镉与聚苯乙烯微塑料复合胁迫对小油菜生长发育、生理特征及冠层温度影响效应研究

Combined Effect of Cadmium and Polystyrene Microplastics(PS-MPs)on the Growth,Physiological Characteristics,and Canopy Temperature of the Chinese Cabbage Pakchoi(Brassica chinensis).

为明晰镉(Cd)与聚苯乙烯微塑料(PS-MPs)复合胁迫对小油菜生长发育、生理特征、冠层温度的影响效应及内在机制,采用室内水培实验,以小油菜(Brassica chinensis)为供试植物,系统研究Cd与2种粒径(100和1000 nm)PS-MPs复合胁迫对小油菜生长发育、光合色素、抗氧化酶活性、营养品质、解剖结构、冠层群体温度以及Cd吸收转运特性的影响。结果表明,单一Cd及PS-MPs胁迫均显著抑制小油菜生长发育和光合生理过程,其表型指标及光合色素等均随Cd与PS-MPs浓度增加而显著降低。Cd与PS-MPs胁迫显著增强了小油菜氧化应激反应能力,降低了小油菜叶片维生素、可溶性糖和可溶性蛋白含量等品质指标,缩小了小油菜叶片厚度、海绵组织厚度和栅栏组织厚度,显著提升了小油菜植株冠层群体温度。Cd与PS-MPs复合胁迫下低浓度PS-MPs(1 mg·L^(-1))可有效缓解其Cd胁迫抑制效应。随PS-MPs浓度升高(20 mg·L^(-1)),其对小油菜植株生理特征的影响则与Cd胁迫呈协同叠加抑制趋势变化。Cd与PS-MPs复合胁迫对小油菜生长发育及生理特征的影响总体上表现为“低促高抑”的变化趋势。研究结果可为农田土壤Cd及PS-MPs污染生态风险评价提供理论支撑与参考。

To better understand the effects and internal mechanism of the combined contamination of cadmium(Cd)and polystyrene microplastics(PS-MPs)on the growth,physiological characteristics,and canopy temperature of the Chinese cabbage pakchoi(Brassica chinensis),hydroponic experiments were conducted with Cd and two particle sizes of PS-MPs(100 and 1000 nm).Changes in the growth,photosynthetic pigments,antioxidant enzyme activities,nutritional quality,anatomical structure,canopy temperature,and Cd absorption and transport characteristics were measured and analyzed.Results show that stress from either Cd or PS-MPs greatly inhibited the cabbage′s growth and development and the process of photosynthetic physiological.This stress greatly reduced phenotypic indicators and photosynthetic pigments.Moreover,Cd and PS-MPs stress enhanced the oxidative stress response and decreased the vitamin,soluble sugar and protein contents in cabbage leaves.These changes also decreased the thickness of leafy,spongy and palisade parenchym tissues and significantly increased the temperature in the plant canopy.A low PS-MPs concentration(1 mg·L^(-1))effectively alleviated the toxicity of Cd to the cabbage caused by combined stress of Cd and PS-MPs.A high PS-MPs concentration(20 mg·L^(-1))combined with Cd resulted in a compound stress effect,which adversely affected the growth and development of the cabbage.These results can provide basis for ecological risk assessment of Cd and microplastics pollution in agricultural soil.