Journal of Marine Sciences ›› 2018, Vol. 36 ›› Issue (3): 67-75.DOI: 10.3969/j.issn.1001-909X.2018.03.007

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Determination of suspended biogenic silica in the Pearl River Estuary and its adjacent coastal waters in summer

YU Xiao-yong1,2, XU Jie1,2, LONG Ai-min1,2, ZHONG Wan-xuan1,2   

  1. 1. State Key laboratory of Tropical Oceanography,South China Sea Institute of Oceanography,Chinese Academy of Sciences,Guangzhou 510301,China;
    2. University of Chinese Academyof Sciences,Beijing 100049,China
  • Received:2018-04-13 Revised:2018-06-09 Online:2018-09-15 Published:2022-11-26

Abstract: Particulate biogenic silica (BSi) and chlorophyll a (Chl a) were determined at 61 stations in the Pearl River Estuary and adjacent coastal waters in summer, in order to evaluate spatial variability in biogenic silica and the interference of lithogenic silica (LSi) in the bulk silica leached from the alkaline solution. Our results showed that Chl a concentrations ranged from 0.06 to 8.64 μg·L-1. Particulate BSi concentrations varied from the detect limit to 14.3 μmol·L-1, LSi concentrations were 0.00-9.56 μmol·L-1 and the average ratio of LSi to LSi+BSi was 0.38 mol·mol-1. The average ratio of Si to Al was 2.42 mol·mol-1, comparable to the value reported by RAGUENEAU et al(2005). A significant correlation was found between particulate biogenic silica and Chl a, which indicated diatom and phytoplankton biomass in the water column. LSi concentrations varied spatially, with high BSi, LSi and low LSi/(LSi+BSi) ratios in the nearshore area, low BSi, LSi and high LSi/(LSi+BSi) ratios in the offshore waters, low BSi, high LSi and high LSi/(LSi+BSi) ratios in the estuary, high BSi, LSi and high LSi/(LSi+BSi) ratios in the upwelling region. LSi and LSi/(LSi+BSi) ratios in the bottom water were higher than those in the surface water. In addition, some limitations caused by other methodologies of BSi measurements had been discussed.

Key words: biogenic silica, lithogenic silica, LSi/(LSi+BSi) ratio, Si/Al ratio, chlorophyll a, clay minerals

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