Mirex in water

Burns SE, JP Hassett, MV Rossi (1996) Binding effects on humic-mediated photoreaction intrahumic dechlorination of mirex in water. Environ Sci Technol 30 2934-2941. 

Because they are not likely to move through the soil, very little will get into underground water. Mirex and chlordecone can stay in soil, water, and sediment for years. Both compounds are slowly broken down in soil, water, and sediment. Mirex is broken down more quickly than chlordecone. Mirex is broken down to photomirex, which can also cause harmful health effects. Photomirex is even more poisonous than mirex. It is produced when sunlight reacts with mirex in water or in the air. Fish or animals that live in waters that contain mirex or chlordecone, or that eat other animals contaminated with mirex or chlordecone, can build up these substances in their bodies. The amounts of mirex and chlordecone in their bodies may be several times greater than the amount in their prey or in the surrounding water. See Chapter 3 for more information on the chemical and physical properties of mirex and chlordecone. See Chapter 5 for more information on their occurrence and what happens to them in the environment. 

The degradation of mirex in water occurs primarily by photolysis. During the photodecomposition of mirex, the chlorine atoms are replaced by hydrogen atoms. The primary photoreduction product of... 

BW daily, equivalent to 0.014 mg daily for a 70-kg person. In 1995, the recommended concentration of mirex in water should not exceed 0.001 p-g/L in order to protect human health, freshwater and marine life, irrigated crops, and watered livestock. Fish in the human diet should not contain more than 0.1 mg mirex/kg fresh weight. Average acceptable ambient air concentrations recommended for the protection of human health range between 0.03p,g/m in New York to 0.88 xg/m in Pennsylvania in Kentucky, air emission levels of mirex products should not exceed 232.0 p-g per hour. 

Wilson and co-workers [332, 333] have discussed the determination of aldrin, chlordane, dieldrin, endrin, lindane, o,p and p,p isomers of DDT and its metabolites, mirex, and toxaphene in seawater and molluscs. The US environmental Protection Agency has also published methods for organochlo-rine pesticides in water and wastewater. The Food and Drug Administration (USA) [334] has conducted a collaborative study of a method for multiple organochlorine insecticides in fish. Earlier work by Wilson et al. [333, 335] in 1968 indicated that organochlorine pesticides were not stable in seawater. 

Mirex residues in water, sediments, and fauna in a South Carolina coastal marsh 18 months after application of 4.2 g/ha... 

Mirex is a very persistent compound in the environment and is highly resistant to both chemical and biological degradation. The primary process for the degradation of mirex is photolysis in water or on soil surfaces photomirex is the major transformation product of photolysis. In soil or sediments, anaerobic biodegradation is also a major removal mechanism whereby mirex is slowly dechlorinated to the 10-monohydro derivative. Aerobic biodegradation on soil is a very slow and minor degradation process. Twelve years after the application of mirex to soil, 50% of the mirex and mirex-related compounds remained on the soil. Between 65--73% of the residues recovered were mirex and 3-6% were chlordecone, a transformation product (Carlson et al. 1976). 

Although release of mirex to the atmosphere was probably small in comparison to amounts released to surface water, soil, and sediment, infrequent detections of minute concentrations of mirex in air (mean concentration 0.35 pg/m ) and rainfall (<0.5 ng/L [ppt]) samples have been reported many years after production ceased (Hoff et al. 1992 Strachan 1990 Wania and MacKay 1993). Arimoto (1989) estimated that 5% of the total input of mirex to Lake Ontario was attributed to atmospheric deposition. 

When released to surface waters, mirex will bind primarily (80-90%) to the dissolved organic matter in the water with a small amount (10-20%) remaining in the dissolved fraction, because mirex is a highly hydrophobic compound (Yin and Hassett 1989). Mean mirex concentrations in sediments, collected at four basins in Lake Ontario between 1982 and 1986, ranged from 30 to 38 pg/kg in three of the basins within the water circulation pattern of the lake. A fourth basin outside the pattern showed much lower concentrations (6.4 pg/kg), indicating that mirex was being transported with the lake water (Oliver et al. 1989). The residence time for mirex in Lake Ontario water was estimated to be 0.3 years. This indicated that mirex was either scavenged by particles or was chemically reactive and, therefore, was rapidly removed from the water column (Arimoto 1989). 

Mirex was detected in water samples taken in 1972 from areas in Mississippi that had been aerially treated with mirex to control the imported red fire ant (Spence and Markin 1974). Water samples taken from the bottom of a pond showed residue values that remained higher and more constant than those taken from the surface of the pond. Water showed the highest residues immediately after treatment (bottom, 0.53 pg/L [ppb] surface, 0.02 pg/L [ppb]), and detectable levels were still present as long as 3 months after treatment (bottom, 0.005 pg/L [ppb] surface, 0.003 pg/L [ppb]) (Spence and Markin 1974). 

The solubility of chlordecone in water is low (1--3 mg/L) and as with mirex, contamination is more likely to be associated with the particulate matter in the water rather than the water itself. Chlordecone was detected primarily in water samples collected in and around the production facility site in Hopewell, Virginia, and in adjacent waters of the James River estuary. Effluent from the Life Sciences Products Company facility contained 0.1 —1.0 mg/L (ppm) chlordecone, while water in holding ponds at the site contained 2--3 mg/L (ppm) chlordecone (Epstein 1978). Levels of chlordecone in river water in August 1975 ranged from not detectable (<50 ng/L [ppt]) in the York River and Swift Creek areas, to levels of 1--4 pg/L (ppb) in Bailey Creek which received direct effluent discharges from the Hopewell Sewage Treatment Plant. Water concentrations of up to 0.3 p g/L (ppb) were detected in the James River at the mouth of Bailey Creek and in the Appomattox... 

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