Herbicides aquatic

Bipyridiniums. The bipyridinium herbicides (Table 2), paraquat and diquat, ate nonselective contact herbicides and crop desiccants. Diquat is also used as a general aquatic herbicide (2,296). Bipyridinium herbicides are organic cations and are retained ia the soil complex via cation exchange. They are strongly sorbed to most soils and are not readily desorbed (332). Both paraquat and diquat are not readily leached (293). 

Other Heterocyclic Nitrogen Derivative Herbicides. The herbicides in this group are heterocycHc nitrogen derivatives that do not readily fall into one of the previously discussed groups. They have a wide range of uses and properties. Most of these herbicides are used for selective, pre-and/or post-emergence weed control. Amitrole is used for post-emergence, nonselective weed control in non-croplands and also as an aquatic herbicide (2,296). 

Aliphatic-Garboxylics. There are only two herbicides present in this class, trichloroacetate [76-03-9] (TCA) and dalapon [75-99-0]. These are used primarily for the selective control of annual and perennial grass weeds in cropland and noncropland (2,299). Dalapon is also used as a selective aquatic herbicide (427). Dalapon and TCA are acidic in nature and are not strongly sorbed by sods. They are reported to be rapidly degraded in both sod and water by microbial processes (2,427). However, the breakdown of TCA occurs very slowly when incubated at 14—15°C in acidic sods (428). Timing not only accelerates this degradation but also increases the numbers of TCA-degrading bacteria. An HA has been issued for dalapon, but not TCA (269). 

Miscellaneous Trifluoromethyl Compounds. The herbicides in this group are used for a wide variety of weed-control purposes. Acifluorfen, lactofen [77501-63-4] and oxyfluorfen are used for selective, pre-, and post-emergence weed control in croplands. Fluorochloridone is used for selective, pre-emergence weed control in cropland, and fluridone, fomesafen, and mefluidide [53780-34-0] are used for post-emergence control (296). Fluridone is also used as an aquatic herbicide (2). 

Miscellaneous Other Herbicides. The herbicides in this group are not readily included in any of the preceding groups. Acrolein [107-02-8] (2-propenal) is used as a contact, aquatic herbicide. Sethoxydim, clethodim, and tridiphane are used for selective, post-emergence weed control. 

The concept of fibrous polymer formulations was extended to the delivery of aquatic herbicides (56). Several herbicides including Diquat, Fluridone, and Endothal were spun into biodegradable poly-caprolactone. Monolithic fibers and a modified monolithic system were produced with levels of herbicide from 5 to 60% by weight. Laboratory and field trials showed efficacious delivery of the active agent. Fibers provided both targeted localized delivery and controlled release of the herbicide to the aquatic weed. 

B. M., Price, M. W., and Stoner, W. C., Jr., Polymeric-pellet delivery systems for controlled release of aquatic herbicides, Toronto Controlled Release Society, Proc. 14th Int. Symp. Control. Rel. Bioact. Materials, 291-292, 1987. 

When added to water as an aquatic herbicide, acrolein undergoes rapid decomposition, especially in sunlight. At the same time, it reacts rapidly with amines, alcohols, and mercaptans of aquatic plants, destroying cell structure and killing the plants (Parent et al. 1992). Mammals drinking acrolein-contaminated water rapidly convert acrolein to saturated alcohol compounds because of the low pH in the upper portion of their GI tracts the primary breakdown product is beta-propionaldehyde (USEPA 1980). 

O Loughlin, E.M. and K.H. Bowmer. 1975. Dilution and decay of aquatic herbicides in flowing channels. Jour. Hydrol. 26 217-235. 

Reinert, K.H. and J.H. Rodgers. 1987. Fate and persistence of aquatic herbicides. Rev. Environ. Contam. Toxicol. 98 61-98. 

Crosby, D.G. and R.K. Tucker. 1966. Toxicity of aquatic herbicides to Daphniamagna. Science 154 289-291. Darr, D.J., S. Yanni, and S.R. Pinnell. 1988. Protection of Chinese hamster ovary cells from paraquat-mediated cytotoxicity by a low molecular weight mimic of superoxide dismutase (DF-Mn). Free Radical Biol. Med. 4 357-363. 

Nelson, N.H. and Faust, S.D. Acidic dissociation constants of selected aquatic herbicides. Environ. Sci. Technol, 3(11) 1186-1188, 1969. 

Paul, E., Johnson, S. and Skinner, K.M. (2006) Fish and invertebrate sensitivity to the aquatic herbicide AquaKleen . J Freshw Ecol, 21, 163—168. 

ALGICIDE. A substance, natural or synthetic, used for destroying or controlling algae. The term is also sometimes used to describe chemicals used for contiolling aquatic vegetation, although these materials ate more properly classified as aquatic herbicides. See Herbicides. 

Aliphatic-Carboxylics. These are used primarily lor the selective control of annual and perennial grass weeds in cropland and noncropland. Dalapon is also used as a seleclive aquatic herbicides. 

The arsenicals came into limited commercial use as soil sterilants. Sodium arsenite was used extensively by the Army Corps of Engineers for control of water hyacinth in Louisiana from 1902 to 1937 (Timmons, 1970), and much more widely as an aquatic herbicide in lakes and ponds. Sodium chlorate was first used for nonselective weed control about 1926. 

Tooby, T.E., J. Lucey, and B. Stott (1980). The tolerance of grass carp, Ctenopharyngodon idella Val., to aquatic herbicides. J. Fish. Biol., 16 591-597. 

Adjuvants (several used as surfactants for aquatic herbicide applications) TT F (Haller and Stocker, 2003)... 

Fluoridone aquatic herbicide and photolysis product iV-methyl formamide Hall electrolytic detector in N mode [469]... 

Reinert, K.H. (1989) Environmental behavior of aquatic herbicides in sediments. In Reactions and Movement of Organic Chemicals in Soils. SSSA Special Publ. No.22, pp. 335-348, Soil Science Society of Ameroca and Society of Argonomy, Madison, Wisconsin. 

Sanders, D.G., Mosier, J.W. (1983) Photolysis of the aquatic herbicide fluridone in aqueous solution. J. Agric. Food Chem. 31, 237-241. 

West, S.D., Day, E.W., Jr., Burger, R.O. (1979) Dissipation of the experimental aquatic herbicide fluridone from lakes and ponds. J. Agric. Food Chem. 27, 1067. 

Uses Paraquat is a colorless, odorless, white or pale yellow crystalline solid that is hygroscopic. Paraquat is a quaternary nitrogen herbicide that is widely used for broadleaf weed control. It is a quick-acting, nonselective compound that destroys green plant tissue on contact and by translocation within the plant. It has been employed for killing marijuana in the United States and Mexico. It also is used as a crop desiccant and defoliant, as well as an aquatic herbicide. Paraquat is highly persistent in the soil environment, with a reported field half-life of greater than 1,000 days.5-7,17... 

Acrolein may be released to water in effluents from its manufacturing plants and use facilities (see Section 4.3 for specific information regarding uses) and from its direct application to water as an aquatic herbicide (IARC 1985 Lue-Hing et al. 1981 WSSA 1983). Data regarding the amount of acrolein released to United States waters were not located. 

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