No description available.

No description available.

No description available.

The Everglades is a sub-tropical coastal wetland characterized among others by its hydrological features and deposits of peat. Formation and preservation of organic matter in soils and sediments in this wetland ecosystem is critical for its sustainability and hydrological processes are important divers in the origin, transport and fate of organic matter. With this in mind, organic matter dynamics in the greater Florida Everglades was studied though various organic geochemistry techniques, especially biomarkers, bulk and compound specific δ13C and δD isotope analysis. The main objectives were focused on how different hydrological regimes in this ecosystem control organic matter dynamics, such as the mobilization of particulate organic matter (POM) in freshwater marshes and estuaries, and how organic geochemistry techniques can be applied to reconstruct Everglades paleo-hydrology. For this purpose organic matter in typical vegetation, floc, surface soils, soil cores, and estuarine suspended particulates were characterized in samples selected along hydrological gradients in the Water Conservation Area 3, Shark River Slough and Taylor Slough. This research focused on three general themes: (1) Assessment of the environmental dynamics and source-specific particulate organic carbon export in a mangrove-dominated estuary. (2) Assessment of the origin, transport and fate of organic matter in freshwater marsh. (3) Assessment of historical changes in hydrological conditions in the Everglades (paleo-hydrology) though biomarkes and compound specific isotope analyses. This study reports the first estimate of particulate organic carbon loss from mangrove ecosystems in the Everglades, provides evidence for particulate organic matter transport with regards to the formation of ridge and slough landscapes in the Everglades, and demonstrates the applicability of the combined biomarker and compound-specific stable isotope approach as a means to generate paleohydrological data in wetlands. The data suggests that: (1) Carbon loss from mangrove estuaries is roughly split 50/50 between dissolved and particulate carbon; (2) hydrological remobilization of particulate organic matter from slough to ridge environments may play an important role in the maintenance of the Everglades freshwater landscape; and (3) Historical changes in hydrology have resulted in significant vegetation shifts from historical slough type vegetation to present ridge type vegetation.

Rice grows in saturated soil water condition and its requirement for water is highest amongst other cereal crops. In India, the southwest monsoon wind regime brings rainfall that provides a favourable environment for rice cultivation. Thus, there is significant dependency ofrice production on the southwest monsoon rainfall. Being a crop that grows across diverse climatic regions in India ranging from the humid to semi-arid, it offers possibility to explore therelationship between stable isotopic compositions in the grain organic matter with the climaticfactors relevant for its growth. In this thesis, we measured the isotopic compositions of oxygen, hydrogen and carbon of several rice genotypes that were cultivated during the southwest monsoon in diverse climatic regions across the Indian landmass. These isotopic values were then compared with the seasonalaverage values of climate factors such as relative humidity and temperature. Together with thiswe also studied the dependency of the oxygen isotope composition of the grain OM (δ18OOM) onthat of the source water (δ18OSW). Upon removal of δ18OSW effect from δ18OOM, we obtained astrong and significant relationship between the 18O enrichment in grain organic matter (definedas 18OOM) with relative humidity. The gradient recorded was 0.45‰ shift in 18OOM with 1%change in the relative humidity level. This relationship can potentially be used to estimate thepast variations in relative humidity (and by extension, can provide a measure of monsoon rainfallvariations). We further validated this relationship based on experiments carried out in aglasshouse where all the physical factors were well-monitored. Together with this, carbonisotopic composition measured in the rice grain organic matter were used to infer the water useefficiency of rice grown in different climatic settings. The stable isotope approach was furtherimplemented for studying the archaeological rice grains recovered from archaeological sites. Analysis of carbon isotopic composition of archaeological rice grains from seven archaeologicalsites (Balu, Kanmer, Ojiyana, Lahuradewa, JognaKhera, Hulas and Kunal), belonging to theHarappan civilization and other contemporary cultures provided a new suit of data on quantitativeestimate of the hydroclimatic condition (specifically relative humidity) and water availabilityduring the existence of this civilization.

Rice grows in saturated soil water condition and its requirement for water is highest amongst other cereal crops. In India, the southwest monsoon wind regime brings rainfall that provides a favourable environment for rice cultivation. Thus, there is significant dependency ofrice production on the southwest monsoon rainfall. Being a crop that grows across diverse climatic regions in India ranging from the humid to semi-arid, it offers possibility to explore therelationship between stable isotopic compositions in the grain organic matter with the climaticfactors relevant for its growth. In this thesis, we measured the isotopic compositions of oxygen, hydrogen and carbon of several rice genotypes that were cultivated during the southwest monsoon in diverse climatic regions across the Indian landmass. These isotopic values were then compared with the seasonalaverage values of climate factors such as relative humidity and temperature. Together with thiswe also studied the dependency of the oxygen isotope composition of the grain OM (δ18OOM) onthat of the source water (δ18OSW). Upon removal of δ18OSW effect from δ18OOM, we obtained astrong and significant relationship between the 18O enrichment in grain organic matter (definedas 18OOM) with relative humidity. The gradient recorded was 0.45‰ shift in 18OOM with 1%change in the relative humidity level. This relationship can potentially be used to estimate thepast variations in relative humidity (and by extension, can provide a measure of monsoon rainfallvariations). We further validated this relationship based on experiments carried out in aglasshouse where all the physical factors were well-monitored. Together with this, carbonisotopic composition measured in the rice grain organic matter were used to infer the water useefficiency of rice grown in different climatic settings. The stable isotope approach was furtherimplemented for studying the archaeological rice grains recovered from archaeological sites. Analysis of carbon isotopic composition of archaeological rice grains from seven archaeologicalsites (Balu, Kanmer, Ojiyana, Lahuradewa, JognaKhera, Hulas and Kunal), belonging to theHarappan civilization and other contemporary cultures provided a new suit of data on quantitativeestimate of the hydroclimatic condition (specifically relative humidity) and water availabilityduring the existence of this civilization

Rice grows in saturated soil water condition and its requirement for water is highest amongst other cereal crops. In India, the southwest monsoon wind regime brings rainfall that provides a favourable environment for rice cultivation. Thus, there is significant dependency ofrice production on the southwest monsoon rainfall. Being a crop that grows across diverse climatic regions in India ranging from the humid to semi-arid, it offers possibility to explore therelationship between stable isotopic compositions in the grain organic matter with the climaticfactors relevant for its growth. In this thesis, we measured the isotopic compositions of oxygen, hydrogen and carbon of several rice genotypes that were cultivated during the southwest monsoon in diverse climatic regions across the Indian landmass. These isotopic values were then compared with the seasonalaverage values of climate factors such as relative humidity and temperature. Together with thiswe also studied the dependency of the oxygen isotope composition of the grain OM (δ18OOM) onthat of the source water (δ18OSW). Upon removal of δ18OSW effect from δ18OOM, we obtained astrong and significant relationship between the 18O enrichment in grain organic matter (definedas 18OOM) with relative humidity. The gradient recorded was 0.45‰ shift in 18OOM with 1%change in the relative humidity level. This relationship can potentially be used to estimate thepast variations in relative humidity (and by extension, can provide a measure of monsoon rainfallvariations). We further validated this relationship based on experiments carried out in aglasshouse where all the physical factors were well-monitored. Together with this, carbonisotopic composition measured in the rice grain organic matter were used to infer the water useefficiency of rice grown in different climatic settings. The stable isotope approach was furtherimplemented for studying the archaeological rice grains recovered from archaeological sites. Analysis of carbon isotopic composition of archaeological rice grains from seven archaeologicalsites (Balu, Kanmer, Ojiyana, Lahuradewa, JognaKhera, Hulas and Kunal), belonging to theHarappan civilization and other contemporary cultures provided a new suit of data on quantitativeestimate of the hydroclimatic condition (specifically relative humidity) and water availabilityduring the existence of this civilization.