Efficiency of oxidation in wet digestion procedures and influence from the residual organic carbon content on selected techniques for determination of trace elements

2002 ◽  
Vol 17 (9) ◽  
pp. 1121-1125 ◽  
Author(s):  
M. Wasilewska ◽  
W. Goessler ◽  
M. Zischka ◽  
B. Maichin ◽  
G. Knapp
1987 ◽  
Vol 59 (2) ◽  
pp. 63-65
Author(s):  
Raina Niskanen ◽  
Väinö Mäntylahti

Drying of three mineral soil samples (clay content 4—58 %, organic carbon content 1—5 %) equilibrated at 75.5 % relative humidity was studied. The soils were dried in an oven at +50°C, +70°C and + 105°C for 4 and 8 hours and in a desiccator over pure concentrated H2SO4 and P2O5. Drying over desiccants for 8 hours removed less water than drying at + 50°C. Drying over desiccants for 3—7 days was as efficient as drying at +70°C, for 14—24 days as efficient as 4 hours of drying at + 105°C. Eight hours of drying at + 105°C seemed to be too drastic, because it caused a greater weight loss in the clay sample of 5 % organic carbon content than did prolonged desiccant-drying. Drying at + 70°Cremoved as much water from fine sand which contained 4 % clay as prolonged desiccant-drying.


2019 ◽  
Vol 51 (3) ◽  
pp. 342-347 ◽  
Author(s):  
V. R. Angelova ◽  
V. I. Akova ◽  
K. I. Ivanov

The aim of this study was to compare the most commonly used methods for the determination of organic carbon (OC) and organic matter (SOM), and evaluate the capability of LOI (loss on ignition method) to estimate OC, using reference soils, compost and sludge as standards. The use of a titrimetric endpoint (adding phosphoric acid prior to titration) is more suitable for assessing the level of organic carbon in soils with low, medium, high and very high content. The use of a photometric endpoint is more appropriate for samples of medium and high carbon content. LOI 400 and LOI 450 may also be used for the determination of samples with a high organic content whereas LOI 450 - in the determination of samples with an average organic content. LOI 450 can be used to evaluate SOC in a wide range of organic matter concentrations (3-55%). Indirect assessment of the organic carbon content or organic matter using a correction coefficient is not very accurate for samples with average organic carbon content. Keywords: methods, organic carbon, organic matter, certified samples


1983 ◽  
Vol 55 (2) ◽  
pp. 109-117
Author(s):  
Raili Jokinen

A total of 430 topsoil samples were collected from ten fields of the Viikki Experimental Farm, University of Helsinki. Particle size distribution, organic carbon content, pH(CaCl2), exchangeable Ca, Mg, K contents, plant available P (Bray 1), 1 M KCI extractable (Al+H) content and effective cation exhange capacity of the soils were determined. The coefficient of variation was used as indicator of the variability of soil properties with in each field. The lowest coefficients of variation were observed for pH(CaCl2) and the highest for exchangeable Mg 1 M KCI extractable (Al+H) and effective cation exchange capasity. The results indicate that from 1 (pH(CaCl2)) to 33 (exchangeable Mg) samples per hectare are needed from individual fields for strict level of accuracy in estimation of the soil properties. For determination of soil type (according to clay content) and organic carbon content on average 8 samples, and for the plant available P (Bray 1) and exchangeable Mg and K contents 10 to 16 samples per hectare appear sufficient. Four samples suffice for a less stringent, lax accurate determination of all properties. The variability of soil properties is discussed from the viewpoint of agricultural advisory work and field experiments for agricultural research.


1980 ◽  
Vol 17 (2) ◽  
pp. 254-265 ◽  
Author(s):  
Joan D. Willey ◽  
Robert A. Fitzgerald

Organic matter, mineralogy, and texturally-related qualities combine to control the total concentration and reactivity of trace metals in the sediments of the Miramichi estuary. Concentrations of lignin-rich organic matter, up to 10% of the total sediment weight in the central estuary, correlate with analytical results for trace elements which show that more than 40% of the total Mn, Zn, and Cu is held in the oxidizable and organically-bound form. Mineralogical influences are most obvious in the river portion of the system where total Mn concentrations average 695 μg/g, Zn averages 282 μg/g, Cu averages 32 μg/g, and Pb averages 200 μg/g in the less than 63 μm size fraction of the sediments. In the marginal marine Miramichi Bay, total concentrations of these four trace elements in the fine sediment fraction are diminished by 9–57%, with respect to the equivalent size fraction of the river sediments.The concentration of all trace elements in the coarse fraction (> 63 μm) is considerably less as compared with the fine fraction. In these sediments mineralogical associations are more pro nounced. Very high organic carbon content (up to 23%) is associated with sediments in which more than 25% of the Mn, Zn, and Cu is organically bound. Weak acid leachable Ca in the coarse sediments of the bay is 21 times higher as compared with the equivalent river sediment fraction and this CaCO3 indication is associated with a twofold increase in total Cu and Pb.When compared with sediments from other areas of eastern Canada, the Miramichi sediments have at least twice as much weak acid leachable Zn, and this higher level of reactive metal is associated with high organic carbon content in the top 15 cm of cored sediments. Suggested sources for this recent addition of metal in association with organic matter are the mining activities as well as urban and industrial effluents.


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