ISHS Acta Horticulturae 819: International Symposium on Growing Media 2007
CHEMICAL AND CARBON-13 CROSS-POLARIZATION MAGIC-ANGLE SPINNING NUCLEAR MAGNETIC RESONANCE CHARACTERIZATION OF COMPOSTED ORGANIC WASTES |
| Authors: | E. Eymar, Y. Tapia, I. Frutos, A. Gárate, V. Cala |
| Keywords: | pine bark, yard trimming, sewage sludge, spent mushroom substrate, heavy metals, water-soluble organic matter, phytoremediation |
| Abstract:
To evaluate the potential to mobilize inorganic pollutants of different composted organic wastes, a chemical and spectroscopical approach was performed by using carbon-13 cross-polarization magic-angle spinning nuclear magnetic resonance (13C CPMAS NMR). Three organic mixes composted were studied: pine bark with peat (PT), yard trimming with biosolids (BS) and spent mushroom substrate (SM). A column leachate study was conducted adding 200 mg kg-1 of cadmium (Cd) to the compost, and watering with deionized water to estimate the concentration of Cd leached and the possible relationship with organic soluble complexes released by these composts. The technique of 13C CPMAS NMR is useful to describe the chemical composition and the molecular components of complex organic mixes such as these composts. The higher pH of BS and SM give them a higher tendency to form hydro-soluble organic compounds, but with a very low capacity to form soluble complexes with Cd. The highest concentration of Cd in leachates was evident in compost PT. The measurement of the absorbance at 465 nm (A4) and 665 nm (A6) and the ratio A4/A6 in the leachates can be also used as indexes to describe the hydro-soluble carbon of composted organic wastes. Despite the heavy metal content, BS and SM could be potentially used both as components for plant growing media and as amendments for phytoremediation, because of their relative low capacity to form soluble compounds with cadmium in polluted soils. | |
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