Soil mineral structural water loss during loss on ignition analyses

Abstract

Sun, H., Nelson, M., Chen, F. and Husch, J. 2009. Soil mineral structural water loss during loss on ignition analyses. Can. J. Soil Sci. 89: 603Á610. Water loss from soil minerals has been known to cause errors in the determination of soil organic matter when the loss on ignition (LOI) method is used. Unfortunately, no known published studies reliably quantify the range of structural water in the soil. To do this, 15 common reference minerals were analyzed by LOI to obtain their individual water loss. In addition, 14 upland, loamy soil samples and 3 wetland/hydric soil samples with varied mineral contents were analyzed to collect their X-ray powder diffraction spectra. Based upon X-ray spectra peak intensities, the modal abundance of minerals in each soil sample was determined using the RockJock computer program. The resultant modal weight percentages of all identified minerals in each soil sample were then multiplied by the LOI value for each mineral to obtain the mineral structural water loss (SWL) of that soil sample. For the 17 soil samples analyzed, the range of mineral water loss is 0.56 to 2.45%. Depending on the LOI values of the soil samples, the SWL:LOI ratios range from 0.04 to around 1.00. The SWL:LOI ratios are particularly low for top wetland soil when the LOI value is higher. The ratios are lower for surface soil samples than for subsurface soil samples because of the high LOI values in surface soil samples. Understanding soil mineral water loss and its relation to the LOI patterns from various environments is important for the accurate evaluation of soil organic matter when the LOI method is used.Key words: Mineral, structural water, loss on ignition Sun, H., Nelson, M., Chen, F. et Husch, J. 2009. Perte structurelle d'eau par les mine´raux du sol lors des analyses de perte par calcination. Can. J. Soil Sci. 89: 603Á610. On sait que l'eau perdue par les mine´raux du sol cause des erreurs lorsqu'on s'efforce de calculer la quantite´de matie`re organique dans le sol par la me´thode d'analyse de perte par calcination (LOI). Malheureusement, aucune des e´tudes publie´es ne quantifie de manie`re fiable la variation de l'eau structurelle dans le sol. Pour y reme´dier, les auteurs ont analyse´15 mine´raux de re´fe´rence communs par la LOI afin d'en mesurer la perte d'eau. Ils ont aussi analyse´14 e´chantillons de sol loameux des plateaux et 3 e´chantillons de sol hydrique des terres humides afin de recueillir le spectre de leur poudre par diffraction des rayons X. En partant de l'intensite´des pics obtenus aux rayons X, ils ont e´tabli l'abondance modale des mine´raux dans chaque e´chantillon graˆce au logiciel RockJock. Les pourcentages modaux ponde´re´s des mine´raux identifie´s dans chaque e´chantillon qui en re´sultent ont ensuite e´te´multiplie´s par la valeur LOI de chaque mine´ral, ce qui a donne´la perte structurelle d'eau (SWL) du mine´ral pour l'e´chantillon. Sur les 17 e´chantillons examine´s, la perte d'eau des mine´raux varie de 0,56 % a`2,45 %. D'apre`s la valeur LOI des e´chantillons, le ...

Recent rates of sedimentation on irregularly flooded Boreal Baltic coastal wetlands: Responses to recent changes in sea level

“…Using the LOI method to estimate soil organic matter can be influenced by loss of clay bonded water at high temperatures (Sun et al, 2009). However, this is unlikely to have significantly affected the results in this study due to the very low percentages of clay in the samples (typically ~1 %).…”

The biogenicity of modern terrestrial roll-up structures and its significance for ancient life on land

“…We used dry mass, loss on ignition (LOI; Dean, 1974) at 450 °C for 10 h to estimate the content of organic matter of 10 subsamples of roll‐ups and 10 of non‐roll‐ups per site. Although widely used to measure organic matter, LOI is subject to overestimation due to loss of structural mineral water (Sun et al. , 2009).…”

Mobilization of arsenic, lead, and mercury under conditions of sea water intrusion and road deicing salt application

“…This disproportional high Naconcentration created the field sodic soil condition and caused soil dispersion. Based on Sun et al (2009, their Table 5), soil organic matter contents in the top soil at the studied I-95 transects ranged from 2.11% to 4.08% based on the loss on ignition (LOI) method. Therefore, dispersion of soil organic matter exists as well.…”