High-resolution records of the rate of carbon accumulation in the shellfish aquaculture area in Sanggou Bay and its response to human aquaculture activities

Abstract:

In this study, columnar sediments taken from the shellfish aquaculture area of Sanggou Bay in 2014 were analyzed to determine the mass fraction of total carbon (TC), total organic carbon (TOC), and total nitrogen (TN) in each layer of sediments, and to calculate the mass fraction of total inorganic carbon (TIC), marine organic carbon (Cm), shell inorganic carbon (Shell-IC), and their contribution ratios to TC. The accumulation rate (or burial flux, BF) of each component was estimated. High-resolution records of various carbon accumulation rates in sedimentary carbon pools in the last 80 years were obtained using the 210Pb dating method. The average contents of TC, TIC, TOC, Cm, and Shell-IC were 1.09%, 0.75%, 0.34%, 0.15%, and 0.06%, respectively. Results showed that TIC was the main form of TC, with a contribution ratio greater than 60% between 1960 and 2010. The mass fraction of Cm did not fluctuate significantly before 2010, but increased significantly after 2010, significantly increasing Cm/TC and TOC/TC. Shell-IC remained at a low level from the start of aquaculture activities until 2000. The carbon accumulation rate of each component responded to human marine aquaculture activities from 1960 to 2000. Due to the modification of aquaculture scale and pattern after 2000, BFCm, BFTOC, and BFTC increased significantly, BFTIC decreased, and BFshell-IC first increased and then decreased. Marine aquaculture activities in Sanggou Bay influenced the composition and accumulation rate of the carbon pool in the shellfish aquaculture area, and the carbon components responded to changes in aquaculture activities. The research results describe the effects of human aquaculture activities on the accumulation rate of sedimentary carbon pools in detail over 50 years after the start of aquaculture activities. This study also provides a reference for rational planning of aquaculture activities in continental shelf areas in the future.