Fast Detection of Carbonate and Bicarbonate in Groundwater and Lake Water by Coupled Ion Selective Electrodes
10.11895/j.issn.0253-3820.150866
- VernacularTitle:双电极法现场快速检测地下水和湖水中碳酸氢根和碳酸根
- Author:
Nan ZHAN
;
Yi HUANG
;
Zhu RAO
;
Xueliang ZHAO
- Publication Type:Journal Article
- Keywords:
Carbon dioxide electrode;
pH electrode;
Bicarbonate;
Carbonate;
Groundwater;
Lake water
- From:
Chinese Journal of Analytical Chemistry
2016;(3):355-360
- CountryChina
- Language:Chinese
-
Abstract:
The content of bicarbonate ( HCO-3 ) and carbonate ( CO2-3 ) ions in groundwater and lake water reflects a broad set of carbon cycling reactions associated with decomposition or synthesis of organic compounds with mineral dissolution or precipitation, which indicates the local geochemical environment. However, the content of HCO-3 and CO2-3 changes easily under the influence of pH, temperature, atmosphere pressure in the process of sampling, transportation and storage, so it has been a worldwide problem to determine the real content of HCO-3 and CO2-3 ions in groundwater and lake water. This article proposed a new way to solve the problem by fast field detection of HCO-3 and CO2-3 ions through the use of pH electrode combined with carbon dioxide electrode. Studies showed in the base solution of pH=4. 8 ± 0. 1, the detection range of HCO-3 ion was 0. 027-570 mg/L and that of CO2-3 was 1. 25 ×10-8-39. 7 mg/L. In the most case, the coexisting ions and weak acid ( K+, Na+, Mg2+, Cl-, SO2-4 <100 mg/L;HSO-3 , NO-2 , HOAc<50 mg/L) did not interfere with the analysis. The method was validated for real water samples and the recoveries were in the range of 95. 2%-99. 2% with the relative standard deviations (RSDs) of 2. 6%-3. 7%. Compared with the acid-base titration method, the accuracy of this method had proved to be good. However, the method could be affected by temperature, so the standard solution and samples should be measured at the same temperature. Above all, this method is suitable for fast field analysis for HCO-3 and CO2-3 ions in the nature water as it is sensitive, fast, economical, and the electrodes are easy to carry and operate. It has been successfully applied in the determination of HCO-3 and CO2-3 in groundwater and lake water in Qinghai Province. Experiment showed that the pH of the groundwater samples from Haidong district was 6 . 4-7 . 4 , with 234-4096 mg/L HCO-3 and 0. 16-1. 89 mg/L CO2-3 . The pH of the lake water samples was about 8. 7, with 1. 36-1. 86 g/L HCO-3 and 32. 3-43. 9 mg/L CO2-3 , which was consistent with the previous results.
