微塑料与镉及其复合对小麦种子发芽的影响

为了解微塑料与镉单一及其复合污染对水培小麦发芽和幼苗生长的影响，选取农业土壤中普遍存在的两种微塑料聚苯乙烯（mPS）和聚氯乙烯（mPVC），0、100、500 mg·L^-1和1 000 mg·L^-1]、重金属镉（Cd，0、2、10 mg·L^-1和50 mg·L^-1）和小麦种子为试验对象进行种子发芽试验。结果表明：单一微塑料污染下，mPS和mPVC对小麦种子发芽率的影响总体表现为低浓度促进、中高浓度抑制，其中mPVC对小麦种子的发芽指数、发芽势、平均发芽速度均有促进作用，mPS对小麦的生物量有促进作用；单一镉胁迫对小麦种子发芽率的影响基本表现为低浓度（2 mg·L^-1）促进发芽，中高浓度（10 mg·L^-1和50 mg·L^-1）抑制发芽，对小麦芽与根的影响基本表现为低促高抑的规律。微塑料和镉复合污染试验中，与对照组相比，低浓度镉（2 mg·L^-1）-微塑料复合污染抑制小麦种子发芽，其余复合污染几乎对小麦种子的发芽无影响；而低浓度的mPVC与镉复合对小麦种子发芽指数、活力指数、平均发芽速度、根芽的生长和含水率等起协同作用。研究表明，与单一污染处理相比，微塑料-镉复合污染对小麦种子发芽势、活力指数、芽长和生物量的影响基本表现为拮抗作用，即两者复合在一定程度上降低了单一污染物的毒性。

Effect of microplastics, cadmium, and their combination on wheat seed germination

To understand the effects of microplastics, cadmium, and their combination on germination and growth of hydroponic wheat, two common microplasticspolystyrene(mPS) and polyvinyl chloride(mPVC) (] 0, 100, 500 mg·L^-1, and 1 000 mg·L^-1), heavy metal cadmium (Cd) (0, 2, 10 mg·L^-1, and 50 mg·L^-1), and wheat seeds in agricultural soil were selected for seed germination testing. The results showed that overall, mPS and mPVC promoted wheat seed germination at low concentrations, but inhibited wheat seed germination at medium and high concentrations. mPVC promoted the germination index, germination potential, and average germination rate of wheat seeds, whereas, mPS promoted wheat biomass. Cd promoted wheat seed germination at a low concentration(2 mg · L^-1), but inhibited wheat seed germination at medium and high concentrations(10 mg·L^-1 and 50 mg·L^-1). The effect on wheat buds and roots followed the rule of low promotion and high inhibition. When the combined effect of microplastics and cadmium was tested, compared with the control group, low concentration of Cd(2 mg·L^-1) -microplastic inhibited wheat seed germination, but had almost no effect on wheat seed germination. Low concentration of mPVC combined with Cd had synergistic effects on wheat seed germination index, vigor index, average germination rate, root bud growth, and water content. In summary, the combined microplastic-cadmium pollution had antagonistic effects on wheat seed germination potential, vigor index, bud length, and biomass, thereby indicating that the combination of the two pollutants had a reduced toxicity compared to that of either pollutant.