Soil persistence

Environmental. The A/-methylcarbamates generally are biodegradable and of low soil persistence with half-Hves for carbaryl and aldicarb of 1—2 weeks and of carbofuran of 1—4 months. Certain carbamates are highly toxic to birds with oral LD qS for mallard, eg, pheasant, in mg/kg carbofuran, 0.40, 4.2 mexacarbate, 3.0, 4.5 and methomyl, 16, 15 compared to carbaryl >2000. Fish toxicity of carbamates is generally low, but these compounds are extremely toxic to bees. In cases of human poisoning, atropine is a specific antidote. 

Many factors affect the mechanisms and kinetics of sorption and transport processes. For instance, differences in the chemical stmcture and properties, ie, ionizahility, solubiUty in water, vapor pressure, and polarity, between pesticides affect their behavior in the environment through effects on sorption and transport processes. Differences in soil properties, ie, pH and percentage of organic carbon and clay contents, and soil conditions, ie, moisture content and landscape position climatic conditions, ie, temperature, precipitation, and radiation and cultural practices, ie, crop and tillage, can all modify the behavior of the pesticide in soils. Persistence of a pesticide in soil is a consequence of a complex interaction of processes. Because the persistence of a pesticide can govern its availabiUty and efficacy for pest control, as weU as its potential for adverse environmental impacts, knowledge of the basic processes is necessary if the benefits of the pesticide ate to be maximized. 

The objectives of the soil persistence experiments were (1) to learn the effect of soil type and concentration on the TCDD degradation rate, (2) to isolate and characterize degradation products from DCDD and TCDD, and (3) to determine whether chlorodioxins could be formed from chlorophenol condensation in the soil environment. This last study was essential since quality control at the manufacturing level could reduce or eliminate the formed dioxin impurity. But the biosynthesis of chlorodioxins by chlorophenol condensation in the soil environment could not be controlled and would have connotations for all chlorophenol-de-rived pesticides if formation did occur. The same question needed to be answered for photochemical condensation reactions leading to chloro-... 

The soil persistence data suggested that TCDD is a relatively persistent compound. This is relative to various pesticides in the same con-... 

The N -Ditroso derivatives of the dinitroaniline herbicides bu-tralinSa and pendimethalin were quite stable in aerobic soils, persisting over several months. An aerobic actinotnycete of the Streptonyces genus was isolated from soil that metabolized N -ni-trosopendimethalin in laboratory culture.e... 

Anticipated soil persistence mobility of parent and degfedates Water solubility oil sorption (Kp, K,... 

The polar character of neonicotinoids makes them, in general, potentially mobile in soil. Acetamiprid and nitenpyram have short soil persistence. Imidacloprid and thi-amethoxam, however, are sufficiently persistent in soil to be used for soil treatment. The definition of soil residues for the various neonicotinoid compounds except for imidacloprid are the parent compound and it metabolites. The metabolites of acetamiprid are lM-1-2, lM-1-4 and lC-0 (Figure 6). The metabolites of nitenpyram are 2-[N-(6-chloro-3-pyridyl-methyl)-A-ethyl]amino-2-methyliminoacetic acid (CPMA) and A-(6-chloro-3-pyridylmethyl)-Ai-ethyl-A -methylformamidine] (CPMF). 

Short, because compounds are disseminated as an aerosol. Soil persistent. Surface (wood, metal, masonry, mbber, paint) persistent. Water persistent when material is covered with water, an insoluble film forms, which prevents further hydrolysis. 

Ofloxacin rr 0 I I I COOH Human medicine - High levels in hospital WW [4,5] It s strongly sorbed onto soil. Persistent in the environment [1]... 

Isensee, A.R., Holden, E.R., Woolson, E.A., and Jones, G.E. Soil persistence and aqnatic bioaccnmnlation potential of... 

Boyd SA, Kao CW, Suflita JM. 1984. Fate of 3,3 -dichlorobenzidine in soil persistence and binding. Environ Tox Chem 3 201-208. 

Degradation of parathion in soil was by hydrolysis to p-nitro-phenol and diethylthiophosphoric acid and reduction to aminopara-thion (25,26). Chemical oxidation of parathion in soils and waters was not prevalent, although oxidation of the phosphorus-sulfur bond has been shown to occur under ultraviolet light and in oxidizing environments (26). At ordinary levels of application to soil, parathion was degraded within weeks if microbial activity was available (27). Accumulations even after repeated applications were unlikely (28). When higher concentrations were applied to soil, persistence increased. Simulated spills of concentrated parathion resulted in a 15% residue after five years (29) and 0.1% after 16 years (30). 

To determine the soil persistence of the two phenoxy herbicides contained In Herbicide Orange and the dioxin contaminant. 

Field Studies on the Soil-Persistence and Movement of 2,4-D 2,4,5-T, and TCDD." Appendix G. Disposition of Orange Herbicide by Incineration. Final Environmental Statement, November 1974. Department of the Air Force, Washington, D.C. 

Jacobs LW, Chou SF, Tiedje JM. 1976. Fate of polybrominated biphenyls (PBBs) in soils Persistence and plant uptake. J Agric Food Chem 24 1198-1201. 

Soil persistence of triazines is important in forest usages. Much literature confirms that significant gains are made by reducing herbaceous plant cover for more than 1 year following planting. The triazines (e.g., simazine, atrazine,... 

Soil t,/2 = 72-7584 h, based on soil persistence and soil biodegradation studies (Bollag et al. 1978 Medvedev Davidov 1981 selected, Howard et al. 1991). 

Soil persists for 6-10 wk in soil (Hartley Kidd 1987 Tomlin 1994) t,/2 = 4 to 8 d depending upon soil type (Herbicide Handbook 1989) persists in soil 42-70 d (Worthing Hance 1991) ... 

Soil persistence of 18 months (Edwards 1973 quoted, Morrill et al. 1982) persistence of 12 months in soil (Wauchope 1978) ... 

Smith, A.E. (1979) Soil persistence experiments with (14C) 2,4-D in herbicidal mixtures and field persistence studies with triallate and trifluralin both singly and combined. Weed Res. 19, 165-170. 

Soil persistence of less than one month (Wauchope 1978) ... 

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