Peningkatan keasaman air laut

Peningkatan keasaman air laut adalah peristiwa berkurangnya pH lautan yang berada di bumi, yang disebabkan oleh penyerapan karbon dioksida dari atmosfer (pH berkurang = keasaman meningkat). Diperkirakan 30-40% karbon dioksida yang dilepaskan oleh manusia ke atmosfer larut ke perairan. Untuk mempertahankan kesetimbangan kimia, sebagian akan bereaksi dengan air membentuk asam karbonat. Sebagian dari molekul asam karbonat akan beraksi dengan molekul air membentuk ion bikarbonat dan ion hydronium, sehingga meningkatkan keasaman laut. Antara tahun 1751 hingga 1994, pH permukaan laut diperkirakan menurun dari 8.25 menjadi 8.14, yang merupakan peningkatan konsentrasi ion hydronium sebanyak 30% di lautan.

Peningkatan keasaman air aut diperkirakan memiliki beragam konsekuensi, seperti penurunan laju metabolisme cumi-cumi jumbo (Dosidicus gigas), penurunan sistem imunitas kerang biru, dan pemutihan koral.

Reaksi kimia 

  (g) + H2O (l)   (aq) + H2O (l)  H2CO3 (aq)  HCO3− (aq) + H+ (aq)  CO32− (aq) + 2 H+ (aq)

Reaksi kimia lain juga terjadi sehingga kadar ion karbonat di lautan yang tersedia akan berkurang. Hal ini akan menyulitkan bagi hewan laut yang membutuhkan ion karbonat bagi pertumbuhan hidupnya seperti koral untuk proses kalsifikasi tubuhnya, dan beberapa jenis plankton. Struktur yang mengandung ion karbonat pun akan cepat rapuh karena larut oleh asam. Peningkatan keasaman lautan akan memicu gangguan pada rantai makanan yang ada pada dan terhubung dengan lautan. Sebanyak 105 akademi ilmu pengetahuan telah mengeluarkan rekomendasi untuk mengurangi emisi karbon dioksida global sebanyak setidaknya 50% dari tingkat emisi tahun 1990.

Peningkatan keasaman air laut telah terjadi sebelumnya dalam sejarah bumi, seperti peristiwa Paleocene-Eocene Thermal Maximum (PETM), yang terjadi setidaknya 56 juta tahun yang lalu dan menyebabkan pelarutan struktur karbonat hewan laut hingga membentuk sedimen di basin lautan di seluruh dunia.

Lihat pula 

 Pompa biologis
 Gas rumah kaca
 Global Ocean Data Analysis Project
 Paleocene–Eocene Thermal Maximum
 Dampak lingkungan dari industri batu bara

Referensi 

 
 . Report website.
 , RS Policy document 10/09. Report website.
 
 
 .
 Report website.

Bahan bacaan terkait 

 Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC) (2008). Position analysis: CO2 emissions and climate change: Ocean impacts and adaptation issues. ISSN: 1835–7911. Hobart, Tasmania.
 
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 Kleypas, J. A., R. A. Feely, V. J. Fabry, C. Langdon, C. L. Sabine, and L. L. Robbins. (2006). Impacts of Ocean Acidification on Coral Reefs and Other Marine Calcifiers: A Guide for Further Research , report of a workshop held 18–20 April 2005, St. Petersburg, FL, sponsored by National Science Foundation, NOAA and the U.S. Geological Survei, 88pp.
 
 Riebesell, U., V. J. Fabry, L. Hansson and J.-P. Gattuso (Eds.). (2010). Guide to best practices for ocean acidification research and data reporting, 260 p. Luxembourg: Publications Office of the European Union.

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 CO2SYS , a stand-alone executable (also available in a version for Microsoft Excel/VBA)
 seacarb , a R package for Windows, Mac OS X and Linux (also available here)
 CSYS, a Matlab script

Ekologi perairan
Karbon
Oseanografi kimiawi
Perikanan
Geokimia
Efek pemanasan global
Oseanografi biologi