Sampling method and device for carbon isotopes in water

Abstract

The invention discloses a sampling method and device for carbon isotopes in water. The method includes the steps that firstly, a sampling bottle is filled with underground water to be sampled and sealed with a silica gel diaphragm plug underwater; secondly, an alkaline solution and a solution for carbonate sedimentation are sequentially injected to the bottom of the sampling bottle through the silica gel diaphragm plug, the same volume of underground water is sucked out of the upper portion of the sampling bottle, and liquid in the sampling bottle is sufficiently and evenly mixed and stands, so sediments deposit at the bottom of the sampling bottle; thirdly, supernate in the sampling bottle is sucked out through the silica gel diaphragm plug, the sediments are reserved, and meanwhile nitrogen with the same volume as the sucked-out supernate is injected; fourthly, the sampling bottle is frozen till the sediments are frozen, the silica gel diaphragm plug is opened, and the sampling bottle is put in a freezing drier to be dried till solid powder is formed.

Description

technical field [0001] The invention relates to the field of carbon isotope sampling, in particular to a method and device for sampling carbon isotope in water. Background technique [0002] Inorganic carbon in water as CO 2 、HCO 3 、H 2 CO 3 , CO 3 form exists, 14 C is a radioactive isotope of carbon, measuring its activity in groundwater can determine the age of groundwater. 14 C dating method is an effective method to study the formation history and evolution law of groundwater. This method is more and more widely used in the research of hydrogeology, hydrology and other disciplines, and its sampling technology is the key to the successful application of this method. The current international sampling method is provided by the IAEA (International Atomic Energy Agency). According to the IAEA method, the China Geological Survey mentioned the sampling method of C isotope in the "Environmental Isotope Survey Program Design and Sample Collection Technical Requirements (G...

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Problems solved by technology

However, these techniques are applicable to the traditional radiation test method, which is characterized by a large sampling volume (2.5g of carbon is required), and the sampling process cannot avoid the interaction with CO in the air. 2 exposure to contamination of raw water samples

[0003] In fact, with the development of C isotope measurement technology, the use of accelerator mass spectrometry has also become a feasible method. The mass of C required by this method is only 1-5 mg, which is 1 / 500 or even less than that of the radiation test method. Compared with this requirement, the above-mentioned existing technology not only has the problem of too large sampling volume and too long time, but also has the disadvantage that it cannot avoid contact with air, which will greatly increase the interference and error caused by such a small sample

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