Oxygen Isotope Perturbation and Its Effects on Temperature and Essay

Oxygen Isotope Perturbation and Its Effects on Temperature and Salinity in the Bay of Bengal - Essay Example Oxygen isotope ratio is a climatic proxy, an environmental variable, and it assists climatologists, including paleoclimatologists, to determine certain important climatic parameters, both existing and past, from it. (UNST 232a Mentor Section Assignment 5) Another phenomenon the isotopes are involved in is that oxygen accumulates in the calcium carbonate (CaC) of the shells of marine animals called foraminifera -"Forams". The isotope ratio in the shells depends upon on the temperature and existing isotope ratio of the water in which the animals live or lived. Over periods of time these animals die and their shells descend to the bottom of the sea and form layers that present researchers with important data from which past temperature and isotope ratios can be determined. (UNST 232a Mentor Section Assignment 5) The isotope ratio in any singular stretch of water changes over time. Water molecules made up of the lighter isotope evaporate easily leaving water molecules with the heavier one back in the seawater. When the evaporated water precipitates back into the sea there is little change in the ratio but when the water vapour precipitates on land the lighter isotope is transported to land from where it may come back to the sea via rivers and other waterways or it may remain trapped for thousands of years in the form of ice if it is precipitated as snow on places like the polar icecaps and high mountain tops. (UNST 232a Mentor Section Assignment 5) During normal times the isotope ratio in sea and ocean water is fairly constant but during glacial periods when the icecaps advance beyond normal limits the isotope ratio shifts in favour of for obvious reasons. This is in a comparative sense to normal times. (Oceanography 540, 2002) The isotope ratio is expressed as delta (lower case) with the isotope contents expressed in parts per thousand (per mille) as the following equation demonstrates. = - / x 1000 Higher negativity in indicates greater depletion. (UNST 232a Mentor Section Assignment 5) The standard in this case is of 'Standard Mean Ocean Water' or 'SMOW'. (Oceanography 540, 2002) 3. The 'Foram' Fractionation Factor The foraminifera species being investigated in this report is the planktonic