The term water resources refers to natural waters (vapor, liquid, or solid) that occur on the Earth and that are of potential use to humans. These resources include oceans, rivers, lakes, groundwater, and glaciers. The Earth has plenty of water, over 1.4 × 109 km3. However, 97% of global water is saline seawater. Of the 3% that is freshwater, nearly 70% is locked in the polar icecaps and glaciers. The majority of nonglacier freshwater is groundwater (98%). Surface freshwater (rivers and lakes), which has historically served most human needs, constitutes only a small fraction of the Earth’s water resources. Water interacts with minerals, soils, sediments, and rocks, and hence studies of Earth materials have a direct bearing on water resources. Studies of the acquisition, mobility, and fate of elements and isotopes in water provide valuable signatures for tracking water cycles at regional and global scales and are essential for the development of remediation technologies for contaminated water.
October 2013 - Nitrogen and Its (Biogeoscosmo) Chemcial Cycling
Nitrogen is the most abundant element in Earth’s atmosphere and a key component of the biosphere. It is also a critical part of the surface/near-surface cycling of nutrients, thus directly impacting our lives. Changes in the biogeochemical cycling of nitrogen through Earth’s history could reflect fundamental changes in its pathways from inorganic to biological reservoirs in response to change in the environment (e.g. oxygen fugacity in the atmosphere and oceans). Recognition of the importance of nitrogen to life on Earth, and likely elsewhere in the Solar System, has led to the mantra “Follow the Nitrogen” as one vehicle for focusing efforts in the search for extraterrestrial life. Nitrogen serves as a useful tracer of the transfer of “organic” signatures into the deep Earth (in records preserved in metamorphic and igneous rocks and in volcanic gases and rocks). It has been speculated that biological fixation of nitrogen and storage in rapidly forming continental crust has led to drawdown of nitrogen from the early-Earth atmosphere, strongly influencing the chemical evolution of the atmosphere and related surface conditions.