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Water-cation bridges in soil organic matter
Starostová, Anna ; Komendová, Renata (oponent) ; Kučerík, Jiří (vedoucí práce)
Degradation of soil in process of salinization, increasing temperature and following decreasing precipitation in recent years lead to expand of arid and semi-arid areas (now covering one-third of Earth’s land). Furthermore, being a global environmental problems could grow into a serious crisis worldwide if they were not solved properly. In this diploma thesis we connected all these issues and focused on contributing to the better understanding the role of sodium cations on water binding in soil organic matter under arid and semi-arid conditions. Our aim was to investigate the processes of formation and stability of water molecule bridges and cation-water molecule bridges in soil organic matter, strength of water binding and amount of bound water using differential scanning calorimetry. The saturation in sodium cation was studied in two concentration regions in order to simulate natural conditions in soils by lower Na-saturation (less than 100% saturation of binding sites) and over-saturated samples (more than 100% Na-saturation of binding sites) representing salty soils. Results confirmed the importance of ability of soil to gain water from air moisture, in fact, water content in soil increased with increasing relative humidity. It was observed that at higher water content in soil is water less strongly bound, which caused that water was easier to be released from soil. That seems to keep balance between soil and air humidity and therefore also optimal humidity in soil. Presence of sodium cations in samples had a negligible effect on amount of water in samples saturated up to 100% but facilitated better water binding in over-saturated samples. In over-saturated samples was also observed a stronger water binding even at higher water contents. Water molecule bridges were more stable in samples containing Na+. In fact, highest stability was observed in 10% saturated samples and increasing Na+ concentration caused a decrease in stability of molecule bridges. To sum up, formation of cation-water bridges showed to stabilize soil rigidity and have an impact on the strength and amount of water bound in soil which are crucial aspects of soil quality. Further research is needed in this field to bring more results that can help to optimize soil management in arid areas and also other areas with soil degradation.
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Water-cation bridges in soil organic matter
Starostová, Anna ; Komendová, Renata (oponent) ; Kučerík, Jiří (vedoucí práce)
Degradation of soil in process of salinization, increasing temperature and following decreasing precipitation in recent years lead to expand of arid and semi-arid areas (now covering one-third of Earth’s land). Furthermore, being a global environmental problems could grow into a serious crisis worldwide if they were not solved properly. In this diploma thesis we connected all these issues and focused on contributing to the better understanding the role of sodium cations on water binding in soil organic matter under arid and semi-arid conditions. Our aim was to investigate the processes of formation and stability of water molecule bridges and cation-water molecule bridges in soil organic matter, strength of water binding and amount of bound water using differential scanning calorimetry. The saturation in sodium cation was studied in two concentration regions in order to simulate natural conditions in soils by lower Na-saturation (less than 100% saturation of binding sites) and over-saturated samples (more than 100% Na-saturation of binding sites) representing salty soils. Results confirmed the importance of ability of soil to gain water from air moisture, in fact, water content in soil increased with increasing relative humidity. It was observed that at higher water content in soil is water less strongly bound, which caused that water was easier to be released from soil. That seems to keep balance between soil and air humidity and therefore also optimal humidity in soil. Presence of sodium cations in samples had a negligible effect on amount of water in samples saturated up to 100% but facilitated better water binding in over-saturated samples. In over-saturated samples was also observed a stronger water binding even at higher water contents. Water molecule bridges were more stable in samples containing Na+. In fact, highest stability was observed in 10% saturated samples and increasing Na+ concentration caused a decrease in stability of molecule bridges. To sum up, formation of cation-water bridges showed to stabilize soil rigidity and have an impact on the strength and amount of water bound in soil which are crucial aspects of soil quality. Further research is needed in this field to bring more results that can help to optimize soil management in arid areas and also other areas with soil degradation.
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