首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 296 毫秒
1.
In this study, we used satellite data (GOME and MOPITT) together with a global chemical-transport-model of atmosphere (MOZART-2) to characterize the chemical/aerosol composition over eastern China. We then estimated the effects of local emissions in China on the chemical budgets in other regions of the world. Likewise, we also investigated the effects of air pollution from other regions on the chemical budget over eastern China. The study shows that the column CO and NO x concentrations are also high in eastern China. The high CO and NO x concentrations produce modest levels of O3 concentrations during summer (about 40 to 50 ppbv) and very low O3 during winter (about 10 to 20 ppbv) in eastern China. The calculated NO2 column is fairly consistent from the GOME measurement. The calculated CO column is underestimated from the MOPITT measurement. One of the reasons of the underestimation of the predicted CO is due to a fact that the CO emissions were taken without considering the rapid increase of emissions from 1990 to 2000. The calculated surface O3 is consistent with the measured values, with strong seasonal variations. However, the measurement is very limited, and more measurements in eastern China will be needed. The column NO2 has a very strong seasonal variation in eastern China, with the highest concentrations during winter and the lowest concentrations during summer. The cause of this seasonal variability is mainly due to the seasonal changes in the chemical loss of NO x , which is very high in summer and very low during winter. The effects of the local emissions in China and long-range transport from other regions on the chemical distributions in eastern China are studied. The results show that NO x concentrations in eastern China are mostly caused by the local emissions in China, especially during the winter. The CO concentration over eastern China is from both the local emissions (30% to 40%) and the transport from other regions. Likewise, the CO emissions in China have an important effect on the other regions of the world, but the effect is limited in the northern hemisphere. The local emissions in China also have an important effect on surface O3 concentrations. During winter, the local emissions reduce the surface O3 concentrations by 30 to 50%. During summer, the local emissions produce about 50 to 70% of the O3 concentration in eastern China.  相似文献   

2.
Automobile exhaust emissions are becoming increasingly serious with the drastic increase of the number of vehicles in Beijing. In order to investigate the air pollution level and characteristics in the areas near the main traffic lines in Beijing and to identify the contributions from traffic and other sources, gaseous pollutants including NOx, CO, O3, SO2, and meteorological parameters have been monitored at a monitoring site and a contrasting site in winter and summer in 2006. The volumes of vehicles on Beiyuan Road were recorded. The average concentrations of NO, NO2, NOx, CO, O3, and SO2 at the monitoring site were 0.148 mg/m3, 0.107 mg/m3, 0.333 mg/m3, 5.110 mg/m3, 0.006 mg/m3, and 0.157 mg/m3, respectively during the sampling period in winter and 0.021 mg/m3, 0.068 mg/m3, 0.101 mg/m3, 4.170 mg/m3, 0.083 mg/m3, and 0.056 mg/m3, respectively in summer. The high concentrations of CO and O3 reflect the influence of vehicles emission near the traffic lines evidently. The higher concentrations of CO, NO and O3 in summer may indicate that the characteristics of traffic pollution were more pronounced in summer. Results of regression analysis showed that in winter the concentrations of SO2 and CO were significantly positively correlated with the emission of heating boilers at night and negatively correlated with wind speed in daytime. The concentrations of NO and NOx were negatively correlated with wind speed, positively correlated with emission of heating boilers in daytime and positively correlated with traffic density at nighttime. The concentrations of NO2 were positively correlated with the emission of heating boilers in daytime and traffic density at nighttime. In summer, the air quality at the monitoring site and the contrasting site was mainly influenced by the traffic emissions.  相似文献   

3.
In this study, the chemical and physical losses of nitrogen oxides (NOx) over the Korean peninsula were discussed in order to better understand the effects of the NOx losses on the tropospheric NO2 columns. Initially, it was found that the physical loss processes due to dry and wet depositions had almost negligible impacts on the NOx loss processes over the Korean peninsula. In contrast, the hourly NOx chemical column losses were large at ??1014 molecules cm?2 h?1. The amounts of NOx removed for 1 hour account for approximately 33?C35% of the episode-averaged tropospheric NO2 columns during summer over the Korean peninsula. The NOx chemical column loss rates were 24.1?C70.9 times larger than the NOx physical column loss rates. In a budget analysis of the NOx chemical column losses, HNO3 formation via the reaction of OH + NO2 had the largest contribution toward the NOx chemical losses (42?C55% during fall and winter seasons; 76?C77% during spring; 92?C93% during summer). Large amounts of NOx were also removed by heterogeneous nitrate formation via N2O5 condensation during the cold seasons (42?C56%) over the Korean peninsula. The columnar NOx chemical losses took place mainly due to the two chemico-physical reaction processes, and also showed seasonal variations. PAN (Peroxyacetyl Nitrate) is another NO2 reservoir of potential importance. If the influence of the PAN-related chemistry on the NOx budget is considered, it can result in an approximate 69% increase in the NOx chemical column loss during summer. Such increases in the amounts of NOx removed for 1 hour due to the formation of PAN were equivalent to 56?C58% of the episode-averaged tropospheric NO2 columns during summer over the Korean peninsula. Such active NOx chemical losses during summer are another main factor for the tropospheric NO2 columns exhibiting their smallest values during summer.  相似文献   

4.
利用2010—2012年对流层臭氧（O3）及其多种前体物的卫星遥感资料和全球水汽再分析资料,研究东亚区域O3及其前体物的时空分布,以及在中国东部（分为南、北两部分）相关性的季节变化。结果表明:东亚区域NO2与CO的对流层柱含量均表现为冬季高、夏季低的时空变化形式。O3对流层柱含量夏季达到峰值,冬季为谷值。中国东部的北部与南部地区O3与NO2均在夏秋季呈正相关,冬春季呈负相关。夏季大部分地区NOx的光化学循环反应对O3生成有积极的促进作用,冬季大部分地区O3的光化学循环生成受到抑制。O3与CO在北部地区夏秋季和南部地区夏季正相关性最大,无论是在北部还是南部地区,O3与CO的相关性在轻污染情况下最大,而在重污染和背景情况下较小,表明重污染气团向下风方的输送更有利于O3的光化学生成。O3与水汽在北部和南部地区的多数时间均呈较显著的正相关性,而在南部地区夏季和北部地区冬季具有较大的负相关性,反映出不同的环流形式、气团来源及伴随的天气条件变化对O3分布的影响。  相似文献   

5.
A photochemical box model is used to simulate seasonal variations in concentrations of sulfur compounds at latitude 40° S. It is assumed that the hydroxyl radical (OH) addition reaction to sulfur in the dimethyl sulfide (DMS) molecule is the predominant pathway for methanesulfonic acid (MSA) production, and that the rate constant increases as the air temperature decreases. Concentration of the nitrate radical (NO3) is a function of the DMS flux, because the reaction of DMS with NO3 is the most important loss mechanism of NO3. While the diurnally averaged concentration of OH in winter is a factor of about 8 smaller than in summer, due to the weak photolysis process, the diurnally averaged concentration of NO3 in winter is a factor of about 4–5 larger than in summer, due to the decrease of DMS flux. Therefore, at middle and high latitudes in winter, atmospheric DMS is mainly oxidized by the reaction with NO3. The calculated ratio of the MSA to SO2 production rates is smaller in winter than in summer, and the MSA to non-sea-salt sulfate (nssSO4 2-) molar ratio varies seasonally. This result agrees with data on the seasonal variation of the MSA/nssSO4 2- molar ratio obtained at middle and high latitudes. The calculations indicate that during winter the reaction of DMS with NO3 is likely to be a more important sink of NOx (NO+NO2) than the reaction of NO2 with OH, and to serve as a significant pathway of the HNO3 production. If dimethyl sulfoxide (DMSO) is produced through the OH addition reaction and is heterogeneously oxidized in aqueous solutions, half of the nssSO4 2- produced in summer may be through the oxidation process of DMSO. It is necessary to further investigate the oxidation products by the reaction of DMS with OH, and the possibility of the reaction of DMS with NO3 during winter.  相似文献   

6.
Continuous measurements of ozone and its precursors including NO, NO2, and CO at an urban site (32°03′N, 118°44′E) in Nanjing, China during the period from January 2000 to February 2003 are presented. The effects of local meteorological conditions and distant transports associated with seasonal changed Asian monsoons on the temporal variations of O3 and its precursors are studied by statistical, backward trajectory, and episode analyses. The diurnal variation in O3 shows high concentrations during daytime and low concentrations during late night and early morning, while the precursors show high concentrations during night and early morning and low concentrations during daytime. The diurnal variations in air pollutants are closely related to those in local meteorological conditions. Both temperature and wind speed have significant positive correlations with O3 and significant negative correlations with the precursors. Relative humidity has a significant negative correlation with O3 and significant positive correlations with the precursors. The seasonal variation in O3 shows low concentrations in late autumn and winter and high concentrations in late spring and early summer, while the precursors show high concentrations in late autumn and winter and low concentrations in summer. Local mobile and stationary sources make a great contribution to the precursors, but distant transports also play a very important role in the seasonal variations of the air pollutants. The distant transport associated with the southeastern maritime monsoon contributes substantially to the O3 because the originally clean maritime air mass is polluted when passing over the highly industrialized and urbanized areas in the Yangtze River Delta. The high frequency of this type of air mass in summer causes the fact that a common seasonal characteristic of surface O3 in East Asia, summer minimum, is not observed at this site. The distant transports associated with the northern continental monsoons that dominate in autumn and winter are related to the high concentrations of the precursors in these two seasons. This study can contribute to a better understanding of the O3 pollution in vast inland of China affected by meteorological conditions and the rapid urbanization and industrialization.  相似文献   

7.
The chemical composition of regional background aerosols, and the time variability and sources in the Western Mediterranean are interpreted in this study. To this end 2002–2007 PM speciation data from an European Supersite for Atmospheric Aerosol Research (Montseny, MSY, located 40 km NNE of Barcelona in NE Spain) were evaluated, with these data being considered representative of regional background aerosols in the Western Mediterranean Basin. The mean PM10, PM2.5 and PM1 levels at MSY during 2002–2007 were 16, 14 and 11 µg/m3, respectively. After compiling data on regional background PM speciation from Europe to compare our data, it is evidenced that the Western Mediterranean aerosol is characterised by higher concentrations of crustal material but lower levels of OM + EC and ammonium nitrate than at central European sites. Relatively high PM2.5 concentrations due to the transport of anthropogenic aerosols (mostly carbonaceous and sulphate) from populated coastal areas were recorded, especially during winter anticyclonic episodes and summer midday PM highs (the latter associated with the transport of the breeze and the expansion of the mixing layer). Source apportionment analyses indicated that the major contributors to PM2.5 and PM10 were secondary sulphate, secondary nitrate and crustal material, whereas the higher load of the anthropogenic component in PM2.5 reflects the influence of regional (traffic and industrial) emissions. Levels of mineral, sulphate, sea spray and carbonaceous aerosols were higher in summer, whereas nitrate levels and Cl/Na were higher in winter. A considerably high OC/EC ratio (14 in summer, 10 in winter) was detected, which could be due to a combination of high biogenic emissions of secondary organic aerosol, SOA precursors, ozone levels and insolation, and intensive recirculation of aged air masses. Compared with more locally derived crustal geological dusts, African dust intrusions introduce relatively quartz-poor but clay mineral-rich silicate PM, with more kaolinitic clays from central North Africa in summer, and more smectitic clays from NW Africa in spring.  相似文献   

8.
Synoptic Climatology of Air Pollution in Moscow   总被引：8，自引：0，他引：8  
Summary Seasonal synoptic indices are developed employing principal components analysis and cluster analysis for Moscow and using surface and upper air meteorological data. Synoptic types are analysed in terms of circulation patterns and air mass characteristics. The indices are used to examine weather-induced variability in CO and NO2 concentrations for different land use types and in the context of multiple pollution sources. Anticyclonic conditions in spring, summer and autumn are identified as producing high pollution concentrations. Local depressions developing in the low pressure gradient fields in summer are another synoptic type resulting in high levels of air pollution. Extremely cold anticyclonic conditions in winter result in high CO but low NO2 levels. Weather patterns characterised by strong winds associated either with an established zonal flow or the passage of a cold front caused high NO2 concentrations in the areas affected by elevated sources. Received October 28, 1997 Revised January 26, 1998  相似文献   

9.
Air pollutant emission rates and concentrations in medieval churches   总被引：1，自引：0，他引：1  
A series of indoor air quality parameters were determined in two medieval churches, in Cyprus (temperature, relative humidity, total and UV solar radiation, CO2 indoors and O3, NO, NO2 *, HNO3 *, HCl, HCOOH, CH3COOH indoors and outdoors). These data were used as input in a validated indoor air quality model to predict indoor air pollutant source strengths and species concentrations that resulted from dark or photochemical reactions. The NO and NO2 emission rates due to the burning of incense or candles were estimated. Model results revealed that heterogeneous NO formation takes place simultaneously with the heterogeneous HONO formation. Also, model application has shown that indoor NOx emissions resulted in decreased free radical concentrations, in contrast to the organic compound emissions, which increased free radical concentrations. This effect of indoor emissions on indoor radicals can partly explain the indoor enhancement/depression of indoor gaseous acid formation.  相似文献   

10.
Formic and acetic acid measured as daily averages in 1993–1994show equal and highly correlated concentrations up to 3 ppb in the summer(May–August). In the winter (October–March) the formicacid/acetic acid ratio was 0.6 and the formic acid concentrations wereusually below 1 ppb. In winter the carboxylic acids correlate withOx, NOy, SO2 and particulatesulphur. The main sources are suggested to be ozonolysis of anthropogenicalkenes and reactions between peroxyacetyl radicals and RO2radicals. In spring–summer the carboxylic acids correlate withO3, Ox, HNO3, PAN,NOy, SO2, particulate sulphur and temperature.In addition to the sources of the winter a contribution from ozonolysis ofbiogenic alkenes is likely. Quite similar formic acid/acetic acid ratios forall wind directions suggest that the source(s) are atmospheric oxidationprocesses distributed over large areas. The highest concentrations occurringfor winds from east to south and the correlation with e.g., particulatesulphur indicate chemical production in polluted air masses during longrange transport.  相似文献   

11.
Several years of continuous measurements of surfaceozone at Norwegian monitoring sites are studied in aclimatological way. The monitoring sites are at rurallocations extending from 58°N, a few hundredkilometers from the European continent and into theArctic at 79°N. The ozone observations are sorted intoclasses of integrated NOx emissions along 96 h backtrajectories. The average seasonal cycles of ozone areestimated for each class separately. The differencesindicate the change from the background air due toanthropogenic emissions. The average seasonal cycle ofozone in the cleanest air masses showed a maximum inspring and a minimum during summer and autumn at allsites, but the spring maximum was more pronounced atthe southernmost locations. Polluted air masses showedan ozone deficit during winter and a surplus duringsummer. The deviation from the background was clearlylinked to the integrated NOx emission along thetrajectories. In summer the calculations indicate thatthe number of ozone molecules formed per NOx moleculedrops with increasing emissions. The average seasonalcycle of ozone at Birkenes for different transportsectors indicate that the most pronounced ozoneformation takes place in air masses from E-Europe/Russia.  相似文献   

12.
The spatial distribution of trace gases exhibit large spatial heterogeneity over the Indian region with an elevated pollution loading over densely populated Gangetic Plains (IGP). The contending role and importance of anthropogenic emissions and meteorology in deciding the trace gases level and distribution over Indian region, however, is poorly investigated. In this paper, we use an online regional chemistry transport model (WRF/Chem) to simulate the spatial distribution of trace gases over Indian region during one representative month of only three meteorological seasons namely winter, spring/summer and monsoon. The base simulation, using anthropogenic emissions from SEAC4RS inventory, is used to simulate the general meteorological conditions and the realistic spatial distribution of trace gases. A sensitivity simulation is conducted after removing the spatial heterogeneity in the anthropogenic emissions, i.e., with spatially uniform emissions to decouple the role of anthropogenic emissions and meteorology and their role in controlling the distribution of trace gases over India. The concentration levels of Ozone, CO, SO2 and NO2 were found to be lower over IGP when the emissions are uniform over India. A comparison of the base run with the sensitivity run highlights that meteorology plays a dominant role in controlling the spatial distribution of relatively longer-lived species like CO and secondary species like Ozone while short-lived species like NOX and SO2 are predominantly controlled by the spatial variability in anthropogenic emissions over the Indian region.  相似文献   

13.
The source strength of volatile organic compounds (VOCs) emitted by vegetation is of great interest for the understanding of processes in atmospheric chemistry and climate change. In this study terpene emissions from branches of European beech (Fagus sylvatica L.) were studied in a deciduous forest. Using the branch enclosure technique changes in the emission pattern and the variation of emission rates over the year were investigated over two consecutive vegetation periods. More than 10 monoterpene compounds were found in the emissions, among which sabinene dominates. For most compounds the emission pattern changed only slightly over the year. Interestingly, two compounds tentatively identified as para-cymene and cis-ocimene showed differences in the emission behaviour in late summer compared to the other terpenes. In contrast to previous studies our investigation characterise European beech as a strong emitter. For the main compounds the emission rates changed up to two orders of magnitude as a function of temperature and light over the day. In general, highest emission rates were observed in summer and lowest in fall. A seasonality was characterized by a temperature independent decline of emissions in late summer, resulting in changes of the standard emission rate on the order of one magnitude. A standard emission factor of up to 3.5 nmol m−2s−1 for the sum of measured terpenes was calculated. No emissions were found in early spring even though leaves were fully developed and temperature and light conditions were moderate. The results underline the importance of characterising the annual variation of the emission behaviour. Especially for the up-scaling to global VOC emissions, seasonal influences have to be considered to achieve realistic emission inventories.  相似文献   

14.

This study presents the chemical composition (carbonaceous and nitrogenous components) of aerosols (PM2.5 and PM10) along with stable isotopic composition (δ13C and δ15N) collected during winter and the summer months of 2015–16 to explore the possible sources of aerosols in megacity Delhi, India. The mean concentrations (mean?±?standard deviation at 1σ) of PM2.5 and PM10 were 223?±?69 µg m?3 and 328?±?65 µg m?3, respectively during winter season whereas the mean concentrations of PM2.5 and PM10 were 147?±?22 µg m?3 and 236?±?61 µg m?3, respectively during summer season. The mean value of δ13C (range: ??26.4 to ??23.4‰) and δ15N (range: 3.3 to 14.4‰) of PM2.5 were ??25.3?±?0.5‰ and 8.9?±?2.1‰, respectively during winter season whereas the mean value of δ13C (range: ??26.7 to ??25.3‰) and δ15N (range: 2.8 to 11.5‰) of PM2.5 were ??26.1?±?0.4‰ and 6.4?±?2.5‰, respectively during the summer season. Comparison of stable C and N isotopic fingerprints of major identical sources suggested that major portion of PM2.5 and PM10 at Delhi were mainly from fossil fuel combustion (FFC), biomass burning (BB) (C-3 and C-4 type vegitation), secondary aerosols (SAs) and road dust (SD). The correlation analysis of δ13C with other C (OC, TC, OC/EC and OC/WSOC) components and δ15N with other N components (TN, NH4+ and NO3?) are also support the source identification of isotopic signatures.

  相似文献   

15.
A coupled chemical/dynamical model (SOCOL-SOlar Climate Ozone Links) is applied to study the impacts of future enhanced CO and NOx emissions over eastern China on regional chemistry and climate. The result shows that the increase of CO and NOx emissions has significant effects on regional chemistry, including NOx, CO, O3, and OH concentrations. During winter, the CO concentration is uniformly increased in the northern hemisphere by about 10 ppbv. During summer, the increase of CO has a regional distribution. The change in O3, concentrations near eastern China has both strong seasonal and spatial variations. During winter, the surface O3, concentrations decrease by about 2 ppbv, while during summer they increase by about 2 ppbv in eastern China. The changes of CO, NOx, and O3, induce important impacts on OH concentrations. The changes in chemistry, especially O3, induce important effects on regional climate. The analysis suggests that during winter, the surface temperature decreases and air pressure increases in central-eastern China. The changes of temperature and pressure produce decreases in vertical velocity. We should mention that the model resolution is coarse, and the calculated concentrations are generally underestimated when they are compared to measured results. However, because this model is a coupled dynamical/chemical model, it can provide some useful insights regarding the climate impacts due to changes in air pollutant emissions.  相似文献   

16.
By means of a three-dimensional meteorological model (MM5) and a chemical model,the distributions of tropospheric ozone and its precursors over China have been simulated in summer and winter time,16-18 August 1994 and 7-9 January 1995.The distribution of ozone over the Tibetan Plateau in summer time is deeply discussed.The simulated results indicate that thedistributions of surface ozone and NOx are in good agreement with observed results,and human activities and photochemical reactions are the main factors controlling the surface ozone and NOx concentrations.In addition,higher ozone concentrations are coincided with the air convergence,and the lower concentrations are related to the air divergence.In summer,over the Tibetan Plateau the strong flow convergence results in higher ozone concentrations in the lower troposphere:and the strong flow divergence results in lower ozone concentrations in the upper troposphere.In winter time ozone concentrations show large-scale characteristics controlled by westerly flow,and in the jet area they are lower than those outside the jet.  相似文献   

17.
Campaigns were conducted to measure Organic Carbon (OC) and Elemental Carbon (EC) in PM2.5 during winter and summer 2003 in Beijing. Modest differences of PM2.5 and PM10 mean concentrations were observed between the winter and summer campaigns. The mean PM2.5/PM10 ratio in both seasons was around 60%, indicating PM2.5 contributed significantly to PM10. The mean concentrations of OC and EC in PM2.5 were 11.2±7.5 and 6.0±5.0μg m-3 for the winter campaign, and 9.4±2.1 and 4.3±3.0 μg m-3 for the summer campaign, respectively. Diurnal concentrations of OC and EC in PM2.5 were found high at night and low during the daytime in winter, and characterized by an obvious minimum in the summer afternoon. The mean OC/EC ratio was 1.87±0.09 for winter and Z39±0.49 for summer. The higher OC/EC ratio in summer indicates some formation of Secondary Organic Carbon (SOC). The estimated SOC was 2.8 μg m-3 for winter and 4.2μg m-3 for summer.  相似文献   

18.
Field measurement programs in Brazil during the dry seasons in August and September 1979 and 1980 have demonstrated the large importance of the continental tropics in global air chemistry. Many important trace gases are produced in large amounts over the continents. During the dry season, much biomass burning takes place, especially in the cerrado regions, leading to a substantial emission of air pollutants, such as CO, NO x , N2O, CH4 and other hydrocarbons. Ozone concentrations are enhanced due to photochemical reactions. The large biogenic organic emissions from tropical forests play an important role in the photochemistry of the atmosphere and explain why CO is present in such high concentrations in the boundary layer of the tropical forest. Carbon monoxide production may represent more than 3% of the net primary productivity of the tropical forests. Ozone concentrations in the boundary layer of the tropical forests indicate strong removal processes. Due to atmospheric supply of NO x by lightning, there is probably a large production of O3 in the free troposphere over the Amazon tropical forests. This is transported to the marine-free troposphere and to the forest boundary layer.  相似文献   

19.
In recent years, China has implemented several measures to improve air quality. The Beijing-Tianjin-Hebei(BTH)region is one area that has suffered from the most serious air pollution in China and has undergone huge changes in air quality in the past few years. How to scientifically assess these change processes remain the key issue in further improving the air quality over this region in the future. To evaluate the changes in major air pollutant emissions over this region, this paper employs ens...  相似文献   

20.
Dibromomethane (CH2Br2), a natural stratospheric ozone depleting substance, is mostly emitted from the ocean, but the relative importance of coastal (or macroalgae) and open ocean emissions is unknown. We made long-term high-frequency measurements of CH2Br2 concentrations at two remote coastal sites in Japan, on the subtropical Hateruma Island (poor in macroalgae) and at Cape Ochiishi (rich in macroalgae). CH2Br2 concentrations at Hateruma showed prominent seasonal variation, being lower in summer (around 0.94 ppt) than in winter (around 1.23 ppt). In contrast, CH2Br2 concentrations at Ochiishi were highly variable, often exceeding 2 ppt in the summer but with minimum baseline concentrations close to those from Hateruma; in the winter the concentrations were almost constant at about 1.3 ppt. Analysis of the data suggested that (1) emissions from macroalgae were not likely to extend offshore, but instead were localized near the shore, (2) strong macroalgal emissions of CH2Br2 were almost limited to the summer, but it was not reflected in the seasonality of the baseline concentrations of CH2Br2 in the atmosphere, and therefore (3) macroalgal or coastal emissions of CH2Br2 in the temperate zone might have a rather limited contribution to the global CH2Br2 sources. These findings are especially important for the understanding of the tropospheric and stratospheric bromine budget.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号