Biogenic Silica and Organic Carbon Records in Zhoushan Coastal Sea over the Past One Hundred Years and Their Environmental Indications

Hao Xu; Shangwei Jiang; Jialin Li; Ruiliang Pu; Jia Wang; Wanghai Jin; Longbin Sha; Dongling Li

doi:10.3390/ijerph17113890

Biogenic Silica and Organic Carbon Records in Zhoushan Coastal Sea over the Past One Hundred Years and Their Environmental Indications

Int J Environ Res Public Health. 2020 May 30;17(11):3890. doi: 10.3390/ijerph17113890.

Authors

Hao Xu^{1

2}, Shangwei Jiang¹, Jialin Li^{1

2}, Ruiliang Pu³, Jia Wang¹, Wanghai Jin¹, Longbin Sha^{1

2}, Dongling Li^{1

2}

Affiliations

¹ Department of Geography and Spatial Information Techniques, Ningbo University, Ningbo 315211, China.
² Institute of East China Sea, Ningbo University, Ningbo 315211, China.
³ School of Geosciences, University of South Florida, Tampa, FL 33620, USA.

Abstract

The influence of terrestrial and marine input has dramatically changed eutrophication in coastal seas over the past 100 years. In this study, Zhoushan coastal sea (ZCS) is taken as a study area. We studied ZCS as it is a sink of the temporal and spatial variation of primary productivity, dominant species of algae, and the variation of provenance in this area over the past 100 years. We performed analysis using three sediment cores and the carbon and silicon deposition records. The analysis results demonstrate that: (1) The primary productivity in the northern area of the ZCS close to the Yangtze Estuary was the highest comparatively, but it declined slightly before 2010. The primary productivity in the southern area had an increasing trend over the past 100 years. The value of total organic carbon (TOC) in the northern area was relatively high, with an average value of 0.532% over the past 100 years, with a decreasing trend in recent years. On the contrary, TOC in the southern area was relatively low, but it was increased dramatically after 1995. (2) Diatom might play an important role in the variations. The biogenic silica (BSi) and TOC in the northern area showed a synchronous declining trend, while the BSi/TOC ratio did not change significantly. This indicates the algae population structure in this area was relatively stable over the past 100 years. The BSi/TOC ratio decreased continuously in the southern area, indicating that the dominance of diatoms was decreasing continuously. (3) The variation of diatom dominance in this area might have a great relationship with the change of nutrients' provenance. A mean value of stable carbon isotope (δ¹³C) in the north of Zhoushan was -23.46‱, indicating that the terrestrial-source input was the highest. (4) The change of provenance in the study area was quite different. This illustrates that the terrestrial input impacted the largest area of ZCS while marine input became dominant in the offshore area.

Keywords: Zhoushan coastal sea; biogenic silica; organic carbon; provenance; sedimentary record.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Carbon / analysis*
China
Environmental Monitoring*
Estuaries
Geologic Sediments*
Humans
Silicon Dioxide / analysis

Substances

Carbon
Silicon Dioxide