Water Quality - Summary Notes

Question 1

What are the different functions of water that changes the criteria needed to be adhered to?

Answer 1

Fisheries ecosystems
Abstraction for potable supply
Abstraction for agriculture
Industrial use
Commercial harvesting of fish and shellfish for human consumption
Water sports
Special ecosystems for nature conservation

Question 2

Main points about suspended soils

Answer 2

Total suspended soils (TSS) - retained by a 2.4 micron filter (filters plankton, sand and larger silt and clay particles)
Total dissolved solids (TDS) - Pass through the same filter
Both create turbidity
High turbidity is caused by soil erosion, waste discharge, urban runoff, bottom feeders stirring up sediments or algal growth.

Question 3

How do suspended soils affect water quality?

Answer 3

Cause colour changes in water, from nearly white to red-brown or to green from algal blooms
Cause loss of diversity of aquatic organisms
Decrease oxygen levels as waters become warmer due to particles absorbing heat from sun, reduces the level of light penetrating and so reduces photosynthesis also reducing oxygen.
SS cause problems to aquatic life in numerous ways;
- clog gills
- reduce growth rates
- decrease disease resistance
- prevent egg and larval development

Question 4

How do suspended soils affect eggs and nymphs?

Answer 4

Finer particles settle to the bottom in slow-flow reaches and smother eggs of fish and aquatic insects, suffocating newly hatched insect larvae
Material infiltrating spaces between sediment clasts makes these microinhabitants unsuitable for mayfly nymphys, stonefly nymphs, caddis fly larvae and other aquatic insects

Question 5

Main points about pH

Answer 5

Most natural waters have a pH of 5-8
Areas lacking limestone (carbonate rocks) tend to have low pH water
Acid waters tend to have high levels of dissolved heavy metals, which are more easily dissolved from soils and rocks in these conditions
Low pH waters are called ‘‘soft’’
EPA considers pH to be a secondary contaminant, with an acceptable range of 6.5-8.5
Rainwater is naturally acidic because atmospheric CO2 combines with it to form carbonic acid
Unpolluted rainwater has a pH of 5.6 but human activities alter pH that can cause problems of acid deposition

Question 6

What are the ways in which waterways have altered pH?

Answer 6

Anthropogenic acidification due to the burning of sulphur enriched fossil fuel burning results in pulses of acidity during spring snowmelts and fall storms
Conifer forestry enhances acid deposition through acidic needle fall
Weathering of pyrites mediated by Thiobacillus ferroxidans in mined coal strata and mine wastes leads to acidification of drainage

Question 7

How does acidification of water form toxic substances?

Answer 7

Natural buffering of Ca and Mg carbonate rich soil and bedrock is overcome. Aluminium is leached from the soil and the water becomes toxic

Question 8

Main points about temperature

Answer 8

Depends on insolation (heating by the sun), ambient air temperature and other factors such as groundwater input and turbidity.
In temperate regions normal range is 0-30 degrees C
Tolerange of organisms to high temperature depends on;
- species
- stage of development
- acclimatisation temperature
- dissolved O2 availability
- pollution
- season
high temperatures may also be due to power stations or industrial hot water effluents

Question 9

Main points about Nitrates

Answer 9

Nitrate - NO3- Nitrite - NO2-
Nitrite forms nitrate when oxidised
Nitrate concentrations of

Question 10

Main points on Ammonia

Answer 10

Present in water as a breakdown product of proteins
Occurs partly as dissolved gas NH3 but mostly as ammonium ion NH4+
Concentrations are usually low as it is converted to nitrates (nitrification)
The un-ionised fraction of ammonia (NH3) increases with increasing pH and temperature and can be toxic to some faunal species
adverse affects are absent at concentrations of

Question 11

Main points on Phosphorus

Answer 11

Phosphorus is the main cause of water quality deterioration through eutrophication
Agriculture produces phosphorus pollution in the form of livestock effluents and mineral fertilisers (Calcium or ammonium phosphates)
The main sources of phosphorus in Europe are domestic and industrial wastewater
Recent reduction in phosphorus discharges is the result of actions taken to process domestic wastewater and reduce industrial discharges, plus improvements in the storage of animal effluents and environmentally friendlier cultivation practices.

Question 12

What is the directive called that monitors nutrient levels?

Answer 12

Urban Waste Water Treatment Directive

Question 13

According to —– classification, surface water is considered eutrophic at – –/-

Answer 13

UNECE at 25 micrograms/l

Question 14

Main points about Dissolved Oxygen

Answer 14

Dissolved O2 in water comes from the atmosphere by solution or from photosynthesis by aquatic plants and micro-organisms
At atmospheric pressure there is around 8.9mg/l of O2 at 5degreesC and 6.4mg/l of O2 at 20degreesC
Oxygen demand is the demand for oxygen by oxidisable organic matter and is used to compare waters affected by organic pollution
Biological oxygen demand - the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at a certain temperature over a specific time period. A common index is BOD5 - amount of O2 consumed within a sealed water sample in the dark over 5 days

Question 15

What are some other causes of physico-chemical water deterioration?

Answer 15

Toxic heavy metals and semi-metals (Cu, Hg,As, Sb, Pb)
Toxic soluble organic compounds (eg. those derived from fuel and libricant oils, paints and cleaning agents)
High salinity - dissolved salt concentrations (mainly chloride and sulphate salts of Na and Mg) that may be measured by electrical conductivity

Question 16

What is a cause of biological water quality deterioration?

Answer 16

pathogenic micro-organisms such as cholera (via ingestion) or toxification of water via metabolic by products ( certain algae and cyanobacteria)

Question 17

Name some common physical/chemical causes of water degradation?

Answer 17

Agricultural fertilisers - Overuse enriches water in nitrates, total ammonia and phosphate, leading to increased turbidity, eutrophication and reduction in dissolved oxygen. depending on pH and T ammonia may reach toxic levels
Sewerage - Depends on the level of treatment before dicharge. Untreated seweragge causes increases in nitrates and phosphates, eutrophication and very high biochemical oxygen demand. Infectious microbial agents may also be introduced into the water
Drainage from mines - Mine wastes and wall rocks of mine shafts and addits often have high concentrations of metal sulphides, which weather to iron hydroxides and sulphuric acid, leading to acidification and very low pH of stream waters draining from mines and mine wastes. Acid waters may also scavenge toxic heavy metals from rocks

Question 18

Why is biological measuring of water quality advantageous over chemical and physical?

Answer 18

Chemical variables vary rapidly in time and space but sampling is often based on spot samples
It is also not practical to sample all likely chemicals
Some chemicals are toxic below existing analytical detection limits
Biological sampling can detect intermittent and localised pollution and bioaccumulation may concentrate toxins to detectable levels
The ultimate consequences of environmental stress on living organisms can only be determined by examining living organisms

Question 19

What are the desirable characteristics of organisms for water quality monitoring?

Answer 19

Readily identifiable
Easily sampled
Cosmopolitan distribution
Abundant autecological data available
Economically important
Readily accumulate pollutants
Easily cultured in a lab
Low variability in a given set of habitat conditions

Question 20

Name some animals important in the measuring of water quality

Answer 20

Chironomid (midge) larvae
Caddis fly larvae
Mayfly nymph
Stonefly nymph
Nematode
Isopods

Question 21

What is RIVPACS?

Answer 21

River Invertebrate Prediciton ad Classification System
computer programme developed by Freshwater Biological Association (FBA) and the Centre for Ecology and Hydrology (CEH)
Biological monitoring tool with special emphasis on biological richness and composition of communities
Compares sites of interest with reference sites of high biological quality
Environment and fauna living there are important and both were taken into account when measuring reference sites
Uses latitude and longitude, altitude and distance, water width and depth, substrate composition, discharge category, pH, slope and air temperature statistics
Used by environmental agencies and managers for quality classification, catchment surveys, pollution investigations, minimum flow requirements and determination of conservation value

Question 22

What is SERCON?

Answer 22

System for Evaluating Rivers for Conservation
An ordinal scoring system for evaluating the conservation value of river catchments or parts of catchments
Selected reaches of streams are scored according to six attributes
- physical diversity
- naturalness
- representativness
- rarity
- species richness
- special features
A computer package is used to make calculations and provide textural and pictoral guidance on scoring
Output may be used for scoring ECS’s (evaluated catchment sections) down the length of one river, for comparing ECS’s of a similar type but in different rivers and for comparing the same ECS’s over a period of time

Question 23

What are the two types of freshwater aquatic systems?

Answer 23

Lotic - flowing, fresh (terrestrial) water

Limnic - standing water (lakes, pools)

Question 24

What are SEPA responsible for and what are their main tasks?

Answer 24

Enforcing environmental law in Scotland.
Overall objectives are conservation of flora, fauna and geological features of interest and with respect to water environments to undertake GQA’s (general water quality assessments)
main tasks are;
- licensing discharges of effluent
- enforcement of licences
- investigation and rectification of polluting incidents
-advising planners and developers on pollution avoidance
- surveying the quality and quantity of natural waters

Question 25

What are the acts and directives that allow SEPA to carry out it’s work?

Answer 25

Water Act (1989) - gives river authorities statutory duty relating to quality of controlled waters
European Water Framework Directive
Enforced by the Water Environment and Water Services (Scotland) Act 2003
via the Water Environment (controlled activities) (Scotland) Regulations 2005