春季长江口及邻近海域悬浮颗粒态硅的研究

Particulate silicon in the Changjiang Estuary and its adjacent sea in spring

对春季长江口及邻近海域悬浮颗粒态生物硅（PBSi）、成岩硅（LSi）进行了大面调查和围隔培养实验研究,讨论了悬浮颗粒物中PBSi的分布情况及其影响因素。分析表明,PBSi与LSi的含量分别为0.22~4.25和1.75~184μmol/dm3,与世界其他海域相比LSi的含量偏高,PBSi含量则处于中等水平。由于陆源输入的影响,两者含量均在近岸较高,最高值出现在长江口门附近,向外海方向含量逐渐降低。在垂直方向上底层水体含有大量的再悬浮颗粒物,使PBSi与LSi含量皆为底层高于表层。PBSi与溶解态硅酸盐和悬浮颗粒物（SPM）含量密切相关。由于调查期间正值甲藻赤潮暴发,硅藻数量不占优势,导致PBSi与叶绿素的分布趋势存在差异。针对调查海域营养盐的结构特征,对加富营养盐进行了围隔试验,硅藻繁殖速度随PO43-的添加而加快,PBSi含量随之增大,而各围隔袋中LSi的含量主要受到SPM的影响,其平均含量无显著变化。

Suspended particulate matter（SPM） was collected to measure the particulate biogenic（PBSi） and lithogenic（LSi） silica content during May 2003 in the Changjiang Estuary and its adjacent sea.Mesocosm experiments were carried out to discuss the distribution and variation of PBSi and relationships between the PBSi content and other environmental factors.Contents of PBSi and LSi vary from 0.22 to 4.25μmol/dm3 and 1.75 to 184 μmol/dm3,respectively.The content of LSi is much higher than that in the other regions of the world,however,the content of PBSi is at in middle level.Both the contents of PBSi and LSi show higher values in the coastal areas than offshore areas,due to terrigenous input from the Changjiang River.In addition,both the values of PBSi and LSi contents in bottom waters are higher than those in surface waters because of the resuspended SPM.PBSi content is closely related to silicate and SPM.Throughout the sampling period,dinoflagellates was bloom and only a small amount of PBSi was bound to identifiable diatom cells,so the distribution of Chl a was different from that of PBSi.During the mesocosm experiments,the different concents of nutrients were added.The biomass of diatom increases with PO3-4 addition,followed by the higher content of PBSi.LSi content in the mesocosm experiments was mainly determined by SPM,while nutrients had no distrinct influence on the LSi content.