Impela lapho uzwa ngomgodi osogalelweni lwe-ozone obalwa amagesi abhekene nawo. Into eyinhloko yamakhemikhali edale ukwehla kokuhlushwa kwe-ozone esemkhathini yilezi chlorofluorocarbons. Lawa amakhemikhali anegesi asetshenziswa selokhu aqala ukusebenza ngo-1928. Aphinde aziwa ngegama elithi CFC. Baphenywa ngokuningiliziwe futhi bakhombisa ukuthi izindawo zabo azisengozini yezempilo yomphakathi kuphela kepha nongqimba lwe-ozone. Ngakho-ke, ukusetshenziswa kwayo kwakungavunyelwe.
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, i-refrigerant, i-ejenti yokushaya amagwebu, izinto zokupakisha kanye ne-solvents.
Imikhiqizo ejwayelekile kakhulu ye-chlorofluorocarbon
Lawa makhemikhali awanawo umthombo wemvelo avela kuwo. Angamakhemikhali adalwe ngabantu asetshenziswa kakhulu. Zazisetshenziswa njengeziqandisi, izinto eziphumisayo nezinyibilikisi zezimboni ekwakheni amagwebu. Iphinde yasebenza njenge-ejenti yokuhlanza ekwakhiweni kwemikhiqizo kagesi. Ukusetshenziswa kwayo kwaba nomthelela onje ngendwangu ye-ozone yanda kakhulu ngesikhathi esifushane. Lawa magesi ayaziwa ngokucekela phansi i-ozone ye-stratospheric ngezinga lokuthi imisebe eyingozi yelanga ye-ultraviolet ingafinyelela phezulu.
Phakathi kwemikhiqizo ye-chlorofluorocarbon ethandwa kakhulu sinakho okulandelayo:
- Isiqandisi sikuma-conditioner omoya.
- Iziqandisi.
- Ama-propellants kuma-aerosols.
- Ama-inhalers wokulawula i-asthma. Kamuva lokhu kwavinjelwa ukunciphisa umthelela ku-stratosphere.
- Ama-Haloalkanes ezindizeni.
- Ama-solvents afuna i-grease ngokushesha.
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.
Kule ungqimba lomkhathi kunenqwaba ye-ozone esisiza ukunciphisa imisebe ye-ultraviolet evela elangeni. Le ngxube enkulu ye-ozone yaziwa ngokuthi ungqimba lwe-ozone. Lapho ama-chlorofluorocarbon ehlangana nemisebe, aqala ukubola kwe-photolytic okusiguqula sibe yimithombo ye-chlorine engaphili. Lapho i-chlorine ikhishwa ngendlela yama-athomu ayakwazi ukuqinisa ukuguqulwa kwama-molecule e-ozone abe yi-oxygen. Lokhu kusho ukuthi isheshisa ukusabela kwamakhemikhali okwenzeka ngokwemvelo kokuguqula i-ozone ibe yi-oxygen.
Siyakhumbula ukuthi i-molecule ye-ozone yakhiwe ngama-athomu e-oksijini ama-3. Umoya-mpilo wakhiwe ngama-athomu amabili e-oxygen. Ngale ndlela, i-chlorine isebenza njengesikhuthazi ekwandiseni izinga nenani lokuphendula kwamakhemikhali okuguqula i-ozone ibe yi-oxygen. Ngakho-ke ama-molecule e-ozone angafika ku-100.000 angacekelwa phansi nge-athomu ngayinye ye-chlorine ekhishwayo. Zonke lezi zizathu ukuthi kungani ama-chlorofluorocarbon ahlobene nokucekelwa phansi koqweqwe lwe-ozone.
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 ngesilinganiso esikhulu kuholele ekwakhiweni kwemigodi kusendlalelo lwe-ozone. Akukhona ukuthi kunomgodi ngokwawo lapho kungekho khona ukuhlushwa kwe-ozone. Kumane kuyizindawo lapho ukugxila kwe-ozone kungaphansi kakhulu kokujwayelekile. Lokhu kuhlushwa kuphansi ngokwanele ukungavumeli imisebe ye-ultraviolet ukuthi ihlale endaweni 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 nezinye izivumelwano zomhlaba wonke zahlanganiswa ezibanga noma zokuvinjelwa kwalawa makhemikhali, ngoba nazo zisebenza njengamagesi abamba ukushisa.
Njengoba ukwazi ukubona, ama-chlorofluorocarbon anemiphumela emibi emikhulu emkhathini, kanye nasezilwaneni, ezitshalweni nakubantu. Ngiyethemba ukuthi ngalolu lwazi ungafunda kabanzi ngama-chlorofluorocarbon.