共查询到20条相似文献,搜索用时 418 毫秒
1.
Both aerosol and rainwater samples were collected and analyzed for ionic species at a coastal site in Southeast Asia over
a period of 9 months (January–September 2006) covering different monsoons. In general, the occurrence and distribution of
ionic species showed a distinct seasonal variation in response to changes in air mass origins. Real-time physical characterization
of aerosol particles during rain events showed changes in particle number distributions which were used to assess particle
removal processes associated with precipitation, or scavenging. The mean scavenging coefficients for particles in the range
10–500 nm and 500–10 μm were 7.0 × 10 −5 ± 2.8 × 10 −5 s −1 and 1.9 × 10 −4 ± 1.6 × 10 −5 s −1, respectively. A critical analysis of the scavenging coefficients obtained from this study suggested that the wet removal
of aerosol particles was greatly influenced by rain intensity, and was particle size-dependent as well. The scavenging ratios,
another parameter used to characterize particle removal processes by precipitation, for NH 4
+, Cl −, SO 4
2−, and NO 3
− were found to be higher than those of Na +, K +, and Ca 2+ of oceanic and crustal origins. This enrichment implied that gaseous species NH 3, HCl, and HNO 3 could also be washed out readily. These additional sources of ions in precipitation presumably counter-balanced the dilution
effect caused by high total precipitation volume in the marine and tropical area. 相似文献
2.
The chemical composition, as well as the sources contributing to rainwater chemistry have been determined at Skukuza, in the Kruger National Park, South Africa. Major inorganic and organic ions were determined in 93 rainwater samples collected using an automated wet-only sampler from July 1999 to June 2002. The results indicate that the rain is acidic and the averaged precipitation pH was 4.72. This acidity results from a mixture of mineral acids (82%, of which 50% is H 2SO 4) and organic acids (18%). Most of the H 2SO 4 component can be attributed to the emissions of sulphur dioxide from the industrial region on the Highveld. The wet deposition of S and N is 5.9 kgS⋅ha −1⋅yr −1 and 2.8 kgN⋅ha −1⋅yr −1, respectively. The N deposition was mainly in the form of NH 4
+. Terrigenous, sea salt component, nitrogenous and anthropogenic pollutants have been identified as potential sources of chemical components in rainwater. The results are compared to observations from other African regions. 相似文献
3.
The present study comprehensively reports the simultaneous measurement of wet deposition of total inorganic nitrogen (TIN; which is the sum of the NH4+-N and NO3?-N) at three different sites in Nr emission hotspot of Indo-Gangetic plain (IGP) over a year-long temporal scale from October 2017 to September 2018. At rural Meetli (MTL) site, urban Baraut (BRT) site and industrial Loni (LNI) site, the annual wet deposition of NH4+-N was estimated as 21.87, 19.48 and 7.43 kg N ha?1 yr?1, respectively; the annual wet deposition NO3?-N was estimated as 12.96, 12.17 and 4.44 kg N ha?1 yr?1, respectively; and the annual wet deposition of TIN was estimated as 34.83, 31.64 and 11.87 kg N ha?1 yr?1, respectively. NH4+-N was dominantly contributing species in annual, monsoon and non-monsoon-time wet deposition of TIN at all sites. The spatial gradient (variability) in percent contribution of NH4+ to total annual volume-weighted mean (VWM) concentration of all analyte ions was observed as MTL (43.23%)?>?BRT (37.90%)?>?LNI (30%). On the other hand, the spatial gradient in percent contribution of NO3? to total annual VWM concentration of all analyte ions was observed as MTL (7.45%)?>?BRT (6.89%)?>?LNI (5.32%). The extremely narrow range of NH4+-N/NO3?-N ratios (ranging from 1.60 at BRT site to 1.69 at LNI site) showed the approximately equal relative abundance of oxidized and reduced nitrogen (N) deposition across all sites. Inferences from enrichment factor analysis, principal component analysis and Pearson’s correlation coefficient analysis suggested that across all sites, virtually all NH4+-N and NO3?-N depositions were originated anthropogenically. The annual wet deposition of TIN measured in this study showed?≥?6865%,?≥?6228% and?≥?2274% increment than the natural N deposition rate at MTL, BRT and LNI site, respectively. These empirically measured annual wet depositions of TIN also emanated theoretical transgression of critical N load threshold across all sites therefore signifying probable undermining of long-term elastic stability and resilience of ecosystems against stressor in the study domain. 相似文献
4.
A comprehensive study on the chemical compositions of rainwater was carried out from June 2007 to December 2008 in Guiyang,
a city located on the acid rain control zone of southwest China. All samples were analyzed for pH, major anions (F −, Cl −, NO 3−, SO 42−), major cations (K +, Na +, Ca 2+, Mg 2+, NH 4+), Sr 2+ and Sr isotope. The pH increase is due to the result of neutralization caused by the alkaline dust which contain large amount
of CaCO 3. It was observed that Ca 2+ was the most abundant cation with a volume-weighted mean (VWM) value of 217.6 μeq/L (52.7–1928 μeq/L), accounting for 66%
(39%–88%) of the total cations. SO 42− was the most abundant anion with VWM value of 237.8 μeq/L (49.6-1643 μeq/L). SO 42− and NO 3− were dominant among the anions, accounting for 66%–97% of the total measured anions. The Sr concentrations vary from 0.01
to 0.92 μmol/L, and strontium isotopic ratios vary in the range of 0.707684–0.710094, with an average of 0.708092. The elements
ratios and the 87Sr/ 86Sr ratios showed that the solutes of rainwater mainly come from weathering of carbonate and secondary dust input. Moreover,
urbanization results in the calcium-rich dust increased and the high concentrations of alkaline ions (mainly Ca 2+) have played an important role to neutralize the acidity of rainwater, leading to the increase of arithmetic pH mean value
by 0.5 units since 2002. It is worth noting that the emission of SO 2 and NO x from the automobile exhaust is increasing and is becoming another important precursor of acid rain now. 相似文献
5.
Concentrations of manganese in 56 rain events in Wilmington, NC, USA rainwater from April 1, 2005 to March 31, 2006 were 11 ± 3 nM
for dissolved Mn and 1.2 ± 0.4 nM for particulate Mn. Concentrations of both forms of Mn were higher in terrestrial storms
relative to marine events. This observation along with the positive correlation of Mn with pollutant indicators suggests anthropogenic
inputs to rain at this location, as has been observed at other locations. The ratio of Mn part/Mn diss was threefold larger in summer relative to winter rain, which matched the increase of particulate to dissolved Fe in rainwater
suggesting influence of Saharan dust during the summer. Like Fe in rain, Mn undergoes photoreduction in rainwater, which has
also been shown to be important in Mn cycling in seawater. The flux of Mn removed from the atmosphere via wet deposition is
1.5 × 10 −5 moles m −2 yr −1 at this location, which is approximately twice the flux reported from two rainwater studies conducted in the early 1980s
on Bermuda. Atmospheric input of Mn to the oceans is important because Mn like Fe is an essential and potentially limiting
nutrient. Experiments mixing authentic rainwater and seawater demonstrate that rainwater dissolved Mn does not rapidly precipitate
in seawater suggesting wet deposition is an important source of soluble, stable Mn to surface seawater. 相似文献
6.
Continuous weekly monitoring on the concentration of gases and aerosols in urban ambient air by a four-stage filter-pack method
was carried out for 7 years in order to study not only the acid-base balance of acid-related (HNO 3, NO 3
−, and non-sea-salt-(nss-)SO 4
2−) and alkali-related (NH 3, NH 4
+, and nss-Ca 2+) chemical species but also its influence on the acidification of precipitation. The concentrations of the total nitrate (=
NO 3− + HNO 3) and nss-SO 42− showed a similar seasonal variation: high in the summer and low in the winter. The total nitrate and nss-SO 42− accounted for 0.43 and 0.57 of the acid-related species, respectively, on an equivalent basis. The total ammonium (= NH 3 + NH 4+) accounted for more than 0.9 of the alkali-related species, except for a springtime nss-Ca 2+ episodic peak. The alkali-related species were generally overabundant compared with the acid-related species in the HNO 3-NO 3−-nss-SO 42−-NH 3-NH 4+-nss-Ca 2+ system. The alkali-rich distribution was especially pronounced in the winter, but the acid-related species was comparable
to the alkali-related species in the summer, which was attributed to the larger H + deposition by precipitation in the summer. This study can provide a methodology to associate survey results obtained by a
filter-pack method with those of precipitation. 相似文献
7.
Rainwater was collected from 129 rain events between February 2002 and August 2003 and analyzed for ammonium (NH 4+), nitrate (NO 3−), organic nitrogen (ON) and free amino acids (AA). Inorganic nitrogen (NO 3− + NH 4+) was the dominant form of N representing 85% of total nitrogen based on volume-weighted averages. The remainder of the N
occurred as organic nitrogen species of which free amino acids contribute approximately 17%. A significant, and in some cases
the majority (> 75%), of the remaining ON could be accounted for by macromolecular uncharacterized humic like substances.
This has important ramifications with respect to the long range transport of atmospheric ON because humic materials are recalcitrant
and therefore may travel long distances from their source. There was a distinct seasonality to the N speciation data with
maximum concentrations of NH 4+, ON and AA occurring in the spring. Air-mass back trajectory analysis indicates there is a strong anthropogenic component
to the NO 3−, NH 4+ and AA signal but not ON. There was a strong positive correlation between amino acid concentrations and ammonium which suggests
they have similar sources and sinks in rainwater. Finally, large episodic additions of NH 4+ and AA during tropical events could significantly impact short term bioavailable N budgets in estuaries impacted by these
storms. Approximately three times as much NH 4+ and AA were deposited during Hurricane Isabel (317 μ moles ⋅ m −2 and 84 μ moles ⋅ m −2 respectively) compared to the mean impact of average summertime rain events at this location. 相似文献
8.
Size-segregated aerosol particles were collected using a high volume MOUDI sampler at a coastal urban site in Xiamen Bay, China, from March 2018 to June 2020 to examine the seasonal characteristics of aerosol and water-soluble inorganic ions (WSIIs) and the dry deposition of nitrogen species. During the study period, the annual average concentrations of PM1, PM2.5, PM10, and TSP were 14.8?±?5.6, 21.1?±?9.0, 35.4?±?14.2 μg m?3, and 45.2?±?21.3 μg m?3, respectively. The seasonal variations of aerosol concentrations were impacted by the monsoon with the lowest value in summer and the higher values in other seasons. For WSIIs, the annual average concentrations were 6.3?±?3.3, 2.1?±?1.2, 3.3?±?1.5, and 1.6?±?0.8 μg m?3 in PM1, PM1-2.5, PM2.5–10, and PM>10, respectively. In addition, pronounced seasonal variations of WSIIs in PM1 and PM1-2.5 were observed, with the highest concentration in spring-winter and the lowest in summer. The size distribution showed that SO42?, NH4+ and K+ were consistently present in the submicron particles while Ca2+, Mg2+, Na+ and Cl? mainly accumulated in the size range of 2.5–10 μm, reflecting their different dominant sources. In spring, fall and winter, a bimodal distribution of NO3? was observed with one peak at 2.5–10 μm and another peak at 0.44–1 μm. In summer, however, the fine mode peak disappeared, likely due to the unfavorable conditions for the formation of NH4NO3. For NH4+ and SO42?, their dominant peak at 0.25–0.44 μm in summer and fall shifted to 0.44–1 μm in spring and winter. Although the concentration of NO3–N was lower than NH4–N, the dry deposition flux of NO3–N (35.77?±?24.49 μmol N m?2 d?1) was much higher than that of NH4–N (10.95?±?11.89 μmol N m?2 d?1), mainly due to the larger deposition velocities of NO3–N. The contribution of sea-salt particles to the total particulate inorganic N deposition was estimated to be 23.9—52.8%. Dry deposition of particulate inorganic N accounted for 0.95% of other terrestrial N influxes. The annual total N deposition can create a new productivity of 3.55 mgC m?2 d?1, accounting for 1.3–4.7% of the primary productivity in Xiamen Bay. In light of these results, atmospheric N deposition could have a significant influence on biogeochemistry cycle of nutrients with respect to projected increase of anthropogenic emissions from mobile sources in coastal region. 相似文献
9.
We assessed the rainwater chemistry, the potential sources of its main inorganic components and bulk atmospheric deposition in a rural tropical semiarid region in the Brazilian Caatinga. Rainfall samples were collected during two wet seasons, one during an extremely dry year (2012) and one during a year with normal rainfall (2013). According to measurements of the main inorganic ions in the rainwater (H +, Na +, NH 4 +, K +, Ca 2+, Mg 2+, Cl ?, NO 3 ?, and SO 4 2?), no differences were observed in the total ionic charge between the two investigated wet seasons. However, Ca 2+, K +, NH 4 + and NO 3 ? were significant higher in the wetter year ( p < 0.05) which was attributed to anthropogenic activities, such as organic fertilizer applications. The total ionic contents of the rainwater suggested a dominant marine contribution, accounting for 76 % and 58 % of the rainwater in 2012 and 2013, respectively. The sum of the non-sea-salt fractions of Cl ?, SO 4 2?, Mg 2+, Ca 2+ and K + were 19 % and 33 % in 2012 and 2013, and the nitrogenous compounds accounted for 2.8 % and 6.0 % of the total ionic contents in 2012 and 2013, respectively. The ionic ratios suggested that Mg 2+ was probably the main neutralizing constituent of rainwater acidity, followed by Ca 2+. We observed a low bulk atmospheric deposition of all major rainwater ions during both wet seasons. Regarding nitrogen deposition, we estimated slightly lower annual inputs than previous global estimates. Our findings contribute to the understanding of rainfall chemistry in northeastern Brazil by providing baseline information for a previously unstudied tropical semiarid ecosystem. 相似文献
10.
Secondary aerosol formation was studied at Allahabad in the Indo-Gangetic region during a field campaign called Land Campaign-II
in December 2004 (northern winter). Regional source locations of the ionic species in PM 10 were identified by using Potential Source Contribution Function (PSCF analysis). On an average, the concentration of water
soluble inorganic ions (sum of anions and cations) was 63.2 μgm −3. Amongst the water soluble ions, average NO 3− concentration was the highest (25.0 μgm −3) followed by SO 42− (15.8 μgm −3) and NH 4+ (13.8 μgm −3) concentrations. These species, contributed 87% of the total mass of water soluble species, indicating that most of the water
soluble PM 10 was composed of NH 4NO 3 and (NH 4) 2SO 4/NH 4HSO 4 or (NH 4) 3H(SO 4) 2 particles. Further, the concentrations of SO 42−, NO 3−, and NH4 + aerosols increased at high relative humidity levels up to the deliquescence point (∼63% RH) for salts of these species suggesting
that high humidity levels favor the conversion and partitioning of gaseous SO 2, NO x, and NH 3 to their aerosol phase. Additionally, lowering of ambient temperature as the winter progressed also resulted in an increase
of NO 3− and NH 4+ concentrations, probably due to the semi volatile nature of ammonium nitrate. PSCF analysis identified regions along the
Indo-Gangetic Plain (IGP) including Northern and Central Uttar Pradesh, Punjab, Haryana, Northern Pakistan, and parts of Rajasthan
as source regions of airborne nitrate. Similar source regions, along with Northeastern Madhya Pradesh were identified for
sulfate. 相似文献
11.
PM 10 samples were collected over three years at Monzenmachi, the Japan Sea coast, the Noto Peninsula, Ishikawa, Japan from January
17, 2001 to December 18, 2003, using a high volume air sampler with quartz filters. The concentrations of the water-soluble
inorganic ions in PM 10 were determined with using ion chromatography. By analyzing the characteristics of these, the evidences were found that the
Asian outflow had an obviously influence on the air quality at our study site. The results were as follows: the secondary
pollutants SO 42−, NO 3− and NH 4+ were the primary water-soluble inorganic ions at our study site. The monthly mean concentrations of SO 42−, NH 4+, NO 3− and Ca 2+ have prominent peak in spring due to the strong influence of the Asian continent outflow—these according to backward air
trajectory analysis, the maximum of which were 6.09 for nss-SO 42− in May, 2.87 for NO 3− and 0.68 μg m −3 for nss-Ca 2+ in April, respectively. Comparable to similar data reported from various points around East Asia, it had the characteristics
of a polluted coastal area at our study site. The concentration of nss-Ca 2+ in PM 10 drastically increased when the Asian dust invaded, the mean value during the Asian dust days(AD) was 0.86 μg m −3, about 4 times higher than those of normal days (NAD). Meanwhile, the mean concentrations of nss-SO 42−, NO 3− and NH 4+ in AD periods were higher than those in NAD periods which were 5.87, 1.76 and 1.82 μg m −3, respectively, it is due to the interaction between dust and secondary particles during the long-range transport of dust
storms. Finally, according to the source apportionment with positive matrix factorization (PMF) method in this study, the
major source profiles of PM 10 at our study site were categorized as (1) marine salt, (2) secondary sulfate, (3) secondary nitrate and (4) crustal source. 相似文献
12.
The kinetics of heterogeneous reactions of NO 2 with 17 polycyclic aromatic hydrocarbons (PAHs) adsorbed on laboratory generated kerosene soot surface was studied over the
temperature range (255–330) K in a low pressure flow reactor combined with an electron-impact mass spectrometer. The kinetics
of soot-bound PAH consumption due to their desorption and reaction with NO 2 were monitored using off-line HPLC measurements of their concentrations in soot samples as a function of reaction time, NO 2 concentrations in the gas phase being analyzed by mass spectrometer. No measurable decay of PAHs due to the reaction with
NO 2 was observed under experimental conditions of the study (maximum NO 2 concentration of 5.5 × 10 14 molecule cm −3 and reaction time of 45 min), which allowed to determine the upper limits of the first-order rate constants for the heterogeneous
reactions of 17 soot-bound PAHs with NO 2: k < 5.0 × 10 −5 s −1 (for most PAHs studied). Comparison of these results to previous studies carried on different carbonaceous substrates, showed
that heterogeneous reactivity of PAHs towards NO 2 is, probably, dependent on the substrate nature even for resembling, although different carbonaceous materials. Results show
that particulate PAHs degradation by NO 2 alone is of minor importance in the atmosphere 相似文献
13.
A partial balance of mineral N is given for the basins of two coastal rivers in a forest zone in the Ivory Coast. The dry and wet depositions on the basin surfaces is given for particulate matter (NO 3
–, NH 4
+). The quantity of mineral N washed away in the rivers is evaluated. The losses from leaching of the soils by rainwater are about 0.33 to 1.0% of the atmospheric depositions for NH 4
+–N and 2.2 to 5.8% for NO 3
––N. The yearly atmospheric input of N compounds to the ecosystem, about 1.4 g N m –2 y –1, is at least 14% of mineral N formed in the soils and is therefore quite significant. 相似文献
14.
Long-term measurements of ambient particulate matter less than 2.5 μm in diameter (PM 2.5) and its chemical compositions were performed at a rural site in Korea from December 2005 to August 2009. The average PM 2.5 concentration was 31 μg m −3 for the whole sampling period, and showed a slightly downward annual trend. The major components of PM 2.5 were organic carbon, SO 42−, NO 3−, and NH 4+, which accounted for 55 % of total PM 2.5 mass on average. For the top 10 % of PM 2.5 samples, anionic constituents and trace elements clearly increased while carbonaceous constituents and NH 4+ remained relatively constant. Both Asian dust and fog events clearly increased PM 2.5 concentrations, but affected its chemical composition differently. While trace elements significantly increased during Asian
dust events, NO 3−, NH 4+ and Cl were dramatically enhanced during fog events due to the formation of saturated or supersaturated salt solution. The
back-trajectory based model, PSCF (Potential Source Contribution Function) identified the major industrial areas in Eastern
China as the possible source areas for the high PM 2.5 concentrations at the sampling site. Using factor analysis, soil, combustion processes, non-metal manufacture, and secondary
PM 2.5 sources accounted for 77 % of the total explained variance. 相似文献
15.
In the present study, the wet and dry depositions of particulate NO 3−, SO 42−, Cl − and NH 4+ were measured using a wet/dry sampler as a surrogate surface. Gas phase compounds of nitrogen, sulfur and chloride (HNO 3, NH 3, SO 2 and HCl) were measured by an annular denuder system (ADS) equipped with a back up filter for the collection of particles with diameter ≤ 5 μm. Ambient concentrations of NO, NO 2 and SO 2 were also taken into consideration. Sampling was conducted at an urban site in the center of the city of Thessaloniki, northern Greece. The presence of the aerosol species was examined by cold/warm period and the possible compounds in dry deposits were also considered. Dry deposition fluxes were found to be well correlated with ambient particle concentrations in order to be used for the calculation of particle deposition velocity. Average particulate deposition velocities calculated were 0.36, 0.20, 0.20 and 0.10 cm s − 1 for Cl −, NO 3−, SO 42− and NH 4+, respectively. Total dry deposition fluxes (gas and particles) were estimated at 3.24 kg ha − 1 year − 1 for chloride (HCl + p-Cl), 9.97 kg ha − 1 year − 1 for nitrogen oxidized (NO + NO 2 + HNO 3 + p-NO 3), 5.32 kg ha − 1 year − 1 for nitrogen reduced (NH 3 + p-NH 4) and 15.77 kg ha − 1 year − 1 for sulfur (SO 2 + p-SO 4). 70–90% total dry deposition was due to gaseous species deposition. The contribution of dry deposition to the total (wet + dry) was at the level of 60–70% for sulfur and nitrogen (oxidized and reduced), whereas dry chloride deposition contributed 35% to the total. The dry-to-wet deposition ratio of all the studied species was found to be significantly associated with the precipitation amount, with nitrogen species being better and higher correlated. Wet, dry and total depositions measured in Thessaloniki, were compared with other countries of Europe, US and Asia. 相似文献
16.
The present study investigates the chemical composition of wet atmospheric precipitation samples on a daily and an intra-event
timescales in Opme, an experimental meteorological station located near Clermont-Ferrand, France. The samples have been collected
from November 2005 to October 2007. A total of 217 rainwater samples, integrated for 24 h, were collected and analyzed for
pH, conductivity, Na +, K +, Mg 2+, NH 4+, Ca 2+, Cl −, NO 3− , SO 42− , PO 43− and HCO 3−. The composition of the rainwater collected appeared to be controlled by the following potential sources: neutralisation
process (association among calcium, ammonium with nitrate and sulphate), marine and terrestrial sources. In order to determine
the role of long-range transport, the integrated events were classified according to four origins of air-masses: (1) West,
(2) North and East, (3) South including Iberian and Italian Peninsulae and (4) local. This analysis allows identifying the
source areas of the different association of elements defined. Although calcium is always dominant, total content of rainfall
is variable and neutralisation process can be more or less efficient and specific. Rainout (long-range transport) and washout
(below-cloud scavenging) were investigated through intra-event measurements of chemical species. Four rain-events have been
selected according to the four classes of origins of air-masses. It appears that the first fractions are responsible for an
important part of the chemical content of the whole event. Terrestrial species, locally emitted, induce the neutralisation
process of acid species. Local meteorological conditions, such as wind’s speed and direction, play an important role as they
could provoke recharges of the below cloud air column during the event. 相似文献
17.
Evaluating trends over time (nonparametric Mann–Kendall test) for 18 water chemical variables from 79 reference lakes, distributed
all over Sweden, during spring since 1984 showed most significant trends for atmospheric deposition driven sulfate (SO 4) concentrations. The decrease in SO 4 concentrations was on average 2.7 times higher at lower (56°N to 59°N) than at higher latitudes (60°N to 68°N). This large
difference in the rate of change between lower and higher latitudes could not solely be explained by atmospheric deposition
as the rates of change in SO 4 wet deposition differed by a factor of only 1.5 between lower and higher latitudes. Significantly higher rates of change
at lower than at higher latitudes are known from the timing of lake ice breakup, a typical climate change indicator. The rates
of change in the timing of lake ice breakup differed by a factor of 2.3 between lower and higher latitudes. Other water chemical
variables showing significantly higher rates of change at lower than at higher latitudes were water color (a factor of 3.5),
calcium (a factor of 2.9), magnesium (a factor of 5.5) and conductivity (a factor of 5.9). The rates of change of all these
variables were strongly related to the rates of change in the timing of lake ice breakup along a latitudinal gradient ( R
2 = 0.41–0.78, p < 0.05), suggesting that climatic changes can accelerate atmospheric driven changes at especially lower latitudes. This acceleration
will result in more heterogeneous lake ecosystems along a latitudinal gradient. 相似文献
18.
The results of a 8 year survey of wet and dry depositions collected in Bologna (Northern Italy) are presented and discussed:
monthly fluxes of the main ions (hydrogen, sodium, potassium, calcium, magnesium, ammoniacal and nitrate nitrogen, sulphate
and chloride) have been registered and statistically discussed. The trend of hydrogen ion, whose largest correlation in the
global deposition was found with sulphate, is clearly downwards, with peaks mainly in winter months. By means of a data factor
analysis, three main sources to explain the variability of the deposition chemistry were recognized: an anthropogenic contribution
(particularly represented by NO 3
−, SO 4
2−, H +), the sea spray (Na +, Cl − and, to a lesser extent, K + and Mg 2+) and a terrigenous fraction, particularly characterized by higher Ca 2+ concentration; however, some concentration peaks of this ion have been found in association with some episodes of Saharan
dust transportation. 相似文献
19.
The new European Council Directive (PE-CONS 3696/07) frames the inhalable (PM 10) and fine particles (PM 2.5) on priority to chemically characterize these fractions in order to understand their possible relation with health effects.
Considering this, PM 2.5 was collected during four different seasons to evaluate the relative abundance of bulk elements (Cl, S, Si, Al, Br, Cu, Fe,
Ti, Ca, K, Pb, Zn, Ni, Mn, Cr and V) and water soluble ions (F −, Cl −, NO 2
−, NO 3
−, SO 4
2−, Na +, NH 4
+, Ca 2+ and Mg 2+) over Menen, a Belgian city near the French border. The air quality over Menen is influenced by industrialized regions on
both sides of the border. The most abundant ionic species were NO 3
−, SO 4
2− and NH 4
+, and they showed distinct seasonal variation. The elevated levels of NO 3
− during spring and summer were found to be related to the larger availability of the NO x precursor. The various elemental species analyzed were distinguished into crustal and anthropogenic source categories. The
dominating elements were S and Cl in the PM 2.5 particles. The anthropogenic fraction (e.g. Zn, Pb, and Cu) shows a more scattered abundance. Furthermore, the ions and elemental
data were also processed using principal component analysis and cluster analysis to identify their sources and chemistry.
These approach identifies anthropogenic (traffic and industrial) emissions as a major source for fine particles. The variations
in the natural/anthropogenic fractions of PM 2.5 were also found to be a function of meteorological conditions as well as of long-range transport of air masses from the industrialized
regions of the continent.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
20.
The concentrations of PM 10, PM 2.5 and their water-soluble ionic species were determined for the samples collected during January to December, 2007 at New Delhi
(28.63° N, 77.18° E), India. The annual mean PM 10 and PM 2.5 concentrations (± standard deviation) were about 219 (± 84) and 97 (±56) μgm −3 respectively, about twice the prescribed Indian National Ambient Air Quality Standards values. The monthly average ratio
of PM 2.5/PM 10 varied between 0.18 (June) and 0.86 (February) with an annual mean of ∼0.48 (±0.2), suggesting the dominance of coarser in
summer and fine size particles in winter. The difference between the concentrations of PM 10 and PM 2.5, is deemed as the contribution of the coarse fraction (PM 10−2.5). The analyzed coarse fractions mainly composed of secondary inorganic aerosols species (16.0 μgm −3, 13.07%), mineral matter (12.32 μgm −3, 10.06%) and salt particles (4.92 μgm −3, 4.02%). PM 2.5 are mainly made up of undetermined fractions (39.46 μgm −3, 40.9%), secondary inorganic aerosols (26.15 μgm −3, 27.1%), salt aerosols (22.48 μgm −3, 23.3%) and mineral matter (8.41 μgm −3, 8.7%). The black carbon aerosols concentrations measured at a nearby (∼300 m) location to aerosol sampling site, registered
an annual mean of ∼14 (±12) μgm −3, which is significantly large compared to those observed at other locations in India. The source identifications are made
for the ionic species in PM 10 and PM 2.5. The results are discussed by way of correlations and factor analyses. The significant correlations of Cl −, SO 42−, K +, Na +, Ca 2+, NO 3− and Mg 2+ with PM 2.5 on one hand and Mg 2+ with PM 10 on the other suggest the dominance of anthropogenic and soil origin aerosols in Delhi. 相似文献
|