Studies of estuarine sediment dynamics using 137Cs from the Tjernobyl accident as a tracer

Brydsten, Lars; Jansson, Mats

doi:10.1016/0272-7714(89)90016-4

Cited by 35 publications

(25 citation statements)

References 2 publications

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“…To the east it is bounded by a dense archipelago; to the south its surface waters are open to the Bothnian Sea, while its deeper waters are confined by a threshold at 30 m depth, creating a natural border (Brydsten 1992). Water circulation in the estuary is wind driven and in spring additionally fluvial driven (Brydsten & Jansson 1989). Fluvial currents are strongest during the spring flood (April, May), which results from the snow melt and is a pulse event in the annual discharge regime (maximum river discharge: 500 m 3 s −1…”

Section: Study Area and Samplingmentioning

confidence: 99%

“…The flood plume can extend several kilo metres into the estuary and carries 70−80% of the annual river load of suspended matter (Brydsten & Jansson 1989). In 2015, the load of NO x − related to the spring flood (April, May) was 24 t, while the summer load (June− August) at normal river discharge was only 1.8 t in total.…”

Section: Study Area and Samplingmentioning

confidence: 99%

“…Par ticle retention time is <1 d in the plume but ≥1 yr in the estuary, and particle transport to the open sea only takes place via repeated cycles of resuspension− redeposition events (Brydsten & Jansson 1989). About 30% of the estuarine surface sediments are soft, consisting of 10% fine sand and 90% clay and silt (calculated from marine surface substrate data 1:100 000 © Geological Survey of Sweden, ESRI ArcGIS, ArcMap 10.3.1).…”

Section: Study Area and Samplingmentioning

confidence: 99%

“…Such accumulation of fine material reduces the permeability of the sediment drastically , Forster et al 2003 and can ultimately exclude advective pore water flow, leaving diffusion and potentially bioirrigation as the main transport mechanisms of matter into the sediment. Sandy sediments in the Öre (April) and 11 (August) profiles (weighted-average gridding, quality limit 3, non-linear colour scale) using Ocean Data View (Schlitzer 2015 Estuary are prone to clogging of pore space due to the silt-and clay-dominated riverine particle load (Forsgren & Jansson 1993) and the long particle retention time within the estuary (>1 yr; Brydsten & Jansson 1989). The large amount of suspended fine particles that enters the estuary mainly during the spring flood (Brydsten & Jansson 1989) was evident in the 60% higher proportion of fine material at N14 in April than in August.…”

Section: Estuarine Sediment Characteristics and Oxygenmentioning

confidence: 99%

“…Sandy sediments in the Öre (April) and 11 (August) profiles (weighted-average gridding, quality limit 3, non-linear colour scale) using Ocean Data View (Schlitzer 2015 Estuary are prone to clogging of pore space due to the silt-and clay-dominated riverine particle load (Forsgren & Jansson 1993) and the long particle retention time within the estuary (>1 yr; Brydsten & Jansson 1989). The large amount of suspended fine particles that enters the estuary mainly during the spring flood (Brydsten & Jansson 1989) was evident in the 60% higher proportion of fine material at N14 in April than in August. Not surprisingly, all studied estuarine sandy sediments were non-permeable and can thus be called cohesive sands.…”

Section: Estuarine Sediment Characteristics and Oxygenmentioning

confidence: 99%

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Denitrification in an oligotrophic estuary: a delayed sink for riverine nitrate

Hellemann¹,

Tallberg²,

Bartl

et al. 2017

Mar. Ecol. Prog. Ser.

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Estuaries are often seen as natural filters of riverine nitrate, but knowledge of this nitrogen sink in oligotrophic systems is limited. We measured spring and summer dinitrogen production (denitrification, anammox) in muddy and non-permeable sandy sediments of an oligotrophic estuary in the northern Baltic Sea, to estimate its function in mitigating the riverine nitrate load. Both sediment types had similar denitrification rates, and no anammox was detected. In spring at high nitrate loading, denitrification was limited by likely low availability of labile organic carbon. In summer, the average denitrification rate was ~138 μmol N m. The corresponding estuarine nitrogen removal for August was ~1.2 t, of which ~93% was removed by coupled nitrification−denitrification. Particulate matter in the estuary was mainly phytoplankton derived (> 70% in surface waters) and likely based on the riverine nitrate which was not removed by direct denitrification due to water column stratification. Subsequently settling particles served as a link between the otherwise uncoupled nitrate in surface waters and benthic nitrogen removal. We suggest that the riverine nitrate brought into the oligotrophic estuary during the spring flood is gradually, and with a time delay, removed by benthic denitrification after being temporarily 'trapped' in phytoplankton particulate matter. The oligotrophic system is not likely to face eutrophication from increasing nitrogen loading due to phosphorus limitation. In response, coupled nitrification−denitrification rates are likely to stay constant, which might increase the future export of nitrate to the open sea and decrease the estuary's function as a nitrogen sink relative to the load.

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Section: Study Area and Samplingmentioning

confidence: 99%

Section: Study Area and Samplingmentioning

confidence: 99%

Section: Study Area and Samplingmentioning

confidence: 99%