Runoff losses

When pure P-endosulfan was allowed to equilibrate in the apparatus, the ratio of the P-isomer to the a-isomer in the gas phase became 8 92 at 20 , suggesting that the P-isomer converts to the a-isomer (Rice et al. 1997). Several investigators have reported rapid initial losses of endosulfan residues from treated plant surfaces due to volatilization (Archer 1973 Terranova and Ware 1963 Ware 1967). One research group (Willis et al. 1987) attributed the limited runoff losses found in soybean fields treated with endosulfan to early losses of the compound during application and to volatilization/degradation of the compound from plant surfaces. Air sampling performed in a wind tunnel under defined conditions (20 air velocity 1 m/sec relative humidity 40-60%) showed that 60% of the initial dose of endosulfan is volatilized from Trench bean surfaces after 24 hours (Rudel 1997). Influences of various pesticide application formulations were not tested. 

Azinphos-methyl will not leach to any great extent in soil (Helling, 1971). Staiff et al. (1975) studied the persistence of azinphos-methyl in a test plot over an 8-yr period. At the end of the eighth year, virtually no azinphos-methyl was detected 30 cm below the surface. In a sugarcane runoff plot, azinphos-methyl was applied at a rate of 0.84 kg/ha 4 times each year in 1980 and 1981. Runoff losses in 1980 and 1981 were 0.08 and 0.55 of the applied amount, respectively (Smith et al., 1983). 

Smith, S., Reagan, T.E., Flynn, J.E., and Willis, G.H. Azinphosmethyl and fenvalerate runoff loss from a sugarcane-insect IPM... 

Eltun, R., Fugleherg, O. and O. Nordheim (1996). The Apelsvoll cropping system experiment Vll. Runoff losses of soil particles, phosphorus, potassium, magnesium, calcium and sulphur. Norwegian Journal of Agricultural Sciences 10 371-384. 

Hall, J.K., R.O. Mumma, and D.W. Watts (1991). Leaching and runoff losses of herbicides in a tilled and unfilled field. Agr. Ecosyst. Environ., 37 303-314. 

Bacci, E., A. Renzoni, C. Gaggi, D. Calamari, A. Franchi, M. Vighi, and A. Seven (1989). Models, field studies, laboratory experiments An integrated approach to evaluate the environmental fate of atrazine (s-triazine herbicide). Agric. Ecosys. Environ., 27 513-522. Baker, J.L. and J.M. Laflen (1979). Runoff losses of surface-applied herbicides as affected by wheel tracks and incorporation../. Environ. Qual., 8 602-607. 

Foy, C.L., J.S. Wilson, S. Mostaghimi, and R.W. Young (1989). Runoff losses of two triazine herbicides and metolachlor from conventional and no-till plots as influenced by sludge. Pestic. Terrest. Aquatic Environ. Proc., May 11-12, pp. 383-396. 

Gaynor, J.D. and V.V. Volk (1981). Runoff losses of atrazine and terbutryn from unlimed and limed soil. Environ. Sci. Technol., 15 440 143. 

Malone, R.W., R.C. Warner, and M.E. Byers (1996). Runoff losses of surface-applied metribuzin as influenced by yard waste compost amendments, no-tillage, and conventional-tillage. Bull. Environ. Contam. Toxicol., 57 536-543. 

Sauer, T.J. and T.C. Daniel (1987). Effect of tillage system on runoff losses of surface-applied pesticides. Soil Sci. Soc. Am. J., 51 410 115. 

Southwick, L.M., G.H. Willis, R.L. Bengston, and T.J. Lormand (1990a). Effect of subsurface drainage on runoff losses of atrazine and metolachlor in southern Louisiana. Bull. Environ. Contam. Toxicol., 45 113-119. 

Webster, E.P. and D.R. Shaw (1996b). Off-site runoff losses of metolachlor and metribuzin applied to differing soybean (Glycine max) production systems. Weed Technol., 10 556-564. 

A vegetative filter strip reduced losses of metribuzin and metolachlor by more than 85% (Webster and Shaw, 1996). Grassed waterways reduced loads of 2,4-D by 69% and 71% under wet and dry conditions, respectively (Asmussen et al., 1977), while trifluralin retention dropped from 96% under dry conditions to 86% under wet conditions (Rhode et al., 1980). A 6-m vegetative buffer strip composed of trees, shrubs, and grass almost completely removed terbuthylazine from runoff (Vianello et al., 2005). Oats as a strip crop below corn reduced atrazine runoff losses by 91% and 65% after applications of 2.2 and 4.5kg/ha, respectively (Hall et al., 1983). Atrazine and metolachlor concentrations in runoff were reduced 83-94% and 82-96%, respectively, with 4.3- and 8.5-m vegetative filter strips (Barone et al., 1998). 

Mickelson, S.K. and J.L. Baker (1993). Buffer strips for controlling herbicide runoff losses. Paper No. 932084. 1993 International Summer Meeting, American Society of Agriculture Engineers, Spokane, WA. 

The heptachlor, dieldrin, and toxaphene examples show that foliage and soil residue dissipation data can be used to estimate the amounts of residues volatilized when no significant degradation or runoff losses are incurred. For toxaphene, residue analyses indicated that 80% of the foliage residue and 51% of the top soil residue was lost by volatilization within ca 50 days. This is considerably more than the 24% vaporization loss reported for toxaphene within 90 days in a model chamber (8), but is comparable to foliage-applied heptachlor and dieldrin (75) both of which overlap in volatility with components of the toxaphene mixture. 

Data presented as in Figure 1 has the advantage of accentuating differences due to spalling and runoff losses. These differences result in points which lie below the line describing the short-term data. 

With this approach, spalling and runoff losses do not affect the computation of the slope. On the other hand, the precision of the wet chemical measurements is lower than for the gravimetric measurements and slopes computed by Equation 8 are not as well defined as those from Equation 6. In the limit when S =Rl=0, these two approaches to computing the slopes give similar results. 

The zinc losses for longer exposures. Figure 6, show a decidedly different result. Here there is an increasing trend of zinc loss from the corrosion film as the hydrogen ion load increases. A least squares fit of the data yields the following relationship between the zinc runoff loss, Zn/dm ), and the hydrogen ion... 

Copper. Plots of film weight versus metal loss for 1- and 3-month exposures of 110 copper generally show a linear relationship between film weight and metal loss. If 1-year exposures are included in the plot they will be scattered and fall below the line established by the 1- and 3-month exposures. This may be an indication of runoff losses in longer exposures. The lines based on short-term data had slopes of 1.12, 1.19, 1.10, and 1.08 for the North Carolina, New Jersey, New York, and District of Columbia sites, respectively, when based on gravimetric data. Equation 6. 

The District of Columbia data points exhibited somewhat greater scatter then the other sites, which could represent increased runoff loss for these samples. 

Runoff Losses Due to Hydrogen Ion Loading. Runoff losses from zinc, and presumably galvanized steel, are dependent upon hydrogen ion load in 3- and 12-month exposure. Such an effect is not apparent in 1-month exposures. Hydrogen ion dissolves zinc carbonate, perhaps the major constituent of the corrosion film, by the reaction... 

The calibrated half-life for aldicarb is longer than the half-life which was calculated based on field data (Table II). This occurs because runoff loss of aldicarb as well as leaching below the depth of sampling are not accounted for in field-calculated half-lives, which are calculated based only on aldicarb remaining at each sampling date. An additional possible avenue of loss is plant uptake of aldicarb. However, the total amount of uptake was not estimated in the field, nor was it simulated in PRZM. As such, it can be considered that plant uptake loss was "lumped" in the calibrated (and calculated) half-lives. 

Losses of K through erosion of clays from the soil surface can be very substantial. Few measurements of runoff loss have apparently been done but these losses... 

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