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- Dastoor, Ashu, et al.
(författare)
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Arctic mercury cycling
- 2022
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Ingår i: Nature Reviews Earth & Environment. - : Springer Nature. - 2662-138X. ; 3:4, s. 270-286
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Forskningsöversikt (refereegranskat)abstract
- Anthropogenic mercury (Hg) emissions have driven marked increases in Arctic Hg levels,which are now being impacted by regional warming, with uncertain ecological consequences. This Review presents a comprehensive assessment of the present-day total Hg mass balance in the Arctic. Over 98% of atmospheric Hg is emitted outside the region and is transported to the Arctic via long-range air and ocean transport. Around two thirds of this Hg is deposited in terrestrial ecosystems, where it predominantly accumulates in soils via vegetation uptake. Rivers and coastal erosion transfer about 80 Mg year−1 of terrestrial Hg to the Arctic Ocean, in approximate balance with modelled net terrestrial Hg deposition in the region. The revised Arctic Ocean Hg mass balance suggests net atmospheric Hg deposition to the ocean and that Hg burial in inner-shelf sediments is underestimated (up to >100%), needing seasonal observations of sediment-oceanHg exchange. Terrestrial Hg mobilization pathways from soils and the cryosphere (permafrost, ice, snow and glaciers) remain uncertain. Improved soil, snowpack and glacial Hg inventories, transfer mechanisms of riverine Hg releases under accelerated glacier and soil thaw, coupled atmosphere– terrestrial modelling and monitoring of Hg in sensitive ecosystems such as fjords can help toanticipate impacts on downstream Arctic ecosystems.
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| 2. |
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| 3. |
- Parajulee, Abha, et al.
(författare)
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Comparing winter-time herbicide behavior and exports in urban, rural, and mixed-use watersheds
- 2018
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Ingår i: Environmental Science. - : Royal Society of Chemistry. - 2050-7887 .- 2050-7895. ; 20:5, s. 767-779
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Tidskriftsartikel (refereegranskat)abstract
- The presence of pesticides in streams in winter, five to six years following bans on their municipal use suggests that complicated transport behaviour, such as subsurface retention and/or accumulation of pesticides and its release during storms, could be important for understanding recovery time frames following bans or legislation that aim to reduce chemical inputs. We investigated late fall and winter dynamics of four herbicides in paired urban and rural watersheds in Toronto, Canada during rainfall and snowmelt. The range of average concentrations and loads of the sum of atrazine, metolachlor, 2,4-D and mecoprop overlapped in the two types of watersheds, with slightly higher average concentrations in the rural watershed. Relatively consistent herbicide concentration-discharge patterns (i. e. dilution) were observed in the urban sub-watersheds during rainfall, while concentration-discharge patterns were much more variable in the rural watershed. This suggests relatively uniform transport pathways across the urban sub-watersheds, compared to the rural watershed. Concentration-discharge patterns of the neutral herbicides atrazine and metolachlor were similar in both watersheds during snowmelt, though varying discharge patterns resulted in divergent timings of peak concentrations. In contrast, the acidic pesticides 2,4-D and mecoprop, which are primarily associated with urban uses, showed much more variable behavior across both watersheds and merit further investigation. Overall, this work highlights the need to consider pesticide dynamics throughout the year in order to more thoroughly assess the longterm efficacy of legislation governing their use.
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