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Xu Z, Lu Q, Jia D, Li S, Luo K, Su T, Chen Z, Qiu G. Significant biomagnification of methylmercury in songbird nestlings through a rice-based food web: Insights from stable mercury isotopes. JOURNAL OF HAZARDOUS MATERIALS 2024; 468:133783. [PMID: 38367440 DOI: 10.1016/j.jhazmat.2024.133783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 02/07/2024] [Accepted: 02/12/2024] [Indexed: 02/19/2024]
Abstract
To elucidate the sources and transfer of mercury (Hg) in terrestrial food chains, particularly in heavily Hg-contaminated rice paddy ecosystems, we collected rice leaves, invertebrates, and Russet Sparrow nestlings from a clear food chain and analyzed the dietary compositions and potential Hg sources using stable Hg isotopes coupled with a Bayesian isotope mixing model (BIMM). Our findings indicated that MeHg exposure is dominant through the dietary route, with caterpillars, grasshoppers, and katydids being the main prey items, while the less provisioned spiders, dragonflies, and mantises contributed the most of the Hg to nestlings. We found minimal MIF but certain MDF in this terrestrial food chain and identified two distinct MeHg sources of dietary exposure and maternal transfer. We firstly found that the dietary route contributed substantially (almost tenfold) more MeHg to the nestlings than maternal transfer. These findings offer new insights into the integration of Hg from the dietary route and maternal transfers, enhancing our understanding of fluctuating Hg exposure risk during the nestling stage. Our study suggested that Hg isotopes combined with BIMM is an effective approach for tracing Hg sources in birds and for gaining in-depth insight into the trophic transfers and biomagnification of MeHg in food chains.
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Affiliation(s)
- Zhidong Xu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Qinhui Lu
- The Key Laboratory of Environment Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Provincial Engineering Research Center of Ecological Food Innovation, School of Public Health, Guizhou Medical University, Guiyang 550025, China
| | - Dongya Jia
- School of Chemistry and Materials Science, Guizhou Normal University, Guiyang 550001, China
| | - Shenghao Li
- School of Chemistry and Materials Science, Guizhou Normal University, Guiyang 550001, China
| | - Kang Luo
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; Ailaoshan Station for Subtropical Forest Ecosystem Studies, Chinese Academy of Sciences, Jingdong 676200, China
| | - Tongping Su
- Key Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Nanning Normal University, Nanning 530001, China
| | - Zhuo Chen
- School of Chemistry and Materials Science, Guizhou Normal University, Guiyang 550001, China.
| | - Guangle Qiu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
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Luo K, Yuan W, Lu Z, Xiong Z, Lin CJ, Wang X, Feng X. Unveiling the Sources and Transfer of Mercury in Forest Bird Food Chains Using Techniques of Vivo-Nest Video Recording and Stable Isotopes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:6007-6018. [PMID: 38513264 DOI: 10.1021/acs.est.3c10972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
Knowledge gaps in mercury (Hg) biomagnification in forest birds, especially in the most species-rich tropical and subtropical forests, limit our understanding of the ecological risks of Hg deposition to forest birds. This study aimed to quantify Hg bioaccumulation and transfer in the food chains of forest birds in a subtropical montane forest using a bird diet recorded by video and stable Hg isotope signals of biological and environmental samples. Results show that inorganic mercury (IHg) does not biomagnify along food chains, whereas methylmercury (MeHg) has trophic magnification factors of 7.4-8.1 for the basal resource-invertebrate-bird food chain. The video observations and MeHg mass balance model suggest that Niltava (Niltava sundara) nestlings ingest 78% of their MeHg from forest floor invertebrates, while Flycatcher (Eumyias thalassinus) nestlings ingest 59% from emergent aquatic invertebrates (which fly onto the canopy) and 40% from canopy invertebrates. The diet of Niltava nestlings contains 40% more MeHg than that of Flycatcher nestlings, resulting in a 60% higher MeHg concentration in their feather. Hg isotopic model shows that atmospheric Hg0 is the main Hg source in the forest bird food chains and contributes >68% in most organisms. However, three categories of canopy invertebrates receive ∼50% Hg from atmospheric Hg2+. Overall, we highlight the ecological risk of MeHg exposure for understory insectivorous birds caused by atmospheric Hg0 deposition and methylation on the forest floor.
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Affiliation(s)
- Kang Luo
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Wei Yuan
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Zhiyun Lu
- Ailaoshan Station for Subtropical Forest Ecosystem Studies, Chinese Academy of Sciences, Jingdong, Yunnan 676200, China
| | - Zichun Xiong
- Ailaoshan Station for Subtropical Forest Ecosystem Studies, Chinese Academy of Sciences, Jingdong, Yunnan 676200, China
| | - Che-Jen Lin
- Center for Advances in Water and Air Quality, Lamar University, Beaumont, Texas 77710, United States
| | - Xun Wang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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Li S, Zhang F, Xu Z, Jia D, Wu G, Liu H, Li C, Liang L, Liu J, Chen Z, Qiu G. Using live videography observation and Bayesian isotope mixing model to identify food composition and dietary contribution to inorganic mercury and methylmercury intake by songbird nestlings. ENVIRONMENTAL RESEARCH 2024; 244:117902. [PMID: 38092237 DOI: 10.1016/j.envres.2023.117902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 11/30/2023] [Accepted: 12/07/2023] [Indexed: 12/17/2023]
Abstract
Mercury (Hg) exposure is increasing in terrestrial birds; however, studies on its sources are scarce. In the present study, we elucidated the food composition of green-backed tit nestlings from three urban forest parks (CPL, AHL, and LCG) using live videography observation (LVO). Furthermore, the daily dietary intakes of inorganic Hg (IHg) (MDIIHg) and methylmercury (MeHg) (MDIMeHg) were determined using the Bayesian isotope mixing model (BIMM) to uncover the nestlings' specific dietary Hg contribution. Both LVO and BIMM indicated that Lepidoptera (primarily caterpillar) constituted the primary food source for the nestlings in the three forests, accounting for approximately 60% of their diet in all three forest parks. The estimated MDI of Hg revealed that lepidopterans and spiders primarily contributed to IHg exposure, with a co-contribution ratio of 71.8%-97.7%. Unexpectedly, dietary MeHg was mostly derived from spiders; the highest contribution ratio of 93.6% was recorded at CPL, followed by another peak ratio of 92.9% at LCG. However, the dietary exposure was primarily IHg, accounting for 69.8% (AHL), 62.0% (LCG), and 61.3% (CPL) of the nestlings. Our study findings highlight the importance of dietary IHg transfer in evaluating the effects of Hg in nestlings. LVO, coupled with BIMM, is an effective tool for determining the food compositions of songbird nestlings and estimating the contribution of specific diets.
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Affiliation(s)
- Shenghao Li
- School of Chemistry and Materials Science, Guizhou Normal University, Guiyang, 550001, China
| | - Fudong Zhang
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Zhidong Xu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Dongya Jia
- School of Chemistry and Materials Science, Guizhou Normal University, Guiyang, 550001, China
| | - Gaoen Wu
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, 570228, China
| | - Hongjiang Liu
- School of Chemistry and Materials Science, Guizhou Normal University, Guiyang, 550001, China
| | - Chan Li
- School of Ecology and Environmental Science, Yunnan University, Kunming, 650091, China
| | - Longchao Liang
- School of Chemistry and Materials Science, Guizhou Normal University, Guiyang, 550001, China
| | - Jiemin Liu
- Guizhou Provincial People's Hospital, Guiyang, 550002, China
| | - Zhuo Chen
- School of Chemistry and Materials Science, Guizhou Normal University, Guiyang, 550001, China.
| | - Guangle Qiu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.
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