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1.
Major ion concentrations and Sr isotope ratios ( 87Sr/ 86Sr) were measured in rainwater samples collected at an urban site in Beijing over a period of one year. The pH value and major ion concentrations of samples varied considerably, and about 50% of the rainwater studied here were acidic rain with pH values less than 5.0. Ca 2+ and NH 4+ were the dominant cations in rainwaters and their volume weighted mean (VWM) values were 608 μeq l ?1 (14–1781 μeq l ?1) and 186 μeq l ?1 (48–672 μeq l ?1), respectively. SO 42? was the predominant anion with VWM value of 316 μeq l ?1 (65–987 μeq l ?1), next was NO 3? with VWM value of 109 μeq l ?1 (30–382 μeq l ?1).Using Na as an indicator of marine origin, and Al for the terrestrial inputs, the proportions of sea salt and terrestrial elements were estimated from elemental ratios. More than 99% of Ca 2+ and 98% of SO 42? in rainwater samples are non-sea-salt origin. The 87Sr/ 86Sr ratios were used to characterize the different sources based on the data sets of this study and those from literatures. Such sources include sea salts ( 87Sr/ 86Sr~0.90917), soluble soil dust minerals originating from either local or the desert and loess areas (~0.7111), and anthropogenic sources (fertilizers, coal combustion and automobile exhausts). The high concentrations of alkaline ions (mainly Ca 2+) in Beijing atmosphere have played an important role to neutralize the acidity of rainwater. However, it is worth noting that there is a remarkable acidification trend of rainwater in Beijing recent years. 相似文献
2.
A highly sensitive technique for the measurement of atmospheric HONO and HNO 3 is reported. The technique is based on aqueous scrubbing using two coil samplers, followed by conversion of HNO 3 to nitrite, derivatization of nitrite to a highly light-absorbing azo dye with sulfanilamide (SA) and N-(1-naphthyl) ethylenediamine (NED), and high performance liquid chromatography (HPLC) analysis. HNO 3 concentration was obtained by the difference of the two channels. Two scrubbing solutions were used for sampling the two species: a 1-mM phosphate buffer solution (pH 7) for the measurement of HONO and a 180 mM NH 4Cl/NH 3 buffer solution (pH 8.5) for the measurement of HONO+HNO 3. The scrubbing solution flow rate was 0.24 ml min −1 and the gas sampling flow rate was 2 l min −1. HNO 3 in the NH 4Cl/NH 3 buffer solution was quantitatively reduced to nitrite along an on-line 0.8-cm Cd reductor column. Nitrite in both channels was derivatized with 2 mM SA and 0.2 mM NED in 25 mM HCl. Quantitative derivatization was achieved within 5 min at 55°C. The azo dye derivative was then separated from the SA/NED reagent by reversed-phase HPLC and detected with a UV-vis detector at 540 nm. With an on-line SEP-PAK C-18 cartridge for the reagent purification, the method detection limit is estimated to be better than 1 pptv for HONO and about 20 pptv for HNO 3. The sample integration time was about 2 min and the sampling frequency is every 10 min. Data collected in downtown Albany and Whiteface Mountain, NY, are shown as examples of applications of this technique in both urban and remote clean environments. 相似文献
3.
A fractured sandstone aquifer at an industrial site is contaminated with trichloroethene to depths greater than 244 m. Field data indicate that trichloroethene is undergoing reduction to cis-1,2-dichloroethene (cDCE); vinyl chloride and ethene are present at much lower concentrations. Transformation of cDCE by pathways other than reductive dechlorination (abiotic and/or biotic) is of interest. Pyrite, which has been linked to abiotic transformation of chlorinated ethenes, is present at varying levels in the sandstone. To evaluate the possible role of pyrite in transforming cDCE, microcosms were prepared with groundwater, ~40 mg L ?1 cDCE + [ 14C]cDCE, and crushed solids (pure pyrite, pyrite-rich sandstone, or typical sandstone). During 120 d of incubation, the highest level of cDCE transformation occurred with typical sandstone (11–14% 14CO 2, 1–3% 14C-soluble products), followed by pyrite-rich sandstone (2–4% 14CO 2, 1% 14C-soluble products) and even lesser amounts with pure pyrite. These results indicate pyrite is not likely the mineral involved in transforming cDCE. A separate experiment using only typical sandstone compared the rate of cDCE transformation in non-sterilized, autoclaved, and propylene-oxide sterilized treatments, with pseudo-first order rate constants of 8.7, 5.4, and 1.0 yr ?1, respectively; however, transformation stopped after several months of incubation. Autoclaving increased the volume of pores, adsorption pore diameter, and surface area in comparison to non-sterilized typical sandstone. Nevertheless, autoclaving was less disruptive than chemical sterilization. The results provide definitive experimental evidence that cDCE undergoes anaerobic abiotic and biotic transformation in typical sandstone, with formation of CO 2 and soluble products. 相似文献
4.
Fine particulate matter (PM 2.5) was sampled at 5 Spanish locations during the European Community Respiratory Health Survey II (ECRHS II). In an attempt to identify and quantify PM 2.5 sources, source contribution analysis by principal component analysis (PCA) was performed on five datasets containing elemental composition of PM 2.5 analysed by ED-XRF. A total of 4–5 factors were identified at each site, three of them being common to all sites (interpreted as traffic, mineral and secondary aerosols) whereas industrial sources were site-specific. Sea-salt was identified as independent source at all coastal locations except for Barcelona (where it was clustered with secondary aerosols). Despite their typically dominant coarse grain-size distribution, mineral and marine aerosols were clearly observed in PM 2.5. Multi-linear regression analysis (MLRA) was applied to the data, showing that traffic was the main source of PM 2.5 at the five sites (39–53% of PM 2.5, 5.1–12.0 μg m −3), while regional-scale secondary aerosols accounted for 14–34% of PM 2.5 (2.6–4.5 μg m −3), mineral matter for 13–31% (2.4–4.6 μg m −3) and sea-salt made up 3–7% of the PM 2.5 mass (0.4–1.3 μg m −3). Consequently, despite regional and climatic variability throughout Spain, the same four main PM 2.5 emission sources were identified at all the study sites and the differences between the relative contributions of each of these sources varied at most 20%. This would corroborate PM 2.5 as a useful parameter for health studies and environmental policy-making, owing to the fact that it is not as subject to the influence of micro-sitting as other parameters such as PM 10. African dust inputs were observed in the mineral source, adding on average 4–11 μg m −3 to the PM 2.5 daily mean during dust outbreaks. On average, levels of Al, Si, Ti and Fe during African episodes were higher by a factor of 2–8 with respect to non-African days, whereas levels of local pollutants (absorption coefficient, S, Pb, Cl) showed smaller variations (factor of 0.5–2). 相似文献
5.
The kinetics of two structurally similar unsaturated alcohols, 3-butene-2-ol and 2-methyl-3-butene-2-ol (MBO232), with Cl atoms have been investigated for the first time, as a function of temperature using a relative method. As far as we know, the present work also provides the first value for 3-buten-2-ol. The coefficient at room temperature was also obtained for 2-propene-1-ol (allyl alcohol). The reactions were investigated using a 400 L Teflon reaction chamber coupled with gas chromatograph-coupled with flame-ionization detection (GC-FID) detection. The experiments were performed at atmospheric pressure and at temperatures between 256 and 298 K in air or nitrogen as the bath gas. The obtained kinetic data were used to derive the Arrhenius expressions, kMBO232=(2.83±2.50)×10 −14 exp (2670±249)/ T, k3-buten-2-ol=(0.65±1.60)×10 −15 exp (3656±695)/ T (in units of cm 3 molecule −1 s −1). Finally, results and atmospheric implications are discussed and compared with the reactivity with OH and NO 3 radicals. 相似文献
6.
Recent research interest has been focused on road dust resuspension as one of the major sources of atmospheric particulate matter in an urban environment. Given the dearth of studies on the variability of the PM 10 fraction of road deposited sediments, our understanding of the main factors controlling this pollutant is incomplete. In the present study a new sampling methodology was devised and applied to collect PM 10 deposited mass from 1 m 2 of road pavement. PM 10 road dust fraction was sampled directly from active traffic lanes at 23 sampling sites during a campaign in Barcelona (Spain) in June 2007. The aim of the study was to gain more insight into the variability of mass and chemistry of road dust in different urban environments, such as the city centre, ring roads, and locations nearby demolition/construction sites. The city centre showed values of PM 10 road dust within a range of 3–23 mg m ?2, whereas levels reached 24–80 mg m ?2 in locations affected by transport of uncovered heavy trucks. The largest dust loads were measured in the proximity of demolition/construction sites and the harbor entry with values up to 328 mg m ?2.The city centre road dust profiles (%) were enriched in OC, EC, Fe, S, Cu, Zn, Mn, Cr, Sb, Sn, Mo, Zr, Hf, Ge, Ba, Pb, Bi, SO 42?, NO 3?, Cl ? and NH 4+, but several crustal components such as Ca, Ti, Na, and Mg were also considerably concentrated. Locations affected by construction and demolition activities had high levels of crustal components such as Ca, Li, Sc, Sr, Rb and also As whereas ring roads, characterized by a higher load of uncovered heavy trucks showed an intermediate composition.Levels of PM 10 components per area were also evaluated to quantify the resuspendable amount of each element from 1 m 2. In the inner city environment mean values of 1363 μg Ca m ?2, 816 μg OC m ?2, 239 μg EC m ?2, 13 μg Cu m ?2, 12 μg Zn m ?2, 1.9 μg Sb m ?2 and 2.0 μg Pb m ?2, in PM 10 in all cases, were registered.Moreover the deposited PM load at demolition/construction sites acts as a reservoir or trap for traffic-related particles, which gives rise to large amounts of hazardous pollutants, available for resuspension. 相似文献
7.
Chemical surveys of snow were carried out in the upper reaches of the Kunnes River, a tributary of the Yili River in East Tienshan Mountains, China. Some surprisingly high values of sodium and potassium (K ++Na +) ranging from 4.44 to 8.99 mg/l compared with other data from neighboring areas are detected. Moreover, some relative high values of SO 42− with mean concentration 15.8 mg/l for new snow and 14.40 mg/l for deposited snow, ranging from 10.43 to 23.71 mg/l are also found. Therefore, it is inferred that the sodium and potassium (K ++Na +) are in the forms of sulfate and that the sources of the sulfate are deserts and some dried lakes in Central Asia. It is also found that there is obviously spatial variation of ions such as K ++Na +, Ca 2+, SO 42− and HCO 3−. The concentrations of K ++Na + and SO 42−, and that of Ca 2+ and HCO 3− have similar spatial pattern. The temporal pattern of ion concentration of new snow is considered to be mainly controlled by the depth and area of snow cover in the study area and in the areas to the west. 相似文献
8.
Aromatic hydrocarbons are important constituents of vehicle exhaust and of non-methane volatile organic compounds in ambient air in urban areas. It has recently been proposed that dealkylation is a significant pathway for the OH radical-initiated reactions, leading to the formation of phenolic compounds and/or oxepins (Noda, J., Volkamer, R., Molina, M.J., 2009. Dealkylation of alkylbenzenes: a significant pathway in the toluene, o-, m-, and p-xylene + OH reaction. Journal of Physical Chemistry A 113, 9658–9666.). We have investigated the formation of cresols from the reactions of OH radicals with m-xylene and p-cymene, and obtain upper limits of <1% for formation of each cresol isomer from OH + m-xylene and <2% for formation of each cresol isomer from OH + p-cymene. In addition, we have measured the formation yield of 4-methylacetophenone (the major product formed subsequent to H-atom abstraction from the CH(CH 3) 2 group) in the OH + p-cymene reaction to be 14.8 ± 3.2%, and estimate that H-atom abstraction from the CH 3 and CH(CH 3) 2 groups in p-cymene accounts for 20 ± 4% of the overall OH radical reaction. We also used a relative rate technique to measure the rate constant for the reaction of OH radicals with 4-methylacetophenone to be (4.50 ± 0.43) × 10 ?12 cm 3 molecule ?1 s ?1 at 297 ± 2 K. 相似文献
9.
The interaction of NO 2 on carbonaceous aerosol particles in an NO 2 concentration range relevant for the troposphere was studied. The adsorption as a function of NO 2 concentration (2.5–65 ppb) was investigated along with the dependence on time (1–600 s) and particle concentration. The results exhibit a zero-order process in NO 2 for the chemisorption over the measured time and concentration range. The results suggest that the chemisorption reaction is limited by a rapidly established steady-state coverage of a precursor in the form of reversibly adsorbed NO 2 which seems to be constant over the whole investigated NO 2 concentration range. Within the first 20 s, a chemisorption rate of 2.5×10 11 molecules cm -2 s -1 was calculated. To estimate a saturation value for the NO 2 adsorption on carbonaceous aerosol particles, bulk experiments were performed where the aerosol was deposited on a filter before exposure to NO 2. This gives a lower limit for the total NO 2 adsorption of about 1×10 14 molecules cm -2 of particle surface area. The measurements show that the concept of the often used sticking coefficient γ (i.e. the number of adsorbed molecules per number of the total gas–surface collisions) is not a useful parameter to describe the chemisorption of NO 2 at low ppb concentration on such complex surfaces as carbonaceous aerosol particles. 相似文献
10.
Ammonia-nitrogen flux (NH 3-N=(14/17)NH 3) was determined from six anaerobic swine waste storage and treatment lagoons (primary, secondary, and tertiary) using the dynamic chamber system. Measurements occurred during the fall of 1998 through the early spring of 1999, and each lagoon was examined for approximately one week. Analysis of flux variation was made with respect to lagoon surface water temperature (∼15 cm below the surface), lagoon water pH, total aqueous phase NH x(=NH 3+NH 4+) concentration, and total Kjeldahl nitrogen (TKN). Average lagoon temperatures (across all six lagoons) ranged from approximately 10.3 to 23.3 °C. The pH ranged in value from 6.8 to 8.1. Aqueous NH x concentration ranged from 37 to 909 mg N l −1, and TKN varied from 87 to 950 mg N l −1. Fluxes were the largest at the primary lagoon in Kenansville, NC (March 1999) with an average value of 120.3 μg N m −2 min −1, and smallest at the tertiary lagoon in Rocky Mount, NC (November 1998) at 40.7 μg N m −2 min −1. Emission rates were found to be correlated with both surface lagoon water temperature and aqueous NH x concentration. The NH 3-N flux may be modeled as ln(NH 3-N flux)=1.0788+0.0406 TL+0.0015([NH x]) ( R2=0.74), where NH 3-N flux is the ammonia flux from the lagoon surface in μg N m −2 min −1, TL is the lagoon surface water temperature in °C, and [NH x] is the total ammonia-nitrogen concentration in mg N l −1. 相似文献
11.
Long-range transport of mineral dust such as Yellow sand (YS) is not restricted to the springtime periods in Northeast Asia. A YS phenomenon was observed during 25–27 January 1999, which was a remarkably distinctive episode in the occurrence time and intensity that had ever observed in the wintertime in Korea. This YS event was traced to be originated from the arid region of central and eastern Asia; the Gobi desert and Loess plateau. The traveling speed of the dust storm was found to be about 70 km h −1 with it's horizontal size of larger than the whole Korean peninsula during this episode. Aerosol mass loadings changed by an order of magnitude within a few hours. The dominant ion components were SO 42−, NO 3−, Ca 2+ and Na + during the passage of YS. The mode diameter of these compounds of YS was around 4 μm, compared to 0.4–0.9 μm after the passage of YS. SO 42− and NO 3− concentrations were found to be well correlated with Ca 2+ concentration in the coarse mode during the YS event, whereas they were well correlated with NH 4+ concentration during the non-YS period, indicating a significant amount of SO 42− and NO 3− formations on the Ca 2+-rich coarse aerosol during the long-range transport of YS. 相似文献
12.
Micrometeorological flux-gradient and nocturnal boundary layer methods were combined with Fourier transform infrared (FTIR) spectroscopy for high-precision trace gas analysis to measure fluxes of the trace gases CO 2, CH 4 and N 2O between agricultural fields and the atmosphere. The FTIR measurements were fully automated and routinely obtained a precision of 0.1–0.2% for several weeks during a measurement campaign in October 1995. In flux-gradient measurements, vertical profiles of the trace gases were measured every 30 min from the ground to 22 m. When combined with independent micrometeorological measurements of water vapour fluxes, trace gas fluxes from the underlying surface could be determined. In the nocturnal boundary layer method the rate of change in mass storage in the 0–22 m layer was combined with fluxes measured at 22 m to estimate surface fluxes. Daytime fluxes for CO 2 were −0.78±0.40 (1 σ) mg CO 2 m −2 s −1. Daytime fluxes of N 2O and CH 4 were very small and difficult to measure reliably using the flux-gradient technique, despite the high precision of the concentration measurements. Mean daytime flux for N 2O was 17±48 ng N m −2 s −1, while the corresponding flux for CH 4 was 47±410 ng CH 4 m −2 s −1. The mean nighttime flux of CO 2 estimated using the nocturnal boundary layer method was +0.15±0.05 mg CO 2 m −2 s −1, in good agreement with chamber measurements of respiration rates. Nighttime fluxes of CH 4 and N 2O from the nocturnal boundary layer method were 109±69 ng CH 4 m −2 s −1 and 2±3.2 ng N m −2 s −1, respectively, in good agreement with chamber measurements and inventory estimates based on the sheep and cattle stocking rates in the region. The suitability of FTIR-based methods for long term monitoring of spatially and temporally averaged flux measurements is discussed. 相似文献
13.
A radiation fog physics, gas- and aqueous-phase chemistry model is evaluated against measurements in three sites in the San Joaquin Valley of California (SJV) during the winter of 1995. The measurements include for the first time vertically resolved fog chemical composition measurements. Overall the model is successful in reproducing the fog dynamics as well as the temporal and spatial variability of the fog composition (pH, sulfate, nitrate, and ammonium concentrations) in the area. Sulfate production in the fog layer is relatively slow (1–4 μg m −3 per fog episode) compared to the episodes in the early 1980s because of the low SO 2 concentrations in the area and the lack of oxidants inside the fog layer. Sulfate production inside the fog layer is limited by the availability of oxidants in the urban areas of the valley and by SO 2 in the more remote areas. Nitrate is produced in the rural areas of the valley by the heterogeneous reaction of N 2O 5 on fog droplets, but this reaction is of secondary importance for the more polluted urban areas. The gas-phase production of HNO 3 during the daytime is sufficient to balance the nitrate removed during the nighttime fog episodes. Entrainment of air from the layer above the fog provides another source of reactants for the fog layer. Wet removal is one of most important processes inside the fog layer in SJV. We estimate based on the three episodes investigated during IMS95 that a typical fog episode removes 500–2000 μg m −2 of sulfate, 2500–6500 μg m −2 of nitrate, and 2000–3500 μg m −2 of ammonium. For the winter SJV valley the net fog effect corresponds to reductions in ground ambient concentrations of 0.05–0.2 μg m −3 for sulfate, 3–6 μg m −3 for total nitrate, and 1–3 μg m −3 for total ammonium. 相似文献
14.
The characteristics of ambient aerosols, affected by solar radiation, relative humidity, wind speed, wind direction, and gas–aerosol interaction, changed rapidly at different spatial and temporal scales. In Taipei Basin, dense traffic emissions and sufficient solar radiation for typical summer days favored the formation of secondary aerosols. In winter, the air quality in Taipei Basin was usually affected by the Asian continental outflows due to the long-range transport of pollutants carried by the winter monsoon. The conventional filter-based method needs a long time for collecting aerosols and analyzing compositions, which cannot provide high time-resolution data to investigate aerosol sources, atmospheric transformation processes, and health effects. In this work, the in situ ion chromatograph (IC) system was developed to provide 15-min time-resolution data of nine soluble inorganic species (Cl −, NO 2−, NO 3−, SO 42−, Na +, NH 4+, K +, Mg 2+ and Ca 2+). Over 89% of all particles larger than approximately 0.056 μm were collected by the in situ IC system. The in situ IC system is estimated to have a limit of detection lower than 0.3 μg m −3 for the various ambient ionic components. Depending on the hourly measurements, the pollutant events with high aerosol concentrations in Taipei Basin were associated with the local traffic emission in rush hour, the accumulation of pollutants in the stagnant atmosphere, the emission of industrial pollutants from the nearby factories, the photochemical secondary aerosol formation, and the long-range transport of pollutants from Asian outflows. 相似文献
15.
The heterogeneous reactivity of nitrogen dioxide with pyrene and 1-nitropyrene (1NP) adsorbed on silica particles has been investigated using a fast-flow-tube in the absence of light. Reactants and products were extracted from particles using pressurised fluid extraction (PFE) and concentration measurements were performed using gas chromatography/mass spectrometry (GC/MS). The pseudo-first order rate constants were obtained from the fit of the experimental decay of particulate polycyclic compound concentrations versus reaction time. Experiments were performed at three different NO 2 concentrations and second order rate constants were calculated considering the oxidant concentration. The following rate constant values were obtained at room temperature: k(NO 2 + pyrene) = (9.3 ± 2.3) × 10 ?17 cm 3 molecule ?1 s ?1 and k(NO 2 + 1NP) = (6.2 ± 1.5) × 10 ?18 cm 3 molecule ?1 s ?1, showing that the reactivity of 1NP was slower by a factor of 15 than that of pyrene. 1NP was identified as the only NO 2-initiated oxidation product of pyrene and all the three dinitropyrenes were identified in the case of the 1NP reaction. The product quantification allowed showing that the kinetics of oxidation product formation was equal to that measured for parent compounds degradation, within uncertainties, confirming the validity of the reaction kinetics measurements. 相似文献
16.
The emission of isoprene has been studied from a forest of Abies Borisii-regis, a Mediterranean fir species previously thought to emit only monoterpenes. Emission studies from two independent enclosure experiments indicated a standardised isoprene emission rate of (18.4±3.8) μg g dry-weight−1 h −1, similar in magnitude to species such as eucalyptus and oak which are considered to be strong isoprene emitters. Isoprene emission depended strongly on both leaf temperature (2°C–34°C) and photosynthetically active radiation (PAR) below 250 μmol m −2 s −1, becoming saturated with respect to PAR above this value. The annual isoprene emission rate was estimated to be (132±29) kT yr −1 for those trees growing within Greece, comparable to current estimates of the total isoprene budget of Greece as a whole, and contributing significantly to regional ozone and carbon monoxide budgets. Monoterpene emission exhibited exponential temperature dependence, with 1,8-cineole, α-pinene, β-pinene and limonene forming the primary emissions. A standardised total monoterpene emission rate of (2.7±1.1) μg g dry-weight−1 h −1 was calculated, corresponding to an annual monoterpene emission rate of (24±12) kT yr −1. Research was conducted as part of the AEROBIC’97 (AEROsol formation from BIogenic organic Carbon) series of field campaigns. 相似文献
17.
Seawater, atmospheric dimethylsulfide (DMS) and aerosol compounds, potentially linked with DMS oxidation, such as methanesulfonic acid (MSA) and non-sea-salt sulfate (nss-SO 42?) were determined in the North Yellow Sea, China during July–August, 2006. The concentrations of seawater and atmospheric DMS ranged from 2.01 to 11.79 nmol l ?1 and from 1.68 to 8.26 nmol m ?3, with average values of 6.20 nmol l ?1 and 5.01 nmol m ?3, respectively. Owing to the appreciable concentration gradient, DMS accumulated in the surface water was transferred into the atmosphere, leading to a net sea-to-air flux of 6.87 μmol m ?2 d ?1 during summer. In the surface seawater, high DMS values corresponded well with the concurrent increases in chlorophyll a levels and a significant correlation was observed between integrated DMS and chlorophyll a concentrations. In addition, the concentrations of MSA and nss-SO 42? measured in the aerosol samples ranged from 0.012 to 0.079 μg m ?3 and from 3.82 to 11.72 μg m ?3, with average values of 0.039 and 7.40 μg m ?3, respectively. Based on the observed MSA, nss-SO 42? and their ratio, the relative biogenic sulfur contribution was estimated to range from 1.2% to 11.5%, implying the major contribution of anthropogenic source to sulfur budget in the study area. 相似文献
18.
The infrared spectrum of HCF 2OCF 2OCF 2CF 2OCF 2H (CAS# 188690-77-9) has been re-measured. The integrated absorption intensity over the range 1000–1500 cm ?1 measured in the present work is (6.65 ± 0.33) × 10 ?17 cm 2 molecule ?1 cm ?1 in 700 Torr of air at 296 K. The radiative efficiency of HCF 2OCF 2OCF 2CF 2OCF 2H is calculated to be 1.02 W m ?2 ppb ?1. The value reported in the 2007 Intergovernmental Panel on Climate Change (IPCC) report is approximately 35% larger reflecting what we believe to be an erroneously high value for the absorption strength of HCF 2OCF 2OCF 2CF 2OCF 2H adopted by the IPCC. 相似文献
19.
We utilized a multi-biomarker approach (Integrated Biomarker Response version 2, IBRv2) to investigate the scope and dispersion of groundwater contamination surrounding a rare earth mine tailings impoundment. Parameters of SD rat included in our IBRv2 analyses were glutathione levels, superoxide dismutase, catalase, and glutathione peroxidase activities, total anti-oxidative capacity, chromosome aberration, and micronucleus formation. The concentration of 20 pollutants including Cl?, SO4
2?, Na+, K+, Mg2+, Ca2+, TH, CODMn, As, Se, TDS, Be, Mn, Co, Ni, Cu, Zn, Mo, Cd, and Pb in the groundwater were also analyzed. The results of this study indicated that groundwater polluted by tailings impoundment leakage exhibited significant ecotoxicological effects. The selected biomarkers responded sensitively to groundwater pollution. Analyses showed a significant relationship between IBRv2 values and the Nemerow composite index. IBRv2 could serve as a sensitive ecotoxicological diagnosis method for assessing groundwater contamination in the vicinity of rare earth mine tailings. According to the trend of IBRv2 value and Nemerow composite index, the maximum diffusion distance of groundwater pollutants from rare earth mine tailings was approximately 5.7 km. 相似文献
20.
This study examined commuter’s exposure to respirable suspended particulate matters while commuting in public transportation modes. The survey was conducted between October 1999 and January 2000 in Hong Kong. A total of eight public transportation modes, that are bus, tram, public light bus, taxi, ferry, Kowloon–Canton Railway, Mass Transit Railway and Light Rail Transit, were selected in the study. They were grouped into four categories: (T1) railway transport; (T2) non-air-conditioned roadway transport; (T3) air-conditioned roadway transport and (T4) marine transport. Both PM 10 and PM 2.5 levels were investigated. The results indicate that the particulate level is greatly affected by the mode of transport as well as the ventilation system of the transport. The overall average PM 10 concentration level in T2 (147 μg m −3) is the highest and is followed by T4 (81 μg m −3) and T3 (65 μg m −3). The PM 10 level in T1 (50 μg m −3) is the lowest. Notably, the commuter exposure in tram (175 μg m −3) is the highest among all the monitored commuting modes. Commuting modes such as railway and air-conditioned vehicle are recommended as a substitute for non-air-conditioned vehicle. The PM 2.5 to PM 10 ratio in transports ranged from 63% to 78%. Higher PM 2.5 to PM 10 ratio is found in vehicles with air-conditioning system. For the double deck vehicle, higher PM 10 level has resulted in the lower deck. The average upper-deck to lower-deck PM 10 ratio is 0.836, 0.751 and 0.738 in air-conditioned bus, non-air-conditioned bus and non-air-conditioned tram, respectively. Typical concentration profiles in different transports are also presented. 相似文献
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