Urban Water Pollution Flashcards
What is included under the definition of Urban Water
- Rivers/Streams/Brooks
- Canals
- Lakes/Ponds
- Fountains
- Water butts
- Allotments
- Gutters/Drains/Sewers
- Swales/Detention ponds
- Waste water treatment plants
- Domestic supply
Why is water security one of our greatest societal challenges?
- Globally 1 in 9 people lack access to safe water
- 2.4 billion people have no sanitation system
Why is water quality one of our greatest environmental challenges
- 90% of sewage in developing nations is not treated before discharged into water bodies
- 1/3 of global biodiversity loss is estimated to be as a result of degraded freshwater ecosystems
The UK is assumed to be a wet country, why is this not the case
- 27 Water Resource Zones (WRZs) anticipated to have a deficit of supply to demand by 2030
- Impacts of deficit most felt in London and SE
What two factors in particular are going to worsen water scarcity
- Increasing population and climate change
graph shown for 2050 for low/high population and med/high climate change
Describe atmospheric deposition as an urban water pollution source
- NH₄⁺/NO₃⁻/SO₃²⁻
- react with water in the atmosphere to form acid rain (occurs particuarly in urban areas)
What anthropogenic activities can cause urban water pollution?
- Industrial (heavy metals/chemicals/oil/plastics)
- Domestic (detergents/pharamceuticals/pet meds)
- Transport (Fuels/Antifreeze/Salts/Tyre Particles)
- Agriculuture & Horticulture (Herbicides/Pesticides/Fertilisers)
How can drainage system misconnections contribute to urban water pollution?
Through Raw sewage, Pharamceuticals and Chemicals
What is a diffuse pollution source
The release of a potential pollutant (that individually may have little impact on the water environment) but at a catchment scale can have significant effect
e.g. impermeable surface runoff into aquatic systems
What is the issue with diffuse pollution sources
Difficult to pin point and trace to source and therefore difficult to manage
What is a point pollution source?
- Any single identifiable source of pollution into the aquatic environment
- Pollutant concentrations are usually highest nearest the source and diminish in concentration with increasing distance
- E.g. Sewer pipe discharge into an aquatic system
What is the Water Metric used in the UK
EU Water Framework Directive (2000)
Using the EU Water Framework Directive (2000), in England & Wales, how many rivers achieve ‘good’ ecological status rating
How many rivers pass the chemical standards rating
- Just 14% of rivers achieve ‘good’ ecological status rating
- All river fail chemical standard ratings
- (Failings are caused by a combination of impacts from agriculutre, water industry, urban and transport activities)
What is the difference between a Category 1 and a Category 2 incident recorded by the Environmental Agency
- Category 1: incidents have a serious extensive or persistent impact on the environment, people or property
- Category 2: incidents have a lesser, yet significant, impact
Rivers/Streams/Lakes have improved in quality since the 1970s
Why is this not a very good comparision for todays waters
- The Thames was effectively dead in the 1970s
- Regularly had concentrations of led in the water
- Multiple systems where hypertropic (leakages of minerals leding to eutrophication)
Urban waste water is commonly referred to as…
…sewage
What is Sewage defined as by DEFRA 2002
A mixture of domestic waste water from baths, sinks, washing machines, and toilets, waste water from industry and rainwater run-off from roads and other surfaced areas
(many of these serious water pollution events are sewage)
UK has approx. 350,000 km combined sewage system moving X litres of waste water every day
What is X?
12 Billion
How many Water and Sewage companies exist in England
11
Who owns UK water?
> 70% of England’s water industry is owned by foregin investors (complex financial engineering structures of equity, foreign investment + pension firms)
* (March 2022 - industry debt stood at £60 billion - passed onto customers)
Untreated sewage contains high concetrations of which two inorganic compounds?
Nitrogen + Phosphorus
(taken up in the forms of NH₃-N and PO₄³⁻)
What is the consequences of high concentrations of nutrients in the waters
- Excessive primary production (eutrophication)
- Plant and invertebrate community composition changes
- Biodiversity losses (may favour some organisms over others)
What is the consequence of human pathogen in water bodies from untreated sewage-contaminated water
When bacteria from human faeces are ingested it increases the risk of significant infections including antibiotic resistant bacteria
How does antimicrobial resistance come about
1) There are lots of germs and a few which are resistant to antibotics
2) When antibiotics kill bacteria causing illness they also kill ‘good bacteria’ protecting the body from infection
3) The antibiotic-resistant bacteria grow and take over
4) Some bacteria give their antibiotic resistance to other bacteria, causing more problems (horizontal gene transfer + evolutionary mutations)
These pathogens can the be consumed by low trophic levels and passed up the food chain
What affect can pharmaceuticals have on water bodies from untreated sewage?
- Endocrine distruptors from natural and synthetic oestrogens can result in feminised fish and alternations in reproduction rates
- Impact of certain drugs on behaviours of animals
- Food web consequences
What is the impacts of plastics and micro-plastic on water bodies
- Physical entanglement & damage
- Ingested by invertebrates and fish (become full + stop eating proper nutrition leading to wasting + low growth)
- Toxin transfer via digestion
- Oxidative stress, neurotoxicity
Which certain species are paticuarly affected by microplastics and why?
- Mayfly, Caddisfly and Dragonfly
- Studies indicated different taxa consume more micro plastics more frequently
Give some examples of compounds which cause polycyclic aromatic hydrocarbons to appear in water bodies
- Paints/solvents
- Petroleum products
- Industrial additives
- Garden chemicals
- Tyre particles
What is the issue with different polycyclic aromatic hydrocarbons in water bodies
- Different additives can can run into water affecting fish and affecting communities and killing them
- Some can add to certain DNA adducts and lead to cancers etc
What is the issues with salt within water bodies
- Salt from roads is washed into water systems
- This can effect osmotically regulated animals leading to possible death
- Can have evolutionary impacts why animals adapt to more saline environments
- (there has been an upward projectory in salt useage and hence concentrations found in lakes e.g.)
What effect does the removal of riparian vegetation have on water bodies
- The removal of riparian vegetation allows direct sunlight onto water
- Aquatic organisms survive between threshold temperatures, and may have to migrate elsr where
- (especially due to warming related to climate change)
How do historic landfill sites effect water bodies
- Coastal and riverine eroision is exposing once buried toxic materials and washing them into waterways
- (erosion is increased by extreme weather events)
- Toxic materials like PAH which where in soils can leach into aquatic environments if the land has been eroded
- If concentrations are high enough it will kill certain organisms
The European directive which is devised to montior environmental health of water bodies has 5 classifications
(only 14% of England’s rivers achieve a GOOD status for ecology)
How has England water quality changed since 2016?
No improvements made since 2016
(despite UK government pledging that 75% would be a GOOD status by 2027)
* EA has confirmed lower monitoring frequency and different sites
What is a huge loop hole in UK legislation to do with sewage
A loop hole which allows water companies to discharge untreated sewage into our water ways during at after ‘exceptional circumstanges’ to avoid backup in sewage systems breaching people’s homes
Except no one actually specificied what an ‘exceptional circumstance’ was
Why are thing not improving associated with UK water bodies
- ‘catchment detachment’ not being aware of the damage being done and societies being disconnected from their water environments
- People significantly underestimating their own water usage (average use 142L per day)
A grab sample is collected from a…
…single point
A composite sample is…
…a mixture of individual samples
What is a time intergrated grab sample
A sample collected at a specific time
What is a discharge integrated grab sample
A sample when pollutant concentrations are weighted relative to the water volume (i.e. discharge)
What is a time intergrated composite sample
Samples collected across a specific period of time (i.e. across 24hrs)
(can be used to plot pollution gradients)
What vessel is used to take water samples
- Pre-risened glass or polyethylene bottles (polyethethylene bottles are safer than glass
- Pre-washed amber bottles for photoinstable determinants (stop any reactions occuring and reduce contamination)
- May use glas over plastic can cause elements like phosphate to adhere to the inside of the bottle
Why would we use gloves to collect water samples
Use gloves when collecting to reduce risk of contamination by trace organics
When testing for water quality parameter, what may we usually test for?
- Nutrients
- Organic chemicals
- physio-chemical (physical properties)
- Heavy-metals
- Inorganics
- General organics
Multiparameter probes can take multiple readings that can be downloaded when back in the lab
What features in particular may be measured?
- Colour
- Temperature
- pH
- EC
- Odour
- SO₂
- ORP
Why when measuring dissolved oxygen within water should readings be taken at the same time of day
Due to temperature changing the dissolved oxygen levels
Hypoxia is then there is <60% dissolved oxygen within water
what does this mean?
No organisms can survive
Above what% of dissolved oxygen can all organisms survive
Above the 90% mark the water can support all organisms
How can pollution relate to the biological oxygen demand?
- The Amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter under aerobic conditions at a specific temperature can increase with pollution
- (Hence can be used as an index of the degree of organic pollution in the water)
What two things may affect the measurements of biological oxygen demand in the lab?
- Aeration at collection point e.g. waterfall
- Chlorine - inhibit or kill microorganisms that decompose the organic and inorganic matter
How would you measure the biological oxygen demand in the Lab
- Measured over 5 days
- Take two samples - measure one for dissolved oxygen and incubate the other at 20±1°C for 5 days then re-test dissolved oxygen
What issues can arise when measuring dissolved oxygen?
- Sometimes by the end of the 5-day incubation period the dissolved oxygen level is zero (especially true for rivers and streams with a lot of organic pollution)
- BOD relies of measureable detection of dissolved oxygen over a specific time, therefore there must be at least 1.0mg/L of oxygen present at the end and DO must have depleted by at least 2.0mg/L during the 5 day period
What is the BOD like in polluted water?
Most polluted water samples will have a BOD much higher than the oxygen available in the BOD bottle during the incubation period
How can we overcome the problem of the dissolved oxygen being too low
- if the DO is too low it is not possible to calculate the BOD
- Since there is no way of knowing when zero is reached during the 5 day incubation period
- The sample MUST be diluted by a factor to leave at least 1mg/L (bit of trial and error)
Chemical oxygen demand can…
…give a greater indication of the total amount of organic matter within a sample
Oxidises both the biodegradable and non-biodegradable organic matter components
How is chemical oxygen demand tested?
COD is tested by chemically oxidings organic matter
This requires a strong oxidant and heat or an acid
Rhodamine is a dye which is used to mimic a solute pollutant
Why might we add Rhodamine to a water source
Use it as a proxy to trace how pollution would move through a water source
What is Fick’s First Law?
- Diffusion occurs in response to a concentration gradient
- This gradient is negative (molecules move from a high to low concentration)
- Expressed change in concentration as a change in position (the bigger the concentration gradient the steeper the line is)
- the flux (is the number of molecule moving across a given area at a given time) is proportional to the concentration gradient
- Big gradient = big diffusion = big flux
when using a sensor to detect a known pollution in field, what must we produce first?
A calibration curve
Why does raw data often look messy
Because background levels need to be extracted to make sense of readings
The emission of die into a river system to mesure diffusion will produce a what type of distribution
Gaussian distribution
Drop in concentration of dye between sites is due to diffusion
In what year did the UK Government sell off the public water utilities in England and Wales to private companies
1989
(Scotland and N.Ireland’s water remained public ownership and Welsh water has since become a not-for-profit)
