Dichromate Digestion–Spectrophotometric Procedure for Determination of Soil Microbial Biomass Carbon in Association with Fumigation–Extraction

A dichromate digestion and spectrophotometric procedure is proposed for estimating soil microbial biomass carbon (C) in association with fumigation–extraction. The recommended procedure uses a volume (1.6 ml) of 0.5 M potassium sulfate (K₂SO₄) soil extracts and oxidant solution (dichromate–sulfuric acid, 2.4 mL), mixed with a volume (4 mL) for digestion at 140 °C for 30 min. The digested solution is then directly read for absorbance at 350 nm using a spectrophotometer, and the C in the digested soil extracts is measured against glucose standards. The K_EC (indicating the extractable part of microbial biomass C after fumigation) value is estimated as 0.33 for the proposed method. There are good correlations between soil microbial biomass C measured by the proposed method, the dichromate digestion titration, and oven oxidation by total organic C (TOC) analytical method. This method is a simple, rapid, and economical procedure associated with fumigation–extraction for biomass C analysis.     

Evaluation of Multi-Mixtures of Acids for the Sample Preparation of Organic Soil Amendments for Multi-Element Determination by ICP OES

A method for the simultaneous determination of aluminum (Al), arsenic (As), calcium (Ca), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), phosphorus (P), lead (Pb), sulfur (S), selenium (Se), vanadium (V), and zinc (Zn) in organic soil amendments using microwave-assisted acid digestion and inductively coupled plasma optical emission spectroscopy (ICP OES) is proposed. Concentrated or diluted acids mixtures (HNO₃, HF, HBF₄, and H₃BO₃) combined or not with H₂O₂ were systematically evaluated in order to achieve the best digestion procedure for masses of around 150 mg of samples. Principal component analysis (PCA) was applied in order to choose the best acid mixture for digestion (3 mL HNO₃ + 1 mL HBF₄ + 2 mL H₂O). The determined concentrations were in accordance with certified values of CRM 029 at the 95% confidence level, according to the Student-t test. This acid mixture was successfully applied for the digestion of four organic soil amendment samples (organic fertilizers, substrates, and soil conditioners) and element determination.     

Trace element loading of southern Lake Michigan by dry deposition of atmospheric aerosol

Aerosol samples and meteorological data were collected at a mid-southern Lake Michigan site (87° 00′ W, 42° 00′ N) from May through September 1977. Hi-volume samplers with cellulose fiber filters and a digital meteorological data recording system were operated on board the U.S. EPA's R/VRoger R. Simons during four intensive sampling periods. Aerosol samples were analyzed by atomic absorption spectroscopy for seventeen trace elements. A diabatic drag coefficient method was used to determine aerosol deposition velocity (v _d ) overlake. A meanv _d of 0.5 cm s^?1 was found for the 0.1v _d to a long-term climatological record, annual dry deposition loadings to the southern basin for nine elements were estimated. For four elements, Fe, Mn, Pb, and Zn, dry deposition loadings to the southern basin alone of at least 500, 30, 250, and 100 (×10³ kg yr^?1) were found. For Fe and Mn, these loadings represent about 15% of the total of all inputs to Lake Michigan. for Zn and Pb, about one-third to one-half of the annual loading from all sources is from dry deposition of atmospheric aerosol.     

Mineralization procedure for determination of copper in aerosols using photometric method based on copper-BPKQH complex

A mineralization procedure is proposed for copper aerosols in which samples are mineralized by wet-ashing with HNO3 + HCIO4 mixture. Copper content is determined by a photometric method based on formation of a complex between copper and benzyl 2-pyridyl ketone 2-quinolylhydrazone (BPKQH). The influence of pH, ethanol content, and reagent concentration is studied. Copper determination at pH = 7.3, in the range 0.05 to 3 ppm is proposed. Mineralization with HNO3 is carried out in different conditions of evaporation (with or without dryness) and manipulation. Analysis of variance by the (ANOVA) single factor method shows that digestion conditions significantly increase the variability of results. Repeatability assays suggest that nitric acid alone gives low precision. Recovery assays reveal that the HNO3 digestion process causes copper loss by volatilization. Mineralization with HNO3 + HCIO4 is optimized on the basis of the accuracy and precision obtained. The ANOVA method suggests that mineralization conditions significantly increase total variability of results and also that results of the photometric method are not significantly different from those of the AAS method. The optimum mineralization procedure gave an RSD of 0.63% and a copper recovery of 98.4%. The combined digestion and quantification method was applied to determination of copper in aerosol samples obtained during leaf spraying operations of olive trees in the field.     

Comparison of various methods for the determination of inorganic species in airborne atmospheric particulates

The performance of various filters used for determining inorganic species (heavy metals, light metals, anions and ammonium ion) in airborne particulates was comparatively assessed. Filters used in the determination of Ca²⁺, Mg²⁺, Na⁺, K⁺, Fe³⁺, Zn²⁺, Pb²⁺, Cr³⁺, Ni²⁺, V (V), Mn²⁺ and Cd²⁺ were attacked by acid extraction (glass microfibre filters, GF/A), acid extraction and microwave oven digestion (quartz filters, QM-A), and muffle furnace calcination and microwave oven digestion (Whatman-41 cellulose filters, W-41). The behaviour of the different filters tested towards aqueous extraction for the determination of anions (Cl^?, NO ₃ ^? , SO ₄ ^? , ammonium ion and light metals (Ca²⁺, Mg²⁺, Na⁺ and K⁺) was also studied and the results obtained for the light metals were compared with those provided by acid attack. All metals except vanadium were determined by ICP-AES; cadmium, lead and vanadium were analysed for by GFAAS; anions were quantified by ion chromatography (SO ₄ ^? was also measured by ICP-AES); and ammonium ion was determined by the Indophenol Blue method.     

Sur une nouvelle methode de dosage du dioxyde d'azote present dans les atmospheres polluees,derivee de la methode de Griess-Saltzmann

This paper discusses a procedure involving absorption of NO₂ on triethanolamine impregnated-papers according to a recent study of Levaggi, Siu and Feldstein. The used solid surfaces are Millipore filters, first impregnated by stirring them in a solution containing triethanolamine, glycerol and acetone before drying in an oven. Storage is made in a closed glass container. For sampling, check air flow rate to be about 30 l h^?1 through filters. The sampling time depends on the actual concentration. Samples are then analyzed in a laboratory under Saltzman's colorimetric reaction. The composition of the reagents is slightly modificated (acetic acid is replaced by phosphoric acid to obtain pH 1). Color development needs 30 min and then absorbance is compared with a standardization curve built from dilute solutions of Na NO₂. Absorption efficiencies of over 95% are attained with two impregnated filters in a filter holder and at about 301 h^?1 flow rate. Stability of filters after sampling is evaluated at 2 or 3 weeks, so it is possible to store several filters before sending them (for example by mail) to the laboratory for analysis. The stoichiometric factor depends on the weight (expressed in μg) of NO₂ collected on the filters and varies between 1.0 and 0.84. To measure NO, oxidation into NO₂ is first required, for example with an O₃ lamp.     

Chemical Analyses after Consecutive Extraction of Inorganic Components in Suspended Particulate Matter in Bilbao (Spain)

An extraction procedure for determining the most important inorganic components in urban suspended particulate mattercollected in glass fiber filters has been used by treating thewhole sample, rather than treating one filter portion for eachanalysis. Certain blank filters have been treated following theproposed extraction procedure in order to ascertain the leachingproblems derived from the use of glass fiber filters for collecting the samples. In the acid extractable fraction, the main problem was that high amounts of Zn were leached from thefilters themselves which rendered impossible measurements of this metal in the samples. Many of the water soluble componentsrendered high values in the blank filter treatment, especiallySO₄ ^2-, Cl^-, Ca²⁺ and Na⁺. Consequently,the sample measurements have been carried out using, as blankreference, the external crowns of the filters used for collecting the samples. The extraction procedure has been validated by using one certified material.     

Characterization of Atmospheric Aerosol in the Northern Foot of Mt. Fuji, Central Japan

The unique characteristics of atmospheric aerosol in the northern foot of Mt. Fuji, central Japan were first clarified. The Mt. Fuji (an altitute of 3776 m) is the largest basaltic stratovolcano in the quaternary period in Japan. The aerosol measurements were carried out at an altitute of 1100 m from June 2000 to April 2001. Ambient aerosol in the predominant area of a typical volcanic rock like basalt was referred to as a basaltic aerosol in this study. Fifteen elements (Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Ba, Pb) of major to trace in the aerosol samples were determined by X-ray fluorescence spectrometry. Total mass concentration (< 10 μm) of the basaltic aerosol showed the higher values in summer and spring rather than autumn to winter, and the seasonal variation pattern differed widely from that of general urban aerosol. The behavior of the basaltic aerosol was mainly controlled by mineral particles throughout the year, so that a typical anthropogenic-derived element like Pb was very rarely detected. Even V, Cr and Zn which have been generally considered to be typical anthropogenic-derived elements, showed crustal-like behaviors. A concentration ratio of Si/Al showed markedly a uniqueness of the basaltic aerosol. From a comparison with atmospheric aerosol Si/Al ratio in granitic region being an exact opposite geology, a correlation plot of Si/Al ratio against Si concentration was made. It showed a big regional difference available for source identification of atmospheric soil particles. The chemical and geological characteristics of the basaltic aerosol are very useful for the novel characterization of atmospheric soil particles.     

Atmospheric pollution in Venice,Italy, as indicated by isotopic analyses

Rainwater samples collected in Venice over a period of about 1 yr were studied along with stone samples collected from buildings and monuments. Isotopic measurements of O, S, and C were carried out on rainwater, rainwater dissolved sulfate, carbonate in stone, and sulfate present in altered limestone, with the purpose of proving that atmospheric pollution is mainly responsible for the deterioration of monuments and buildings. The results obtained lead to the conclusion that, in spite of the geographic position of the city, atmospheric sulfate in Venice is basically tied to the emission of anthropogenic SO₂ and that only minor contribution can be expected from seawater spray and aerosols. The measurements carried out on stone samples clearly indicate that stonework is damaged by the interaction between limestone and S-bearing atmospheric pollutants.     

An application of ranked set sampling for mean and median estimation using USDA crop production data

Ranked set sampling (RSS) is a sampling approach that leads to improved statistical inference in situations where the units to be sampled can be ranked (either through some subjective judgment or via the use of an auxiliary variable) relative to each other prior to formal measurement. It has the most promise for leading to improved methodology in situations where ranking of the items to be sampled can be carried out relatively easily and cheaply compared to the effort and expense required for actual quantification of the characteristic of interest. Although the theoretical benefits of RSS in estimation and statistical inference have been extensively demonstrated in the literature, the methodology has not yet been widely adopted by practitioners. The aim of this study is to use a crop production dataset from the United States Department of Agriculture to demonstrate the practical benefits of RSS relative to the more commonly used simple random sampling in estimation of the mean and median of a population. The results of our study provide clear evidence that the use of RSS can lead to substantial gains in precision of estimation for both of these situations.     

Observations on Gaseous and Aerosols Components of the Atmosphere and Their Relationships

Measurements of sulphur dioxide, ozone, ammonia, and soluble inorganic components of the atmospheric aerosol were made at a site in central southern England. Ammonia, ozone, and nitrate aerosol in winter were shown to exhibit significant diurnal variation. Ozone showed a typical diurnal variability, the magnitude of which was dependent upon wind speed. The lower night-time ozone concentrations at lower wind speeds were attributed to depletion inside nocturnal boundary layers by dry deposition. Ammonia, in contrast, showed a different behaviour, whereby the diurnal cycle was more pronounced at higher wind speeds, indicating that the cycle was unlikely to be the result of dry deposition at night. Ammonia concentrations showed a temperature dependence and the diurnal cycle of ammonia at this site appears to be the result of a temperature-driven emission signal. Of the total reduced nitrogen, NH_x (NH_x = NH₃ + NH₄ ⁺ aerosol), the phase was dominant and it is likely that more than 60% of the boundary layer NH_x is in this phase. The loss term of ammonia by reaction with acid sulphate aerosol is likely to be greater than that by dry deposition on a UK scale. Nitrate aerosol showed a positive correlation with sodium aerosol, once the effect of mutual correlations with sulphate and ammonium were removed. This correlation effect, in combination with evidence of a marine-oriented directional dependence of nitrate aerosol, and negative non sea-salt chloride aerosol from the same ‘marine’ sector, shows the potential importance of the formation of sodium nitrate aerosol from reaction of dinitrogen pentoxide, or possibly nitric acid or nitrogen dioxide with sodium chloride aerosol. It is likely that this provides the major route of nitrate into rain, not the scavenging of nitric acid vapour. Aerosol sulphate, nitrate, and ammonium have been measured at Harwell since 1954. Sulphate aerosol increased up until 1976 and has declined subsequently. Nitrate aerosol has increased over the whole period, whereas ammonium aerosol follows a similar pattern to that of sulphate, but with an equivocal direction of trend after 1976. Sulphate, nitrate and ammonium aerosol all show a similar statistically significant seasonality. A historical inventory of ammonia emissions shows a clear correlation with ammonium aerosol.     

Comparison of New Ultrasonic Digestion Approaches for Plant Matrices in the Analysis of Trace Metals by Inductively Coupled Plasma–Optical Emission Spectroscopy Analysis: Contrast with USEPA Method 3050B

An ultrasonic method using two approaches, A and B, along with a reference Environmental Protection Agency (EPA) Method 3050B [i.e., a mixture of 30 mL of nitric acid–hydrochloric acid–hydrogen peroxide–water (HNO₃-HCl-H₂O₂-H₂O)] were contrasted for leaching of a plant matrix. The trace metals were arsenic, cadmium, cobalt, chromium, copper, mercury, manganese, nickel, lead, selenium, and zinc (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Se and Zn) and quantified by ICP-OES followed by an investigation into residue formation and the impact of digestion time. Approach B was the most accurate and precise with percent recoveries ranging between 99 and 120%, whereas ultrasonic approach A and the USEPA method 3050B gave similar results with poor accuracies and precisions. In the optimization of the digestion time using approach B, the total metal recovery was fairly the same over a period of 120 min except for Cr and Cu, which showed slight variations.     

Aluminium contamination of acid soil solution isolated by means of porcelain suction cups: a reply to a paper by Hughes & Reynolds (1990) and an interpretation of aluminium release

Possible aluminium contamination of acid soil solutions isolated by use of porous porcelain suction cups (‘P.80 type’) was reported by Raulund-Rasmussen (1989). The aluminium release was explained by a proton-induced dissolution of cup material. Hughes & Reynolds (1990) suggested that the aluminium release and proton consumption could be explained by an ion-exchange reaction. In an attempt to understand the mechanism and thereby also the usefulness of suction cups, laboratory experiments were carried out to define mineralogical and chemical composition, stability under acid conditions, cation exchange capacity, and reactivity under conditions relevant to the field. The cups consisted of mullite and corundum (65% Al₂O₃) as shown by X-ray diffraction analysis. The cation exchange capacity of the cups was too low (0.65 μmol_c per cup) to explain the observed contamination of isolated soil solution. Ground cup material dissolved slowly in acid. Investigations on whole cups showed that aluminium release to acid test solutions depended on the time of exposure. It is concluded that porcelain suction cups may lead to contamination of isolated soil solution depending on: (i) the intake rate, (ii) the rinsing procedure before sampling, and (iii) the composition of the soil solution (pH and aluminium ion activity being important parameters).     

Atmospheric SO2 Pollution and Acidity of Rain in Changchun China

It is mainly SO₂ that bring about acid rain in China. Changchun City, which is located in Northeast China, is a typical city that is polluted by SO₂ from coal combustion in winter. In winter, the daily mean concentration of atmospheric SO₂ is about 0.10mg/m³ and about 5 times as high as in summer, and the daily highest concentration usually appears in daybreak and nightfall. The monitored lowest pH value of rainwater was 4.8 in spring and the range of pH value of rain/snow was 5.2–6.0 in winter, 4.8–5.8 in spring, 5.4–6.4 in summer, 5.6–6.4 in autumn, and the annual mean pH value of rainfalls was 5.8 (1999–2000). Because the alkaline aerosol from soil, meteorological conditions etc., is unfavorable to acid rain formation, even though high SO₂ emission intensity existed in winter, the acid rain did not appear obviously. The aerosol character, climate conditions in Northeast China are important factors for the acid rain formation, although SO₂ emission is the original cause.     

Anaerobic Digestion of Olive Oil Mill Effluents: Evaluation of Wastewater Organic Load and Phytotoxicity Reduction

Olive oil mill effluents (OME) are of great concern worldwide dueto their role as pollutants. This work studies, on a laboratoryscale, the possibility of reducing the polluting load of olivewastewaters (organic, acid and polyphenolic) through chemical-physical processes (sedimentation-filtration) followedby a biological treatment (anaerobic digestion). This is in orderto produce biogas and obtain an effluent suitable for applicationto the soil. The anaerobic process was followed by determiningchemical-physical parameters (pH, COD, N-NH₃, polyphenols).The extent of anaerobic digestion was evaluated throughmeasurements of biogas and volatile fatty acids and the microbialmetabolism was examined through dehydrogenase activity. Finally,tests of plant germination and growth were carried out usingdigested waters to determine if they could be used in agriculture.The study demonstrated that anaerobic digestion of OME firstreduced the organic load by 78-89% and the content of polyphenolsby 33-43%, and secondly produced biogas (mean value of methane83-85%). Phytotoxicity tests carried out on Lepidiumsativum seeds showed that the anaerobic treatment considerablyreduced the phyto-toxic character of OME.     

Deposition of acidic species at a rural location in New South Wales,Australia

Wet-only rainwater composition on a daily basis, and atmospheric SO₂ and NO₂ concentrations on a monthly basis have been measured over a two year period at four sites ～100 km to the west of Sydney. Bulk aerosol composition on a monthly basis was also measured at one site. The study region is predominantly rural in character, but contains two coal-fired thermal power stations with a total installed capacity of 2320 MW, as well as several min or population centres, including a small city, with a total population of about 21,000. The measurement sites were located roughly on the perimeter of a circle of about 20 km radius having the power stations at its centre. Three of the sites were situated in rural settings, while the fourth was located on the outskirts of the small city of Lithgow. Atmospheric acid loadings at all sites were low by the standards usually associated with industrialised regions of Europe and North America, with about one third of rainwater total acidity provided by organic acids (formic, acetic and oxalic). At the three rural sites, total inorganic acid deposition, comprising measured wet deposition plus inferred dry deposition of acidic S and N species, averaged about 30 meq m^?2 y^?1, a low figure by most standards. At the site located near the city of Lithgow total deposition of acidic S and N species averaged about 80 meq m^?2 y^?1.     

A Study on Rain Acidification Processes in Ten Cities of China

A physico-chemical sub-cloud rain acidification model is used to simulate the acidification processes of rainwater in ten cities of China, based on the observation data of the chemical components of cloud- and rainwater and the concentrations of gaseous and aerosol species. The results show that there are in-cloud process and below-cloud process in the formation of acid rain, but the relative importance of these two processes is different in various cities. The acidification of rainwater under cloud is very important in Guiyang, Shanghai, Jilin, Beijing, Changsha and Chongqing, and the in-cloud and below-cloud process contribute equally to the acidification in Guilin, however, the acidification of rainwater in cloud is more important in Nanchang and Guangzhou. Overall, the aerosol has an alkalization effect on the rain, about 11%–25% of H⁺ concentration in the rainwater is neutralized over Southern China and 60%–70% is neutralied over Northern China by aerosol species. The effect of atmospheric SO₂ on acidification of rainwater is nonlinear and is different in various regions. The effects of the variation of atmospheric NH₃, H₂O₂ and aerosol species on pH of rainwater are also discussed in detail.     

Towards a Science-Based Integrated Ozone-Fine Particle Control Strategy

Epidemiology studies relating health effects to ambient levels of ozone and fine particles have led to the modification of standards in the United States for these pollutants (substitution of an 8-h standard for ozone at 80 ppbv, and addition of 24-h and annual standards for fine particles). The interrelationships of these pollutants in the atmosphere suggest the need for an integrated, science-based strategy for their control. Secondary ozone formation has been controlled through emission controls on VOC and NO_x precursors. Fine particles are secondary products largely resulting from the oxidation of precursors (SO₂, NO_x, and VOCs). The key intermediates in both types of secondary process are free radical species and the photochemically labile compounds that produce them in the atmosphere. However, due to the complex and nonlinear nature of the processes, reductions in precursors may lead to unexpected changes in ozone and fine particle formation rates. For example, reduction in NO_x emissions may reduce ozone and nitric acid levels, but lead also to increased rates of sulfate formation in clouds and increased ammonia availability for neutralization of acidic sulfate aerosols. Reductions of SO₂ may reduce aerosol sulfate levels in the summer, but have no effect in other seasons. Reductions in VOCs may reduce ozone levels in urban core areas, but not elsewhere. An integrated, regionally and seasonally specific, emission reduction strategy is needed to cost-effectively reduce both ozone and fine particle levels.     

A chemometric approach to the comparison of different sample treatments for metals determination by atomic absorption spectroscopy in aceto Balsamico tradizionale di Modena

A comparison of different digestion procedures has been carried out for the analysis of metal concentration in samples of vinegars and Aceto Balsamico Tradizionale of Modena (ABTM) coming from an unique barrel set. In particular, classical wet, dry ashing, and closed vessel microwave digestion procedure have been utilized and compared for each investigated species. In a few cases, direct metal determination on ABTM (without treatment procedure) is proposed as possible alternative to sample manipulation. Flame atomic absorption spectrometry was used for the quantification of iron and zinc, while graphite furnace atomic absorption spectrometry was used for all the other elements (i.e., chromium, manganese, cobalt, nickel, copper, cadmium, and lead). The comparison among the different sample treatments was carried out by the use of statistical and chemometric tools. In particular, principal component analysis and ANOVA approaches were used to discriminate between the diverse analytical methods. Furthermore, for all the dissolving techniques, the analytical metal recovery was always evaluated by the application of the recovery function on the same sample matrix. In general, the recoveries were fairly good, ranging from 90 to 103%, except for Cd and Pb with dry ashing, which showed recovery values close to 55% and 67%, respectively. As regards the metals concentration of the investigated samples, the experimental data reveal for some species the presence of concentration slightly over the legal limit fixed for wine and wine vinegar.