Mercury speciation driven by seasonal changes in a contaminated estuarine environment

Bratkič, Arne; Ogrinc, Nives; Kotnik, Jože; Faganeli, Jadran; Žagar, Dušan; Yano, Shinichiro; Tada, Akihide; Horvat, Milena

doi:10.1016/j.envres.2013.01.004

Cited by 36 publications

(17 citation statements)

References 42 publications

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“…The levels of TotHg are similar to that found in other water basins with no local mercury input [30] but lower than in contaminated sites [31]. Our upper layer water measurements of MeHg revealed concentrations similar to what is found in oxic surface waters [32,33].…”

Section: Resultssupporting

confidence: 85%

“…Our upper layer water measurements of MeHg revealed concentrations similar to what is found in oxic surface waters [32,33]. However, the concentrations of MeHg found in deeper layers were significantly higher than what is observed even in contaminated sites [31]. MeHg/TotHg ratios in water column could vary up to about 10% in maxima [13,30] and never was found so high that those were observed in Hunnbunn in 2011.…”

Section: Resultssupporting

confidence: 72%

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Biogeochemical consequences of an oxygenated intrusion into an anoxic fjord

et al. 2014

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BackgroundThis paper is based on the studies of the biogeochemical structure of the water column in the anoxic Fjord Hunnbunn (south-eastern Norway) performed in 2009, 2011 and 2012. This Fjord is an enclosed basin of brackish water separated by a narrow and shallow outlet to the sea with a permanently anoxic layer. We show how an oxygenated intrusion could lead to both positive and negative effects on the ecosystem state in Hunnbunn due to a change in the biogeochemical structure.ResultsDuring the stratified periods in 2009 and 2012 the anoxic layer amounted to approximately 10% of the total water volume in the Fjord, while dissolved oxygen (DO) was present in 80-90% of the water. In the autumn of 2011 the water chemistry structure observed in Fjord Hunnbunn was clearly affected by a recent oxygenated intrusion defined by abnormal salinity patterns. This led to a shift of the DO boundary position to shallower depths, resulting in a thicker anoxic layer comprising approximately 40% of the total water volume, with DO present only in approximately 60% of the water. The oxygenated water intrusions led to a twofold decrease of the concentrations of hydrogen sulphide, ammonia, phosphate and silicate in the deep layers with a simultaneous increase of these nutrients and a decrease of the pH level in the surface layers. The concentrations of manganese, iron, and mercury species changed dramatically and in particular revealed a significant supply of iron and methylmercury to the water column.ConclusionsOxic water intrusions into anoxic fjords could lead not only to the flushing of the bottom anoxia, but to a dispersal of sulphidic and low oxygen conditions to the larger bottom area. The elevation of the hydrogen sulphide to the shallower layers (that can be rapidly oxidized) is accompanied by the appearance in the subsurface water of methylmercury, which is easily accumulated by organisms and can be transported to the surrounding waters, affecting the ecosystem over a larger area.

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Section: Resultssupporting

confidence: 85%

Section: Resultssupporting

confidence: 72%

Biogeochemical consequences of an oxygenated intrusion into an anoxic fjord

et al. 2014

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“…Because they connect with the terrestrial ecosystems, the coastal/marginal marine environments generally have high Hg load due to elevated atmospheric Hg deposition and watershed and coastal Hg input (Luo et al, 2010;Bratkič et al, 2013). The water column and sediments in coastal environments are hotspots for MMHg production since these regions have high nutrient concentrations and microbial activities, which are favorable factors for MMHg production (Hammerschmidt and Fitzgerald, 2004;Sunderland et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Elemental mercury (Hg(0)) in air and surface waters of the Yellow Sea during late spring and late fall 2012: Concentration, spatial-temporal distribution and air/sea flux

Wang

et al. 2015

Chemosphere

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“…It has been reported that speciation of Hg in estuarine sediments changes significantly with salinity of the overlying water column (Bratkič et al, 2013;Du Laing et al, 2009;Noh et al, 2013). Hg (weakly associated with sediment) is likely to complex with chloride of the overlying water column and probably decreases total Hg content in sediments.…”

Section: Introductionmentioning

confidence: 98%