نتایج جستجو برای: nitrogen oxides
تعداد نتایج: 136750 فیلتر نتایج به سال:
This article presents design issues of high-sensitive laser absorption spectroscopy systems for nitrogen oxides (NO(x)) detection. Examples of our systems and their investigation results are also described. The constructed systems use one of the most sensitive methods, cavity enhanced absorption spectroscopy (CEAS). They operate at different wavelength ranges using a blue--violet laser diode (4...
VOCs comprise both methane (CH 4) and non-methane volatile organic compounds (NMVOCs). NMVOCs are defined as " all those artificial organic compounds different from methane which can produce photochemical oxidants by reaction with nitrogen oxides in the presence of sunlight " .
During the summer of 2009, concentrations of oxides of nitrogen (NOx), oxides of sulphur (SOx), suspended particulate matter (SPM) and carbon monoxide (CO) were collected over successive periods of about 8 hour at eight sites. High volume air sampler was used to measure the concentration of oxides of nitrogen (NOx), oxides of sulphur (Sox), suspended particulate matter (SPM) and CO monitor was ...
For long, ammonia has been branded as a harmful acid pollutant causing irreversible damage to the environment. Unlike other pollutants like nitrogen oxides (NOx) and sulphur oxides (SOx), ammonia causes acidification to the environment in a more complex and indirect way. The sequence of reactions between ammonia and acidic aerosols followed with microorganisms to form acidic HNO3 has been well ...
BACKGROUND Short-term exposure to air pollution has adverse effects among patients with asthma, but whether long-term exposure to air pollution is a cause of adult-onset asthma is unclear. OBJECTIVE We aimed to investigate the association between air pollution and adult onset asthma. METHODS Asthma incidence was prospectively assessed in six European cohorts. Exposures studied were annual a...
Air quality assessment of the emission from power plant and traffic at Al-Taneem area located at the northern part of the Holy City of Makkah, Saudi Arabia, is investigated. Concentration levels of different pollutants including nitrogen dioxide (NO(2)), sulfur dioxide (SO(2)), carbon monoxide (CO), ozone (O(3)), methane (CH(4)) and total hydrocarbons (THC) as well as some meteorological parame...
From 2012 to 2015, we measured surface ozone, NOx, NO2, and NO levels at three urban sites (Mapipa, Ubungo, and Posta) and two suburban sites (Kunduchi and Vijibweni) in the city of Dar es Salaam and in the village of Mwetemo, a rural area of Bagamoyo, Tanzania. The average hourly O3 concentrations at all sites were between 9 ppb and 30 ppb during our sampling periods. O3 levels at suburban sit...
Oxidized nitrogenous species play a critical role in the formation of ozone in the atmosphere. For both smog chambers and ambient air, a knowledge of the mass balance of such species is useful for the development and validation of methods to model ozone formation. The term NOy has been developed to represent such species although the definition depends on whether it is used by a modeler or an a...
INTRODUCTION Recent laboratory studies and model results indicated a possible effect of soot surface reactions on the nitrogen partitioning in the troposphere [Kalberer et al., 1996; Hauglustaine et al., 1997; Rogaski et al., 1997] and on the stratospheric [Lary et al., 1997] and tropospheric ozone concentrations [Bekki et al., 1997]. However, the model predictions are still speculative because...
The discovery of ammonia-oxidizing archaea (AOA), now generally recognized to exert primary control over ammonia oxidation in terrestrial, marine, and geothermal habitats, necessitates a reassessment of the nitrogen cycle. In particular, the unusually high affinity of marine and terrestrial AOA for ammonia indicates that this group may determine the oxidation state of nitrogen available to asso...
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