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1.
Aeolian (wind) erosion is most common in arid regions. The resulted emission of PM 10 (particulate matter that is smaller than 10 μm in diameter) from the soil has many environmental and socioeconomic consequences such as soil degradation and air pollution. Topsoil resistance to aeolian transport highly depends on the surface composition. The study aim was to examine variations in PM 10 fluxes in a desert-dust source due to surface composition and topsoil disturbance. Aeolian field experiments using a boundary layer wind tunnel alongside soil composition analysis were integrated in this study. The results show variations in PM 10 fluxes (ranging from 9.5 to 524.6 mg m ?2 min ?1) in the studied area. Higher wind velocity increased significantly the PM 10 fluxes in all surface compositions. A short-term natural disturbance caused changes in the aggregate soil distribution (ASD) and increased significantly PM 10 emissions. Considering that PM 10 contains clays, organic matter, and absorbed elements, the recorded PM 10 fluxes are indicative of the potential soil loss and degradation by wind erosion in such resource-limited ecosystems. The findings have implications in modeling dust emission from a source area with complex surfaces. 相似文献
2.
With rapid urbanization and heavy industrialization as well as the rapid increase of cars in China, the effect of energy consumption
on urban air environment is increasingly becoming serious, and has become a hot topic for both scholars and decision-makers.
This paper explores the effect mechanism and regulation of urban energy consumption on the air environment, and summarizes
the framework of the stress effect relationship and the evolutionary process. In accordance with the effect relationship of
the internal factors between the two, analytic approaches studying the stress effect of urban energy consumption on air environment
are proposed, including the analysis of air environment effects caused by urban energy consumption structure change, and the
analysis of air environment effects caused by urban energy economic efficiency change, as well as a decomposition analysis
of air pollutant emission caused by urban energy consumption. Applying the above-mentioned approaches into a case study on
Beijing City, this paper analyzes the effect relationship among urban energy consumption structure improvement, energy economic
efficiency increase and air quality change since the period when Beijing City officially proposed to bid for the 2008 Olympic
Games in 1998. In addition, it further analyzes the effect and contribution of urban industrial activity level, industrial
economic structure, industrial energy intensity, and industrial energy structure as well as emission coefficients on the change
in industrial SO 2 emission, which can provide valuable information to the government for making comprehensive environmental policies, with
the use of the logarithmic mean Divisia index (LMDI) method. It is shown that under the precondition that the industrial economy
maintain a continuous and rapid increase, improvements in energy intensity and a decline in emission coefficients are the
main means for reducing Beijing’s industrial SO 2 emissions. 相似文献
3.
The composite of TiO 2 and zeolite H-ZSM-5 has great photocatalytic ability for organic contaminants over a very large specific surface area and
highlighted adsorption capacity. To describe abiotic degradation of imidacloprid, the photoinduced degradation of the pesticide
imidacloprid in aqueous solutions, in the presence of TiO 2 supported on H-ZSM-5 as photocatalyst, was performed. The study focused on the comparison of the imidacloprid degradation
between photolysis and photocatalysis. The experimental results showed that the degradation of imidacloprid was more rapid
in the condition of photocatalytic than that of photolysis or TiO 2-only. The identification of possible intermediate products during the degradation was investigated by the high-performance
liquid chromatography coupled with electrospray time-of-flight mass spectrometry (HPLC/TOF-MS). The main photocatalytic products
were identified as chloronictinic acid, 1-[(6-chloro-3-pyridinyl) methyl]-2-imidazolidinone and 1-[(6-chloro-3-pyridinyl)
methyl]- N-nitroso-2-imidazolidimine. 相似文献
4.
Not only the nutritional status and biological activity but also the soil ecological functioning or soil health has been impacted profoundly by land degradation in the karst area of southwest China where the karst ecosystems are generally considered as extremely vulnerable to land degradation under intensified land-use changes. The objectives of this study are to elucidate the changes in overall soil quality by a holistic approach of soil nutritional, biological activity, and soil health indicators in the karst area as impacted by intense cultivation and vegetation degradation. Topsoil samples were collected on selected eco-tesserae in a sequence of land degradation in a karst area of southwest Guizhou in 2004. The soil nutrient pools of organic carbon (C org), extractable extracellular carbon (C ext), total soil nitrogen (N t), alkali-hydrolyzable nitrogen (N ah), total phosphorus (P t), available phosphorus (P a) were analyzed by wet soil chemistry. The soil biological properties were studied by means of measurements of microbial biomass carbon (both by fumigation–extraction, FE-C mic, and by calculation from substrate-incubation respiration, SIR-C mic) of respiration [respiration without addition of substrates, basal respiration (BR), and potential respiration (PR) with substrate-incubation] and of soil enzyme activities (invertase, urease, and alkaline phosphatase). Soil health status was assessed by simple indices of C mic/C org and BR/C mic in conjunction with bacterial community structures determined by polymerase chain reaction and denaturing gradient gel electrophoresis. While the nutritional pool parameters, such as C org and C ext, described basically the changes in soil life-supporting capacity with cultivation interference and vegetation declined, those parameters of biological activity such as FE-C mic, SIR, and SIR-C mic as well as bacterial community structures measured by molecular method evidenced well the changes in soil functioning for ecosystem health with the land degradation. 相似文献
5.
填埋是污泥消化处置的方法之一,由于污泥的工程特性较特殊,填埋会引发很多环境岩土工程问题。考虑到填埋工程会进行分层碾压铺填,在标准击实试验的击实功下制备试样,通过污泥与垃圾土混合后的直接剪切试验、渗透特性试验,考虑淋滤液和降解产气压力共同影响,进行边坡稳定分析。结果表明:污泥和垃圾混合后的强度比垃圾土的强度低,比污泥的强度高,改善了污泥的强度特性;污泥掺入垃圾后的渗透系数与垃圾土的渗透系数相当,没有劣化垃圾土的渗透特性,但比污泥的渗透系数有显著提高;随着污泥掺量的增加,边坡安全系数会先提高后降低,因此,应结合试验和稳定计算结果,确定实际工程的污泥掺入比;考虑降解产气对边坡稳定的影响,安全系数会降低约15%~20%。 相似文献
6.
The present research work was intended to find out the useful information on identification, separation and photocatalytic degradation of organic compounds present in leather industry wastewater. The separation of organic compounds present in leather industry wastewater was carried out by solvent extraction. The separated crude extracted products were purified through column chromatography and characterized by UV–vis spectrophotometer, gas chromatography–mass spectrophotometer, liquid chromatography–mass spectrophotometer, 1H and 13C Fourier-transform nuclear magnetic resonance spectroscopy. The elemental analysis of wastewater and solid residue was carried out by inductively coupled plasma-optical emission and X-ray fluorescence spectroscopy. The organic compounds such as nonadec-1-ene, 2-phenylethanol, 2,4-di- tert-butylphenol and other organic compounds in the leather industry wastewater were identified. Out of these organic compounds, 2-phenylethanol was photocatalytically degraded using standard Degussa P-25 TiO 2 (100 mg) photocatalyst under the irradiation of UV light. Result has been shown that 2-phenylethanol was transformed into 2- tert-butyl-4,6-dimethylphenol, 2,6-di- tert-butyl-4-methylphenol then the prolonged time (30 h) irradiation leads to 100 % degradation of 2-phenylethanol. Further possible degradation mechanism of 2-phenylethanol was proposed based on the electrospray ionization mass spectrometry analysis of degraded samples. The degradation of 2-phenylethanol was confirmed by chemical oxygen demand analysis of degraded samples. The physicochemical parameters such as pH, color, chemical oxygen demand, total dissolved solids, electrical conductivity and ionic chromatography analysis of the leather industry wastewater were also measured. 相似文献
7.
The sonochemical degradation of 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) in water and wastewater was investigated at ultrasonic frequency of 850 kHz. The effects of pH, initial concentrations, temperature, power and dissolved organic carbon were examined. The results obtained indicated that the rate of ultrasonic degradation of E2 and EE2 in water and wastewater is influenced by the pH, power, air sparging and the dissolved organic content of the aqueous solutions. Mass degradation rates of E2 and EE2 per kW ranged from 1.7 to 4.0 mg kW ?1 at varying process parameters. The degradation process followed the pseudo-second-order kinetic model with rate constant of 1.71 × 10 ?2 min ?1 at 25 °C. The value for activation energy ( E a = 15.21 kJ mol ?1) obtained from Arrhenius-type plot, indicated that the ultrasonic degradation of steroid hormones is thermodynamically feasible, and does not progress only on radical reactions but other intermediate reaction processes. In wastewater, the higher dissolved organic carbon significantly reduced the effectiveness of degradation of the E2 and EE2 showing that ultrasound treatment will be more effective as a tertiary treatment option in wastewater applications. 相似文献
8.
Chlorophenols are persistent toxins in the natural environment. In this investigation, 2,4-dichlorophenol (2,4-DCP) and pentachlorophenol (PCP) in aqueous media were degraded using an electrokinetic process (EK) and an electro-Fenton process (EF) using stainless steel and graphite as the anode and cathode, respectively. Chlorophenols were degraded via direct electrolysis at the surface of the electrode in the EK process. However, in the EF process, the degradation mechanism includes direct electrolysis and oxidation by hydroxyl radicals. The optimal conditions were a current density of 0.75 mA/cm 2 and an air flow of 0.7 l/min at pH 4. Under the optimal conditions, the 2,4-DCP and PCP removal rates in the EF process were 80.18 and 64.03 %, respectively. The mineralization efficiencies of 2,4-DCP and PCP were 78.23 and 75.77 %, respectively. The results of dechlorination reveal that almost all of the chlorines were released, but some were retained in the intermediates. The dechlorination efficiency revealed that the EF and EK4 processes two chlorines from 2,4-DCP. They released four or five chlorines and four chlorines from PCP, respectively. The kinetic results provide evidence of pseudo-first degradation. The rate constant ( k cp) declined as pH i was increased from 4 to 10. The k cp values reveal that the pH is an important factor that affects the degradation efficiency in the electrochemical process. 相似文献
9.
The rapid urbanization, industrialization, modernization, and the frequent Middle Eastern dust storms have negatively impacted the ambient air quality in Bahrain. The objective of this study is to identify the most critical atmospheric air pollutants with emphasis on their potential risk to health based on calculated AQI (air quality index) values using EPA approach. The air quality datasets of particulate matters (PM 10 and PM 2.5), ozone (O 3), sulfur dioxide (SO 2), nitrogen dioxide (NO 2), and carbon monoxide (CO) were measured in January 2012 and August 2012 using five mobile air quality monitoring stations located at different governorates. The results of this study demonstrated that PM 10 and PM 2.5 are the most critical air pollutants in Bahrain with PM 2.5 prevailing during January 2012 and PM 10 prevailing during August 2012. The corresponding AQI categories were utilized to evaluate spatial variability of particulate matters in five governorates. The impact of meteorological factors such as ambient air temperature, wind speed, relative humidity, and total precipitation on ambient air quality were discussed. The analysis demonstrated that the highest PM 10 concentrations were observed in the Northern Governorate while the highest PM 2.5 concentrations were observed in the Capital, Central, and Northern Governorates during August 2012. It was observed that the levels of PM 2.5 pollution were higher within proximity of the industrial zone. The results suggested that the average PM 2.5/PM 10 ratio in August 2012 was lower than in January 2012 due to the Aeolian processes. This study concludes that higher wind speed, total precipitation, relative humidity rates, and lower ambient air temperature in January 2012 assisted with the dissipation of particulate matter thus lowering the pollution levels of both PM 10 and PM 2.5 in comparison to August 2012. 相似文献
10.
This study represents air quality data of SO 2 and As concentrations around the mining–metallurgical complex Bor (Serbia) from 1994 to 2008. Daily and annual SO 2 concentrations greatly exceed current air quality standards in the studied area. The “hot spot” with the highest SO 2 and As annual concentrations during 15 years was the urban-industrial area (the town core). Daily SO 2 concentrations and meteorological parameters during the period from 2005 to 2008 were statistically analysed to develop suitable prediction equations for daily SO 2 concentrations. Anode copper production is an important but not the only factor that has influence on SO 2 concentrations. By stepwise multiple linear regression analysis, it was determined that daily SO 2 concentrations are most influenced by maximum wind gust, relative humidity and air temperature at all the measuring sites. The prediction equations of daily SO 2 concentrations represent a good model with regression coefficients from 0.854 to 0.926 at all the measuring sites. Correlation analysis showed that eastern and western winds increase SO 2 concentrations, thus increasing the health risk of the inhabitants in the study area. 相似文献
11.
Logistics in China has grown rapidly; in 2015, the freight volume has reached 41 billion ton, increasing by 4.4% year-on-year. At the same time, the pollutant emissions from freight cars account for 70% of total emissions of motor vehicles, which severely affected the air quality. The purpose of this paper is to investigate the effect of logistics on air pollution; we used a new methodology based on vector autoregression of freight turnover, gross domestic product, and urban population. We selected Beijing as our test and created a model using time series data for the period 2000–2014. In this model, permanent residents, freight turnover, and SO 2 emission were used as proxies for population size, logistic services, and degree of air pollution. Our analyses showed that the expansion of logistic services had the biggest effect on air pollution. Moreover, impulse response analysis revealed that logistic growth caused more serious air pollution over a short time, with an ongoing negative effect. GDP growth was only weakly correlated with air pollution, while urban population growth appeared to have little effect. 相似文献
12.
The successful reconstruction of sea surface temperatures using alkenone paleothermometry (U 37k′) has relied on the premise that there is no significant differential degradation of alkenones with different states of unsaturation during diagenetic processes. To test this assumption, we conducted a comparative study of contemporary sediments in oxic and anoxic bottom waters from the Santa Monica Basin, offshore California. Long-chain alkenones were quantified and sea surface temperature were calculated using the calibrated U 37k′–T relationship of Prahl et al. (1988). Our results show that temperature record from the oxic sediments is higher by as much as 4°C compared to those from time-equivalent anoxic sediments as a result of differential degradation of long-chain unsaturated alkenones and bioturbation mixing in the oxic sediments. The differential degradation of C 37:3 vs. C 37:2 alone could account for up to 2.5°C difference between these two records. This finding has significant implication in the interpretation of paleo–sea surface temperature data using alkenone paleothermometry. 相似文献
13.
This paper presents the analysis and interpretation of ambient particulate matter concentrations measured as PM 10 at a network of six air monitoring stations in Kathmandu valley during the years, 2003 through 2005. The purpose was to understand the pollution trends associated with different areas considering levels particulate matter concentrations representing the ambient air quality of Kathmandu valley. The study indicate that particulate concentrations (PM 10) measured are persistently higher at air sampling sites representing roadside areas compared to the background sites. The inter-station network variability with respect the particulate pollution suggests optimizing resources. The comparison of annual average PM 10 concentration observed at six air-monitoring sites in Kathmandu Valley with standard annual average concentration prescribed by World Health Organization as well as Europe Union indicates serious PM 10 pollution in Kathmandu valley. 相似文献
14.
Ambient air pollution, particularly in the urban environment of developing countries, has turned out to be a major health risk factor. We explore the compounded impact of age sensitivity, exposure, poverty, co-morbidity, etc., along with composite air pollution in determining morbidity and health burden of people in Lucknow, India. This cross-sectional study is confined to analyse respiratory health status across different socio-economic and geographic locations using n = 140 in-depth questionnaire method. We used mean daily ambient air pollution data of PM10, PM2.5, SO2, and NO2 for the 2008–2018 period. We used the ecological model framework to assess the risk at different hierarchical levels and compounded severity on a spatial scale. We also used Logistic regression model with log odds and odds ratio to analyze the association of risks outcomes with composite air pollution scores calculated using the principal component analysis method. There is a strong association of location-specific respiratory disease prevalence with an overall 32 percent prevalence. The prevalence of ecological model 1 (individual domain) is 4.3 percent, while ecological model 2 (community domain) has the highest prevalence at 32.4 percent. The logistic regression model shows that respiratory disease load is positively associated with age sensitivity (P < .001) and composite pollution level (P < .001). For another model with suffocation as the outcome variable, composite pollution level (P < .001) and exposure (P < .001) are positively associated. Optimum interventions are required at Ecological models 1, 2, and 3 levels for better respiratory health outcomes. 相似文献
15.
The environment prevalent in ocean necessitates the piles supporting offshore structures to be designed against lateral cyclic loading initiated by wave action, which induces deterioration in the strength and stiffness of the pile-soil system introducing progressive reduction in the bearing capacity associated with increased settlement of the pile foundation. A thorough and detailed review of literature indicates that significant works have already been carried out in the relevant field of investigation. It is a well established phenomenon that the variation of relative pile-soil stiffness ( K rs ) and load eccentricity ( e/D) significantly affect the response of piles subjected to lateral static load. However, the influence of lateral cyclic load on axial response of single pile in sand, more specifically the effect of K rs and e/D on the cyclic behavior, is yet to be investigated. The present work has aimed to bridge up this gap. To carry out numerical analysis (boundary element method), the conventional elastic approach has been used as a guideline with relevant modifications. The model developed has been validated by comparing with available experimental (laboratory model and field tests) results, which indicate the accuracy of the solutions formulated. Thereafter, the methodology is applied successfully to selected parametric studies for understanding the magnitude and pattern of degradation of axial pile capacity induced due to lateral cyclic loading, as well as the influence of K rs and e/D on such degradation. 相似文献
16.
Air quality monitoring was performed at the measuring sites in the urban-industrial and suburban zone during the period 2005–2007 in Bor (Serbia). Arsenic, lead, cadmium, copper and sulphur dioxide are predominantly of industrial origin as a result of copper production in the study area. The smelter, which is a part of the Mining-Metallurgical Complex Bor, is the major pollution source. As and SO 2 are the pollutants which pose the biggest threat for the inhabitants of the Bor area, since the measured concentrations exceed the proposed limit values. The obtained concentrations showed that the endangered areas are in close vicinity of the smelter, as well as in the directions of the prevailing winds. By grouping these pollutants into separate clusters, the results of cluster analysis confirmed high loads of As and SO 2 in the air. The results of principal component analysis showed that copper production has major influence on air pollution. 相似文献
17.
Due to its negative impact on the living environment of human beings, ambient air pollution has become a global challenge to human health. In this study, surface observations of six criteria air pollutants, including PM 2.5, PM 10, SO 2, NO 2, CO and O 3, were collected to investigate the spatial and temporal variation in the Beijing–Tianjin–Hebei (BTH) region during 2013–2016 and to explore the relationships between atmospheric pollutants and meteorological variables using quantile regression model (QRM) and multiple linear regression model (MLRM). The results show that BTH region has experienced significant air pollution, and the southern part generally has more severe conditions. The annual average indicates clear decreasing trends of the particulate matters, SO 2 and CO concentrations over the last 4 years and slight increasing trends of NO 2 and O 3 in several cities. The seasonal and monthly characteristics indicate that the concentrations of five species reach their maxima in the winter and their minima in the summer, whereas O 3 has the opposite behaviour. Finally, the pseudo R2 values show that the QRMs have the best performance in the winter, followed by spring, fall, and summer. Specifically, all the meteorological factors have significant impacts on air pollution but change with pollutants and seasons. The MLRM results are generally consistent with the QRM results in all seasons, and the inconsistencies are more common in the fall and winter. The results of this research provide foundational knowledge for predicting the response of air quality to climate change in the BTH region. 相似文献
18.
This work aims to estimate the levels of lead (Pb), nickel (Ni), manganese (Mn), vanadium (V) and chromium (Cr) corresponding to a 3-month PM 10 sampling campaign conducted in 2008 in the city of Dunkerque (northern France) by means of statistical models based on partial least squares regression (PLSR), artificial neural networks (ANNs) and principal component analysis (PCA) coupled with ANN. According to the European Air Quality Directives, because the levels of these pollutants are sufficiently below the European Union (EU) limit/target values and other air quality guidelines, they may be used for air quality assessment purposes as an alternative to experimental measurements. An external validation of the models has been conducted, and the results indicate that PLSR and ANNs, with comparable performance, provide adequate mean concentration estimations for Pb, Ni, Mn and V, fulfilling the EU uncertainty requirements for objective estimation techniques, although ANNs seem to present better generalization ability. However, in accordance with the European regulation, both techniques can be considered acceptable air quality assessment tools for heavy metals in the studied area. Furthermore, the application of factor analysis prior to ANNs did not yield any improvements in the performance of the ANNs. 相似文献
19.
Tropospheric ozone (O 3) acts as greenhouse gas and air pollutant. Over the last 100 years, tropospheric O 3 levels increased above background by factor 2.5 in the northern hemisphere and by factor 3–4 across Europe. The gas poses a potential risk to forest ecosystems in many mountain areas. There, O 3 concentrations result from long-range transport and are influenced by removal processes (dry deposition, gas phase and cloud removal, reduction on wet aerosols). Most trend studies analyzed annual-mean concentrations. We focus on winter O 3 trends at high altitudes in the German/Czech Erzgebirge (period 1981–2020) to avoid major noise from photochemical reactions and to better explain recent O 3 behavior in Central Europe. Hourly air quality and meteorological data from four stations (Carlsfeld, CAR; Fichtelberg, FIB; Schwartenberg, SWB; Zinnwald, ZIW) were used to analyze O 3 trends. The data can explain the complex O 3 formation and removal behavior.Three distinct periods of O 3-concentration trends can be discerned: i) Until the late 1980s, characterized by relatively low O 3 concentrations. ii) Dramatic transformation in the 1990s with changing air pollution in Central Europe. Strong O 3-concentration increase at FIB is corroborated by data from CAR and ZIW. iii) Stabilization as of 1997/98, when O 3 concentrations remained at the same level for all four stations, despite general regional air pollution decrease. Key results are:a) Winter O 3 trends mainly depend on O 3 concentration of air masses transported to the stations and on the O 3-removal potential (ORP) of clouds, not on local formation processes.b) ORP differs between clouds and fog, depending on droplet chemical composition. Fog from the North Bohemian Basin showed the highest ORP due to reaction with liquid phase S(IV). However, O 3 reactions with O 2− in fog droplets showed high ORP, too, depending on cloud-water pH values and NO x concentrations.c) So-called “Bohemian fog” decreased, and with it related ORP, while that of clouds from westerly and northwesterly air masses remained nearly unchanged since 1997/98.d) Decreasing ORP in clouds and fog (= higher O 3 concentration) oppose decreasing O 3 concentrations in westerly air masses. Both effects lead to unchanged O 3 levels in the Erzgebirge since 1997/98. 相似文献
20.
The impact of the air pollution generated by any industrial activities may be further aggravated if the location of the industrial area is exposed to certain atmospheric characteristics. Under such conditions, the likelihood of accumulation of local air pollution is high. This paper uses two approaches (statistical and numerical simulation) to investigate the contribution of atmospheric processes towards degradation of air quality. A case study of the two approaches was conducted over Sohar Industrial Area in the Sultanate of Oman. Measured wind data were used to account for specific atmospheric characteristics such as stagnation, ventilation, and recirculation using the statistical approach. In the second approach, numerical weather prediction model was used to simulate mesoscale circulation phenomena such as sea breeze and its contribution to the processes affecting the air quality. The study demonstrates that the atmospheric processes appear to contribute substantially to the degradation of air quality in the Sohar Industrial Area. The statistical analysis shows that the atmospheric dilution potential of Sohar Industrial Area is prone to stagnation and recirculation, rather than ventilation. Moreover, model simulation shows that there is a seasonal variation in the contribution of atmospheric processes to the degradation of the air quality at Sohar Industrial Area. 相似文献
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