Farmland soil micro-plastic detection method

Abstract

The invention provides a farmland soil micro-plastic detection method. The farmland soil micro-plastic detection method comprises the steps that a soil sample is subjected to primary digestion, primary flotation and fraction filtration, and a Fenton reagent is adopted as a digestion solution in the primary digestion. According to the farmland soil micro-plastic detection method, the flotation effect is remarkably improved, the recovery rate of micro-plastic is high (78.3%-89.4%), meanwhile, after size fraction treatment, ATR-FTIR and 8700 LDIR instruments are adopted for detection, the lower limit of the detected particle size is remarkably reduced, the detection accuracy is improved, and the labor burden is greatly relieved.

Description

technical field [0001] The invention relates to the technical field of soil detection, in particular to a detection method of farmland soil microplastics. Background technique [0002] The abundance of microplastics in farmland soil has been a hot issue in recent years, but the quantitative analysis of microplastics in soil has always been a technical difficulty. The quantification of farmland soil microplastics is mainly divided into three steps: sampling, extraction and detection. Sampling needs to be selected according to the characteristics of microplastics on the basis of conventional soil sampling methods. At present, the most commonly used microplastic separation methods in various media include removal of organic matter and density separation. Compared with samples from rivers, lakes, oceans, sediments or glaciers, soil components are the most complex. Microplastics are related to soil matrix and humus. The adhesion of other organic matter is also tighter. In the s...

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Problems solved by technology

Evenly dividing sampling points and five-point sampling are commonly used soil sampling techniques, but since one of the important sources of soil microplastics is mulch, and the distribution of mulch in farmland is usually closely related to the location of crops, in order to facilitate crop growth, crop roots The nearby mulch is usually removed in advance, so evenly dividing sampling points and sampling by the five-point method are likely to cause large systematic errors; in the soil environment, microplastics are closely bonded to soil particles, making the actual density of microplastics much greater than the theoretical value. Flotation before digestion will greatly reduce the extraction rate of soil microplastics; microscopic infrared spectrometers usually have two modes: point scanning and surface scanning. The application does not clearly indicate which mode is used. Point scanning requires researchers to distinguish Suspected microplastic particles are detected, and further collection of spectra takes a short time, and the amount of data is small, but the false detection rate is high. Surface scanning is an automatic scanning of all areas of the stage by the instrument, and the false detection rate is low, but it takes a long time and (useless) data large

[0004] Publication No. CN112284867A discloses a method for separating and extracting soil residual microplastics. The method first extracts microplastics by using the extract solution, and then uses H 2 o 2 Purification of microplastics with sulfuric acid is similar to the method of Publication No. CN111982852A. First flotation and then digestion will greatly reduce the extraction rate of soil microplastics, and sulfuric acid is corrosive to microplastics, which interferes with subsequent identification.

[0005] Publication number CN110715835A discloses a method for separating microplastics in environmental soil or sediment based on the combination of flotation and centrifugation. The digestion solution used in this method is H 2 o 2 , the digestion reaction is very violent; the supernatant obtained by flotation is further centrifuged, and the supernatant is taken again for subsequent analysis. This has no effect on the standard microplastic particles, but the surface of the microplastics in the actual environmental samples is attached to soil particles. And it cannot be completely removed by digestion, and centrifugation may discard some of the excessively adhered microplastics; the detection method used in this method is visual inspection + infrared identification, and only microplastic particles > 200 μm can be detected. too high

[0006] Publication No. CN112505182A discloses a Py-GC / MS analysis method for microplastics in agricultural soils. The digestion solution used in this method is H 2 o 2 , the digestion reaction is very violent, and using Py-GC / MS to detect microplastics can only obtain the total weight of all microplastics, but cannot obtain multiple information such as the type, particle size, area, and shape of each microplastic particle, and these Information matters in microplastics research

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