Water Quality Flashcards
Why is water a polar compound?
due to an uneven charge in the two hydrogen atoms where one is partially negative and the other partially positive
Why do polar compounds dissolve in water?
Due to water’s own polar nature
What does the solubility of water range between?
0.1 - 100 %
Name the three states mass in water is found? (3)
- dissolved
- colloidal
- suspended particulate matter
Name 3 sources of pollutants in water resources?
- point source
- air pollution
- eroded soil and sediment
What is point source contamination?
Contamination that can be traced to specific points of discharge from wastewater treatment plants/ factories/combined sewers
Why is water quality crucially important?
- human uses e.g. drinking water, bathing
- health and integrity of aquatic ecosystems
How is water quality assessed? (4)
- physical
- chemical
- biological
- aesthtic
What do the physical properties of water include? (3)
- temperature
- turbidity
- suspended load
What do the chemical properties of water include? (3)
- pH
- nutrients
- dissolved solids
What do the biological properties of water include? (2)
- aquatic invertebrates
- E coli
Define pH
a negative logarithim to the base 10 of the concentration of hydrogen ions in solution
What is the pH range of natural stream water?
6 - 8.5
What are teh effects of an increase in acidity of stream water?
- affects survival of fish
adult fish die and fish reproduction is affected
What does TDS stand for?
total dissolved solids
Name a few hydrological pathways of TDS? (4)
- Run off
- leaching into groundwater
- wet and dry deposition
- weathering of minerals along water flow pathways
What could high TDS values indicate?
- occurrence of excessive soluble ions
What is electrical conductivity?
- the ability of a substance to conduct electricity
What are the units of electrical conductivity?
- siemens (S) per cm
What factors affect EC?
- temperature (measured EC increases by 2-3% with a rise of 1 degree)
What is the medium for conductance in water?
The partial charge of the water molecules as well as dissolved ions
What is EC directly linked to?
- total dissolved solids (TDS)
Define accuracy
agreement of measured values with the true value of a parameter of interest
Define precision
closeness of multiple independent measurements to each other
How can accuracy be ensured when taking measurements?
- instrument calibration
- analysis of standard reference material
Why is temperature important in assessing water quality?
- affects rates pf biological and chemical processes
- survival of aquatic organisms (5 -1- degrees)
- affects solubility of gases
Define turbidity
degree of clarity of water
How is turbidity caused?
suspended matter (plankton and microbes) which results in absorbance or scattering of light
What is the unit of measurement for turbidity?
NPT
What is a negative impact of turbid water? (2)
reduces photosynthesis in water
reduces effectiveness of disinfection of water
What defines suspended solids?
materials larger in size than 0.45um to be retained by a filter suspended in water
How are suspended solids measured?
filter a sample through the filter, soilds retained on the filter are dried and weighed to calculate total amount
What defines the suspended load?
total amount of material passing through a point over a defined time period in a stream
What factors affect suspended load?
geology, vegetation, relief, rainfall intensity
Why is dissolved oxygen an important measurement in assessing the water quality index? (2)
- sensitive fresh water fishes require oxic water
- low dissolved oxygen could be indicative of eutrophication
What is the chemical formula for ammonium?
NH3
Name 3 nutrients affecting water quality?
- nitrate (NO3)
- Ammonium (NH3)
- Phosphorus (P)
Why is nitrate soluble in water?
because its a polar compound
What are the effects of ammonium in water?
- very toxic to fish
What can increase the concentration of ammonium in water?
A higher pH
Where does phosphorus originate from in water?
Weathering of phosphate rocks (as well as agricultural fertilisers, animal wastes ad the industry)
How can biological water quality be measured?
number and diversity of organisms
Define eutrophication
an excessive richness of nutrients in a body of water due to frequent run off from the land causing a dense growth of plant life, resulting in the depletion of dissolved oxygen
What is porosity?
the part of a soil volume not occupied by soil particles or organic matter
