铜、镉复合污染红壤对黑麦草生长和土壤酶活性的影响

Effect of Cu and Cd combined contamination on growth of ryegrass(Lolium perenne L.) and soil enzymes activities

采用石灰石调节红壤酸性后,利用对铜、镉具有一定耐性的高产牧草黑麦草修复铜、镉复合污染土壤。分析黑麦草的生长、生理生化指标以及土壤中酶活性的变化,探索在修复铜、镉复合污染红壤的同时又满足饲料作物安全种植的土地利用方式。结果表明,对于弱酸性红壤(pH 6.0左右),土壤铜全量较低时(<50 mg/kg),黑麦草的生物量、叶绿素含量、抗氧化酶活力、根系活力和丙二醛(MDA)含量与对照相比差异不大,可用于轻重金属污染土壤的修复。当铜含量较高时(200 mg/kg),尽管黑麦草地上部减产不明显,但对黑麦草的生理指标已出现明显抑制作用,对铜镉的吸收系数明显增加。因此,不适宜在重污染土壤上种植黑麦草。土壤脲酶、过氧化物酶和蛋白酶活性能表征黑麦草-红壤体系中重金属的植物可利用性。

After adjusting the acidity of the test soil with limestone,Cu and Cd combined contaminated red soil was remediated by ryegrass（Lolium perenne L.）,because the ryegrass was not only a tolerant species of Cu and Cd,but also a kind of high yield herbage.The growth and physiological index of ryegrass,together with soil enzyme activities,were analyzed to find new mode to remediate contaminated soil and provide safe forage simultaneously.When total Cu content in the soil was less than 50 mg/kg and soil pH was about 6.0,the biomass,chlorophyll content,antioxidant enzymes,root vigor and malondialdehyde（MDA） content of ryegrass had little difference with the control.So,analytical results indicated that ryegrass could remediate the light contaminated soil.When Cu content was more than 200 mg/kg,physiological quality of the plant was stressed significantly,and the biologic absorption coefficient（BAC） of Cu and Cd increased significantly,although the shoot biomass of the ryegrass was not stressed significantly.So,the ryegrass could not remediate heavy contaminated soil.In addition,three soil enzymes（urease,proteinase and peroxidase） activities could express phyto-availability of heavy metal in red soil-ryegrass system.