Kungani Ulwandle Lunosawoti?

UKUBE wonke usawoti osolwandle ubungandlalwa ezweni ngokulinganayo, ubungaba ugqinsi olungaphezu kwamamitha angu-150—ubungalingana nezitezi ezicishe zibe ngu-45! Uvelaphi wonke lo sawoti, ikakhulu uma ucabangela ukuthi kunemisele nemifula eminingi enamanzi angenawo usawoti egelezela olwandle? Ososayensi baye bathola imithombo eminingana.

Omunye umthombo inhlabathi esihamba kuyo. Njengoba amanzi emvula engena enhlabathini nasemifantwini yamadwala, ancibilikisa izinhlayiyana ezithile zamaminerali, kuhlanganise nosawoti kanye nengxube yawo, bese ekudlulisela olwandle ngemisele nemifula (1). Nokho, isilinganiso sikasawoti emanzini asemachibini nasemifuleni sincane kakhulu, yingakho singawuzwa.

Omunye umthombo amaminerali akha usawoti asongqimbeni lomhlaba olungaphansi kolwandle. Amanzi angena emifantwini yolwandle, ashise kakhulu, abese ekhuphukela phezulu namaminerali ancibilikile. Imifantu ekhipha amanzi ashisayo—eminye esekujuleni kolwandle—ikhiphela le nhlanganisela yamakhemikhali olwandle (2).

Kwenye inqubo enomphumela ofanayo, izintaba-mlilo ezisekujuleni kolwandle zikhiphela indathane yamadwala ashisayo olwandle, lapho la madwala ekhipha khona amakhemikhali bese ewafaka emanzini (3). Omunye umthombo wamaminerali umoya, othatha izinhlayiyana zamaminerali ezweni uziyise olwandle (4). Zonke lezi zinqubo zenza amanzi asolwandle abe ingxube cishe yawo wonke amakhemikhali aziwayo. Nokho, ingxenye enkulu yalo sawoti i-sodium chloride—usawoti ovamile. Wakha amaphesenti angu-85 kasawoti oncibilikile futhi yiwona ikakhulu owenza amanzi asolwandle abe nosawoti.

Yini Eyenza Amazinga Kasawoti Angaguquguquki?

Ulwandle lunosawoti omningi ngenxa yokuthi amanzi ahwamuka olwandle ahlanzeké cishe ngokuphelele. Kusala amaminerali kuphela. Ngesikhathi esifanayo, kunamaminerali engeziwe aqhubeka engena olwandle; kodwa, izinga likasawoti lihlala lisesilinganisweni esingaba izingxenye zikasawoti ezingu-35 kweziyinkulungwane zamanzi. Kusobala-ke ukuthi kunezelwa futhi kukhishwe usawoti namanye amaminerali cishe ngezinga elifanayo. Lokhu kwenza sibuze, Uyaphi lo sawoti?

Izinhlobo eziningi zikasawoti zimuncwa yimizimba yezinto eziphilayo. Ngokwesibonelo, ama-coral polyp, ama-mollusk nama-crustacean amunca i-calcium, eyisakhi sikasawoti, ukuze akhe amagobolondo namathambo. Ulwelwe olungabonakali okuthiwa ama-diatom lumunca i-silica. Ama-bacterium nezinye izinto zimunca izinto eziphuma ezintweni eziphilayo. Lapho lezi zinto zifa noma zidliwa, usawoti namaminerali asemizimbeni yazo agcina esekujuleni kolwandle efile noma eyindle (5).

Usawoti omningi ongamunceki ngendlela engokwemvelo ukhishwa ngezinye izindlela. Ngokwesibonelo, ubumba nezinye izinto eziyinhlabathi ezingena olwandle ngemifula, ngokuguguleka kwenhlabathi nangodaka lwezintaba-mlilo zingase zinamathele ezinhlotsheni ezithile zikasawoti zehlele nazo ekujuleni kolwandle. Omunye usawoti unamathela nasemadwaleni. Ngakho, ngezinqubo ezihlukahlukene, omningi walo sawoti ugcina usuyingxenye yesihlabathi esisekujuleni kolwandle (6).

Abacwaningi abaningi bakholelwa ukuthi lo mjikelezo upheleliswa yizinqubo ezenzeka emhlabeni, nakuba lokhu kuthatha isikhathi eside kakhulu. Umhlaba unezingqimba ezinkulu. Ezinye zithi uma zihlangana, olunye lungene ngaphansi kolunye, lugcine lusemathunjini omhlaba ashisayo. Ngokuvamile ungqimba olusindayo olusolwandle lungena ngaphansi kongqimba olulula lwenhlabathi, ngesikhathi esifanayo lwehla nenzika enosawoti. Ngale ndlela kancane kancane ingxenye enkulu yongqimba lomhlaba iyashintsha (7). Ukuzamazama komhlaba, izintaba-mlilo nemifantu emikhulu ebusweni bomhlaba kuyimiphumela emithathu yalezi zinqubo.a

Ukungaguquguquki Okumangalisayo

Usawoti osolwandle uyahlukahluka kuye ngezindawo, futhi ngezinye izikhathi nangenkathi yonyaka. Amanzi anosawoti omningi kunawo wonke asePersian Gulf nasoLwandle Olubomvu, lapho amanzi ehwamuka khona ngezinga eliphakeme kakhulu. Izindawo ezisolwandle ezithola amanzi asuka emifuleni emikhulu noma ezithola imvula eningi azinawo usawoti omningi njengokuvamile. Kunjalo nangamanzi olwandle aseduze kwezindawo ezineqhwa elincibilikayo enyakatho naseningizimu, iqhwa elakhiwa amanzi angenasawoti. Ngakolunye uhlangothi, lapho kuba neqhwa, amanzi olwandle aseduze aba nosawoti omningi. Nokho, okuphawulekayo ukuthi ulwandle luvame ukuba nezinga likasawoti elingaguquguquki.

Amanzi olwandle anezinga elingaguquguquki le-pH, okuyisilinganiso sokuthi into ine-asidi noma ayinayo, kanti engenayo i-asidi inesilinganiso esingu-7. Amanzi olwandle ane-pH ephakathi kuka-7,4 no-8,3, ngakho awana-asidi. (Igazi lomuntu line-pH engaba ngu-7,4.) Uma i-pH ibingadlula kuleli zinga, ulwandle beluyoba senkingeni enkulu. Empeleni, yilokho ososayensi abaningi abakwesabayo manje. Isikhutha esiningi abantu abasikhiphela emkhathini siphelela olwandle, lapho sixubana khona namanzi sibe i-carbonic acid. Ngakho kungenzeka ukuthi kancane kancane izenzo zomuntu zenza ulwandle lube i-asidi.

Eziningi zezinqubo ezigcina amanzi olwandle enamakhemikhali asezingeni elingaguquguquki aziqondwa ngokuphelele. Noma kunjalo, lokho esikufundile kugcizelela ukuhlakanipha okukhulu koMdali, owukhathalelayo umsebenzi wezandla zakhe.—IsAmbulo 11:18.

[Umbhalo waphansi]

[Umdwebo/Izithombe ekhasini 16, 17]

(Ukuze ubone ukuthi indaba ihlelwe kanjani, bheka encwadini)

Imvula

↓↓

↓↓

4 Umoya

↑ ↓ ↓

․․․․․․․․․․↑․․․․․․․․․․․․↑․․․KOLWANDLE․․․↓․․․․․ ․․․․↓․․․

↑ ↑ 7 ←← UKUHLANGANA

↑ UNGQIMBA LOMHLABA ←← KWEZINGQIMBA

↑ ←←

․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․

[Imithombo]

Vent: © Science VU/Visuals Unlimited; eruption: REUTERS/Japan Coast Guard/Handout

Diatoms: Dr. Neil Sullivan, USC/NOAA Corps; volcano photo: Dept. of Interior, National Park Service

[Ibhokisi/Umdwebo ekhasini 18]

Izinhlobo Zikasa-woti Ezitholakala Olwandle

Nakuba sekuyiminyaka engaphezu kwekhulu ososayensi behlola amanzi olwandle, abakayazi ngokuphelele ingxube yawo yamakhemikhali. Nokho, baye bakwazi ukuthola izinhlobo ezihlukahlukene zikasawoti ezincibilikile futhi babala isilinganiso sazo kula manzi. Lezi zinhlobo zikasawoti zihlanganisa nalezi ezilandelayo:

[Umdwebo]

55% Chloride

30,6 Sodium

7,7 Sulfate

3,7 Magnesium

1,2 Calcium

1,1 Potassium

0,4 Bicarbonate

0,2 Bromide

kanye nezinye ezini-ngana, njenge-borate, i-strontium ne-fluoride.

[Ibhokisi/Isithombe ekhasini 18]

Anosawoti Omningi Kunawasolwandle

Amanye amachibi anamanzi anosawoti omningi kunawasolwandle. Isibonelo esiyinhloko salokhu uLwandle Olufile, olunamanzi anosawoti omningi kunawo wonke emhlabeni. Amanzi agelezela oLwandle Olufile, olwalubizwa ngokuthi uLwandle Lukasawoti ngezikhathi zeBhayibheli, anosawoti oncibilikile namanye amaminerali. (Numeri 34:3, 12) Ngenxa yokuthi usebe loLwandle Olufile luyindawo eyomile ephansi kunazo zonke emhlabeni, yinye kuphela indlela amanzi angaphuma ngayo—ngokuhwamuka, okunganciphisa isilinganiso samanzi kulolu lwandle ngamamilimitha angaba ngu-25 ngosuku ngesikhathi sasehlobo.

Ngenxa yalokho, amanzi angaphezulu aqukethe usawoti ongaba amaphesenti angu-30—ophindwe cishe kayishumi kunosawoti wasoLwandle iMediterranean. Ngenxa yokuthi amanzi ayajiya uma egcwele usawoti, ababhukudi bayakwazi ukuntanta phezulu kula manzi. Empeleni, bangaqethuka nje bafunde iphephandaba emanzini kungenalutho lokuntanta abalele phezu kwalo.

[Ibhokisi ekhasini 18]

Usawoti Uyasiza Ekuhlanzeni Umoya

Ucwaningo luye lwabonisa ukuthi izinhlayiya zokungcola ezisemoyeni zinciphisa imvula esemafwini ahamba phezu kwezwe. Nokho, amafu anokungcola ahamba phezu kolwandle enza imvula kalula. Lo mehluko kuthiwa ubangelwa umhwamuko onosawoti wasolwandle, ovela emanzini.

Amaconsi amanzi abamba izinhlayiya zokungcola emkhathini avame ukuba mancane kakhulu ukuba angaba imvula; ngakho, antanta nje emoyeni. Umhwamuko onosawoti wasolwandle unezela isisindo emafwini ahamba phezu kolwandle ngokudonsa la maconsi amancane uwenze abe makhulu. Umphumela kuba imvula, esiza nasekuhlanzeni ukungcola emkhathini.