Kinetic experiments and the reactive continuum model were combined to characterize the reductive reactivity of iron( Ⅲ) oxides in surface and core sediments of the East China Sea. Three kinetic parameters , i. e. , theoretical amounts of total reactive iron( Ⅲ ) oxides (m0 ) , apparent rate constants (k') , and heterogeneity of reactivity (ν) ,were obtained by fitting kinetic data to the reactive continuum model. The results show that m0 values in the surface sediments are within a narrow range (26. 14～ 60. 51 μmol/g). Normalized initial rates (J/mo=k'),which characterize the kinetic behavior of highly reactive iron( Ⅲ ) oxides, are also within a narrow range, with the highest initial rate being only 7. 25 times the lowest. But heterogeneity of reductive reactivity of iron( Ⅲ ) oxides in the surface sediments displays a wide range of varia-tion. rnThe kinetic rates after 90% dissolution of iron(Ⅲ) oxides are 2～4 orders of magnitude lower than the initial rates. The values of m0 ,K',and 7 for core CO7O2 decrease generally with depth,and display good linear relationships between each other,which could be attributed to diagenetic cycling of iron in the sediments. However,no correlations among m0 ,k and 7 were observed in the surface sediments. In comparison with traditional chemical extraction methods,the reactive continuum model allows a more nuanced picture of the reactivity and kinetic manner of iron( Ⅲ ) oxides in reductive dissolution.%运用还原性溶解动力学实验和活性连续体(reactive continuum)模型表征了东海表层和柱状沉积物中铁(Ⅲ)氧化物的还原活性及反应进程中的动力学行为,通过动力学数据拟合得到了活性铁氧化物理论含量m0、表观速率常数k'和活性非均匀度γ.结果表明,表层沉积物中铁氧化物的m0在26.14～60.51μmol/g之间,变化较小；表征高活性铁氧化物还原动力学行为的标准化初始还原速率(J/m0=k')变化也较小,最大相差仅7.25倍；但不同站位沉积物中铁氧化物活性的非均匀度变化较大,当铁氧化物溶解达到90％时,其速率与初始速率相差2～4个数量级.表层沉积物中铁氧化物的m0,k'和γ3个动力学参数之间不存在相关性；柱状沉积物中m0,k'和γ3个动力学参数都随深度的增加呈总体减小的趋势,且三者之间存在良好的线性关系,这是沉积物早期成岩作用中铁成岩循环的结果.与传统的化学提取相比,活性连续体模型得到3个动力学参数(m0,k'和γ)能从多个角度表征铁氧化物还原活性和动力学行为的细微差别.
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