Study on the Pollution Characteristics and Sources of Ozone in Typical Loess Plateau City
Bin LiZhuangzhi ZhouZhigang XueWei PengYanjun RenLiyuan CaoXinyu FengQingchen YaoJinghua MaPeng XuXuan Chen
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Ground-level ozone is a secondary pollutant produced by photochemical reactions and it adversely affects plant and human health. Taiyuan City, a typical city on the loess plateau, is suffering from severe ozone pollution. We utilized the data from eight national environmental monitoring sites of Taiyuan, including concentrations of O3 and nitric oxide, and meteorological factors, such as air temperature and wind, to study the pollution characteristics and sources of ozone (O3) in Taiyuan in 2018. Results show that during 2018, the maximum value and 90th percentile of the maximum 8-h running average of O3 concentration were 257 μg/m3 and 192 μg/m3, respectively. There were 72 days where the O3 concentration exceeded the standard in 2018, which were mainly during April to August. The O3 concentration increased from March, reached a high level in April through August, and decreased significantly from September. The O3 concentrations displayed a typical “single peak” diurnal variation, which was high during the day with peak at around 13:00–15:00 and low at night. From April to August, the O3 concentrations at Jinyuan was the highest, followed by Xiaodian and Taoyuan, and the O3 concentrations at Shanglan and Nanzhai were the lowest. When the O3 concentration exceeded the standard value, Jinyuan contributed the most to the O3 pollution of Taiyuan, followed by Taoyuan and Xiaodian. High temperature and pressure, south and southwest winds can lead to an increase in O3 concentration. The O3 pollution in the Taiyuan urban area is caused by local generation, and the transportation of polluted air masses containing oxides of nitrogen (NOx) and volatile organic compounds (VOCs) emitted by industries, such as the coking and steel plants in counties of Jinzhong City in southern Taiyuan, and Qingxu County, and some counties in Lyuliang City to the southwest. In addition, the mountain winds and low nitric oxide concentration are the main reasons for the increase of O3 concentration, often observed in Shanglan at night.Keywords:
Ground Level Ozone
Diurnal temperature variation
Loess plateau
Collapsible loess is widely spread in Loess Plateau, northern Shaanxi province. The constructional damage due to side slope and irrigation will be caused if the loess doesn't deal with properly. Based on the analysis features of loess collapsibility and numbers of lab tests, this paper presents the relationship between loess structural parameters and confining pressure, as well water content and porosity ratio. The relevant loess structural parameters were obtained by fitting method. The loess collapsibility characteristics were analyzed with different confining stress, soil water content and porosity ratio. The main triggering factors of loess collapse were also analyzed. The results can further give the scientific evidence when dealing with the collapsible loess.
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Air pollution must take more attention because its effects on human health. One of the most important air pollutants is ground-level ozone O3, which plays an important role in air quality and climate change on the earth. Ozone affected by the other air pollutants, so this paper attempt to study the relationship between hourly, daily and monthly ground-level ozone concentration and hourly, daily and monthly air pollutant concentrations and its effect on ground-level ozone concentration. The other air pollutants are: sulfur dioxide SO2, nitrogen oxides NOx, nitrogen monoxide NO, nitrogen dioxide NO2 and carbon dioxide CO2. The monitoring station is in Babylon University in the south of Al-Hilla city, Iraq for the period 2015-2016. By using statistical analysis, correlation coefficient and some statistics for all air pollutants are computed. Results are: the maximum average ozone concentration is in the summer months June, July and August 39.30 ppb, 45.05 ppb and 36.63 ppb respectively and along the day the peak average ozone concentration is in the afternoon because of high temperature and high solar radiation intensity which is increasing the photochemical activity of ozone. There is no significant correlation between ozone and sulfur dioxide SO2, carbon dioxide CO2 (ρ > 0.05). High significant correlation is appeared between ozone and nitrogen oxides forms (ρ < 0.01). To express the complex relation between ozone and nitrogen oxide forms, proportions such as NO/NO2 and (NOx-NO)/NO is determined which explain the ozone photochemical activity. Ozone concentration decreases with increasing of NO/NO2 and increases with (NOx-NO)/NOx increasing.
Nitrogen dioxide
Ground Level Ozone
Nitrogen oxides
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Nitrogen dioxide
Ground Level Ozone
Seasonality
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By simulating the climate features on loess plateau,the loess ground thermal regime is deriked.By analyzing the calculated data and the tested data for the thermal regime,the changing law of the thermal regime caused by climatic change is explored.The relationship between loess temperature and loess depth in any month is given.It is pointed that the less the loess depth,the more the variation of temperature caused by climate change,and the more is the highest temperature and the less the lowest temperature.Further,this paper indicates that the more the loess depth is,the less is the variation of loess temperature caused by climate change.And the formula,by which the variation of loess temperature in any depth can be calculated,is arrived at.
Loess plateau
Variation (astronomy)
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Abstract In this study, distributing characteristics of five fluorine (F) species in loess in the Shaanxi Loess Plateau (SLP) were determined including unextractable residual F (F re ), extractable water-soluble F (F ws ), exchangeable F (F ex ), F bound to Fe-Mn oxides (F fm ), and F bound to organics (F or ). The results show that unextractable F re represents most percentage of F tf in loess. Of the four extractable F species, the content of F ws is higher than the other three extractable F species in most loess samples. The loess in the southeast SLP has the highest F ws content while the loess in the southwest has the highest F tf content. And the loess in the north SLP contains the lowest overall concentrations of F tf and F ws . Similar to F ws , the respective content of F ex , F fm , and F or in the loess is also very low. However, the total of them and F ws cannot be negligible for F mobility in loess. Overall, the loess in the SLP can be assessed as inferior quality in terms of F as a result of high F ws content in most samples. Based on the F speciation in the loess, F exposure to grazing animals and humans, in fact to children, was assessed, indicating that F in the loess in the southwest SLP might pose a much greater risk to grazing animals than in other part of SLP as the loess contains more F tf . However, there is no concern for the children’s exposure to loess F via ingestion in the study area in the present condition. As for the loess F risk to groundwater, it can be concluded that not only F ws but also the other extractable F including F ex , F fm and F or in loess may be responsible for the F enrichment in local groundwater in the area with the aid of the characteristics of F speciation in loess and distribution of local high-fluoride groundwater.
Loess plateau
Genetic algorithm
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Information on the role of sulfur dioxide in the formation of the concentration of ground-level ozone observed in the cities of Belarus is presented. The problem was solved by constructing a regression equation approximating the dependence of the concentration of ground-level ozone on meteorological conditions and ozone precursors. The presence of sulfur dioxide in urban air leads to a decrease in the concentration of ground-level ozone due to the binding of nitrogen dioxide. It is the photolysis of the latter that is the source of atomic oxygen and the subsequent generation of ozone.
Nitrogen dioxide
Ground Level Ozone
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Ground ozone level was yearly monitored continuously in Shanghai Zhabei ambient air in 2005.Results indicated that 2.88% hourly ozone concentration exceeded 160μg/m~3,class 2 of national standard(GB3095-1996),with the largest non-attainment percentage in June while all data in January,February and December matched standard class 2.Diurnal variation of ozone showed that peak value occurred during 12:00～14:00,with distinct characteristics of photochemical pollutionrelate region.The largest diurnal variation range was found in June and the smallest was found in February.The largest ozone monthly-average concentration was observed in May with the largest hourly concentration 350μg/m~3 in May 19,which demonstrated that ozone formation might be impacted by precursor pollution to large extent.The impact of UV light,atmospheric temperature,wind speed,wind direction,precipitation and relative humidity on ozone variation were also studied.The strong correlation of ozone to NO_2/NO ratio was observed in high temperature and sunny days.
Ground Level Ozone
Diurnal temperature variation
Seasonality
Ground level
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The article is devoted to research of unequal distribution of concentration of ground ozone in airport zone. The purpose of the article is development of method for determination of level of spatial variation of ground ozone between the central zone characterized by high concentration of ozone and the take-off zone characterized by minimum concentration of ozone. The presence of strong negative correlation between the concentration of ground ozone and its major precursor NO is pointed out. The ground ozone is the secondary polluter, photochemical oxidant and the main component of smog. Ozone can damage the respiratory channels of human, lungs. The high concentration of ozone negatively effects vegetation due to its phytotoxicity. Speed of ground ozone generation increases upon low concentrations of NOx up to its maximum value, and then the increase of NOx leads to removal of OH radicals due to reaction with NO2 and promotes the decrease of speed of photochemical formation of ozone. The authors point out the strong negative correlation between the concentration of ground-level ozone and NO. It is shown that these two gas components of atmosphere make it possible to develop the new method for measuring of augmentation of concentration of ground-level ozone in different points of airport in comparison with intensively used take-off and landing zone. It is determined that the averaged amount of such augmentations can be estimated by calculation of total amount of information, produced upon measurements of concentration of NO in compared points of airport territory out of take-off zone.
Ground Level Ozone
Ground level
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The loess tunnel, a kind of subground erosional geomorphy, is common in the loess plateau. Firstly, the classification of loess tunnels in the loess plateau is introduced. Secondly, based on field research, the distribution regularity of loess tunnels is discovered, that is, the density of loess tunnels is becoming lower from the north-west to the south-east. Thirdly, both the loess types and density differ in different depth; finally, the benefits and hazards of loess tunnels are analyzed. Results show that the loess tunnel has double significance: on the one hand, as a kind of geological hazard, it can not only result in serious water and soil loss, but also make damages to various constructions such as highway, railway, oil and gas conveying pipes and folk houses. On the other hand, it is a kind of important way that provides and discharges water for the effluent reservoirs in the loess plateau.
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High concentrations of ground-level ozone have been observed during wintertime in the Uinta Basin of western Utah, USA, beginning in 2010. We analyze existing ozone and ozone precursor concentration data from 38 sites over 11 winter seasons and conclude that there has been a statistically significant (p < 0.02) decline in ozone concentration over the previous decade. Daily exceedances of the National Ambient Air Quality Standard for ozone (70 ppb) have been trending downward at the rate of nearly four per year. Ozone and NOx concentrations have been trending downward at the rates of about 3 and 0.3 ppb per year, respectively. Concentrations of organics in 2018 were at about 30% of their values in 2012 or 2013. Several markers, annual ozone exceedance counts and median ozone and NOx concentrations, were at their largest values in the period 2010 to 2013 and have never recovered since then. We attribute the decline to (1) weakening global demand for oil and natural gas and (2) more stringent pollution regulations and controls, both of which have occurred over the previous decade. We also see evidence of ozone titration when snow cover is absent.
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Ozone Monitoring Instrument
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