Sakamakon Dole

Sakamakon Dole, mai suna bayan Malcolm Dole, ya bayyana rashin daidaito a cikin rabo na isotope mai nauyi 18" id="mwBg" rel="mw:WikiLink" title="Oxygen-18">18O (ma'auni" atom na oxygen tare da ƙarin Neutron guda biyu) zuwa mai sauƙi 16, wanda aka auna a cikin yanayi da ruwan teku. Wannan rabo yawanci ana nuna shi δ18O.

It was noticed in 1935 that air contained more 18O than seawater; this was quantified in 1975 to 23.5‰, but later refined as 23.88‰ in 2005. The imbalance arises mainly as a result of respiration in plants and in animals. Due to thermodynamics of isotope reactions, respiration removes the lighter—hence more reactive—16O in preference to 18O, increasing the relative amount of 18O in the atmosphere.

Rashin daidaito yana daidaitawa ta hanyar 2" href="./Photosynthesis" id="mwKw" rel="mw:WikiLink" title="Photosynthesis">photosynthesis. Photosynthesis yana fitar da iskar oxygen tare da wannan isotopic abun da ke ciki (watau [./Δ<sup id= 18" id="mwLA" rel="mw:WikiLink" title="Δ18O">rabo tsakanin 18 da 16O]) kamar ruwa (H2O) da aka yi amfani da shi a cikin amsawa,  wanda ke da 'yanci daga rabo na yanayi. Don haka lokacin da matakan 18O na yanayi suka isa, photosynthesis zai yi aiki a matsayin abin ragewa. Koyaya, a matsayin abu mai rikitarwa, matakin raguwa (watau canji a cikin isotope ratio) wanda ke faruwa saboda photosynthesis ba ya dogara da ruwa da shuka ta zana, kamar yadda raguwa na iya faruwa ne sakamakon fifiko na H216O - ruwa mai ɗauke da isotopes masu sauƙi, da sauran ƙananan matakai masu mahimmanci.

 Amfani da tasirin Dole 
Tun da evaporation yana haifar da ruwan teku da na ƙasa don samun rabo daban na 18 zuwa 16, tasirin Dole zai nuna muhimmancin da ya dace na photosynthesis na ƙasa da na ruwa. Cikakken cire yawan amfanin ƙasa zai haifar da canjin tasirin Dole na -2-3‰ daga darajar yanzu na 23.5‰. 

Tsayawa (zuwa cikin 0.5‰) na yanayin 18 zuwa 16 dangane da ruwan teku tun lokacin Interglacial na ƙarshe (shekaru 130,000 da suka gabata), kamar yadda aka samo daga ƙwayoyin kankara, yana nuna cewa yawan ƙasa da na ruwa sun bambanta tare a wannan lokacin.

Bambance-bambancen shekaru na tasirin Dole an gano suna da alaƙa da abubuwan da suka faru na canjin yanayi ba zato ba tsammani a yankin Arewacin Atlantic a cikin 60 kyr na ƙarshe (1kyr=1000years).[1] Babban alaƙa na tasirin Dole zuwa speleothem δ18O, mai nuni ga hazo damina, yana ba da shawarar cewa yana iya fuskantar canje-canje a ƙarancin ƙarancin latudu na ƙasa. Bambance-bambancen ma'auni na Orbital na tasirin Dole, wanda aka kwatanta da lokutan 20-100 kyr, suna mai da martani mai ƙarfi ga ƙayyadaddun ƙayyadaddun kewayar sararin samaniya da gabaɗaya, amma ba ma'ana ba.[2]

Hakanan ana iya amfani da tasirin Dole a matsayin mai ganowa a cikin ruwan teku, tare da ƙananan bambance-bambance a cikin ilmin sunadarai ana amfani da su don bin diddigin "ƙananan" ruwa da ƙayyade shekarunsa.

 Dubi kuma 

 Isotopes na iskar oxygen

 Manazarta