Soils organophosphorus compounds

Interactions Between Organophosphorus Compounds and Soil Materials I. Adsorption of Ethyl-methylphosphonofluoridate by Clay and Organic Matter Preparations and by Soils," M. H. B. Hayes, P. R. Lundie and M. Stacey, Pestic. Sci., 3 (1972) 619-629. 

A plefhora of methods developed for the determination of triazine compounds in water, soil, crops, biological fluids, etc., have been reported in the literature, and several excellent reviews are available for the interested reader. " More method papers are published on the determination of triazines in water than for all other sample matrices combined (water > soil > crop). The majority of the water method reports relate to the determination of parent triazine compounds plus compounds from one or more other chemical classes of pesticides (e.g., phenoxy acids, carbamates, pheny-lureas, acetanilides, acetamides, organophosphorus compounds, etc.) for generalized multi-residue screening or monitoring purposes. Addressed in other more selective... 

Diazinon (phosphorothioic acid 0,0-diethyl 0-(6-mcthyl-2-(l-mcthylcthyl)-4-pyrimidinyl) ester) is an organophosphorus compound with an anticholinesterase mode of action. It is used extensively to control hies, lice, insect pests of ornamental plants and food crops, as well as nematodes and soil insects in lawns and croplands. Diazinon degrades rapidly in the environment, with half-time persistence usually less than 14 days. But under conditions of low temperature, low moisture, high alkalinity, and lack of suitable microbial degraders, diazinon may remain biologically active in soils for 6 months or longer. 

Dr. P. Jeffers at the State University of New York at Cortland is gathering information to determine the persistence of organophosphorus compounds in groundwater and the effects of various soils on the degradation and transport of these compounds. Both neutral and base hydrolysis processes will be evaluated. Transport studies in soil columns will be conducted to determine the mobility of diazinon in soils. 

Most species of insects are beneficial or even essential to agriculture. Honeybees, for example, are responsible for the pollination of 10 billion worth of produce in the United States. Countless other species take part in nutrient recycling and help maintain soil quality. A small minority of insect species, however, has continually threatened our capacity to grow, harvest, and store crops, and it is against these species that insecticides are used. The most widely used insecticides are chlorinated hydrocarbons, organophosphorus compounds, and carbamates. 

An interesting example deals with the identification of organophosphorus compounds in soil samples [13]. Such compounds can occur as degradation products of chemical weapons (CWs) in soil and other matrices. The convention for the prohibition of chemical weapons sets up procedures for the... 

V. Camel, M. Caude and A. Tambut6, SFE of an organophosphorus compound from soils with capillary GC analysis, J. Chromatogr. Sci., 33, 123-132 (1995). 

Keywords organophosphorus compound nerve agent adsorption decomposition soil metal... 

Soil microorganisms metabolize the organophosphorus compounds fairly rapidly. In general, the drier the soil is, the slower the rate of... 

Ultrasonic extraction Semi-volatiles and non-volatile organics from soils, relatively dry sludges and solid wastes Considered to be less efficient than the other methods detailed rapid method that uses relatively large solvent volumes. Not appropriate for use with organophosphorus compounds as it may cause destruction of the target analytes during extraction... 

Both isofenphos and fonofos were much less persistent in the history versus the nonhistory soils. A major difference between these insecticides and the carbamates was that considerable mineralization of the aromatic ring portion of the organophosphorus compounds occurred. For Isofenphos, considerable quantities (15.2/0 of isofenphos oxon accumulated only in the nonhistory, whereas no such accumulation was noted in the isofenphos-history soil. Several reports of the reduced persistence of isofenphos in field plots following repeated use have appeared (29.30). and isofenphos was withdrawn from the rootworm insecticide market after widespread experiences of control failure following second year applications. This is especially ironic because upon first application to soil isofenphos behaves as one of the most persistent organophosphorus insecticides (31). 

In addition to nematocides acting in the vapour phase, recently compounds have been introduced which are soluble in water and permeate the capillary system of the soil in the form of their aqueous solutions. A small number of these compounds belong to the group of carbamates, while the larger part belongs to the organophosphorus compounds. 

In 1994 Lopez-Avila et al., published their work to expand the use of MAE to 187 volatile and semivolatile organic compounds from soils. The compounds included polyaromatic compounds, phenols, organochlorine pesticides and organophosphorus pesticides. MAE uses microwaves that can easily penetrate into the sample pores causing the solvent trapped in the pores to heat evenly and rapidly. In contrast to conventional heating MAE is a promising technique because ... 

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