Unit 3; Energy and environmental pollution; heavy metal, AMD, thermal pollution
- Created by: Former Member
- Created on: 05-11-16 17:45
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- Heavy Metals; Acid Mine Drainage; Thermal Pollution
- Heavy Metals
- metals that are toxic to living things, inhibit enzynmes
- neurotoxins
- Lead Pb
- workers inhale dust or absorb through skin
- must wear respirators
- water sprays reduce dust
- Pb in water pipes dissolved
- phosphoric acid added to react with Pb to make insoluble lead phosphate
- Pb paint can flake and be consumed by children
- hot air paint removal guns less likely to produce vapours
- used in petrol as anti-knock agent so in exhaust fumes
- alternatives used
- workers inhale dust or absorb through skin
- Cadmium Cd
- used in batteries
- Cd drainage contaminated rice paddies in Japan causing Itai-Itai
- bone softening and kidney failure
- Cd is synergistic with Zinc and increase toxicity
- Mercury Hg
- main source is coal combustion & gold mining
- 3 Chemical forms
- Liquid Hg
- not efficiently absorbed by gut or skin but easily in lungs
- Inorganic Hg
- absorbed in gut & skin but not lipo-soluble so doesn't enter brain or cells
- Organic Hg (methyl-mercury)
- easily absorbed in gut & lungs, & liposoluble
- Liquid Hg
- Minamata disease
- mercury to methylmercury by anaerobic bacteria
- absorbed by plankton and carried along food chain to humans as liposoluble & biomagnifies
- caused muscle weakness, poor vision & speech, insanity
- Tin Sn
- Tri Butyl Tin paints used on boats as anti-fouling paint to reduce barnacle growth
- Waste Disposal
- landfills need clay/plastic lining to prevent leaching
- increase pH by adding Lime to precipitate
- phyto-remediation is using plants to treat pollution by uptaking metals
- Acid Mine Drainage
- iron sulfide reacts with H2O & O2 in disused mines which fill with water
- FeS+H2O+O2=Fe+SO4+H
- yellowboy (precipitated Fe hydroxide) increases water turbidity & clogs gills
- Effects
- reduces biodiversity
- denatures enzymes due to pH
- weakens Ca exoskeletons
- increased infection risk
- damages food chains
- osmotic changes
- heavy metal pollution worsens as better in acid
- Treatment
- collect in bunds as exits mine
- put in collection lagoon with impermable liner
- evaporate to reduce volume
- neutralise with lime
- phyto-remediation
- electrolysis
- filtration
- Thermal Pollution
- caused by hot waste water from power stations
- Effects
- cause enzyme denature
- O2 concentration reduces in warm water
- increases pollutant toxicity
- increased chemical reaction rate
- temp effects egg development & hatching dates
- cooling towers transfer heat to air
- Heavy Metals
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