QX/T 591-2020 in English

Technical background and evolution of the standard

This standard inherits the technical framework of QX/T90-2008 and QX/T153-2012, and for the first time systematically regulates the entire process of tree ring density collection. By introducing X-ray film optical projection technology, the traditional width analysis is extended to the density dimension, providing new parameters such as cell wall thickness for climate reconstruction.

Core Terminology Analysis

Key Technical Process

4.1 Sampling quality control

Requires the selection of more than 10 conifers of the same species, and the wood fiber twist angle must be <30°. Compared with QX/T90-2008, a new sample desugaring and degreasing treatment is added: 80℃ water bath for 48h + ethanol extraction to eliminate resin interference.

6.2 Density measurement specifications

The X-ray projection value is measured using an optical density sensor, which must meet the following requirements:

• Constant temperature and humidity environment (23±1℃, 50%RH)
• Sample thickness measurement accuracy 0.001mm
• Platform moving speed ≤2mm/s

Solutions to implementation difficulties

Application value of the standard

By standardizing the trapezoidal sample cutting (1-3cm, 30° knife angle) and the density calibration coefficient input, the comparability of data from different laboratories is increased by 40%. According to the test of the Urumqi Desert Research Institute, this method can make the temporal resolution of tree ring climate reconstruction accurate to the season.