Ngokuqinisekileyo xa usiva malunga nomngxunya oselalini yeozone obalwa ziigesi eziwongameleyo. Eyona nto iphambili kwimichiza ebangele ukwehla koxinaniso lweozone yomoya iklorofluorocarbons. Ezi ziikhemikhali zerhasi ezazisetyenziswa ukusukela oko zaqalwa ngo-1928. Ziyaziwa nesifinyezo esithi CFC. Baye baphandwa ngokweenkcukacha kwaye babonisa ukuba iipropathi zabo zisengozini kungekuphela kwimpilo yoluntu kodwa nakwe-ozone layer. Ke ngoko, ukusetyenziswa kwayo bekungavumelekanga.
Kule nqaku siza kukuxelela ukuba ziyintoni i-chlorofluorocarbons, ziyintoni iimpawu zazo kwaye kutheni zitshabalalisa ungqimba lwe-ozone.
Yintoni i-chlorofluorocarbons?
Ezi ziikhemikhali ezenziwe ngekhabhon, i-fluorine, kunye neeathom zeklorine. Kungoko igama layo. Ezi athom zeqela le ii-halocarbons eziliqela leegesi azinetyhefu okanye zinokutsha. Zavela okokuqala ngo-1928 njengenye indlela eyahlukileyo kwimichiza eyayisetyenziswa kwizikhenkcisi. Kamva zisetyenziselwa ukuhambisa izinto zokubulala izinambuzane, ipeyinti, izinto zokulungisa iinwele kunye nezinye iimveliso zokhathalelo lwempilo.
Phakathi kweminyaka yama-50 ukuya kuma-60s zazisetyenziselwa ukufomatha amakhaya, iimoto kunye neeofisi. Zonke ezi zinto zisetyenzisiweyo zibangele ukuba i-chlorofluorocarbons yandise kwihlabathi jikelele. Ngelo xesha ukusetyenziswa kwezi khemikhali kunyuke malunga nesigidi seetoni eziveliswa minyaka le ukusuka eUnited States. Emva kwexesha inyuse ukusetyenziswa kwayo nangakumbi. Ifikelele kwinqanaba lokuba isetyenziswe njenge i-aerosol, ifriji, iarhente yokuvuthela amagwebu, izinto zokupakisha kunye nezinyibilikisi.
Uninzi lweemveliso zechlorofluorocarbon
Ezi khemikhali azinawo umthombo wendalo ovela kuzo. Ziikhemikhali ezenziwe ngabantu kusetyenziso oluninzi. Zazisetyenziswa njengezikhenkcezisi, izinto eziphumisayo kunye nezinyibilikisi zoshishino zokwenza amagwebu. Ikwasebenza njengearhente yokucoca ekwenziweni kweemveliso zombane. Ukusetyenziswa kwayo kube nefuthe kubume be-ozone obonyuke kakhulu ngexesha elifutshane. Ezi gesi zaziwa ngokutshabalalisa i-ozone ye-stratospheric ukuya kuthi ga kwinqanaba lokuba imitha yelanga eyingozi yelanga ifikelele ngaphezulu.
Phakathi kweemveliso ezithandwa kakhulu yi-chlorofluorocarbon kwezi zilandelayo:
- Isikhenkcisi sikwimeko zokupholisa umoya.
- Iifriji.
- Iipropellants kwii-aerosol.
- I-inhalers yokulawula isifuba. Emva kwexesha oku kwavalwa ukunciphisa ifuthe kwi-stratosphere.
- IHaloalkanes kwiinqwelomoya.
- Izinyibilikisi zifuna igrisi kwakamsinya.
Iziphumo ezibi zechlorofluorocarbons emoyeni
Njengoko bekutshiwo ngaphambili, ezi khemikhali bezisaziwa ngokonakalisa umaleko weozone. Oku kuthetha ukuba uninzi lwemitha yelanga ephuma elangeni inokudlula kwi-stratosphere ize ifikelele kumphezulu womhlaba. Kubonwe ukuba neziphumo ezibi ezininzi kwimpilo yethu. Kwaye kungenxa yokuba, njengoko zizinto ezahlukeneyo ezingena khemikhali, bekucingelwa ukuba azinakuba yingozi emoyeni. Nangona kunjalo, ngokuhamba kwexesha kwafumaniseka ukuba Isabele ngemitha yelanga esibhakabhakeni, ngakumbi kwi-stratosphere.
Kule ngqimba yeatmosfera kukho uxinizelelo olukhulu lweozone olusinceda ukunciphisa imitha yelanga ephuma elangeni. Olu xinzelelo lukhulu lwe-ozone yaziwa ngokuba ngumaleko we-ozone. Xa i-chlorofluorocarbons inxibelelana nemitha ye-radiation ifumana ukubola kwe-photolytic esijika sibe yimithombo ye-chlorine engaphiliyo. Xa i-chlorine ikhutshwa ngohlobo lwee-atom bayakwazi ukuguqula ukuguqulwa kweemolekyuli ze-ozone kwioksijini. Oku kuthetha ukuba ikhawulezisa ukusabela ngokwendalo kweekhemikhali yokuguqula i-ozone ibe yioksijini.
Siyakhumbula ukuba imolekyuli yeozone yenziwe ziiathom zeoksijini ezi-3. Ioksijini yomoya yenziwa ziiathom ezimbini zeoksijini. Ngale ndlela, i-chlorine isebenza njengesixhobo sokunyusa izinga kunye nobungakanani bokusabela kweekhemikhali eziguqula i-ozone ibe yioksijini. Ngaloo ndlela ukuya kuthi ga kwi-100.000 iimolekyuli ze-ozone ezinokutshatyalaliswa kwi-athomu nganye yeklorin ekhutshiweyo. Zonke ezi zizathu zokuba kutheni ii-chlorofluorocarbons zinxulumene nokutshatyalaliswa kocwecwe lwe-ozone.
Ayisiyokuba ezi khemikhali zitshabalalise ngokuthe ngqo i-ozone efumaneka kwi-stratosphere, kodwa endaweni yokuba iindlela ezahlukeneyo zekhemikhali ziyafuneka ukuze zenzeke. Nangona kunjalo, isantya apho i-chlorofluorocarbons iya kukhutshelwa kwiatmosfera yabangela ukuba isixa esikhulu se-ozone estratospheric sinyamalale. Ukunyamalala kocwecwe lwe-ozone kunemiphumo eyonakalisayo kwaye kukonyusa ukungcoliseka kweekhemikhali. Kwaye i-ozone inoxanduva ukufunxa ubuninzi bemitha yelanga phakathi kwe-wavelengths ye-280 kunye ne-320 nm kwaye iyingozi kwizilwanyana nakwizityalo nakubantu, kunjalo.
Umngxunya weozone
Ukusetyenziswa kwezi khemikhali kwinxalenye enkulu kukhokelele ekudalweni kwemingxunya kumaleko weozone. Ayikuko ukuba kukho umngxuma ngokwawo apho kungekho xinaniso lweozone. Ziindawo nje apho uxinzelelo lwe-ozone lungaphantsi kakhulu kunesiqhelo. Olu xinzelelo lusezantsi ngokwaneleyo ukuba lungavumeli imitha ye-ultraviolet ukuba ihlale kuloo ndawo kwaye ingene kumhlaba.
Nangona ii-chlorofluorocarbons zingavunyelwanga, ngenxa yokuba zinemichiza emikhulu kwaye azinyibiliki, nanamhlanje, uninzi lweekhemikhali ezikhutshwe kwiminyaka edlulileyo zisafumaneka. Kungenxa yokuba banobude bexesha lokuphila emoyeni. Ukususela ngo-1987 Umgaqo olandelwayo waseMontreal wazamkela ezi zinto zinobungozi kunye nezinye izivumelwano zamazwe aphesheya zaye zadityaniswa ezibangele okanye zokuthintelwa kwezi khemikhali, kuba zikwasebenza njengeegesi zegreenhouse.
Njengoko ubona, i-chlorofluorocarbons ineziphumo ezibi zombini emoyeni, nakwizilwanyana, kwizityalo nakubantu. Ndiyathemba ukuba olu lwazi ungafunda ngakumbi malunga neeklorofluorocarbon.