【摘要】 为了研究水文条件对湿地沉积物中铁赋存形态分布的影响,采用Tessier五步连续提取法对贵州草海不同水深梯度下沉积物中铁各形态进行研究.结果表明,草海湿地沉积物中总铁含量在22.8—46.2 g·kg^-1之间,平均值为37.06 g·kg^-1,随着水深升高整体呈下降趋势.草海湿地沉积物中,各形态铁含量大小为残渣态(RES-Fe:7.16—41.22 g·kg^-1)>有机结合态(OM-Fe:1.68—13.94 g·kg^-1)>铁锰氧化物结合态(RED-Fe:2.29—6.96 g·kg^-1)>碳酸盐结合态(CARB-Fe:0.004—0.095 g·kg^-1)>可交换态(EXC-Fe:0.002—0.004 g·kg^-1);各形态铁含量对水深变化响应不一致,RES-Fe、EXC-Fe和Tot-Fe含量随水深加深而减少,RED-Fe和OM-Fe含量随水深加深而增高,CARB-Fe含量无明显变化规律;水文条件影响铁形态组成,季节性积水的S1和S2样点铁含量较高,仅以RES-Fe为主,占总量的87%—91%,而积水较深且长期淹水的S3和S4铁含量较低,以OM-Fe和RES-Fe为主,二者之和占总量的81%—85%.湿地沉积物中铁含量及其形态组成分布会因为水深变化而不同,铁的生物有效性也会因此发生改变,抬升水位有利于提高铁的生物有效性.更多还原

【Abstract】 The occurrence and distribution of different forms of iron in sediments with diverse hydrologic condition of Caohai wetland, Guizhou, were studied by Tessier five step continuous extraction method. The results showed that the iron content in sediments of Caohai wetland was in the range of 22.8—46.2 g·kg^-1, and the average content was 37.06 g·kg^-1, the iron content decreasd with the increase of water depth. The iron content of each form in sediments from Caohai were in the order of RES-Fe(7.16—41.22 g·kg^-1)> OM-Fe(1.68—13.94 g·kg^-1) >RED-Fe(2.29—6.96 g·kg^-1) >CARB-Fe(0.004—0.095 g·kg^-1) >EXC-Fe(0.002—0.004 g·kg^-1). The response of each form of iron content to the change of water depths was inconsistent, the content of RES-Fe,EXC-Fe and Tot-Fe decreased as the depth of water deepened, but the content of RED-Fe and OM-Fe increased with the depth of the water, and no obvious change in the content of CARB-Fe were observed. The hydrological conditions affected the iron composition, the samples from S1 and S2 of seasonal ponding water had higher iron content, RES-Fe was the mainly component accounting for 87%—91% of the Tot-Fe. However, the iron content of S3 and S4 of deep and flooded water was low, and OM-Fe and RES-Fe were the mainly component accounting for 87%—91% of the Tot-Fe. It could be seen that the distribution of iron content and its speciation in wetland sediments varied with the water depths and the bioavailability of iron varied accordingly. The results indicated that the raise the of water level may be beneficial to enhancing the bioavailability of iron.更多还原