中文摘要：

铁异化还原是铁循环的重要过程，微生物可还原铁（Ⅲ）（MR-Fe（Ⅲ））含量是铁异化还原能力及高活性铁含量的重要参数。利用盐酸羟胺提取法定量研究了胶州湾沉积物中MR-Fe（Ⅲ）含量及深度变化。结果表明，胶州湾表层沉积物中MR-Fe（Ⅲ）含量在7．82-27．9／,mol／g之间，为高活性铁氧化物的一部分、总活性铁很小一部分；可能与受污水输入的影响有关，其含量与黏土组分无明显相关性。MR-Fe（Ⅲ）含量在15cm深度范围内的快速减小，化学还原和异化还原可能对其减小都有一定贡献。但在深部并未耗尽，表明无论铁的异化还原还是快速的硫化物缓冲（即快速的化学还原）都不会受高活性铁氧化物含量的制约，有机质活性应是制约这些过程的最终因素。对具有相对较小的生态环境调节能力的半封闭海湾，进一步研究气候及生态环境改变条件下铁异化还原对有机质矿化的相对贡献、对硫和营养盐以及重金属元素成岩循环的影响具有重要意义。

英文摘要：

Dissimilatory Fe（Ⅲ） reduction is an important iron cycling process, and the content of micro-bially reducible Fe（Ⅲ） （MR-Fe（Ⅲ）） is an important parameter to characterize dissimilatory Fe（Ⅲ） re-duction potential and to quantify the highly reactive Fe（Ⅲ）. In this study, hydroxylamine hydrochloride extraction was used to quantify contents and depth profiles of MR-Fe（Ⅲ） in Jiaozhou Bay sediments at se-lected sites. The results show that MR-Fe（Ⅲ） contents in the surface sediments are in the range of 7.82 - 27.9 μmol/g, being a portion of highly reactive Fe and only a small fraction of total Fe. The MR-Fe （Ⅲ） contents have no apparent correlation with the clay fraction due probably to wastewater discharges to the bay. Within the upper 15 cm, the MR-Fe（Ⅲ） contents decrease quickly downcore, and both biotic and abiotic reduction of Fe（Ⅲ） may have contributed to the decrease, but the decrease has not resulted in com-plete depletion of MR-Fe（Ⅲ） in the deep sediments, indicating that the availability of reactive organic matter but not the highly reactive Fe（Ⅲ） contents should be the factor limiting both dissimilatory reduc- tion and rapid sulfide buffering （i. e. , rapid chemical reduction）. For the semi-closed Jiaozhou Bay with limited self-adjusting capacity, a further study on the relative contribution of dissimlatory Fe（Ⅲ） reduc-tion to organic matter oxidation in the sediments, and its effects on cycling of sulfur, nutrients and heavy metals is of particular importance.