国五国六柴油车尾气颗粒物对小白菜(Brassica campestris L.)的生态毒性

Ecological toxicity of exhaust particulates from diesel vehicles in China V and China VI to Bok choy(Brassica campestris L.)

为研究柴油车尾气颗粒物对植物的毒性效应,本研究以执行国五、国六两种排放标准的柴油车为研究对象,测定其尾气颗粒物中重金属含量,并以小白菜(Brassica campestris L.)为受试植物,分析了两种颗粒物对小白菜的毒性效应.结果表明:(1)国五、国六柴油车尾气颗粒物中13种重金属总含量分别为1.04 g·kg^(-1)和0.47 g·kg^(-1),国五柴油车尾气颗粒物重金属含量高于国六柴油车;(2)在两种颗粒物的高浓度胁迫下,小白菜体内叶绿素以及蛋白质的含量均出现显著降低趋势;(3)随着两种颗粒物浓度的升高,植物体内部分氧化应激的酶指标超氧化物歧化酶(SOD)、过氧化氢酶(CAT)呈先上升后下降的趋势,而过氧化物酶(POD)以及丙二醛(MDA)、谷胱甘肽(GSH)呈上升趋势,颗粒物的污染能对小白菜产生较为显著的氧化胁迫效应.(4)21 d的毒性实验后,国五、国六柴油车尾气颗粒物对小白菜鲜重的半数有效浓度(EC50)值分别为76.27 mg·L^(-1)和104.48 mg·L^(-1).综合来看,国六标准的实施有效控制了颗粒物中重金属的含量,并一定程度地降低了其对小白菜的毒性.

In order to investigate the toxic effects of diesel exhaust particles on plants,this study focused on diesel vehicles complying with China V and China VI emission standards.The heavy metal content in the exhaust particles was measured,and analyzed the toxic effects of two particulates on Bok choy(Brassica campestris L.)with that as the test plant.The results show that:①The total content of 13 heavy metals in the exhaust particulate matter of China V and China VI diesel vehicles is 1.04 g·kg^(-1)and 0.47 g·kg^(-1),respectively.The heavy metal content of exhaust particulate matter of China V diesel vehicles is higher than that of China VI diesel vehicles;②Under the high concentration stress of two kinds of particles,the contents of chlorophyll and protein in Bok choy significantly decreased;③With the increase of the concentration of the two kinds of particles,the enzyme for partial oxidative stress,superoxide dismutase(SOD)and catalase showed an initial increase followed by a decrease,while peroxidase(POD),malondialdehyde(MDA)and glutathione(GSH)showed an upward trend.The pollution of particles can produce a more significant oxidative stress effect on Bok choy.④After 21 days of toxicity testing,the half-maximal effective concentrations(EC50)were found to be 76.27 mg·L^(-1)and 104.48 mg·L^(-1)of China V and China VI diesel vehicle emissions,respectively.Overall,the implementation of China VI emission standards effectively controlled the heavy metal content in the exhaust particles and to some extent reduced their toxic effects on Bok choy.