Distribution Patterns of Carbon, Nitrogen and Phosphorus (TOC-TN-TP) in Surface Sediment of Chaoshan Nearshore Waters and Environmental Evaluation Analysis

Abstract

Abstract This paper presents a comprehensive analysis of the distribution characteristics and environmental assessment of total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) in the surface sediments of the Chaoshan estuary and nearshore waters from 2020 to 2021. By measuring surface sediment samples from 114 stations in Chaoshan near-shore waters, analyzing their TOC, TN and TP contents and distribution characteristics, and evaluating the pollution status by using two methods, namely, Nemero's Comprehensive Pollution Index Method and Ecotoxicity Effect, the sources of organic matter in surface sediments were initially. By comparing the content of TOC, TN, TP and the source of organic matter in the local area of the study area in the past 15 years, and summarizing the change rule, it is of great significance to comprehensively understand the current situation of surface sediment and the ecological risk of pollution in the study area. The results show:The contents of TOC, TN and TP in the surface sediments of the Chaoshan near-shore waters ranged from 0.05–1.36%, 0.006–0.210%, and 0.015–0.112%, respectively; The distribution is higher in the bay than outside the bay, higher at the mouth of the river than in the near-shore area, and gradually decreasing from the shore to the sea.;34.2% of the stations in the study area are at cleaner and above levels, 65.8% of the stations are at light to moderate pollution levels, 71.9% of the area is heavily polluted by TN and meets the criteria for Class II pollution, and 28.1% of the area is polluted by TOC and TP, which are Class I polluted༛Based on the C/N ratio to determine the source of organic matter, the source of organic matter in the surface sediments in the study area is dominated by input from marine sources, and there is a significant correlation between the various factors༛Comparison of localized surface sediments in the study area in the last 15 years revealed that TOC and TN content decreased compared to the historical period, TP content increased, C/N ratio increased compared to the historical period and was greater than 8, and the source of organic matter was dominated by a mixture of inputs from both marine and terrestrial sources.