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The nitrate diagram for concentration vs salinity follows roughly the theoretical dilution line, this shows conservative behaviour. However the points dip slightly under the TDL at ~29 PSU which is non-conservative, but at ~35 PSU the points are along the TDL again. The nitrate concentration starts relative high in freshwater due to nitrifying bacteria and various trace anthropological inputs such as fertilizers. As water travels down the estuary the water becomes more saline and the nitrate concentration dilutes as it is entering a much larger body of water. The nitrate concentration could have dropped below the TDL due to phytoplankton utilisation.

Our phytoplankton data for stations P and O show a larger volume of phytoplankton than in stations N and Q. The stations P and O were at salinity readings 29 and 31 respectively which supports the decrease in nitrate concentration on our mixing diagram. We can therefore conclude that due to the higher phytoplankton numbers at P and O, the nitrate was depleted.

Our Silicon mixing diagram shows a similar trend in non-conservative behaviour, with silicon being removed from the water at around 25-29 PSU this correlates with the fact that at station O there is a large population of Cylindrotheca colsterium which is a diatom species and therefore takes up silicon for its test.

Our results for phosphate appear to be extreme non-conservative. At 35 PSU in our phosphate mixing diagram there is a massive spike of 3 umol/L which could be some sort of sewage outlet in the estuary inputting minerals, however we didn’t see any evidence of this our nitrate mixing diagram. It is more likely our results show this as some of our phosphate samples were compromised due to human error in the lab.

Temperature in the estuary appears to fall as salinity increases, this is what we expect as fresher water is less dense and therefore overlies the denser, more saline water. Also freshwater has come from a river which is a much lower volume than the sea and therefore heated easier.

As the salinity increases the pH also increases as freshwater is more acidic and saline water in more alkaline therefore naturally an increase in salinity would increase pH.

Winnie the Pooh discussion