大块的塑料通过风化转化为微塑料颗粒,磨损,和紫外线辐射,显著影响土壤生态系统。然而,关于生物可降解微塑料替代传统微塑料作为农业地膜以驱动受温室气体影响的生物地球化学过程的研究仍处于初始阶段,提供有限的相关报告。本研究旨在研究微塑料和秸秆添加对不同土壤中CO2和N2O排放的影响。在这里,利用黄棕壤(S1)和潮土(S2),每种都用三种不同浓度的PLA(聚乳酸)微塑料(0.25%,2%,和7%w/w)在25°C下持续35天,有和没有稻草添加。结果表明,秸秆(1%w/w)显着增加土壤CO2的4.1倍和3.2倍,分别,N2O分别为1.8倍和1.8倍,分别,与对照相比,S1和S2的累积排放量。PLA微塑料在高浓度下显著增加了71.5%和99.0%的CO2排放量,减少了30.1%和24.7%的N2O排放量(7%w/w,PLA3)在S1和S2中与对照相比,分别。在一起添加秸秆和微塑料的情况下观察到相同的趋势。结构方程模型和冗余分析证实了土壤理化参数,酶和微生物活性是调节CO2和N2O排放的关键因素。微塑料的添加相当于碳源的添加,会显著影响DOC,MBC,SOC和碳相关细菌(CbbL)的丰度,从而增加土壤CO2排放。单独添加微塑料抑制了氮循环酶的活性(脲酶活性),增加反硝化微生物的丰度。然而,添加大量的微塑料和秸秆一起释放塑料添加剂,抑制微生物丰度和减少氮循环。这些作用降低了NH4+-N和增加了NO3--N,导致N2O排放量减少。这项研究表明,可生物降解的微塑料可以通过降解来减少土壤塑料残留物的污染。然而,它们的使用还可以增加CO2排放和减少N2O排放。因此,这项研究为进一步研究利用可生物降解的微塑料作为农业覆盖物的影响奠定了基础,特别是关于土壤地球化学和温室气体排放。
Large pieces of plastic are transformed into microplastic particles through weathering, abrasion, and ultraviolet radiation, significantly impacting the soil ecosystem. However, studies on biodegradable microplastics replacing traditional microplastics as agricultural mulching films to drive the biogeochemical processes influenced by GHG are still in their initial stages, with limited relevant reports available. This study sought to investigate the effects of microplastic and straw addition on CO2 and N2O emissions in different soils. Herein, yellow-brown soil (S1) and fluvo-aquic soil (S2) were utilized, each treated with three different concentrations of PLA (polylactic acid) microplastics (0.25%, 2%, and 7% w/w) at 25 °C for 35 days, with and without straw addition. The results showed that straw (1% w/w) significantly increased soil CO2 by 4.1-fold and 3.2-fold, respectively, and N2O by 1.8-fold and 1.8-fold, respectively, in cumulative emissions in S1 and S2 compared with the control. PLA microplastics significantly increased CO2 emissions by 71.5% and 99.0% and decreased N2O emissions by 30.1% and 24.7% at a high concentration (7% w/w, PLA3) in S1 and S2 compared with the control, respectively. The same trend was observed with the addition of straw and microplastics together. Structural equation modeling and redundancy analysis confirmed that soil physiochemical parameters, enzyme and microbial activities are key factors regulating CO2 and N2O emissions. The addition of microplastics is equivalent to the addition of carbon sources, which can significantly affect DOC, MBC, SOC and the abundance of carbon-associated bacteria (CbbL), thereby increasing soil CO2 emissions. The addition of microplastics alone inhibited the activity of nitrogen cycling enzymes (urease activity), increasing the abundance of denitrifying microbes. However, adding a high amount of microplastics and straw together released plastic additives, inhibiting microbial abundance and reducing the nitrogen cycle. These effects decreased NH4+-N and increased NO3--N, resulting in decreased N2O emissions. This study indicates that biodegradable microplastics could reduce soil plastic residue pollution through degradation. However, their use could also increase CO2 emissions and decrease N2O emissions. Consequently, this research lays the groundwork for further investigation into the implications of utilizing biodegradable microplastics as agricultural mulch, particularly concerning soil geochemistry and GHG emissions.