Impela lapho uzwa ngomgodi osogalelweni lwe-ozone obalwa amagesi abhekene nawo. Into eyinhloko yamakhemikhali edale ukwehla kokuhlushwa kwe-ozone esemkhathini yilezi chlorofluorocarbons. Lezi izinto zamakhemikhali egesi eziye zasetshenziswa kusukela zasungulwa ngo-1928. Ziyaziwa nangokuthi CFC. Aphenywa ngokucophelela, futhi kwaboniswa ukuthi izakhiwo zawo azigcini nje ngokubeka impilo yomphakathi engozini kodwa nongqimba lwe-ozone. Ngenxa yalesi sizathu, ukusetshenziswa kwayo kwakunqatshelwe.
Kulesi sihloko sizokutshela ukuthi ama-chlorofluorocarbon ayini, ziyini izici zawo nokuthi kungani abhubhisa ungqimba lwe-ozone.
Yini ama-chlorofluorocarbon
Lawa amakhemikhali akhiwe nge-carbon, fluorine, nama-athomu e-chlorine. Ngakho-ke igama layo. Lawa ma-athomu angamalungu eqembu le- ama-halocarbon ayiqembu lamagesi awanabo ubuthi noma angasha. Zasungulwa okokuqala ngqa ngo-1928 njengenye indlela yezakhi ezahlukahlukene zamakhemikhali ezazisetshenziswa eziqandisini. Kamuva zasetshenziswa njengeziphepheli emithini yokubulala izinambuzane, opende, izinto zokulungisa izinwele neminye imikhiqizo yokunakekelwa kwezempilo.
Phakathi kwama-50s nama-60s babesetshenziswa kuma-air conditioner emakhaya, ezimotweni nasemahhovisi. Konke lokhu kusetshenziswa kubangele ukuthi ama-chlorofluorocarbons ande emhlabeni jikelele. Ngaleso sikhathi ukusetshenziswa kwala makhemikhali kwakukhula cishe ngamathani metric ayisigidi ayekhiqizwa minyaka yonke kusuka nje e-United States. Kamuva yandisa ukusetshenziswa kwayo kakhulu. Ifike ezingeni lokuthi isetshenziswe njenge i-aerosol, iziqandisi, izinto ezifutha igwebu, izinto zokupakisha kanye nezincibilikisi.
Imikhiqizo ejwayelekile kakhulu ye-chlorofluorocarbon
Lawa makhemikhali awanawo umthombo wemvelo avela kuwo. Angamakhemikhali adalwe abantu ukuze asetshenziswe kaningi. Ayesetshenziswa njengeziqandisi, ama-propellants nezinyibilikisi zezimboni ekwenzeni amagwebu. Yayisetshenziswa futhi njenge-ejenti yokuhlanza lapho kwenziwa imikhiqizo ye-elekthronikhi. Ukusetshenziswa kwayo kwaba kangangokuthi umthelela ongqimbeni lwe-ozone wanda kakhulu ngesikhathi esifushane. Kwatholakala ukuthi la magesi abhubhisa i-ozone ye-stratospheric kangangokuthi imisebe yelanga eyingozi ye-ultraviolet ingafinyelela phezulu.
Phakathi kwemikhiqizo ye-chlorofluorocarbon ethandwa kakhulu sinakho okulandelayo:
- Iziqandisi kuma-air conditioner.
- Iziqandisi.
- Ama-propellants kuma-aerosols.
- Ama-inhalers wokulawula i-asthma. Kamuva lokhu kwavinjelwa ukunciphisa umthelela ku-stratosphere.
- Ama-Haloalkanes ezindizeni.
- Ukunciphisa ama-solvents.
Imiphumela emibi yama-chlorofluorocarbons asemkhathini
Njengoba kushiwo ngaphambili, la makhemikhali ayaziwa ngokulimaza ungqimba lwe-ozone. Lokhu kusho ukuthi imisebe eminingi ye-ultraviolet evela elangeni ingadlula kwi-stratosphere futhi ifinyelele ebusweni bomhlaba. Kubonakale kunemiphumela emibi eminingi empilweni yethu. Futhi ngukuthi, njengoba ziyizinhlanganisela ezahlukahlukene ezingenamakhemikhali, bekucatshangwa ukuthi ngeke zibe nangozi emkhathini. Kodwa-ke, ngokuhamba kwesikhathi kwatholakala lokho isabele ngemisebe ye-ultraviolet emkhathini, ikakhulukazi ku-stratosphere.
Lolu ngqimba lomkhathi luqukethe i-ozone ephakeme kakhulu, esisiza ukuba sinciphise imisebe ye-ultraviolet esifinyelela kithi ivela elangeni. Lokhu kugcwala okuphezulu kwe-ozone kwaziwa ngokuthi ungqimba lwe-ozone. Lapho ama-chlorofluorocarbon ehlangana nemisebe, abola nge-photolytic, okuwaguqule abe imithombo ye-inorganic chlorine. Lapho i-chlorine ikhishwa ngesimo sama-athomu, iyakwazi ukugqugquzela ukuguqulwa kwama-athomu e-ozone abe umoya-mpilo. Lokhu kusho ukuthi kusheshisa ukusabela kwamakhemikhali okwenzeka ngokwemvelo ukuguqulwa kwe-ozone ibe umoya-mpilo.
Siyakhumbula ukuthi i-molecule ye-ozone yakhiwe ama-athomu angu-3 oksijini. Umoya-mpilo womkhathi wakhiwe ama-athomu amabili omoya-mpilo. Ngale ndlela, i-chlorine isebenza njenge-catalyst yokwandisa isivinini kanye nenani lokusabela kwamakhemikhali okuguqula i-ozone ibe umoya-mpilo. Ngale ndlela ama-molecule e-ozone angafika ku-100.000 angacekelwa phansi nge-athomu ngayinye ye-chlorine ekhishwayo. Zonke lezi zizathu ukuthi kungani ama-chlorofluorocarbon exhunyaniswa nokucekelwa phansi kongqimba lwe-ozone, okubalulekile ekusivikeleni emisebeni eyingozi njengoba kuchazwe ku- ungqimba lwe-ozone nokululama kwalo.
Akukhona ukuthi lawa makhemikhali abhubhisa ngqo i-ozone etholakala ku-stratosphere, kodwa kunalokho ukuthi kudingeka ukuhlangana kwamakhemikhali okuhlukahlukene ukuze kwenzeke. Kodwa-ke, izinga okuzokhishelwa ngalo ama-chlorofluorocarbon emoyeni kwadala ukuthi kunyamalale inani elikhulu le-ozone eyizingqimba. Ukunyamalala kongqimba lwe-ozone kunemiphumela elimaza kakhulu futhi kuqhubeka kukhulisa ukungcoliswa kwamakhemikhali. Futhi i-ozone iphethe imunca imisebe yelanga eminingi ephakathi kwamaza angama-280 nama-320 nm nokuthi kuyingozi kuzo zombili izilwane nezitshalo kanye nomuntu, kunjalo.
Umgodi we-ozone
Ukusetshenziswa kwala makhemikhali ngenani elikhulu kuye kwaphumela ekudaleni izimbobo ongqimbeni lwe-ozone. Akukhona ukuthi kunembobo ngayinye lapho kungekho khona ukugxila kwe-ozone. Kumane kuyizindawo lapho ukuhlushwa kwe-ozone kungaphansi kakhulu kokujwayelekile. Lokhu kugxila kuphansi ngokwanele ukuvimbela imisebe ye-ultraviolet ukuthi ingahlali ku-stratosphere futhi ingene ebusweni boMhlaba.
Yize ama-chlorofluorocarbons enqatshelwe, ngoba anokungenwa kwamakhemikhali okukhulu futhi awancibiliki, nanamuhla, ingxenye enkulu yamakhemikhali akhishwe eminyakeni eyedlule isatholakala. Lokhu kungenxa yokuthi banesikhathi eside sokuphila emkhathini. Kusukela ngo-1987 umthetho olandelwayo waseMontreal waqaphela ukuthi lezi zinhlanganisela zamakhemikhali ziyingozi kanye nezinye izivumelwano zamazwe ngamazwe ezaholela ekuvinjweni kwalawa makhemikhali, ngoba nawo asebenza njengamagesi abamba ukushisa njengoba kuchazwe ku umphumela we-greenhouse kanye nemiphumela yawo.
Njengoba ukwazi ukubona, ama-chlorofluorocarbon anemiphumela emibi emikhulu emkhathini, kanye nasezilwaneni, ezitshalweni nakubantu. Ngiyethemba ukuthi ngalolu lwazi ungafunda kabanzi ngama-chlorofluorocarbon.
