Sources of nitrate in Xiangshan Bay (China), as identified using nitrogen and oxygen isotopes

Yang, Zhiqian; Chen, Jianfang; Li, Hongliang; Jin, Haiyan; Gao, Shenquan; Ji, Zhongqiang; Zhu, Yong; Ran, Lihua; Zhang, Jingjing; Liao, Yibo; Bai, Youcheng

doi:10.1016/j.ecss.2018.02.019

Cited by 48 publications

(35 citation statements)

References 55 publications

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“…Throughout Zhanjiang Bay, the N/P ratios ranged from 0.2 to 30.1, with an average of 6.1, which were significantly lower than the Redfield ratio of 16 (the nutrients at this ratio are utilized by marine phytoplankton) [6]. The high PO4 3− concentrations (with a minimum value of >5 μmol•L −1 ) in the bay throughout the year suggested that N acts as a limiting nutrient in this ecosystem and that the increase in N is favorable for the proliferation of phytoplankton.…”

Section: Limiting Nutrients In Zhanjiang Baymentioning

confidence: 84%

Section: Limiting Nutrients In Zhanjiang Baymentioning

confidence: 91%

“…A salinity-based conservative mixing model was used to calculate the NO 3 − concentrations and dual-isotope values of NO 3 − from the simple physical mixing between freshwater and seawater endmembers [5,6,22,23]. The equations are as follows:…”

Section: Mixing Modelmentioning

confidence: 99%

“…Eutrophication in coastal aquatic ecosystems has prompted wide public concern owing to significantly increased nutrient inputs to coastal waters [1][2][3]. N loads to the coastal environment have been increasing as a result of intensive industrial activity, agricultural activity, and rapid urbanization in coastal areas [4][5][6][7]. Heavy nitrate (NO 3 − ) pollution has risen above acceptable levels in many areas, which greatly alters the N cycle in aquatic ecosystems, thereby endangering coastal ecosystems and biogeochemical cycles [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…The traditional, and simplest method to determine the nitrate pollution source is to identify the pollution source by investigating the land use type of the pollution area and combining it with the analysis of hydrochemical characteristics. However, due to the diversity of nitrate sources, the mixing of point and nonpoint sources and the complex physical, chemical, and biological transformation (50‰-80‰) compared to those from other sources (<25‰) [6,15]. In addition, biological processes such as assimilation and denitrification can cause isotope fractionation owing to preferential uptake of lighter isotopes ( 14 N and 16 O) [9,13].…”

Section: Introductionmentioning

confidence: 99%

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Assessing Seasonal Nitrate Contamination by Nitrate Dual Isotopes in a Monsoon-Controlled Bay with Intensive Human Activities in South China

Cao

Lao

et al. 2020

IJERPH

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Nitrate (NO3−) dual isotope analysis was performed in Zhanjiang Bay, which is a closed bay with intensive human activities in South China, to investigate seasonal changes in the main NO3− sources and their biogeochemical processes in the monsoon-controlled climate. The relatively low N/P ratios in Zhanjiang Bay suggests that nitrogen (N) is a limiting nutrient, which indicates that the increase of N is favorable for phytoplankton proliferation. However, a sufficient amount of ammonium was found in our study area owing to intensive human activities, which can support biological processes. Thus, less NO3− biological processes were found, indicating that NO3− isotopic characteristics may reveal details of the mixing from various sources. The Bayesian mixing model showed that NO3− in the upper bay originated from manure (43%), soil N (30%), N fertilizer (17%), and N precipitation (10%) during winter, which reflects the local human activities; while NO3- sources during summer were mainly N fertilizer (36%), soil N (32%), and manure (31%), indicating the source as the runoff from the upper river basin. Our results suggest that nitrate dual-isotope was very useful for tracing the main NO3− sources in the condition of the sufficient ammonium, and runoff exerted an important impact on the shift in NO3− sources between both the local source and the source from the upper river basin during the two seasons in this monsoon-controlled bay.

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Section: Limiting Nutrients In Zhanjiang Baymentioning

confidence: 84%

Section: Limiting Nutrients In Zhanjiang Baymentioning

confidence: 91%

Section: Mixing Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Assessing Seasonal Nitrate Contamination by Nitrate Dual Isotopes in a Monsoon-Controlled Bay with Intensive Human Activities in South China

Cao

Lao

et al. 2020

IJERPH

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Isotopic source identification of nitrogen pollution in the Pi River in Chengdu

Ding

Shi²,

Ouyang³

et al. 2022

Integr Envir Assess & Manag

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This study used stable isotope (δ 15 N-NO 3 − and δ 18 O-NO 3 − ) ratios, modeled by means of a Bayesian stable isotope analysis in R (SIAR) approach, to identify nitrate sources in the Pi River, which flows through the megacity Chengdu. The goal was to determine where management resources should be applied to reduce nitrogen pollution. Results revealed that NO 3 − was the primary nitrogen species throughout the study area; that it originated in manure and sewage, as well as nitrification of fertilizer and soil nitrogen; and that the nitrogen in the main stream came primarily from the tributaries. Notably, the nitrogen concentration in the tributaries exhibited no evident seasonal variations, further demonstrating that its source was intensive anthropogenic activity. Results of Bayesian model (SIAR) estimation indicated that manure and sewage were the dominant nitrate contributors in the watershed and that the nitrate concentration decreased from 54.19% to 39.57% in response to water treatment. These results empirically demonstrate that the methodology described in this work can be used effectively in catchments affected by intensive anthropogenic activity to determine where management resources should be applied to reduce nitrogen pollution.

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The optical and molecular signatures of DOM under the eutrophication status in a shallow, semi-enclosed coastal bay in southeast China

Zhao

Zhou

Pang

et al. 2021

Sci. China Earth Sci.

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Sources of nitrate in Xiangshan Bay (China), as identified using nitrogen and oxygen isotopes

Cited by 48 publications

References 55 publications

Assessing Seasonal Nitrate Contamination by Nitrate Dual Isotopes in a Monsoon-Controlled Bay with Intensive Human Activities in South China

Assessing Seasonal Nitrate Contamination by Nitrate Dual Isotopes in a Monsoon-Controlled Bay with Intensive Human Activities in South China

Isotopic source identification of nitrogen pollution in the Pi River in Chengdu

The optical and molecular signatures of DOM under the eutrophication status in a shallow, semi-enclosed coastal bay in southeast China

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