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<\/a>Mynd 3.16. Hnattr\u00e6n upps\u00f6fnun varma (\u00ed ZJ, \u00fe.e. 1021<\/sup>J) fr\u00e1 1961 til 2018.<\/p><\/div>\n Hl\u00fdnunin hef\u00f0i svo or\u00f0i\u00f0 enn meiri ef h\u00f6fin hef\u00f0u ekki dregi\u00f0 \u00ed sig um 25-30% af \u00fev\u00ed kold\u00edox\u00ed\u00f0i sem sett hefur veri\u00f0 \u00fat \u00ed andr\u00famslofti\u00f0. \u00deessi \u00fej\u00f3nusta hafanna er \u00fe\u00f3 d\u00fdru ver\u00f0i keypt! Sj\u00f3rinn er ekki bara a\u00f0 hl\u00fdna, hann er l\u00edka a\u00f0 s\u00farna.<\/strong> \u00deegar sj\u00f3r hl\u00fdnar eykst lagskipting sem aftur getur valdi\u00f0 s\u00farefnisskorti. \u00deessir \u00e1lags\u00fe\u00e6ttir (hl\u00fdnun, s\u00farnun og s\u00farefnisminnkun) hafa samverkandi og v\u00edxlverkandi \u00e1hrif. \u00deegar l\u00edfverur e\u00f0a vistkerfi eru \u00fatsett fyrir einum \u00e1lags\u00fe\u00e6tti (t.d. s\u00farnun) getur \u00feol \u00feeirra gagnvart \u00f6\u00f0rum \u00e1lags\u00fe\u00e1ttum minnka\u00f0. Loftslagsbreytingar, hl\u00fdnun sj\u00e1var og s\u00farnun sj\u00e1var hafa m.a. mikil \u00e1hrif \u00e1 k\u00f3ralrif.<\/p>\n Mynd 3.17. \u00c1hrif losunar gr\u00f3\u00f0urh\u00fasalofttegunda (GHL) og loftslagsbreytinga \u00e1 h\u00f6fin.<\/p><\/div>\n Mynd 3.17. s\u00fdnir \u00e1hrif losunar gr\u00f3\u00f0urh\u00fasalofttegunda og loftslagsbreytinga \u00e1 h\u00f6fin. Losun kold\u00edox\u00ed\u00f0s veldur s\u00farnun sj\u00e1var. S\u00farnun sj\u00e1var hefur \u00e1hrif \u00e1 l\u00edfr\u00edki og vistkerfi. Loftslagsbreytingar valda aukinna t\u00ed\u00f0ni \u00f6fgave\u00f0uratbur\u00f0a \u00e1 bor\u00f0 vi\u00f0 storma og st\u00f3ra fellibylji. Loftslagsbreytingar valda einnig hl\u00fdnun, sem annars vegar veldur \u00fev\u00ed a\u00f0 \u00eds br\u00e1\u00f0nar og hins vegar \u00fev\u00ed a\u00f0 sj\u00f3rinn hl\u00fdnar. Hvort tveggja hefur \u00e1hrif \u00e1 l\u00edfr\u00edki, en einnig \u00e1 seltu, strauma og lagskiptingu sj\u00e1var.<\/p>\n Me\u00f0als\u00fdrustig sj\u00e1var s\u00ed\u00f0ustu 20 millj\u00f3n \u00e1r hefur veri\u00f0 nokku\u00f0 st\u00f6\u00f0ugt \u00ed kringum 8,2. S\u00fdrustig sj\u00e1var er \u00fe\u00f3 ekki \u00fea\u00f0 sama alls sta\u00f0ar, heldur er \u00fea\u00f0 breytilegt eftir sta\u00f0setningu enda undir \u00e1hrifum af l\u00edfr\u00edki og \u00fdmsum umhverfis\u00fe\u00e1ttum s.s. hitastigi, seltu og d\u00fdpi. \u00c1hrif l\u00edfr\u00edkis eru nokkur yfir styttri t\u00edma og koma vel fram \u00fear sem \u00e1rst\u00ed\u00f0a g\u00e6tir \u00e1 j\u00f6r\u00f0inni. \u00de\u00e1 h\u00e6kkar pH sj\u00e1var yfir sumarm\u00e1nu\u00f0ina \u00feegar \u00fe\u00f6rungar lj\u00f3still\u00edfa og taka upp kold\u00edox\u00ed\u00f0 \u00far umhverfinu. \u00c1 haustin og yfir vetrarm\u00e1nu\u00f0ina rotnar l\u00edfr\u00e6nt efni og kold\u00edox\u00ed\u00f0 losnar \u00fat \u00ed umhverfi\u00f0 sem lei\u00f0ir aftur til l\u00e6kkunar \u00e1 pH sj\u00e1var. Hitastig sj\u00e1var hefur l\u00edka \u00e1hrif \u00e1 \u00feessa \u00e1rst\u00ed\u00f0asveiflu \u00fear sem leysni kold\u00edox\u00ed\u00f0s er meiri \u00ed k\u00f6ldum sj\u00f3 en hl\u00fdjum. Umhverfism\u00e6lingar vi\u00f0 \u00cdsland s\u00fdna vel \u00feessi \u00e1rst\u00ed\u00f0abundnu \u00e1hrif \u00e1 pH sj\u00e1var en m\u00e6lingarnar s\u00fdna l\u00edka a\u00f0 s\u00ed\u00f0ustu \u00e1ratugi hefur sj\u00f3rinn vi\u00f0 \u00cdsland s\u00farna\u00f0 hratt mi\u00f0a\u00f0 vi\u00f0 \u00fea\u00f0 sem m\u00e6list sunnar \u00ed Atlantshafinu.<\/p>\n Mynd 3.18. N\u00e1tt\u00farlegur breytileiki s\u00fdrustigs hafsins um vetur (vinstra megin) og um sumar (h\u00e6gra megin).<\/p><\/div>\n Losun kold\u00edox\u00ed\u00f0s af mannav\u00f6ldum er farin a\u00f0 breyta \u00fev\u00ed jafnv\u00e6gi sem r\u00edkt hefur \u00ed langan t\u00edma. Fyrir i\u00f0nbyltingu var styrkur kold\u00edox\u00ed\u00f0s (CO2<\/sub>) \u00ed andr\u00famsloftinu 280 ppm og er n\u00fa kominn upp \u00ed r\u00famlega 400 ppm vegna aukinnar losunar gr\u00f3\u00f0urh\u00fasalofttegunda. H\u00f6fin hafa teki\u00f0 upp 25-30% af \u00f6llu \u00fev\u00ed kold\u00edox\u00ed\u00f0i sem vi\u00f0 h\u00f6fum losa\u00f0 \u00ed andr\u00famslofti\u00f0 fr\u00e1 i\u00f0nbyltingu. \u00deegar kold\u00edox\u00ed\u00f0 leysist upp \u00ed sj\u00f3num hli\u00f0rast efnajafnv\u00e6gi \u00ed kolefniskerfi sj\u00e1var \u00e1 tvo vegu:<\/p>\n Mynd 3.19. Vinstra megin: Aukinn styrkur kold\u00edox\u00ed\u00f0s \u00ed lofthj\u00fapnum fr\u00e1 1958 til 2012. H\u00e6gra megin: Aukinn styrkur kold\u00edox\u00ed\u00f0s \u00ed sj\u00f3num og samsvarandi l\u00e6kkun pH-gildisins fr\u00e1 1990 til 2012.<\/p><\/div>\n Vi\u00f0 skulum n\u00fa rifja upp kolefniskerfi sj\u00e1var og sko\u00f0a \u00e1hrif aukinnar uppt\u00f6ku \u00e1 kold\u00edox\u00ed\u00f0i. Eins og fram hefur komi\u00f0 gerir kolefniskerfi\u00f0 \u00fea\u00f0 a\u00f0 verkum a\u00f0 sj\u00f3rinn hefur \u201ebuffer-eiginleika\u201c, sem \u00fe\u00fd\u00f0ir a\u00f0 meiri breytingar \u00fearf en ella til a\u00f0 eiginleikar sj\u00e1varins breytist. \u00deessi buffereiginleiki sj\u00e1var er mj\u00f6g mikilv\u00e6gur fyrir \u00fdmsar l\u00edfverur sem eru n\u00e6mar fyrir jafnvel sm\u00e1v\u00e6gilegum breytingum \u00e1 s\u00fdrustigi. Aukinn styrkur kold\u00edox\u00ed\u00f0s af mannav\u00f6ldum er \u00fer\u00e1tt fyrir buffer-eiginleikana farinn a\u00f0 hafa \u00e1hrif \u00e1 \u00fea\u00f0 jafnv\u00e6gi sem veri\u00f0 hefur til sta\u00f0ar \u00ed kolefniskerfinu \u00ed mj\u00f6g langan t\u00edma. Allar lofttegundir andr\u00famsloftsins leysast upp \u00ed sj\u00f3. Uppleysanleikinn er h\u00e1\u00f0ur hitastigi og seltu. Lofttegundir leysast best upp \u00ed k\u00f6ldum og l\u00edti\u00f0 s\u00f6ltum sj\u00f3. \u00deegar kold\u00edox\u00ed\u00f0 (CO2<\/sub>) leysist upp \u00ed sj\u00f3num hvarfast \u00fea\u00f0 vi\u00f0 vatn og myndar kols\u00fdru (H2<\/sub>CO3<\/sub>):<\/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 (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 (CO3<\/sub>2-<\/sup>) og vetnisj\u00f3n (H+<\/sup>).<\/p>\n HCO3<\/sub>–<\/sup> \u2194 CO3<\/sub>2-<\/sup> + H+<\/sup><\/p>\n Karb\u00f3nat gengur \u00ed samband vi\u00f0 kals\u00edum (Ca2+<\/sup>) og myndar kalk, kals\u00edumkarb\u00f3nat (CaCO3<\/sub>).<\/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 einnig hafa hitastig og selta \u00e1hrif. H\u00e6gt er a\u00f0 lesa \u00e1 svok\u00f6llu\u00f0u Bjerrum-grafi \u00ed hva\u00f0a \u00e1tt ofangreind efnahv\u00f6rf ganga. Eins og sj\u00e1 m\u00e1 \u00e1 mynd 3.20 eykst styrkur b\u00edkarb\u00f3nats \u00feegar sj\u00f3rinn s\u00farnar (\u00feegar fari\u00f0 er fr\u00e1 brotnu gr\u00e6nu l\u00ednunni \u00fear sem pH er 8,2 a\u00f0 brotnu bleiku l\u00ednunni \u00fear sem pH er 7,8) en styrkur karb\u00f3nats minnkar a\u00f0 sama skapi. \u00deetta \u00fe\u00fd\u00f0ir a\u00f0 \u00feegar sj\u00f3rinn tekur upp auki\u00f0 kold\u00edox\u00ed\u00f0 eykst hlutfallslegur styrkur b\u00edkarb\u00f3nats (HCO3<\/sub>–<\/sup>) og H+<\/sup>-j\u00f3na – og \u00fear me\u00f0 l\u00e6kkar pH – en styrkur karb\u00f3nats (CO3<\/sub>2-<\/sup>) l\u00e6kkar. \u00de\u00e1 ver\u00f0ur minna karb\u00f3nat til sta\u00f0ar en \u00e1\u00f0ur til a\u00f0 mynda kalk (CaCO3<\/sub>).<\/p>\n Mynd 3.20. Bjerrum-graf sem s\u00fdnir hlutfallslega skiptingu \u00e1 milli kold\u00edox\u00ed\u00f0s, b\u00edkarb\u00f3nats og karb\u00f3nats sem fall af s\u00fdrustigi. Brotna gr\u00e6na l\u00ednan s\u00fdnir s\u00fdrustig sj\u00e1var fyrir i\u00f0nbyltingu (8,2), gr\u00e1a l\u00ednan s\u00fdrustig dagsins \u00ed dag (8,1) og bleika l\u00ednan framt\u00ed\u00f0arsp\u00e1 (7,8). \u00deegar fari\u00f0 er fr\u00e1 gr\u00e6nu\/gr\u00e1u l\u00ednunni og a\u00f0 \u00feeirri bleiku (til vinstri \u00e1 x-\u00e1snum, s\u00fdrustigi\u00f0 l\u00e6kkar) eykst hlutfallslegur styrkur b\u00edkarb\u00f3nats l\u00edtillega en styrkur karb\u00f3nats l\u00e6kkar nokku\u00f0 skarpt.<\/p><\/div>\n Mynd 3.21 s\u00fdnir \u00e1 einfalda\u00f0an h\u00e1tt breytingar \u00ed kolefniskerfi sj\u00e1var vi\u00f0 aukna uppt\u00f6ku kold\u00edox\u00ed\u00f0s, \u00fe.e. hvernig styrkur H+<\/sup>\u00a0eykst, styrkur HCO3<\/sub>–<\/sup>\u00a0eykst og styrkur CO3<\/sub>2-<\/sup> minnkar.<\/p>\n Mynd 3.21. Breytingar \u00ed kolefniskerfi sj\u00e1var vi\u00f0 aukna uppt\u00f6ku kold\u00edox\u00ed\u00f0s. Styrkur vetnis- og b\u00edkarb\u00f3natj\u00f3na eykst en styrkur karb\u00f3nats minnkar.<\/p><\/div>\n S\u00fdrustig sj\u00e1var (pH) hefur veri\u00f0 nokku\u00f0 st\u00f6\u00f0ugt \u00ed yfir 20 millj\u00f3n \u00e1r og hafa ber \u00ed huga a\u00f0 n\u00falifandi sj\u00e1varl\u00edfverur \u00fer\u00f3u\u00f0ust \u00e1 \u00feessu t\u00edmabili st\u00f6\u00f0ugleika. Sj\u00f3rinn s\u00farnar n\u00fa hratt mi\u00f0a\u00f0 vi\u00f0 \u00fea\u00f0 sem \u00e1\u00f0ur hefur \u00feekkst og \u00fev\u00ed gefst l\u00edtill t\u00edmi til a\u00f0l\u00f6gunar fyrir l\u00edfr\u00edki\u00f0. \u00d3v\u00edst er hvort n\u00e6gur breytileiki e\u00f0a sveigjanleiki s\u00e9 \u00ed erf\u00f0amengi l\u00edfveranna til \u00feess a\u00f0 a\u00f0lagast \u00feeim breytingum sem b\u00faast m\u00e1 vi\u00f0 \u00e1 n\u00e6stu \u00e1rum og \u00e1ratugum vegna s\u00farnunar og annarra umhverfisbreytinga. Tali\u00f0 er a\u00f0 \u00fe\u00e6r l\u00edfverur sem hafa stuttan l\u00edft\u00edma, \u00fe.e. kynsl\u00f3\u00f0ir endurn\u00fdjast hratt, s\u00e9u l\u00edklegri til a\u00f0 geta a\u00f0lagast en l\u00edfverur sem lifa lengi.<\/p>\n Ef ekkert ver\u00f0ur gert til a\u00f0 draga \u00far losun gr\u00f3\u00f0urh\u00fasalofttegunda mun sj\u00f3rinn s\u00farna um 0,4 pH-stig (SSP5-8.5) til vi\u00f0b\u00f3tar fyrir lok \u00feessarar aldar og ver\u00f0a r\u00e9tt undir 7,7. N\u00e1i \u00fej\u00f3\u00f0ir heims a\u00f0 draga verulega \u00far losun mun sj\u00f3rinn a\u00f0 l\u00edkindum s\u00farna um 0,1 pH-stig (SSP1-2.6) til 2100. S\u00fdrustig sj\u00e1var hefur breyst mismiki\u00f0 \u00e1 mismunandi hafssv\u00e6\u00f0um og hefur s\u00farnunin or\u00f0i\u00f0 einna mest \u00e1 hafsv\u00e6\u00f0inu vi\u00f0 \u00cdsland. Eins og sj\u00e1 m\u00e1 \u00e1 mynd 3.22 mun \u00e1framhaldandi s\u00farnun ver\u00f0a mest \u00e1 hafsv\u00e6\u00f0inu fyrir nor\u00f0an \u00cdsland.<\/p>\n Mynd 3.22. Vinstra megin: S\u00fdrustig sj\u00e1var vi\u00f0 yfirbor\u00f0 \u00e1 heimsv\u00edsu fr\u00e1 1950 til 2015 og sp\u00e1 um s\u00fdrustig til 2100 mi\u00f0a\u00f0 vi\u00f0 mismunandi losun gr\u00f3\u00f0urh\u00fasalofttegunda. H\u00e6gra megin: Breyting \u00e1 s\u00fdrustigi sj\u00e1var til 2080-2100 \u00e1 mismunandi hafsv\u00e6\u00f0um mi\u00f0a\u00f0 vi\u00f0 mismunandi \u00fer\u00f3un \u00ed losun gr\u00f3\u00f0urh\u00fasalofttegunda. \u00cd \u00f6llum svi\u00f0smyndum ver\u00f0ur s\u00farnunin einna mest \u00e1 hafsv\u00e6\u00f0inu vi\u00f0 \u00cdsland.<\/p><\/div>\n S\u00farnun sj\u00e1var hefur tvenns konar \u00e1hrif \u00e1 l\u00edfr\u00edki. Annars vegar er um a\u00f0 r\u00e6\u00f0a bein \u00e1hrif af h\u00e6rri styrk H+<\/sup>-j\u00f3na og hins vegar \u00e1hrif \u00e1 kalkmyndandi l\u00edfverur vegna l\u00e6kkandi styrks karb\u00f3natj\u00f3na. Hvort tveggja hefur \u00e1hrif upp f\u00e6\u00f0uke\u00f0juna. S\u00farnun sj\u00e1var getur haft \u00e1hrif \u00e1 \u00fdmis l\u00edfe\u00f0lisfr\u00e6\u00f0ileg ferli \u00ed l\u00edfverum en d\u00fdr og \u00fe\u00f6rungar sem mynda kalk eru \u00ed mestri h\u00e6ttu vegna \u00feess hve kalkmettunarstig sj\u00e1var er n\u00e1tengt s\u00fdrustiginu. Kalkmyndandi pl\u00f6ntur og d\u00fdr eru mikilv\u00e6gur \u00fe\u00e1ttur \u00ed vistkerfum hafsins og skemmdir \u00e1 \u00feeim e\u00f0a ey\u00f0ilegging \u00feeirra mun hafa mikil \u00e1hrif \u00e1 vistkerfi\u00f0 \u00ed heild. Lengi vel voru \u00e1hrif s\u00farnunar l\u00edti\u00f0 ranns\u00f6ku\u00f0, en ranns\u00f3knum hefur fj\u00f6lga\u00f0 miki\u00f0 \u00e1 s\u00ed\u00f0ustu \u00e1rum og v\u00edsbendingar hrannast upp um v\u00ed\u00f0t\u00e6kar og alvarlegar aflei\u00f0ingar ef ekki ver\u00f0ur dregi\u00f0 verulega \u00far losun kold\u00edox\u00ed\u00f0s. D\u00e6mi eru um a\u00f0 \u00f6rstutt t\u00edmabil \u00ed l\u00edfshlaupi l\u00edfveru, \u00fear sem h\u00fan er s\u00e9rstaklega vi\u00f0kv\u00e6m fyrir s\u00farnun, r\u00e1\u00f0i \u00fev\u00ed hvort l\u00edfveran n\u00e6r a\u00f0 dafna e\u00f0a ekki. Enn vita menn \u00fe\u00f3 tilt\u00f6lulega l\u00edti\u00f0 um getu vistkerfisins til a\u00f0 takast \u00e1 vi\u00f0 breytingar og a\u00f0lagast \u00feeim. \u00cd fors\u00f6gunni hafa hlutfallslega fleiri kalkmyndandi l\u00edfverur d\u00e1i\u00f0 \u00fat \u00feegar hafi\u00f0 hefur s\u00farna\u00f0. Minni kalkmettun hefur \u00e1hrif \u00e1 k\u00f3ralrif sem eru uppeldisst\u00f6\u00f0var um fj\u00f3r\u00f0ungs alls sj\u00e1varl\u00edfs.<\/p>\n L\u00e6gra s\u00fdrustig hefur \u00fdmis \u00e1hrif \u00e1 l\u00edfr\u00edki\u00f0 \u00ed sj\u00f3num. Ranns\u00f3knir benda til \u00feess a\u00f0 heilastarfsemi og lyktarskyn fiska geti truflast ef s\u00fdrustig sj\u00e1var er of l\u00e1gt. Langflest sj\u00e1vard\u00fdr eru vi\u00f0kv\u00e6must \u00e1 lirfustigi. N\u00fdlegar ranns\u00f3knir s\u00fdndu fram \u00e1 vefjaskemmdir \u00ed \u00feorsklirfum \u00ed s\u00farari sj\u00f3. Sl\u00edkar vefjaskemmdir myndu lei\u00f0a til \u00feess a\u00f0 aff\u00f6ll \u00feorsklirfa \u00e1 fyrstu d\u00f6gum eftir klak myndu aukast, n\u00fdli\u00f0un minnka og l\u00edkur \u00e1 l\u00e9legum \u00e1rg\u00f6ngum aukast.\u00a0Mikil \u00f3vissa er \u00fe\u00f3 til sta\u00f0ar um a\u00f0l\u00f6gunarh\u00e6fni tegundarinnar.<\/p>\n<\/a>3.6.1\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 S\u00farnun sj\u00e1var<\/h5>\n
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<\/a><\/a><\/a><\/a>3.6.2 \u00c1hrif s\u00farnunar \u00e1 l\u00edfr\u00edki<\/h5>\n
<\/span><\/strong><\/em>Bein \u00e1hrif h\u00e6kkandi styrks vetnisj\u00f3na (l\u00e6gra s\u00fdrustig (pH))<\/strong><\/em><\/h6>\n