The distributions of total nitrogen(TN),C/N,and nitrogen stable isotope ratio(delta~(15) N)in surface sediments are first studied in the Yellow Sea and East China Sea.The content of TN in surface sediment ranges from 0.023%to 0.33%,while C/N anddelta~(15) N are about 1.4-50.3and 4.0-16.0respectively.Significant negative correlation exists between TN and C/N,and no correlation is found between TN anddelta~(15) N or between C/N anddelta~(15) N.These relationships reflect the complexity of the nitrogen cycles in the Yellow Sea and the East China Sea,both belonging to typical continental shelf marginal sea.Then,three sediment cores collected from the southern Yellow Sea were analyzed for TN,C/N anddelta~(15) N values.And the long-term change trends of TN,C/N and delta~(15) N were subsequently rebuilt combing with 210Pb chronological study.The results indicate that the long-term changes of TN,C/N anddelta~(15) N show some periodical trends.The temporal changes of TN show similar change trends in the three sea areas,with generally increasing trends over the past 100years.And C/N trends also follow relatively similar patterns in the three sediment cores,while the average cycle ofdelta~(15) N is about 24years.Finally, the historical changes of nutrient usability in the upper water of the southern Yellow Sea over the past 200years are reconstructed,and their responses to climate change are discussed preliminarily.