PAHs are a group of over 100 different compounds formed during the incomplete burning of coal, oil & gas and other organic substances. More Details
Our Technical team came across this reference, during their Literature review discussions more
It covers Approaches to Understanding Environmental Weathering. It is entitled ‘Comprehensive Study of a Heavy Fuel Oil Spill: Modeling and Analytical Approaches to Understanding Environmental Weathering’ [Lemkau 2004]
“Decades of oil spill research have been based on one-dimensional gas chromatography (GC) – based techniques. GC only allows examining of GC-amenable oil components, primarily the saturates and aromatic fractions of oil. Many studies examining weathering processes have focused exclusively on these fractions (Diez et al., 2005; Douglas et al., 2002; Ezra et al., 2000). However, technology has improved and comprehensive twodimensional gas chromatography (GC×GC) allows unprecedented detailed examination of these classically studied saturate and aromatic fractions (Farwell et al., 2009; Wardlaw et al., 2008; Arey et al., 2007a).”
Environmental forensic chemistry investigations are critical to the determination of liability under a variety of scenarios, including but not limited to: allocation of responsibilities and costs for property transfers; litigation pertaining to insurance claims; toxic claims; and marine pollution events such as oil spills.
Environmental forensic evaluations may also be a key component for liability management in site remediation activities including legacy site cleanup.
Chemtest uses an interdisciplinary approach to problem solving for environmental forensics investigations. An essential element of our success is effective and defensible environmental sampling and analysis design and planning for complex environmental problems.
The use of environmental forensic tools provides multiple lines of evidence in the allocation of responsible parties at sites that have been contaminated.
‘DDT is likely one of the most famous and controversial pesticides ever made’. More ..
What is DDT?
DDT (dichloro-diphenyl-trichloroethane) was developed as the first of the modern synthetic insecticides in the 1940s. It was initially used with great effect to combat malaria, typhus, and the other insect-borne human diseases among both military and civilian populations. It also was effective for insect control in crop and livestock production, institutions, homes, and gardens. https://www.epa.gov/ingredients-used-pesticide-products/ddt-brief-history-and-status
In the United States, DDT was used extensively on agricultural crops, particularly cotton, from 1945 to 1972. DDT was also used to protect soldiers from insect-borne diseases such as malaria and typhus during World War II, and it remains a valuable public health tool in parts of the tropics.
The heavy use of this highly persistent chemical, however, led to widespread environmental contamination and the accumulation of DDT in humans and wildlife – a phenomenon brought to public attention by Rachel Carson in her 1962 book, Silent Spring. https://www.epa.gov/international-cooperation/persistent-organic-pollutants-global-issue-global-response#pops
The 2012 Article in the New York Times by Liza Grizwold entitled ‘How ‘Silent Spring’ Ignited the Environmental Movement’ notes:
‘Though she did not set out to do so, Carson influenced the environmental movement as no one had since the 19th century’s most celebrated hermit, Henry David Thoreau, wrote about Walden Pond. “Silent Spring” presents a view of nature compromised by synthetic pesticides, especially DDT. Once these pesticides entered the biosphere, Carson argued, they not only killed bugs but also made their way up the food chain to threaten bird and fish populations and could eventually sicken children’.
Much of the data and case studies that Carson drew from weren’t new; the scientific community had known of these findings for some time, but Carson was the first to put them all together for the general public and to draw stark and far-reaching conclusions. In doing so, Carson, the citizen-scientist, spawned a revolution.’
Based on studies in animals, a relationship between DDT exposure and reproductive effects in humans is suspected. In addition, some animals exposed to DDT in studies developed liver tumors. As a result, today, DDT is classified as a probable human carcinogen by U.S. and international authorities.
-Known to be very persistent in the environment
-Will accumulate in fatty tissues, and
-Can travel long distances in the upper atmosphere.
After the use of DDT was discontinued in the United States, its concentration in the environment and animals has decreased, but because of its persistence, residues of concern from historical use still remain.
At Chemtest we carry out testing for a wide range of Pesticides including Organochlorine Pesticides such as DDT.
Other Useful References
The Physiologically Based Extraction Test (PBET) is used to provide site specific estimates of bioavailable arsenic from soil.
CLEA SGV for arsenic is 32 mg/kg. This is based on the assumption that 100% of the arsenic in soil is taken up by the systemic circulation (i.e. bioavailable).
In most cases, only a fraction of the total arsenic is bioavailable. This fraction can be quantified using the Physiologically Based Extraction Test (PBET).
The PBET recreates conditions found in the gastro-intestinal tract of a small child.
It is a 2 phase extraction – simulating conditions in the stomach and small intestine.
Extracts are analysed for arsenic by ICP-MS.
Results for total arsenic are reported along with percentage of the total, which is bioavailable.
The method can also be used for other metals such as lead, chromium, nickel, mercury, cadmium, copper and zinc.
For more information contact Our Technical Manager Keith Jones
This presentation discusses Laboratory Data Variability.
Site Investigation and the assessment of contaminated land is a complex process, involving factors such as:-
Site History, Sampling and Laboratory Data Variability
Apparent Anomalous & inconsistent laboratory results can result in delays & cost implications
An awareness and appreciation of laboratory data variability can assist the site engineer / consultant in evaluating the correlation between the site history and laboratory results as well as identifying any apparent site anomalies. ( presentation )
Assessing Petroleum Degradation using Chromatograms
Laboratories utilise a number of techniques to determine levels of TPH Degradation. As part of the process, the Chemist will review Chromatograms and will consider several factors:-
|Compound depletion||Specific compounds are more resistant to biodegradation and their presence or depletion can be used to assess weathering|
|The n-alkane distribution||The n-alkanes in middle distillates, such as diesel fuel, heating oils or kerosene, normally show an even distribution, evidenced by a bell-shaped. An uneven or jagged distribution is often evidence of degradation|
|Unresolved complex mixture (UCM)||The UCM is the hump at the base of a GC/FID trace and a mixture of complex cyclo- and iso-alkanes that are unresolvable through conventional gas chromatography(McGovern, 1999).|
|Heavy versus light n-alkanes||Under aerobic conditions, lighter n-alkanes are normally
removed quicker compared to the heavier n-alkanes (Mohantya & Mukherji, 2008).
In addition to the above, at Chemtest, we also utilise GCxGC traces, which provide us with further lines of evidence.
Please contact Chemtest if you have any questions regarding testing samples to determine levels of degradation.
Find out more information on Environmental Forensics Here
Ref : Gil Oudijk (2012). Age Dating of Middle-Distillate Fuels Released to the Subsurface Environment, Earth Sciences, Dr. Imran Ahmad Dar (Ed.), ISBN: 978-953-307-861-8, InTech, Available from:http://www.intechopen.com/books/earth-sciences/age-dating-of-middle-distillate-fuels-released-to-thesubsurface-environment
Atrazine is part of the Triazine chemical class, which includes Simazine and Propazine due to their common mechanism of toxicity. http://bit.ly/29031tM The scientific name for Atrazine is 6-chloro-N-ethyl-N’-(1-methylethyl)-triazine-2,4-diamine. After atrazine has been applied to soils, it will remain there for several days to several months. http://bit.ly/1Jevade
What can Chemgenie do for you?
Chemgenie – An Innovative Mobile Site App for the Environmental Industry
Chemgenie is a free mobile App, available for both Apple and Android devices, which has been developed to provide clients with a quick and simple capability to manage their consumables, collections and testing, regardless of where they are. Anytime & Anywhere …
Chemgenie App allows the site engineer to
Tasks that previously required site workers to manually complete detailed paperwork, or to liaise with their office or the laboratory for assistance, can now be seamlessly fulfilled on site. Chemgenie allows clients to spend less time organising samples and containers, allowing them more time more time on everything else!
Chemgenie is now available for free in the App Store.
Download Chemgenie today.
Chemtest’s Free Autumn Training Event 20th October
Section 1: Guest Speakers (Waste, Topsoil, Environmental Case Study )- TBC
Section 2: The Laboratory Process, Deviating Samples, Understanding Laboratory Data Variability, Quality
Section 3: Asbestos, Microbiology, Scheduling correct & fit for purpose Tests
Section 4: Interactive Seminar on Advances & Innovations in Environmental Testing
Reserve your place today
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