Environmental chemistry

White bags filled with contaminated stones line the shore near an industrial oil spill in Raahe, Finland
White bags filled with contaminated stones line the shore near an industrial oil spill in Raahe, Finland

Environmental chemistry is the scientific study of the chemical and biochemical phenomena that occur in natural places. It should not be confused with green chemistry, which seeks to reduce potential pollution at its source. It can be defined as the study of the sources, reactions, transport, effects, and fates of chemical species in the air, soil, and water environments; and the effect of human activity and biological activity on these. Environmental chemistry is an interdisciplinary science that includes atmospheric, aquatic and soil chemistry, as well as heavily relying on analytical chemistry and being related to environmental and other areas of science.

Environmental chemistry is the study of chemical processes occurring in the environment which are impacted by humankind's activities. These impacts may be felt on a local scale, through the presence of urban cities' air pollutants or toxic substances arising from a chemical waste site, or on a global scale, through depletion of stratospheric ozone or global warming. The focus in our courses and research activities is upon developing a fundamental understanding of the nature of these chemical processes, so that humankind's activities can be accurately evaluated.

Environmental chemistry involves first understanding how the uncontaminated environment works, which chemicals in what concentrations are present naturally, and with what effects. Without this it would be impossible to accurately study the effects humans have on the environment through the release of chemicals.

Environmental chemists draw on a range of concepts from chemistry and various environmental sciences to assist in their study of what is happening to a chemical species in the environment. Important general concepts from chemistry include understanding chemical reactions and equations, solutions, units, sampling, and analytical techniques.[1]

Contamination

A contaminant is a substance present in nature at a level higher than fixed levels or that would not otherwise be there.[2][3] This may be due to human activity and bioactivity. The term contaminant is often used interchangeably with pollutant, which is a substance that has a detrimental impact on the surrounding environment.[4][5] Whilst a contaminant is sometimes defined as a substance present in the environment as a result of human activity, but without harmful effects, it is sometimes the case that toxic or harmful effects from contamination only become apparent at a later date.[6]

The "medium" (e.g. soil) or organism (e.g. fish) affected by the pollutant or contaminant is called a receptor, whilst a sink is a chemical medium or species that retains and interacts with the pollutant e.g. as carbon sink and its effects by microbes.

Environmental indicators

Chemical measures of water quality include dissolved oxygen (DO), chemical oxygen demand (COD), biochemical oxygen demand (BOD), total dissolved solids (TDS), pH, nutrients (nitrates and phosphorus), heavy metals, soil chemicals (including copper, zinc, cadmium, lead and mercury), and pesticides.

Applications

Environmental chemistry is used by the Environment Agency (in England and Wales), the United States Environmental Protection Agency, the Association of Public Analysts, and other environmental agencies and research bodies around the world to detect and identify the nature and source of pollutants. These can include:

Methods

Quantitative chemical analysis is a key part of environmental chemistry, since it provides the data that frame most environmental studies.[10]

Common analytical techniques used for quantitative determinations in environmental chemistry include classical wet chemistry, such as gravimetric, titrimetric and electrochemical methods. More sophisticated approaches are used in the determination of trace metals and organic compounds. Metals are commonly measured by atomic spectroscopy and mass spectrometry: Atomic Absorption Spectrophotometry (AAS) and Inductively Coupled Plasma Atomic Emission (ICP-AES) or Inductively Coupled Plasma Mass Spectrometric (ICP-MS) techniques. Organic compounds are commonly measured also using mass spectrometric methods, such as Gas chromatography-mass spectrometry (GC/MS) and Liquid chromatography-mass spectrometry (LC/MS). Tandem Mass spectrometry MS/MS and High Resolution/Accurate Mass spectrometry HR/AM offer sub part per trillion detection. Non-MS methods using GCs and LCs having universal or specific detectors are still staples in the arsenal of available analytical tools.

Other parameters often measured in environmental chemistry are radiochemicals. These are pollutants which emit radioactive materials, such as alpha and beta particles, posing danger to human health and the environment. Particle counters and Scintillation counters are most commonly used for these measurements. Bioassays and immunoassays are utilized for toxicity evaluations of chemical effects on various organisms. Polymerase Chain Reaction PCR is able to identify species of bacteria and other organisms through specific DNA and RNA gene isolation and amplification and is showing promise as a valuable technique for identifying environmental microbial contamination.

Published analytical methods

Peer-reviewed test methods have been published by government agencies[11][12] and private research organizations.[13] Approved published methods must be used when testing to demonstrate compliance with regulatory requirements.

See also

References

  1. ↑ Williams, Ian. Environmental Chemistry, A Modular Approach. Wiley. 2001. ISBN 0-471-48942-5
  2. ↑ Glossary to the Buzzards Bay Watershed Management Plan
  3. ↑ American Meteorological Society. Glossary of Meteorology
  4. ↑ North Carolina State University. Department of Soil Science. "Glossary."
  5. ↑ Global Resource Action Center for the Environment (GRACE). New York, NY. Sustainable Table: Dictionary
  6. ↑ Harrison, R.M (edited by). Understanding Our Environment, An Introduction to Environmental Chemistry and Pollution, Third Edition. Royal Society of Chemistry. 1999. ISBN 0-85404-584-8
  7. ↑ United States Environmental Protection Agency (EPA). Washington, DC. "Protecting Water Quality from Agricultural Runoff." Document No. EPA 841-F-05-001. March 2005.
  8. ↑ EPA. "Protecting Water Quality from Urban Runoff." Document No. EPA 841-F-03-003. February 2003.
  9. ↑ Sigel, A. (2010). Sigel, H.; Sigel, R.K.O., eds. Organometallics in Environment and Toxicology. Metal Ions in Life Sciences. 7. Cambridge: RSC publishing. ISBN 978-1-84755-177-1.
  10. ↑ vanLoon, Gary W.; Duffy, Stephen J. (2000). Environmental Chemistry. Oxford: Oxford. p. 7. ISBN 0-19-856440-6.
  11. ↑ EPA Clean Water Act methods: "Guidelines Establishing Test Procedures for the Analysis of Pollutants." Code of Federal Regulations, 40 CFR Part 136.
  12. ↑ EPA methods under the Resource Conservation and Recovery Act (RCRA): "Test Methods for Evaluating Solid Waste, Physical/Chemical Methods." Document No. SW-846. February 2007.
  13. ↑ Clescerl, Leonore S.(Editor), Greenberg, Arnold E.(Editor), Eaton, Andrew D. (Editor). Standard Methods for the Examination of Water and Wastewater (20th ed.) American Public Health Association, Washington, DC. ISBN 0-87553-235-7. This publication is also available on CD-ROM and online Archived February 11, 2016, at the Wayback Machine. by subscription.

Further reading

  • Stanley E Manahan. Environmental Chemistry. CRC Press. 2004. ISBN 1-56670-633-5.
  • Julian E Andrews, Peter Brimblecombe, Tim Jickells, Peter Liss, Brian Reid. An Introduction to Environmental Chemistry. Blackwell Publishing. 2004. ISBN 0-632-05905-2.
  • Rene P Schwarzenbach, Philip M Gschwend, Dieter M Imboden. Environmental Organic Chemistry, Second edition. Wiley-Interscience, Hoboken, New Jersey, 2003. ISBN 0-471-35750-2.
  • NCERT XI textbook.[ unit 14]
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