Flashcards
Air pollution from combustion processes
Cards in this deck (18)
- 1Use equations to describe the combustion of C/HC/H + O2 → CO2 + H2O
C/H + ½ O2 → CO + H2O
C/H + N2/O2 → CO + H2O + NOX
C/H + limited → CxHy + H2O
C/H (+impurities) + N2/O2 → CO + H2O + NOX + metals - 2Is the C:H ration greater for coal or natural gas?Significantly greater in coal
e.g. more carbon for every hydrogen - 3Name 6 sources of metals1) Industrial processes i.e. smelting
2) Municipal incineration
3) Gold mining (mercury, esp. Latin America)
4) Arsenic, along with copper and chromium compounds, is a common ingredient in wood preservatives
5) Lead is still widely used as an additive in petrol.
6) Coal combustion (China) - 4What are the health issues associated with heavy metals?Exposure to heavy metals has been linked with:
– developmental retardation
– various cancers
– kidney damage
– death in some instances of very high exposure
Exposure to high levels of mercury, gold, and lead has also been associated with the development of autoimmunity
Lots of evidence to support these health effects - 5Why are heavy metals toxic?• Tend to be dense and have low b./m. pts (volatile)
• Large atoms
• Combine easily with biological materials - 6What are the sources of lead poisoning?Lead poisoning remains the single most significant preventable disease associated with an environmental and occupational toxin.
The risks of lead exposure vary greatly geographically
– Bangkok, Mexico City, Jakarta: automotive exhausts
– Inner-city Chicago, Washington, D.C.:house paint
(particularly Hispanic, African-American)
Other sources are
– lead pipes in water supply systems
– exposure to industrial sources from processes such as lead mining, smelting, and coal combustion - 7What are the health issues associated with lead?• Unlike most toxins, no lower limit for health effects
• A 10 mg dl -1 increase in lead levels in the blood is associated with a 1- to 5-point decrease in the IQ of exposed children
• Several studies have found detectable learning problems in children whose blood lead levels are as low as 5-10 mg dl -1
– Industrial/heavily trafficked parts of China: 65-95% of children had blood lead >10 mg dl -1
– Other parts of China: 50%
– Urban Nigeria: 15-30% of children have >25 mg dl -1 - 8What is the single greatest source of lead emissions into the atmosphere?• ~ 90% of all lead emissions into the atmosphere are due to the use of leaded petrol
• In 1985, U.S. EPA implemented legislation to slash use of lead in petrol by > an order of magnitude in < 1 year
• Between 1976 and 1990, average blood lead levels in the U.S. population declined from 14.5 to 2.8 mg dl -1
• Even in many European countries, around half the cars still use ‘low’ lead petrol
• Increased congestion can sometimes cancel out effects of decreases in petrol content - 9What are the implications for heavy metal emissions into the atmosphere?Once in the atmosphere, metals can travel long distances
Heavy metals from urbanised parts of the world are now found in the polar regions
Implications for human and ecosystem health:
bioaccumulation - 10What are the two major sources for particulate matter?1) Human
– Combustion e.g. motor vehicles and industrial processes
2) Natural
– Wind blown dust (e.g. from Sahara)
– Volcanoes
– Sea salt - 11What is the difference between primary and secondary particulates?Primary particulates are those which are emitted directly into the atmosphere such as vehicle and industrial emissions and wind-blown dust.
Secondary particulates are formed through
chemical transformations of gas-phase species in the atmosphere
– ammonium sulphate and ammonium nitrate
– organic component - 12Define PM10 and PM2.5 particulatesPM10
– particles with a diameter < 10 mm
PM2.5
– particles with a diameter < 2.5 mm - 13State the coarse and fine fractionCoarse fraction = PM10-PM2.5
Fine fraction = PM2.5
The coarse and fine fraction can tell you something about the source of the particles
Coarse fraction is typically 30% of total in urban areas - 14State the differences in composition between PM10 and PM2.5 particulatesPM 10 : Smoke, dirt and dust from factories, farming, and roads and Mould, spores, and pollen
PM 2.5 : Organic compounds and heavy metals - 15What are the sources of PM10 and PM2.5 particulates?PM 10 : Crushing and grinding rocks and soil, then blown by wind
PM 2.5 : Driving cars, burning vegetation, smelting and processing metals
UK emissions of PM 10 have fallen in recent years: by 42% between 1990-2000 and are expected to decrease by another 28% by 2010 compared to 2000 levels. Similar decline in emissions across Europe - 16What are the 6 factors that affect how deeply particulates penetrate lungs?BELTA+
Breathing: Breathing through your mouth allows particles to travel deeper into your lungs.
Exercise: While exercising, particles can travel deeper.
Age: Older people breath less deeply so particles may not get as deep.
Lung disease: If lung diseases block the airway, particles will not travel as far.
Weather (temperature).
Other pollutants in the air (synergy). - 17What are the health implications of particulates?There is increasing evidence that particulate matter has an adverse effect on health, particularly PM 2.5
Particles with a diameter less than 10 nm can efficiently penetrate into the lungs.
Several large epidemiological studies have shown a correlation between air pollution and mortality - 18What are the EU PM directives?In the EU, concentration limits for PM 10 have been established under directive 2008/50/EC of the European Parliament
For PM 10 : annual mean value of 40 ug m-3 and 24-h limit of 50 g m-3, not to be exceeded more than 35 times a year by January 1 2010.
For PM 2.5 : Stage 1: 25 ug m-3 by 1 January 2015
Stage 2 is 20 ug m-3 by 1 January 2020
Information
- Description
- BSc Geography Atmospheric Change (Revision Topics) Flashcards on Air pollution from combustion processes, created by jimpilky on 26/05/2014.
- Created by
- jimpilky
- Views
- 18
- Rating