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Mercury (Hg), a neurotoxic heavy metal, is transferred to marine and terrestrial ecosystems through atmospheric transport. Recent studies have highlighted the role of vegetation uptake as a sink for atmospheric elemental mercury (Hg0) and a source of Hg to soils. However, the global magnitude of the Hg0 vegetation uptake flux is highly uncertain, with estimates ranging 1000–4000 Mg per year. To constrain this sink, we compare simulations in the chemical transport model GEOS-Chem with a compiled database of litterfall, throughfall, and flux tower measurements from 93 forested sites. The prior version of GEOS-Chem predicts median Hg0 dry deposition velocities similar to litterfall measurements from Northern hemisphere temperate and boreal forests (~0.03 cm s-1 yet it underestimates measurements from a flux tower study (0.04 cm s-1 vs. 0.07 cm s-1and Amazon litterfall (0.05 cm s-1 vs. 0.17 cm s-1). After revising the Hg0 reactivity within the dry deposition parametrization to match flux tower and Amazon measurements, GEOS-Chem displays improved agreement with the seasonality of atmospheric Hg0 observations in the Northern midlatitudes. Additionally, the modelled bias in Hg0 concentrations in South America decreases from +0.21 ng m-3 +0.05 ng m-3. We calculate a global flux of Hg0 dry deposition to land of 2276 Mg per year, approximately double previous model estimates. The Amazon rainforest contributes 29% of the total Hg0 land sink, yet continued deforestation and climate change threatens the rainforest's stability and thus its role as an important Hg sink. In an illustrative worst-case scenario where the Amazon is completely converted to savannah, GEOS-Chem predicts that an additional 283 Mg Hg per year would deposit to the ocean, where it can bioaccumulate in the marine food chain. Biosphere–atmosphere interactions thus play a crucial role in global Hg cycling and should be considered in assessments of future Hg pollution.
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This content will become publicly available on February 1, 2026
Seasonal patterns of mercury bioaccumulation in lobsters (Homarus americanus) from Maine
Mercury (Hg) pollutes marine ecosystems and accumulates in benthic species. This ecological case study investigated the temporal accumulation of Hg in American lobster (Homarus americanus; H. Milne Edwards, 1837) from coastal Maine (Casco Bay, ME, USA). We analyzed total Hg levels in legal-sized lobsters (carapace length: 8.255–12.5 cm; n = 34) collected during the early (May–July 1) or late (July 15–October) recreational harvest seasons. Morphometric data show that body size correlates with body weight (R2 = 0.76; p < 0.001), and average body sizes were similar in early and late seasons. The average chelipod size was ~7% larger in male lobsters (p < 0.02), reflecting sexual dimorphism. Hg levels in select tissues from boiled lobsters were analyzed using atomic absorption spectroscopy. Hg in ambient water was undetectable, indicating that Hg in tissues reflects bioaccumulation. Hg content correlated with the lengths (cm) and weights (g) of cephalothorax, carapace, chelipod, and hepatopancreas in both male and female lobsters. Total Hg levels in most tissues were within safe and acceptable limits for human consumption (<0.2 ppm). Compared to late-season lobsters, early-season lobsters had significantly higher Hg levels in tail (~55% increase; 0.130 ppm vs. 0.084 ppm; p < 0.05) and hepatopancreas tissues (~29% increase; 0.099 ppm vs. 0.077 ppm; p < 0.05), suggesting that seasonal factors influence Hg content (e.g., spring river runoff, lobster migration, inert biological cycles). Observed seasonal fluctuations in lobster Hg levels may inform future strategies for mitigating pollution in coastal marine ecosystems.
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- Award ID(s):
- 2000211
- PAR ID:
- 10584076
- Publisher / Repository:
- Academia Biology
- Date Published:
- Journal Name:
- Academia Biology
- Volume:
- 3
- Issue:
- 1
- ISSN:
- 2837-4010
- Subject(s) / Keyword(s):
- biomagnification, coastal marine ecology, ecotoxicology, fishery biology, methylmercury
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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