Ecological significance of biogenic silica in the East China Sea

et al. 2020

JGR Oceans

The concentration of dissolved silicic acid (DSi) and its isotopic composition (δ30Si(OH)4) were determined for the East China Sea (ECS) shelf in the spring season with high spatial resolution. DSi concentrations and δ30Si(OH)4 values ranged from 1.3 to 116.5 μM and +0.85‰ to +2.53‰, respectively. An enrichment of 30Si was observed in most surface‐water samples compared with bottom waters. Several shallow‐water stations at water depths of <20 m reflected the overall control of biological utilization of DSi and regeneration of DSi from biogenic silica (BSi) on the distribution of δ30Si(OH)4 values. A seasonal difference in δ30Si(OH)4 values was observed in the euphotic zone of shelf waters, which is attributed mainly to continuous consumption of DSi in enhanced diatom blooms. The major water masses influencing the ECS shelf were characterized with distinct DSi concentrations and isotopic compositions. Using Si isotopic constraints, modeling of δ30Si(OH)4 values implied that utilization of DSi in the ECS occurred as if in a steady‐state mode. Riverine input was the major DSi source for the surface waters of inner‐shelf areas, as well as part of the middle‐ and outer‐shelf surface waters near the Changjiang River estuary. Upwelled Kuroshio Subsurface Water from the shelf break supported diatom growth in middle‐shelf surface waters. Taiwan Strait Warm Water and Kuroshio Surface Water were relatively oligotrophic, and their influence was confined to waters near the Taiwan Strait and the outer shelf and slope areas.

Section: Discussionmentioning

confidence: 92%

Evaluation of Silicic Acid Sources for Spring Diatom Blooms on the Continental Shelf: Insights FromStable Silicon Isotopes in the East China Sea

Zhang

et al. 2020

JGR Oceans

“…Silicic acid in the leaching solution was analyzed by molybdate-blue spectrophotometry (Mortlock and Froelich 1989), and dissolved aluminum was measured by fluorometry (Ren et al 2001) for mineral correction (Kamatani and Takano 1984). The coefficient of variability (CV) for BSi measurement in the SPM was better than 10% (Liu et al 2005b).…”

Section: Methodsmentioning

confidence: 99%

Nutrient Dynamics in Jiaozhou Bay

Water Air Soil Pollut: Focus

Zhang

et al. 2007

Three cruises were carried out in Jiaozhou Bay (JZB) in the neap tide in October 2002 (fall) and in both neap and spring tides in May 2003 (spring) to understand the relative importance of external nutrient inputs versus physical transport and internal biogeochemical processes. Nutrients (NO À 3 , NO À 2 , NH þ 4 , PO 3À 4 , silicic acid, total dissolved nitrogen (TDN) and phosphorus (TDP), dissolved organic nitrogen (DON) and phosphorus (DOP)) were measured. The concentrations of nutrients were higher in the northern part than in the southern part. High concentrations of NH þ 4 and DON in JZB demonstrated the anthropogenic input. Ambient nutrient ratios indicated that the potential limiting nutrients for phytoplankton growth were silicon, and then phosphorus. Nutrients showed an obvious tidal effect with low values at flood tide and high values at ebb tide. Nutrient elements were transported into JZB in the north and output in the south (i.e., into the Yellow Sea), which varied with season, tidal cycle and investigation sites. Water exchange between JZB and the Yellow Sea exports NO À 3 , NH þ 4 and DON out of JZB, while it inputs PO 3À 4 , silicic acid and DOP into JZB. Nutrient budgets demonstrate that riverine input and wastewater discharge are major sources of nutrients, while residual flow is of minor importance in JZB ecosystem. JZB is a sink for the nutrient elements we studied except for DON. Stoichiometric calculations demonstrate that JZB is a net autotrophic system.

“…There are no historical data for the production rate of bSiO 2 in the YS. However, the production of bSiO 2 can be indirectly estimated via 14 C primary production, the percentage of diatom contribution to primary production and the bSiO 2 /POC ratios of diatom cells (Nelson et al ; Liu et al ; Tréguer and De La Rocha ). It is difficult to obtain the bSiO 2 /POC ratios for typical diatoms under natural conditions (Tréguer et al ).…”

Section: Discussionmentioning

confidence: 99%

“…Diatoms living in nutrient‐replete situations have a constant bSiO 2 /POC atomic ratio (of 0.13 ± 0.05). However, under nutrient‐poor conditions, they can experience great variations in their bSiO 2 /POC ratios in both oceanic and coastal areas (Liu et al ). The concentrations of bSiO 2 and POC in suspended particulate matter of the YS surface water on autumn 2012 were 2.01 ± 2.35 μ mol L −1 (Liu et al ) and 196 μ g L −1 (Sun 2012), respectively.…”

Section: Discussionmentioning

confidence: 99%

“…The global average burial efficiency of bSiO 2 is estimated at 3% (Tréguer et al ; Tréguer and De La Rocha ). The dissolution and preservation of bSiO 2 in the oceans play key roles in the biogeochemical silicon cycle, which is connected to the carbon cycle (Ragueneau et al ; Schlüter and Sauter ; DeMaster ; Liu et al ). However, the availability of silicic acid can limit the growth of diatoms.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Dissolution kinetics of biogenic silica and tentative silicon balance in the Yellow Sea

Limnology & Oceanography

Ren

2017

The dissolution of biogenic silica (bSiO2) in coastal environments is important for marine productivity and essential to the global silicon cycle. BSiO2 dissolution experiments were performed using sediments from the Yellow Sea (YS) to explore the factors that influence bSiO2 dissolution and to better understand the silicon cycle in the YS. The results showed that the bSiO2 content in surface sediments varied from 0.40% to 3.7% (average 2.2% ± 0.79%, SiO2%). Additionally, the bSiO2 content was higher in the central areas of the northern and southern YS and lower in the near‐shore area of the northern Changjiang Estuary. The burial flux of bSiO2 in surface sediments ranged from 0.12 mol m−2 yr−1 to 2.3 mol m−2 yr−1 and gradually decreased eastward from near shore to offshore. Continuous flow experiments showed that the solubilities of bSiO2 in the YS sediments varied from 91.0 to 303 μM‐Si. Further, the dissolution rate constant of bSiO2 was 9.3–41 nmol g−1 h−1, which is 2–3 orders of magnitude lower than that of other marginal seas such as the Arabian Sea and Scotia Sea. The structural incorporation of aluminum in bSiO2 and the content of lithogenic minerals in sediments hindered bSiO2 dissolution. The silica budget of the YS was established. The burial efficiency of bSiO2 in the surface sediment was calculated to be 73%, which accounts for 4% of the global balance and is much higher than that of the global ocean average. Because of its high sediment accumulation rate and much lower dissolution rate constant, bSiO2 was well preserved in the YS, highlighting the important role of the YS in the global silicon cycle.