Distribution of C/N/P stoichiometry in suspended particulate matter and surface sediment in a bay under serious anthropogenic influence: Daya Bay, China.

Abstract

The C/N/P stoichiometry of organic matter can provide useful information for better understanding of the effects of human activities on aquatic ecosystems. The Daya Bay is a semi-closed bay under serious anthropogenic influences in the southeastern China. This study investigated the contents and ratios of C, N, and P in suspended particulate matter (SPM) and surface sediment in Daya Bay during the spring of 2017. Average C/N/P ratios were 139/17/1 in the surface SPM, 129/16/1 in the bottom SPM, and 61/8/1 in the surface sediment. The C/N ratio of SPM was significantly lower in the western inner bay, suggesting that eutrophication can reduce this ratio. The N/P ratio of SPM was slightly higher in the inner bay, while no clearly distribution pattern was found in the C/P ratio of SPM. Compared with SPM, surface sediment showed significantly lower N/P and C/P ratios. The C/N, N/P, and C/P ratios and contents of total organic C, N, and P were higher in the surface sediment in the inner bay. Our results suggested that the distribution of C/N/P stoichiometry was uncoupled between SPM and surface sediment. The C/N/P stoichiometry of surface sediment can effectively reflect the regional variation of terrigenous input and the influence of nuclear power plant thermal effluent.