
%0 Journal Article
%A Eyre, B 
%T Nutrients in the sediments of a tropical north-eastern Australian estuary, catchment and nearshore coastal zone
%J Marine and Freshwater Research
%D 1993/12/01
%V 44
%N 6
%P 845-866
%K 
%R https://doi.org/10.1071/MF9930845
%U https://www.publish.csiro.au/paper/MF9930845 
%X The distribution, transport, accumulation, modification and seasonal variability of sediment  nutrients was studied in the Moresby River Estuary, catchment and nearshore zone.  Phosphorus was examined by using a quick and analytically simple three-stage sequential  extraction scheme that allows for natural environmental processes and differences in bio- availability. Elevated sediment phosphorus concentrations in the catchment during the wet  season reflect the application of phosphate fertilizers to the agricultural lands that dominate  the catchment. It is suggested that the dispersion and seasonal variability in concentration  and distribution of phosphorus are controlled by sedimentary processes (e.g. erosion and  transport of sediment) that are intimately linked to hydrological conditions. The physical  processes that operate on a time-scale of hours (e.g, tidal currents) dominate sediment  phosphorus concentration in the estuary and preclude chemical and biological equilibrium  from becoming established in the sediment phosphorus along the length of the estuary.  Elevated sediment total Kjeldahl nitrogen concentrations in the catchment reflect the  application of nitrogenous fertilizers (mainly urea). The nitrogen distribution patterns differ  from those of phosphorus, suggesting that different processes operate to control sediment  nitrogen and sediment phosphorus. Low phosphorus concentrations in the sediments suggest  that agricultural practices in the catchment and associated anthropogenic inputs are having  little, if any, impact on the catchment, river and estuary. 
