Atmospheric concentrations of nitric acid, sulfur dioxide, particulate nitrate and particulate sulfate, and estimation of their dry deposition on the urban- and mountain-facing sides of Mt. Gokurakuji, Western Japan

Atmospheric concentrations of nitric acid (HNO₃), sulfur dioxide (SO₂), particulate nitrate and particulate sulfate on the urban- and mountain-facing sides of Mt. Gokurakuji were measured from November 2002 to October 2003, in order to evaluate the effects of anthropogenic activity on air quality and dry deposited nitrate and sulfate on the surfaces of pine foliage. The results showed that HNO₃, SO₂ and concentrations were significantly higher (P < 0.05) on the urban-facing side (1.54, 2.48 and 0.65 μg m⁻³, respectively) than the mountain-facing side (0.67, 1.19 and 0.37 μg m⁻³, respectively), while concentrations did not differ significantly between the two sides (urban-facing: 2.80 μg m⁻³; mountain−facing: 2.05 μg m⁻³). Indirect estimates of dry deposition rates of nitrate and sulfate to the surfaces of pine foliage based on the measured concentrations approximately agreed with the measured values determined by the foliar rinsing technique in a previous study. It was found that HNO₃ was the major source (approximately 80%) of dry deposited nitrate on pine foliage, while the contribution from was about equal to that from SO₂. In conclusion, HNO₃ and SO₂ appear to be dominant species reflecting higher dry deposition rates of nitrate and sulfate on the urban-facing side compared to the mountain-facing side of Mt. Gokurakuji.     

Atmospheric deposition of major and trace elements in Amman, Jordan

Wet and dry deposition samples were collected in the capital of Jordan, Amman. Concentrations of Al, Ba, Bi, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sb, V, Zn, Fe, Sr, Mg²⁺, Ca²⁺, Na⁺, K⁺, Cl⁻, NO₃ ⁻ and SO₄ ²⁻, along with pH were determined in collected samples. Mean trace metal concentrations were similar or less than those reported for other urban regions worldwide, while concentrations of Ca²⁺ and SO₄ ²⁻ were among the highest. High Ca²⁺ concentrations were attributed to the calcareous nature of the local soil and to the influence of the Saharan dust. However, high SO₄ ²⁻ concentrations were attributed to the influence of both anthropogenic and natural sources. Except for Cl⁻, NO₃ ⁻, SO₄ ²⁻ and Cu, monthly dry deposition fluxes of all measured species were higher than wet deposition fluxes. The annual wet deposition fluxes of trace metals were much lower than those reported for other urban areas worldwide.     

Sulphate, Nitrogen and Base Cation Budgets at 21 Forested Catchments in Canada, the United States and Europe

To assess the concern over declining base cation levels in forest soils caused by acid deposition, input-output budgets (1990s average) for sulphate (SO₄), inorganic nitrogen (NO₃-N; NH₄-N), calcium (Ca), magnesium (Mg) and potassium (K) were synthesised for 21 forested catchments from 17 regions in Canada, the United States and Europe. Trend analysis was conducted on monthly ion concentrations in deposition and runoff when more than 9 years of data were available (14 regions, 17 sites). Annual average SO₄ deposition during the 1990s ranged between 7.3 and 28.4 kg ha⁻¹ per year, and inorganic nitrogen (N) deposition was between 2.8 and 13.8 kg ha⁻¹ per year, of which 41–67% was nitrate (NO₃-N). Over the period of record, SO₄ concentration in deposition decreased in 13/14 (13 out of 14 total) regions and SO₄ in runoff decreased at 14/17 catchments. In contrast, NO₃-N concentrations in deposition decreased in only 1/14 regions, while NH₄-N concentration patterns varied; increasing at 3/14 regions and decreasing at 2/14 regions. Nitrate concentrations in runoff decreased at 4/17 catchments and increased at only 1 site, whereas runoff levels of NH₄-N increased at 5/17 catchments. Decreasing trends in deposition were also recorded for Ca, Mg, and K at many of the catchments and on an equivalent basis, accounted for up to 131% (median 22%) of the decrease in acid anion deposition. Base cation concentrations in streams generally declined over time, with significant decreases in Ca, Mg and K occurring at 8, 9 and 7 of 17 sites respectively, which accounted for up to 133% (median 48%) of the decrease in acid anion concentration. Sulphate export exceeded input at 18/21 catchments, likely due to dry deposition and/or internal sources. The majority of N in deposition (31–100%; median 94%) was retained in the catchments, although there was a tendency for greater NO₃-N leaching at sites receiving higher (<7 kg ha^-1 per year) bulk inorganic N deposition. Mass balance calculations show that export of Ca and Mg in runoff exceeds input at all 21 catchments, but K export only exceeds input at 16/21 sites. Estimates of base cation weathering were available for 18 sites. When included in the mass balance calculation, Ca, Mg and K exports exceeded inputs at 14, 10 and 2 sites respectively. Annual Ca and Mg losses represent appreciable proportions of the current exchangeable soil Ca and Mg pools, although losses at some of the sites likely occur from weathering reactions beneath the rooting zone and there is considerable uncertainty associated with mineral weathering estimates. Critical loads for sulphur (S) and N, using a critical base cation to aluminium ratio of 10 in soil solution, are currently exceeded at 7 of the 18 sites with base cation weathering estimates. Despite reductions in SO₄ and H⁺ deposition, mass balance estimates indicate that acid deposition continues to acidify soils in many regions with losses of Ca and Mg of primary concern. The U.S. Government's right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged. The Canadian Crown reserves the right to retain a non-exclusive, royalty free licence in and to any copyright.     

Interactions of Atmospheric Deposition with Coniferous Canopies in Estonia

Throughfall and open field bulk precipitation were measured at three coniferous sites during 1995–2002 in the framework of ICP Integrated Monitoring and at five coniferous sites during 1996–2002 in the framework of ICP Forests (Level II). The coniferous canopies acted as a sink for nitrate and ammonium and as a source for base cations: Ca²⁺, Mg²⁺ and K⁺. The estimated share of SO₄–S dry deposition from total deposition was 1.5–4 times higher for dormant period compared to growing period. During the study period average annual throughfall and bulk deposition of SO₄–S decreased significantly, 2.8 and 2.3 times, respectively. Throughfall enrichment with base cations increased in the order Mg < Na < Ca < K. Using Na as a tracer ion, average dry deposition and canopy leaching were calculated. Leaching was the dominant process for TF enrichment by potassium. Leaching of base cations occurred during growing as well as dormant period. The calculated internal flux of Ca²⁺ and Mg²⁺ varied in the range of 0.6–2.0 and 0.6–1.2 kg ha⁻¹ per year in spruce and pine stands, respectively. The internal circulation of K⁺ was significantly higher (8.9–10.9 kg ha⁻¹ per year) in spruce stands than in pine stands (2.7–4.4 kg ha⁻¹ per year).     

Toxicity of a complex mixture of atmospherically transported pesticides to Ceriodaphnia dubia

The presence of several anthropogenic chemicals has been documented in the atmosphere of the Canadian prairies. The deposition of these chemicals as a mixture is of importancesince little is known of the combined effects of these chemicalson aquatic organisms. This study was designed to evaluate theacute and chronic toxicity of a complex mixture of nineatmospherically transported pesticides to Ceriodaphniadubia. The nine selected pesticides (bromoxynil, dicamba, 2,4-D,MCPA, triallate, trifluralin, pentachlorophenol, lindane, and4,4-DDT) were detected in appreciable quantities in dryatmospheric deposits. The concentration of each pesticide in themixture was based on maximum measured daily dry deposition ratesfor central Canada, except for pentachlorophenol, which wasestimated based on atmospheric concentrations. The 48-h LC50estimate for C. dubia exposed to the pesticide mixture was174.60 g L^-1 (340 times the measured total dry deposition concentration). The estimated NOEC and LOEC for bothsurvival and reproduction, as determined in the 7-d chronic toxicity test, were 51.3 (100 times) and 154 g L^-1 (300 times), respectively. A basic risk assessment, using the toxic unit approach, suggested that the toxicity of the pesticide mixture was mainly due to 4,4-DDT. Overall, this atmospherically transported complex mixture of pesticides appearsto pose a negligible toxicological risk to non-target aquatic invertebrates such as zooplankton.     

Wet atmospheric deposition of nitrogen: 20 years measurement in Shenzhen City, China

We presented measurements of wet deposition of NH ₄ ⁺ –N and NO ₃ ^? –N from 1986 to 2006 in Shenzhen City, China. Over the past 20 years, NO ₃ ^? –N concentration had significantly increased, but a reverse trend was found for NH ₄ ⁺ –N. The main form of total inorganic nitrogen (TIN) was NH ₄ ⁺ –N and the average NH ₄ ⁺ –N/NO ₃ ^? –N ratio was 1.57 in this area. The contribution of NO ₃ ^? –N to TIN increased from 28–42% in the period of 1986–2000 to 50–63% during 2001–2006. The increased deposition flux of NO ₃ ^? –N resulted in the increasing trend of TIN, although NH ₄ ⁺ –N showed a decreasing trend over time. Average deposition flux of TIN during 1986–2006 was 13.24 kg/ha/year, with a minimum value of 6.03kg/ha/year in 1988 and a maximum value of 20.52 kg/ha/year in 1997. Wet deposition fluxes of N appeared to vary with season, 81% occurred in the warm season (from April to September). The wet deposition of TIN to the Shenzhen Reservoir reached 8,902 kg in 2006, which contributed 9.95% of the total nonpoint pollution to the reservoir and will be increased in the future.     

A Gradient Study of 34 Elements in the Vicinity of a Copper-Nickel Smelter in the Kola Peninsula

Concentrations of 34 elements determined by ICP mass spectrometry were studied in surface soil and vegetation along a north–south gradient through the Pechenganickel smelter complex in Kola peninsula, northern Russia. Strong influence from the smelter was evident for Fe, Co, Ni, and Cu, mainly associated with dry deposition of large particles. Also for As, Se, Mo, Sb, Te, Bi, and Pb the smelter or associated sources appeared to be distinct contributors of contamination consisting presumably of smaller particles. Significant but less distinct effects leading to enhanced concentration levels were observed for P, S, V, Cr, Zn, and Tl. In the case of Mn, Rb, Sr, Cs, and Ba the concentrations in vegetation were generally lower near the source, which may be due to cation exchange with protons or heavy metal cations in the soil and subsequent leaching from the root zone. For Li, Be, B, Na, Mg, Al, Ca, Y, Cd, La, Th, and U no particular influence from the smelter complex was observed. Some characteristic differences observed in element concentrations in different plant species and between different years of Pinus sylvestris needles are discussed. The high concentrations observed for many trace elements in the humus horizon indicates that it acts as an active biogeochemical barrier against downward transport of these elements.     

Sulfate exports from multiple catchments in a glaciated forested watershed in western New York, USA

Sulfate () concentrations and fluxes were studied for multiple storm events in the Point Peter Brook watershed, a glaciated, forested watershed located in Western New York, USA. Investigations were performed across one large (696 ha) and three small (1.6–3.4 ha) catchments with varying extent of riparian and wetland areas. Concentrations of in groundwater sources (mean values: 238–910 μmol_c L⁻¹) were considerably greater than concentrations recorded for rainfall (60 μmol_c L⁻¹) and throughfall (72–129 μmol_c L⁻¹). Seasonality in concentrations was most pronounced for valley-bottom riparian waters with maximum concentrations in late winter–spring (February–March) and a minimum in late summer (August). Concentrations of in wetland water were considerably less than riparian water indicating the likelihood of reduction in anoxic wetland conditions. Storm events displayed a dilution pattern in concentrations with a minimum coinciding with the maximum in throughfall contributions. End member mixing analysis (EMMA) was able to predict the storm event concentrations of for four of the six comparisons. Concentrations of at the outlet of the large (696 ha) catchment were much greater than values recorded for the smaller catchments. Exports of in streamflow exceeded the inputs from atmospheric deposition suggesting that watersheds like Point Peter Brook may not show any immediate response to decreases in atmospheric deposition.     

Appropriate Range of Quality Control Limit for Wet Deposition Monitoring

Precipitation chemistry programs in different regions of the world have different quality control limits for ion balance parameter IPD in wet deposition monitoring (R). The range of R values was calculated by assuming sample rainwater models in this paper. It was found that R was influenced by the inorganic ion types, total ion concentrations (IS) and the accuracy of the measurements (a _i ). R was defined and calculated as a function of a _i and ion concentration C _i . R values of different types of wet deposition (including ocean type, continent type and combined oceanic and continental deposition) were different. There were also differences between the samples of the same type if the samples had different total ion concentrations. When IS>100 μeq/L, the ranges of R of ocean type deposition, continent type deposition and combined oceanic and continental deposition were 5∼7%, 5∼9% and 5∼11%, respectively. When IS<50 μeq/L, if a _i was 100%, the range of R was 33∼71% because of the lower accuracy. It was also found that R of each criterion was in the range of R as calculated in this paper when IS≥50 μeq/L, but when IS<50 μeq/L, the criteria varied greatly in their R values.     

Characteristic Study of Dry Deposition, Concentration, Compositions for Particulates Mass and Ionic Species During Summer and Autumn Season at a Traffic Sampling Site

Aerosol samples for dry deposition and total suspend particulates (TSP) were collected from August to November of 2003 in central Taiwan. Ion chromatography was used to analyze the related water-soluble ionic species (Cl⁻, NO₃ ⁻, SO₄ ²⁻, Na⁺, NH₄ ⁺, K⁺, Mg²⁺ and Ca²⁺). The results obtained in this study indicated that the ambient air particulate mass concentrations in the daytime period (averaged 975.4 μg m⁻³) were higher than the nighttime period (averaged 542.1 μg m⁻³). And the daytime dry deposition fluxes (averaged 58.12 μg m⁻² sec⁻¹) were about 2.2 times as that of nighttime dry deposition fluxes (averaged 26.54 μg m⁻² sec⁻¹) of the downward dry deposition. The average values downward and upward of dry deposition fluxes for the weekend period were almost higher than the weekday period for either daytime or nighttime period. Furthermore, the average daytime dry deposition fluxes (averaged 26.37 μg m⁻² sec⁻¹) were also about 2.3 times as that of nighttime dry deposition fluxes (averaged 11.52 μg m⁻² sec⁻¹). Moreover, the results also indicate that SO₄ ²⁻ and Ca²⁺ have higher average composition for total suspended particulates in the daytime period while Ca²⁺, SO₄ ²⁻, and Na⁺ have the higher average composition for total suspends particulates in the nighttime period.     

The effect of atmospheric pollution on α-glycerophosphate dehydrogenase activity in the satin moth (Leucoma salicis (L.))

The purpose of this study was to investigate how various combinations of atmospheric pollutants may affect -GPDH activity in the satin moth. Enzyme activity was measured in crude larva and pupa as well as in hoogenates from the fat body and thoracic muscles of adults. The insects were divided into five groups and treated with dust (containing heavy metals) and gaseous pollutants (SO₂, NO_x) in different concentrations. Specific activity of -GPDH was the highest in thoracic muscles of adult satin moth and was significantly higher in males, regardless of their origin. Low concentration of SO₂ caused stimulation of enzyme activity but simultaneous action of SO₂, NO_x and heavy metal containing dust with accompanied acid precipitation caused inhibition of -GPDH activity, probably as the result of sulphite bounds with pyridine and flavin nucleotides.     

Controls on Mercury and Methylmercury Deposition for Two Watersheds in Acadia National Park, Maine

Throughfall and bulk precipitation samples were collected for two watersheds at Acadia National Park, Maine, from 3 May to 16 November 2000, to determine which landscape factors affected mercury (Hg) deposition. One of these watersheds, Cadillac Brook, burned in 1947, providing a natural experimental design to study the effects of forest type on deposition to forested watersheds. Sites that face southwest received the highest Hg deposition, which may be due to the interception of cross-continental movement of contaminated air masses. Sites covered with softwood vegetation also received higher Hg deposition than other vegetation types because of the higher scavenging efficiency of the canopy structure. Methyl mercury (MeHg) deposition was not affected by these factors. Hg deposition, as bulk precipitation and throughfall was lower in Cadillac Brook watershed (burned) than in Hadlock Brook watershed (unburned) because of vegetation type and watershed aspect. Hg and MeHg inputs were weighted by season and vegetation type because these two factors had the most influence on deposition. Hg volatilization was not determined. The total Hg deposition via throughfall and bulk precipitation was 9.4 μg/m²/year in Cadillac Brook watershed and 10.2 μg/m²/year in Hadlock Brook watershed. The total MeHg deposition via throughfall and bulk precipitation was 0.05 μg/m²/year in Cadillac Brook watershed and 0.10 μg/m²/year in Hadlock Brook watershed.     

The development of loads of cations, anions, Cd and Pb in precipitation and of atmospheric concentrations of N-components, in Switzerland from 1988 to 2003

This study presents the results of the analyses of Cd, Pb, cations and anions present in precipitation and dust at a pre-alpine and a suburban site in Switzerland in the period from 1988 to 2003. The aim of these measurements was to monitor the success of measures taken to diminish pollutant emissions. No change was found for Ca²⁺, K⁺, Na⁺ and Mg²⁺ loads – in line with expectations, as no reducing measures had been taken. Statistically significant and largely decreasing values (50–90%) were found for Cl⁻ and Cd (linked to the fitting of filters in incineration plants), Pb (unleaded petrol), (diminishing the use of mineral oil with high S content), and the proton (lower HCl and SO₂ emissions). A smaller decrease (up to 30%) or none was registered for oxidised nitrogen components (fitting cars with catalytic converters, but an increase in numbers of cars and trucks). No significant change was found for NH₃ as farming techniques had undergone no major changes. The long-term measurements show that the measures taken to reduce emissions were successful. A shorter monitoring period would have been misleading owing to data variability and temporary incidents e.g. amount of precipitation.     

A Comparison of Precipitation Sensors Used on the Wet-Only Collectors

The variability in performance of three precipitation sensor types, mounted on three identical wet-only collectors, has been compared for eight months at a single site. The catch efficiencies, determined from the sample volumes, are relatively high for these three apparatuses, since they exceed 89% on average. The recorded data of openings and closings of collector lids reveal that the highest losses of collection efficiency, observed for rainfalls of low intensity and low amount, are largely imputable to design and running characteristics of each sensor. Ionic compositions between the samples of these three collectors are relatively close, although significant differences are especially found for H⁺, Ca²⁺, Mg²⁺ and K⁺, suggesting that these apparatuses are differently exposed to the dry deposition of soil particles. The RS 85 sensor seems to be the most suitable one of the three, since it ensures a high catch efficiency for all rain types and tends to limit the exposures of funnel to the dry deposition.     

Observational and modeling study of dry deposition on surrogate surfaces in a South China city: implication of removal of atmospheric crustal particles

Dry deposition samples collected during 1999–2001 at a South China site using surrogate surfaces were analyzed by capillary electrophoresis. Collector surface properties played important roles to the dry deposition. The deposition velocities for various species ranged from 0.02 to 1.69 cm s^???1, in general agreement with literature values. More than 90% of Ca^2?+? was deposited by sedimentation and its comparable values of dry or wet removal residence times imply that dry deposition is an important atmospheric removal process for the ubiquitous crustal species in South China, compared with precipitation scavenging. Relatively good agreement was found when the species deposition velocities were modeled based on up-to-date knowledge of particle dry deposition. The total depositions for anthropogenic and crustal species in northern China are likely to be much higher than those in the south, including our site where the fluxes of the acidic species SO₄ ^2??? and NO₃ ^??? were 4.4 and 2.2 g m^???2 year^???1, respectively. The sum of dry deposition for cations Na^?+?, Ca^2?+?, Mg^2?+?, and K^?+? contributes 44% of the total flux, which is equivalent to the value estimated in Europe.     

The Precision of Precipitation Chemistry Measurements in the Canadian Air and Precipitation Monitoring Network (CAPMoN)

Precision estimates are presented for precipitation chemistry and depth measurements made by the Canadian Air and Precipitation Monitoring Network (CAPMoN). The estimates were made for daily measurements of ion concentration and precipitation depth as well as for weekly, 28-day, seasonal and annual precipitation-weighted mean concentrations and depths. The data on which the estimates are based were collected from collocated samplers at five CAPMoN sites during the period 1985 to 1993. The data pairs from the collocated samplers were used to calculate the between-instrument error defined as 1/2 times the difference between the paired sample concentrations (or depths). For all of the ion concentrations and depths, the between-sampler errors were found not to be normally distributed, but the normality of the distributions improved with the length of the (volume-weighting) time period considered. A set of quantitative measures of overall network precision were derived in absolute (mg L^-1) and relative (%) units. These included the Modified Median Absolute Deviation (M.MAD), the P90% probability values and the Coefficient of Variation (CoV). The latter, defined as the percent ratio of the M.MAD to the median concentration (or depth), represents the relative precision at the center of the error and concentration (and depth) distributions. Based on the CoV values, the relative precision of the CAPMoN measurements was very high (better than 4%) for SO ₄ ^2- , NO ₃ ^- , pH, H⁺, NH ₄ ⁺ , sample depth and standard gauge depth, and not as high (between 10 and <35%) for Cl^-, Na⁺, Ca²⁺, Mg²⁺, and K⁺. The ions with the lowest median concentrations had the poorest relative precision since so many of the concentrations were at or near the analytical detection limit. Except for the sample and standard gauge depths, both the absolute and relative precision improved with the length of the precipitation-weighting period. Detailed statistical testing established that the precision of the daily measurements is dependent on a number of factors, the most dominant being sample depth and concentration, i.e., the absolute precision improves with increasing sample depth and decreasing concentration. The strength of these relationships diminished with the length of the precipitation-weighting period being considered. Laboratory-related sources of imprecision were found to account for less than 4% of the overall daily measurement imprecision for most species, while field-related sources of imprecision accounted for the balance. Specialized plots are shown which allow data users to estimate the absolute and relative precision at any concentration and depth value.     

Variation in biochemical constituents and master elements in common seaweeds from Alexandria Coast,Egypt, with special reference to their antioxidant activity and potential food uses: prospective equations

Biochemical constituents and master elements (Pb, Cr, Cd, Fe, Cu, Zn, Hg, B, Al, SO₄ ^2?, Na, K, Li, Ca, Mg, and F) were investigated in six different seaweed species from Abu Qir Bay in the Egyptian Mediterranean Sea coast. The moisture level ranged from 30.26% in Corallina mediterranea to 77.57% in Padina boryana. On dry weight basis, the ash contents varied from 25.53% in Jania rubens to 88.84% in Sargassum wightii. The protein contents fluctuated from 8.26% in S. wightii to 28.01% in J. rubens. Enteromorpha linza showed the highest lipids (4.66%) and carbohydrate contents (78.95%), whereas C. mediterranea had the lowest lipid (0.5%), and carbohydrate contents (38.12%). Chlorophylls and carotenoid contents varied among the species. Total antioxidant capacity of the tested green seaweeds had the highest activities followed by brown and red seaweeds which had a similar trend of phenol and tannins contents. High reducing power was observed in all tested seaweeds extract except Ulva lactuca. Brown species had the highest amount of elements followed by red and green seaweeds. Notably, SO₄ ^2? recorded the highest level in the tested green species (108.05 mg/g dry weight (DW)). The Ca/Mg and K/Na ratios reflected highly significant difference between seaweed species. This study keeps an eye on 29 parameters and by applying stepwise multiple regression analysis, prospective equations have been set to describe the interactions between these parameters inside seaweeds. Accordingly, the tested seaweeds can be recommended as a source of healthy food with suitable ion quotient and estimated daily intake values.     

Monitoring the results of Canada/U.S.A acid rain control programs: some lake responses

Aquatic acidification by deposition of airborne pollutants emerged as an environmental issue in southeastern Canada during the 1970s. Drawing information from the extensive research and monitoring programs, a sequence of issue assessments demonstrated the necessity of reducing the anthropogenic emissions of acidifying pollutants, particularly sulphur dioxide (SO₂). The 1991 Canada-U.S. Air Quality Agreement (AQA) was negotiated to reduce North American SO₂ emissions by 40% relative to 1980 levels by 2010, and at present, both countries have reduced emissions beyond their AQA commitment. In response to reduced SO₂ emissions, atmospheric deposition of sulphate (SO₄ ^2–) and SO₄ ^2– concentrations in many lakes have declined, particularly in south-central Ontario and southern Québec. Sulphate deposition still exceeds aquatic critical loads throughout southeastern Canada however. Increasing pH or alkalinity (commonly deemed recovery) has been observed in only some lakes. Several biogeochemical factors have intervened to modify the lake chemistry response to reduced SO₄ ^2– input, notably release of stored SO₄ ^2– from wetlands following periods of drought and reduction in the export of base cations from terrestrial soils. Three examples from Ontario are presented to illustrate these responses. Significant increases in pH and alkalinity have been observed in many lakes in the Sudbury area of Ontario due to the large reductions in local SO₂ emissions; early-stage biological recovery is evident in these lakes. An integrated assessment model predicts that AQA emission reductions will not be sufficient to promote widespread chemical or biological recovery of Canadian lakes. Monitoring and modeling are mutually supporting assessment activities and both must continue.     

Environmental Assessment of the Impact of Ozone to the Neuston of the Sea-Surface Microlayer of the Gulf of Mexico

Substantial amounts of NOx (146 000 t/y) and total hydrocarbons (294 000 t/y) are released to the marine atmosphere by the large number of oil and gas operations over Federal waters of the Gulf of Mexico (GOM). Under appropriate meteorological conditions these emissions react to form ozone (0–54 g/m3 over-water) which can affect the marine environment. Using a dry deposition model, this work examines the amount of ozone derived from oil and gas offshore operations and deposited in the sea surface of the Gulf of Mexico, and assesses its impact on the neuston of the sea-surface microlayer. Surface integrated estimates of ozone deposited from oil and gas operations over the sea surface ranges from 400 kg to 1800 kg which results in sea surface concentrations of 15 g/m3. This estimate and the actual toxic ozone levels suggest no acute, toxic impacts to the neuston. However, indirect effects may occur through changes to the pelagic foodwebs and organic carbon pathways. Another potential pathway for ozone impacting the environment is through the production of bromate. Based on the concentrations and time scales (11–139 days) only sublethal effects appear to occur, but uncertainties associated with this assessment need to be further studied. From an ecological perspective, the environmental impacts and risks of NOx and VOC discharges from offshore platforms need to be assessed for neuston and other components of the marine ecosystem.     

Dynamics of atmospheric polychlorinated biphenyls (PCBs): concentrations, patterns, partitioning, and dry deposition level estimations in a residential site of Turkey

Air samples were collected at a residential site (Gulbahce, Bursa, Turkey) between August 2004 and April 2005 using a modified high volume air sampler. The mean of gas and particle phase concentrations of polychlorinated biphenyls (PCBs) were 468 ± 297 and 43 ± 37 pg m^???3 (average ± standard deviation, SD), respectively. The dominated PCB homologs were 3-CBs, 4-CBs, and 5-CBs. The measured PCB concentrations were higher than the values of pristine sites. In order to assess the gas/particle partitioning fate, log K _P–log $P_{\rm L}^o$ , log K _P–log K _OA and the Junge–Pankow model were applied to the data. Experimental K _P was well correlated with $\log P_{\rm L}^o$ and log K _OA at p?<?0.05. Then, dry deposition fluxes were estimated using atmospheric concentrations and dry deposition velocities obtained from literature. A correlation matrix was formed for PCB homologs including 27 congeners with concurrently measured 16 polycyclic aromatic hydrocarbons (PAHs) and meteorological parameters. Most of PAH compounds were significantly correlated with 5-CBs and 6-CBs.