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i-ozoni, umoyamkhathi — isiZulu
Lena yi-triatomic oxygen (O3) eyakheka kwingxenye ephezulu yomkhathi, cishe ebangeni elingamakhilomitha angama 20-25 kusuka phansi emhlabeni. (Qaphela ukuthi i-oksijini esiyiphefumulayo yi-oksijini engama molekhyuli, okusho i-O2). Umoyamkhathi wakheka ngenxa yokuhlakazeka kwamanye amamolekhyuli e-oksijini bese kuthi ama-athomi “ahlakazekile noma awuvanzi” ahlangane namamolekhyuli e-oksijini yoqobo ukuze kwakheke i-triatomic oxygen. Ngaphansi kwenzinga okwakheka kulona umoyamkhathi, i-triatomic ozone iyehla kancane kancane iye phansi futhi endleleni ebheke ezansi iyaguquka ngokushesha ibe ngamamolekhyuli e-oksijini ajwayelekile. Umoyamkhathi usemqoka kithina ngoba umunca imisebe enobungozi futhi ngalokho-ke uvimbela umthamo omkhulukazi wemisebe evela elangeni ingakwazi ukufinyelela phansi emhlabeni. Empeleni umoyamkhathi usivikela emisebenzi yelanga eshisa ngokweqile (engabangela umdlavuza kwesikhumba kanye nongwengwezi olwenza amehlo angaboni kahle). Ngasekupheleni kweminyaka yawo-1960 nasekuqaleni kweminyaka yawo-1970, kwatholakala ukuthi kunokuncipha okukhulu komoyamkhathi engxenyeni ephezulu yomkhathi. Ngenxa yokuthi sasikhiqiza umthamo omkhulu wama-chlorofluorocarbons (CFCs) akhuphukayo aye phezulu emkhathini futhi sinolwazi lokuthi ama-CFCs ahlukanisa futhi ahlakaze umoyamkhathi, lokho kwasibonisa ukuthi kusho ukuthi ukungcoliseka komoya yikona okuyimbangela yokuncipha komoyamkhathi. Ngokubona imiphumela yokuba nomoyamkhathi omncane kakhulu, kwabanjwa ingqungquthela yamazwe omhlaba (bheka i-“international convention”) e-Montreal, kwelase-Canada. Lapho kwagunyazwa ukwamukelwa kwe-Montreal Protocol ngowe-1987, okuyisivumelwano esanqabela ngokuphelele futhi ngokushesha konke ukukhiqizwa kwama-CFCs. Ngisho nangaphambi kokuba kuqaliswe ukusebenza kwemigomo ye-Montreal Protocol (isiVumelwano), unqenqema lomoyamkhathi olwase lucekeleke phansi lwaqala ukubuyela esimweni salo saphambili. Kusukela lapho-ke, sesitholile ukuthi umthamo womoyamkhathi uyakhuphuka noma unciphe ngenxa yezimbangela zemvelo ezingakaziwa kahle kuze kube manje. Asazi-ke ukuthi isiVumelwano sase-Montreal saba nomthelela ongakanani ongwengwezini lomoyamkhathi, kodwa okungenani sikwazile ukunciphisa umthamo wama-CFC akhiqizwayo, angena emkhathini, futhi sifundile ukuthi abantu bayakwazi ukuthatha izinyathelo ngokubambisana ukufezekisa injongo ethile yezemvelo, uma nje isimo okubhekenwe naso sinobungozi obukhulu.
