长江口邻近海域沉积物和间隙水中硅的研究

The study of silica in sediment and pore water in the adjacent area of Changjiang Estuary

以2011年6月和8月在长江口邻近海域采集的沉积物和间隙水样品为研究对象,讨论了沉积物中生物硅(BSi)和间隙水中溶解硅(DSi)的分布情况和影响因素,并初步探讨了生物硅的循环和保存。结果表明,表层沉积物中BSi的含量较低,且均小于1%。柱状沉积物中BSi的含量范围为0.34%~0.52%。C3、D1站位柱状沉积物中BSi的记录主要是由早期成岩过程控制,33#站位的分布特征主要是由水动力等变化控制。沉积物间隙水中DSi的浓度范围为101.6~263.9μmol/L,低于纯BSi的溶解度;间隙水的pH值越大,沉积物的含水率越低,还原性越强,间隙水中DSi的含量越高。3站位生物硅的埋藏效率均较高,表明长江口邻近海域是潜在的硅的汇。沉积通量的分布与沉积速率和埋藏效率的分布一致,均有近岸高于远海的趋势。

Sediment samples and pore water were collected in the adjacent area of Changjiang Estuary in June and August of 2011.The study discussed the distribution characteristics and influencing factors of biogenic silica（BSi）in the sediments and the dissolved silicate（DSi）in the pore water,and the cycle and conservation of biological silicon.The results showed that the content of BSi in the surface sediment was less than 1%.The range of concentration of BSi in core sediments was 0.34%-0.52%.The distribution of BSi in C3 and D1core sediments was controlled by early diagenesis.That of 33#core sediment was mainly caused by the changes of hydrodynamic condition.The range of concentration of DSi in pore water was 101.6-263.9μmol/L,which was lower than the solubility of silica.The higher pH in pore water,lower moisture content and higher reduction of sediments lead the higher concentration of DSi in pore water.The higher silica burial efficiency in these stations showed that the adjacent area of Changjiang Estuary was the potential sink of silica.The distribution of silica sedimentation flux was in a decreasing trend from coastal water to the open sea,which was similar to the distribution of silica deposition rate and silica burial efficiency.