摘要:

Wheat grain was treated with radiolabeled diflubenzuron at 100 ppm and stored for various periods; up to 6 months. The grain was surface washed, Soxhlet‐extracted with methanol, and the residues determined. A relative constant amount of bound residues (4%), i.e., non‐extractable radioactivity, was found 4 months after application and remained constant. More than 97% of the extractable radioactivity in the grain after 6 months was identified as diflubenzuron. When the bound residues were fed to rats, 47% of the administered dose was eliminated via the urine and the remainder via feces within 96 h. Diflubenzuron was the major component in the urine. Adding bound residues to housefly media resulted in a dose‐dependent mortality of housefly pupae. Bound residues were biologically active, preventing the emergence of adult houseflies. Supercritical fluid extraction of the bound residues extracted 922 and 96% of the radioactivity associated with grain and feces, respectively. Only diflubenzuron was present in these extracts.

ISSN:0360-1234    

DOI:10.1080/03601239209372769

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Surface microrelief may influence the fate of agrichemicals in the soil by influencing surface water flow. The objective of this experiment was to determine the impact of agrichemical placement on agrichemical movement in a ridge tillage system. Alachlor, bromide, and calcium nitrate (15N labeled) were applied above fifteen grid lysimeters to either the ridge top or valley area of a ridge tillage system. The grid lysimeters allowed temporal and spatial fractionation of leachate. Sixteen hours after agrichemical application, 15 cm of water was applied with a rainfall simulator. During the simulated rainfall, water flowed from the ridge top to the valley and then into the soil profile. Surface water flow increased the amount of water collected in lysimeters placed under valley areas when compared with ridge areas, which in turn increased the movement of N fertilizer, bromide, and alachlor through the soil profile.

ISSN:0360-1234    

DOI:10.1080/03601239209372770

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Enhanced biodegradation of carbofuran (2, 3‐dihydro‐2, 2 dimethyl‐7‐benzofuranyl methyl carbamate) is an economically significant, but poorly understood, mlcrobial phenomenon in soil. A series of experiments was conducted to examine short term changes in soil bacterial populations stimulated by carbofuran application at field rates. In the field experiment, commercially formulated carbofuran and butylate (S‐ethyl diisobutyl carbamothioate) were applied at 5.6 kg al ha‐1and 8.4 kg ai ha‐1, respectively, on a soil (Putnam silt loam) exhibiting enhanced degradation of caibofuran. In laboratory studies, technical grade carbofuran (20 mg kg‐1soil) was applied to samples of the field soil. Bacterial populations were estimated using non‐selective (tryptic soy agar) and selective media containing carbofuran or butylate. Largest population increases in pesticide‐treated soil were observed between 7 and 15 days after treatment (DAT) compared to populations in non‐treated soil. Significant increases (P<0.05) in total bacterial populations and presumed carbofuran‐degraders due to carbofuran application were associated with increased populations ofPseudomonasspp. andFlavobacterlumspp. Application of carbofuran appeared to provide a competitive advantage to these species over actinomycetes persisting beyond 20 DAT. Growth responses of bacteria to carbofuran in the Putnam soil were compared to those in a native prairie soil (Mexico silt loam), which exhibited a much slower rate of carbofuran degradation. Bacterial population response to carbofuran was measurable, but small and short‐lived. Perpetuation of the enhanced degradation phenomenon may lie in a persistent pesticide‐induced competitive advantage given to a very small segment of the microbial population. This advantage may not be detectable after 20 days using conventional plating techniques

ISSN:0360-1234    

DOI:10.1080/03601239209372771

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The acute toxicity of endosulfan and diazinon to the freshwater rotiferBrachionus calvcifloruswas determinated after 24 hours exposure to these toxicants. The mean 24 hr‐LC50 values were 5.15 and 29.22 mg/L for endosulfan and diazion respectively. Based on these results, four sublethal concentrations were chosen to determined the median lethal time (LT50) at each concentration of toxicant tested. We also used a control with the solvent (acetone).

ISSN:0360-1234    

DOI:10.1080/03601239209372772

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Aerial spray deposits were measured on collection surfaces using two methods: spectrophotometry for Day‐Glo®, a fluorescent dye tracer; and gas‐liquid chromatography (GLC) for triethyl phosphate (TEP), a chemical tracer. The spray mix consisted of glycerol, water, Atlox®3409F and the two tracers. It was sprayed on May 4, 1988 at 5 L/ha over an 8‐ha flat area of the Sault Ste. Marie airport, using a Cessna 188 aircraft equipped with rotary atomizers. Balsam fir‐shaped aluminum branch tips, natural fir needles and glass plates were used to collect deposits.

ISSN:0360-1234    

DOI:10.1080/03601239209372773

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A still‐air, controlled experiment showed that the use of spherical targets resulted in a slight underestimate (7%) of the deposition of spray droplets (mean diameter ≈ 180μ). This error was attributed to interception by the wire supports suspending the spheres. Comparison of sphere and flat card catch data from a USDA APHIS open field, aerial spray trial demonstrates that the impaction on the cards decreases as the wind speed increases and that they are generally unsuitable for pesticide accountancy. The spheres only have small errors when used to sample mass flux of pesticide spray.

ISSN:0360-1234    

DOI:10.1080/03601239209372774

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The toxicity, accumulation, and elimination of diazinon were investigated for the european eel,Anguilla anguilla.The 24, 48, 72 and 96‐h median lethal concentrations (LC50) were 0.16, 0.11, 0.09 and 0.08 mg/L, respectively. Fish exposed to sublethal concentration (0.042 mg/L) accumulated diazinon in liver and muscle tissues. Bioconcentration factors (BCF) of diazinon were 1850 in liver, and 775 in muscle over the 96‐h exposure period. Upon removal from diazinon containing water the contaminated fish rapidly eliminated diazinon. The excretion rate constants of this insecticide were 0.108 h‐1for liver and 0.016 h‐1for muscle. Diazinon half‐lives were 16.6 and 33.2 hours for liver and muscle, respectively.

ISSN:0360-1234    

DOI:10.1080/03601239209372775

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor