(km2·a).研究显示,由于受水热条件、流域面积以及岩性的影响,北江流域年化学风化速率略大于西江流域,远高于东江以及全球流域化学风化平均值,北江对整个珠江流域的风化贡献较大. 相似文献
320.