Seasonal Variations In Concentrations Research Articles

Formiate and acetate in wet deposition at Pallanza (NW Italy) in relation to major ion concentrations

Weekly samples of wet deposition were collected at Pallanza (NW Italy) from January 1987 to December 1988. Their chemistry is characterized by high mineral acidity, with a median pH value of 4.26; only in 2 out of 62 samples was pH higher than 6.0. Sulphate, nitrate and ammonium are the main ions. Formiate and acetate showed a volume weighted average of 7 and 4 μeq L−1, respectively; the values for the dissociated forms are 5 and 1 μeq L−1, respectively. The contribution of formiate and acetate (dissociated form) to the total ionic concentration is about 2%, while the contribution to free hydrogenion is about 13%, mainly deriving from formic acid. Seasonal variations in concentration and the relationships between organic acid and other ions indicate that the photolysis of isoprenoid compounds released into the atmosphere from vegetation is a significant source for formic acid. In the case of acetic acid there is a contribution from anthropogenic emissions, more marked during the winter period.

Organic acids in precipitation in the Basque country (North of Spain)

This paper discusses the results of the measurement of organic anions in precipitation collected since July 1989 in Olaeta, a rural village in the Basque Country (North of Spain). In order to gain a deeper knowledge of the characteristics and acids responsible for the free acidity observed in precipitation, a study was started within the EPOCA programme (Estudios en el Pirineo Occidental de la Contaminación Acida), for measuring organic anions: formiate, acetate and propionate. These results show that it was possible to observe organic anions in nearly every event, with a 5% contribution to the anionic total, and with an appreciable seasonal variation in concentration. The maximum contribution of organic acids to free acidity (H +) is 6% in rain events with pH≤5.0. There is significant correlation between acetic acid and inorganic ions of marine origin Cl −, Na + and Mg 2+ which might indicate the importance which the air masses of marine origin are going to have in the concentration of this acid. There is also significant correlation between formic acid and SO 4 2− and H + ions which might indicate the relatively importance contribution of formic acid to free acidity.

Seasonal variation of coumarin and flavonoid concentrations in persistent leaves of wyoming big sagebrush ( Artemisia tridentata ssp. wyomingensis: Asteraceae)

Phenolic substances present in persisent leaves of 10 wyoming big sagebrush plants ( Artemisia tridentata Nutall ssp. wyomingensis Beetle & Young; Asteracae), growing wild from an unknown seed source were monitored over a two-year period to determine intraplant, interplant and seasonal variations in concentration using high performance liquid chromatography (HPLC). Phenolics in extracts of whole flowers were also monitored from early development to senescence during year two. Up to 36 compounds were separated in the extracts and the identified constituents included a large array of coumarins and flavonoids. Statistical analyses of the data indicated that 53% of the individual phenolics present in persistent leaves varied significantly over two years at P ≥ 0.05. However, during the four-month period of flower development, concentrations of only 39% of the phenolics varied significantly in persistent leaves. A posteriori tests performed on the 11 most highly variable phenolics over the two years showed that the variation in concentration occurs between seasons and not within. The results also revealed that intraplant variability was lower than interplant variation, and interplant variability in concentrations was generally equal to seasonal variability over two years. Thus, the observed seasonable changes of phenolic concentrations in persistent leaves were found to be relatively consistent and predictable both from season to season and from year to year.

Atmospheric dustfall deposits in Varanasi City

Monthly variations in dustfall concentration was studied in the city of Varanasi, India, during 1988. For dustfall samples collection, special dustfall jars were set up at three different sites at a height of approximately 20 m above the ground in and outside the city. Collected dust deposits were chemically analysed and the results are briefly discussed. A comparison was made between these sites and concluded that the maximum concentration was found at Parav and the minimum at Banaras Hindu University. In addition, water soluble and water insoluble fractions were detected in dust deposits. A seasonal variation in concentrations was also observed.

Estimation of inorganic particulate matter in the atmosphere of Isa Town, Bahrain, by dry deposition

Inorganic particulate matter was sampled weekly during the period April 1985–April 1986 in Isa Town, Bahrain. The mean annual conductivity of water-soluble inorganic particulate matter was 59.99 μScm −1; pH 7.5; total suspended solid 0.06 gdm −3; total dissolved solid 63.79 ppm; total hardness as MgCO 3 86.80 ppm; as CaCO 3 208.05 ppm; Cl − 111.27 ppm; Na + 2.18 ppm; and NO 3 − 0.006 M. Each shows seasonal variations in concentration. The average aerosols maxima were recorded in summer. The total suspended solid (TSS) mode of aerosol displays some change, with a mean in winter of 0.039 gdm −3 and a mean value in summer of 0.044 gdm −3. The aerosols data were influenced differently by some atmospheric parameters such as temperature, humidity, wind speed and direction.

Strong similarities in seasonal concentration ratios of SO42-, NO3- and NH4+ in precipitation between Sweden and the northeastern US*

We analyzed 21-year long records of precipitation chemistry from central Scandinavia and the north-eastern US to compare seasonal variations of three major pollutant ions, SO 4 2- , NO 3 - and NH 4 + . Seasonal variations in concentrations of the individual ions were distinctly different between the two regions. However, despite these differences, we found strong and unexpected similarities between the two regions in seasonal variations of the concentration ratios NO 3 - /SO 4 2- , NH 4 + /NO 3 - and NH 4 + /SO 4 2- . A preliminary analysis suggests that these similarities are due to similarities between the two regions in chemical transformation and removal processes affecting SO 4 2- and NO 3 − in the atmosphere, and to a coupling between NH 4 + and SO 4 2- aerosol in long-range transport. Ion ratios appear to be less sensitive to seasonal variations in SO 2 and NO x emissions compared to individual ion concentrations. DOI: 10.1034/j.1600-0889.1990.t01-4-00005.x

Seasonal variation in concentration of cadmium in litter arthropods from a metal contaminated site

Seasonal variation in concentration of cadmium in litter arthropods from a metal contaminated site

Strong similarities in seasonal concentration ratios of SO<sub>4</sub><sup>2-</sup>, NO<sub>3</sub><sup>-</sup> and NH<sub>4</sub><sup>+</sup> in precipitation between Sweden and the northeastern US*

We analyzed 21-year long records of precipitation chemistry from central Scandinavia and the north-eastern US to compare seasonal variations of three major pollutant ions, SO 4 2- , NO 3 - and NH 4 + . Seasonal variations in concentrations of the individual ions were distinctly different between the two regions. However, despite these differences, we found strong and unexpected similarities between the two regions in seasonal variations of the concentration ratios NO 3 - /SO 4 2- , NH 4 + /NO 3 - and NH 4 + /SO 4 2- . A preliminary analysis suggests that these similarities are due to similarities between the two regions in chemical transformation and removal processes affecting SO 4 2- and NO 3 − in the atmosphere, and to a coupling between NH 4 + and SO 4 2- aerosol in long-range transport. Ion ratios appear to be less sensitive to seasonal variations in SO 2 and NO x emissions compared to individual ion concentrations. DOI: 10.1034/j.1600-0889.1990.t01-4-00005.x

Measurement of tire tread in urban air by pyrolysis-gas chromatography with flame photometric detection

The concentration of tire tread in suspended particulate matter (SPM) was measured by a new method based on benzothiazole generated by pyrolysis of vulcanization accelerator. The variation of production yields of benzothiazole was examined for 24 kinds of tire treads currently used in Japan Pyrolysis was carried out at 670°C using a Curie-point pyrolyzer. The vertical profile and diurnal pattern of tire tread were investigated with 4-h samples continuously collected for 24 h at a heavy traffic density area in Tokyo. The diurnal percentage of tire tread in SPM at the sampling site of 86 m height showed two peaks following the trend of traffic density throughout the day. The concentration of tire tread collected at the 86 m level was about 30% of that at the 0 m level during the daytime. The seasonal variation of concentration of tire tread in SPM was measured at the sampling site located 20 km SW of Tokyo. The weight percentage of tire tread in SPM varied between 1.3 and 3% in winter with NE-NW wind and varied between 0.5 and 1.5% in spring with SE-SW wind.

Monitoring of water quality: Seasonal variations of heavy metals in sediment, suspended particulate matter and tubificids of the Elbe river

Abstract Seasonal variations of the concentrations of the toxic heavy metals Hg, Cd and Pb in suspended particulate matter (SPM) and sediment in a shallow inlet of the Elbe River were caused by phytoplankton dynamics: In summer, the phytoplankton bloom caused an increase of SPM content and a higher sedimentation rate . A"dilution”; of the highly polluted SPM coming downstream by authochthonous phytoplankton led to a decrease of heavy metal concentration in SPM and sediment. After the break‐down of the phytoplankton bloom the heavy metal concentration in SPM increased again. No seasonal variations of heavy metal concentrations were found in the tissue of tubificids. They are, therefore, not reliable biomonitors of heavy metal pollution.

Meteorological analysis of long range transport of mineral aerosols over the North Pacific

Meteorological data are used to investigate the importance of source, transport, and removal factors in the temporal and areal variation of mineral dust concentrations observed in the SEAREX (Sea/Air Exchange Program) Network of aerosol sampling stations over the open Pacific Ocean. Earlier studies established that Asian desert dust is carried out over the ocean by the mid‐latitude westerlies and may be present over the entire North Pacific area. A 6‐year climatology of routine surface meteorological reports of dust in Asia is used to examine the broad maximum in mineral dust concentrations in the months February‐May observed at all the North Pacific sites. The gross features of this seasonal variation are controlled by the occurrence and areal extent of dust outbreaks. Secondary peaks in the frequency of dust storms, in October‐December, correspond to isolated peaks in the dust concentration at the sites closest to the mid‐latitudes. Isentropic trajectory analyses are presented for individual events of peak concentrations supporting earlier indications that the dust transport begins at high elevations over the arid regions and gradually subsides for those parcels which move toward the south. The average transport path for high concentration periods, obtained by superposing trajectory patterns for events over a 6‐year period, is shown to explain the latitudinal variation in the concentrations. Removal by local orographic showers at Oahu is shown to be unimportant, while removal by the intense tropical rainfall near Fanning Island is shown to be a dominant influence on the seasonal variation of concentrations there. Rainfall data at the remote Pacific sites indicate that the 1981–1986 period was generally representative, despite the strong El Niño/Southern Oscillation event which occurred in 1982–1983.

Seasonal variation of haemoglobin A1 in children with insulin-dependent diabetes mellitus.

The results of three controlled trials performed on children with insulin-dependent diabetes mellitus were examined for evidence of seasonal variation in concentrations of glycosylated haemoglobin (HbA1). All three studies showed lower levels during the summer months. Multiple regression analysis showed that the month of sampling accounted for a significant proportion of the total variance in HbA1 levels (P less than 0.001 in all three studies). We suggest that exercise, dietary changes and the frequency of minor illnesses may all contribute to this fluctuation which has important implications for the design of clinical trials in childhood diabetes.

Concentration of Aluminium inHalophila stipulacea(Forsk.) archers. and the substrate of the Antikyra Gulf, Greece

Abstract The concentrations of Aluminium in the marine phanerogam Halophila stipulacea and in the sediment, sampled at eight stations in the Gulf of Antikyra (Greece) were presented. The seasonal variation in concentrations of Al in the seagrass and in the substrate in all these stations were studied. The quantitative differences in Al between the different parts of the phanerogam, between H. stipulacea‐sediment and among the different sample stations have also been examined.

Factors that cause seasonal variations in Beryllium-7 concentrations in surface air

Seasonal variations in the concentration of 7Be in surface air appear to show the effects of at least four factors. The influences of variations both in the rate of exchange between the stratosphere and the troposphere and in the rate of vertical mixing within the troposphere are evident in concentrations at most sites in middle latitudes. Concentrations at high latitude sampling sites show the effect of seasonal variations in the transport of air masses from middle latitudes into the high latitudes. Several sites located in regions where there are strong seasonal variations in the rainfall rate show an inverse correlation between the 7Be concentrations and the rainfall rates, indicating the importance of washout of the atmospheric aerosol that carries the 7Be.

Seasonal variations in sulfate, nitrate and chloride in the greenland ice sheet: Relation to atmospheric concentrations

Samples from three snowpits near Dye 3 in South Greenland have been used to study seasonal variations in contaminant transport from the atmosphere to the Ice Sheet. The snowpits cover the years 1982–1987. The samples have been dated by comparing δ 18O values with meteorological data from Dye 3. Airborne concentrations of SO 2− 4 over the Ice Sheet have been estimated for the dates corresponding to each snowpit sample by statistically analyzing data from several air monitoring stations throughout the Arctic, and computing average values from the appropriate stations. Seasonal variations in concentrations in air, concentrations in snow, and mass-basis scavenging ratios (concentration in snow divided by concentration in air) have been identified. Results indicate that concentrations of SO 2− 4in the air show a strong peak in late February, resulting from long-range transport of mid-latitude anthropogenic emissions, while those in the snow show a broad peak in January, February and March with smaller seasonal variation overall. The smaller variation in the snow is attributed in part to the effect of riming, which results in more efficient scavenging during warm weather when airborne concentrations are low. The importance of riming is also supported by the annual cycle in scavenging ratio which peaks in mid-summer coincident with maximum temperatures. In agreement with previous estimates, dry deposition appears to account for 10–30% of the total SO 2− 4 in the snow. Concentrations of NO − 3 in the snow show a strong peak in summer; natural material from the stratosphere as well as anthropogenic emissions transported from the mid-latitudes may be responsible. Concentrations of Cl − in the snow are maximum in January, with relatively high concentrations during October through March and a smaller peak in July. The winter peak is believed to reflect long-range transport (LRT) of marine aerosol from north Atlantic storms, while the summer peak is attributed to seaspray from nearby coastal Greenland. Riming also may influence the seasonal variations in NO − 3 and Cl − in the snow.

Seasonal variation of concentrations of volatile organic compounds in selected German homes

Knowledge of the occurrence of volatile organic compounds (VOC) in indoor air has been steadily increasing during the last few years. However, information about the extent of the variation of VOC concentrations due to changing seasonal conditions has remained scarce. To fill this gap, VOC concentrations in 12 households in Berlin were followed over one year by exposing passive samplers for 26 two-week periods each. The analysis of VOC included determinations of alkanes, aromatics, halocarbons, and polar compounds. Smokers' and nonsmokers' homes in old and new buildings were chosen for the study. For each sampling period, the test families listed activities and the use of products susceptible to emit VOC. In one part of the study, VOC determinations were completed by measurements of the ventilation rate. In most of the households, the total VOC concentration level in winter was about two to three times higher than in summer. The compounds emanating from intermittent sources could in part be assigned to the activities of the occupants.

Seasonal variations in concentrations and fluxes of dissolved organic and inorganic materials in a tropical, tidally-dominated, mangrove waterway

Seasonal variations in concentrations and fluxes of dissolved organic and inorganic materials in a tropical, tidally-dominated, mangrove waterway

Total inorganic nitrate (particulate nitrate and nitric acid) in the atmosphere of Edmonton, Alberta, Canada

Nitric acid (HNO 3) and particulate nitrate (PN) were sampled daily during the period November 1982 to October 1983 in Edmonton, Alberta. The mean HNO 3 and PN concentrations were 0.30 and 1.22 μg m −3, respectively. Each showed strong seasonal variations in concentration with the highest daily HNO 3 value of 2.4 μg m −3 being recorded in July and the highest PN concentration, 8.1 μg m −3, in December. The mean annual total nitrate (TN) concentration of 1.5 μg m −3 was lower than reported for cities such as Toronto, 2.9 μg m −3, but higher than the 0.51 μg m −3 found during the summer in Calgary, Alberta. A comparison of PN and HNO 3 values with peroxyacetylnitrate (PAN) concentrations shows PAN to be the most abundant reaction product of nitrogen oxides present in the Edmonton atmosphere by a factor greater than 2.5. The fractional conversion of NO x to PN, HNO 3 and PAN for the 12 month period was 0.034.

Regional and seasonal variations in the flux of oceanic dimethylsulfide to the atmosphere

Dimethylsulfide (DMS) concentrations have been measured in over 1000 Pacific surface seawater samples during the past 4 years. The data have been tabulated to take into account both regional and seasonal variations in concentration. The area‐weighted summer and winter concentrations of DMS in the North Pacific Ocean are 2.2 and 1.3 nmol/L, respectively. Wind speed, surface seawater temperature, and DMS diffusivities are used to calculate air‐sea exchange coefficients. The area‐weighted summer and winter DMS piston velocities are 2.3 and 2.7 m/d, respectively. These exchange coefficients combined with the concentration data yield a net ocean to atmosphere DMS flux in the North Pacific Ocean of 0.12 Tmol/yr. Extrapolating this calculation by regional areas to the global ocean yields a net DMS flux of 0.50 Tmol/yr, less than earlier estimates of 1.2 Tmol/yr, but still consistent with excess sulfate deposition estimates and model studies of the marine atmospheric sulfur budget. The uncertainty in the flux estimate is roughly a factor of 2.

Ion Mass Balances and Seasonal Fluxes from Four Acidic Brownwater Streams in Nova Scotia

Precipitation and four brownwater streams in southwestern Nova Scotia were sampled for 3–5 yr. Precipitation cation chemistry was dominated by H+ (44% of cation equivalents) and Na+ (38%), while anions were dominated by Cl− (44%), SO42− (41%), and NO3− (15%); mean annual pH was 4.6, and acidity was correlated with concentrations of SO42− (r = 0.90) and NO3− (r = 0.82). Surface water chemistry was dominated by Na+ (51% of cation equivalents), Mg2+ (17%), and Ca2+ (16%), while H+ averaged only 4%; anions were dominated by Cl− (53%), organic anions (23%), and SO42− (21%); H+ was not strongly related to concentrations of other ionic constituents (the most consistent correlation was with sulfate, but this was weak and accounted for <30% of the variation). Hydrogen ion was consumed in all four watersheds by an average value of >75%. Water flow was by far the strongest determinant of annual pattern of flux of chemical constituents from the watersheds. Seasonal variations of concentration were of relatively small magnitude and had much less influence on patterns of flux.