Week 3 - Chemical processes in estuaries Flashcards
(23 cards)
What is the behavior of Fluorine in estuaries?
Conservative with higher concentration in seawater
Chlorinity is what salinity was called, with salinity being a measure of chloride ions.
What is the classification of Iron in estuaries?
Non conservative
Loss of Fe from solution in the upper part of the estuary is due to coagulation of colloidal Fe iii.
What is the main form of Iron lost in the Cape Fear Estuary?
Fe iii
Concentration of Fe ii can be high, stabilized by ligands.
How does the concentration of Fe ii change with salinity?
Decreases with increasing salinity
Loss of ligands via flocculation and increased ionic strength contribute to this change.
What type of behavior can dissolved silicon show in estuaries?
Both conservative and non conservative behavior
Which estuary shows conservative behavior of dissolved silicon in March?
Danshuei estuary
What is observed in the Elbe estuary regarding dissolved silicon?
Evidence for removal of dissolved silicon in early autumn due to diatom uptake
What promotes diatom blooms in Charlotte Harbour?
High levels of phosphate delivered by the Peace River
What happens to dissolved silicon if the estuarine residence time is short?
Rapid replenishment of dissolved silicon used by diatoms
What source of silicon is significant in Narragansett Bay during spring?
Salt marshes (remineralization of biogenic silicon)
What are other sources of dissolved silicon in estuaries?
Desorption from resuspended sediments
Anthropogenic inputs are not usually significant.
How does dissolved silicon behave in the Changjiang (Yangtze) estuary?
Shows conservative behavior but with diatoms preferentially utilizing lighter isotopes
What can Si isotopes be used to study?
Nutrient utilization and remineralization of biogenic silicon
What factors affect the behavior of dissolved silicon in estuaries?
Rate of biological uptake, residence time of water, turbidity, particle loading
What type of cycling does Manganese undergo in estuaries?
Intensive cycling linked to changes in redox conditions
What happens to Mn iv in anoxic sediments?
Reduced to Mn ii which is soluble
What is the maximum concentration of dissolved Mn often seen at?
Intermediate salinities
What occurs when Mn(II) is transported into an oxidizing environment?
Converted to MnO2, which is insoluble and precipitates
What is the main freshwater input to the Tamar estuary?
Approximately 50% to Plymouth S
What are the characteristics of the upper and lower estuary of the Tamar?
Upper: tidal mudflats and reed beds; Lower: Plymouth, dockyards, military port, mudflats, rocky shore
What type of variability was observed in the estuarine mixing of Tamar?
Large seasonal variability due to runoff residence times and point sources
What behavior does Nitrate show in the Tamar estuary?
Conservative behavior
What is the general trend of Phosphate concentrations in comparison to Nitrogen?
Very low concentrations in comparison to Nitrogen
