Wet deposition of phosphorus in Florida

Wet deposition of phosphorus was measured at 10 sites across Florida originally established as part of the Florida Atmospheric Mercury Study conducted between 1992 and 1996. Monthly integrated samples were collected and analyzed using a total analytical protocol that incorporated “clean lab” conditions for sample equipment preparation and Aerochem Metrics collectors modified for suitability to use for ultra-trace elements. Samples also were collected aboard 15 m towers to minimize any influence on measured deposition by insects, etc., and locally originating particles that do not contribute to true net deposition. Extensive replication of samples in the field was conducted (ca. 83%). The average absolute difference between replicates was 16.2%, with a median absolute difference of 9.5%. Replicate precision was poorest for concentrations above 0.080 mg P l⁻¹, suggesting that concentrations above this level are contaminated.The wet deposition concentrations and fluxes of phosphorus measured in this study are appreciably lower than those reported by previous investigators for wet deposition in Florida, and lie at the lower end of measurements reported in the recent literature. For example, the volume weighted mean concentration and flux for wet deposition across all our study sites averaged 0.005 mg P l⁻¹ and 7.5 mg P m⁻² yr⁻¹, respectively, which is approximately 50% and 32% lower than that reported by Hendry et al. (1981 in Atmospheric Pollutants in Natural Waters. Ann Arbor Science, Ann Arbor. MI, pp. 199–215). Our lower measurements likely reflect three factors: (1) the ultra-trace element sampling and analytical protocols; (2) improved collector design to eliminate sampling artifacts (e.g., splash-off contamination and transfer of contaminants from the dry bucket); and (3) placement of collectors off the ground surface. Lower VWM concentrations were observed near the Florida coast; otherwise, strong spatial patterns across the state were absent. Seasonal variations in VWM also were not pronounced, although deposition fluxes were highest during the summer wet season in response to the strong seasonal distribution of rainfall.     

棕刚玉渣的硬脂酸湿法改性

以棕刚玉渣、硬脂酸为原料,在乙醇体系中进行机械力化学改性研究。分别研究了球磨过程中球料比、球磨时间、转速、硬脂酸用量、浆料浓度等参数对实验样品亲油化度、活化指数的影响。在最佳工艺基础上进行了正交实验,实验结果表明,适宜条件为硬脂酸用量3.5%,球料比4∶1,球磨时间30 min,球磨转速450 r/min,浆料浓度25%时,实验样品的亲油化度和活化指数分别达到46.8%和100%,且完全疏水。     

Wet and dry deposition of trace elements onto the Greenland ice sheet

Trace element concentrations have been measured in the air and in fresh and older surface snow during the summers of 1978 and 1979 at Dye 3, south-central Greenland. These data have been used with other information in the literature to calculate a total (wet plus dry) deposition velocity on the order of 0.5 cms⁻¹ for trace element transport to the ice sheet on an annual basis. The data suggest that dry deposition contributes less than 25 % of the total transport for elements with large enrichment factors. Crustal elements may be more significantly influenced by dry deposition.     

Wet deposition of poly- and perfluorinated compounds in Northern Germany

Twenty precipitation samples were taken concurrently with air samples at a northern German monitoring site over a period of 7 months in 2007 and 2008. Thirty four poly- and perfluorinated compounds (PFC) were determined in rain water samples by solid phase extraction and HPLC-MS/MS analysis. Seventeen compounds were detected in rain water with ΣPFC concentrations ranging from 1.6 ng L⁻¹ to 48.6 ng L⁻¹. Perfluorooctanoate (PFOA) and perfluorobutanate (PFBA) were the compounds that were usually observed in highest concentrations. Calculated ΣPFC deposition rates were between 2 and 91 ng m⁻² d⁻¹. These findings indicate that particle phase PFC are deposited from the atmosphere by precipitation. A relationship between PFC wet deposition and air concentration may be established via precipitation amounts. Trajectory analysis revealed that PFC concentration and deposition estimates in precipitation can only be explained if a detailed air mass history is considered.     

Wet and dry deposition of sulfur and nitrogen compounds in Ontario

Measurements have been made of sulfur and nitrogen compounds in precipitation since 1980 and in air since 1981 in Ontario. This paper presents results of the atmospheric deposition measurement program to the end of 1985. As is to be expected from the distribution of emission sources, annual concentrations of SO₄²⁻ andNO₃⁻ in precipitation, and of SO₂,SO₄²⁻ andNO₃⁻ in air are higher in southern Ontario than in northern Ontario. The corresponding distribution pattern for deposition is similar to that of concentration. A wet SO₄²⁻ deposition rate of 20 kg ha¹⁻ y¹⁻, a value considered critical for the acidification of sensitive water bodies, is exceeded in all of central and southern Ontario. On a province-wide basis, sulfur wet deposition is about four times higher than sulfur dry deposition. For nitrogen, wet and dry deposition are more comparable, though the former is still higher. The S- and N-species display different seasonal trends in concentration and deposition reflecting a dependence on meteorological factors, and on the associated chemical transformation rates. On the other hand, year to year variations are small.     

Wet deposition of mercury within the vicinity of a cement plant before and during cement plant maintenance

Hg species (total mercury, methylmercury, reactive mercury) in precipitation were investigated in the vicinity of the Lehigh Hanson Permanente Cement Plant in the San Francisco Bay Area, CA., USA. Precipitation was collected weekly between November 29, 2007 and March 20, 2008, which included the period in February and March 2008 when cement production was minimized during annual plant maintenance. When the cement plant was operational, the volume weighted mean (VWM) and wet depositional flux for total Hg (Hg_T) were 6.7 and 5.8 times higher, respectively, compared to a control site located 3.5 km east of the cement plant. In February and March, when cement plant operations were minimized, levels were approximately equal at both sites (the ratio for both parameters was 1.1). Due to the close proximity between the two sites, meteorological conditions (e.g., precipitation levels, wind direction) were similar, and therefore higher VWM Hg_T levels and Hg_T deposition likely reflected increased Hg emissions from the cement plant. Methylmercury (MeHg) and reactive Hg (Hg(II)) were also measured; compared to the control site, the VWM for MeHg was lower at the cement plant (the ratio = 0.75) and the VWM for Hg(II) was slightly higher (ratio = 1.2), which indicated the cement plant was not likely a significant source of these Hg species to the watershed.     

The use of weather radar in assessing deposition of radioactivity from chernobyl across England and Wales

Deposition of radionuclides from the Chernobyl accident depended critically on patterns of precipitation intercepting the material. This paper describes the use of the RAINPATCH model to calculate wet deposition of ¹³⁷Cs over England and Wales. This puff-based model makes direct use of precipitation data measured by weather radar to determine the scavenging of airborne material. The detailed spatial and temporal resolution of when and where material was scavenged provides good agreement with measurements. Since all the data used could potentially have been available at the time, such methods could usefully be applied in real time in the event of any future accident releasing such radionuclides.     

Wet deposition of low molecular weight mono- and di-carboxylic acids,aldehydes and inorganic species in Los Angeles

About 60 rainwater samples were collected at west Los Angeles, California in 1981–1984 and were analyzed for C₁–C₉ monocarboxylic acids (0.33–79 μM, average (av.) 13±15 μM), C₂–C₁₀ dicarboxylic acids (2.9–51 μM, av. 7.5±14 μM) and C₁–C₄ aldehydes (0.85–28 μM, av. 9.2±11 μM). Distributions of monocarboxylic acids show a predominance of formic (average concentration: 6.5 μM) and acetic (av. 5.6 μM) acids followed by propionic acid (av. 0.44 μM). Oxalic acid is the dominant diacid (av. 3.9 μM) followed by succinic acid (av. 1.0 μM). Formaldehyde (av. 6.9 μM) is the dominant aldehyde, with the next most abundant, acetaldehyde, being minor (av. 0.65 μM). For select rain samples described in this paper, were found to comprise monocarboxylic acids 0.9–12.3% (av. 4.4±3.4%), diacids comprise 1.2–9.5% (av. 4.2±3.3%) and aldehydes comprise 0.2–6.2% (av. 2.1±2.2%) of total organic carbon (TOC, 2.0–18.6 mg C l⁻¹; av. 9.8±5.4 mg C l⁻¹). Annual rain fluxes of monocarboxylic acids and aldehydes during 1982–1983 were calculated to be 0.24 and 0.11 g m⁻² yr⁻¹, respectively, with an annual estimated wet deposition in the Los Angeles Basin of 3120 and 1430 tons, respectively. These fluxes are equivalent to 2500 times of the acids and 2.5 times of the aldehydes emitted from automobile exhausts in the Los Angeles air basin. This comparison suggests that major portions of the carboxylic acids detected in the rain are not directly emitted from auto-exhausts, but are most likely produced in the atmosphere by gaseous and/or aqueous phase photo-induced reactions.     

Wet deposition of pesticides and nitrophenols at two sites in Denmark: measurements and contributions from regional sources

The concentrations of selected pesticides, of some of their degradation products and nitrophenols in rain were measured at two stations in Denmark in the period January 2000-July 2001. Forty compounds were quantified at least at one station during at least one sampling period. Additionally 17 compounds could be detected but not quantified, and 22 compounds could not be detected at all. The highest depositions of pesticides were observed for pendimethalin and desethylterbuthylazine, which is a degradation product of terbuthylazine. The deposition of the nitrophenols 2,4-dinitrophenol, DNOC, 3-methyl-4-nitrophenol was much higher than that of pesticides. The deposition of 2,4-dinitrophenol was e.g. up to a factor of 40 higher than that of pendimethalin. Atrazine, chloridazon, 2,4-D, dieldrin, disulfoton, fenitrothion, isoproturon, lenacil, metazachlor and propachlor were found in precipitation, although these pesticides are not allowed in Denmark. It can therefore be concluded that they came from abroad and have been transported over at least 60-80 km. For some of these compounds the transport distance is much longer.     

Wet deposition mercury fluxes in the Canadian sub-Arctic and southern Alberta,measured using an automated precipitation collector adapted to cold regions

This paper reports mercury (Hg) concentrations and fluxes in precipitation that was collected from 2006 to 2008 at three sites in Canada: sub-Arctic boreal forest, sub-Arctic coast, and southern Alberta, using cold-adapted precipitation collectors which operated reliably at temperatures below ?30 °C during the study. The southern Alberta site (Crossfield) may be influenced by Calgary urban air, whereas the sub-Arctic coastal (Churchill, Manitoba) and boreal forest (Fort Vermilion, Alberta) sites are in more remote northern areas. Annual mean Hg concentrations in precipitation (5.0–9.2 ng L^?1) at the study sites were in the lower half of the range reported for southern Canada and the USA by the Mercury Deposition Network (MDN). But owing to typically low precipitation rates, gross wet Hg fluxes (0.54–2.0 μg m^?2 yr^?1) were among the lowest reported by MDN, with Crossfield having about twice the flux in 2007 of the other two sites. Flux was significantly correlated with precipitation, and thus was highest in summer (June–August) and lowest during winter, a pattern typical of other temperate continental locations. There was no evidence of higher wet Hg fluxes or concentrations in springtime at Churchill where atmospheric mercury depletion events (AMDEs) occur. Measured gross deposition fluxes at the study locations were ～2–8 times lower than estimated by GEOS-Chem and GRAHM atmospheric models. The largest discrepancy occurred for Churchill, which raises the question of how well Hg deposition from AMDEs is described by current models. Better agreement between measurements and models was obtained from MDN stations in Alberta and Alaska, where wet Hg fluxes were 2–10 times higher than the study sites either because of power plant emissions (Alberta), or because of high precipitation rates (Alaska).     

Responses of soil nitrification activities to copper after a moisture stress

Environmental Science and Pollution Research - Some steps of the soil nitrogen (N) cycle are sensitive to environmental pressures like soil moisture or contamination, which are expected to evolve...     

Absorption, deposition and distribution of dietary aluminium in immature rats: effects of dietary vitamin D3 and food-borne chelating agent

We report the levels of aluminium, calcium and potassium in selected tissues of growing rats administered dietary or subcutaneous aluminium, and also the effect of dietary aluminium in combination with cholecalciferol, or with lactose plus a dietary chelating agent. Dietary aluminium decreased the growth rate of normal rats and increased the deposition of aluminium in the tissues. Animals given lactose with a dietary chelator showed a 17 - 100% increase in brain, heart, and muscle aluminium concentration in comparison with those fed aluminium alone. Animals fed both aluminium with cholecalciferol also showed increased levels (12-39%) of aluminium, chiefly in muscle and heart in comparison with those fed aluminium alone. Aluminium deposition was correlated positively with Ca2+ and K+ levels among each of these tissues. We conclude that in normal growing rats aluminium deposition is increased in heart and muscle in the presence of vitamin D3 and in brain, heart and muscle in the presence of lactose and a dietary chelating agent.     

Analyses of enzyme activities and other metabolic criteria after five years of fumigation

Enzymatic activity (peroxidase, glutamate dehydrogenase, glutamine synthetase), foliage buffering capacity, soluble protein and nitrogen content were measured in current and previous year needles from young spruce (Picea abies) and fir (Abies alba). The trees were exposed to low levels of SO(2) and/or O(3) and simulated acidic precipitation (pH 4.0) in open-top chambers from 1983 through 1988. Needle samples were taken during March 1988 at the end of the five-year fumigation period. Exposure to SO(2) substantially increased sulphur content in both needle age classes of spruce and fir, and concomitantly reduced the foliage buffering capacity index (BCI), whereas the combined fumigation with SO(2) and O(3) had no effect on BCI. Peroxidase activity was markedly higher in year-old needles compared to current-year needles. However, trees from the SO(2) and SO(2) + O(3) treatments exhibited statistically significant stimulated peroxidase activities. Similarly, changes in the activities of the nitrogen-metabolizing enzymes indicated an altered cellular function of the trees after the long-term pollution stress. Levels of activity of both glutamate dehydrogenase and glutamine synthetase were increased by exposure to SO(2), especially in spruce. Although glutamate dehydrogenase in spruce was affected by all treatments, such changes in activity were found in fir only with the SO(2) treatment. The highest activity of glutamine synthetase, however, occurred in the older needles of trees exposed to SO(2) + O(3). Total nitrogen concentration was either unaffected by the pollutant treatments or decreased in spruce compared to the controls. No statistically significant changes due to the fumigation were found in soluble protein concentrations. Results indicated that chronic exposure to air pollutants lead to alterations in metabolic processes in conifer needles, detectable either by changes in typical stress indicating values or by increases in ammonium assimilation capacity.     

Influences of the city of Bucharest on weather and climate parameters

Estimates of the urban heat island are presented based upon ground level air temperature measurement in a few representative points in Bucharest (May–December 1994). The intensity of the effect is analysed versus synoptic mesoscale patterns. Other effects of the urban area on some atmospheric parameters, particularly on cloud systems and precipitation, are presented, too, using radar images.     

Movement and deposition of two organophosphorus pesticides within a residence after interior and exterior applications

Post-application temporal and spatial distributions of two organophosphorus pesticides, diazinon (O,O-diethyl O-[6-methyl-2-(1-methylethyl)-4-pyrimidinyl] phosphorothioate, CAS No. 333-41-5) and chlorpyrifos [O,O-diethyl-O-(2-isopropyl-6-methyl-4-pyrimidinyl) phosphorothioate, CAS No. 2921-88-2], were monitored after homeowner applications for indoor and outdoor insect control. Samples of indoor air, vacuumable carpet dust, carpet dislodgeable residues, deposits on bare floors, table tops and dinnerware, surrogate food, and residues on children's hands and toys were taken before and up to 12 days after treatments in the family room, kitchen, and child's bedroom. Results from the study demonstrate the nature and magnitude of translocation of pesticides from the areas of application to surfaces accessible for human contact and permit comparisons of potential exposures via respiration and dermal contact/oral ingestion. Potential indoor inhalation exposures were estimated to be as high as 0.5 microg/kg/day for diazinon applied indoors and 0.05 microg/kg/day for chlorpyrifos applied to the outside perimeter of the house. While ingestion of carpet dust at the rate of 100 microg/day would have added a maximum of only approximately 0.01 microg/kg/day to the daily dose, residues found on the children's hands suggest that repeated mouthing could have contributed as much as 1-1.5 microg/kg/day. These estimates are below the U.S. Environmental Protection Agency (EPA) reference dose for chlorpyrifos, but exceed those for diazinon.     

Dry deposition of ozone on building materials. Chamber measurements and modelling of the time-dependent deposition

Tests of the dry deposition of ozone to the surfaces of a concrete floor tile and an activated carbon cloth (ACC) sample were performed in a deposition chamber. The time-dependent deposition of ozone to the material surfaces was modelled with an adsorption, desorption, reaction model. This made it possible to find deposition velocities at equilibrium, at t=∞, from shorter time runs of 48 h. The total equilibrium deposition velocity on the concrete floor tile was found to decrease from 0.08(10) to 0.057(10) cm s⁻¹ in three consecutive runs on the same sample, and was found to be 0.137(8) cm s⁻¹ on an ACC. All at a linear airflow velocity of 0.092 cm s⁻¹, RH=50% and T=22°C. Varying the airflow in the deposition chamber, the surface deposition velocity was found to equal to the total deposition velocity for the concrete floor tile. A surface deposition velocity of 0.186(8) cm s⁻¹ was found for the ACC sample. The total real area and the reaction rate constant for the decomposition of ozone was found to be larger, and the adsorption rate constant, the desorption rate constant and the mass of ozone on the surface smaller, on the ACC sample than on the concrete floor tile.     

Information Required for the Selection and Performance Evaluation of Wet Scrubbers

The term “wet scrubber” or simply “scrubber,” for the purpose of this report, is intended to include any device using liquid to effect the removal of solid or liquid particles which are entrained in process air or gas streams. This guide is intended to provide information required for the selection and performance evaluation of all types of scrubbers installed for the primary purpose of removing such particulates from any process gas stream. It is not intended to cover scrubbers for the collection of gaseous and/or vapor constituents which involve gas absorption mechanisms.     

高浓度脱浆污水的湿式氧化法处理研究

介绍了采用湿式空气氧化法（ＷＡＯ）对来自香港两个纺织工厂的脱浆污水进行处理的效果。所用装置为１台２Ｌ的高温高压釜。操作工况为：温度１５０￣２９０℃，氧分压０．３７５￣２．２５ＭＰａ。在每个试验的不同过程中监测了ｐＨ值、ＣＯＤ、ＴＯＣ的变化，以评估各个过程的转化效果。还研究了温度、氧分压及反应时间对处理效果的影响。对生化性很差的化学纤维脱浆污水，其ＣＯＤ、ＴＯＣ去除率分别达到９０％和８０％。