By Lynda Huckestein, Project Chemist, Kelso, WA
Aquatic Humic Substances (AHS) result from the decomposition of plant and animal residues and are found in soil, sediment, and water. They are widespread in nature and are mostly comprised from naturally occurring dissolved organic matter in water.
By Jeff Christian, Kelso, WA, updated July 2, 2010
General Discussion:
The analysis of various sample matrices (seawater, sediment, tissue) to determine concentrations of Corexit dispersants used in the Gulf spill requires the use of one or more of the components in the dispersant as a tracer. The primary active ingredient (i.e. the primary surfactant) in the Corexit products is Dioctyl Sulfosuccinate Sodium Salt (DOSS). The other primary ingredients function as carriers until the dispersant is applied. At that point, the lighter fractions evaporate and the water soluble component(s) dissolve in the seawater and rapidly dissipate.
In April 2010, the EPA announced that there is sufficient data to support the removal of saccharin and its salts from the agency’s lists of hazardous wastes, hazardous constituents, and hazardous substances through the Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). These substances no longer meet the criteria for hazardous waste regulation.
Saccharin is a white crystalline powder that is about 300 times sweeter than sucrose. It is typically available in the acid form (saccharin) or as salts (sodium saccharin or calcium saccharin). The most common uses are in diet soft drinks, table-top sweeteners, syrups, juices, chewing gums, and jellies. It is also used in personal-care products (e.g. toothpaste, mouthwash, dental cleaners, lipstick), pharmaceuticals (e.g. coatings on pills), and electroplating (e.g. brightener in nickel-plating baths).
On April 29, 2010, the EPA announced two proposed air toxics standards: (1) an amendment to emission guidelines and new source performance standards, and (2) proposed new rules to clearly define and identify solid and non-solid, non-hazardous secondary materials.
The two air toxic standards will affect emissions from industrial, commercial, and institutional boilers and process heaters. One is written for major source facilities, which are those that emit or have the potential to emit 10 or more tons per year of any single air toxin or over 25 tons per year of any combination of air toxins. The second is for area source facilities that emit less than 10 tons per years of a single air toxin or less than 25 tons of any combination.
By Pradeep Divvela, Project Chemist, Kelso, WA
Sequential extraction is an analytical process that chemically leaches metals out of soil, sediment and sludge samples. The purpose of sequential “selective” extraction is to mimic the release of the selective metals into solution under various environmental conditions.
One commonly used sequential extraction procedure is designed to partition different trace metals based on their chemical nature.
The sequential extraction process is typically accomplished in four (4) steps using:
