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| Simulation study to determine the influence of polyvinyl chloride microplastics on the soil water characteristic curve |
| Received:September 17, 2021 |
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| KeyWord:polyvinyl chloride;microplastic;soil water characteristic curve;model analysis |
| Author Name | Affiliation | E-mail | | WANG Zhichao | Department of Energy and Environment, Inner Mongolia University of Science and Technology, Baotou 014010, China | | | NI Jiaxuan | Department of Energy and Environment, Inner Mongolia University of Science and Technology, Baotou 014010, China | | | ZHANG Bowen | Department of Energy and Environment, Inner Mongolia University of Science and Technology, Baotou 014010, China | | | YANG Wenhuan | Department of Energy and Environment, Inner Mongolia University of Science and Technology, Baotou 014010, China | | | LI Weiping | Department of Energy and Environment, Inner Mongolia University of Science and Technology, Baotou 014010, China | sjlwp@163.com |
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| Abstract: |
| To explore the effects of microplastics with different abundances（0.5%, 1%, and 2% of soil dry weight）and particle sizes（150, 550 μm, and 950 μm）on the soil water characteristic curve, 10 different treatments（T0 to T9）were applied in this study. Soil moisture characteristic following the different treatments were measured using a pressure film meter, and the applicability of the van Genuchten（VG） model, Brooks–Corey（BC）model, and other common soil moisture characteristic curve models were evaluated by RETC software combined with the simulated values of each curve. The results showed that the soil moisture content decreased more with increasing soil water suction when the microplastic abundance was 1.0% and 2.0% than with treatment with a microplastic abundance of 0.5%. When the microplastic abundance was 2.0%, the soil moisture content of the three groups with increasing grain sizes from 150 μm to 950 μm showed the most obviously decreasing trend. When the soil water suction value reached 1 500 kPa, the soil moisture content of T9 with a grain size of 950 μm showed the greatest decrease at 49.71% that of T0 without microplastics. The increase in microplastic abundance and particle size increased the proportion of soil macropores and decreased the proportion of soil micropores. The soil residual water content（θr）and shape parameter （n）increased with the increasing microplastic abundance, whereas the saturated water content（θs）and inverse of air intake value （ɑ）decreased with the increasing microplastic abundance. With increases in the microplastic abundance and particle size, the water holding capacity of the soil decreased, proportion of large pores increased, and proportion of small pores decreased. The VG model is more suitable than the BC model for simulating the soil moisture characteristic curve of microplastics, and an increased abundance of microplastics with large particle size may easily affect changes in the soil pore structure. |
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