11: Air pollution and sulfur dioxide

Human Uses Of mercury

Manufacture of weed killers Painis Medicine Thermometer - elemental or inoganic mercury can be transformed by bacteria into organic mercury (methyl mercury) -mercury appose to be toxic to most organism but selenium is believed to reduce toxic effects.

Mnitoring air quality pg 154

Victorian environmental protection Authority (EPA , agency is american) Monitors air quality in two victorian regions: • Melbourne-geelong (port phillip region) • Latrobe valley airsheds

Syngerstic effect

: an interaction between two or more individual compounds that produces an effect upon the body (or an organism) GREATER than either of the substances alone would have been produced.

Air pollution

Introduction of chemicals, particulate matter or biological materials that cause harm or discomfort to human e.g. the use of health system Air and the pollution and the weather Weather conditions can affect the amount of pollution in the air: • wind • Temperature • Air pressure • Cloud cover • Fog, dew and frost • Precipitation (rain, snow, hail) (acid rain) -> runoff

Mercury

Mercury, or quicksilver are known in ancient times in hydroargyos, hence it's chemical symbol 'Hg'. Mercury is the only metal that is liquid at room temperature and pressure. Mercury is an extremely rare element, but occurs in deposit throughout the world mardy or annabar (or morcuric sulphide)

Organic mercury

Methyl mercury is fat soluble (and therefore insoluble in water) but found in waterways and bioaccumulates. Organic mercury compounds, sometimes called organmercurials are those containing bonds between mercury and carbon (e.g. methylmercury, dimethylmercury and methylmercury chloride) Mercury bond in two stages - is persistent, cannot be broken down into a less toxic element Hg+- elemental mercury is more toxic as a vapour Hg2+ - organic mercury can be 30 times more toxic (methyl mercury)

Mercury's presence in the environment:

Occurs naturally- in soil, coal, trees, water, atmosphere (volcanoes, forest, ocean surface.) Anthropgenic: burning coals ,metal smelters industrial waste and water system

Mercury Effects on Humans

Poisoning results from: - Inhalation of the vapour - Absorption of mercury through the skin - Ingestion of soluble compounds EG/ consuming marine organism Hg is odourless, invisible and accumulates in the meat of fish Mercury acts as a neurotoxin interfering with, and causing damage to the brain, kidney, liver, and CNS (signal gets bounced around when the receptors are inhibited in the axons.)

EPA monitoring

Seven pollutants • Cox • Og (photochemical oxidants) • No2 • So2 • Pb • Pm10 (particulate matter and the size of it -10) • Visibility reducing particles These are stated in te state environmental protection policy 1981 The AQIP (air quality improvement plan) uses an integrated approach to improving air quality using the policies and program.

Elemental mercury

Silver in colour,stable, fat-soluble and bioaccumulates Vapourise easily and can be absorbed dermely

Anthropogenic source

human made sources

Future of Hg, Transport and sinks

Future - Reducing or prevent the use of Hg - Safe, disposable of waste containing Hg Transport - Methyl mercury acts as a gas in the atmosphere. Can evaporate from soil and water - Mercury chloride acts as a particle in the atmosphere, deposited by rain Sinks: - Atmosphere, soil, water, fish (organism)

Sulphur dioxide Impacts on Human Health pg 150

• Inhaled-dissolves with moisture on the lining of the lungs and nose, burning the mucous and membrane • Chronic (long term) exposure lead to respiratory problems and heart disease • London 1950 smog presentation. Small ash particles and water in the atmosphere can act in a synergistic way with SO2, causing the formation of sulphuric acid to occur much faster than if they are not present.

Air pollutants are emitted from a wide variety of sources, including

• Mobile sources (e.g. motor vehicles and ships) • Industrial sources (eg. Manufacturing, power station) • Domestic, comerical and rural sources (individual sources that have a wide impact on air quality, but are too small to indetify as stationary sources, eg. Backyard incinerators, lawnmowers, cooking appliances) • Natural sources (eg. Organic compounds from vegetation and soils, particles associated with wind blown dust, pollen and sea salt) • Dispersion patterns are dependent on weather and geography • Primary pollutants can form secondary polluatnts by undergoing cheimcal and photochemcial reactions. See fig1.1 pg. 159 • Motor vechilce emissions are the largest contribyto to air poll

Ai quality Human and environmental health effects

• Nusiance effect (e.g. decreased visiblity) • Acute toxic effect (e.g. eye irritations, increased susceptibility to infection, reduced respiratory/pulmonary function) • Chronic health effects (e.g. mutagenic and carcinogenic actions) • Environmental effects (e.g. material soiling, vegetation damage and corrosion)

Secondary Pollutant

A secondary pollutant is not directly emitted as such, but forms when other pollutants (primary pollutants) react in the atmosphere.

Inorganic mercury

Water soluble salts (e.g. mercuric chloride) Inorganic mercury is converted to methyl mercury by bacteria

Reaction in the atmosphere (Sulphur dioxide)

The atmospheric reactions of SO2 are very complex and proceed through three different pathways to the sulphate ion (SO42) The ultimate fate of all sulphur in the atmosphere is to be oxidised to the sulphate ion, usually as sulphuric acid (H2SO2) So in summary SO2 is controversial in the atmosphere, by a series of reactions, to sulphuric acid

Mercury's danger in the environment

The exposure of hg that has settled in the environment has been argued to be low, however dredging up sediments can increase exposure Elemental or inorganic mercury can be transformed by bacteria into organic mercury (methyl mercury-most toxic) - Absorbed bio accumulated and passed through the food chain - Organisms at the top of the food chain therefore absorbs methyl mercury Mercury appears to be toxic to most organism, but selenium is believed to reduce the toxic effects - Many marine animals have selenium- tolerate higher levels of HG - The tolerance of large predatory fish can be 10,000 time higher than normal background levels

Primary Pollutant

air pollutant emitted directly from a source