黄海硅的分布与收支研究

基于2012年在黄海的综合调查,对黄海水体和沉积物中溶解硅和生物硅的含量和分布及主要影响因素进行了分析,并结合历史数据建立了黄海硅收支与循环的模型.结果表明,黄海水体溶解硅和生物硅在秋季均高于春季,生物硅占活性硅的22%,陆源输入、初级生产和底界面扩散对硅的含量和分布的影响较为突出.收支表明,底界面扩散是黄海水体溶解硅的主要来源,占外部输入的48%,其次是东海的输入,占32%,河流贡献为9%,地下水贡献为6%,地表径流(非河流部分)贡献为3%,渤海贡献为1.5%,大气仅贡献0.5%;黄海水体溶解硅的支出主要是通过生物的吸收与随后的沉积埋藏和向东海的输出,其比例分别为72%和27%,黄海向渤海输出比例仅为1.0%;黄海沉积物是水体溶解硅的源,同时黄海体系还具有潜在汇的特性;黄海硅的净埋藏量约为55×109mol/a,占当年生物硅总量的7.2%,高于全球海洋的平均比值(3%),是外部输入硅总量的47%.本研究量化了黄海硅循环的主要过程,初步揭示了硅的源-汇特征以及陆地输入对近海硅收支与循环的影响.

Distribution,fluxes and budget of silicon in the Yellow Sea

Based on the comprehensive investigation in the Yellow Sea in 2012, Si concentrations and distributions in the water column and sediment were analyzed; and a budget model of Si in the Yellow Sea was established. The results show that both dissolved silica (DSi) and biogenic silica (BSi) in the water column are higher in Fall than in Spring. BSi accounts for 22% of total reactive Si. DSi and BSi in the water column are largely affected by terrestrial inputs, phytoplankton production and diffusion at the water-sediment interface. Si budget indicates that the major process contributed to the primary production in the water column is the benthic flux, accounting for 48% of total input loading, followed by water exchange from the East China Sea, representing for 32%. Riverine input, groundwater discharge, surface runoff (excluding riverine input) and Bohai Sea input contribute 9%, 6%, 3%, and 1.5% of total Si input, respectively, while the atmospheric deposition holds only 0.5%. The dominant removal of DSi from water column in the Yellow Sea is diatom uptake then sedimentation and export to the East China Sea, accounting for 72% and 27%, respectively, while output to Bohai Sea contributes only 1.0%. Net burial of BSi is about 55×109mol/a, representing 7.2% of primary production and accounting for 47% of exogenetic Si inputs into the Yellow Sea. This study quantifies the main processes of Si cycling, and reveals the source-sink characteristics and the influence of terrestrial loadings on the Si budget in the Yellow Sea.