Numerical investigation of nutrient limitations in the Bohai Sea

Abstract

River discharges are the important freshwater and nutrient sources for Bohai Sea (BS), and have a profound impact on the local marine environment. In this paper, the annual cycles of nutrient and phytoplankton dynamics in 1980s were reproduced using a coupled biogeochemical-physical model. Based on the validated simulations, the nutrient limitation characters were further investigated by running the model with the riverine nutrient altered, first enriching nitrogen and then phosphorus. It was found that although the riveine N:P ratios in Yellow and Haihe Rivers were much higher than the Redfield number, the nitrogen enrichment was still able to enhance the algae bloom in Laizhou and Bohai Bays. On the other hand, the response of algae growth to phosphorus enrichment was not thus obvious, which suggests the local phytoplankton dynamics was 2 characterized by the nitrogen limitation. Simulations also show that the nitrogen enrichment is generally accompanied by the phosphorus consumption, so a shift from nitrogen limitation to phosphorus limitation may occur if such a trend continues.

Occurrence and spatial distribution of organophosphate ester flame retardants and plasticizers in 40 rivers draining into the Bohai Sea, north China

“…Especially for the phosphorus limitation trend of Bohai Sea, not only inorganic phosphate from riverine input is important but also the organic phosphate, for instance, organophosphorus compound, may make a difference. 20 Guidance Document on Risk Assessment. 27 Risk quotients were calculated according to:…”

“…19 In the Bohai Sea, the limiting nutrients 82 of phytoplankton was changed from nitrogen in the early 1980s to nitrogen-phosphorus in the 83 late 1980s, and then to phosphorus after the 1990s. 20 Therefore, it is more worthy to estimate the 84 riverine input of organic phosphorus such as OPEs. 85…”

A Secchi Depth Algorithm Considering the Residual Error in Satellite Remote Sensing Reflectance Data

“…It is the typical semi-close sea in the world and contains the world's broadest continental shelf. The Bohai Sea is a semi-closed sea, and the mean depth is only 18 m. More than 17 rivers, like the Yellow River, annually pour 8.0 × 10 10 m 3 freshwater, and annually discharge more than 1.1 × 10 9 tons sediment and 6.1 × 10 9 mol nitrogen into the Bohai Sea [24], which make the waters very turbid and eutrophic. The Yellow Sea is deeper than the Bohai Sea, with 40 m mean depth.…”

“…Classification of water quality using Z sd -based trophic state index (TSI) proposed by Carlson[24].…”

Influences of Nutrient Sources on the Alternation of Nutrient Limitations and Phytoplankton Community in Jiaozhou Bay, Southern Yellow Sea of China

“…Over the last half-century, the external sources of nutrients for JZB have changed under the anthropogenic perturbations [20,21,30]. The diminished river runoff due to the construction of water conservancy projects, the increase in industrial and domestic wastewater discharge, the heavy aquaculture activities, together, have had great impacts on the nutrient structures in JZB over the past few decades [31].…”