Spatial and Seasonal Variations of Sedimentary Organic Matter in a Subtropical Bay: Implication for Human Interventions

Xuan Lu, Fengxia Zhou, Fajin Chen, Qibin Lao, Qingmei Zhu, Yafei Meng and Chunqing Chen
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Xuan Lu: College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China
Fengxia Zhou: College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China
Fajin Chen: College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China
Qibin Lao: Marine Environmental Monitoring Center of Beihai, State Oceanic Administration, Beihai 536000, China
Qingmei Zhu: College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China
Yafei Meng: College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China
Chunqing Chen: College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China

IJERPH, 2020, vol. 17, issue 4, 1-20

Abstract: Elemental (total organic carbon (TOC) and total nitrogen (TN)) and stable carbon and nitrogen isotope compositions (δ 13 C and δ 15 N, respectively) in the surface sediment of Zhanjiang Bay (ZJB) in spring and summer were measured to study the spatial and seasonal changes of organic matter (OM) and assess the human-induced and environment-induced changes in the area. The OM in the surface sediment of ZJB was a mixture of terrestrial and marine sources, and was dominated by marine OM (54.9% ± 15.2%). Compared to the central ZJB, the channel and coastal ZJB areas had higher δ 13 C and δ 15 N values, higher TOC and TN concentrations, and lower TOC/TN ratios, indicating higher primary productivity and higher percentages of marine OM in the latter two subregions. Mariculture activities, sewage inputs, and dredging were responsible for these phenomena. Clear seasonal variations in OM were observed in ZJB. The average proportions of terrestrial OM in summer increased by 10.2% in the ZJB channel and 26.0% in the coastal ZJB area compared with those in spring. Heavy rainfall brought a large amount of terrestrial OM into the channel and coastal ZJB areas, leading to the increase of the terrestrial OM fraction in these two subregions in summer. In summary, anthropogenic influences had a significant influence on the spatial and seasonal variations of sedimentary OM in ZJB.

Keywords: sedimentary organic matter; stable isotopes; seasonal variations; anthropogenic influence; Zhanjiang Bay (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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