Biogeochemistry of dissolved inorganic nutrients in an oligotrophic coastal mariculture region of the northern Shandong Peninsula, north Yellow Sea

Abstract

Fourteen field cruises were carried out in a mariculture region of the northern Shandong Peninsula, North Yellow Sea, China from 2016 to 2017 for a better understanding of the biogeochemical behaviors, sources and export of dissolved inorganic nutrients. The spatial variations of nutrients were not obvious due to the influence of complex hydrological and biochemical conditions. Potential nutritional level was characterized in oligotrophy, and trophic status was rated at medium level. A preliminary estimation of nutrient budgets demonstrated that the dissolved inorganic nitrogen (DIN) load was mainly from atmospheric deposition and scallop excretion, accounting for 56.9% and 35.6% of its total influx. Scallop excretion and sediment release were the major source of phosphate (DIP), contributing to 25.2% and 44.3%, while dissolved silicon (DSi) was mainly from sediment release, accounting for 94.2%. In addition, about 136.7 × 10 3 , 7.3 × 10 3 and 485.5 × 10 3 mol km −2 yr −1 of DIN, DIP and DSi could be converted into other forms, e.g. organic and particulate matter and gas species.

Physical Controls of Summer Variations in Bottom Layer Oxygen Concentrations in the Coastal Hypoxic Region off the Northeastern Shandong Peninsula in the Yellow Sea

“…On the other hand, a comparison of the oxygen solubility and observed DO concentrations indicates that significant oxygen depletion occurs in the bottom layer in the northeastern coastal waters of the Shandong Peninsula in summer (Figure 3). Although ocean stratification is the primary factor at work via restriction of the physical oxygen supply of the surface layer, biogeochemical oxygen consumption, such as respiration of microbes and metazoans, and the decomposition of organic matter, which was strongly temperature‐dependent (Brewer & Peltzer, 2017), continue to lower DO concentrations and even result in hypoxia (Yang & Gao, 2019; Yang et al., 2020; Zhang, Gao, et al., 2018).…”

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

“…Bottom water hypoxia in summer was observed in this area; it generally started to develop in July, reached its maximum in August, and gradually disappeared in autumn (Yang and Gao, 2019). The alternating changes of DO concentration in the bottom water could significantly affect SOC and other diagenetic processes (Yang et al, 2018(Yang et al, , 2020a. The trophic level of water in this area was characterized as oligotrophy, and the sediment was one of the important sources of nutrients for the overlying water (Yang et al, 2020a).…”

“…The alternating changes of DO concentration in the bottom water could significantly affect SOC and other diagenetic processes (Yang et al, 2018(Yang et al, , 2020a. The trophic level of water in this area was characterized as oligotrophy, and the sediment was one of the important sources of nutrients for the overlying water (Yang et al, 2020a). In addition, previous results showed that aerobic microbial degradation of sinking biological particles could be an important source of fluorescent dissolved organic matter (FDOM) based on the correlation between apparent oxygen utilization (AOU) and FDOM, especially for humic-like components (Yang and Gao, 2019).…”

Dynamics and Distribution of Marine Synechococcus Abundance and Genotypes during Seasonal Hypoxia in a Coastal Marine Ranch

“…The maximum depth is about 22 m. Freshwater input from seven streams could affect this area, especially in the rainy season (July and August). It was estimated that scallop excretion contributed to 35.6% of dissolved inorganic nitrogen and 25.2% of phosphate influx in this area [23]. The riverine input may contribute to the high dissolved organic carbon (DOC) and nutrients in the study area [20,23].…”

“…It was estimated that scallop excretion contributed to 35.6% of dissolved inorganic nitrogen and 25.2% of phosphate influx in this area [23]. The riverine input may contribute to the high dissolved organic carbon (DOC) and nutrients in the study area [20,23]. The annual thermal stratification occurs from late spring to late summer.…”