UMary Allen
Ulwandle luqulathe lwamanzi olwenziwe ngamanzi anetyuwa. Inxalenye enkulu yomhlaba igutyungelwe ngamanzi olwandle, ngaphezu kwesibini kwisithathu. Kukho iindawo ezizimeleyo, kodwa zonke zidibene. Oku kubizwa ngokuba “luLwandle lweHlabathi”. Idla ngokwahlulwa ibe ziilwandlekazi ezintlanu.
Ukongeza, iindawo zolwandle nazo zinamagama akhethekileyo, anje ngolwandle oludityanisiweyo kunye namatheku. Ulwandle lweMeditera ngumzekelo wale nto okanye iCaribbean. ULwandle Olubomvu phakathi kweYiputa neArabhiya lolona lwandle lusecaleni oluphantse lwavalwa ngokupheleleyo.
Umphezulu womhlaba ubukhulu becala ugutyungelwe ziilwandle: Umalunga nama-71 ekhulwini, oko kukuthi, phantse ikota yesithathu. Eyona ndawo inzulu iseMariana Trench kuLwandlekazi lwePasifiki. Kumalunga neshumi elinanye lamawaka eemitha ubunzulu apho.
Luyintoni kanye kanye ulwandle, yaye lubizwa ngokuba lulo?
Ukuba umzimba wamanzi ujikelezwe ngokupheleleyo ngumhlaba, awulolwandle kodwa lichibi. Amanye amachibi asabizwa ngokuba ziilwandle. Oku kunokuba nezizathu ezibini ezahlukeneyo.
ULwandle lweCaspian eneneni lichibi letyuwa. Oku kusebenza nakuLwandle oluFileyo. Zathiywa igama ngenxa yobukhulu bazo: ebantwini, zazibonakala ngathi zikhulu njengolwandle.
EJamani, kukho esinye isizathu esicacileyo. NgesiJamani, siqhele ukuthi Meer kwinxalenye yolwandle kwaye Bona ngokuma amanzi angaphakathi. NgesiJamani esisezantsi, nangona kunjalo, kungenye indlela. Oku kufumene indlela yayo kulwimi oluqhelekileyo lwesiJamani.
Yiyo loo nto sikwathi “ulwandle” lolwandle: uLwandle lwaseMntla, uLwandle lweBaltic, uLwandle oluMazantsi, njalo njalo. Kukwakho namachibi asemantla eJamani anegama elithi “ulwandle” kumagama awo. Elona chibi laziwa kakhulu yiSteinhuder Meer eLower Saxony, elona chibi likhulu emantla.
Zeziphi iilwandlekazi ezikhoyo?
Ulwandle lwehlabathi ludla ngokwahlulwa lube ziilwandlekazi ezintlanu. Olona Lwandlekazi lwePasifiki phakathi kweMelika neAsia. Ikwabizwa ngokuba yiPasifiki. Olwesibini ngobukhulu luLwandlekazi lweAtlantiki okanye uLwandlekazi lweAtlantiki phakathi kweYurophu neAfrika ukuya empuma kunye neMelika ngasentshona. Olwesithathu ngobukhulu luLwandlekazi lwaseIndiya phakathi kweAfrika, iIndiya neOstreliya.
Olwesine ngobukhulu luLwandlekazi lwaseMazantsi. Lo ngummandla ojikeleze ilizwe lase-Antarctica. Elona lincinane kwezintlanu luLwandle lweArctic. Ilele phantsi komkhenkce we-arctic kwaye ifikelela eKhanada naseRashiya.
Abanye abantu bathetha ngeelwandle ezisixhenxe. Ukongezelela kwiilwandlekazi ezintlanu, bongeza iilwandle ezimbini ezikufuphi kubo okanye abasoloko behamba ngenqanawa. Imizekelo eqhelekileyo luLwandle lweMeditera kunye neCaribbean.
Kumaxesha amandulo, abantu babebalwa neelwandle ezisixhenxe. Ezi yayiziinxalenye ezintandathu zeMeditera njengoLwandle lweAdriatic kunye noLwandle Olumnyama. Ixesha ngalinye linendlela yalo yokubala. Oku kwakunxulumene kakhulu nokuba zeziphi iilwandle ezaziwa kwaphela.
Kutheni iilwandle zibaluleke kangaka nje?
Abantu abaninzi bahlala ngaselwandle: babambisa iintlanzi apho, bamkele abakhenkethi okanye bahambe ngolwandle besiya kuthutha iimpahla. Ummandla wolwandle unemathiriyeli ekrwada efana ne-oyile ekrwada, ekhutshwayo.
Okokugqibela, ulwandle lubalulekile kwimozulu yesi sijikelezi-langa sethu uMhlaba. Iilwandle zigcina ubushushu, busasaze ngemisinga, kwaye zikwafunxa neegesi zegreenhouse ezifana nekharbon diokside. Ngoko ngaphandle kwabo, besiya kuba nobushushu obungakumbi behlabathi.
Nangona kunjalo, icarbon dioxide eninzi ayilunganga naselwandle. Emanzini olwandle, iba yi-carbonic acid. Oku kwenza iilwandle zibe neasidi, nto leyo engalunganga kumanzi amaninzi.
Iingcali ngemekobume zikwaxhalabile kukuba inkunkuma eninzi iphelela elwandle. Iplastiki ngokukodwa ithoba ngokucothayo. Nangona kunjalo, ibola ibe ngamaqhekeza amancinci, i-microplastics. Oku kuvumela ukuba iphelele kwimizimba yezilwanyana kwaye ibangele umonakalo apho.
Ingena njani ityuwa elwandle?
Akukho ndawo emhlabeni inamanzi amaninzi njengaselwandle: ama-97 ekhulwini. Nangona kunjalo, amanzi olwandle awaselwa. Kwamanye amanxweme, kukho izityalo zokukhupha ityuwa kumanzi olwandle, aze awajike abe ngamanzi okusela.
Iityuwa zifumaneka ematyeni ehlabathini lonke. Ngokunxulumene nolwandle, umntu udla ngokuthetha ngetyuwa yetafile okanye ityuwa eqhelekileyo, esiyisebenzisa ekhitshini. Ityuwa yetafile inyibilika kakuhle kakhulu emanzini. Kwanemali encinane ingena elwandle ngemilambo.
Kukho netyuwa phantsi kolwandle. Naleyo iyatshona ngokuthe chu emanzini. Iintaba-mlilo eziphantsi kolwandle nazo zinokukhupha ityuwa. Iinyikima eziselwandle nazo zibangela ukuba ityuwa ingene emanzini.
Umjikelo wamanzi ubangela ukuba amanzi amaninzi angene elwandle. Nangona kunjalo, inokulushiya ulwandle kwakhona ngenxa yokuba ngumphunga. Ityuwa ayihambi nayo. Ityiwa ithe yahlala elwandle. Okukhona amanzi eba ngumphunga, kokukhona ulwandle lusiba netyuwa eninzi. Ngoko ke, ubutyuwa abufani ncam kuzo zonke iilwandle.
Ilitha yamanzi olwandle idla ngokuqulatha malunga neegram ezingama-35 zetyuwa. Oko kumalunga necephe elifunjiweyo elinesiqingatha. Sidla ngokuzalisa malunga neelitha ezingama-150 zamanzi ebhafini. Ngoko kuya kufuneka ugalele malunga neekhilogram ezintlanu zetyuwa ukuze ufumane amanzi olwandle.