A modification of Childs' field test for ferrous iron and ferric-organic complexes in soils.

Soil Research ◽  
1982 ◽  
Vol 20 (3) ◽  
pp. 261 ◽  
Author(s):  
JA Kennedy ◽  
HKJ Powell ◽  
JM White
Keyword(s):  
Field Test ◽  
Ferrous Iron ◽  
Nitrilotriacetic Acid ◽  
Water Soluble ◽  
Organic Species ◽  
Organic Complexes

A modification to Childs' field test for water-soluble and exchangeable ferrous iron in soils is described. To prevent redox decomposition of ferric-organic species, which is induced by the reagent �,�' -dipyridyl, a mixed NTA (nitrilotriacetic acid)-�,�-dipyridyl reagent at pH 7 is recommended.

Field tests for ferrous iron and ferric-organic complexes (on exchange sites or in water-soluble forms) in soils

Soil Research ◽  
1981 ◽  
Vol 19 (2) ◽  
pp. 175 ◽  
Author(s):  
CW Childs
Keyword(s):  
Soil Sample ◽  
Field Test ◽  
Ferrous Iron ◽  
Ammonium Acetate ◽  
Field Tests ◽  
Water Soluble ◽  
Organic Ligands ◽  
The Other ◽  
Positive Test ◽  
Organic Complexes

A 1 M solution of ammonium acetate containing �, �-dipyridyl indicator is recommended for use in field tests for exchangeable and water-soluble ferrous iron in soils. In using the test, a soil sample may be added to a vial containing the solution, or the solution can be sprayed on to a freshly exposed soil face. A field test for ferric-organic complexes in soils, using the same vials, is proposed. This is based on the photochemical nature of the reduction of ferric to ferrous iron in the presence of oxidizable organic ligands. Two subsamples of soil are added to separate vials, and light is excluded from one. After 5-15 min, a positive test for ferrous iron in the vial exposed to light, and a negative test in the other, indicates the presence of ferric-organic complexes.

scholarly journals Explicit modeling of volatile organic compounds partitioning in the atmospheric aqueous phase

2013 ◽  
Vol 13 (2) ◽  
pp. 1023-1037 ◽  
Author(s):  
C. Mouchel-Vallon ◽  
P. Bräuer ◽  
M. Camredon ◽  
R. Valorso ◽  
S. Madronich ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Water Content ◽  
Gas Phase ◽  
Aqueous Phase ◽  
Water Soluble ◽  
Chemical Mechanism ◽  
Organic Species ◽  
Cloud Water Content ◽  
Isoprene Oxidation

Abstract. The gas phase oxidation of organic species is a multigenerational process involving a large number of secondary compounds. Most secondary organic species are water-soluble multifunctional oxygenated molecules. The fully explicit chemical mechanism GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere) is used to describe the oxidation of organics in the gas phase and their mass transfer to the aqueous phase. The oxidation of three hydrocarbons of atmospheric interest (isoprene, octane and α-pinene) is investigated for various NOx conditions. The simulated oxidative trajectories are examined in a new two dimensional space defined by the mean oxidation state and the solubility. The amount of dissolved organic matter was found to be very low (yield less than 2% on carbon atom basis) under a water content typical of deliquescent aerosols. For cloud water content, 50% (isoprene oxidation) to 70% (octane oxidation) of the carbon atoms are found in the aqueous phase after the removal of the parent hydrocarbons for low NOx conditions. For high NOx conditions, this ratio is only 5% in the isoprene oxidation case, but remains large for α-pinene and octane oxidation cases (40% and 60%, respectively). Although the model does not yet include chemical reactions in the aqueous phase, much of this dissolved organic matter should be processed in cloud drops and modify both oxidation rates and the speciation of organic species.

scholarly journals Ion Mobility Spectrometry-Mass Spectrometry (IMS-MS) for on- and off-line analysis of atmospheric gas and aerosol species

2016 ◽  
Author(s):  
Jordan E. Krechmer ◽  
Michael Groessl ◽  
Xuan Zhang ◽  
Heikki Junninen ◽  
Paola Massoli ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Ion Mobility Spectrometry ◽  
Ion Mobility ◽  
Measurement Techniques ◽  
Molecular Ions ◽  
Molecular Structures ◽  
Water Soluble ◽  
Oxidation Products ◽  
Time Resolved ◽  
Organic Species

Abstract. Measurement techniques that provide molecular-level information are needed to elucidate the multi-phase processes that produce secondary organic aerosol (SOA) species in the atmosphere. Here we demonstrate the application of ion mobility spectrometry-mass spectrometry (IMS-MS) to the simultaneous characterization of the elemental composition and molecular structures of organic species in the gas and particulate phases. Molecular ions of gas-phase organic species are measured online with IMS-MS after ionization with a custom build nitrate chemical ionization (CI) source. This CI-IMS-MS technique is used to obtain time-resolved measurements (5 min) of highly oxidized organic molecules during the 2013 Southern Oxidant and Aerosol Study (SOAS) ambient field campaign in the forested SE US. The ambient IMS-MS signals are consistent with laboratory IMS-MS spectra obtained from single-component carboxylic acids and multicomponent mixtures of isoprene and monoterpene oxidation products. Mass-mobility correlations in the 2-dimensional IMS-MS space provide a means of identifying ions with similar molecular structures within complex mass spectra and are used to separate and identify monoterpene oxidation products in the ambient data that are produced from different chemical pathways. Water-soluble organic carbon (WSOC) constituents of fine aerosol particles that are not resolvable with standard analytical separation methods, such as liquid chromatography (LC), are shown to be separable with IMS-MS coupled to an electrospray ionization (ESI) source. The capability to use ion mobility to differentiate between isomers is demonstrated for organosulfates derived from the reactive uptake of isomers of isoprene epoxydiols (IEPOX) onto wet acidic sulfate aerosol. Controlled fragmentation of precursor ions by collisional dissociation (CID) in the transfer region between the IMS and the MS is used to validate MS peak assignments, elucidate structures of oligomers, and confirm the presence of the organosulfate functional group.

The toxicity of copper to the marine bacterium Vibrio alginolyticus

1985 ◽  
Vol 31 (1) ◽  
pp. 83-87 ◽  
Author(s):  
Donald R. Schreiber ◽  
Andrew S. Gordon ◽  
Frank, J. Millero
Keyword(s):  
Marine Bacterium ◽  
Carbon Assimilation ◽  
Nitrilotriacetic Acid ◽  
Vibrio Alginolyticus ◽  
Anaerobic Culture ◽  
Aerobic Culture ◽  
Organic Complexes ◽  
Toxic Concentration ◽  
Effect Of Copper ◽  
Aerobic And Anaerobic

The toxicity of copper to the marine bacterium Vibrio alginolyticus was examined. Experiments were conducted with both aerobic and anaerobic cultures. Calorimetric and radiochemical techniques were used to examine the effect of copper on heat production, respiration, and carbon assimilation by the cultures. Plate counts were used to determine the number of viable cells present. Copper was more toxic to the bacterium in anaerobic culture (mean toxic concentration (TC50) = 2.1 μM)) than in aerobic culture (TC50 = 6.4 μM). Both cytotoxic and cytostatic effects were observed. The cytotoxic effect was not significantly different under aerobic and anaerobic conditions. The cytostatic effect, observed only in anaerobic culture, resulted in a decrease in the rate of metabolism of the surviving cells. The magnitude of the cytostatic and cytotoxic effects were dependent on the copper concentration, exhibiting saturation at higher concentrations. Organic chelators EDTA and nitrilotriacetic acid protected the anaerobic cultures from the copper, indicating that Cu–organic complexes are not toxic to the organism.

Oxalate Determination: Analytical Problems Encountered with Certain Plant Species

1968 ◽  
Vol 51 (5) ◽  
pp. 963-967 ◽  
Author(s):  
R H Abaza ◽  
J T Blake ◽  
E J Fisher
Keyword(s):  
Atomic Absorption ◽  
Ferrous Iron ◽  
Complete Removal ◽  
Atomic Absorption Spectrophotometry ◽  
Water Soluble ◽  
Absorption Spectrophotometry ◽  
Oxidation Reduction ◽  
Brownish Black ◽  
Magnesium Salts

Abstract Accurate quantitative determination of oxalate in chemical analyses of edible plants is important because oxalate is a poisonous compound. The traditional KMn04-oxalate reduction-oxidation (Dye) method of analyzing for plant oxalate content presents two problems: (a) Plant pectins are not entirely separated in the determination of watersoluble oxalate and interfere in the oxidation of oxalate; and (b) a brownish-black precipitate containing ferrous iron is precipitated at the same pH as calcium oxalate and the precipitate interferes in determination of both water- and acid-soluble oxalate. Our modification of the Dye method consists of (a) using double-distilled water as the diluting medium, (6) increasing the acidity of the water-soluble oxalate medium after plant digestion to obtain complete removal of pectins, and (c) eliminating the ferrous iron-containing precipitate by filtration. Oxalate in the ferrous iron-containing precipitate is determined as calcium and magnesium salts by atomic absorption spectrophotometry; the value thus obtained is added to the oxalate value from the oxidation- reduction method. An indirect analytic method for oxalate, in which all of the oxalate was precipitated as the calcium salt and then measured by atomic absorption spectrophotometry, proved to be inaccurate

scholarly journals Cloud droplet activation of black carbon particles coated with organic compounds of varying solubility

2018 ◽  
Vol 18 (16) ◽  
pp. 12477-12489 ◽  
Author(s):  
Maryam Dalirian ◽  
Arttu Ylisirniö ◽  
Angela Buchholz ◽  
Daniel Schlesinger ◽  
Johan Ström ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Black Carbon ◽  
Glutaric Acid ◽  
Theoretical Calculations ◽  
Water Soluble ◽  
Climate Effect ◽  
Organic Species ◽  
Surprising Effect ◽  
Study Laboratory ◽  
Ccn Activity

Abstract. Atmospheric black carbon (BC) particles are a concern due to their impact on air quality and climate. Their net climate effect is, however, still uncertain. This uncertainty is partly related to the contribution of coated BC particles to the global cloud condensation nuclei (CCN) budgets. In this study, laboratory measurements were performed to investigate CCN activity of BC (REGAL 400R pigment black) particles, in pure state or coated through evaporating and subsequent condensation of glutaric acid, levoglucosan (both water-soluble organics) or oleic acid (an organic compound with low solubility). A combination of soot particle aerosol mass spectrometer (SP-AMS) measurements and size distribution measurements with a scanning mobility particle sizer (SMPS) showed that the studied BC particles were nearly spherical agglomerates with a fractal dimension of 2.79 and that they were coated evenly by the organic species. The CCN activity of BC particles increased after coating with all the studied compounds and was governed by the fraction of organic material. The CCN activation of the BC particles coated by glutaric acid and levoglucosan were in good agreement with the theoretical calculations using the shell-and-core model, which is based on a combination of the CCN activities of the pure compounds. The oleic acid coating enhanced the CCN activity of the BC particles, even though the pure oleic acid particles were CCN inactive. The surprising effect of oleic acid might be related to the arrangement of the oleic acid molecules on the surface of the BC cores or other surface phenomena facilitating water condensation onto the coated particles. Our results show that present theories have potential for accurately predicting the CCN activity of atmospheric BC coated with organic species, given that the identities and amounts of the coating species are known. Furthermore, our results suggest that even relatively thin soluble coatings (around 2 nm for the compounds studied here) are enough to make the insoluble BC particles CCN active at typical atmospheric supersaturations and thus be efficiently taken up by cloud droplets. This highlights the need for an accurate description of the composition of atmospheric particles containing BC to unravel their net impact on climate.

scholarly journals Cloud droplet activation of black carbon particles coated with organic compounds of varying solubility

2017 ◽  
Author(s):  
Maryam Dalirian ◽  
Arttu Ylisirniö ◽  
Angela Buchholz ◽  
Daniel Schlesinger ◽  
Johan Ström ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Black Carbon ◽  
Glutaric Acid ◽  
Theoretical Calculations ◽  
Water Soluble ◽  
Climate Effect ◽  
Organic Species ◽  
Surprising Effect ◽  
Study Laboratory ◽  
Ccn Activity

Abstract. Atmospheric black carbon (BC) particles are a concern due to their impact on air quality and climate. Their net climate effect is, however, still uncertain. This uncertainty is partly related to the contribution of coated BC-particles to the global CCN budgets. In this study, laboratory measurements were performed to investigate cloud condensation nuclei (CCN) activity of BC (Regal black) particles, in pure state or coated through evaporating and subsequent condensation of glutaric acid, levoglucosan (both water-soluble organics) or oleic acid (an organic compound with low solubility). A combination of Soot Particle Aerosol Mass Spectrometer (SP-AMS) measurements and size distribution measurements with Scanning Mobility Particle Sizer (SMPS) showed that the studied BC particles were nearly spherical agglomerates with a fractal dimension of 2.79 and that they were coated evenly by the organic species. The CCN activity of BC particles increased after coating with all the studied compounds and was governed by the fraction of organic material. The CCN activation of the BC particles coated by glutaric acid and levoglucosan were in good agreement with the theoretical calculations using shell-and-core model, which is based on a combination of the CCN activities of the pure compounds. The oleic acid coating enhanced the CCN activity of the BC particles, even though the pure oleic acid particles were CCN inactive. The surprising effect of oleic acid might be related to the arrangement of the oleic acid molecules on the surface of the BC cores or other surface phenomena facilitating water condensation onto the coated particles. Our results show potential in accurately predicting the CCN activity of atmospheric BC coated with organic species by present theories, given that the identities and amount of the coating species are known. Furthermore, our results suggest that even relatively thin soluble coatings (around 2 nm for the compounds studied here) are enough to make the insoluble BC particles CCN active at typical atmospheric supersaturations and thus be efficiently taken up by cloud droplets. This highlights the need of an accurate description of the composition of atmospheric particles containing BC to unravel their net impact on climate.

Composition of water-soluble organic carbon in non-urban atmospheric aerosol collected at the Storm Peak Laboratory

2013 ◽  
Vol 10 (5) ◽  
pp. 370 ◽  
Author(s):  
Vera Samburova ◽  
A. Gannet Hallar ◽  
Lynn R. Mazzoleni ◽  
Parichehr Saranjampour ◽  
Douglas Lowenthal ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Organic Carbon ◽  
Negative Ions ◽  
Water Soluble ◽  
Organic Fraction ◽  
Sugar Alcohols ◽  
Organic Species ◽  
Soluble Organic Fraction ◽  
Water Soluble Organic Carbon ◽  
Soluble Organic Carbon

Environmental context The organic fraction of atmospheric aerosols is a complex mixture of thousands of species, which play an important role in many atmospheric processes, such as absorbing and scattering solar radiation. We analysed the water-soluble organic fraction of ambient aerosol samples, and quantified over 45 carboxylic acids, sugars, sugar anhydrides and sugar alcohols. The presence of fairly high concentrations of sugars and sugar-alcohols suggests a significant biological input (e.g. pollen, fungi and bacteria) to the water-soluble organic fraction of non-urban aerosols. Abstract Water-soluble organic constituents of PM2.5 aerosol (particulate matter with an aerodynamic diameter ≤2.5µm) have not been well characterised so far. The goal of this work was to perform quantitative analysis of individual water-soluble organic species in aerosol samples collected in July of 2010 at the Storm Peak Laboratory (3210m above sea level) located in the Colorado Park Range (Steamboat Springs, CO, USA). Aqueous extracts were combined into six composites and analysed for organic carbon (OC), water-soluble organic carbon (WSOC), water-insoluble OC, inorganic ions, organic acids, lignin derivatives, sugar-alcohols, sugars and sugar-anhydrates. Analysis of higher molecular weight water-soluble organics was done using ultrahigh resolution mass spectrometry. Approximately 2400 positive and 4000 negative ions were detected and assigned to monoisotopic molecular formulae in the mass range of 100–800Da. The higher number of negative ions reflects a predominant presence of highly oxidised organic compounds. Individual identified organic species represented up to 30% of the water-soluble organic mass (WSOM). The WSOM fractions of the low molecular weight organic acids, sugars and sugar alcohols were 3–12%, 1.0–16% and 0.4–1.9%. Significant amounts of arabitol, mannitol and oxalic acid are most likely associated with airborne fungal spores and conidia that were observed on the filters using high resolution electron microscopy. Overall, higher concentrations of sugars (glucose, sucrose, fructose etc.) in comparison with biomass burning tracer levoglucosan indicate that a significant mass fraction of WSOC is related to airborne biological species.

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