Zhao Meng, Li Congping, Zhang Cheng, Zhao Yujie, Wang Xuexia, Cao Bing, Xu Li, Zhang Jiajia, Wang Jiachen, Zuo Qiang, Chen Yanhua, Zou Guoyuan
Institute of Plant Nutrition, Resources and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China.
Qujing City Agricultural Environmental Protection Monitoring Station, Yunnan 655000, China.
Sci Total Environ. 2023 Nov 25;901:166434. doi: 10.1016/j.scitotenv.2023.166434. Epub 2023 Aug 19.
The combined pollution of microplastics (MPs) and Cd can affect plant growth and development and Cd accumulation, with most studies focusing on dryland soil. However, the effects of polyurethane (PU) controlled-release fertiliser coated MPs (PU MPs), which widely exist in rice systems, coupled with Cd on plant growth and Cd accumulation under flooding conditions are still unknown. Therefore, in the present study, in situ techniques were used to systematically study the effects of PU MPs and Cd coupling on the physiological and biochemical performance, metabolomics characteristics, rhizosphere bacterial community, and Cd bioavailability of rice in different soil types (red soil/cinnamon soil). The results showed that the effects of PU MPs on rice growth and Cd accumulation were concentration-dependent, especially in red soil. High PU concentration (1 %) inhibited rice root growth significantly (44 %). The addition of PU MPs inhibited photosynthetically active radiation, net photosynthesis, and transpiration rate of rice, mainly with low concentration (0.1 %) in red soil and high concentration (1 %) in cinnamon soil. PU MPs can enhance the expression of Cd resistance genes (cadC and copA) in soil, enhance the mobility of Cd, and affect the metabolic pathways of metabolites in the rhizosphere soil (red soil: fatty acid metabolism; cinnamon soil: amino acid degradation, heterobiodegradation, and nucleotide metabolism) to promote Cd absorption in rice. Especially in red soil, Cd accumulation in the root and aboveground parts of rice after the addition of high concentration PU (1 %) was 1.7 times and 1.3 times, respectively, that of the control (p < 0.05). Simultaneously, microorganisms can affect rice growth and Cd bioavailability by affecting functional bacteria related to carbon, iron, sulfur, and manganese. The results of the present study provide novel insights into the potential effects of PU MPs coupled with Cd on plants, rhizosphere bacterial communities, and Cd bioavailability.
微塑料（MPs）与镉的复合污染会影响植物生长发育和镉积累，大多数研究集中在旱地土壤。然而，广泛存在于水稻系统中的聚氨酯（PU）控释肥料包膜微塑料（PU MPs）与镉在淹水条件下对植物生长和镉积累的影响仍不清楚。因此，在本研究中，采用原位技术系统研究了PU MPs与镉耦合对不同土壤类型（红壤/黄棕壤）水稻生理生化性能、代谢组学特征、根际细菌群落和镉生物有效性的影响。结果表明，PU MPs对水稻生长和镉积累的影响具有浓度依赖性，尤其是在红壤中。高PU浓度（1%）显著抑制水稻根系生长（44%）。添加PU MPs抑制了水稻的光合有效辐射、净光合作用和蒸腾速率，主要表现为红壤中低浓度（0.1%）和黄棕壤中高浓度（1%）。PU MPs可以增强土壤中镉抗性基因（cadC和copA）的表达，增强镉的迁移性，并影响根际土壤（红壤：脂肪酸代谢；黄棕壤：氨基酸降解、异生物质降解和核苷酸代谢）中代谢物的代谢途径，从而促进水稻对镉的吸收。特别是在红壤中，添加高浓度PU（1%）后水稻根和地上部分的镉积累分别是对照的1.7倍和1.3倍（p < 0.05）。同时，微生物可以通过影响与碳、铁、硫和锰相关的功能细菌来影响水稻生长和镉生物有效性。本研究结果为PU MPs与镉耦合对植物、根际细菌群落和镉生物有效性的潜在影响提供了新的见解。
