区域环境与生态
范英宏,林春野,何孟常,杨志峰.大辽河水系表层沉积物中Cd的迁移动力学及生物有效性[J].环境科学学报,2008,28(12):2583-2589
大辽河水系表层沉积物中Cd的迁移动力学及生物有效性
- Kinetics and bioavailability of Cd in the surface sediments of the Daliao River watersystem
- 基金项目：国家重点基础研究发展计划(973)项目(No.2004CB418502);国家自然科学基金项目(No.40671002)
- 作者
- 单位
- 范英宏
- 北京师范大学环境学院水环境模拟国家重点试验室, 水沙科学教育部重点实验室, 北京 100875
- 林春野
- 北京师范大学环境学院水环境模拟国家重点试验室, 水沙科学教育部重点实验室, 北京 100875
- 何孟常
- 北京师范大学环境学院水环境模拟国家重点试验室, 水沙科学教育部重点实验室, 北京 100875
- 杨志峰
- 北京师范大学环境学院水环境模拟国家重点试验室, 水沙科学教育部重点实验室, 北京 100875
- 摘要：为了研究大辽河水系表层沉积物中Cd的迁移特征及生物有效性,在大辽河水系采集了8个表层沉积物样品.测定了沉积物的理化性质、Cd的总含量和可交换态含量,利用DGT方法和离心方法测定了沉积物孔隙水中Cd的浓度.在试验的基础上采用DIFS模型计算了沉积物中Cd从固相到液相释放的动力学参数Tc和解吸速率常数k-1.结果表明,表层沉积物中Cd的总含量为0.16～4.86mg·kg-1,高于中国土壤和辽宁省土壤背景值.离心法测定的孔隙水中Cd的浓度为0.28～3.88ng·mL-1,而DGT测定的浓度为0.08～0.72ng·mL-1.DGT测定的浓度CDGT比离心方法测定的孔隙水浓度低,体现了平衡分配方法和动力学方法在预测生物有效性方面的差异.DIFS模拟结果表明,沉积物中Cd的响应时间Tc和解吸速率常数k-1跨度非常大,分别为10.16～9.999×106s和0.01×10-6～558.16×10-6s-1,体现了沉积物中Cd在固/液相之间反应的动力学差异.此外,吸附态和液相之间的平衡分配系数Kd也是影响沉积物中Cd从固相到液相的再补给能力和生物有效性的重要因素.
- Abstract：To investigate the kinetics and bioavailability of Cd in the surface sediment of the Daliao River watersystem, the physical-chemical characteristics of 8 sediment samples, including organic matter content, clay content and pH, were measured and total and exchangeable contents of Cd in the sediment samples were determined. The concentration of Cd in the pore water was measured by DGT (diffusive gradient in thin film) and centrifugation. Based on the measured data, the DIFS model (DGT induced fluxes in sediment) was used to evaluate the kinetics of sorption/desorption of Cd in the surface sediments. The total content of Cd in the surface sediment was 0.16～4.86 mg·kg-1, higher than the background content of Cd in the soils of China and Liaoning province. The concentrations of Cd in the pore water measured by DGT and centrifugation were 0.08～0.72 ng·mL-1 and 0.28～3.88 ng·mL-1, respectively. The DGT measured concentration, CDGT, was lower than the equilibrium concentration in pore water, showing the difference of the equilibrium and dynamic methods in evaluating bioavailability. The result calculated by the DIFS model showed that the response time (Tc) and the distribution coefficient (Kd) were important factors influencing the resupply of Cd from solid to solution and the bioavailability of Cd. The response time, Tc and desorption rate constants, k-1 were 10.16～9.999×106s and 0.01×10-6～558.16×10-6 s-1, respectively.
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