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1.
Between December 1986 and June 1987, the mean pH of rainfall downwind of the Kilauea main vent was found to be 4.5 (range 4.0 to 5.6), 1.2 units higher than the year before (1985-86), although 84% of the 12 sequential samples fell below pH 5.0. The SO4 content, however, was 34% higher, averaging 18.5 mg L?1. Upwind, in open forest the mean pH 4.7 was little changed from that measured before. Mean SO4, however, has fallen to a low of 2.5 mg L?1, but, more significantly, in 9 out of 12 sequential samples S04 was not detectable at all (i.e. < 0.5 mg L?1). The calculated pH, assuming 100% H2SO4 would be 5.3 yet 58% of these samples fell below pH 5.0, the lowest being 4.0. Disparities between pH measured and calculated on the basis of SO4 content indicated that other acid species were present in the precipitation. Oxidation of rain samples with H2O2 greatly increased SO4 content and lowered pH downwind, but failed in most samples to alter either parameter in the upwind collections. These observations, together with the elimination of HCl and N03 by others, suggested that SO2 contributes significantly to acidity downwind, but that in most upwind samples a source of H+ other than mineral acids, presumably organic compounds, must be of major importance.  相似文献   

2.
A method to determine pyrophosphate (PP) and tripolyphosphate (TPP) in sediments was developed. Sediment was extracted with 2% EDTA + 0.1 M NH4F followed by a second extract of 2% EDTA + 1 N NaOH. Orthophosphate (OP), PP, and TPP were separated by anion exchange chromatography, the fractions collected, and P determined after extraction into isobutanol. The limit of detection of the method was 0.5 μg P g?1 sediment. Fourteen sediments were tested and the highest TPP found was 1.8 μg P g?1 sediment. Thirteen of the sediment samples contained less than 1 μg P g?1 as TPP. Only three of the 14 samples contained more than 1 μg P g?1 as PP. The highest level of PP (8.5 μg P g?1) was found in sediment from an animal waste lagoon. Estimates of error and reproducibility were made from analysis of samples with added PP and TPP. The error for samples containing 36.9 μg P g?1 as PP was ± 7.6, and for TPP at 12.3 μg P g?1 the error was ± 3.3. The values for PP and TPP were underestimated by 6 and 36%, respectively.  相似文献   

3.
There is a declining gradient of wet SO4 deposition from south to north in Nova Scotia with the highest values being in the south, along with a localized increase around the Halifax metropolitan area, due to local SO4 emission. Edaphic conditions such as drainage from soils containing gypsum or drainage on disturbed rocks containing pyrite, provide additional SO4 to surface waters.Acidity is usually absent in the former (pH > 7.0) and very high in the latter (as low as pH 3.6). By contrast peaty, organic drainages release water low in SO4 during the growing season but they release high amounts of organic anions (A?), consequently, these waters maintain decreased pH values, usually < 4.5. A study of over 80 wetlands and lakes during the ice free period in Nova Scotia showed that sea salt corrected SO4 concentrations range from 45 ueq L?1 in the south end of the province, ～30 ueq L?1 in the Kejimkujik area and < 17 ueq L?1 in the northern areas with values > 85 ueq L?1 in the Halifax area, reflecting the atmospheric deposition pattern of SO4 The SO4 concentrations may be > 2000 ueq L?1 in drainages containing gypsum, > 700 ueq L?1 in drainages over pyrite bearing socks but < 20 ueq/L?1 in streams draining bogs. The SO4 concentrations change considerably during the non-growing season when the ground is saturated with water or frozen, and the runoff is high (snow and rain often alternate in winter). Under such conditions SO4 concentration drops in the two former cases and increases in bog drainages, accompanied with a considerable drop in (A?) concentrations. Care should be taken when interpreting SO4 concentrations in surface waters in Nova Scotia with respect to atmospheric SO4 deposition.  相似文献   

4.
The Hg concentrations in coal as fired in power plants in the Netherlands are low, 0.2 mg·kg?1 on average. After combustion the Hg is released partly (between 1 and 98%, on average 42%) in a gaseous phase, which is finally emitted into the air. The other part of the Hg, which remains in the ash is separated from the flue gases by electrostatic precipitators. The variation of the vaporisation percentage of Hg is probably caused by the presence of two chemical forms: Hgo and HgCl2. This may be concluded from the observation that relatively high concentrations of HCl in the flue gases (≈150 mg·m?3) give rise to low Hg concentration in the vapor phase. In cases when the concentrations of HCl are relatively low (≈25 mg·m?3) the amount of Hg in the vapor phase is high. The average gas phase concentrations of Hg in the flue gases, based on 33 measurements with no FGD, is 4.1 μg·mfo ?3. In a wet FGD based on the lime/limestone-gypsum process 50 to 70% of the Hg in the flue gases is removed, leaving a residual concentration of 1–2 μg·mfo ?3. The emission factor is then about 0.5 mg·GJ?1 or 5 μg·kWhr?1. In one particular measuring serie the fate of Hg was studied in a FGD-installation with a prescrubber.  相似文献   

5.
Rain and snow were collected in plastic beakers either manually or with a Wong sampler during 58 precipitation events in 1974 at Yonkers, New York approximately 24 km north of the center of New York City. Determinations were made of total dissolved ionic species, free H ions, total H ions, sulfate, nitrate, chloride, and fluoride. Conductivity measurements ranged from 6.8 to 162 gmhos, pH from 3.4 to 4.9, total acidity from 36 to 557 μeq 1?1 sulfate from less than 1 to 20 mg 1?1, nitrate from less than 1 to 14 mg 1?1, and chloride from less than 1 to 7 mg 1?1. All fluoride concentrations were less than 0.1 mg 1?1. The results indicate that precipitation at this suburban location adjacent to New York City is consistently acidic and contains concentrations of sulfate, nitrate, and chloride which are similar to values found for other locations in the northeastern United States. Positive correlations were found between nitrate and sulfate concentrations and acidity suggesting that the atmospheric contaminants, SO2, and NO2 are causally-related to the occurrence of acidic precipitation. Further research will be necessary to clarify the relative influence of natural and man-made sources of N and S compounds and the contributions of gaseous and particulate contaminants in the atmosphere to the acidity of precipitation at this location.  相似文献   

6.
Atmospheric air pollution levels and long-term effects on the environment caused by simultaneous presence of SO2 and oil shale alkaline fly ash during the last five decades (since 1950) were investigated. The annual critical value of SO2 for forest (20 µg m?3) was surpassed in 1% (～35 km2) of the study area where the load was 30–40 µg m?3. No effect of long-term SO2 concentrations of up to 10–11 µg m?3 (0.5-h max up to 270 µg m?3) and simultaneous fly ash loads of up to 95 µg m?3 (1000 µg m?3) on the growth and needle longevity of Pinus sylvestris was established. The yearly deposition (average load up to 20–100 kg S ha?1) was alkaline rather than acidic due to an elevated base cation deposition in 1960–1989. Since 1990, the proportion of SO2 in the balance of components increased: about 70–85% of the total area was affected while the ratio of annual average concentrations of SO2 to fly ash was over 1. The limit values of fly ash for Sphagnum mosses and conifers in the presence of SO2 are recommended.  相似文献   

7.
Laboratory-scale models consisting of a simple upflow anaerobic sludge blanket reactor (UASBR) and an upflow anaerobic filter (UAF) in series were subjected to organic loadings of 0.19 to 0.55 kg COD m?3 d?1 at 20°C. COD and SS removals were 95 to 98% and 98 to 99%, respectively. Biogas produced by the system amounted to 0.31 to 0.32 m3 CH4 kg?1 COD removed. The UASBR was more stable than the UAF in performance. No sign of deterioration in final effluent quality was observed during 420 days of operation under low loading.  相似文献   

8.
Litter decomposition was studied at two forested watersheds in east Tennessee which differed primarily in their past history of atmospheric S input. Cross Creek Watershed, located near a large coal-fired power plant, has received greater S inputs than the more remote Camp Branch Watershed. Decomposition was estimated through the measurement of forest floor respiration, litter microflora populations, litter and soil microarthropod populations, and litter nutrient status. Average forest floor respiration rates were very similar, 6.78 g CO2 m?2 day?1 or 2472 g m?2 yr?1 at Camp Branch and 6.86 g CO2 m?2 day?1 or 2505 g M?2 yr?1 at Cross Creek. Fractional loss rates provided estimates of annual decay rates (k) of 0.35 and 0.39 for Camp Branch and Cross Creek, respectively. Litter decomposition was estimated to contribute 23% of the total CO2 output at Camp Branch and 26% at Cross Creek, while root respiration accounts for about 43 to 46%. Bacterial and fungal populations were about equal in size at both watersheds, with bacteria averaging 100 × 106 g?1 of litter and fungi 23 × 106 g?1 of litter. Total numbers of arthropods averaged 34% greater at Camp Branch. Acarina populations averaged 59% higher at Camp Branch, while Collembola numbers were about equal at the two watersheds. Nutrient mobility in the litter and soil was similar at both watersheds. The order of decreasing mobility was K, Mg, Ca, S, N, and P. Litterfall nutrient concentrations were slightly higher for all elements at Cross Creek, resulting in greater litter concentrations of Ca and Mg. Litter concentrations of S and N, however, were significantly greater at Camp Branch, indicating watershed differences in the loss rates and cycling processes of these elements. There were no differences between the loss rates or litter concentrations of P, K, and Na at either site. Overall, decomposition was similar at the two watersheds. Historic S inputs do not appear to have had a major effect on decomposition rate or decomposer organisms with the possible exception of lowered arthropod populations at Cross Creek.  相似文献   

9.
The investigation of SO2, NO2, soot and benzo(a)pyrene (BP) has been performed at the background station on the eastern coast of the Baltic Sea since 1980. A significant decreasing trend has been observed for SO2 and NO2, while soot and BP concentrations were changing insignificantly. The decreasing SO2 and NO2 high concentrations (>10µg·m?3) have been determined in the air masses coming from the Western and Central Europe to Lithuania since 1900. The concentration of SO2 in a range of 0–5µg·m?3 and the concentration of NO2 in a range of 0–10µg·m?3 are characteric of the background atmospheric air.  相似文献   

10.
The hydrobiological parameters of the waters in the vicinity of ash slurry and cooling water outfall from Ennore Thermal Power Station located on the shore of Bay of Bengal, Madras were determined. In the outfall site, an increase in mean temperature (35 °C), salinity (3.5%), nitrite ? N (25 μg L?1), ammonia ? N (185 μg L?1), phosphate ? P (1 mg L?1), silicate ? SiO2 (1.65 mg L?1), chlorophyll a (21.1 mg m?3), respiration (76% of gross production), suspended solids (3.84 g L?1), BOD (3.65 mg O2) and decrease in pH (8.1), dissolved oxygen (DO) (5.5 mg L?1), nitrate ? N (15 jig L?1), gross production (16.6 Mg C m?3 hr?1) were recorded. Phaeopigment and respiration were inversely related with chlorophyll a and net productivity, respectively. Microbial biomass varied spatially, but was generally low (114.5 jig L?1), at the outfall site. The hydrobiological characteristics of water with high turbidity indicate that the ash slurry and coolant water play a crucial role in a localized area resulting in environmental disturbance. The effect was profoundly influenced by an initial dilution, dispersion, wave mixing and current direction. The ecological relationships between these parameters and their implications in coastal pollution are discussed.  相似文献   

11.
Clarias anguillaris and Oreochromis niloticus were each exposed to solutions of Analar grade Cu sulphate in static bioassays at a temperature range of 20 to 23.5°C and CaCO3 hardness of 30 to 44 mg L?1. Copper accumulation was determined by Atomic Absorption Spectroscopy. The Cu residues in Clarias anguillaris exposed to 0.027, 0.055, and 0.11 mg Cu L?1. for 8 weeks were 15.7, 21.8, and 31.17 mg g?1 dry weight, respectively. Oreochromis niloticus exposed to 0.05, 0.1 and 0.2 mg Cu L?1. accumulated 34.69, 36.09, and 81.03 mg g?1 dry weight, respectively, over the 8-week period of exposure. The lowest and highest bioconcentration factors (BCF) were 117 and 581 for Clarias anguillaris and, 176 and 694 for Oreochromis niloticus. Copper concentrations in tissues of both species were directly related to the exposure concentrations and the duration of exposure. Increased accumulation towards the last 2 weeks of exposure may be due to impaired capacity of elimination or poor nutritional status.  相似文献   

12.
Precipitation chemistry data were collected at 8 sites in the western part of the Netherlands over a period of 151/2 yr. Using specially-designed wind direction-dependent rain collectors, it is demonstrated that levels of ion constituents in rain water vary with wind direction, which can be assigned to different sources of contamination. The strongest variation was measured for Na+. As expected, trajectories over sea contributed most. Continental sources slightly reduced the variation for Cl? and Mg2+. For both NH inf4 sup+ and excess SO inf4 sup2? , maxima were found in southeasterly rainfall. It is assumed that polluted air from the large industrial Ruhr Area crosses a region with strong NH3 emissions in the Southeast of the Netherlands. The presence of ammonium sulfate was suggested. Minor variations were measured for NO inf3 sup? (due to diffusely-spread emissions and possible sampling artefact) and for H+ and Ca2+ (dry-deposition effects). Over the period 1973–1987 excess-SO inf4 sup2? levels decreased significantly (?3.3% yr?1, p<0.01) which is consistent with reduced S emission in Western Europe. Over the last decade an upward trend in NO inf3 sup? levels has been observed (3.2% yr?1, p<0.05) which is possibly related to the increased usage of cars.  相似文献   

13.
The occurrence and characteristics of chemically-based density stratification in portions of the Seneca and Oswego Rivers, downstream of ion-polluted Onondaga Lake, are described for seven different days in the summer and fall of 1978 and 1981, which covered a wide range of river flows. The results indicate that chemically-based density stratification occurs routinely in the Seneca River downstream of the lake inflow, in response to a continuous chemically-based density difference between the two systems of 0.0015 to 0.0030 g cm?3. The persistence of the phenomenon, and therefore the longitudinal range over which the river stratification occurred, was dependent on the velocity of river flow and the magnitude of the density gradient that bordered the upper river water and the lower released lake water. During the low flows common to summer the stratification extended approximately 14 km downstream to a dam, and 3 km upstream, of the lake outlet — river junction. Vertical mixing between the stratified layers increased as the flow in the Seneca River increased, and as the vertical density gradient decreased. A dimensionless group, $$\frac{D}{{V\left( {\frac{\rho }{{\Delta _\rho /\Delta _z }}} \right)}}$$ where: D = apparent vertical diffusion (m2 hr?1), V = average velocity of the overlying river flow (m hr?1 ), p = density at the interface between the stratified layers (g cm?3), and Ap/Az = density gradient between the stratified layers (g cm?3 m?1), was found to be constant for summer low flow conditions for a 6.5 km length of the Seneca River, thus quantifying the interaction between vertical mixing and the included influences for that portion of the river. The occurrence of chemical stratification in the river had dramatic implications on the corresponding distribution of dissolved oxygen (DO). The isolation of the organically enriched lake water in the lower layer enhanced the depletion of DO there, which resulted in the development of substantial (> 4.0 mg 1?1 ) DO stratification downstream of the discharge from the lake during summer low flow periods.  相似文献   

14.
Radiotracer experiments on the sorption of I? (iodide) and IO inf 3 p? (iodate) from water by soils such as field soil, rice paddy soil and sandy soil, as well as by some soil components, have been carried out with special reference to the effects of heating and gamma-irradiating the soil. Desorption phenomena of I from soil to various solutions were also studied. The sorption of I? by soil was markedly reduced through treatments of air-drying and heating the soil prior to its equilibration with water. The results indicated that I? sorption was by the soil fraction which was unstable at about 150 °C, while IO inf 3 p? sorption was by the soil fraction which was relatively stable to heating. Gamma-irradiation at 27 kGy affected the sorption to a smaller extent than heating at 150 °C. A very high sorption (or soil-water distribution coefficient, Kd) was found in untreated field soil (andosol) with a low organic C (humus) content, while the sorption by sandy soil was considerably smaller than the other soils. Neither I? or IO inf 3 p? were well sorbed by clay minerals, Al2O3 and quartz sand, while the sorption by Fe2O3 was IO inf 3 p? were desorbed by 1N NaOH solution. By acidifying this solution, only a part of the desorbed I was re-precipitated with humic acid. The desorption by solutions containing K2SO3 or KI was also high, while that by solutions containing HCI, CH3COONH4 or chemical fertilizer was considerably lower. These findings suggested the possibility that I was not directly associated with humic acid itself.  相似文献   

15.
The SO2 emissions from the Kola Peninsula in Arctic Russia (totalling around 600 Gg(SO2) yr–1 at the beginning of the 1990s) produce an atmospheric SO2 concentration gradient to the northernmost Europe. This gradient covers the range from >50 g m–3 in the vicinity of the sources to 1 g m–3 in Finnish Lapland. In the present study, the measured sulphur concentrations in Scots pine needles were compared with the estimated distribution of atmospheric SO2. The total sulphur concentrations in the needles ranged from 741 to 2017 mg kg–1. Strongly elevated concentrations (> 1200 mg kg–1) were found within 40 km from the smelters corresponding to an area where the annual mean atmospheric SO2 concentration exceeded 10 g m–3. The foliar sulphur concentrations (total, organic and inorganic) show a high correlation with the estimated mean SO2 concentration distribution in the air. Consequently the foliar sulphur concentrations reflected the atmospheric sulphur load well. The data presented here show that uptake via stomata is an important deposition pathway also in the arctic conditions with a short growing season.  相似文献   

16.
A study on pH and chemical composition of precipitation was carried out in two Italian sites, one urban (site 1) and one rural (site 2), located approximately 30 km far from Bologna, during a 3-year period. No significative site variation was found. In both locations, bulk deposition pH ranged from slightly acid to slightly alkaline, despite the volume weighted mean concentration of acidic species, NO 3 ? and SO 4 2? (67.4 and 118.4 μeq l?1 in site 1 and 88.7 and 103.8 μeq l?1 in site 2), that were similar to those of typical acidic rainfall region. This might be ascribed to the neutralization reaction of the Ca2+, attributed to the calcareous soil and the frequent dusty air mass intrusion from the Sahara. The pair correlation matrix and the analysis of the main components suggested also ammonium and other crustal elements as neutralization agents. The depositional rate of SO 4 2? and NO 3 ? , chemical elements of agricultural interest, amounted to 38 and 28 and 32 and 35 kg ha?1 for site 1 and site 2, respectively. These supplies of nutrient were not negligible and had to be considered on cultivated lands. NH 4 + deposition rate on site 2 was 7 kg ha?1, 23% over site 1, probably due to nitrogen fertilization in the fields around the monitoring station. In site 1, SO 4 2? presented a seasonal trend, indicating that its principal source was the residential heating. Results emphasized that the entity of the bulk deposition acidification is linked not only to the ions local emission sources (fossil fuel combustions, heating, and fertilizers) but also to the surrounding territory and the prevalent wind that transports through kilometers air masses which may contain acidic and alkaline species.  相似文献   

17.
This paper discusses the results of the air quality monitoring activities, especially for three of the Ontario Ministry of the Environment's criteria pollutants (SO2, O3, and total suspended particulates). In the early 1960's Nanticoke Hamlet, located on the northern shore of Lake Erie, was selected for a large industrial development program. The first phase saw the commissioning of a 4000 MW Ontario Hydrothermal generating station, a 100 000 bbl day?1 Texaco refinery and a Stelco steel plant with an initial annual capacity of 1.7 × 106 tonnes. Favorable climatological data was one of the criteria used for selecting this site. Extensive monitoring of ambient air and water quality was carried out prior to the construction phase of the program. Post operation monitoring has also been done on a continuous basis. The data collected to date indicate that the impact of the industrial activity on air quality in the Haldimand-Norfolk region has been very small, with less than 20 exceedances per year of the hourly air quality criterion for SO2 (250 ppb) being observed across the network, and total suspended particulates being similar to other rural locations in Ontario. Only 03 has a substantial number of exceedances of the criterion (80 ppb hourly average) during the summer months, primarily due to long-range transport into the area from across Lake Erie.  相似文献   

18.

Purpose

Middle-European floodplain soils are often contaminated with mercury (Hg) and periodically flooded. In this study, the influence of a flooding event and subsequent dewatering on the volatilization of elemental Hg and methylated species was investigated in a laboratory experiment.

Material and methods

Undisturbed soil cores were taken from a topsoil (12.1?±?0.75 mg kg?1 Hg) at the Elbe River in Lower Saxony, Germany. Soil columns were incubated at 20 °C with varying soil moisture (water-saturated for 2 weeks, 95 and 90 % water content for 1 week each), and the redox potential (EH) was recorded. The gaseous Hg that accumulated in the headspace of the flux chamber of the columns was pumped over cooled traps filled with adsorber material and analyzed by gas chromatography/inductively coupled plasma mass spectrometry for the various Hg species.

Results and discussion

The watering of the soil resulted in a rapid decrease in the EH and the achievement of strongly reducing conditions (EH??1 Hg at the beginning to 5.78 μg L?1 Hg at the end of the experiment. Species analyses revealed that exclusively elemental Hg volatilized. The volatilization rate was between 1.73 and 824 ng m?2 h?1 Hg, which is consistent with other studies at the Elbe River.

Conclusions

Even when flooded for a longer period of time, floodplain soils should show neither emission of methylated Hg nor exceptionally high volatilization of elemental Hg.  相似文献   

19.
The effects of storm dynamics on precipitation chemistry were examined using an atmospheric budget for SO4 ? . One hundred storms occurring between 1975 and 1978 at Hubbard Brook Experimental Forest in New Hampshire were used as test data. Concentrations of major ions were usually greater in convective storms than in continuous or layer storms. For example the geometric mean concentrations of SO4 ? in convective and continuous storms were 4.1 and 1.1 mg L?1, respectively. Higher SO4 ? concentrations also occurred when surface wind directions were south or southwest. The summer maximum in convective activity along with the seasonal dependence of surface wind directions and the seasonal atmospheric chemistry cycle can account for the summer maximum in SO4 ? concentrations observed in the northeastern United States.  相似文献   

20.
Atmospheric gases and particulates were collected using four-stage filter-pack in Chunchon from January through December in 1999. Particulate SO4 2? and NO3 ?, and gaseous HNO3, SO2 and NH3 were analyzed. Annual average concentration of SO4 2?(S), NO3 ?(S), HNO3 (g), SO2(g) and NH3(g) were 5.75µg/m3, 4.98µg/m3, 0.33ppb, 1.52ppb and 7.25ppb, respectively. Annual dry deposition fluxes were estimated using the measured concentration and dry deposition velocity published by other research group. Annual dry deposition of S was 287kg · (km)?2·y?1, which accounted for about 30% of total S deposition. For N deposition, dry deposition is predominant; about 70% of total N deposition was through dry process mostly as forms of NH3 and HNO3.  相似文献   

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