Showing 2 results for Carbonates
A. Karimi, H. Khademi,
Volume 16, Issue 61 (10-2012)
Abstract
Magnetic susceptibility measurement is a simple and quick technique for characterizing soils and sediments and describing soil-forming processes. The interpretation of soil magnetic susceptibility data needs sufficient knowledge about the factors affecting this parameter. To identify the effects of parent material, gypsum and calcium carbonate equivalent, 42 samples were taken from horizons of soils developed on loessial, alluvial, granitic and marly materials in southern Mashhad. Gypsum and carbonates of soil samples were removed by successive washing with distilled water and diluted HCl, respectively. Magnetic susceptibility of bulk samples (lfbulk), gypsum free samples (lfGf), gypsum and carbonates free samples (lfGCf) and gypsum, carbonates and sand free samples (lfGCSf) was measured. The results revealed a strong 1:1 correlation between the measured and calculated lfGf and lfGCf. Despite the high amounts of gypsum and carbonates in soils developed on marls, their lfbulk was much more than that of the other soils and reached up to 121.8×10-8m3 kg-1. In contrast, the lfbulk values of saprolitic granite were less than 10.4×10-8m3 kg-1. The lfbulk values of loessial and alluvial soils were less than those of marly soils but higher than those of soils developed on saprolitic granite. lfbulk values were negatively correlated with the amount of sand. However, reduction in magnetic susceptibility values of marly soils after removing sand reflects the different nature of this soil. The correlation between lfbulk and amount of silt and clay is positive, but the magnetic susceptibility values are more sensitive to clay percentage, indicating the more important contribution of clay to magnetic susceptibility values. The results of this study highlight the role of parent materials, gypsum and carbonates in the soil magnetic susceptibility values that should be considered.
F. Khayamim, H. Khademi, B. Stenberg, J. Wetterlind,
Volume 19, Issue 72 (8-2015)
Abstract
Vis-NIR spectroscopy has been introduced as a non-destructive, fast, and cheap technique, with minimal sample preparation and no loss or damage to the environment. No investigation has yet been carried out to examine the ability of this method to estimate soil properties in Iran. The objective of this research was to investigate the capability of Vis-NIR spectroscopy to predict the amount of organic matter, carbonate and gypsum in surface soils of Isfahan province. A total of 248 surface soil samples were collected from the study area. Soil organic matter content, gypsum and carbonates percentages were measured by standard laboratory methods. Soil spectral analyses were performed by a field spectrometer using 350-2500 nm wavelength range. Different pre-processing methods were evaluated after recording the spectra. Partial least squares regression was used to predict soil parameters. R2 values for organic matter, carbonates and gypsum were 0.61, 0.45 and 0.8, respectively. Based on RPD (Ratio of Prediction to Deviation) values, the precision of prediction model for gypsum was quite good, and acceptable for organic matter, whereas the prediction of the model for soil carbonates was poor. Consequently, vis-NIR spectroscopy is capable of predicting some soil properties simultaneously and the model accuracy is acceptable.
