View in EDS

Effectively mitigated eutrophication risk by strong biological carbon pump (BCP) effect in karst reservoirs.

Saved in:
Bibliographic Details
Title: Effectively mitigated eutrophication risk by strong biological carbon pump (BCP) effect in karst reservoirs.
Authors: Zhang, Wenke1,2 (AUTHOR), Wang, Wanfa1,2 (AUTHOR) wfwang@gzu.edu.cn, Xu, Sen3 (AUTHOR), Sun, Qingqing4 (AUTHOR), Shi, Wenhong1,2 (AUTHOR), Man, Jiayi5 (AUTHOR), Yu, Shengde6 (AUTHOR), Yang, Yujing1,2 (AUTHOR), Wu, Wenxin6 (AUTHOR), Hu, Xia1,2 (AUTHOR), Wu, Qixin1,2 (AUTHOR), Wu, Pan1,2 (AUTHOR), Li, Si-Liang3 (AUTHOR)
Source: Water Research. Jun2025, Vol. 278, pN.PAG-N.PAG. 1p.
Subjects: Water management, Nitrogen isotopes, Carbon sequestration, Water purification, Carbon isotopes
Abstract: • Strong BCP effects in the epilimnion of reservoirs lead to dissolved CO 2 depletion despite high DIC concentrations in karst rivers. • Limited dissolved CO 2 and inorganic phosphorus constrain algal photosynthesis in karst reservoirs. • Eutrophication risk is lower in karst reservoirs than in non-karst reservoirs under CO 2 limitation. • Strong BCP effects in karst reservoirs positively contribute to both water quality improvement and carbon sequestration. Karst reservoirs can significantly enhance the effect of biological carbon pump (BCP), a crucial process for carbon sequestration, water purification, and eutrophication mitigation. However, the effects of BCP on the fate of carbon (C), nitrogen (N), and phosphorus (P) and its role in regulating eutrophication within river-reservoir systems, remains insufficiently understood, particularly across different geological settings. We investigated the Hongfeng Reservoir (HFR), a typical karst reservoir, analyzing water chemistry, nutrient concentrations, and stable isotopes of dissolved inorganic carbon (δ13C DIC) and nitrate (δ15N-NO 3 -) to uncover the underlying mechanisms governing the migration of biogenic elements and the process of eutrophication. Our findings reveal a strong BCP effect in the reservoirs that leads to substantial CO 2 and HCO 3 - uptake via phytoplankton photosynthesis during the warm-wet season, resulting in decreased dissolved inorganic carbon (DIC) concentrations and increased pH in the epilimnion. The δ13C DIC (−4.0 ± 0.5 ‰) values in the epilimnion relatively increased in response to phytoplankton photosynthesis that preferentially absorbs the lighter isotope of 12C. Compared with the inflow, the δ15N-NO 3 - (7.4 ± 0.2 ‰) in the epilimnion of the reservoir is significantly depleted, with the water predominantly aerobic or oxygen-supersaturated. This suggests that nitrification is the dominant process during the warm-wet season. The high NO 3 - concentrations (44.3 ± 10.1 μmol/L) indicate a sufficient N supply for biological uptake. The strong BCP effects in the epilimnion convert substantial amounts of DCO 2 and nutrients into autochthonous organic matter. The resulting increase in pH further reduces the availability of DCO 2. Furthermore, BCP-induced calcium carbonate precipitation enhances P removal through co-precipitation, thereby accelerating nutrient depletion and carbon sequestration, which collectively contribute to the mitigation of eutrophication risks. To assess the broader applicability of these findings, we analyzed data from 129 lakes and reservoirs globally. Our results show that karst reservoirs, with their strong BCP effect, exhibit an average Carlson trophic status index (CTSI) 9.8 % lower than non-karst reservoirs, indicating a reduced risk of eutrophication. These insights offer valuable implications for the management of water resources in karstic reservoirs globally. [ABSTRACT FROM AUTHOR]
Copyright of Water Research is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Engineering Source
Description
Abstract:• Strong BCP effects in the epilimnion of reservoirs lead to dissolved CO 2 depletion despite high DIC concentrations in karst rivers. • Limited dissolved CO 2 and inorganic phosphorus constrain algal photosynthesis in karst reservoirs. • Eutrophication risk is lower in karst reservoirs than in non-karst reservoirs under CO 2 limitation. • Strong BCP effects in karst reservoirs positively contribute to both water quality improvement and carbon sequestration. Karst reservoirs can significantly enhance the effect of biological carbon pump (BCP), a crucial process for carbon sequestration, water purification, and eutrophication mitigation. However, the effects of BCP on the fate of carbon (C), nitrogen (N), and phosphorus (P) and its role in regulating eutrophication within river-reservoir systems, remains insufficiently understood, particularly across different geological settings. We investigated the Hongfeng Reservoir (HFR), a typical karst reservoir, analyzing water chemistry, nutrient concentrations, and stable isotopes of dissolved inorganic carbon (δ13C DIC) and nitrate (δ15N-NO 3 -) to uncover the underlying mechanisms governing the migration of biogenic elements and the process of eutrophication. Our findings reveal a strong BCP effect in the reservoirs that leads to substantial CO 2 and HCO 3 - uptake via phytoplankton photosynthesis during the warm-wet season, resulting in decreased dissolved inorganic carbon (DIC) concentrations and increased pH in the epilimnion. The δ13C DIC (−4.0 ± 0.5 ‰) values in the epilimnion relatively increased in response to phytoplankton photosynthesis that preferentially absorbs the lighter isotope of 12C. Compared with the inflow, the δ15N-NO 3 - (7.4 ± 0.2 ‰) in the epilimnion of the reservoir is significantly depleted, with the water predominantly aerobic or oxygen-supersaturated. This suggests that nitrification is the dominant process during the warm-wet season. The high NO 3 - concentrations (44.3 ± 10.1 μmol/L) indicate a sufficient N supply for biological uptake. The strong BCP effects in the epilimnion convert substantial amounts of DCO 2 and nutrients into autochthonous organic matter. The resulting increase in pH further reduces the availability of DCO 2. Furthermore, BCP-induced calcium carbonate precipitation enhances P removal through co-precipitation, thereby accelerating nutrient depletion and carbon sequestration, which collectively contribute to the mitigation of eutrophication risks. To assess the broader applicability of these findings, we analyzed data from 129 lakes and reservoirs globally. Our results show that karst reservoirs, with their strong BCP effect, exhibit an average Carlson trophic status index (CTSI) 9.8 % lower than non-karst reservoirs, indicating a reduced risk of eutrophication. These insights offer valuable implications for the management of water resources in karstic reservoirs globally. [ABSTRACT FROM AUTHOR]
ISSN:00431354
DOI:10.1016/j.watres.2025.123395