微塑料与Cd交互作用对小麦种子发芽的生态毒性研究

Study on ecological toxicity of microplastics and cadmium interaction on wheat seed germination

为探究微塑料、重金属以及二者的交互作用对农作物种子生长特性的影响,选取小麦(Triticum aestivum L)为实验对象,开展土壤中微塑料聚乙烯(mPE)和聚丙烯(mPP)(0,10,50,100,200,500,1000,5000和10000mg/kg)与重金属镉(Cd)(0,1和5mg/kg)单一及复合污染对种子萌发的影响研究.结果表明,在本实验所设定的条件下,单一Cd污染对小麦种子萌发特性的影响表现为“低促高抑”规律,小麦种子的根长与芽长随着Cd浓度提升均呈抑制趋势.在单一微塑料污染条件下,m PE对小麦种子的发芽率基本表现为“低抑中促高抑”的规律,mPP对小麦种子发芽率的影响为“低促高抑”.微塑料和Cd复合污染的实验结果表明,与单一微塑料污染对照组相比,微塑料和Cd复合污染会促进小麦根与芽的生长,相比于mPE,复合污染下的m PP对于小麦根长与芽长的促进程度更大,且浓度范围较广(0~1000mg/kg).在Cd浓度为1mg/kg(Cd1)时m PE复合污染的小麦根长、芽长大于Cd浓度为5mg/kg(Cd5)情况下m PE复合污染的长度.在Cd1条件下m PP复合污染的小麦根长、芽长小于Cd5情况下m PP复合污染的长度,微塑料与Cd的复合污染对于芽的影响大于对根的影响.微塑料-Cd复合效应对小麦种子发芽、根长和芽长的影响总体上表现为促进作用,在一定程度上缓解了单一污染物的毒害作用.

In order to identify the behaviors of microplastics, heavy metals and their combined action on the growth characteristics of crop seeds, wheat(Triticum aestivum L) was selected as the experimental subject to conduct the research on the soil enriched microplastics polyethylene(mPE), polypropylene(mPP)(0, 10, 50, 100, 200, 500, 1000, 5000 and 10000mg/kg) and heavy metal cadmium(Cd)(0, 1 and 5mg/kg) single pollution toward seed germination respectively following by their combined effect. From the results derived from single pollution condition of Cd, low concentration of Cd exhibit promoted wheat germination accompanied by inhibition effect on high Cd concentration. Furthermore, both root and bud length displayed the inverse correlation with the Cd concentration. Under the single pollution condition of microplastic, the germination rate of mPE to wheat seeds basically showed a valley type that demonstrated two end are inhibited and medium concentration of mPE can promote the germination rate of wheat seeds. And low concentration of mPP exhibit promoted wheat germination accompanied by inhibition effect on high mPP concentration. In the experiment of microplastic and Cd combined pollution, the experiment result showed that microplastic and Cd compound pollution promoted elongation of wheat root and bud when compared to a single microplastic pollution control group.Under combined pollution, mPP promoted wheat root elongation and bud elongation more than mPE, and the concentration range was wider(0~1000mg/kg). The length of root and bud of wheat seeds contaminated pollute under mPE and Cd pollution(1mg/kg)was longer than that under mPE and Cd pollution(5mg/kg), but under the same conditions, the length of root and bud of wheat seeds contaminated with mPP and Cd pollution(1mg/kg) was shorter than that under mPP and Cd pollution(5mg/kg). The combined effect of microplastics and Cd on the germination, root and bud length of wheat seeds is generally shown as an accelerating effect, which relieves the toxic effect of a single pollutant to a certain extent.