{"id":181,"date":"2017-09-17T17:31:02","date_gmt":"2017-09-17T17:31:02","guid":{"rendered":"http:\/\/80.85.86.254\/sjor\/?p=181"},"modified":"2024-10-15T16:12:19","modified_gmt":"2024-10-15T16:12:19","slug":"1-5-efni-sjavar","status":"publish","type":"post","link":"https:\/\/himinnoghaf.is\/mengunsjavar\/index.php\/2017\/09\/17\/1-5-efni-sjavar\/","title":{"rendered":"1.5 Efni sj\u00e1var"},"content":{"rendered":"

Einn af eiginleikum vatns er a\u00f0 leysa upp \u00f6nnur efni, s.s. s\u00f6lt og steinefni. \u00cd sj\u00f3num m\u00e1 finna gr\u00ed\u00f0armikinn fj\u00f6lda efna og efnasambanda en magn \u00feeirra og dreifing er afar mismunandi. Efnum sj\u00e1var m\u00e1 skipta \u00ed 5 a\u00f0alflokka: s\u00f6lt, n\u00e6ringars\u00f6lt, uppleystar lofttegundir, snefilefni og efni \u00ed sviflausn. Kolefniskerfi sj\u00e1var gegnir mikilv\u00e6gu hlutverki vi\u00f0 a\u00f0 vinna gegn breytingum \u00e1 s\u00fdrustigi.<\/p>\n

<\/span>S\u00f6lt. <\/em>Me\u00f0alselta sj\u00e1var er 35\u2030\u00a0sem \u00fe\u00fd\u00f0ir a\u00f0 \u00ed 1000 kg af sj\u00f3 eru 35 kg af s\u00f6ltum. Mikilv\u00e6gast er natr\u00edumkl\u00f3r\u00ed\u00f0 (NaCl) en rekja m\u00e1 yfir 99% af \u00f6llum s\u00f6ltum \u00ed sj\u00f3num til a\u00f0eins sex j\u00f3na<\/span> (tafla 1.1). Styrkur \u00feessara saltj\u00f3na er tilt\u00f6lulega jafn b\u00e6\u00f0i milli hafsv\u00e6\u00f0a og me\u00f0 d\u00fdpt. Breytingar \u00e1 styrk m\u00e1 n\u00e6r eing\u00f6ngu rekja til \u00farkomu og uppgufunar vatns.\u00a0\u00c1 opnu hafi er styrkur \u00feessara saltj\u00f3na hverrar um sig meiri en 1 mg\/kg. \u00deessar j\u00f3nir eiga \u00fea\u00f0 sameiginlegt a\u00f0 t\u00edminn sem \u00fea\u00f0 tekur a\u00f0 b\u00e6ta jafnmiklu magni af j\u00f3nunum \u00ed sj\u00f3inn og er \u00fear a\u00f0 finna, er gr\u00ed\u00f0arlega langur – mun lengri en uppbl\u00f6ndunart\u00edmi sj\u00e1var, sem er um 1000 \u00e1r. Me\u00f0 \u00f6\u00f0rum or\u00f0um m\u00e1 segja a\u00f0 uppsprettur og svelgir<\/span> \u00feessara efna s\u00e9u l\u00edtilvirkir mi\u00f0a\u00f0 vi\u00f0 magn efnanna \u00ed sj\u00f3num og hafi \u00fev\u00ed l\u00edtil \u00e1hrif \u00e1 styrk \u00feeirra.<\/p>\nTafla 1.1. Sj\u00e1vars\u00f6lt: Tegundir j\u00f3na og \u00feyngdarhlutf\u00f6ll<\/span>\n\n\n\n\n\t\n\n\t\n\t\n\t\n\t\n\t\n\t
J\u00f3n<\/th>\u00deyngd \u00ed sj\u00f3<\/th>\n<\/tr>\n<\/thead>\n
Kl\u00f3r (Cl-<\/sup>)<\/td>55,1%<\/td>\n<\/tr>\n
Natr\u00edum (Na+<\/sup>)<\/td>30,6%<\/td>\n<\/tr>\n
S\u00falfat (SO4<\/sub>2-<\/sup>)<\/td>7,7%<\/td>\n<\/tr>\n
Magnes\u00edum (Mg2+<\/sup>)<\/td>3,7%<\/td>\n<\/tr>\n
Kals\u00edum (Ca2+<\/sup>)<\/td>1,2%<\/td>\n<\/tr>\n
Kal\u00edum (K+<\/sup>)<\/td>1,1%<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n

<\/span>N\u00e6ringars\u00f6lt<\/em> sj\u00e1var eru a\u00f0 langmestu leyti k\u00f6fnunarefni (N) og fosf\u00f3r (P) \u00e1 j\u00f3naformi. \u00deau eru nau\u00f0synleg \u00f6llum sj\u00e1varpl\u00f6ntum til vaxtar og vi\u00f0gangs. K\u00edsill (Si) er ekki n\u00e6ringarefni \u00ed sama skilningi en er nau\u00f0synlegur sumum tegundum l\u00edfvera. Hann er \u00fev\u00ed l\u00edka talinn me\u00f0 n\u00e6ringars\u00f6ltum. Styrkur \u00feessara efna er mj\u00f6g breytilegur \u00ed hafinu og oftast langt undir 1 mg\/kg. \u00deessi efni eru \u00fea\u00f0 sem kalla\u00f0 er l\u00edfhverful<\/span>, sem \u00fe\u00fd\u00f0ir a\u00f0 \u00feau geta ey\u00f0st \u00ed yfirbor\u00f0sl\u00f6gum sj\u00e1var af v\u00f6ldum l\u00edfvera. \u00de\u00e1 getur gr\u00f3\u00f0urv\u00f6xtur n\u00e1nast st\u00f6\u00f0vast.<\/p>\n

<\/span>Uppleystar lofttegundir<\/em> \u00ed sj\u00f3 eru b\u00e6\u00f0i lofttegundir sem algengar eru \u00ed lofthj\u00fapnum eins og k\u00f6fnunarefni, s\u00farefni, kold\u00edox\u00ed\u00f0 og argon og \u00f3algengar lofttegundir. Allar lofttegundir andr\u00famsloftsins finnast uppleystar \u00ed hafinu. Hlutf\u00f6llin eru \u00fe\u00f3 talsvert \u00f3l\u00edk \u00fev\u00ed sem gerist \u00ed andr\u00famsloftinu. Til a\u00f0 mynda er hlutfallslega meira af b\u00e6\u00f0i s\u00farefni og kold\u00edox\u00ed\u00f0i \u00ed sj\u00f3 en \u00ed andr\u00famsloftinu en minna er af k\u00f6fnunarefni, sj\u00e1 t\u00f6flu 1.2.<\/p>\nTafla 1.2. Hlutfall helstu lofttegunda \u00ed andr\u00famslofti og jafnv\u00e6gisstyrkur \u00ed sj\u00f3 (selta 35\u2030, 20\u00b0C).<\/span>\n\n\n\n\n\t\n\n\t\n\t\n\t\n\t
Lofttegund<\/th>Hlutfall \u00ed andr\u00famslofti<\/th>Jafnv\u00e6gisstyrkur \u00ed sj\u00f3 <\/th>\n<\/tr>\n<\/thead>\n
K\u00f6fnunarefni (N2<\/sub>)<\/td>78,1%<\/td>418 (\u00b5mol\/kg)<\/td>\n<\/tr>\n
S\u00farefni (O2<\/sub>)<\/td>21,0%<\/td>225 (\u00b5mol\/kg)<\/td>\n<\/tr>\n
Argon (Ar)<\/td>0,9%<\/td>11,0 (\u00b5mol\/kg)<\/td>\n<\/tr>\n
Kold\u00edox\u00ed\u00f0 (CO2<\/sub>)<\/td>0,04%<\/td>11,6 (\u00b5mol\/kg)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n

Leysni lofttegunda \u00ed hafinu er h\u00e1\u00f0 seltu og hitastigi. Lofttegundir leysast best upp \u00ed k\u00f6ldum og l\u00edti\u00f0 s\u00f6ltum sj\u00f3, en \u00feegar selta og hitastig h\u00e6kka, l\u00e6kkar styrkur uppleystra lofttegunda. S\u00farefni er s\u00fa lofttegund sem mest hefur veri\u00f0 ranns\u00f6ku\u00f0 \u00ed hafinu. Styrkur s\u00farefnis er mj\u00f6g breytilegur og geta m\u00e6lingar \u00e1 s\u00farefni veitt margs konar uppl\u00fdsingar um uppruna sj\u00e1var og endurn\u00fdjun, l\u00edfsstarfsemina \u00ed efstu sj\u00e1varl\u00f6gum sem og ni\u00f0urbrot og oxun l\u00edfr\u00e6nna efna \u00ed dj\u00fapl\u00f6gum. \u00cd yfirbor\u00f0sl\u00f6gum fer styrkur s\u00farefnis eftir hitastigi og er \u00fev\u00ed breytilegur eftir \u00e1rst\u00edma \u00e1 sv\u00e6\u00f0um utan hitabeltisins. S\u00farefni myndast vi\u00f0 lj\u00f3still\u00edfun og ey\u00f0ist vi\u00f0 \u00f6ndun og sundrun l\u00edfr\u00e6nna efna. \u00deessi tv\u00f6 gagnst\u00e6\u00f0u ferli (lj\u00f3still\u00edfun og \u00f6ndun\/sundrun) eru a\u00f0alors\u00f6k sta\u00f0bundinna breytinga \u00e1 s\u00farefni \u00ed hafinu. \u00cd lj\u00f3sn\u00e6ma laginu getur lj\u00f3still\u00edfun valdi\u00f0 talsver\u00f0ri yfirmettun s\u00farefnis. \u00c1 \u00f6llum d\u00fdptum ey\u00f0ist s\u00farefni vegna \u00f6ndunar d\u00fdra, plantna og \u00f6rvera sem og vegna oxunar \u00e1 l\u00edfr\u00e6num leifum. \u00c1 opnu hafi sj\u00e1 l\u00e1r\u00e9ttir og l\u00f3\u00f0r\u00e9ttir straumar og bl\u00f6ndun vegna \u00f3reglulegra, tilviljanakenndra hreyfinga sj\u00e1var til \u00feess a\u00f0 s\u00farefnisfor\u00f0ab\u00fari\u00f0 t\u00e6mist ekki. \u00c1 inniloku\u00f0um hafsv\u00e6\u00f0um, s.s. \u00ed Svartahafi og \u00ed \u00fer\u00f6skuldsfj\u00f6r\u00f0um<\/span>, getur s\u00farefnisfor\u00f0inn kl\u00e1rast algerlega \u00ed ne\u00f0ri sj\u00e1varl\u00f6gum. \u00de\u00e1 getur ni\u00f0urbrot (sundrun) l\u00edfr\u00e6nna efna or\u00f0i\u00f0\u00a0loftfirrt<\/span> og eitra\u00f0ar lofttegundir eins og ammon\u00edak og brennisteinsvetni myndast. Sl\u00edkt getur einnig gerst vegna mengunar (sj\u00e1 kafla 5.2<\/a>).<\/p>\n

<\/span>Snefilefni<\/em> eru efni sem er a\u00f0 finna \u00ed \u00f6rlitlu magni \u00ed sj\u00f3num. Um er a\u00f0 r\u00e6\u00f0a \u00fdmsa m\u00e1lma og l\u00edfr\u00e6n efnasamb\u00f6nd. Snefilm\u00e1lmarnir geta veri\u00f0 \u00e1 formi einfaldra j\u00f3na, j\u00f3napara, samsettra efnasambanda e\u00f0a sem hringsamb\u00f6nd m\u00e1lma og l\u00edfr\u00e6nna efna. Uppleyst l\u00edfr\u00e6n efni \u00ed hafinu ver\u00f0a a\u00f0allega til vi\u00f0 ni\u00f0urbrot fastra l\u00edfr\u00e6nna efna \u00ed sj\u00f3num, en geta einnig veri\u00f0 upprunnin \u00e1 landi. Sum \u00feessara efna eru tilkomin vegna mannlegra athafna og me\u00f0al \u00feeirra eru fj\u00f6lm\u00f6rg algeng mengunarefni. Styrkur snefilefna er yfirleitt langt undir 1 mg\/kg.<\/p>\n

<\/span>Efni \u00ed sviflausn<\/em> eru f\u00f6st efni sem sv\u00edfa um \u00ed sj\u00f3num e\u00f0a mynda grugg. St\u00e6r\u00f0 agnanna er mj\u00f6g breytileg, e\u00f0a allt fr\u00e1 \u00fev\u00ed a\u00f0 vera meira en 1 mm \u00ed \u00feverm\u00e1l, ni\u00f0ur \u00ed a\u00f0 vera 0,1-10 \u00b5m. \u00deessi efni finnast alls sta\u00f0ar \u00ed hafinu en eru mest \u00e1berandi \u00e1 strandsv\u00e6\u00f0um og vi\u00f0 \u00e1r\u00f3sa.<\/p>\n

<\/span>Kolefniskerfi sj\u00e1var<\/strong><\/em><\/h6>\n

Kolefniskerfi sj\u00e1var gefur sj\u00f3num allmikla \u201ed\u00faah\u00e6fni\u201c<\/span>, e\u00f0a \u201ebuffer-eiginleika\u201c eins og \u00fea\u00f0 er stundum kalla\u00f0, \u00fe.e.a.s. kerfi\u00f0 vinnur gegn breytingum \u00e1 s\u00fdrustigi sj\u00e1var. S\u00e1 eiginleiki er mj\u00f6g mikilv\u00e6gur fyrir \u00fdmsar l\u00edfverur \u00ed hafinu sem eru n\u00e6mar fyrir jafnvel sm\u00e1v\u00e6gilegum breytingum \u00e1 s\u00fdrustigi.<\/p>\n

Kolefni er a\u00f0 finna \u00ed sj\u00f3num sem kold\u00edox\u00ed\u00f0 (CO2<\/sub>), kols\u00fdra (H2<\/sub>CO3<\/sub>), b\u00edkarb\u00f3nat (HCO3<\/sub>–<\/sup>) og karb\u00f3nat (CO3<\/sub>2-<\/sup>). \u00deessi mismunandi form kolefnis eru \u00ed jafnv\u00e6gi hvert vi\u00f0 anna\u00f0 og vi\u00f0 vetnisj\u00f3nir (H+<\/sup>) \u00ed sj\u00f3num. Langst\u00e6rstan hluta kolefnisins er a\u00f0 finna sem karb\u00f3nat og b\u00edkarb\u00f3nat. L\u00edffr\u00e6\u00f0ilegir ferlar, s.s. lj\u00f3still\u00edfun (tekur upp kold\u00edox\u00ed\u00f0) og \u00f6ndun (gefur fr\u00e1 s\u00e9r kold\u00edox\u00ed\u00f0), leika st\u00f3rt hlutverk var\u00f0andi breytingar \u00e1 magni kold\u00edox\u00ed\u00f0s \u00ed sj\u00f3. \u00deegar kold\u00edox\u00ed\u00f0 leysist upp \u00ed sj\u00f3num hvarfast \u00fea\u00f0 vi\u00f0 vatn og myndar kols\u00fdru:<\/p>\n

CO2<\/sub>(g) \u2194 CO2<\/sub>(aq) (uppleysing)<\/p>\n

CO2<\/sub>(aq) + H2<\/sub>O \u2194 H2<\/sub>CO3\u00a0<\/sub>(myndun kols\u00fdru)<\/p>\n

Kols\u00fdran brotnar mj\u00f6g hratt ni\u00f0ur \u00ed vetnisj\u00f3nir\u00a0(H+<\/sup>) og b\u00edkarb\u00f3nat (HCO3<\/sub>–<\/sup>).<\/p>\n

H2<\/sub>CO3<\/sub> \u2194 HCO3<\/sub>–<\/sup> + H+<\/sup><\/p>\n

B\u00edkarb\u00f3nat getur brotna\u00f0 frekar ni\u00f0ur \u00ed karb\u00f3nat og vetnisj\u00f3n.<\/p>\n

HCO3<\/sub>–<\/sup> \u2194 CO3<\/sub>2-<\/sup> + H+<\/sup><\/p>\n

Karb\u00f3nat gengur svo \u00ed samband vi\u00f0 kals\u00edum og myndar kalk (kals\u00edumkarb\u00f3nat).<\/p>\n

Ca2+<\/sup> + CO3<\/sub>2-<\/sup> \u2194 CaCO3<\/sub><\/p>\n

Efnahv\u00f6rfin geta gengi\u00f0 \u00ed b\u00e1\u00f0ar \u00e1ttir \u2013 \u00feess vegna eru \u00f6rvarnar (\u2194) \u00ed b\u00e1\u00f0ar \u00e1ttir. \u00deau eru drifin \u00e1fram af breytingum \u00ed styrk kold\u00edox\u00ed\u00f0s \u00ed sj\u00f3num en s\u00fdrustig, hitastig, selta og basavirkni hafa einnig \u00e1hrif. N\u00e1nar ver\u00f0ur fjalla\u00f0 um \u00e1hrif losunar kold\u00edox\u00ed\u00f0s \u00e1 kolefniskerfi sj\u00e1var \u00ed kafla 3.6<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Einn af eiginleikum vatns er a\u00f0 leysa upp \u00f6nnur efni, s.s. s\u00f6lt og steinefni. \u00cd sj\u00f3num m\u00e1 finna gr\u00ed\u00f0armikinn fj\u00f6lda efna og efnasambanda en magn \u00feeirra og dreifing er afar mismunandi. Efnum sj\u00e1var m\u00e1 skipta \u00ed 5 a\u00f0alflokka: s\u00f6lt, n\u00e6ringars\u00f6lt, Lesa meira…<\/a><\/p>\n","protected":false},"author":2,"featured_media":1000,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[],"class_list":["post-181","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-01-umsjoinn"],"_links":{"self":[{"href":"https:\/\/himinnoghaf.is\/mengunsjavar\/index.php\/wp-json\/wp\/v2\/posts\/181","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/himinnoghaf.is\/mengunsjavar\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/himinnoghaf.is\/mengunsjavar\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/himinnoghaf.is\/mengunsjavar\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/himinnoghaf.is\/mengunsjavar\/index.php\/wp-json\/wp\/v2\/comments?post=181"}],"version-history":[{"count":63,"href":"https:\/\/himinnoghaf.is\/mengunsjavar\/index.php\/wp-json\/wp\/v2\/posts\/181\/revisions"}],"predecessor-version":[{"id":3964,"href":"https:\/\/himinnoghaf.is\/mengunsjavar\/index.php\/wp-json\/wp\/v2\/posts\/181\/revisions\/3964"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/himinnoghaf.is\/mengunsjavar\/index.php\/wp-json\/wp\/v2\/media\/1000"}],"wp:attachment":[{"href":"https:\/\/himinnoghaf.is\/mengunsjavar\/index.php\/wp-json\/wp\/v2\/media?parent=181"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/himinnoghaf.is\/mengunsjavar\/index.php\/wp-json\/wp\/v2\/categories?post=181"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/himinnoghaf.is\/mengunsjavar\/index.php\/wp-json\/wp\/v2\/tags?post=181"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}