Wet and dry deposition of formaldehyde in Izmir, Turkey

Samples were collected between May 2003 and May 2004 in Izmir, Turkey to measure dry and wet deposition of formaldehyde (HCHO). Particle-phase HCHO fluxes measured with dry deposition plates ranged between 2 and 56 microg m(-2) day(-1) (average+/-SD, 17+/-12 microg m(-2) day(-1)). Particulate phase dry deposition velocities calculated using the particulate fluxes measured and ambient particulate concentrations ranged from 0.1 to 9.6 cm s(-1) (1.4+/-1.4 cm s(-1)). The particulate overall dry deposition velocity agreed well with those measured previously for other pollutants using the same method. Formaldehyde concentration measured in 27 rain samples collected at the sampling site ranged between 10 and 304 microg l(-1). The annual formaldehyde wet deposition was calculated as 31.4 mg m(-2) year(-1). The annual HCHO total deposition (wet+dry) was dominated by wet deposition (83.7%).     

The determination of gas phase dry deposition fluxes and mass transfer coefficients (MTCs) of polychlorinated biphenyls (PCBs) using a modified water surface sampler (WSS)

Gas phase PCB dry deposition and concentration samples were collected simultaneously between July 2004 and May 2005 at a suburban site in Bursa, Turkey. A modified water surface sampler (WSS) was employed to collect gas phase fluxes while a high-volume air sampler (HVAS) was used for concentration samples. The WSS was able to collect both particle and gas phase PCB deposition samples. The collected PCBs on water surface were captured by a filter and an XAD-2 resin column during water cycle. The average of gas phase PCB deposition flux, determined by analyzing the XAD-2 resin column, was 79.3+/-40.5 ng m(-2) d(-1) and its percentage in total (gas+particle) PCB flux was about 60. The average of gas phase PCB concentration measured concurrently with flux samples was 224.4+/-160.2 pg m(-3) and its ratio to the total (gas+particle) PCB concentration was 85%. This difference was likely due to the different deposition characteristics of gases and particulates. Dominant PCB homolog groups were 3-4 chlorobiphenyls (CBs) for both ambient air and gas phase deposition samples. Mass transfer coefficients (MTC, K(g)) for air-side were determined using gas phase flux and ambient air concentration values. The average overall K(g) ranged between 0.21 and 0.96 cm s(-1) with an average of 0.60+/-0.19 cm s(-1).     

An evaluation of direct measurement techniques for mercury dry deposition

In this project, several surrogate surfaces designed to directly measure Hg dry deposition were investigated. Static water surrogate surfaces (SWSS) containing deionized (DI), acidified water, or salt solutions, and a knife-edge surrogate surface (KSS) using quartz fiber filters (QFF), KCl-coated QFF and gold-coated QFF were evaluated as a means to directly measure mercury (Hg) dry deposition. The SWSS was hypothesized to collect deposited elemental mercury (Hg⁰), reactive gaseous/oxidized mercury (RGM), and mercury associated with particulate matter (Hg_(p)) while the QFF, KCl-coated QFF, and gold-coated QFF on the KSS were hypothesized to collect Hg_(p), RGM + Hg_(p), and Hg⁰ + RGM + Hg_(p), respectively. The Hg flux measured by the DI water was significantly smaller than that captured by the acidified water, probably because Hg⁰ was oxidized to Hg²⁺ which stabilized the deposited Hg and decreased mass transfer resistance. Acidified BrCl, which efficiently oxidizes Hg⁰, captured significantly more Hg than other solutions. However, of all collection media, gold-coated QFFs captured 6 to 100 times greater Hg mass than the other surfaces, probably because there is no surface resistance for Hg⁰ deposition to gold surfaces. In addition, the Hg⁰ concentration is usually 100-1000 times higher than RGM and Hg_(p). For all other media, co-located samples were not significantly different, and the combination of daytime plus nighttime results were comparable to 24-h samples, implying that Hg⁰, RGM and Hg_(p) were not released after they deposited nor did the surfaces reach equilibrium with the atmosphere. Based on measured Hg ambient air concentrations and fluxes, dry deposition velocities of RGM and Hg⁰ to DI water and other surfaces were 5.6 ± 5.4 and 0.005-0.68 cm s⁻¹ in this study, respectively. These results suggest surrogate surfaces can be used to measure Hg dry deposition; however, extrapolating the results to natural surface can be challenging.     

Atmospheric deposition of carbon and nutrients across an arid metropolitan area

Urbanization is increasing rapidly in semi-arid environments and is predicted to alter atmospheric deposition of nutrients and pollutants to cities as well as to ecosystems downwind. We examined patterns of wet and coarse dry deposition chemistry over a five-year period at 7 sites across the Central Arizona-Phoenix (CAP) study area, one of two urban sites within the National Science Foundation's Long-Term Ecological Research (LTER) program. Wet and dry deposition of organic carbon (oC) were significantly elevated in the urban core; in contrast, mean annual wet and dry fluxes of nitrogen (N) were low (<6 kg ha(-1) yr(-1)) compared to previous estimates and did not differ significantly among sites. Wet deposition of sulfate (SO(4)2-) was high across CAP (mean 1.39 kg ha(-1) yr(-1) as S) and represented the dominant anion in rainfall. Dry deposition rates did not show strong seasonal trends with the exception of oC, which was 3-fold higher in winter than in summer; ammonium (NH4+) deposition was high but more variable. Dry deposition of NO3- and oC was strongly correlated with particulate base cations and dust-derived soluble reactive phosphorus (SRP), suggesting that urban-derived dust is scrubbing the atmosphere of acidic gases and entrained particles and increasing local deposition. Differences between measured and predicted rates of dry N deposition to the urban core may be explained by incomplete collection of gas phase N on surrogate deposition surfaces in this hot and arid environment. The extent of urban enhancement of cations and oC inputs to desert ecosystems appears to be restricted to the urbanized metropolitan area rather than extending far downwind, although a low number of sites make it difficult to resolve this spatial pattern. Nevertheless, wet and dry inputs may be important for biogeochemical cycles in nutrient and carbon-poor desert ecosystems within and near arid cities.     

A modified technique for field measurements of dry deposition fluxes of polychlorinated biphenyls in tropical regions

This report focused on the development of a technique to measure dry deposition fluxes of PCBs in tropical environments. Temperature resistant double-adhesive tape has been used as a new surrogate surface for collection of deposited PCBs. The new technique includes the measurement of field blanks for the entire sampling period. A sonication-assisted extraction procedure has been validated for the extraction of PCBs from the tape. The new technique has been used in the field for a period of 4 months in the tropical region of Singapore. The average dry deposition flux measured for total PCBs was 15.3 ng m(-2) day(-1) and, on a global scale, this can be considered to be low.     

Atmospheric deposition of nitrogen at five subtropical forested sites in South China

Elevated concentrations of reactive nitrogen (N) in precipitation have been reported for many cities in China. Due to increased use of fossil fuels and expansion in agriculture, further increases in deposition of ammonia (NHx) and reactive N oxides (NOy) are predicted. Increased deposition of reactive N is likely to affect N dynamics and N runoff in forest ecosystems. Yet, in China little work has been done to quantify the levels of atmospheric N deposition in such systems. Here, we assess the deposition of inorganic N (ammonium, NH4+ and nitrate, NO3-) for five subtropical forest ecosystems in remote and urban areas of South China. Annual volume-weighted concentrations in bulk precipitation range from 0.18 to 1.55 mg NH4+ -N L(-1) and from 0.12 to 0.74 mg NO3- -N L(-1). These values are large and several times greater than those reported for remote sites of the world. The fluxes of total inorganic N (TIN) in wet-only deposition range from 0.8 to 2.3 g N m(-2) yr(-1), with NH4+ -N contributing 54% to 77%. Both the tree canopy and the ground vegetation layer are important in determining the net N flux reaching the forest floor, but the net effect varies from site to site. At TieShanPing (TSP), close to Chongqing city, and at CaiJiaTang (CJT), near Shaoshan (Hunan province), the canopy represents a net source of N, probably due to dry deposition. At the other three sites (LiuChongGuan (LCG), LeiGongShan (LGS), both in Guizhou province, and LiuXiHe (LXH) in Guangdong), a net loss of reactive N from precipitation water occurs in the canopy, probably due to uptake processes. The total annual atmospheric TIN load is estimated to range from at least 0.8 g N m(-2) yr(-1) to 4.0 g N m(-2) yr(-1), with a considerable contribution from dry deposition. Concentrations and fluxes of inorganic N in tree canopy throughfall are greater than those in North America. Also the contribution of NH4+ -N to TIN fluxes in throughfall (40% to 70%) is greater than in North America. Our sites have N deposition levels and NH4+ -N contributions similar to those found in Northwest and central Europe. The TIN loads at TSP and CJT far exceed 2.5 g N m(-2) yr(-1), which is the N deposition load above which NO3- leaching is expected in temperate and boreal forests.     

Intercomparison study of atmospheric mercury models: 2. Modelling results vs. long-term observations and comparison of country deposition budgets

Five regional scale models with a horizontal domain covering the European continent and its surrounding seas, two hemispheric and one global scale model participated in the atmospheric Hg modelling intercomparison study. The models were compared between each other and with available measurements from 11 monitoring stations of the EMEP measurement network. Because only a very limited number of long-term measurement records of Hg were available, significant attention was given to the intercomparison of modelling results. Monthly and annually averaged values of Hg concentrations and depositions as well as items of the Hg deposition budgets for individual European countries were compared. The models demonstrated good agreement (within +/-20%) between annual modelled and observed values of gaseous elemental Hg. Modelled values of Hg wet deposition in Western and Central Europe agreed with the observations within +/-45%. The probability to predict wet depositions within a factor of 2 with regard to measurements was 50-70% for all the models. The scattering of modelling results for dry depositions of Hg was more significant (up to +/-50% at the annual scale and even higher for monthly data). Contribution of dry deposition to the total Hg deposition was estimated at 20-30% with elevated dry deposition fluxes during summer time. The participating models agree in their predictions of transboundary pollution for individual countries within +/-60% at the monthly scale and within +/-30% at the annual scale. For the cases investigated, all the models predict that the major part of national anthropogenic Hg emissions is transported outside the country territory.     

Inhalation exposure of traffic police officers to polycyclic aromatic hydrocarbons (PAHs) during the winter in Beijing, China

This study concerns the use of personal samplers to evaluate the exposure of traffic police to polycyclic aromatic hydrocarbons (PAHs) during the winter of 2005 in Beijing. We measured the samples collected for gas and particulate phases PAHs with the same technique used for an earlier study during the summer of 2004, and evaluated exposure risk based on the calculated benzo(a)pyrene equivalent concentrations (BaP(eq)) of both summer and winter. The mean exposure concentrations of gaseous and particulate phase PAHs in the winter are 4300+/-2900 ng/m(3) and 750+/-1000 ng/m(3), respectively, significantly higher than those measured simultaneously at control sites and also considerably higher than the values measured during the summer. The exposure PAH profiles for police and the control subjects are similar with predominant naphthalene in gaseous phase and dominant fluoranthene, pyrene, anthracene and naphthalene in particulate phase. Large daily variations occur both in summer and winter, because of the changes in the weather conditions especially wind speed and relative humidity which tend to disperse and scavenge PAHs in air. In the winter, the average BaP(eq) value for traffic police is 82.1 ng/m(3), which is significantly higher than those for the control subjects and the national standard of 10 ng/m(3) for ambient air. Particulate phase PAHs contribute more than 90% of the total exposure risk in the winter. Annually, weighted-average probabilities of exceeding the national standard (10 ng/m(3)) are 69.3% and 20.6% for the police and the controls, respectively.     

Cadmium transport in the Lot-Garonne River system (France) - temporal variability and a model for flux estimation

Fluvial cadmium (Cd) inputs into the Gironde estuary via the Lot-Garonne River system were evaluated using nine years of daily measurements of water discharge and total suspended sediment content (TSS) combined with monthly analyses of dissolved and particulate Cd concentrations. This study demonstrates that dissolved and particulate Cd concentrations in the Lot River have strongly decreased in the early 1990s. However, dissolved and particulate Cd concentrations in the Lot River are still higher than those in the Garonne River. In 1992-1998 mean annual Cd concentrations are more or less constant and thus, annual Cd fluxes mainly depend on hydrology. Daily total Cd fluxes range from 0.26 to 966 kg day(-1) in the Lot River and from 0.31 to 1360 kg day(-1) in the Garonne River, downstream their confluence. During dry years, Cd fluxes at La Réole are dominated by inputs from the upstream Garonne River, whereas during wet years they are controlled by inputs from the polluted Lot River watershed. The relation between particulate and dissolved Cd fluxes depends on TSS concentrations, which appear to be mainly controlled by the succession of floods and low waters reflecting short-term basin-scale climate variability. Cadmium concentrations, fluxes and the ratio between the particulate and dissolved Cd fluxes depends on the absolute value and instantaneous evolution (strong relative increase or decrease) of discharge. An empiric model permits deducing intervals of daily dissolved Cd fluxes from discharge, hydrological key situation and related intervals of 'typical' dissolved Cd concentrations. In 1992-1998 the Lot-Garonne River system shows close relations between annual dissolved and particulate Cd fluxes. These relations allow deducing annual particulate Cd fluxes using annual dissolved Cd fluxes obtained from the model. The validation a posteriori shows that our empiric model accurately reproduces the annual Cd fluxes estimated from the field data with uncertainty lower than 25% for dissolved fluxes and lower than 30% for the particulate fluxes. Consequently, the empiric model permits estimating annual dissolved and particulate Cd fluxes in the Lot-Garonne River system, from daily discharge data, without Cd analysis. Cadmium fluxes obtained from the model may be used as approximate values for gross fluvial Cd inputs into the Gironde estuary.     

Mercury in the air, water and biota at the Great Salt Lake (Utah, USA)

The Great Salt Lake, Utah (USA), is the fourth largest terminal lake on Earth and a stop-over location for 35 million birds on the Pacific Flyway. Recently, the Utah Department of Health and Utah Division of Wildlife Resources issued tissue mercury (Hg) consumption advisories for several species of birds that consume the lake's brine shrimp. We hypothesized that the chemistry of the atmosphere above the Great Salt Lake would facilitate atmospheric deposition of Hg to the water. Because little information was available on Hg at the Great Salt Lake, and to begin to test this hypothesis, we measured atmospheric elemental (Hg(0)) and reactive gaseous mercury (RGM) concentrations as well as Hg concentrations in water and brine shrimp five times over a ~year. Surrogate surfaces and a dry deposition model were applied to estimate the amount of Hg that could be input to the lake surface, and HYSPLIT model back trajectories were developed to investigate potential sources of RGM to the lake. Atmospheric Hg(0) concentrations were similar to global ambient background values and RGM concentrations were similar to those reported for rural areas. Both Hg(0) and RGM exhibited regular diel variability. Model estimated deposition velocities for RGM to the lake ranged from 0.9 to 3.0 cm s(-1) while that determined for surrogate surfaces ranged from 2.8 to 7.8 cm s(-1). Filtered total and methyl Hg concentrations in Great Salt Lake surface waters were consistent throughout the year (3.6+/-0.8 ng L(-1) and 0.93+/-0.59 ng L(-1), respectively), while brine shrimp concentrations had a statistically significant increase from summer to fall. Data collected and data analyses indicated no direct local or regional source of Hg to the lake and that factors within the Great Salt Lake basin are important in controlling Hg(0) and RGM concentrations.     

Cloud water deposition at a high-elevation site in the Vosges Mountains (France)

The importance of cloud water deposition fluxes to a high-elevation site in the Vosges Mountains (France) has been studied. An existing one-dimensional cloud water deposition model has been adapted to site conditions. The adaptation of the main parameters has been tested and is discussed. These tests illustrate the small influence of the surface area index (SAI) and the roughness length on cloud water deposition and the negligible contribution of sedimentation compared to impaction of cloud droplets. Model input data, including cloud water composition, liquid water content (LWC) and wind speed, have been collected over a 1-year period and are used to evaluate annual cloud deposition fluxes of major ions and trace metals. The calculations indicate that the hydrologic input by cloud water (55.5 mm year(-1)) is negligible compared to the input by rainwater (1265 mm year(-1)). However, due to the higher concentrations in cloud water, the deposition fluxes of cloud water represent 10-28% of the total wet deposition (rain + cloud deposition) for major ions and 50% or higher for trace elements.     

Evolution of anthropogenic aerosols in the coastal town of Salina Cruz, Mexico: part II particulate phase chemistry

An analysis of atmospheric gases and particles during periods of land and sea breezes in a coastal city in southwest Mexico indicates limited removal of total particle mass by deposition during periods when the air resides over the ocean. The average PM(2.5) mass concentrations for land and sea breeze samples were 25+/-1.0 and 26+/-1.0 microg m(-3), respectively. The average sum of the ion concentrations (NH(4)(+), SO(4)(2-), NO(3)(-), Na(+), Cl(-)) were 10 and 11.8 microg m(-3) for the samples taken during land and sea breeze periods. The average total carbon concentrations were 6.0 and 5.3 microg m(-3) for land and sea breeze periods. The mass of sulfate in particles of ocean origin, 3.3+/-2.8 microg m(-3), is marginally higher than those originating from the land, 2.0+/-0.8 microg m(-3), presumably as a result of the conversion of SO(2) recirculated from the city. The fraction of sulfate, nitrate and ammonium ions in rainwater samples is almost a factor of two higher than the fraction measured on filtered air samples. The rainwater also contains significant concentrations of elemental and organic carbon. This study, although extending over a period of only 15 days, with limited chemical samples, suggests that recirculation of anthropogenic particles from coastal cities should be taken into consideration when diagnosing and predicting air quality in such regions.     

Foliar exchange of mercury as a function of soil and air mercury concentrations

Previous research has indicated that foliar mercury (Hg) flux is bi-directional, with influence from both atmospheric and soil Hg. This work investigated the role of soil and air Hg concentrations on foliar Hg exchange using a single-plant gas-exchange system. The exchange of Hg vapor with aspen seedlings grown in soil Hg concentrations of 0.03+/-0.01, 5.8+/-0.5, and 12.3+/-1.3 microg g(-1) and exposed to atmospheric Hg concentrations of 2.4+/-0.5, 11.0+/-0.9, and 30.4+/-2.2 ng m(-3) was measured. At background atmospheric Hg concentrations of 2.4 ng m(-3), foliage released Hg at all three soil Hg concentrations and fluxes ranged from 1.6 to 5.5 ng/m(2)/h. At higher atmospheric Hg concentrations (>11 ng m(-3)), net deposition to foliage ranged from -9 to -47 ng/m(2)/h, exhibiting increase uptake with higher air Hg concentrations. Fluxes associated with aspen showed an immediate response to changes in atmospheric Hg concentrations. Compensation points, the air concentration where no net flux of Hg vapor occurred, were 3-4 ng m(-3) in the light and 2-3 ng m(-3) in the dark for trees grown in soils of 0.03 and 6 microg g(-1) Hg content, and 5-6 ng m(-3) in the light and 2.5-3.5 ng m(-3) in the dark for trees grown in 12 microg g(-1) Hg soils.     

Effects of nitrogen deposition on nitrogen cycling in an Aleppo pine stand in Athens, Greece

High levels of nitrogen deposition measured in throughfall fluxes in 2002, reaching 38 kg ha(-1) year(-1), affected the biogeochemical cycle of N in an Aleppo pine (Pinus halepensis) stand situated in Athens, the capital of Greece. The N fluxes in bulk deposition were far lower than those in throughfall indicating high levels of dry deposition in the city of Athens. The amounts of N in litterfall and those stored in the forest floor and mineral soil were not high, while the mean residence time of N in the forest floor, derived from fluxes equations, decreased considerably due to the high levels of N fluxes in throughfall deposition. Nitrogen concentration in needle tissues was high and this resulted in a high ratio of N/Zn. Zinc availability was low due to the alkaline nature of soil in the study area. Fast N cycling may affect the living status of Aleppo pine, which is an oligotrophic plant species capable of occupying poor soil sites. Nitrogen eutrophication may adversely affect forests grown on calcareous soils by developing nutrition imbalances between N and micronutrients, the solubility of which depends on soil pH values.     

Elemental carbon and respirable particulate matter in the indoor air of apartments and nursery schools and ambient air in Berlin (Germany)

This study was performed to examine exposure to typical carcinogenic traffic air pollutants in the city center of an urban area. In all, 123 apartments and 74 nursery schools were analyzed with and without tobacco smoke interference and the households in two measuring periods. Simultaneously, the air outside 61 apartment windows as well as the average daily traffic volume were measured. Elemental carbon (EC), the marker for particulate diesel exhaust and respirable particulate matter (RPM) were determined. The thermographic EC analysis was conducted with and without prior solvent extraction of the soluble carbon fraction. Comparison of these two thermographic EC measurements clearly showed that method-related differences in the results, especially for indoor measurements, when high background loads of organic material were present (e.g. tobacco smoke), existed. Solvent extraction prior to EC determination was therefore appropriate. For the first winter measuring period, the EC concentration levels without solvent extraction in the indoor air were about 50% higher than those measured in the spring/summer period. In the second measuring period (i.e. spring/summer), the median EC concentrations after solvent extraction were 1.9 microg/m3 for smokers' apartments and 2.1 microg/m3 for non-smokers' apartments, with RPM concentrations of 57 and 27 microg/m3, respectively. Nursery schools showed high concentrations with median values of 53 microg/m3 for RPM and 2.9 microg/m3 for EC after solvent extraction. A significant correlation between the fine dust and EC concentrations (after solvent extraction) in the indoor and ambient air was determined. Outdoor EC values were also correlated with the average daily traffic volume. The EC ratios between indoor and ambient concentration showed a median of 0.8 (range: 0.3-4.2) in non-smoker households and 0.9 (range: 0.4-1.5) in smoker apartments. Furthermore, the EC/RPM ratio in indoor and ambient air was 0.01-0.15 (median 0.06) and 0.04-0.37 (median 0.09), respectively. PRACTICAL IMPLICATIONS: In the absence of indoor sources a significant correlation with regard to respirable particulate matter (RPM) and elemental carbon concentrations between the indoor and ambient air of apartments was observed. The high degree of certainty resulting from this correlation underscores the importance of ambient air concentrations for indoor air quality. In nursery schools we found higher concentrations of RPM. An explanation of these results could be the high number of occupants in the room, their activity and the cleaning intensity.     

Factors affecting stomatal uptake of ozone by different canopies and a comparison between dose and exposure

Measured ozone (O(3)) and carbon dioxide (CO(2)) concentrations and fluxes over five different canopies (mixed coniferous-deciduous forest, deciduous forest, corn, soybean and pasture) in the eastern USA were analyzed to investigate the stomatal uptake of O(3). It was found that the ambient O(3) concentration levels had little effect on stomatal conductance. However, the accumulated stomatal uptake of O(3), upon reaching a threshold value on any given day, appears to reduce the rate of further O(3) uptake substantially. This may explain why the maximum O(3) deposition velocity often appeared in the early morning hours over some forest canopies. Substantially reduced CO(2) fluxes over wet canopies compared to dry canopies suggest that stomata were likely partially or totally blocked by water droplets or films when canopies were wet. By using a big-leaf dry deposition model, measured O(3) fluxes were separated into stomatal and non-stomatal portions. It was estimated that stomatal uptake contributed 55-75% of the total daytime O(3) fluxes and 40-60% of the total daytime plus nighttime fluxes, depending on canopy type. This suggests that about half of the total O(3) flux occurred through the non-stomatal pathway. At three locations (deciduous forest, corn and soybean sites), O(3) concentrations of 30-60 ppb and of 60-85 ppb contributed equally to the accumulated stomatal fluxes, while at the other two locations (mixed coniferous-deciduous forest and pasture sites), concentrations of 30-60 ppb contributed twice as much as those from 60 to 85 ppb.     

Particle size distribution and atmospheric metals measurements in a rural area in the South Eastern USA

Atmospheric particle mass concentrations were measured at a site adjacent to Lake Hartwell, GA, during six dry sampling events in February-March 2003. The overall average PM2.5 mass concentration was 9.5 microg/m3 and the overall average total suspended particles mass concentration was 19.1 microg/m3. Particulate matter was collected on a deposition plate mounted onto a specially designed wind vane and was subsequently analyzed to determine the particle size distribution. The average geometric particle diameter was found to be 2.8 microm. Particulate matter collected was found to be closely approximately at log-normal distribution, with a count median diameter of 1.5 mum and a geometric standard deviation of 1.8. Individual metal concentrations present in airborne particulate matter were determined for cadmium, chromium, copper, iron, lead, manganese, nickel, and zinc using inductively coupled plasma-mass spectrometry analysis of samples collected on Teflon filters. Ambient metal concentrations were found to range from 0.8 ng/m3 for cadmium to 512 ng/m3 for iron. The dry deposition flux of metals was estimated to be in the range of 0.17 mg/(m2 year) for cadmium to 102 mg/(m2 year) for iron. More samples need to be collected and analyzed, both temporally and spatially, in order to establish atmospheric metals fluxes onto surfaces.     

Copper dispersal in a water-supply reservoir

Granular (“diamond”) copper sulfate was applied for algal control to the surface of Hoover Reservoir, Franklin Co., Ohio. Soluble and particulate Cu²⁺ concentrations were measured by atomic absorption spectrophotometry at several depths for up to 96 hr after application. The soluble Cu²⁺ concentration decreased to near baseline values in 2 or 6 hr when 0.2 or 0.4 g Cu²⁺/m² was applied was applied respectively. Most of the copper sulfate dissolved in the first 1.75 m of the water column and only 2% of the total copper sulfate reached a depth of at least 4.5 m. A concentration of 0.4 g Cu²⁺/m² controlled a diatom bloom consisting primarily of Melosira spp., Stephanodiscus astraea var. minutula and Asterionella formosa. The largest decrease in dry weight and algal cell numbers was observed 24 hr after copper sulfate treatment.     

Sources, distribution and variability of hydrocarbons and metals in atmospheric deposition in an urban area (Paris, France)

Total atmospheric deposition, i.e., both wet and dry deposition, was sampled during 11 months in the "Ile-de-France" region, France. Monthly fluxes of aliphatic hydrocarbons (AHs), polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) were studied at three representative sites (two urbanised and one semiurban). A combination of spatial and temporal variability of total fluxes and pollutant fingerprints allows a better understanding of atmospheric pollutant dynamics over this region. In the whole studied area, aggregated total atmospheric fluxes of AHs, PAHs and HMs range from 19 to 33 mg m(-2) y(-1), 99 to 161 mug m(-2) y(-1) and 48 to 103 mg m(-2) y(-1), respectively. The highest values are observed in Paris centre, reflecting the importance of the urban centre as a source of pollutants, with a decline in many atmospheric deposits when moving away from urban areas. The seasonal distribution of these pollutants suggests the impact of residential heating on urban atmospheric deposition of hydrocarbons and the increase of dust loads containing HMs during summer. The qualitative study performed on atmospheric deposition data highlights the main sources of pollutants. Aliphatic fingerprints suggest a marked contribution of biogenic inputs to aliphatic contamination in the whole Ile-de-France region and slight petroleum inputs in urban areas. Aromatic fingerprints, characterised by the great predominance of phenanthrene, fluoranthene and pyrene, associated with some specific ratio values, suggest the mixture of petrogenic and pyrolytic contaminations of atmospheric deposition in the whole "Ile-de-France" region. HM distribution shows the presence of anthropogenic sources of Al and Fe in this area and the stationary sources (incinerators and plants) as a significant source of Si, S and Sb in the urban atmosphere. Moreover, a pollutant mix phenomenon, occurring in such an urban atmosphere, shows a significant influence on atmospheric deposition at the semiurban site.