南黄海溶解态氨基酸组成特征及DON生物可利用性研究OA北大核心CSTPCD

Bioavailable dissolved organic nitrogen(BDON)plays a vital role in the nitrogen cycle of marine eco-systems.Amino acids are an important component of BDON,which can serve as an indicator of dissolved organic nitrogen(DON)bioavailability.This study investigated the spatial distribution of hydrolysable amino acid(THAA)and bioavailability of DON in the South Yellow Sea in the spring and summer of 2021.The distributions of THAA and DON exhibited high concentrations near shore and low concentrations in offshore.The average concentrations of THAA were 0.98±0.28 and 1.11±0.34 μmol/L in the spring and summer,respectively.The average concentrations of DON were 8.17±5.06 and 5.72±2.82 μmol/L in the spring and summer,respectively.Amino acids in the South Yellow Sea mainly included serine,glycine+threonine,glutamic acid,arginine,and alanine,which accounted for 61.51%of the total amino acids in spring and 65.69%of the total amino acids in summer.The phytoplankton com-munity dominated by diatoms is an important source of amino acids in the South Yellow Sea.The outbreak of green tide caused by Ulva prolifera in summer significantly changed the composition of amino acids in the seawater.In early summer,DON in the South Yellow Sea showed high bioavailability in the area north of 35° N that supported the green tide in the late period.