School of Energy and Environmental Engineering, Beijing Key Laboratory of Resource-Oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, Beijing 100083, China; State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; Chengdu Drainage Co., Ltd, Chengdu 610011, China.
Sci Total Environ. 2024 Nov 15;951:175602. doi: 10.1016/j.scitotenv.2024.175602. Epub 2024 Aug 21.
To protect agro-systems and food security, study on the effect of microplastics and heavy metals on edible plants is of great significance. Existing studies mostly used virgin microplastics to evaluate their effects on plants, effects of naturally aged microplastics and their combined effects with heavy metals are rarely explored. In this study, single and combined effect of polyethylene microplastics (PE, both virgin and naturally aged) and cadmium (Cd) on pakchoi under seedling and mature stages were analyzed from perspectives of growth inhibition, oxidative damage, nutrition content and soil enzyme activities. Results showed that inhibiting effects of naturally aged PE (PEa) on the growth of pakchoi were stronger than virgin PE (PEv), whereas co-contamination of PEa and Cd was less toxic than that of PEv and Cd. The co-contamination of PE and Cd could inhibit pakchoi dry biomass by over 85 %. Both single and combined contamination of PE and Cd promoted soil fluorescein diacetate hydrolase (FDA) activities, which were 1.11 to 2.04 times of that in control group. Soluble sugar contents under co-contamination of PEa and Cd were 14 % to 22 % higher than those in control group. PEa and PEv showed different effects on oxidative damage of pakchoi. Compared with PEv, catalase (CAT) activities were more sensitive with PEa, whereas PEa had lower effect on superoxide dismutase (SOD) activities. The response of pakchoi to PE and Cd changed with growth stage. Chlorophyll contents in pakchoi under seedling stage were generally higher than those under mature stage. For Cd contaminated soils, PE benefited pakchoi growth under seedling stage, i.e. antagonistic effect between Cd and PE but hindered their growth under mature stage, i.e. synergistic effect. The results unraveled here emphasized PE, especially PEa, could trigger negative effects on agro-systems, whereas PE could be beneficial for heavy metal contaminated agro-systems under specific situations.
为了保护农业系统和食品安全，研究微塑料和重金属对食用植物的影响具有重要意义。现有研究大多使用原始微塑料来评估其对植物的影响，很少探索自然老化微塑料的影响及其与重金属的联合作用。在这项研究中，从生长抑制、氧化损伤、营养含量和土壤酶活性等方面分析了聚乙烯微塑料（PE，原始和自然老化）和镉（Cd）对小白菜在幼苗期和成熟期的单一和联合作用。结果表明，自然老化 PE（PEa）对小白菜生长的抑制作用强于原始 PE（PEv），而 PEa 和 Cd 的共污染毒性小于 PEv 和 Cd。PE 和 Cd 的共污染可抑制小白菜干生物量超过 85%。PE 和 Cd 的单一和联合污染均促进了土壤荧光素二乙酸酯水解酶（FDA）活性，是对照组的 1.11 至 2.04 倍。PEa 和 Cd 共污染下的可溶性糖含量比对照组高 14%至 22%。PEa 和 PEv 对小白菜氧化损伤的影响不同。与 PEv 相比，过氧化氢酶（CAT）活性对 PEa 更敏感，而 PEa 对超氧化物歧化酶（SOD）活性的影响较低。PE 和 Cd 对小白菜的响应随生长阶段而变化。幼苗期小白菜的叶绿素含量普遍高于成熟期。对于 Cd 污染土壤，PE 在幼苗期有利于小白菜的生长，即 Cd 和 PE 之间存在拮抗作用，但在成熟期阻碍了它们的生长，即存在协同作用。这里揭示的结果强调了 PE，特别是 PEa，可能对农业系统产生负面影响，而在特定情况下，PE 可能有利于重金属污染的农业系统。
