Water Quality

Question 1

Why is water a polar compound?

Answer 1

due to an uneven charge in the two hydrogen atoms where one is partially negative and the other partially positive

Question 2

Why do polar compounds dissolve in water?

Answer 2

Due to water’s own polar nature

Question 3

What does the solubility of water range between?

Answer 3

0.1 - 100 %

Question 4

Name the three states mass in water is found? (3)

Answer 4

• dissolved
• colloidal
• suspended particulate matter

Question 5

Name 3 sources of pollutants in water resources?

Answer 5

• point source
• air pollution
• eroded soil and sediment

Question 6

What is point source contamination?

Answer 6

Contamination that can be traced to specific points of discharge from wastewater treatment plants/ factories/combined sewers

Question 7

Why is water quality crucially important?

Answer 7

• human uses e.g. drinking water, bathing

- health and integrity of aquatic ecosystems

Question 8

How is water quality assessed? (4)

Answer 8

• physical
• chemical
• biological
• aesthtic

Question 9

What do the physical properties of water include? (3)

Answer 9

• temperature
• turbidity
• suspended load

Question 10

What do the chemical properties of water include? (3)

Answer 10

• pH
• nutrients
• dissolved solids

Question 11

What do the biological properties of water include? (2)

Answer 11

• aquatic invertebrates

- E coli

Question 12

Define pH

Answer 12

a negative logarithim to the base 10 of the concentration of hydrogen ions in solution

Question 13

What is the pH range of natural stream water?

Answer 13

6 - 8.5

Question 14

What are teh effects of an increase in acidity of stream water?

Answer 14

• affects survival of fish

adult fish die and fish reproduction is affected

Question 15

What does TDS stand for?

Answer 15

total dissolved solids

Question 16

Name a few hydrological pathways of TDS? (4)

Answer 16

• Run off
• leaching into groundwater
• wet and dry deposition
• weathering of minerals along water flow pathways

Question 17

What could high TDS values indicate?

Answer 17

• occurrence of excessive soluble ions

Question 18

What is electrical conductivity?

Answer 18

• the ability of a substance to conduct electricity

Question 19

What are the units of electrical conductivity?

Answer 19

• siemens (S) per cm

Question 20

What factors affect EC?

Answer 20

• temperature (measured EC increases by 2-3% with a rise of 1 degree)

Question 21

What is the medium for conductance in water?

Answer 21

The partial charge of the water molecules as well as dissolved ions

Question 22

What is EC directly linked to?

Answer 22

• total dissolved solids (TDS)

Question 23

Define accuracy

Answer 23

agreement of measured values with the true value of a parameter of interest

Question 24

Define precision

Answer 24

closeness of multiple independent measurements to each other

Question 25

How can accuracy be ensured when taking measurements?

Answer 25

• instrument calibration

- analysis of standard reference material

Question 26

Why is temperature important in assessing water quality?

Answer 26

• affects rates pf biological and chemical processes
• survival of aquatic organisms (5 -1- degrees)
• affects solubility of gases

Question 27

Define turbidity

Answer 27

degree of clarity of water

Question 28

How is turbidity caused?

Answer 28

suspended matter (plankton and microbes) which results in absorbance or scattering of light

Question 29

What is the unit of measurement for turbidity?

Answer 29

NPT

Question 30

What is a negative impact of turbid water? (2)

Answer 30

reduces photosynthesis in water

reduces effectiveness of disinfection of water

Question 31

What defines suspended solids?

Answer 31

materials larger in size than 0.45um to be retained by a filter suspended in water

Question 32

How are suspended solids measured?

Answer 32

filter a sample through the filter, soilds retained on the filter are dried and weighed to calculate total amount

Question 33

What defines the suspended load?

Answer 33

total amount of material passing through a point over a defined time period in a stream

Question 34

What factors affect suspended load?

Answer 34

geology, vegetation, relief, rainfall intensity

Question 35

Why is dissolved oxygen an important measurement in assessing the water quality index? (2)

Answer 35

• sensitive fresh water fishes require oxic water

- low dissolved oxygen could be indicative of eutrophication

Question 36

What is the chemical formula for ammonium?

Answer 36

NH3

Question 37

Name 3 nutrients affecting water quality?

Answer 37

• nitrate (NO3)
• Ammonium (NH3)
• Phosphorus (P)

Question 38

Why is nitrate soluble in water?

Answer 38

because its a polar compound

Question 39

What are the effects of ammonium in water?

Answer 39

• very toxic to fish

Question 40

What can increase the concentration of ammonium in water?

Answer 40

A higher pH

Question 41

Where does phosphorus originate from in water?

Answer 41

Weathering of phosphate rocks (as well as agricultural fertilisers, animal wastes ad the industry)

Question 42

How can biological water quality be measured?

Answer 42

number and diversity of organisms

Question 43

Define eutrophication

Answer 43

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

Question 44

What is porosity?

Answer 44

the part of a soil volume not occupied by soil particles or organic matter