Dissolved Ion Concentrations

Question 0

Different dissolved ion concentrations: direct water from precipitation and snowmelt results in

Answer 0

A lower ion concentration, as rivers are more dilute.

Question 1

Reasons for different dissolved ion concentrations: (7)

Answer 1

Weathering, 
Rock type, 
Major cations - Ca2+, Mg2+, Na+, K+, 
Major anions - HCO3 -, SO4 2-, NO3 -, 
Vegetation,
Soils, 
Human intervention.

Question 2

Acidic waters, pH <3, tend to arise from

Answer 2

Oxidised sulfide-rich rocks, which generates sulfuric acid.

Question 3

Alkaline waters, pH 12, tend to arise from

Answer 3

Weathering of ultra mafic rocks.

Question 4

Seasonal variation: Stream discharge; (2)

Answer 4

Increased in April & Nov/Dec.

More water = more leaching of weathered material.

Question 5

Seasonal variation: Rainstorms;

Answer 5

Displace water that has been in contact with rocks for a while, results in initial increase in ion concentrations.

Question 6

Seasonal variation: Nutrient demand by vegetation;

Ammonium ion (NH4 +) -

Answer 6

Input exceeds output all year because of the breakdown of proteins from plants.

Question 7

Seasonal variation: Nutrient demand by vegetation;

Potassium & nitrate -

Answer 7

Input exceeds output in summer, but not in winter. Lower demand for the ions in winter.

In summer, plant growth results in their extraction.