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- Jonsson, Sofi, 1984-
(författare)
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Unraveling the importance of solid and adsorbed phase mercury speciation for methylmercury formation, evasion and bioaccumulation
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Monomethylmercury, MeHg, is formed under anoxic conditions in waters, sediments and soils and then bioaccumulated and biomagnified in aquatic food webs, negatively effecting both human and wildlife health. It is generally accepted that precipitation of mercury, Hg, and adsorption of Hg to e.g. organic matter and mineral surfaces are important processes limiting the reactivity of Hg mobilized in the environment by natural and anthropogenic activities. However, knowledge concerning the role of different solid and adsorbed chemical forms of Hg for MeHg formation, evasion and bioaccumulation is missing. Such information is vital for the understanding of environmental processes controlling MeHg formation and bioaccumulation, as well as for predicting how changes in e.g. loading rates of atmospheric Hg and the outcome of climate change scenarios and anthropogenic land use could alter Hg concentrations in biota.In this thesis, a novel experimental approach, using isotopically enriched solid and adsorbed phases of inorganic Hg, HgII, as tracers, was developed. Using this approach, we successfully determined rates of MeHg formation from solid and adsorbed Hg species in sediment slurries and in mesocosm systems under conditions closely resembling those in field. We conclude that the solid/adsorbed phase speciation of HgII is a major controlling factor for MeHg net formation rates. Microcosm experiments revealed that newly formed MeHg was a major contributor to the evasion of MeHg from the water‒sediment system, emphasizing the importance of MeHg formation rate, rather than MeHg concentration, in the sediment for this process. From mesocosm systems, we provide experimental evidence, as well as quantitate data, for that terrestrial and atmospheric sources of HgII and MeHg are more available for methylation and bioaccumulation processes than HgII and MeHg stored and formed in sediments. This suggests that the contribution from terrestrial and atmospheric sources to the accumulation of Hg in fish may have been underestimated. As a consequence, in regions where climate change is expected to further increase land runoff, terrestrial MeHg sources may have even higher negative effects on biota than previously thought. Data and concepts presented in this thesis lay the basis for unprecedented in-depth modeling of processes in the Hg biogeochemical cycle that will improve our understanding and the predicting power on how aquatic ecosystems may respond to environmental changes or differences in loading rates for atmospheric Hg.
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| 2. |
- Gaziano, Liam, et al.
(författare)
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Mild-to-moderate kidney dysfunction and cardiovascular disease : Observational and mendelian randomization analyses
- 2022
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Ingår i: Circulation. - : Wolters Kluwer. - 0009-7322 .- 1524-4539. ; 146:20, s. 1507-1517
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: End-stage renal disease is associated with a high risk of cardiovascular events. It is unknown, however, whether mild-to-moderate kidney dysfunction is causally related to coronary heart disease (CHD) and stroke.METHODS: Observational analyses were conducted using individual-level data from 4 population data sources (Emerging Risk Factors Collaboration, EPIC-CVD [European Prospective Investigation into Cancer and Nutrition-Cardiovascular Disease Study], Million Veteran Program, and UK Biobank), comprising 648 135 participants with no history of cardiovascular disease or diabetes at baseline, yielding 42 858 and 15 693 incident CHD and stroke events, respectively, during 6.8 million person-years of follow-up. Using a genetic risk score of 218 variants for estimated glomerular filtration rate (eGFR), we conducted Mendelian randomization analyses involving 413 718 participants (25 917 CHD and 8622 strokes) in EPIC-CVD, Million Veteran Program, and UK Biobank.RESULTS: There were U-shaped observational associations of creatinine-based eGFR with CHD and stroke, with higher risk in participants with eGFR values <60 or >105 mL·min-1·1.73 m-2, compared with those with eGFR between 60 and 105 mL·min-1·1.73 m-2. Mendelian randomization analyses for CHD showed an association among participants with eGFR <60 mL·min-1·1.73 m-2, with a 14% (95% CI, 3%-27%) higher CHD risk per 5 mL·min-1·1.73 m-2 lower genetically predicted eGFR, but not for those with eGFR >105 mL·min-1·1.73 m-2. Results were not materially different after adjustment for factors associated with the eGFR genetic risk score, such as lipoprotein(a), triglycerides, hemoglobin A1c, and blood pressure. Mendelian randomization results for stroke were nonsignificant but broadly similar to those for CHD.CONCLUSIONS: In people without manifest cardiovascular disease or diabetes, mild-to-moderate kidney dysfunction is causally related to risk of CHD, highlighting the potential value of preventive approaches that preserve and modulate kidney function.
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