毛竹根际与非根际土壤重金属、理化性质及酶活性特征

摘要

The rhizosphere is an important ecological region that is utilized to study the relationships among plant communities,soil,and microbial communities.In the plant rhizosphere area,particularly in the small region near the root of the plant,there are great differences in acid-base properties,redox potential,and microbial populations than in the general soil because of root secretions.Phytoremediation is a new technology that employs hyperaccumulator plants to remove pollutants from the environment or to render them harmless.Therefore,research focusing on the status and function of the rhizospheric environment in relation to soil contamination has become important in recent years.Moso bamboo is an economic bamboo species that occupies the largest area and is the most widespread species in China.Because of its strong environmental suitability,it is believed that Moso bamboo could be utilized to repair future environmental pollution.To establish the time during which the activity of the root system is optimum,the dynamic changes in soil heavy metal concentration,pH,and soil enzymes were analyzed in the present study.Soil samples were collected from the Moso bamboo forestry near a lead/zinc mine in Quzhou,Zhejiang province,from February 2014 to January 2015.We collected one rhizosphere soil sample and one non-rhizosphere sample during each sampling period.All of the soil samples were a mixture from several sites,with 24 samples in total.The results demonstrated that the pH of the rhizosphere and non-rhizosphere soil for Moso bamboo remained constant during the sampling period,with numbers ranging from 4.50 to 4.85.Water content in the rhizosphere soil was greater than that in the non-rhizosphere,and there was great variation between them,with minimum values measured in June and October.The available Cd and Zn contents of rhizosphere soil were significantly higher than those of non-rhizosphere soil,with the converse occurring for available Pb.The activities of catalase,phosphatase,urease,and dehydrogenase in rhizosphere soils were significantly higher than those in non-rhizosphere soils.There was no significant correlation between soil enzyme activities and absorbable heavy metal concentrations.In rhizosphere soil,only available Pb was significantly negatively correlated with catalase.However,there were highly significant correlations between available Cd and catalase,while the correlation between Cd and urease was negatively significant in non-rhizosphere soil.Our results showed synthetically that the quality of rhizosphere soil was better than that of the non-rhizosphere soil,which could provide some foundation for the application of Moso bamboo as a plant material for renovation.%于2014年2月至2015年1月在浙江省衢州市铅锌矿附近毛竹林地采集土样,对土壤重金属含量、pH以及土壤酶活性等的动态变化特征进行了研究.结果表明:根际土与非根际土的pH在1a中变化均不明显,且变化范围都处在4.50-4.85之间;非根际土的土壤含水率大于根际土,两者的变化幅度较大,最低值均出现在6月和10月;根际土中Zn和Cd的有效态含量远高于非根际土,而Pb的有效态含量则表现出非根际土大于根际土的特点;过氧化氢酶、磷酸酶、脲酶和脱氢酶在根际土中的活性明显高于非根际土;从土壤重金属有效态与土壤酶活性相关性来看,根际土中,除有效态Pb与过氧化氢酶呈显著负相关外,其余重金属元素有效态与土壤酶活性相关性均没有显著相关性,而在非根际土壤中,有效态Cd与过氧化氢酶呈极显著负相关,与脲酶呈显著负相关,Zn和Cd则与土壤酶活性之间没有显著相关性.综合研究结果表明,毛竹根际土壤质量总体上明显优于非根际土,这为毛竹今后作为植物修复的材料提供了一定的理论依据.