Seasonal variations in the abundance and sinking flux of biogenic silica in Daya Bay, northern South China Sea

Coastal seas account for > 50% of the biogenic silica (BSi) production in marine environments. However, BSi sinking is poorly understood. Here, seasonal variations in the abundance and sinking flux of BSi were investigated in Daya Bay, in the northern South China Sea. The highest BSi concentrations occurred in summer, averaging 8.04 ± 5.48 μmol L-1 (±SD), followed by autumn (5.51 ± 3.11 μmol L-1) and spring (3.76 ± 3.06 μmol L-1). The lowest BSi concentration of 2.93 ± 1.34 μmol L-1 was observed in winter. Based on234Th/238U disequilibria, the average BSi sinking fluxes were 7.08 ± 8.62, 10.01 ± 13.95, and 8.30 ± 13.06 mmol Si m-2 d-1 in spring, summer, and autumn, respectively. The lowest flux of 4.19 ± 3.98 mmol Si m-2 d-1was measured in winter. Together with nitrogen fluxes, the Si:N sinking ratios were 0.8:1.0, 1.5:1.0, 1.6:1.0, and 1.4:1.0 in spring, summer, autumn, and winter, respectively, indicating that particle sinking induces the faster removal of Si compared to N in Daya Bay.

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Opracowanie rekordu w ramach umowy 509/P-DUN/2018 ze środków MNiSW przeznaczonych na działalność upowszechniającą naukę (2019).