Hydrogeology Lecture 2- Groundwater chemistry Flashcards
Eutrophication
Arises when groundwater sources are not managed properly
Fresh water
<1000 ppm TDS
TDS
Total dissolved solids
Amount of salt that can dissolve in water (the Dead Sea)
342g/kg
Sea water salinity in g/kg
~35g/kg
Brackish water- 0.5-30ppt
Estuaries, coastal swamps etc.
Climate change
changes water levels and water table
Capillary Pump
A capillary pump is a device that moves liquid using capillary action, which is the ability of liquid to rise or flow through narrow spaces without external force. This happens because the liquid is drawn up by the surface tension between the liquid and the material. It’s used in situations where small-scale or gravity-independent fluid movement is needed.
8 major species
Sodium, Potassium, Calcium, Chlorine, Sulphate, Nitrate and Bicarbonate
Measurables (other than chemical amounts)
Temperature, pH, Eh (reduction potential), Electrical conductivity
Units of electrical conductivity
S/m
Hydrochemical provinces
can influence properties of water
Piper diagram
Graphical representation of the chemistry of a water sample or samples, based on the electroneutrality of dissolved salts
Meq/L
Milliequivalent/L of water
Different Stiff diagrams in an area
Indicate water has flowed through different geological medias
Sampling rules:
- Bottle rinsed twice with sample water
- Taken upstream just below surface
- No air left in the bottle
- Acidified (keep cations in solution
- Cooled
To measure main species
Must acidify sample to <ph2
Causes for inaccuracy cations
- High organic contents leading to extra negative sites for cation attraction
- Large cation concentrations due to mining influences
Fractionation
Despite having the same chemical properties there is a difference in uptake between heavier and lighter isotopes, examples include evaporation or different processes of mineral interaction.
What impacts the isotropic nature of water
Pressure and temperature
