College of Ecology and Environment, Hainan University, Haikou 570228, Hainan Province, PR China; Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Hainan University, Haikou 570228, Hainan Province, PR China.
College of Ecology and Environment, Hainan University, Haikou 570228, Hainan Province, PR China; Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Hainan University, Haikou 570228, Hainan Province, PR China.
Ecotoxicol Environ Saf. 2021 Jul 1;217:112199. doi: 10.1016/j.ecoenv.2021.112199. Epub 2021 Apr 14.
Environmental aging of ubiquitous microplastics (MP) occurs through the action of biotic and abiotic factors, and aged MP exhibit different physicochemical properties and environmental behavior from virgin MP. This study aimed to investigate the aged micro-sized polystyrene (mPS) and polyvinyl chloride (mPVC), and the heavy metals copper (Cu) and cadmium (Cd), and examine the effects of their combined toxicities on microalga Chlorella vulgaris. Results showed that the presence of MP inhibited cell growth as compared with the control, the inhibition rate (I) decreased as concentrations of MP rose and aged MP exhibited stronger inhibition of cells than did virgin MP. The largest I was achieved in each culture with the MP concentration of 0.01 g/L, in which aged mPS with the maximal of 36.84% (I) followed by aged mPVC (I = 30.03%), virgin mPS (I = 29.10%) and virgin mPVC (I = 16.72%). Addition of the heavy metals Cu and Cd significantly inhibited cell growth, and toxicity increased with concentrations in a range of 0.5-2.0 mg/L; the maximum I values were 19.50% (I) and 85.14% (I), respectively. The combined toxicity of aged MP + Cu or aged MP + Cd was less than that of individual heavy metals. In particular, as compared with the maximal I of 85.14% achieved by single Cd, the toxicity of Cd was greatly reduced when combined with aged mPS and mPVC, with the I value decreased to 27.55% (I) and 32.51% (I), respectively. Both single and combined treatments caused cell damage to the microalga, accompanied by increased superoxide dismutase (SOD) and intracellular malonaldehyde (MDA) content.
环境老化的普遍存在的微塑料（MP）通过生物和非生物因素的作用发生，老化的 MP 表现出与原始 MP 不同的物理化学性质和环境行为。本研究旨在调查老化的微尺寸聚苯乙烯（mPS）和聚氯乙烯（mPVC）以及重金属铜（Cu）和镉（Cd），并研究它们的联合毒性对小球藻的影响。结果表明，与对照相比，MP 的存在抑制了细胞生长，随着 MP 浓度的升高，抑制率（I）降低，老化的 MP 对细胞的抑制作用强于原始 MP。在每个培养物中，MP 浓度为 0.01 g/L 时，最大 I 达到最大，其中老化的 mPS 的最大抑制率为 36.84%（I），其次是老化的 mPVC（I = 30.03%），原始 mPS（I = 29.10%）和原始 mPVC（I = 16.72%）。重金属 Cu 和 Cd 的添加显著抑制了细胞生长，毒性随浓度在 0.5-2.0 mg/L 范围内增加；最大 I 值分别为 19.50%（I）和 85.14%（I）。老化的 MP + Cu 或老化的 MP + Cd 的联合毒性小于单个重金属的毒性。特别是与单一 Cd 达到的最大 I 值 85.14%相比，当与老化的 mPS 和 mPVC 结合时，Cd 的毒性大大降低，I 值分别降低到 27.55%（I）和 32.51%（I）。单一和联合处理都导致微藻细胞受损，同时超氧化物歧化酶（SOD）和细胞内丙二醛（MDA）含量增加。
