Potential linkage between sedimentary oxygen consumption and benthic flux of biogenic elements in a coastal scallop farming area, North Yellow Sea

Abstract

Surface sediments were collected from a mariculture area adjacent to the Yangma Island suffering from hypoxia in summer, and a laboratory static incubation was conducted to study the sedimentary oxygen consumption (SOC) and the benthic fluxes of nutrients and fluorescent dissolved organic matter (FDOM). Compared with some coastal areas, the SOC of the studied area was relatively low in summer with the value of 2.34-6.03 mmol m^-2 d^-1. Sediment acted as an important source of nutrients (except for nitrate) and FDOM for the overlying water. Dissolved oxygen (DO) in the overlying water could affect the decomposition mode of sedimentary organic matter (SOM), i.e. aerobic and anaerobic decomposition and subsequently dominated the release of nutrients and FDOM. When DO > 50 μmol l^-1, it was beneficial to the release of ammonium, silicate and FDOM. In contrast, low oxygen conditions, i.e. DO < 100 μmol l^-1, stimulated sediment phosphate efflux. In addition, scallop farming activities also affected the SOC and benthic flux of nutrients and FDOM mainly through biological deposition.

Keywords: Coastal biogeochemistry; Laboratory incubation; Mariculture area; Surface sediment; Water-sediment interface.