Nutrient Inputs to Estuaries from Nine Scottish East Coast Rivers; Influence of Estuarine Processes on Inputs to the North Sea

Regional evaluation of nutrient transformation and phytoplankton growth in nine river-dominated sub-tropical east Australian estuaries

“…None of the estuaries showed persistent features, such as turbidity maxima, that are commonly seen in other systems (e.g. Fisher et al 1988, Balls 1994, which reflects their well-mixed salinity structure throughout most of the year. …”

“…The use of mixing diagrams was quite popular in the 1970s and 1980s (Boyle et al 1974, Officer 1979, Fisher et al 1988, Treguer & Queguiner 1989, and many others), and although still seen in more recent literature (Balls 1994, Eyre & Twigg 1997, their popularity has waned, probably due to criticism over steady-state assumptions. If the river concentration of a dissolved conservative parameter varies on a time scale less than or equal to the flushing time of the estuary, it may show an 'apparent' non-linear distribution on a mixing plot (Loder & Reichard 1981, Officer & Lynch 1981, Cifuentes et al 1990).…”

On the Influence of the Nearbed Sediments in the Oxygen Budget of a Lagunar System: The Ria de Aveiro - Portugal

“…Denitrification, which is an inverse process by which combined nitrogen (nitrate, ammonium or organic forms) is reduced anaerobically to gaseous end products form of nitrogen (NO, N 2 O or N 2 ) by heterotrophic bacteria (Devol et al, 1997;Devol 2008, Fenel et al, 2009, Kaspar, 1982, should be, as well, considered in the nitrogen budget of a given water body, even though its effect in sediments containing ample labile organic matter is often limited by the availability of nitrate or nitrite (Fenel et al, 2009). Trimmer et al (1998) discussed the role of the bottom sediments in the N budget of the upper estuary of the Great Ouse, and showed that, although a fractional loss of riverine nutrient loads via either denitrification, primary production or sediment burial, within an estuary, seems to be, in part, related to the estuary flushing time or residence time (Balls 1994, Nixon et al 1996, estuarine sediments may also add fixed available N (primarily NH 4 + ) to the overlying water via NO 3 -and organic ammonifications. They showed, as well, that more than 90% of the total sedimentary N flux removing NO 3 -from the water column was due to N gases and the sediments of the upper estuary.…”

Spatio-Temporal Variation of Flushing Time in the Sumjin River Estuary

“…Although either flushing time equation appears to entail a straightforward steady-state calculation, the choice of freshwater discharge rate Q f can be problematic, because the river discharge is rarely in a steady state (Alber and Sheldon 1999). Some investigators use the river discharge on the actual date of field observation (Balls 1994;Eyre and Twigg 1997), some use the river discharge averaged over a number of days prior to field observation (Atkinson et al 1978), and still others use monthly or seasonally averaged flows (Pilson 1985;Lebo et al 1994). Each of these approaches results in a different estimate of the flushing time.…”