Spatiotemporal variations of biogenic elements and sources of sedimentary organic matter in the largest oyster mariculture bay (Maowei Sea), Southwest China

Cheng Xu; Bin Yang; Solomon Felix Dan; Dong Zhang; Riquan Liao; Dongliang Lu; Ruihuan Li; Zhiming Ning; Shiqiu Peng

doi:10.1016/j.scitotenv.2020.139056

Spatiotemporal variations of biogenic elements and sources of sedimentary organic matter in the largest oyster mariculture bay (Maowei Sea), Southwest China

Sci Total Environ. 2020 Aug 15:730:139056. doi: 10.1016/j.scitotenv.2020.139056. Epub 2020 Apr 30.

Authors

Cheng Xu¹, Bin Yang², Solomon Felix Dan³, Dong Zhang⁴, Riquan Liao⁵, Dongliang Lu⁵, Ruihuan Li⁶, Zhiming Ning⁴, Shiqiu Peng⁶

Affiliations

¹ College of Chemistry and Bioengineering, Guilin University of Technology, Guilin 541000, China; Guangxi Key Laboratory of Marine Disaster in the Beibu Gulf, Beibu Gulf University, Qinzhou 535011, China.
² Guangxi Key Laboratory of Marine Disaster in the Beibu Gulf, Beibu Gulf University, Qinzhou 535011, China; Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Guangxi University, Nanning 530004, China. Electronic address: binyang@bbgu.edu.cn.
³ Guangxi Key Laboratory of Marine Disaster in the Beibu Gulf, Beibu Gulf University, Qinzhou 535011, China; Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China.
⁴ Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Guangxi University, Nanning 530004, China.
⁵ Guangxi Key Laboratory of Marine Disaster in the Beibu Gulf, Beibu Gulf University, Qinzhou 535011, China.
⁶ State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.

PMID: 32388378
DOI: 10.1016/j.scitotenv.2020.139056

Abstract

China is the largest mariculture producer in the world, but detailed information on the spatiotemporal variations of biogenic elements and sources of sedimentary organic matter (SOM) via mariculture is limited. The primary objective of this study was to assess the influence of mariculture on the origin of SOM in relation with biogenic elements and geochemical paramaters due to the importance of SOM as a potential source of nutrients and energy in coastal marine environments. Surface sediments from the Maowei Sea were collected in August (summer) and December (winter), 2016 for grain size, total organic carbon (TOC), total nitrogen (TN), organic phosphorus (OP), biogenic silica (BSi), δ¹³C and δ¹⁵N analyses. Significant correlation (p < 0.01) was observed between TOC and TN in summer and winter respectively, indicating that they have common source in both seasons. The spatiotemporal distributions of TOC, TN, OP and BSi were influenced by the sources and distribution of SOM, grain sizes and hydrodynamic conditions in the Maowei Sea. The overall ranges of δ¹³C (-26.86‰ to -23.01‰) and δ¹⁵N (2.54‰ to 9.82‰) and C/N ratio (5.83 to 18.67) showed that SOM is derived from mixed sources. The δ¹³C and δ¹⁵N-based three-end-member mixing model results revealed that >40% of the deposited SOM originates from terrestrial source during two seasons. The SOM from shellfish mariculture was seasonal, mainly deposited in the intensive mariculture areas, and its proportions were only higher than contributions from marine plankton in summer. Generally, this study indicates that shellfish biodepositions can significantly influence the cycle of carbon and other biogenic elements in the intensive mariculture areas. Nevertheless, the overall dominance of terrestrial and marine SOM suggests that the sources of SOM and factors influencing carbon cycling in the Maowei Sea do not exclusively depend on the intensity of mariculture activities.

Keywords: Biogenic elements; Maowei Sea; Mariculture; Seasonal variation; Sedimentary organic matter.

MeSH terms

Animals
Bays*
Carbon Isotopes
China
Environmental Monitoring
Geologic Sediments
Ostreidae*

Substances

Carbon Isotopes