河流湿地土壤芘的降解和生物有效性模型与酶活性动态变化

Model of Pyrene Degradation and Bioavailability and Dynamic Changes of Enzymatic Activities in the Riverine Wetland Soil

在淹水和非淹水条件下,在河流湿地土壤中加入高浓度(10mg·kg-1)和极高浓度(200mg·kg-1)芘,研究了芘降解过程、芘生物有效性和土壤酶活性的长期动态变化.结果表明,培养91d后,高浓度芘处理的土壤中芘的残留率在淹水和非淹水条件下分别为79.0%和51.4%,而极高浓度处理的芘残留率在淹水和非淹水条件下分别为61.1%和33.9%.利用Tenax-ta树脂提取快速解吸态生物有效芘,结果发现,有效芘浓度在高浓度芘处理的两种土壤中的值比较接近,分别为1.01mg·kg-1和1.23mg·kg-1;而有效芘浓度在极高浓度处理的两种土壤的相应值差别较大,分别为20.31mg·kg-1和9.44mg·kg-1.采用四参数Logistic模型能够精确地拟合芘降解过程和生物有效性变化过程(p<0.0001).土壤蔗糖酶、脲酶和多酚氧化酶对芘污染敏感,而过氧化氢酶对芘污染不敏感.实验结果揭示了河流湿地土壤芘在淹水条件下降解活跃阶段持续时间短和芘生物有效性高的特征以及土壤蔗糖酶、脲酶和多酚氧化酶活性可以作为评估芘污染影响的候选指标.

The long-term degradation and bioavailability of pyrene as well as soil enzymatic activities were studied.Pyrene with high concentration（10mg·kg-1） and extremely high concentration（200mg·kg-1） were added into the waterlogged and non-waterlogged riverine wetland.After 91 days of incubation in room temperature,the residual of pyrene in waterlogged and non-waterlogged soil at extremely high concentration of pyrene addition were 61.1% and 33.9%,respectively,while those in waterlogged and non-waterlogged soil at high concentration of pyrene addition were 79.0% and 51.4%,respectively.At the extremely high rate of pyrene addition,the bioavailable concentrations of pyrene which was extracted from two types of soil using Tenax-ta were 20.31mg·kg-1 and 9.44mg·kg-1,respectively;at the high rate of pyrene addition,the bioavailable concentrations of pyrene in two types of soil were 1.01mg·kg-1 and 1.23mg·kg-1,respectively.The four parameter logistic model exactly（p0.0001） fitted the data of degradation and bioavailablility of pyrene.Additionally,the soil enzymatic activities of invertase,urease and polyphenoloxidase were sensitive to the concentration of pyrene,whereas the soil catalase was not.In conclusion,pyrene in waterlogged riverine wetland soil has short stage of active degradation and high bioavailability;while invertase,urease and polyphenoloxidase could potentially become the candidates of the biological indicator to evaluate the effection of PAHs pollution on soil.