TY - JOUR
T1 - Accumulation of sulfidic sediments in a channelised inland river system, southern Australia
AU - Wong, Vanessa
AU - Cheetham, Michael Desmond
AU - Bush, Richard Thomas
AU - Sullivan, Leigh Albert
AU - Ward, Nicholas J.
PY - 2016
Y1 - 2016
N2 - Accumulation of sulfidic sediments in freshwater environments is a relatively recent phenomenon and an emerging environmental issue. In the present study, benthic sediments along short (∼250m) reaches of an inland freshwater river in south-eastern Australia were examined to determine the abundance and vertical distribution of fine-grained organic sulfidic sediments, identified by acid volatile sulfide (AVS) and chromium-reducible sulfur (SCR) contents. Sulfidic sediments (up to 404mmolkg-1 SCR) preferentially accumulated in zones immediately overlying coarse sandy bed material. Conversely, where bed material was clay or silt dominated, comparatively limited sulfidic sediment had accumulated (where AVS and SCR were not detected). This suggests that the hydraulic conductivity of the underlying bed material could play a role in the formation of sulfidic sediments and that the overlying water column is not the sole source of SO42-. Evidence suggests that accumulation of sulfidic materials occurred preferentially downstream of channel obstructions, such as submerged logs or in scour pools. However, sediment accumulation was not limited to lower-energy parts of the channel, as would be expected for fine-grained organic sediments. Evidence of reworking, burial or sulfide formation at depth highlights the dynamism of the system and its differences to many coastal systems where these sediments are commonly found.
AB - Accumulation of sulfidic sediments in freshwater environments is a relatively recent phenomenon and an emerging environmental issue. In the present study, benthic sediments along short (∼250m) reaches of an inland freshwater river in south-eastern Australia were examined to determine the abundance and vertical distribution of fine-grained organic sulfidic sediments, identified by acid volatile sulfide (AVS) and chromium-reducible sulfur (SCR) contents. Sulfidic sediments (up to 404mmolkg-1 SCR) preferentially accumulated in zones immediately overlying coarse sandy bed material. Conversely, where bed material was clay or silt dominated, comparatively limited sulfidic sediment had accumulated (where AVS and SCR were not detected). This suggests that the hydraulic conductivity of the underlying bed material could play a role in the formation of sulfidic sediments and that the overlying water column is not the sole source of SO42-. Evidence suggests that accumulation of sulfidic materials occurred preferentially downstream of channel obstructions, such as submerged logs or in scour pools. However, sediment accumulation was not limited to lower-energy parts of the channel, as would be expected for fine-grained organic sediments. Evidence of reworking, burial or sulfide formation at depth highlights the dynamism of the system and its differences to many coastal systems where these sediments are commonly found.
KW - channel morphology
KW - freshwater river
KW - organic sediments
KW - sedimentology
UR - http://www.scopus.com/inward/record.url?scp=84994174416&partnerID=8YFLogxK
U2 - 10.1071/MF15080
DO - 10.1071/MF15080
M3 - Article
AN - SCOPUS:84994174416
SN - 1323-1650
VL - 67
SP - 1655
EP - 1666
JO - Marine and Freshwater Research
JF - Marine and Freshwater Research
IS - 11
ER -