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| 2. |
- Reading, M. J., et al.
(författare)
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Spatial Distribution of CO2, CH4, and N2O in the Great Barrier Reef Revealed Through High Resolution Sampling and Isotopic Analysis
- 2021
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Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 48:15
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Tidskriftsartikel (refereegranskat)abstract
- Methane (CH4) and nitrous oxide (N2O) dynamics in coastal coral reef areas are poorly understood. We measured dissolved carbon dioxide (CO2) and CH4 (with delta C-13-CO2 and delta C-13-CH4 isotope fractions) and N2O in the Great Barrier Reef (GBR) to determine spatial distributions and emissions. CO2 (379-589 mu atm) was oversaturated due to calcification and riverine sources, as indicated by depleted delta C-13-CO2 values. CH4 (1.5-13.5 nM) was also oversaturated from nearshore biogenic sources indicated by depleted delta C-13-CH4 and probable offshore aerobic production. N2O (5.5-6.6 nM) was generally undersaturated, with uptake highest near the coast. Daily CO2 emissions were 5826 +/- 1191 tonnes, with CO2 equivalent ((eq)) N2O uptake (191 +/- 44 tonnes) offsetting 3.3% of CO2 or 89% of CH4eq (214 +/- 45 tonnes) emissions based on 20-year global warming potentials. The GBR was a slight CO2 and CH4 source and N2O sink during our study. However, further work is required to constrain diurnal, seasonal, and spatial dynamics.
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| 3. |
- Reading, M. J., et al.
(författare)
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Submarine groundwater discharge drives nitrous oxide source/sink dynamics in a metropolitan estuary
- 2021
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Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590 .- 1939-5590. ; 66:5, s. 1665-1686
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Tidskriftsartikel (refereegranskat)abstract
- Coastal waterways can be significant sources of the potent greenhouse gas nitrous oxide (N2O) due to nitrogen inputs and eutrophication. Here, we quantify groundwater derived N2O inputs and atmospheric emissions within a modified urban embayment (Sydney Harbour, Australia). Overall, we found low N2O saturation (91-171%) and air-water fluxes (-2.2 to 24.6 mu mol m(-2) d(-1)). Concentrations were highest in upstream brackish areas and a commercial/industrial subembayment. Dissolved inorganic nitrogen concentrations were low and inversely correlated to N2O throughout the harbor. N2O surface water dynamics were apparently driven by saline submarine groundwater discharge, as quantified by the radioisotope tracer radon-222. Groundwater discharge was highest within the embayments and mangrove-lined upper estuary. While groundwater was a net N2O source to surface waters, two upstream sub-embayments featured groundwater N2O concentrations lower than surface water, suggesting a sink driven by surface waters recirculating in intertidal sediments. Surface-water N2O was undersaturated within one upstream embayment, likely due to N2O consumption within sediments. Contrastingly, the downstream embayments featured higher groundwater N2O and accounted for 45% +/- 21% of the groundwater N2O flux. Sydney Harbour was a net source of N2O to the atmosphere (mean 0.6 +/- 0.3 mu mol m(-2) d(-1)) with larger N2O fluxes occurring from relatively small areas. N2O emissions (expressed in CO2 equilivents) were equivalent to 17% of CO2 emission estimates from previous studies. The low N2O emissions in Sydney Harbour contrast with other modified estuaries which often emit higher N2O fluxes due to larger nitrogen inputs.
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| 4. |
- Tait, S, et al.
(författare)
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Italian Children Exposure to Bisphenol A: Biomonitoring Data from the LIFE PERSUADED Project
- 2021
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Ingår i: International journal of environmental research and public health. - : MDPI AG. - 1660-4601. ; 18:22
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Tidskriftsartikel (refereegranskat)abstract
- A human biomonitoring (HBM) study on bisphenol A (BPA) in Italian children and adolescents was performed within the LIFE PERSUADED project, considering the residing areas, sex and age. The median urinary BPA level was 7.02 µg/L, with children living in the South of Italy or in urban areas having higher levels than those residing in the North or in rural areas. Children aged 4–6 years had higher BPA levels than those aged 7–10 and 11–14 years, but no differences were detected between sexes. The exposure in Italian children was higher compared to children from other countries, but lower than the HBM guidance value (135 µg/L). The estimated daily intake was 0.17 μg/kg body weight (bw) per day, about 24-fold below the temporary Tolerable Daily Intake of 4 μg/kg bw per day established by the European Food Safety Authority. However, this threshold was exceeded in 1.44% of the enrolled children, raising concern about the overall exposure of Italian young population.
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