Variability in Nutrient Inputs to Lake Erken

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Variability in Nutrient Inputs to Lake Erken
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Hypothesis

• The nutrient concentrations in the inflows to
  Lake Erken are the same, except for Norr Malma.

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Materials and Methods

• In our project we performed field and laboratory
  work. In the field we collected samples from
  different stream inflow sites.
• In the laboratory we had to prepare the samples
  for analysis by filtering some of the water.
• We analyzed our water samples for three water
  quality variables one physical (turbidity) and
  two water chemistry (phosphorus) variables.

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Sampling sites
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Turbidity

Turbidimeter
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Orthophosphorus (PO4) and Total Phosphorus
Spectrophotometer
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Results

• There is a difference in nutrient concentrations
  between sites and the biggest nutrient
  concentration is in Norr Malma. Our hypothesis
  was true according to the data we collected

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Total Phosphorus
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Ortophosphorus
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Measurements

• Only two outflows had flowing water on the dates
  we collected samples Kristineholm and Stampån.
  The other inflows Fyringen, Slumsviken and Norr
  Malma had no measurable flow on these dates.

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Total Phosphorus vs Turbidity
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Historical Data
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Discussion
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Nutrient load

• For the phosphorus budget of Lake Erken it is
  important to consider not only the phosphorus
  concentration, but also the stream discharge.
• Kristineholm has the largest phosphorus load
  (5700 ?g/s), because it is the biggest inflow.
  Stampån has phosphorus load which is only 300
  ?g/s, because it is a small inflow.

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Conculusion

• We found that phosphorus concentration was highly
  variable between the different stream inflows to
  Lake Erken.
• We showed how phosphorus concentration changes
  throughout a year with four years of historical
  data.
• We would recommend looking at more frequent
  samples collected over the full year before
  concluding that monthly samples represent the
  real phosphorus concentration.

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