Studies of Wet Deposition and Dustfall at Pune, India

Rain water and dustfall deposition samples were collected at Pune, an urban site (1992–98) and at Sinhagad, a rural site (1992–94). The samples were collected with wet-only and bulk collectors at Pune and with bulk collector at Sinhagad. The samples were analyzed for major ions, pH and conductivity. The study showed that the rain water at both places is alkaline (pH > 5.6). The average pH at Pune was 6.1. Neutralising components, indicated by Ca and non sea salt (nss) Mg have higher concentrations than the acidifying components SO₄ and NO₃. The wet deposition fluxes of all the ionic components were higher than the dustfall fluxes. Relative contribution from dustfall was largest for K, Ca, Mg and NO₃. Dustfall was greater at Pune, compared to Sinhagad for all components and up to double for Ca.     

A field evaluation of the Hasl wet-dry deposition collector

Samples of precipitation, dry deposition and total deposition have been obtained from Tutuila Island, American Samoa, since April 1976. These collections are part of a study of global levels of pollutants. The volume of rain water collected by a HASL wet/dry collector has averaged within 4% of the volume expected based on data obtained using a standard rain gauge. The deposition of Cl^?, SO ₄ ^?2 , NA⁺. Mg^?2 and K⁺ in the total collector, which is exposed continuously to the atmosphere, is about 10% greater than the deposition in the wet plus dry sides of the HASL collector.     

Dissolved organic carbon in soil solutions: a comparison of collection methods

A field study was undertaken to compare dissolved organic carbon (DOC) concentrations in soil solutions obtained with three different sampling methods over a range of soil types. The sampling devices used were a tension‐free collector, a tension Prenart collector and a tension Rhizon collector. Samples were collected fortnightly for a year at seven sites in northern England, each collection being replicated three times. The soil solution DOC ranged from 1.3 g m^?3 in an acid ranker to 34.7 g m^?3 in a peat. The DOC concentrations obtained with the three methods correlated reasonably well (r² = 0.6–0.8) but with an indication of bias, as the best fit line differed from the 1:1 line. The tension‐free collector gave generally higher DOC concentrations except at very low concentrations (in the acid ranker soil). The DOC concentrations measured with the tension‐free collectors were significantly (P < 0.05) higher than those obtained with Prenart and Rhizon collectors at four and six sites, out of seven, respectively. Subsequent laboratory tests on tension‐free collected samples showed no DOC loss on filtration through 0.1 and 0.22‐μm membranes, whereas a significant loss of DOC occurred when tension‐free collected samples were subsequently passed through Prenart and Rhizon collectors, indicating a probable sampling artefact with the tension devices. The difficulties of acquiring representative soil solution samples are discussed, together with the advantages and disadvantages of tension and tension‐free methods.     

Precipitation chemistry at sinhagad-a hill station in India

The chemistry of precipitation in remote sites such as mountain tops is of interest in the study of atmospheric pollution and acid rain. The chemical composition measured at mountain site which is away from industrial and urban areas is useful as a reference level and it allows to determine the extent of anthropogenic contamination. Hence, rain water samples were collected at Sinhagad (18°21N, 73°45E, 1450 m asl during the monsoon season (June-September) of 1992 and were analysed for major ions. The precipitation samples collected at Sinhagad were alkaline in nature and pH values ranged between 5.9 to 6.76. The ionic composition was dominated by soil dust The concentration of Ca²⁺ was highest among all the ions. The concentrations of excess SO₃ ^2– and NO₄ ^– were small (23.8 and 15.2 eq l^–1 respectively) compared to the values of polluted regions in India. The correlation coefficient between the ions and pH values was calculated and it was found to be maximum in case of Ca²⁺. Precipitation samples collected at Sinhagad were alkaline owing to higher concentration of Ca²⁺ and lower levels of acidic pollutants (SO₄ ^2– and NO₃ ^–).     

Determination of strontium isotope ratio of brown rice for estimating its provenance

The strontium isotope ratio (⁸⁷Sr / ⁸⁶Sr) of brown rice (Oryza sativa L.) was determined by multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) in order to evaluate the values of ⁸⁷Sr / ⁸⁶Sr for use in the estimation of the area of rice production. Sample solutions were prepared from 5 g of rice samples using the acid (HNO₃-HClO₄-HF) digestion method. Removal of rubidium from the sample solutions was performed using ion-exchange resin (Dowex 50W X8). The Sr isotope ratios were determined with a precision of < 0.01% (RSD, repetitions = 60) by MC-ICP-MS. Typical analysis time for a single sample was about 15 min, reflecting the high sample throughput. The Sr isotope ratios of the Japanese rice samples ranged from 0.706 to 0.709. The Sr isotope ratios of the Chinese and Vietnamese rice samples (0.710 to 0.711) were slightly higher than those of almost all the Japanese samples. Australian rice showed the highest Sr isotope ratio (0.715 to 0.717) among all the rice samples examined. In contrast, the Sr isotope ratio of Californian rice (0.706) was lower than that of almost all the Japanese samples. The variation in the ⁸⁷Sr / ⁸⁶Sr ratios for the rice samples analyzed in this study clearly demonstrated that the Sr isotope ratios could provide a key information for the estimation of rice provenance.     

Effects of pretreatment of soil samples on N mineralization in incubation experiments

Summary We studied the effects of pretreating soil samples (field-fresh, drying at 40° and 105°C, freezing/thawing) on N mineralization in an incubation experiment and on the dynamics of the organic N fraction extracted by K₂SO₄ solution. The soil samples were collected from plots in a long-term field experiment with the application of mineral fertilizer and farmyard manure. Compared with the field-fresh soil samples, freezing/thawing resulted in higher NO ₃ ^– -N contents while the NH ₄ ⁺ -N and the organic N content were increased by drying at 105°C. During the incubation period N mineralization was highest after the samples were dried at 105°C and a little lower in those dried at 40°C. After freezing/thawing the order of magnitude of N mineralization remained the same. The difference in organic N between the beginning and the end of the incubation experiment and the mineral N content at the end of the experiment were correlated significantly. Despite this correlation, however, the change in the organic N content underestimated the N mineralization rates.     

Chemistry of Fog Water Collected in the Mt. Rokko Area (Kobe City, Japan) between April 1997 and March 2001

Fog chemistry was studied for four years (April 1997–March 2001) at Mt. Rokko (altitude 931 m) in Kobe, Japan. A collection of samples was obtained at a mountainous site close to a highly industrialized area. The samples were collected by an active string-fog collector. The summer fog was dense and frequent. The geography of Mt. Rokko is linked to the seasonality of the occurrence and the thickness of the fog. Among the meteorological parameters, the relative humidity was important for the occurrence of fog. The correlation of the concentrations of the components in fog water indicated that (NH₄)₂SO₄ and/or NH₄HSO₄ were involved in the process of the formation of fog drops in the atmosphere. The concentration of the components decreased with an increase in the liquid water content (LWC) of the fog, and the seasonal variation of the concentration of some components depended on the seasonal variation of the LWC. The equivalent ratio of NO₃ ^? to non-sea salt (nss?) SO₄ ^2? was considerably larger than that in precipitation. Ammonium ion accounted for the largest percentage of cations, which indicates that NH₄ ⁺ was an important counter cation for NO₃ ^? and nss-SO₄ ^2?. A unique fog event in which the air pollutants seemed to be scavenged stoichiometrically was sometimes observed. The methodology used for collecting fog water at 60 mL intervals provided detailed information.     

Nitrogen transformations in tropical soils under conventional and sustainable farming systems

Samples of alluvial soil from mixed sandstone shale and slate and of Taiwan clay were collected from two sites, both managed under a similar crop rotation scheme. The fields were further divided into sections which were managed under either conventional farming or sustainable farming practices. When the soil samples were collected in April 1989, after 1 year of operation under conventional or sustainable practices, the nitrification activities of both soils managed under sustainable practices practices. The nitrifying activities in Taiwan clay samples collected in April 1993 which had been managed with chemical or with organic fertilizer were not significantly different. However, nitrifying activity in the alluvial soil was higher under sustainable than under conventional practices. Numbers of NH ₄ ⁺ -oxidizing bacteria were not significantly different in any of the soil samples irrespective of the different management practices. In contrast, higher numbers of NO ₂ ^- -oxidizing bacteria were detected in both soils managed sustainably. The results also indicated that the composition of NH ₄ ⁺ -oxidizing bacteria differed in the alluvial soil when managed with different kinds of fertilizer.     

Analysis of the 1:5 soil: water extract in burnt soils to evaluate fire severity

This paper studies fire severity through changes in the composition of the 1:5 soil: water extract in burnt and unburnt samples collected after a wildfire that affected 7.1 ha of mountainous broom scrub (Teide broom, Spartocytisus supranubius L.) in Tenerife (Canary Islands). Soil samples were collected over a regular sampling grid and analysed for pH, electrical conductivity (E.C.), and soluble cations (Ca⁺², Mg⁺², K⁺, and NH₄⁺–N) and anions (P, SO₄^− 2–S, and NO₃⁻?N). A visual estimation of fire effects on individual broom plants was also conducted. The results show significant differences between burnt and unburnt samples for pH, E.C. and soluble ions (except for P), which generally agrees with data reported in the literature. Although fire severity, as estimated from the degree of fuel combustion, correlated significantly with most of the studied parameters, the qualitative fire severity indexes failed to discriminate sample groups apparently exposed to moderate fire severity conditions. Multivariate statistical analysis (PCA) allowed extracting two main factors, capable to account for 88% of total variability, after rejecting three variables (inorganic N-forms and K⁺). These factors were related to fire severity and pH-dependent Ca⁺² and P reactions, respectively.     

Elemental concentrations in fresh snowfall across a regional transect in the northeastern U.S.: Apparent sources and contribution to acidity

Fresh snowfall was collected on the surface of 8 lakes across a 350 km west-east transect from northeastern New York state to the coast of Maine after a single storm. In addition, every snowfall event during the winter of 1993 was collected on a single lake near the center of the transect. Across the transect, midwestern sources appear to dominate Pb and Cd concentrations, while Sb appears to be derived from midwestern sources as well as local and/or industrial East Coast sources. In all samples, the highest Na, Cl and Mg concentrations reflect a marine influence, but at some transect sites roadspray aerosol appears to contribute to Na and Cl concentrations. The regional pattern of Ca, K, Mn and Sr concentrations and Mn/Sr ratios indicate that woodsmoke may be an important winter source of these elements at some sites. In all samples, H⁺ is strongly correlated with NO₃ ^? (R² = 0.97) and mean NO₃ ^?/SO₄ ^2? molar ratios of 6.4 for transect samples, and 4.7 for temporal samples, are higher than mean NO₃ ^?/SO₄ ^2? reported for other precipitation studies in the same region. The contribution of NO₃ ^? to the snowpack greatly exceeds that of SO₄ ^2?, and may be a major source of acidity in aquatic ecosystems during snowmelt.     

Effects of cold storage on anion,ammonium, and total nitrogen concentrations in soil water

Abstract

Researchers frequently must store water samples >24 h after collection until chemical analyses can be accomplished. Samples are commonly stored in darkness at near‐freezing temperatures until analysis, but effects of this storage method on soil water chemistry are not well‐documented. Soil water samples were collected from eastern hemlock [Tsuga canadensis (L.) Carriere] stands and analyzed initially and over time to determine if nitrate (NC₃ ^‐), chloride (Cl^‐), sulfate (SO₄ ^2‐), ammonium (NH₄ ⁺), and/or total nitrogen (TN) concentrations changed when samples were stored in darkness at 2–4°C. Subsamples were analyzed <24 h after collection and reanalyzed five times in a 12 to 24 wk period following sample collection. Nitrate concentrations remained stable for at least one wk and were only slightly lower than initial concentrations after 3–16 wk of storage. Chloride and SO₄ ^2‐ remained stable for 16 wk, while TN remained stable for 8 wk and decreased slightly after 24 wk. Most NH₄ ⁺ concentrations were below the limit of quantification, but concentrations of samples with quantifiable NH₄ ⁺ decreased in the first week of storage. Overall, cold storage in darkness was effective for preserving NO₃ ^‐, Cl^‐, SO₄ ^2‐, and TN concentrations in soil water, but NH₄ ⁺ analyses should probably be performed as soon as possible after sample collection.     

Comparison of Long-Term Precipitation Chemistry Measurements at the Hubbard Brook Experimental Forest,New Hampshire

From 1978 through 1989, a wet-onlyprecipitation collector operated for the NationalAtmospheric Deposition Program, an independantwet-only collector, and a bulk precipitation collectorwere co-located at the Hubbard Brook ExperimentalForest (HBEF) in central New Hampshire. A secondbulk precipitation collector was maintained at anotherlocation within the HBEF. There were statisticallysignificant differences between the chemistry fromco-located wet-only collections for Ca²⁺,K⁺, NH₄ ⁺, pH, and NO₃ ^-. Thedifferences for K⁺ and pH though statisticallysignificant were very small but consistant. Thedifferences for Ca²⁺ were related to earlycontamination problems, and differences inNH₄ ⁺ and NO₃ ^- were related toepisotic events. Bulk precipitation was significantlyricher in K⁺ than wet-only precipitation. Therewere no differences for any ions between the bulkcollections at the two locations. While there wereminor differences, after 1981 when the contaminationproblems had been resolved, data from all collectorsat all locations adequately characterized theprecipitation chemistry of the site.     

The snowfall chemistry collector intercomparison test (SCCIT)

The Snowfall Chemistry Collector Intercomparison Test (SCCIT) took place as part of a field experiment of the PRocessing of Emissions by Clouds and Precipitation (PRECP) program during January and February 1986 in western New York. SCCIT compared the chemical composition and equivalent water depth of snow collected with a large, bag-lined can (used by the PRECP community for a concurrent surface snowfall network); the most widely used automatic wet/dry collector; an aerodynamically designed, heated, funnel and bottle system; and a large plastic sheet. The aerodynamically designed system had significantly higher concentrations of analytes than the other systems, particularly H⁺ and SO₄ ^2?, apparently because of evaporative losses. Samples from the bag-lined can were more acidic than those from the automatic wet/dry collector. The aerodynamically designed system and the bag-lined can indicated greater snow amounts than the other methods.     

Isotope (C and C) analysis of deep peat CO2 using a passive sampling technique

We developed and tested a new method to collect CO₂ from the surface to deep layers of a peatland for radiocarbon analysis. The method comprises two components: i) a probe equipped with a hydrophobic filter that allows entry of peat gases by diffusion, whilst simultaneously excluding water, and, ii) a cartridge containing zeolite molecular sieve that traps CO₂ passively. We field tested the method by sampling at depths of between 0.25 and 4 m at duplicate sites within a temperate raised peat bog. CO₂ was trapped at a depth-dependent rate of between ∼0.2 and 0.8 ml d⁻¹, enabling sufficient CO₂ for routine ¹⁴C analysis to be collected when left in place for several weeks. The age of peatland CO₂ increased with depth from modern to ∼170 BP for samples collected from 0.25 m, to ∼4000 BP at 4 m. The CO₂ was younger, but followed a similar trend to the age profile of bulk peat previously reported for the site (Langdon and Barber, 2005). δ¹³C values of recovered CO₂ increased with depth. CO₂ collected from the deepest sampling probes was considerably ¹³C-enriched (up to ∼+9‰) and agreed well with results reported for other peatlands where this phenomenon has been attributed to fermentation processes. CO₂ collected from plant-free static chambers at the surface of the mire was slightly ¹⁴C-enriched compared to the contemporary atmosphere, suggesting that surface CO₂ emissions were predominantly derived from carbon fixed during the post-bomb era. However, consistent trends of enriched ¹³C and depleted ¹⁴C in chamber CO₂ between autumn and winter samples were most likely explained by an increased contribution of deep peat CO₂ to the surface efflux in winter. The passive sampling technique is readily portable, easy to install and operate, causes minimal site disturbance, and can be reliably used to collect peatland CO₂ from a wide range of depths.     

Quinone profiling of bacterial populations developed in the surface layer of volcanic mudflow deposits from Mt. Pinatubo (the Philippines)

The diversity of bacterial populations developed in the surface layer (0-0.25 m depth) of volcanic mudflow deposits from the Mt. Pinatubo volcano (the Philippines) was investigated using quinone profiling. Samples were collected from sites (named N and S1) that had been hit repeatedly by mudflows during successive rainy seasons after the violent eruption of 1991 and also from sites (F1 and F3) covered by mudflow in 1991 but with no deposition in following years. The total microscopic count ranged from 10⁸ g⁻¹ (N and S1 sites) to 3.9×10⁹ g⁻¹(site F3). In the N sample only three quinone species were detected, while the quinone profiles of samples from sites S3 and F3 showed higher diversity. Tetrahydrogenated menaquinone with eight isoprenoid units [MK-8 (H₄)] was the predominant quinone species in the sample from site N, while MK-8, MK-8 (H₂), MK-8 (H₄), MK-9 (H₄) and MK-9 (H₈) were found as major quinones in the sample from site F3. Because these MK species are known to be the major respiratory quinones of the Actinobacteria, this bacterial group is expected to predominate in the land with primary vegetation recovery following the impact of the volcanic mudflow.     

Adsorption of chromium(VI) ions on Brazilian smectite: Effect of contact time,pH, concentration,and calorimetric investigation

The original smectite clay mineral has been collected from Amazon region, Brazil. The compound 2-aminomethylpyridine (AMP) was anchored onto Amazon smectite surface by heterogeneous route. The natural (SMC) and modified (SMC_AMP) smectite samples were characterized by elemental analysis, scanning electron microscopy, N₂ adsorption, X-ray diffraction, and silicon-29 and carbon-13 nuclear magnetic resonance. Due to the increment of basic centers attached to the pendant chains, the metal adsorption capability of the final chelating material, was found to be higher than the precursor. The ability of these materials to remove Cr(VI) from aqueous solution was followed by a series of adsorption isotherms at room temperature and pH 4.0. The maximum number of moles adsorbed was determined to be 1.16 and 1.87 mmol g^− 1 for SMC and SMC_AMP, respectively. In order to evaluate the clay samples as adsorbents in dynamic system, a glass column was fulfilled with clay samples (1.0 g) and it was fed with 2.0 × 10^− 4 mol dm^− 3 Cr(VI) at pH 4.0. The energetic effects caused by metal cation adsorption were determined through calorimetric titrations. Thermodynamics indicated the existence of favorable conditions for such Cr(VI)–nitrogen interactions.     

Acid deposition near a sour gas plant in southwestern Alberta

Atmospheric fallout in the vicinity of a sour gas plant in southwestern Alberta was collected on an event basis with bulk precipitation collectors during June, July and August of 1972, 1973 and 1982. Samples were collected at 9 sites within 20 km of the plant. Total atmospheric sulfation measurements defined a higher exposure area located downwind of the plant, but the precipitation measurements did not. Bulk deposition of H⁺ ion in the study area was an average 10.77 mmol H⁺ m^?2 3 mol^?1 in 1972 and 0.014 and 0.049 in 1973 and 1982, respectively. 1972 samples were also significantly more acidic (average pH of 4.3 vs 5.7 in 1973 and 5.3 in 1982). Deposition of SO₄ ⁼ averaged 2.1 kg S ha^?1 3 mol^?1 in 1972 and 0.96 and 0.72 in 1973 and 1982. The higher deposition of both S and H⁺ in 1972 is mainly a result of more precipitation. There was no significant correlation between H⁺ and SO₄ ⁼ species in the samples. There was no significant relationship between plant S emissions and deposition rates, or plant S emissions and average total atmospheric sulfation measurements.     

Influence of spatial root distribution,organic nitrogen mineralization and fertilizer application on soil interlayer ammonium

The amount of interlayer NH ₄ ⁺ -N and net mineralization of organic N were measured at periodic intervals, over a period of 10 months, in soil samples collected from a peach orchard which had been subjected to different rates of N fertilizer application. Two different groups of soil samples, designated sampling 1 and sampling 2 were collected. Soils of sampling 1 were collected from sites where the soil was heavily penetrated by tree roots and those of sampling 2 were collected from sites where the soil remained free from tree roots. In sampling 1, during the 10-month period, the concentration of interlayer NH ₄ ⁺ -N showed significant variations, while in sampling 2 no significant variation was found. In sampling 1 the amount of NH ₄ ⁺ -N released from the interlayers of the clay minerals were not influenced by the N fertilizer application rate. Changes in the interlayer NH ₄ ⁺ -N concentrations were related to variation in net N mineralization and immobilization rates as well as to plant uptake N. It is concluded that, in our experiment, the dynamics of interlayer NH ₄ ⁺ -N in soil were influenced by the spatial distribution of the tree roots and organic N mineralization, while N application influenced seasonal variation but not the total interlayer NH ₄ ⁺ -N released during the experiment.     

福建菜田氮磷积累状况及其淋失潜力研究

本文通过采集460个福建菜田代表性耕层土样,采用土壤测试和土柱渗漏水模拟试验的方法研究菜田土壤硝态氮和Olsen P含量状况和淋失临界指标及其淋失潜力。结果表明,耕层土壤硝态氮含量为47.455.5 mg/kg,Olsen-P含量则为61.743.2 mg/kg, 其中瓜果类蔬菜种植地土壤硝态氮和Olsen-P含量明显高于叶菜类和根茎类蔬菜种植地。 应用双速率转折点建模法,得到氮、 磷淋失临界指标X0分别为土壤硝态氮76.3 mg/kg和Olsen-P 42.8 mg/kg。 淋失临界值相当于或略高于满足蔬菜营养的农学指标。当土壤硝态氮或Olsen-P含量低于X0时,随着其含量增加,渗漏水硝态氮或总磷浓度以线性方式缓慢增加,反之,则以非线性形式急剧增大。土壤硝态氮和Olsen-P含量高于其X0的土样数分别占17.9%和81.3%, 表明这些样点具有较高的氮、 磷淋失潜力,是氮、 磷污染控制的关键地块。 瓜果类菜田土壤硝态氮和Olsen-P含量高于其X0的土样数分别占到32.3%和96.3%,淋失潜力明显高于叶菜类和根茎类菜田,是氮、 磷污染控制的优先区域。     

Nitrogenase activity associated with pasture grasses in Northern New South Wales

Nitrogenase activity associated with roots of grasses was initially examined at 67 sites in New South Wales using an enriched malate medium. Twenty six of the 39 grass species examined produced at least 10 nmol C₂H₄cm^?1 root h^?1—a level accepted as positive presumptive evidence of N₂-fixation: 40 of the 288 samples exceeded 100nmol C₂H₄h^?1. The seasonal N₂ase activity of up to 4 grass species collected in soil cores at 6 sites was measured over 16 months.Activity at field moisture levels, but incubated at 30°C was greatest for cores collected in summer months. Activity was increased in 33.5% of samples by raising soil moisture to field capacity. No single species of grass consistently supported higher activity than any other.Nitrogenase activity was compared in cores of Kikuyu grass (Pennisetum clandestinum) watered to in excess of field capacity and allowed to drain for between 7 and 28 days before re-watering. Activity declined rapidly in the first 7 days and although recovery was also rapid, integration of N₂ase activity over time showed a loss of 20 and 61% for 7 and 28 days drainage respectively. N₂ase activity was greatest at 30°C.Maximum N₂ase activity in field samples was only 246 nmol C₂H₄ core^?1 h^?1 indicating that fixation of N₂ would not be of agronomic significance.