The soil is continuously cultivated throughout the year, and some of the pesticides applied to the crops are attached to the crops, and some are scattered in the soil, air and water environment, and some of the pesticides remaining in the soil will be absorbed by the plants. Soil remediation refers to the use of physical, chemical and biological methods to transfer, absorb, degrade and transform pollutants in the soil, reducing its concentration to an acceptable level, or converting toxic and harmful pollutants into harmless substances. The premise of restoration is to analyze the composition of the soil and prescribe the right medicine.

　　To analyze the elements and microstructure of pesticide residues in the soil, the soil needs to be dried first. Both air-drying and drying have the defects of shrinking the volume of the soil sample and changing the state of the soil microstructure. With the decrease of the moisture content, the microstructure of the cohesive soil will also change, and the volume will shrink, which cannot meet the test accuracy of the microstructure research. However, soil samples are prepared in a low-temperature vacuum environment. Due to the low freeze-drying temperature, elements are not easy to volatilize, and in a closed environment, secondary pollution is not easy.

　　1. The sample preparation temperature of the freeze-drying method is low, so that the properties of the semi-volatile substances will be relatively stable and not easy to lose;

　　2. Good dehydration effect, loose texture after freeze-drying, easy to grind and sieve, high work efficiency, but quality problems;

　　3. It is widely used, suitable for testing metal elements, and also suitable for testing semi-volatile and difficult volatile organic compounds.

　　4. The microstructure and volume of the sample after freeze-drying do not change, and 95-99% of the water can be removed. The water content of the soil sample after freeze-drying is about 5%.

　　SGS conducts on-site sampling and laboratory testing of soil and sediment according to standard methods to help prevent and control soil pollution and ensure soil environmental quality and human health and safety.