Sampling device applied to ammonium nitrogen isotope determination and sampling method thereof

Abstract

The invention discloses a sampling device applied to ammonium nitrogen isotope determination. The device comprises an insulating cover. An air inlet hole and an air outlet hole are formed in the isolation cover. An air inlet pipe is mounted on the air inlet hole. The air outlet hole is connected with an exhaust pipe. The exhaust pipe is connected with the gas sampling device. The air inlet pipe isconnected with the air filtering device. The air filtering device comprises a first vacuum pump, a first gas washing bottle and a drying bottle which are connected in series. The air filtering deviceis arranged in the cooling device. A first temperature and humidity sensor facing the ground is installed in the isolation cover. A second temperature and humidity sensor facing the ground is arranged outside the isolation cover. By arranging the air filtering device and the cooling device at the air inlet hole, ammonia gas in air can be removed and extracted, dry and cold air is provided for theinterior of the isolation cover, and the problem that the measured ammonia gas content is inaccurate due to the fact that ammonia gas is blended into water due to condensation of water drops in the cover is solved.

Description

technical field [0001] The invention relates to the field of detection instruments, in particular to a sampling device and a sampling method for ammonium nitrogen isotope determination. Background technique [0002] Ammonia (NH 3 ) as the most important alkaline gas in the atmosphere has an important impact on the environment. NH 3 and acid gases in the air (SO 2 , NO x ) reacts to generate ammonium salt, which is PM 2，5 important constituents. At the same time, NH 3 and NH 4 + It enters the surface ecosystem through dry and wet deposition, which is an important form of nitrogen deposition. Atmospheric NH 3 There are many contributing sources, the main one being the agricultural one. Past studies have shown that atmospheric NH 3 More than half of it comes from agricultural production and life, and nearly 23% of it is contributed by volatilization after fertilization on farmland. [0003] Determine NH 3 The source contribution, corresponding control, can effecti...

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Problems solved by technology

However, this is not applicable to the determination of ammonium nitrogen isotope, which is not a simple subtraction process, so independent sampling of NH3 volatilized from the soil is required

Replacing the long pipe with a gas scrubber is an effective way to remove background NH3, but in the actual test process, it was found that because the volatilization of soil NH3 is strongly affected by light, it must Use a transparent cover, which is similar to a greenhouse. Especially at noon when the light is strong, the temperature inside the cover can rise by more than 10°C in a few minutes. The water vapor in the soil quickly evaporates and condenses into water droplets on the inner wall of the cover, while NH 3 is easily soluble in water, and a large amount of NH3 volatilized by the soil will be adsorbed in the water droplets, which will affect the absorption efficiency of the scrubber and cause the fractionation of ammonium nitrogen isotopes Affect the results; at the same time, too high temperature will affect the volatilization of NH3 [4], resulting in a deviation between the measured NH3 concentration and the actual

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