An absorbance-based fiber-optic sensor for CO2(aq) measurement in porewaters of sea floor sediments

被引:9
作者
Hales, B [1 ]
Burgess, L
Emerson, S
机构
[1] Columbia Univ, Lamont Doherty Earth Observ, Palisades, NY 10964 USA
[2] Univ Washington, Ctr Proc Analyt Chem, Seattle, WA 98195 USA
[3] Univ Washington, Sch Oceanog, Seattle, WA 98195 USA
基金
美国国家科学基金会;
关键词
D O I
10.1016/S0304-4203(97)00065-0
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
We present results of the construction, testing and calibration of a sensor designed for in situ measurement of CO2(aq) concentrations in porewaters of sea floor sediments. The sensor relies on pH-dependent absorbance changes of a dye-containing solution enclosed within a gas-permeable membrane. It is rugged enough to withstand insertion several centimeters in sediments without damage, and small enough to make measurements separated spatially by less than or equal to 2 mm. Response time at 20 degrees C is a few minutes. Calibration results imply that the sensor is capable of resolving differences in CO2(aq) concentration of +/-8%, or about 2-3 x 10(-6) M, and is stable over time scales of several hours. Preliminary results from two sea floor locations in the equatorial Atlantic of depths 3300 and 4700 m are qualitatively consistent with simultaneous, adjacent pH electrode measurements. Sensor performance could be improved by adding a system for in situ reagent delivery, and by monitoring a non-absorbing wavelength in the dye absorbance spectrum to decrease dependence on the dye concentration of the internal solution. (C) 1997 Elsevier Science B.V.
引用
收藏
页码:51 / 62
页数:12
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