Oxygen hydrological cycle

In biologically productive lakes which also develop a thermocline in summer, the bottom water may become depleted in oxygen, leading to a change from oxidizing to reducing conditions. As a result, the potential exists for remobilization of nutrients and metals from bottom sediments to the water column, one more example of how alterations in master variables in the hydrological cycle, in this case the redox status, can affect the fate and influence of pollutants. 

Major changes in atmospheric composition have, in turn, been held responsible for so-called snowball Earth events, characterized by low-latitude glaciation and effective shutdown of the hydrological cycle, —2.3 Gyr (coinciding with the rise of oxygen), and 750 Myr and 600 Myr ago (e.g., Kirschvink, 1992 Hoffman et al., 1998 Kirschvink et al., 2000 Hoffman and Schrag, 2002). Loss of CH4 accompanying the rise of... 

Gat, J.R. 1996. Oxygen and hydrogen isotopes in the hydrologic cycle. Annual Review of Earth and Planetary Sciences 24 225-262. 

Both, (a) changes in the isotopic composition of the hydrological cycle due to, e.g., climate variations and (b) changes in the carbon and oxygen fluxes between the reservoirs therefore can induce changes in the oxygen isotopic composition of atmospheric CO, and Oj. Dynamically, after a perturbation a new atmospheric steady state of the oxygen isotope ratios establishes within a few years in the case of 0/ 0 in CO, and within about 1200 years in... 

FIGURE 6.1 The atmosphere is a layer of gas, most of which is concentrated in a very thin region jnst above Earth s surface. It serves as a sonrce of some essential materials protects life on Earth from deadly electromagnetic radiation transports water as part of the hydrologic cycle participates in the carbon, oxygen, and sulfur cycles and is an essential part of natural capital. 

Note An excellent collection of basic isotope data and discussion of case studies is provided by publications of the International Atomic Energy Agency, included at the end of the reference list. Especially useful is the collection of papers in Stable Isotope Hydrology Deuterium and Oxygen-18 in the Water Cycle, IAEA, Vienna, 1981. Fritz and Fontes (1980 and 1986) are the editors of the Handbook of Environmental Isotope Geochemistry, which contains valuable information on the stable hydrogen and oxygen isotopes. 

Stable Isotope Hydrology Deuterium and Oxygen-18 in the Water Cycle, 339 pp, 1981. 

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