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Laboratory study on coprecipitation of phosphate with ikaite in sea ice
Author(s) -
Hu YuBin,
Dieckmann Gerhard S.,
WolfGladrow Dieter A.,
Nehrke Gernot
Publication year - 2014
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2014jc010079
Subject(s) - coprecipitation , geology , precipitation , sea ice , brine , seawater , phosphate , salinity , mineralogy , geochemistry , oceanography , chemistry , meteorology , inorganic chemistry , physics , organic chemistry
Ikaite (CaCO 3 ·6H 2 O) has recently been discovered in sea ice, providing first direct evidence of CaCO 3 precipitation in sea ice. However, the impact of ikaite precipitation on phosphate (PO 4 ) concentration has not been considered so far. Experiments were set up at pH from 8.5 to 10.0, salinities from 0 to 105, temperatures from −4°C to 0°C, and PO 4 concentrations from 5 to 50 µmol kg −1 in artificial sea ice brine so as to understand how ikaite precipitation affects the PO 4 concentration in sea ice under different conditions. Our results show that PO 4 is coprecipitated with ikaite under all experimental conditions. The amount of PO 4 removed by ikaite precipitation increases with increasing pH. Changes in salinity (S ≥ 35) as well as temperature have little impact on PO 4 removal by ikaite precipitation. The initial PO 4 concentration affects the PO 4 coprecipitation. These findings may shed some light on the observed variability of PO 4 concentration in sea ice.