Kum'mawa kwa Tropical North Pacific (ETNP) ndi dera lalikulu, lolimbikira, komanso lokulitsa mpweya wocheperako (OMZ) womwe umatenga pafupifupi theka la gawo lonse la ma OMZ apadziko lonse lapansi. Mkati mwa OMZ pachimake (~ 350-700 m kuya), mpweya wosungunuka umakhala pafupi kapena pansi pa malire ozindikira a masensa amakono (∼10 nM). Ma gradient otsetsereka a okosijeni pamwamba ndi pansi pa OMZ pachimake amatsogolera pakukhazikika kwamagulu ang'onoang'ono omwe amasiyananso pakati pa magawo a particle-associated (PA) ndi free-living (FL). Apa, timagwiritsa ntchito 16S amplicon sequencing (iTags) kusanthula kusiyanasiyana ndi kugawa kwa anthu a prokaryotic pakati pa magawo a FL ndi PA kukula komanso pakati pamitundu yosiyanasiyana ya redox. Mawonekedwe a hydrographic pa malo athu ophunzirira anali osiyana ndi omwe adanenedwapo kale mu ETNP ndi ma OMZ ena, monga ETSP. Tsatani kuchuluka kwa okosijeni (∼0.35 μM) analipo pachimake cha OMZ pamalo athu ochitira zitsanzo. Chifukwa chake, kuchuluka kwa nitrite komwe kumanenedwa kwa ma cores a OMZ kunalibe monga momwe amatsatirira mabakiteriya a anammox (mtundu wa Brocadiales).CandidatusScalindua), yomwe imapezeka kawirikawiri kudutsa malire a oxic-anoxic mu machitidwe ena. Komabe, mabakiteriya a ammonia-oxidizing (AOB) ndi archaea (AOA) amagawira komanso kuchuluka kwa ma autotrophic carbon assimilation rates (1.4 μM C d).-1) idagwirizana ndi kuchuluka kwa ammonium komwe kumadziwika kuti ndipamwamba kwambiri pafupi ndi pachimake cha OMZ. Kuphatikiza apo, mamembala amtunduNitrospina, mabakiteriya owopsa a nitrite-oxidizing (NOB) analipo omwe akuwonetsa kuti ammonia ndi nitrite oxidation zimachitika pakuwunika kwa okosijeni. Kuwunika kwa kuyesa kufanana (ANOSIM) ndi Non-metric Dimensional Scaling (nMDS) kunawonetsa kuti mabakiteriya ndi ma archaeal phylogenetic oimira anali osiyana kwambiri pakati pa magawo a kukula. Kutengera mbiri ya ANOSIM ndi iTag, mapangidwe amisonkhano ya PA sanakhudzidwe kwambiri ndi ulamuliro womwe udalipo wodalira kwambiri biogeochemical kuposa gawo la FL. Kutengera kukhalapo kwa AOA, NOB ndikufufuza mpweya m'kati mwa OMZ tikuwonetsa kuti nitrification ndi njira yogwira ntchito ya nayitrogeni m'chigawo chino cha ETNP OMZ.
Mawu Oyamba
Poyankha kusintha kwa nyengo komwe kukupitilira komanso zochitika za anthu mdera lanu, kuchuluka kwa okosijeni wosungunuka kwacheperachepera panyanja yotseguka komanso m'mphepete mwa nyanja (Breitburg et al., 2018). Kuyerekeza kutaya kwa okosijeni kuchokera kunyanja yotseguka m'zaka 60 zapitazi kupitilira 2% (Schmidtko et al., 2017), kupanga nkhawa zokhudzana ndi zotsatira za kukula kwa madera omwe akusowa mpweya (Paulmier ndi Ruiz-Pino, 2009). Ma OMZ a m'nyanja otseguka amapangika pamene kupanga kwapamwamba kwambiri kumapangitsa kuti mpweya wabwino ukhale wofunikira m'madzi apansi panthaka omwe amaposa mpweya wabwino kwambiri wakuya. Kuchuluka kwa okosijeni m'mizere yamadzi ya OMZ kumatha kukhala ndi ma gradients otsetsereka (oxycline) pamwamba ndi pansi pakatikati pa oxygen-deplete core kupanga hypoxic (nthawi zambiri pakati pa 2 ndi ~ 90 μM), subboxic (<2 μM) ndi anoxic (pansi pa kuzindikira malire (∼10 nM) zigawo za miyeso yosiyana (Bertagnolli ndi Stewart, 2018). Ma oxygen gradients amatsogolera pakukhazikika kwamagulu a metazoan ndi tizilombo tating'onoting'ono komanso njira za biogeochemical motsatira ma oxyclines ochulukirapo (Belmar et al., 2011).
Zina mwazochepa kwambiri za kutaya kwa nayitrogeni zalembedwa mu OMZs za Eastern Tropical North Pacific (ETNP) ndi South Pacific (ETSP) (Callbeck et al., 2017;Penn et al., 2019), Cariaco Basin yokhazikika (Montes et al., 2013), Nyanja ya Arabia (Ward et al., 2009), ndi OMZ ya Benguela upwelling system (Kuypers et al., 2005). M'machitidwe awa, ma microbial process of canonical denitrification (heterotrophic reduction of nitrate to nitrogen intermediates and often to dinitrogen gas) ndi anammox (anaerobic ammonium oxidation) amatsogolera kutayika kwa nayitrogeni komwe kungathe kuchepetsa kupanga koyambirira.Ward et al., 2007). Komanso, mpweya wa oceanic nitrous oxide (wowonjezera kutentha mpweya) wochokera ku microbial denitrification womwe umapezeka mu OMZs akuti umapangitsa pafupifupi gawo limodzi mwa magawo atatu a mpweya wa nitrous oxide padziko lonse lapansi.Naqvi et al., 2010).
ETNP OMZ ndi gawo lalikulu, lolimbikira, komanso lokulitsa mpweya wocheperako womwe umatenga pafupifupi theka la madera onse a OMZ padziko lonse lapansi, ali pakati pa 0-25 ° N latitude ndi 75 ndi 180 ° W longitude (Paulmier ndi Ruiz-Pino, 2009;Schmidtko et al., 2017). Chifukwa cha kufunikira kwawo kwachilengedwe, mitundu ya biogeochemistry ndi mitundu yosiyana siyana ya ETNP OMZ yawerengedwa mozama (mwachitsanzo,Beman ndi Carolan, 2013;Duret et al., 2015;Ganesh et al., 2015;Chronopoulou et al., 2017;Pack et al., 2015;Peng et al., 2015). Kafukufuku wam'mbuyomu adanenanso kuti okosijeni wosungunuka mkatikati mwa OMZ (~250-750 m kuya) nthawi zambiri amakhala pafupi kapena pansi pa malire ozindikira (∼10 nM) (Tiano et al., 2014;Garcia-Robledo et al., 2017). Komabe, m'mphepete mwa kumpoto kwa ETNP's OMZ (malo ophunzirira malo ~22 ° N) mpweya wa oxygen pa 500 mamita ukhoza kufika pakati pa 10 ndi 20 μM (Paulmier ndi Ruiz-Pino, 2009; Zambiri zochokera ku World Ocean Atlas 2013)1. Pamsonkhano wakumunda womwe wanenedwa pano, tidayeza mpweya mu OMZ pachimake pamlingo wokwanira (0.35 μM) kuti tithandizire njira za aerobic microbial, monga ammonium ndi nitrite oxidation, ndikuletsa pang'ono njira zofunika za anaerobic microbial. Njira za aerobic microbial zadziwika kale m'magawo owoneka ngati a subboxic kapena anoxic a ETNP OMZ (Peng et al., 2015;Garcia-Robledo et al., 2017;Penn et al., 2019). Komabe, zinthu zomwe zimayang'anira kugawa ndi ntchito zamagulu enaake ogwira ntchito a tizilombo tating'onoting'ono mu OMZ sizikudziwika bwino.
Kukhalapo kwa ma nitrifiers omwe mpweya suwoneka mu OMZ ukhoza kufotokozedwa ndi kusintha kwaposachedwa kwa oxycline chifukwa cha mpweya wabwino wa okosijeni wa episodic vertical vertical, womwe ukhoza kuchititsa kuti ephemeral trace oxygen levels mkati mwa OMZ cores.Muller-Karger et al., 2001;Ulloa et al., 2012;Garcia-Robledo et al., 2017). Zinthu zosakhalitsa zotere zitha kugwiritsidwa ntchito ndi anthu a aerobic kapena ma microaerophilic, kuphatikiza ma nitrifiers. Kuphatikiza apo, tinthu tating'onoting'ono ta epipelagic (ma cell ophatikizika, ma pellets a fecal, ndi zinthu zovuta za organic) zimatha kukhala ndi mpweya wokwanira.Ganesh et al., 2014). Chifukwa chake, tinthu tating'onoting'ono ta oxygen ndi aerobic titha kutumizidwa kumadzi ena a anoxic, kulola kwakanthawi kagayidwe ka aerobic kuti kachitike mogwirizana ndi tinthu tating'onoting'ono. Tinthu tating'onoting'ono timadziwika kuti ndi malo ochezera a microbial biogeboctionSimon et al., 2002;Ganesh et al., 2014) ndipo imatha kuthandizira kusiyanitsa kwa anaerobic kapena aerobic tizilombo tating'onoting'ono tating'ono tating'ono tating'ono tating'ono tating'ono tating'onoting'ono (Alldredge ndi Cohen, 1987;Wright et al., 2012;Suter et al., 2018).
Mu kafukufuku wapano, tikufufuza madera a prokaryotic omwe akukhala kumpoto kwa ETNP's OMZ ndi zinthu zachilengedwe zomwe zingakhudze kugawanika kwawo molunjika pogwiritsa ntchito 16S amplicon sequencing (iTags) pamodzi ndi ziwerengero zambiri. Tidasanthula zigawo ziwiri zazikulu; gawo la moyo waufulu (0.2-2.7 μm), ndi gawo logwirizana ndi tinthu (> 2.7 μm, kutenga tinthu tating'onoting'ono komanso ma cell a protistan) pazambiri zakuya pamodzi ndi oxycline zomwe zimagwirizana ndi mikhalidwe yosiyana ya redox.
Titha kupereka masensa osungunuka a okosijeni okhala ndi magawo osiyanasiyana, kuti ma cell azitha kuyang'aniridwa munthawi yeniyeni. Takulandirani kuti mukambirane
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Nthawi yotumiza: Jul-05-2024