Dissolution kinetics of biogenic silica and the recalculated silicon balance of the East China Sea

Bin Wu; SuMei Liu

doi:10.1016/j.scitotenv.2020.140552

Dissolution kinetics of biogenic silica and the recalculated silicon balance of the East China Sea

Sci Total Environ. 2020 Nov 15:743:140552. doi: 10.1016/j.scitotenv.2020.140552. Epub 2020 Jun 26.

Authors

Bin Wu¹, SuMei Liu²

Affiliations

¹ Frontiers Science Center for Deep Ocean Multispheres and Earth System, and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China; Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, China.
² Frontiers Science Center for Deep Ocean Multispheres and Earth System, and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China. Electronic address: sumeiliu@ouc.edu.cn.

PMID: 32659551
DOI: 10.1016/j.scitotenv.2020.140552

Abstract

We conducted field observations in the East China Sea (ECS) in 2010 and 2011 to determine the content and dissolution dynamics of bSiO₂ in sediments of the ECS. The influencing factors on bSiO₂ dissolution were investigated, and the regional silicon budget was recalculated. The sediment bSiO₂ content in the ECS varied from 143 to 583 μmol g^-1. The burial flux of bSiO₂ ranged from 0.11 to 19 mol m^-2 yr^-1 and gradually decreased eastward offshore from within and north of the Changjiang River. Continuous flow experiments showed that the solubility of bSiO₂ in surface sediments varied from 213 to 357 μM-Si, and the dissolution rate constant of bSiO₂ was 14.9-56.6 nmol g^-1 h^-1; both ranges are lower than those of other marginal seas, such as the Arabian and Scotia Seas. The release of soluble aluminum from lithogenic minerals was suggested to influence the pore water build-up of dissolved silica in the ECS. The silicon budget of the ECS was recalculated based on up-to-date research. Due to the low dissolution rate constant and high sediment accumulation rate, sediment bSiO₂ in the ECS is well preserved, with a burial efficiency of 81%; this accounts for 9.9% of the global burial rate and is significantly higher than that of the Yellow Sea and the global ocean average.

Keywords: Biogenic silica; Budget; Dissolution; East China Sea; Lithogenic mineral; Sediment.