Department of Civil and Environmental Engineering, Shantou University, No. 243 Daxue Road, Shantou, Guangdong Province, 515063, China.
School of Environmental Science and Engineering, Tiangong University, No. 399 Binshui West Road, Xiqing District, Tianjin, 300387, China.
Environ Pollut. 2022 Aug 1;306:119349. doi: 10.1016/j.envpol.2022.119349. Epub 2022 Apr 26.
Increasing rates of commercialization and industrialization have led to the comprehensive evaluation of toxic effects of microplastics on crop plants. However, research on the impact of functionalized polystyrene nanoplastics on the toxicity of heavy metals remains limited. This study investigated the effects of polystyrene, carboxy-modified polystyrene, and amino-modified polystyrene on lead (Pb) toxicity in dandelion seedlings. The results showed that carboxy -modified polystyrene with a negative charge absorbed more Pb than polystyrene and amino-modified polystyrene, and their maximum adsorption amounts were 5.328, 0.247, and 0.153 μg g, respectively. The hydroponic experiment demonstrated that single amino-modified polystyrene was more toxic to dandelion seedlings than polystyrene and carboxy-modified polystyrene. The presence of Pb was found to increase antioxidant enzymes (superoxide dismutase and catalase) and non-antioxidant enzymes (glutathione and ascorbic acid) activities in response to excessive reactive oxygen species in dandelion leaves and roots treated with polystyrene and carboxy-modified polystyrene, while it did not change much when amino-modified polystyrene was added. Interestingly, compared with single Pb, the addition of amino-modified polystyrene with positive charges induced an obvious decrease in the above parameters; however, they declined slightly in the treatments with polystyrene and carboxy-modified polystyrene despite a stronger adsorption capacity for Pb. Similarly, the bioactive compounds, including flavonoids, polyphenols, and polysaccharides in dandelion, showed a scavenging effect on O and HO, thereby inhibiting the accumulation and reducing medicinal properties. This study found that the effects of microplastics on the uptake, distribution, and toxicity of heavy metals depended on the nanoparticle surface charge.
商业化和工业化的比例不断增加，导致人们全面评估了微塑料对农作物的毒性影响。然而，关于官能化聚苯乙烯纳米塑料对重金属毒性影响的研究仍然有限。本研究探讨了聚苯乙烯、羧基化聚苯乙烯和氨基化聚苯乙烯对蒲公英幼苗铅毒性的影响。结果表明，带负电荷的羧基化聚苯乙烯比聚苯乙烯和氨基化聚苯乙烯吸收更多的铅，其最大吸附量分别为 5.328、0.247 和 0.153μg/g。水培实验表明，单一氨基化聚苯乙烯对蒲公英幼苗的毒性比聚苯乙烯和羧基化聚苯乙烯更强。研究发现，铅的存在会增加蒲公英叶片和根部的抗氧化酶（超氧化物歧化酶和过氧化氢酶）和非抗氧化酶（谷胱甘肽和抗坏血酸）的活性，以应对过量的活性氧，而当添加氨基化聚苯乙烯时，这些酶的活性变化不大。有趣的是，与单一铅相比，添加带正电荷的氨基化聚苯乙烯会明显降低上述参数；然而，尽管聚苯乙烯和羧基化聚苯乙烯对铅的吸附能力更强，但这些参数在这两种处理中的下降幅度较小。同样，蒲公英中的生物活性化合物，包括类黄酮、多酚和多糖，对 O 和 HO 具有清除作用，从而抑制了它们的积累并降低了药用价值。本研究发现，微塑料对重金属的吸收、分布和毒性的影响取决于纳米颗粒的表面电荷。
