Traditional sources of contaminants

• Organic chemical contaminants-pollutants


  A great variety of contaminants with different chemical structures, properties and effects
• Compartments where contaminants are found

  • Air
  • Water
  • Soil
• Contaminants


  • Move around and distribute in the environment
• Types of effects of contaminants

  • Carcinogenic
  • Endocrine disruptors
• Physico-chemical properties of contaminants

  Hydrophobic, polar, volatile, persistent - do not degrade in the environment
• Sources of contaminants


  • Leaking tanks
  • Incineration
  • Industry
  • Sewage
  • Runoff
• One contaminant can be emitted by multiple sources


  One source emits many different contaminants
• Main categories of contaminant sources

  • Point sources (well defined in time and space, accidental spills, leaking, underground tank)
  • Diffuse sources (atmospheric deposition, urban runoff)
• Underground storage tanks


  Many activities involve storing chemicals underground, leakage is difficult to detect, can be a major source of groundwater pollution
• BTEX


  Hydrocarbons, toxic volatile organic compounds found in gasoline, largest group related to human health effects like headaches, irritations, reduced coordination, cancer, brain damage
• Chlorinated solvents


  Very large family of compounds containing chlorine, very volatile, used in many domestic, commercial and industrial activities, can cause nervous system depression
• Groundwater contamination is often caused by BTEX and chlorinated solvents
• Types of air pollution

  • Smog (winter and summer)
  • Particulate matter
• Winter smog


  Small particles, often considered the deadliest form of air pollution, Group 1 carcinogen (WHO), can penetrate deep into lungs and bloodstream, made of SO2, NOx, CO, mineral dust, organic matter and soot
• Summer smog (photochemical)


  Formed by a chain reaction involving UV light, hydrocarbons and nitrogen oxides, leads to the formation of peroxyacetylnitrate (PAN) which is a powerful eye/respiratory irritant and damages materials and plants
• Temperature inversion


  Normal situation is that air temperature decreases with altitude, but in some atmospheric-topographic conditions warm air can be trapped above cool air, leading to a buildup of pollutants and more chemical reactions
• Polycyclic aromatic hydrocarbons (PAHs)


  Large family of compounds made of benzene rings, the most widespread organic pollutants, occur naturally and are produced by incomplete combustion, some are carcinogenic, mutagenic and teratogenic
• Polar bears are affected by persistent organic pollutants (POPs) that can move long distances and accumulate in the food chain
• Persistent organic pollutants (POPs)


  Persistent, resist chemical, biological and photolytic degradation, capable of long-range transport, bioaccumulate in the food chain
• Stockholm Convention


  International treaty signed in 2001 to ban or restrict the production and use of 12 POPs (the "dirty dozen")
• DDT


  Organochlorine pesticide first synthesized in 1874, used extensively during and after WWII, banned in most countries in the 70s-80s but still used for disease vector control
• Dioxins and furans


  Unintentional byproducts formed whenever chlorine and organic matter are brought together at high temperatures, sources include residential combustion, open waste burning, wood preservation, iron and steel industry
• Emissions of dioxins and furans in Switzerland have decreased due to controls and destruction during incineration
• PCBs


  Polychlorinated biphenyls, very stable industrial chemicals with many uses, phased out in the 1970s but still persist in the environment, can cause carcinogenic, dermal, hepatic and other effects