Li Haixiao, Liu Le
School of Environmental Science and Engineering, Hubei Polytechnic University, Hubei, Huangshi, 435003, China.
College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China.
Chemosphere. 2022 Mar;291(Pt 2):132984. doi: 10.1016/j.chemosphere.2021.132984. Epub 2021 Nov 18.
Microplastics are an emerging threat to soils, but little is known about their effects on soil nitrogen (N) and phosphorus (P) cycling. In this study, a three-month soil incubation experiment has been conducted to analyze the effects of polyethene (PE) and polypropylene (PP) microplastics in sizes of 0-1 mm and 1-5 mm on soil available phosphate, nitrate, and ammonium contents under different fertilization regimes. Soil phosphorus and nitrogen availability were continuously determined in-situ by ion-exchange membrane method during the incubation. Microplastic surface chemical composition and the specific surface area were analyzed by FTIR and BET, respectively. The 16s rRNA sequencing of soil bacterial communities as well as soil pH have been determined after the incubation. The results showed that the presence of microplastics could significantly (P < 0.05) decrease soil available phosphate content from 122.61 mg P L to 63.43 mg P L. The addition of PP microplastics could significantly increase soil available ammonium content from 0.94 mg N L to 1.53 mg N L. Since microplastics had undetectable specific surface area and limited effects on soil microorganisms, adsorption and microorganism alteration functions might not be the main drivers of microplastic effects on soil phosphorus and nitrogen.
微塑料是土壤面临的一种新威胁，但人们对其对土壤氮（N）和磷（P）循环的影响知之甚少。在本研究中，进行了为期三个月的土壤培养实验，以分析0-1毫米和1-5毫米尺寸的聚乙烯（PE）和聚丙烯（PP）微塑料在不同施肥制度下对土壤有效磷、硝酸盐和铵含量的影响。在培养过程中，采用离子交换膜法原位连续测定土壤磷和氮的有效性。分别通过傅里叶变换红外光谱（FTIR）和比表面积分析仪（BET）分析微塑料的表面化学成分和比表面积。培养后测定土壤细菌群落的16s rRNA测序以及土壤pH值。结果表明，微塑料的存在可显著（P<0.05）降低土壤有效磷含量，从122.61毫克P/升降至63.43毫克P/升。添加PP微塑料可显著提高土壤有效铵含量，从0.94毫克N/升增至1.53毫克N/升。由于微塑料的比表面积不可检测且对土壤微生物的影响有限，吸附和微生物改变作用可能不是微塑料影响土壤磷和氮的主要驱动因素。
