《Kula da daidaitaccen makamashi 维持能量的平衡》

【Kula da daidaitaccen makamashi - Labarin Rayuwa a Duniya 维持能量的平衡下编-地球生命编】

Ma'anar da sararin samaniya shirya duk wannan? Wataƙila ci gaba da rayuwa da wayewa shine amsarsa, a matsayinsa na ɗan adam, ya kamata ya ɗauki nauyin kare wayewar duniya, kare yawan rayuwar duniya ne mafi kyawun godiya.

     Duniya ta farko, gwagwarmayar makamashi tsakanin narkakkar dutse da sanyaya (shekaru biliyan 4.6 zuwa 4.0 da suka wuce). A cikin kewaya daɗaɗɗiyar farantin da ke kewaye da Rana (protoplanetary disk), ƙananan taurari (planetesimals) suka haɗu ta hanyar karo da juna suka kafa duniya ta farko. Ƙarfin motsi (kinetic energy) ya koma zafi, yanayin zafin saman duniya ya wuce 1200°C, wanda ya haifar da tekun magma a duk faɗin duniya. Ƙarfe mai nauyi (iron) da nickel sun nutse zuwa tsakiyar duniya, suna sakin ƙarfin nauyi (gravitational potential energy) kimanin 10³¹ joules, wanda ya ƙara dumama cikin duniya. Abubuwan silicates masu sauƙi sun tashi sama, suna sanyaya a hankali suka kafa ɓawon burodi na farko. Abubuwa masu raguwar rabin rayuwa mai tsawo kamar uranium-238, thorium-232, potassium-40 suna ruɓe (radioactive decay), suna samar da tushen zafi na dogon lokaci (har yau suna ba da gudummawar kusan 50% na zafin cikin duniya). Gudun convection a cikin mantle yana ɗaukar zafi daga ciki zuwa sama, fashewar aman wuta tana sakin makamashi mai yawa, don guje wa narkewar da ba ta dace ba. Duniya ta cimma daidaito mai motsi (dynamic balance) tsakanin sanyayawar radiation (Stephen-Boltzmann law) da samar da zafi daga ciki (radioactive decay), don guje wa zama dutse matacce. Fashewar aman wuta tana sakin H₂O, CO₂, N₂, CH₄, NH₃, da sauransu, suna samar da yanayi mai ragewa (reducing atmosphere). Wani ɓangare na ruwa mai yiwuwa ya fito ne daga duwatsun da suka fado daga sama waɗanda suke da ruwa (kamar carbonaceous chondrites) suna kai ruwa. Babban adadin CO₂ da CH₄ yana kiyaye yanayin zafin saman duniya, yana hana daskarewar tekuna (hasken rana na farko ya kai kashi 70% kawai na yanzu) yana kiyaye daidaiton yanayin greenhouse. Ruwan teku yana narkar da ions daga duwatsun aman wuta (kamar Na⁺, Cl⁻), yana fara zagayowar ilimin kimiyar ƙasa (geochemical cycles).

     Kimanin shekaru biliyan 4.5 da suka wuce, wani jiki mai girman duniyar Mars ya afka wa duniya a karkace, ya kori abubuwa da suka haɗu suka kafa wata, karkatar da kullin duniya ya haifar da sauyin yanayi. Tasirin Theia ya saki makamashi 10³² joules, ya sake fasalin tsarin mantle, ya hanzarta bambance-bambancen core (core differentiation). Bayan tekun magma ya sanyaya a zamanin Hadean, ɓawon dutse na basalt da granite sun bambanta a hankali. Gudun convection na mantle na gida ya haifar da ayyukan ginin ƙasa na farko, amma bai kai ga tsarin faranti na zamani ba. Ruwa mai ruwa, yanayi, da matakan sinadarai (chemical gradient) sun kafa "matakan makamashi", suna samar da matsakaici don haɓakar ƙwayoyin halitta na gaba. Bakin ramin aman wuta da maɓuɓɓugar ruwan zafi a cikin teku sun zama wuraren gwaje-gwaje na haɗuwa marasa rai (kamar sulfide na ƙarfe-nickel yana haɓaka samuwar kwayoyin halitta). Narkakkar dutse da sanyayawar duniya ta farko sun shimfiɗa tushe don mataki na gaba - "halayen sinadarai" - a cikin tekuna masu tafasa da yanayi mai cike da walƙiya, makamashi zai haifar da ƙwayoyin da suka fi rikitarwa, kuma a ƙarshe ya nufi...