Water Quality Flashcards
Define water quality
Refers to the physical, chemical and biological properties of water
Most often it refers to solute load and is heavily determined by geology
EXAMPLE: water hardness = the level of calcium carbonate (CaCO3) dissolved in water
Name 4 solutes found in water
Nitrates Sulphates Calcium Iron Magnesium Silicates
Describe the pH of rivers and it’s influence
Mean pH = 6-8
pH is principally defined by catchment geology
Value may fall below 5 in storms because rainwater is naturally slightly acidic
Influence of Dissolved Oxygen content
Sustains aquatic life
Low levels occur during low flow spells as oxygen is most readily dissolved where turbulence occurs
Describe Biological Oxygen Demand
Indicates amount of organic matter present in water
Excessive demand deprives river of oxygen
Biological oxygen demand from sewage works discharges is a key indicator of pollution
Biological oxygen demand declined downstream of a pollutant source as stream organisms break down pollutants
Describe 2 indicators of water quality
Fish as they are at the top of the food chain. Healthy fish = good water quality
Abundance and diversity of aquatic organisms. Significant pollution will always impact on aquatic biology
What is acid flushing
Water stored in the soil layers do several months → first storm autumn/winter flushes it into stream →leads to low pH
Name some changing inputs into water
New industrial processes
Growing population pressures
New agricultural fertilisers
One off events like sediment from road construction, spillage of agricultural slurry
Name a method of water quality regulation
EU Nitrates Directive - Designates nitrate vulnerable zones in Scotland.
Nitrates are a potentially dangerous substance used in agricultural fertilisers and have been linked to blue baby syndrome and cancer in adults
Describe suspended sediment and it’s potential impacts
Mostly a natural process
Severe implications for drinking water quality and other hydrological concerns like reservoir design and aquatic flora and fauna
River dammed → velocity slows → Hjulstrom curve says this results in suspended sediment → reduces capacity for reservoir behind dam
Why is acid rain such a problem for north-eastern North America and Scandinavia?
(Sources of acid rain include fossil fuel burning stations and industry)
- they are close to these sources
- high rainfall → high soil acidity
- low buffering capacity
- soils heavily leached
How do rivers cope with waste?
Through degradation, dilution and dispersion
How quickly they do this depends on:
Existing pollutant load
Temperature and pH of water
Amount of water flowing
Mixing potential of river
Water flowing + mixing potential → influenced by time fo year, nature of flow and velocity and turbulence of flow
Outline the link between water quantity and precipitation
Principal input into catchment
Rainfall intensity and frequency controls amount of run off
Exception : Colorado river that flows through zones of extremely low rainfall in Utah and Arizona but lack of rainfall has no bearing on quantity of water as it is governed by Rocky Mountains
Outline the link between water quality and runoff
Route between falling as precipitation and reaching a stream affects water quality largely
Nutrient level influenced by the length of time water spends in contact with soil → overland flow likely to have lower nutrient content than throughfalm ir groundwater
Outline the link between water quality and quantity and evaporation
QUANTITY
Loss of water through evaporation and transpiration has a direct impact in amount of water reaching stream
QUALITY
Impurities in water remain behind
Build up of salts in soils (salination)
