Methane clathrate

**[[methane]] clathrate** (CH4.75H2) ko (4), wanda kuma ake kira **methane hydrate**, **hydromethane**, methane ice, wuta ice, natural **gas hydrate**, ko gas hydrate ne mai ƙarfi clathrate fili (musamman, clathrate hydrate) wanda babban adadin methane ya makale a cikin wani crystal tsarin ruwa, samar da wani m kankara kamar.[2] Asalin da ake zaton yana faruwa ne kawai a yankunan waje na Tsarin hasken rana, inda yanayin zafi yake ƙasa kuma ruwan kankara ya zama ruwan dare, an sami manyan ajiyar methane clathrate a ƙarƙashin turɓaya a kan teku na Duniya (kimanin 1100 m a ƙasa da matakin teku).  An kafa hydrate na Methane lokacin da ruwa mai haɗin hydrogen da iskar methane suka shiga hulɗa a matsin lamba mai girma da yanayin zafi a cikin teku.

Methane clathrates sune abubuwan da aka saba da su a cikin zurfin teku kuma suna faruwa a cikin zurfi mai zurfi kuma suna samar da abubuwan da ke cikin teku. Methane hydrates an yi imanin cewa ya samo asali ne ta hanyar hazo ko crystallisation na methane da ke ƙaura daga zurfi tare da kuskuren yanayin ƙasa. Ruwan sama yana faruwa ne lokacin da methane ya haɗu da ruwa a cikin yanayin teku dangane da zafin jiki da matsin lamba. A cikin shekara ta 2008, bincike a kan Tashar Vostok ta Antarctic da EPICA Dome C ice cores sun bayyana cewa methane clathrates suma suna cikin zurfin ƙanƙara na Antarctic kuma suna yin rikodin tarihin tarin methane na yanayi, wanda ya kasance shekaru 800,000 da suka gabata. Rubuce-rubucen methane na kankara shine tushen farko na bayanai don binciken dumama duniya, tare da iskar oxygen da carbon dioxide.

## Tsarin da abun da ke ciki

Abinda ake kira methane clathrate hydrate abun ciki shine (CH4) 4 (H2) 23, ko 1 mole na methane ga kowane 5.75 moles na ruwa, daidai da 13.4% methane da taro, kodayake ainihin abun da ke ciki ya dogara da yawan kwayoyin methane da suka dace a cikin tsarin cage daban-daban na lattice na ruwa. Yawan da aka lura yana kusa da 0.9 g / cm3, wanda ke nufin cewa methane hydrate zai iyo zuwa saman teku ko tafkin sai dai idan an ɗaure shi a wurin ta hanyar kafa shi a cikin ko kuma an ɗaure ya zuwa turɓaya. Ɗaya daga cikin lita na cikakkiyar methane clathrate mai ƙarfi zai ƙunshi kusan gram 120 na methane (ko kusan lita 169 na iskar methane a 0 °C da 1 atm),[nb 1] ko mita ɗaya na methane clachrate ya saki kusan mita 160 na iskar gas.

## Abubuwan da aka adana na halitta

Methane clathrates an ƙuntata su ga ƙananan lithosphere (watau < 2,000 m zurfi). Bugu da ƙari, ana samun yanayin da ya dace ne kawai a cikin duwatsu na nahiyar a yankunan polar inda matsakaicin yanayin zafi ya kasa da 0 ° C; ko kuma a cikin yanayin teku a zurfin ruwa sama da 300 m inda yanayin zafi na ruwa ke kusa da 2 ° C. Bugu da kari, tabkuna masu zurfi na ruwa mai laushi na iya karɓar iskar gas, misali ruwan sha Lake Baikal, Siberia. An sami ajiyar nahiyoyi a Siberia da Alaska a cikin gadajen sandstone da siltstone a ƙasa da zurfin 800 m. Abubuwan ajiyar teku suna da alama sun bazu a cikin shelf na nahiyar (duba Fig.) kuma suna iya faruwa a cikin turɓaya a zurfi ko kusa da ƙirar turɓaya-ruwa. Suna iya rufe ma da mafi girma ajiyar gas methane.

### Ruwa na teku
Ana zaton clathrates a cikin waɗannan ajiya masu zurfi sun samo asali ne daga methane da aka samar ta hanyar microbial tun lokacin da darajar δ13C na clathrate da kewaye da methane da ya narke suna kama da juna. Koyaya, ana kuma tunanin cewa ruwan sha da aka yi amfani da shi a cikin matsin man fetur da maɓuɓɓugar gas a cikin permafrost kuma tare da ɗakunan nahiyar a duk duniya sun haɗu da methane na halitta don samar da clathrate a zurfi da matsin lamba tunda methane hydrates sun fi kwanciyar hankali a cikin ruwa mai laushi fiye da ruwan gishiri. Bambance-bambance na cikin gida na iya zama yaduwa tun lokacin da aikin samar da hydrate, wanda ke cire ruwa mai tsabta daga ruwan gishiri, sau da yawa yana iya haifar da karuwar gida da yiwuwar karuwar ruwan gishiri. Hydrates yawanci suna cire gishiri a cikin ruwa mai zurfi wanda ya samo asali. Don haka, suna nuna babban resistivity na lantarki kamar kankara, kuma sinadarin da ke dauke da hydrates suna da resistivism mafi girma fiye da sinadarin ba tare da gas hydrates ba (Alƙali ). 

Wadannan ajiya suna cikin tsakiyar zurfin yanki a kusa da 300-500 m kauri a cikin turɓaya (yankin gas hydrate, ko GHSZ) inda suke tare da methane da aka narke a cikin sabo, ba gishiri ba, ruwa mai zurfi. Sama da wannan yanki methane yana nan ne kawai a cikin narkewar ta a cikin maida hankali wanda ke raguwa zuwa saman laka. A ƙasa da shi, methane yana da iskar gas. A Blake Ridge a kan tasowa na nahiyar Atlantic, GHSZ ya fara ne a zurfin 190 m kuma ya ci gaba zuwa 450 m, inda ya kai daidaituwa tare da yanayin gas. Matakan sun nuna cewa methane ya mamaye 0-9% ta hanyar girma a cikin GHSZ, da kuma ~12% a cikin yankin gas.

## Manazarta