Abstract Adsorption–desorption processes of Pb at contaminated levels in two variable charge soils were investigated. The red soil (RAR) developed on the Arenaceous rock (clayey, mixed siliceous thermic typic Dystrochrept) adsorbed more Pb2+ than the red soil (REQ) derived from the Quaternary red earths (clayey, kaolinitic thermic plinthite Aquult). One of the most challenging issues of the last decades is the presence of recalcitrant compounds in the effluents of wastewater treatment plants, due to their toxicity on both human health and environment. Although conventional biological processes are usually efficient for the degradation of pollutants occurring in wastewaters, most of these compounds are not effectively removed. Overview of Solid-Phase Extraction. Theory of Sorption and Isolation. Methods Development. Reversed-Phase Solid-Phase Extraction. Normal-Phase Solid-Phase Extraction. Ion-Exchange Solid-Phase Extraction. Environmental Analysis. Drugs and Pharmaceuticals. Food and Natural Products. Automation of Solid-Phase Extraction. Solid Phase Extraction Disks. New Technology in Solid-Phase Extraction.
The ill effects of human exposure to arsenic (As) have recently been reevaluated by government agencies around the world. This has lead to a lowering of As guidelines in drinking water, with Canada decreasing the maximum allowable level from 50 to 25 μg/L and the U.S. From 50 to 10 μg/L. Canada is currently contemplating a further decrease to 5 μg/L. Magnetite is an iron-oxide mineral that occurs naturally on Earth. Because it is also an important component of many anthropogenic materials (e.g., coal fly ash) and synthetic products (e.g., black toner powders), magnetite can be released to the environment through human activities (1). In PNAS, Maher et al. (2) describe the abundant presence in the human brain of magnetite nanoparticles.
Polychlorinated naphthalene (PCN) are the products obtained upon treatment of naphthalene with chlorine. The generic chemical formula is C10H8−(m+n)Cl(m+n). Commercial PCNs are mixtures of up to 75 components and byproducts.[1] The material is an oil or a waxy solid, depending on the degree of chlorination. PCNs were once used in insulating coatings for electrical wires, as well as other applications, but their use has been largely phased out.[2]
Production[edit]
PCNs started to be produced for high-volume uses around 1910 in both Europe and the United States.[2][3] In Europe the largest volume products were called Nibren waxes, made in Germany by Bayer. Other European PCN tradenames included Seekay (UK, from ICI), Clonacire (France), Cerifal (Italy) and Woskol (Poland). In the United States, the largest volume PCN products were called Halowax, from a New York company of the same name that was later owned by Union Carbide and then taken over by Koppers of Pittsburgh, PA, now Beazer East. Although trace amounts of PCNs may be released by natural processes such as wildfires, their industrial uses increased the apparent rates of accumulation in the environment by factors of 10,000 or more.[4]
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Safety[edit]
After about twenty years of commercial production, health hazards began to be reported in workers exposed to PCNs: chloracne,[1] severe skin rashes[5] and liver disease that led to deaths of workers.[6][7] A conference about the hazards was organized at Harvard School of Public Health in 1937, and several more publications dealing with PCN hazards appeared before 1940.[8] PCNs containing three or more chlorines per molecule have typically been found more hazardous than those with fewer,[9] but as the maximum of eight is approached, hazards appear to decrease.[10]
There was a lag of about forty years between disclosure of PCN hazards and government regulation. In the U.S. exposure to PCNs was drastically reduced after 1976, following enactment of the Toxic Substances Control Act. Major equipment manufacturers banned PCNs in their products, and major PCN producers discontinued operations. By 1983 worldwide PCN production had almost halted except for small amounts used in testing and research. Until recent years duPont produced a synthetic rubber, Neoprene FB, made in Northern Ireland using pentachloronaphthalene.[11] Today PCNs are offered commercially by only a few companies, including Ukrgeochem of Simferopol, Ukraine.
Increased cancer risks have been suspected but so far not shown. Current concerns about PCNs include their release as byproducts of waste incineration.[12]
Bioaccumulation[edit]
In 2013, the 9th meeting of the Persistent Organic Pollutants Review Committee, established under the Stockholm Convention on Persistent Organic Pollutants proposed di-,tri-,tetra-,penta-,hexa-, hepta- and octa-chlorinated napthalenes, for listing in Annexes A and C to that Convention.[13]
While some PCNs can be broken down by sunlight and, at slow rates, by certain microorganisms, many PCNs persist in the environment. After more than 80 years of use and total production of several hundred thousand tons, PCN residues are widespread.[10]
See also[edit]
References[edit]
- ^ abvan de Plassche, E.; Schwegler, A. (2002). Polychlorinated naphthalenes, Preliminary Risk Profile.Ministry of VROM/DGM, Netherlands
- ^ abRossberg, Manfred; Lendle, Wilhelm; Pfleiderer, Gerhard; Tögel, Adolf; Dreher, Eberhard-Ludwig; Langer, Ernst; Rassaerts, Heinz; Kleinschmidt, Peter; Strack, Heinz; Cook, Richard; Beck, Uwe; Lipper, Karl-August; Torkelson, Theodore R.; Löser, Eckhard; Beutel, Klaus K.; Mann, Trevor (2006). 'Ullmann's Encyclopedia of Industrial Chemistry - Chlorinated Hydrocarbons'. doi:10.1002/14356007.a06_233.pub2. ISBN3527306730.Cite journal requires
|journal=(help) - ^Chlorinated naphthalenesArchived 2005-07-18 at the Wayback Machine, Chemical Assessment Report S48, 2002, National Industrial Chemicals Notification and Assessment Scheme
- ^Horii, Y.; Falandysz, J.; Hanari, N.; Rostkowski, P. (2004). 'Concentrations and fluxes of chloronaphthalenes in sediment from Lake Kitaura in Japan in past 15 centuries'(PDF). Journal of Environmental Science and Health, Part A. 39 (3): 587. doi:10.1081/ESE-120027727.[permanent dead link]
- ^Teleky, L. (1927). 'Die pernakrankheit'. Klinische Wochenschrift. 6: 845. doi:10.1007/bf01728520.
- ^Flinn, F.B.; Jarvik, N.E. (1936). 'Action of certain chlorinated naphthalenes on the liver'. Proceedings of the Society for Experimental Biology and Medicine. 35: 118. doi:10.3181/00379727-35-8879p.
- ^Chronic exposure increases risk of liver disease. See Chlorinated naphthalenes exposure, Worker Notification Program, National Institute for Occupational Safety and Health
- ^Butler, D.A. (2005). 'The early history of scientific and medical research on 'agent orange''(PDF). Brooklyn Journal of Law and Policy. 13 (2): 531–533. Archived from the original(PDF) on 2006-09-02.
- ^Drinker, C.K.; Warren, M.F.; Bennet, G.A. (1937). 'The problem of possible systemic effects from certain chlorinated hydrocarbons'. Journal of Industrial Hygiene and Toxicology. 19 (7): 283.
- ^ abChlorinated naphthalenes, International Programme on Chemical Safety CICAD, 2001, volume 34
- ^Neoprene FBArchived 2007-09-27 at the Wayback Machine, Material Safety Data Sheet, DuPont de Nemours & Co., 1985
- ^Omura, M.; Masuda, Y.; Hirata, M.; Tanaka, A. (2000). 'Onset of spermatogenesis is accelerated by gestational administration of 1,2,3,4,6,7-hexachlorinated naphthalene in male rat offspring'(PDF). Environmental Health Perspectives. 108 (6): 539–544. doi:10.2307/3454616. JSTOR3454616. PMC1638139. PMID10856028. Archived from the original(PDF) on 2010-06-02.
- ^UNEP (2013). Risk management evaluation on chlorinated naphthalenes, Report of the Persistent Organic Pollutants Review Committee on the work of its ninth meeting, Rome, 14–18 October 2013 (Addendum)
Literature[edit]
- Eva Jakobsson, Lillemor Asplund: Polychlorinated Naphthalenes (PCNs), in The Handbook of Environmental Chemistry, Volume 3K, 2000, p. 97–126, ISBN978-3-540-65838-2, doi:10.1007/3-540-48915-0_5