CN-122017144-A - Plant stalk carbon sink in-situ measurement device and method

CN122017144ACN 122017144 ACN122017144 ACN 122017144ACN-122017144-A

Abstract

The application relates to the technical field of plant physiological and ecological monitoring, in particular to a plant stalk carbon sink in-situ measurement device which comprises a split type shell used for being buckled on a plant stalk, wherein a port of the split type shell used for buckling the plant stalk is provided with a self-adaptive dynamic sealing system, the self-adaptive dynamic sealing system comprises an inflatable elastic sealing piece and a pressure regulating unit connected with the inflatable elastic sealing piece in a gas path, and the method for measuring the plant stalk carbon sink comprises the following steps of closing the split type shell on the periphery of the plant stalk to be measured through a two-stage locking mechanism, executing an air tightness self-checking program, entering a dynamic measurement mode, recording gas exchange data and opening the split type shell.

Inventors

QI YAHUI
YAN WEITAO
ZHANG HEBING
WANG SHIDONG
Qiao Xuning
LIU XUAN

Assignees

河南理工大学

Dates

Publication Date: 20260512
Application Date: 20260212

Claims (10)

1. The plant stalk carbon sink in-situ measurement device comprises a split type shell provided with an air inlet interface and an air outlet interface, wherein the split type shell is used for being buckled on plant stalks, and a cavity for measurement is formed between the inner wall of the split type shell and the plant stalks; The self-adaptive dynamic sealing system is characterized in that a port of the split type shell for buckling the plant stalk is provided with the self-adaptive dynamic sealing system, and the self-adaptive dynamic sealing system comprises an inflatable elastic sealing element and a pressure adjusting unit connected with the inflatable elastic sealing element in a gas path, wherein the pressure adjusting unit is used for keeping the internal pressure of the inflatable elastic sealing element to be constant within a set pressure threshold value range.
2. The plant stalk carbon sink in situ measurement device of claim 1, wherein the inflatable elastic seal has a flexible contact layer facing the plant stalk and a rigid contact layer in mechanical sealing connection with the port of the split housing for buckling the plant stalk.
3. The plant stalk carbon sink in-situ measurement device according to claim 1, wherein the pressure regulating unit comprises a miniature air pump, an air pressure sensor arranged in an air guide pipeline, a pressure relief valve and a controller, and the controller is respectively and electrically connected with the miniature air pump, the air pressure sensor and the pressure relief valve.
4. The plant stalk carbon sink in situ measurement device of claim 2, wherein the flexible contact layer is of different wall thickness than the rigid contact layer; The flexible contact layer is a first silica gel layer with the Shore hardness of 10A-20A, and the surface of the first silica gel layer is uniformly distributed with micron-sized hydrophobic convex structures which are used for being attached to irregular textures on the surface of a plant stalk; the rigid contact layer is a second silica gel layer with the Shore hardness of 40A-60A, and an independent gas expansion cavity is formed between the rigid contact layer and the first silica gel layer through a high-frequency hot pressing process; the rigid contact layer and the split type shell are used for buckling the ports of the plant stems and are bonded to form airtight sealing connection.
5. The plant stalk carbon sink in situ measurement apparatus of claim 3, wherein the controller comprises a pressure maintenance module, the maintenance module comprising a hysteresis comparison circuit configured with a first voltage threshold corresponding to the lower pressure threshold and a second voltage threshold corresponding to the upper pressure threshold; The pressure maintaining module is configured to avoid high-frequency oscillation of the pneumatic circuit at a critical pressure point, and only when the voltage signal output by the air pressure sensor jumps out of a hysteresis interval defined by the first voltage threshold value and the second voltage threshold value, a control signal is output to change the switching state of the miniature air pump or the pressure relief valve.
6. The plant stalk carbon sink in-situ measurement device according to claim 1, wherein the junction surface of the split type shell is sealed by a thermal response compensation sealing mechanism, the thermal response compensation sealing mechanism comprises a shape memory alloy material with a two-way memory effect, is embedded in a sealing groove formed in the junction surface of the split type shell, and is used for actively compensating a gap generated by expansion and contraction of the junction surface of the split type shell when the environmental temperature changes.
7. The plant stalk carbon sink in-situ measurement device of claim 6, wherein the thermal response compensation sealing mechanism comprises an elastic rubber matrix and a nickel-titanium shape memory alloy wire array embedded in the matrix, wherein the nickel-titanium shape memory alloy wire array is trained by heat treatment and is configured to generate austenite phase transformation when the ambient temperature rises to a phase transformation point, generate restoring force along axial shrinkage or radial bending, and drive the elastic rubber matrix to deform so as to fill gaps generated by thermal expansion of the split type shell.
8. The plant stalk carbon sink in situ measurement device of claim 1, wherein the split housing is made of a spectrally selective composite material comprising a transparent polymeric substrate and a multilayer dielectric film deposited by magnetron sputtering on an inner surface of the substrate, the multilayer dielectric film being configured to have a transmittance of greater than 90% for visible light having a wavelength of 400nm-700nm and a reflectance of greater than 85% for infrared light having a wavelength of 700nm-2500 nm.
9. The plant stalk carbon sink in-situ measurement device according to claim 1, wherein a brushless vortex fan for generating spiral descending uniform airflow is arranged in the cavity for measurement, and the brushless vortex fan is fixedly connected with the inner wall of one of the split shells.
10. A method for measuring carbon sink of a plant stalk, comprising the steps of: s1, closing a split type shell on the periphery of a plant stalk to be detected through a two-stage locking mechanism; S2, executing an air tightness self-checking program, wherein the controller controls the micro air pump to inflate the inflatable elastic sealing element to the upper limit of the damage threshold, then the air pump is closed, the pressure drop in 30 seconds is monitored, and if the pressure drop is smaller than a preset value, the sealing is judged to be qualified; s3, entering a dynamic measurement mode, wherein the controller dynamically maintains the pressure in the inflatable elastic sealing element body between 1.0 kPa and 2.0 kPa according to the logic of the hysteresis comparison circuit, and at the moment, starting the rotational flow field generating assembly and switching on an external gas analyzer; And S4, recording gas exchange data, and opening a pressure release valve to enable the inflatable elastic sealing element to completely shrink after the measurement is finished, and then opening the split type shell.

Description

Plant stalk carbon sink in-situ measurement device and method Technical Field The application relates to the technical field of plant physiological and ecological monitoring, and relates to a plant stalk carbon sink in-situ measurement device and a plant stalk carbon sink measurement method. Background In global carbon circulation research and "carbon peak, carbon neutralization" strategic background, it is important to precisely quantify the carbon sink capacity of forest ecosystems. Plants act as the main body of carbon fixation of the ecosystem, and the carbon balance contributions of different organs are the core of the study. Traditional photosynthesis and respiration measurements are mainly focused on leaves, which are the main sites of photosynthesis. However, the stems of plants (including the branches of trees and the stems of herbaceous crops) also breathe, and even under certain conditions there is cortical photosynthesis, a non-negligible loop in the overall carbon balance of the plant. Neglecting the carbon flux of the stalks will lead to systematic deviations in the assessment of the carbon sink capacity of the whole ecosystem. In order to achieve in situ measurement of plant stalk carbon flux, a "stalk chamber" (or "assimilation chamber") device is commonly used in the art. The basic principle is that a transparent or opaque cavity is buckled on a plant stalk to be detected to form a closed space isolated from the external environment. The space is connected with an external gas analyzer (such as a portable photosynthesis measurement system) through a gas path pipe to form a closed circuit or open circuit measurement system, and the respiration or photosynthesis rate of the stalk is calculated by monitoring the change rate of the concentration of gases such as CO 2 in the cavity. However, the existing plant stalk carbon sink in-situ measurement device has the common problems of poor sealing adaptability, easy damage to plants, easy air leakage caused by the influence of environmental temperature, uneven internal flow field, non-ideal optical environment and the like, so that the measurement precision is low, the data repeatability is poor, and the application range is narrow. The concrete steps are as follows: First, there are inherent drawbacks in seal reliability and plant suitability. The traditional stem chamber is usually sealed by a rubber or silica gel gasket with fixed size. The disadvantage of this "hard seal" approach is evident 1) poor suitability, the washer of one size is difficult to be used commonly for plant stalks of different diameters or with irregular surface textures (e.g. rough, knotted), frequent replacement of components is required, and the applicability of the device is limited. 2) The pressure is uncontrollable, the locking force applied during installation is completely dependent on the experience of an operator, the epidermis and phloem tissues of the stalks are easily damaged due to excessive pressure, normal physiological activities of plants are affected, and effective sealing cannot be realized due to the fact that the pressure is too small, so that air leakage is caused. To solve this problem, an inflatable air bag type sealing ring is proposed (for example, chinese patent No. CN 206523490U), but it is usually only inflated once, and there is no real-time monitoring and dynamic closed-loop regulation mechanism for sealing pressure. In long-term in-situ monitoring, the initial seal pressure may change due to weak growth of the plant, environmental temperature and humidity changes, or external disturbances, possibly leading to seal failure or sustained stress to the plant. Second, challenges exist in maintaining the hermeticity of the measurement cavity itself. For ease of installation, the cavity housing of the measuring device is typically formed by two or more parts spliced together. In long-term observation in the field, day-night changes or seasonal fluctuations in ambient temperature can cause significant expansion and contraction of the shell material. The deformation can generate tiny and dynamic change gaps at the splicing joint surfaces of the shells, damage the tightness of the whole measuring gas path, lead to the penetration of external gas and cause difficult quantitative interference to the measuring result. The prior art generally lacks effective countermeasures against this problem. Third, there are deficiencies in the accuracy of the environmental simulation within the measurement cavity. On the one hand, the existing device has simpler air flow organization design in the cavity, and a simple air inlet and air outlet are usually arranged on the cavity only. This makes it difficult to form a uniformly mixed flow field within the cavity, which is prone to create gas concentration gradients or flow "dead corners" in localized areas, resulting in non-representative samples collected by the gas analyzer, and thus introducing measurement errors. On