Effects of polystyrene nanoplastics on lead toxicity in dandelion seedlings

Minling Gao; Linsen Bai; Xitong Li; Shengli Wang; Zhengguo Song

doi:10.1016/j.envpol.2022.119349

Effects of polystyrene nanoplastics on lead toxicity in dandelion seedlings

Environ Pollut. 2022 Aug 1:306:119349. doi: 10.1016/j.envpol.2022.119349. Epub 2022 Apr 26.

Authors

Minling Gao¹, Linsen Bai¹, Xitong Li¹, Shengli Wang², Zhengguo Song³

Affiliations

¹ Department of Civil and Environmental Engineering, Shantou University, No. 243 Daxue Road, Shantou, Guangdong Province, 515063, China.
² School of Environmental Science and Engineering, Tiangong University, No. 399 Binshui West Road, Xiqing District, Tianjin, 300387, China.
³ Department of Civil and Environmental Engineering, Shantou University, No. 243 Daxue Road, Shantou, Guangdong Province, 515063, China. Electronic address: forestman1218@163.com.

PMID: 35487467
DOI: 10.1016/j.envpol.2022.119349

Abstract

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 Pb²⁺ than polystyrene and amino-modified polystyrene, and their maximum adsorption amounts were 5.328, 0.247, and 0.153 μg g^-1, 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 Pb²⁺ 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 Pb²⁺, 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 Pb²⁺. Similarly, the bioactive compounds, including flavonoids, polyphenols, and polysaccharides in dandelion, showed a scavenging effect on O₂^- and H₂O₂, 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.

Keywords: Combined toxicity; Heavy metals; Medicinal plant; Oxidative damage; Polystyrene nanoplastics.

MeSH terms

Hydrogen Peroxide / pharmacology
Lead / toxicity
Metals, Heavy* / pharmacology
Microplastics
Plastics / pharmacology
Polystyrenes / toxicity
Seedlings
Taraxacum*

Substances

Metals, Heavy
Microplastics
Plastics
Polystyrenes
Lead
Hydrogen Peroxide