New Zealand Journal of Marine and Freshwater Research abstracts
Behaviour of dissolved silica, and estuarine/coastal mixing and exchange
processes at Tairua Harbour, New Zealand
ROBERT G. BELL
NIWA-Ecosystems
National Institute of Water & Atmospheric
Research Ltd
P. O. Box 11-115
Hamilton, New Zealand
Abstract The spatial and temporal variability of dissolved
reactive silica (DSi) and salinity in Tairua Harbour (Coromandel, New Zealand)
were investigated along with that of the riverine inputs and adjacent coastal
waters. In all surveys, covering a range of fresh water discharges and seasons,
the very high linear correlations between DSi concentration and salinity
indicated conservative behaviour, with physical dilution being the only process
having any effect on the distribution of DSi in both estuarine and coastal
waters. The tidal exchange of DSi, and hence estuarine water, with the coastal
water body was high, with around 82% of the incoming flood tide comprising
"new" ocean water. This exchange process was strongly influenced by the
quasi-periodic non-tidal alongshore current, but only weakly by variation in
river discharge and tidal range. It appears that complete mixing of fresh water
(under normal flow conditions) and riverinesolutes occurs over a relatively
narrow coastal zone (2-3 km) along this stretch of the Coromandel Peninsula.
Keywords silica; tidal exchange; mixing processes; tracers;
estuary; coastal waters; rivers; Tairua; New Zealand
PDF file of entire paper: medium quality (1060K); (scanned from paper original: notes about this process)
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