Environmental Engineering Reference
In-Depth Information
that the USEPA has recognized that very stable metal-cyanide complexes,
such as the iron-cyanide complex, are nontoxic (unless exposed to signifi-
cant UV radiation); therefore, these fractions are not considered when defin-
ing cyanide toxicity. Ingestion of free cyanide at concentrations in excess of
the MCL causes both acute effects (e.g., rapid breathing, tremors, and neuro-
logical symptoms) and chronic effects (e.g., weight loss, thyroid effects, and
nerve damage). Under the current primary drinking water standards, pub-
lic water systems are required to monitor their systems to minimize pubic
exposure to cyanide levels in excess of the MCL.
Hydrogen cyanide gas is also toxic, and the Occupational Safety and
Health Administration (OSHA) has set a permissible exposure limit (PEL)
of 10 ppmv for HCN inhalation. HCN also has a strong, bitter, almond-like
smell and an odor threshold of approximately 1 ppmv. Considering the fact
that HCN is relatively nonvolatile (see above), a slight cyanide odor ema-
nating from a water sample suggests very high aqueous cyanide concen-
trations—greater than 10 to 50 mg/L, which is in the range of a lethal or
near-lethal dose with the ingestion of one pint of water.
Portable Field Monitors to Measure Volatile Organic Compounds
Volatile organic compounds (VOCs) are a group of highly utilized chemicals
that have widespread applications, including use as fuel components, solvents,
and cleaning and liquefying agents in degreasers, polishes, and dry-cleaning
solutions. VOCs are also used in herbicides and insecticide for agriculture
applications. Laboratory-based methods for analyzing VOCs are well estab-
lished; however, analyzing VOCs in the lab is time consuming, and obtaining
a result may require several hours to several weeks, depending on the specific
method. Faster commercially available methods for analyzing VOCs quickly
in the field include the use of a portable gas chromatograph (GCs), mass spec-
trometer (MS), or gas chromatograph/mass spectrometer (GC/MS), all of
which can be used to obtain VOC concentration results within minutes. These
instruments can be useful in rapid confirmation of the presence of VOCs in
an asset or for monitoring an asset on a regular basis. In addition, portable
VOC analyzers can analyze for a wide range of VOCs, such as toxic industrial
chemicals (TICs), chemical warfare agents (CWAs), drugs, explosives, and aro-
matic compounds. Several easy-to-use, portable VOC analyzers currently on
the market are effective in evaluating VOC concentrations in the field. These
instruments utilize gas chromatography, mass spectroscopy, or a combination
of both methods, to provide near-laboratory-quality analysis for VOCs.
Radiation Detection Equipment
Radioactive substances (radionuclides) are known health hazards that emit
energetic waves or particles that can cause both carcinogenic and noncarci-
nogenic health effects. Radionuclides pose unique threats to source water
