Seasonal Cycling of Arsenic Species in a Stratified, Microtidal Estuary (Huon River, Tasmania)
journal contribution
posted on 2023-05-16, 15:38authored byFeatherstone, AM, Butler, ECV, O'Grady, BV
A detailed study of arsenic cycling in the Huon estuary, south-east Tasmania, was undertaken October 1996-September 1998. Arsenic species data were obtained during eight 3-monthly spatial surveys, and a time-series study at a single site in the estuary over a 7-mo period. The data have been correlated with other chemical measurements, including nutrients, salinity, and dissolved oxygen, and also with biological information about the microalgal species present In the Huon estuary, arsenic cycling is almost entirely biologically influenced. The seasonal cycle of reduced, methylated, and hydride refractory arsenic species was similar to that found in other temperate estuaries of the Northern hemisphere, with greatest production occurring during summer months. Inorganic arsenic concentrations in the Huon River were very low [As(V+III): 0.023-0.057 μg l-1], even when compared with other pristine systems. Concentrations at the seaward end of the estuary were typical of those found in unpolluted coastal seawater. The behavior of As(V+III) in the estuary was nearly conservative in all surveys except those conducted during summer (February), when significant depletion was observed at higher salinity. During these surveys, up to 60% of inorganic arsenic was apparently depleted from the water column with only a small proportion (20-25%) recycled as methylated and UV-labile arsenic species. This was particularly the case in a high salinity side-arm of the estuary, Port Cygnet. The extent of inorganic arsenic depletion correlated with cell numbers of the phytoplankton Pseudo-nitzschia. The fate of the missing inorganic arsenic is unclear, but the co-existence of Pseudo-nitzschia blooms with commercial mussel leases in Port Cygnet could provide one explanation for the loss.
History
Publication title
Estuaries
Volume
27
Pagination
18-35
ISSN
0160-8347
Department/School
School of Natural Sciences
Publisher
Estuarine Res Federation
Place of publication
Lawence
Repository Status
Restricted
Socio-economic Objectives
Measurement and assessment of estuarine water quality