Inqubo Yomjikelezo We-Nitrogen: Ukuphila Kwemvelo Ngokuvumelana
Umjikelezo we-nitrogen ungomunye wemijikelezo ebaluleke kakhulu ye-biogeochemical eMhlabeni, ehilela ukuhamba kwe-nitrogen ngezindlela ezahlukene zamakhemikhali phakathi komkhathi, inhlabathi, amanzi, nezinto eziphilayo. I-nitrogen iyinto ebalulekile, yakha cishe u-78% womkhathi woMhlaba ngesimo segesi ye-nitrogen (N2). Nakuba iningi, lolu hlobo lwe-nitrogen alukwazi ukusetshenziswa ngqo yizinto eziphilayo. Ngakho-ke, umjikelezo we-nitrogen udlala indima ebalulekile ekuguquleni i-nitrogen yomkhathi ibe yizinhlobo ezingasetshenziswa yizitshalo nezilwane. Lesi sihloko sizobuyekeza izigaba eziyinhloko emjikelezweni we-nitrogen.
### 1. Ukulungiswa kwe-nitrogen (Ukulungiswa kwe-nitrogen)
Isigaba sokuqala emjikelezweni we-nitrogen ukufakwa kwe-nitrogen, inqubo lapho igesi ye-nitrogen esemoyeni (i-N2) iguqulwa ibe yi-ammonia (i-NH3) ngesenzo sezinto ezincane noma ngezinqubo ze-abiotic njengombani.
Kunezinhlobo ezimbili eziyinhloko zokulungiswa kwe-nitrogen:
– Ukuqina Kwezinto Eziphilayo: Kwenziwa amabhaktheriya athile, okuhlanganisa nalawo ohlobo lwe-Rhizobium, ahlala emaqhubu ezimpande zemifino njengobhontshisi kanye ne-alfalfa. Lawa mabhaktheriya ane-enzyme i-nitrogenase, engaphula izibopho eziqinile phakathi kwama-athomu e-nitrogen ku-N2 futhi ayiguqule ibe yi-ammonia.
– Ukulungiswa Kwezinto Eziphilayo: Le nqubo yenzeka ngokwemvelo ngombani ohlinzeka ngamandla anele okuphula isibopho se-N2 sibe ama-athomu e-nitrogen ngamanye, abese esabela nomoya-mpilo osemkhathini ukuze akhe i-nitrite ne-nitrate ezithwalwa phansi yimvula.
### 2. Ukwenziwa kwe-Ammon (Ukwenziwa kwe-Ammon)
I-Ammonification, eyaziwa nangokuthi ukubola noma ukwenziwa kwamaminerali, inqubo lapho izinto eziphilayo ezifile, kungaba izitshalo noma izilwane, zihlukaniswa khona yizinto ezincane ze-saprophytic, ezikhiqiza i-ammonia (NH3) noma ama-ion e-ammonium (NH4+). Lezi zinto eziphilayo zihlanganisa amaprotheni, i-DNA, kanye nezinye izinto ze-nitrogen ezicutshini eziphilayo. Lapho izinto eziphilayo zifa futhi kwenzeka ukubola, i-nitrogen ezintweni eziphilayo ibuyiselwa enhlabathini njenge-ammonia, engasetshenziswa kabusha yizitshalo.
### 3. Ukunikeza i-nitrification
I-nitrification inqubo enezigaba ezimbili eguqula i-ammonia (NH3) noma ama-ion e-ammonium (NH4+) ibe yi-nitrite (NO2-) bese iba yi-nitrate (NO3-). Le nqubo yenziwa ngamagciwane anika i-nitrite:
– Isigaba sokuqala: Ukushiswa kwe-ammonia ibe yi-nitrite ngamagciwane abizwa ngokuthi ama-Nitrosomonas.
– NH3 + O2 → NO2- + H2O + H+
– Isigaba sesibili: Ukushiswa okwengeziwe kwe-nitrite ibe yi-nitrate ngamagciwane ahlukene, njenge-Nitrobacter.
– CHA2- + 1/2 O2 → CHA3-
I-nitrate ephumayo ingabe isimuncwa yizimpande zezitshalo njengesakhi esibalulekile noma ibuyiselwe emuva kugesi we-nitrogen yamahhala, kuye ngezimo zemvelo.
### 4. Ukuhlanganiswa
Ukuhlanganiswa yinqubo lapho izitshalo zimunca khona i-nitrate (NO3-) noma i-ammonium (NH4+) enhlabathini ngezimpande zazo. I-nitrate emuncwayo iguqulwa ibe yi-ammonia yi-enzyme i-nitrate reductase emaseli ezitshalo. Le ammonia isetshenziswa ukuhlanganisa ama-amino acid, ama-nucleotide, kanye nezinye izinto eziqukethe i-nitrogen ezidingekayo ekukhuleni nasekuthuthukisweni kwezitshalo. Le nqubo iphinde inikeze umthombo we-nitrogen obalulekile ezilwaneni ezidla lezi zitshalo, okwandisa ukugeleza kwe-nitrogen emazingeni e-trophic emvelweni.
### 5. Ukususwa kwe-nitrification
Ukuguqulwa kwe-nitrification inqubo lapho i-nitrate (NO3-) iguqulwa khona ibe yigesi ye-nitrogen (N2) noma igesi ye-nitrous oxide (N2O) ngochungechunge lwezimpendulo ze-anaerobic ezenziwa amabhaktheriya ahlukanisa i-nitrification, njenge-Pseudomonas ne-Clostridium.
– NO3- → NO2- → CHA → N2O → N2 (g)
Ukususwa kwe-nitrification kwenzeka ikakhulukazi ngaphansi kwezimo ze-anaerobic, njengasenhlabathini egcwele amanzi noma ezinqwabeni zemfucuza yezinto eziphilayo. Le nqubo ibalulekile ngoba isiza ekuvimbeleni ukuqongelela ngokweqile kwama-nitrate ezindaweni zemvelo, okungaholela ekukhuleni kwemizimba yamanzi.
### 6. Indima Yabantu Emjikelezweni We-nitrogen
Imisebenzi yabantu inomthelela omkhulu emjikelezweni we-nitrogen wemvelo. Ukusetshenziswa komanyolo we-nitrogen wokwenziwa kwezolimo kusiza ukwandisa ukuqina kwe-nitrogen, kodwa futhi kunegalelo ekungcolisweni kwemvelo ngokusebenzisa amanzi agelezayo angabangela ukuntuleka kwamanzi emzimbeni. Ukushiswa kwamafutha emvelo kanye nemisebenzi yezimboni nakho kukhiqiza ama-nitrogen oxide, anegalelo ekungcolisweni komoya, imvula ene-asidi, kanye nokushintsha kwesimo sezulu.
### Isiphetho
Umjikelezo we-nitrogen uyisibonelo esiphelele sendlela izinto ezibalulekile ezihamba ngayo ezindaweni zemvelo, ziqinisekisa ibhalansi evumela ukuphila ukuba kuchume. Kusukela ekufakweni kwe-nitrogen, i-ammonification, i-nitrification, i-assimilation, kanye ne-denitrification, isigaba ngasinye sidlala indima exhumene futhi ebalulekile. Ukuqonda nokuqonda ubunzima bomjikelezo we-nitrogen akubalulekile nje kuphela kwisayensi yemvelo kodwa futhi nasemizamweni yethu yokuphatha izinsiza zemvelo kanye nemvelo ngendlela eqhubekayo. Ngokuqwashisa okukhulu ngalo mjikelezo, singathatha izinyathelo zokunciphisa imiphumela emibi yemisebenzi yabantu nokugcina ibhalansi yemvelo yezindawo zethu zemvelo.
