Environmental evolution of coastal regions in northern Beibu Gulf, South China, based on sedimentary elemental records and carbon-nitrogen isotope composition

Elucidating the historical variation of biogenic elements and source provenance in coastal areas is crucial to better understand environmental evolution and organize ecological management. In this study, the spatiotemporal distribution of biogenic elements (carbon (C), nitrogen (N), phosphorus (P),...

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Main Authors: Jing Guo, Zihan Pan, Xiaomin Yan, Man Wu, Hengtong Qiu, Wanyi Li, Wenlong Huang, Di Wu, Baoming Xue, Zhiming Mo, Guilin Xu
Format: Article
Language:English
Published: KeAi Communications Co., Ltd. 2025-08-01
Series:International Journal of Sediment Research
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Online Access:http://www.sciencedirect.com/science/article/pii/S1001627925000381
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author Jing Guo
Zihan Pan
Xiaomin Yan
Man Wu
Hengtong Qiu
Wanyi Li
Wenlong Huang
Di Wu
Baoming Xue
Zhiming Mo
Guilin Xu
author_facet Jing Guo
Zihan Pan
Xiaomin Yan
Man Wu
Hengtong Qiu
Wanyi Li
Wenlong Huang
Di Wu
Baoming Xue
Zhiming Mo
Guilin Xu
author_sort Jing Guo
collection DOAJ
description Elucidating the historical variation of biogenic elements and source provenance in coastal areas is crucial to better understand environmental evolution and organize ecological management. In this study, the spatiotemporal distribution of biogenic elements (carbon (C), nitrogen (N), phosphorus (P), and silicon (Si)), and carbon and nitrogen isotopes (δ13C and δ15N), respectively in sediment were explored to illustrate elemental changes and determine sources of sedimentary organic matter (SOM) in the coastal regions of northern Beibu Gulf (CNBG). C, N, and P contents exhibited a general decreasing pattern from estuaries to offshore areas, probably due to terrigenous inputs and sediment textures. Since Si was mainly associated with diatoms, lower Si was attributed to the depression of phytoplankton growth by oyster beds in estuaries of Fangcheng Bay and the Maowei Sea. Based on a δ13C and δ15N three-end-member mixing model, it revealed that the average contribution of terrigenous plants and shellfish biodeposition for SOM were 56.00% and 22.39% in the intensive mariculture region (IMR), indicating that terrestrial sources and mariculture biodeposits played a prominent role as SOM sources. Additionally, according to three lead 210 (210Pb) dated sediment cores, it was found that elemental contents and elemental burial rates increased along with the coastal development after 1980s, particularly since 2006 when the Beibu Gulf Economic Zone was established. Multiple Linear Regression results showed that C and N contents and sedimentation rates were responsible for the variation of carbon burial rates during the past decades. More importantly, the significant positive relation between elemental contents and population, and gross domestic product (GDP) growth further proved a close relation between environmental evolution in the CNBG and the socioeconomic development of Guangxi Province. Moreover, the different trends of SOM source contribution for three sediment cores demonstrated the evolution characteristics among different coastal environments. The elevated δ13C and δ15N manifested the increasing contribution of marine phytoplankton (46.83%–69.33%) to SOM in Sanniang Bay recently, where frequent occurrence and decomposition of algal blooms resulted in more SOM. The dominant fraction of terrestrial sources (76.50% ± 13.27%, where ± indicates a standard deviation bound) to SOM in Lianzhou Bay implied the significant impacts of riverine inputs and fishing activities during the last century. This study indicates human activities have led to the continuous increase in nutrients, which has caused ecological risks such as algal blooms in the CNBG, thus, the mitigation of coastal eutrophication needs close attention.
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spelling doaj-art-96657331cfbd4d80bb2ba98809782e8f2025-08-20T02:44:52ZengKeAi Communications Co., Ltd.International Journal of Sediment Research1001-62792025-08-0140460061510.1016/j.ijsrc.2025.04.005Environmental evolution of coastal regions in northern Beibu Gulf, South China, based on sedimentary elemental records and carbon-nitrogen isotope compositionJing Guo0Zihan Pan1Xiaomin Yan2Man Wu3Hengtong Qiu4Wanyi Li5Wenlong Huang6Di Wu7Baoming Xue8Zhiming Mo9Guilin Xu10Key Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Nanning Normal University, Nanning 530001, China; Guangxi Beibu Gulf Intelligent Marine Ranching Engineering Research Center, Nanning Normal University, Nanning 530001, China; Guangxi Beibu Gulf Carbon Sink and Low Carbon Engineering Research Center, Guangxi Academy of Sciences, Nanning 530007, ChinaGuangxi Academy of Marine Sciences, Guangxi Academy of Sciences, Nanning 530007, ChinaKey Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Nanning Normal University, Nanning 530001, China; Guangxi Beibu Gulf Intelligent Marine Ranching Engineering Research Center, Nanning Normal University, Nanning 530001, China; Guangxi Beibu Gulf Carbon Sink and Low Carbon Engineering Research Center, Guangxi Academy of Sciences, Nanning 530007, ChinaGuangxi Academy of Marine Sciences, Guangxi Academy of Sciences, Nanning 530007, China; Guangxi Beibu Gulf Carbon Sink and Low Carbon Engineering Research Center, Guangxi Academy of Sciences, Nanning 530007, ChinaKey Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Nanning Normal University, Nanning 530001, China; Guangxi Beibu Gulf Intelligent Marine Ranching Engineering Research Center, Nanning Normal University, Nanning 530001, China; Guangxi Beibu Gulf Carbon Sink and Low Carbon Engineering Research Center, Guangxi Academy of Sciences, Nanning 530007, ChinaKey Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Nanning Normal University, Nanning 530001, China; Guangxi Beibu Gulf Intelligent Marine Ranching Engineering Research Center, Nanning Normal University, Nanning 530001, China; Guangxi Beibu Gulf Carbon Sink and Low Carbon Engineering Research Center, Guangxi Academy of Sciences, Nanning 530007, ChinaKey Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Nanning Normal University, Nanning 530001, China; Guangxi Beibu Gulf Intelligent Marine Ranching Engineering Research Center, Nanning Normal University, Nanning 530001, China; Guangxi Beibu Gulf Carbon Sink and Low Carbon Engineering Research Center, Guangxi Academy of Sciences, Nanning 530007, ChinaKey Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Nanning Normal University, Nanning 530001, China; Guangxi Beibu Gulf Intelligent Marine Ranching Engineering Research Center, Nanning Normal University, Nanning 530001, China; Guangxi Beibu Gulf Carbon Sink and Low Carbon Engineering Research Center, Guangxi Academy of Sciences, Nanning 530007, ChinaGuangdong Polytechnic of Environmental Protection Engineering, Foshan 528216, ChinaGuangxi University of Finance and Economics, Nanning 530003, China; Corresponding author.Key Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Nanning Normal University, Nanning 530001, China; Guangxi Beibu Gulf Intelligent Marine Ranching Engineering Research Center, Nanning Normal University, Nanning 530001, China; Guangxi Beibu Gulf Carbon Sink and Low Carbon Engineering Research Center, Guangxi Academy of Sciences, Nanning 530007, China; Corresponding author. Key Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Nanning Normal University, Nanning 530001, China.Elucidating the historical variation of biogenic elements and source provenance in coastal areas is crucial to better understand environmental evolution and organize ecological management. In this study, the spatiotemporal distribution of biogenic elements (carbon (C), nitrogen (N), phosphorus (P), and silicon (Si)), and carbon and nitrogen isotopes (δ13C and δ15N), respectively in sediment were explored to illustrate elemental changes and determine sources of sedimentary organic matter (SOM) in the coastal regions of northern Beibu Gulf (CNBG). C, N, and P contents exhibited a general decreasing pattern from estuaries to offshore areas, probably due to terrigenous inputs and sediment textures. Since Si was mainly associated with diatoms, lower Si was attributed to the depression of phytoplankton growth by oyster beds in estuaries of Fangcheng Bay and the Maowei Sea. Based on a δ13C and δ15N three-end-member mixing model, it revealed that the average contribution of terrigenous plants and shellfish biodeposition for SOM were 56.00% and 22.39% in the intensive mariculture region (IMR), indicating that terrestrial sources and mariculture biodeposits played a prominent role as SOM sources. Additionally, according to three lead 210 (210Pb) dated sediment cores, it was found that elemental contents and elemental burial rates increased along with the coastal development after 1980s, particularly since 2006 when the Beibu Gulf Economic Zone was established. Multiple Linear Regression results showed that C and N contents and sedimentation rates were responsible for the variation of carbon burial rates during the past decades. More importantly, the significant positive relation between elemental contents and population, and gross domestic product (GDP) growth further proved a close relation between environmental evolution in the CNBG and the socioeconomic development of Guangxi Province. Moreover, the different trends of SOM source contribution for three sediment cores demonstrated the evolution characteristics among different coastal environments. The elevated δ13C and δ15N manifested the increasing contribution of marine phytoplankton (46.83%–69.33%) to SOM in Sanniang Bay recently, where frequent occurrence and decomposition of algal blooms resulted in more SOM. The dominant fraction of terrestrial sources (76.50% ± 13.27%, where ± indicates a standard deviation bound) to SOM in Lianzhou Bay implied the significant impacts of riverine inputs and fishing activities during the last century. This study indicates human activities have led to the continuous increase in nutrients, which has caused ecological risks such as algal blooms in the CNBG, thus, the mitigation of coastal eutrophication needs close attention.http://www.sciencedirect.com/science/article/pii/S1001627925000381Environmental evolutionSedimentary elemental recordIsotope compositionAnthropogenic impactsBeibu Gulf
spellingShingle Jing Guo
Zihan Pan
Xiaomin Yan
Man Wu
Hengtong Qiu
Wanyi Li
Wenlong Huang
Di Wu
Baoming Xue
Zhiming Mo
Guilin Xu
Environmental evolution of coastal regions in northern Beibu Gulf, South China, based on sedimentary elemental records and carbon-nitrogen isotope composition
International Journal of Sediment Research
Environmental evolution
Sedimentary elemental record
Isotope composition
Anthropogenic impacts
Beibu Gulf
title Environmental evolution of coastal regions in northern Beibu Gulf, South China, based on sedimentary elemental records and carbon-nitrogen isotope composition
title_full Environmental evolution of coastal regions in northern Beibu Gulf, South China, based on sedimentary elemental records and carbon-nitrogen isotope composition
title_fullStr Environmental evolution of coastal regions in northern Beibu Gulf, South China, based on sedimentary elemental records and carbon-nitrogen isotope composition
title_full_unstemmed Environmental evolution of coastal regions in northern Beibu Gulf, South China, based on sedimentary elemental records and carbon-nitrogen isotope composition
title_short Environmental evolution of coastal regions in northern Beibu Gulf, South China, based on sedimentary elemental records and carbon-nitrogen isotope composition
title_sort environmental evolution of coastal regions in northern beibu gulf south china based on sedimentary elemental records and carbon nitrogen isotope composition
topic Environmental evolution
Sedimentary elemental record
Isotope composition
Anthropogenic impacts
Beibu Gulf
url http://www.sciencedirect.com/science/article/pii/S1001627925000381
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