Polycyclic aromatic hydrocarbons: Environmental effects
Description
Polycyclic aromatic hydrocarbons have moderate to high acute (short-term) toxicity to aquatic life and birds. Some cause damage and death to agricultural and ornamental crops. They have moderate to high chronic (long-term) toxicity to aquatic life. Insufficient data are available on the acute or chronic toxicity to land animals. Polycyclic aromatic hydrocarbons are moderately persistent in the environment, and can bioaccumulate. The concentrations of polycyclic aromatic hydrocarbons found in fish and shellfish is expected to be much higher than the environment from which it was taken.
Entering the environment
Polycyclic aromatic hydrocarbons travel through the atmosphere as a gas or attached to dust particles. They are carried by air currents and deposited by dry or wet (rain, dew, etc) deposition. When deposited in water they sink to the bottom of lakes and rivers. Some will move though the soil to contaminate ground water.
Where it ends up
Polycyclic aromatic hydrocarbons usually enter the air when released to the environment. Some evaporate into the air when released to soil or water.
They then often attach to dust particles. Polycyclic aromatic hydrocarbons can break down by reacting with sunlight and other chemicals in the air, over a period of days to weeks. Polycyclic aromatic hydrocarbons do not dissolve easily in water. They stick to dust or dirt particles and settle to the bottom of lakes and rivers. Microorganisms will break them down in soil or water over a period of weeks to months. Mixed microbial populations in sediment/water systems may degrade some polycyclic aromatic hydrocarbons, with degradation progressively decreasing with increasing molecular weight.
Environmental guidelines
Australian Water Quality Guidelines for Fresh and Marine Waters (ANZECC, 1992):
Maximum of 3.0 micrograms per Litre (i.e. 0.000003 g/L) in fresh or marine waters.
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