Lei Sun,Wei Zhang,Yakun Feng,Zequn Fan,Lei Jiang,Can Lu
Biodegradable microplastics (BMPs) and cadmium (Cd) present substantial risks to agricultural systems, primarily affecting plants. Most current studies have focused on the ecological effects of virgin BMPs. However, the effects of ultraviolet (UV)-aged BMPs and their interactions with cadmium (Cd) on pakchoi remain largely unknown. Therefore, this study addressed this gap by aging polylactic acid (PLA) microplastics (MPs) through UV irradiation and conducting an indoor hydroponic experiment. The research systematically examined the individual and combined impacts of Cd, virgin, and UV-aged BMPs on pakchoi ( Brassica chinensis L. ), focusing on plant growth, photosynthesis, antioxidant systems, and Cd accumulation. The results showed that after 21 days of UV irradiation (UPLA MPs), UPLA MPs with a fractured surface had a more significant impact on pakchoi than untreated PLA MPs. Cd alone inhibited pakchoi growth, development, and photosynthesis, while PLA/UPLA MPs alone promoted these processes. Under the combination of Cd and PLA/UPLA MPs, UPLA MPs could effectively alleviate the toxic effect of Cd on pakchoi. Besides, Cd coexisted with PLA/UPLA MPs, and with the increase of Cd concentration, UPLA MPs(41.22 %, 66.80 %, 45.57 %) decreased the Cd content of pakchoi more significantly than PLA MPs(37.87 %, 55.91 %, 26.35 %). Meanwhile, the results of Partial least squares structural equation models (PLS-SEM) further showed that UPLA MPs could effectively reduce the accumulation of Cd in plants. Therefore, the results of this study can provide a new perspective and reference for the ecological risk evaluation of Cd and BMPs pollution in agricultural soils.
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.
危险品化学品经营许可证（带存储）