摘要:

The spatial distribution of hexazinone and two primary metabolites were measured in forest soil for two years following the aerial application of a granular formulation, PRONONE 10G, in northern Alberta. Residues were quantified using solid‐phase extraction and capillary gas chromatography. Initial deposition rates of two hexazinone treatments averaged 2.3 ± 0.5 and 4.1 ± 0.8 kg/ha for each triplicated plots. One year after application, residues of hexazinone averaged 0.25 ± 0.09 and 0.40 ± 0.02 kg/ha in 2.3 and 4.1 kg/ha treatment, respectively, in the 0–10 cm surface soil; and were distributed vertically in soil depths of 0–10, 10–20, and 20–30 cm at ratios of 10:11:2 and 10:5:2, respectively, in 2.3 and 4.1 kg/ha treatment. Metabolites A and B amounted to 15 and 30% of hexazinone, respectively. Two years after application, the vertical movement of hexazinone in soil was quantifiable to the 40‐cm depth in both 2.3‐ and 4.1‐kg/ha treatment plots. Trace amounts of hexazinone were detected at 130 cm only in the 2.3‐kg/ha plot, which is likely due to the more freely downward movement of hexazinone to deeper horizons along decayed root channels.

ISSN:0360-1234    

DOI:10.1080/03601239209372804

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Standard nonlinear regression techniques were used to fit nine data sets (21 points, cv = 0.001), derived from models that have been used to describe pesticide disappearance from soil, to each of the nine models. Goodness‐of‐fit was assessed using the residual mean square. Four models (3 four parameter and 1 five parameter) were found to be identical in their fit to each of the nine data sets. Additional data sets (21 and 8 points with cv's of 0.001, 0.01, 0.1 and 0.2) were generated for the remaining five models (1 four parameter, 1 three parameter and 3 two parameter) to evaluate the effect of number of observations and noise level on the data‐to‐model identifiability and the parameter estimates. The number of 21 point data sets uniquely identifiable with the model used to produce the data were 5, 3, 2 and 0 at cv's of 0.001, 0.01, 0.1 and 0.2 respectively. Similar results were observed for the 8 point data sets. At least one parameter was poorly defined in the three and four parameter models by the 21 point data set and in all five models by the 8 point data set with cv = 0.1. Five sets of observations for which one of the nine models was originally proposed were fitted to each of the five selected models, in addition to the original model. In all cases, simpler or previously described models fit the data as well as or better than the models proposed by the authors. At least one parameter was poorly estimated in most cases. Twenty‐six of the 45 sets of observations evaluated in the description of a recently proposed model based on spatial variability were fitted to each of the five selected models. In 17 cases, two parameter models fit the data as well as or better than the three parameter model proposed. The implications of these observations on the role of modeling in the study of pesticide disappearance from soil is discussed.

ISSN:0360-1234    

DOI:10.1080/03601239209372805

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A model was developed to predict the evaporation rate of pesticides that are sprayed aerially. Deposit data collected fromBacillus thuringiensis(Bt) spray field trials and analyzed by washoff and ¡mage analysis methods were used to test the model. Results showed that the model with a mode based on the theoretical evaporation formula of a droplet of pure water tended to overpredict the evaporation rate of Bt by 11 % on average.

ISSN:0360-1234    

DOI:10.1080/03601239209372806

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Laboratory tests were conducted with eight herbicides, atrazine, butylate, ethalfluralin, imazethapyr, linuron, metolachlor, metribuzin and trifluralin, applied to a loamy sand at rate of 10 μg/g to determine if these materials caused any serious effects on microbial and enzymatic activities related to soil fertility. Some herbicides showed an effect on bacteria and fungi for the first week of incubation, but, subsequently, the populations returned to levels similar to those obtained in the controls. After several herbicide treatments there appeared to cause a slight depression of nitrification. Sulfur oxidation was better than that obtained with untreated soil in all treatments. Oxygen consumption was increased significantly after 96 hr incubation with atrazine. The soil dehydrogenase and amylase activities were inhibited by ethalfluralin treatment respectively for 1 wk and 1 day, and p‐nitrophenol liberation was inhibited for 2 hrs by all herbicide treatments. Results indicated that the herbicidal treatments at the level tested were not drastic enough to be considered deleterious to soil microbial and enzymatic activities which are important to soil fertility.

ISSN:0360-1234    

DOI:10.1080/03601239209372807

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Field trials were conducted to measure translocation of pesticides by summer and winter forage/pasture species from soil containing aged residues of heptachlor and, to a lesser extent, dieldrin. Substantial amounts of heptachlor epoxide, and lesser amounts of y‐chlordane were translocated to plants from contaminated soil. Residue levels varied with crop species and stage of plant development. In summer crops residues were higher in soybean> cowpeas>lab‐lab>Sorghum>millet>sweet saccaline at the grazing and mature stages.

ISSN:0360-1234    

DOI:10.1080/03601239209372808

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In the present study the biotransformation of phenanthrene in the rat and guinea pig was investigated.14C‐labelled phenanthrene was administered by gavage in com oil to Sprague‐Dawley rats (10 mg/kg b.w./day) and guinea pigs (10 mg/kg b.w./day). Urine and feces were separately collected for the determination of the radioactivity content, and pooled urine was used for the analysis of metabolites. Phenanthrene was metabolized by the rat and guinea pig to free hydroxylated phenanthrenes and their conjugates. The percentages of conjugates, expressed as the total urinary radioactivity, were 39% glucuronides, 24% sulfates and 18% cysteinylglycine for rats; and 39% glucuronides, 23% sulfates and 28% cysteinylglycine for guinea pigs. Enzymatic hydrolysis of glucuronides and sulfates resulted in the formation of free 1,2‐, 3,4‐ and 9,10‐dihydrodiols of phenanthrene and 1‐, 2‐, 3‐, and 4‐hydroxyphenanthrene in both species.

ISSN:0360-1234    

DOI:10.1080/03601239209372809

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Effect of repeated oral administration of hexachlorophene (HCP) on glycolytic and oxidative pathways was studied in the rat brain. The rats were divided into three batches of six in each batch. The first batch was treated with paralytic dose (60 mg. kg‐1. day‐1) of HCP for 7 days. The second batch of animals was treated with sublethal dose (18 mg. kg‐1. day‐1) for 7 days. The third batch of animals was served as the age matched controls which received vehicle (corn oil) only. The glycolytic and oxidative metabolism of carbohydrates was significantly inhibited in the brain of rat during HCP treatment and the inhibition was more pronounced in paralytic dose treatment as compared to sublethal dose treatment. The inhibition of NADP‐isocitrate dehydrogenase coupled with glucose 6‐phosphate dehydrogenase indicates reduced generation of NADPH2and pentoses for the synthesis of fatty acids and nucleotides.

ISSN:0360-1234    

DOI:10.1080/03601239209372810

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The bran toxic baits (0.5 % w/w) of five oxime carbamate pesticides; aldicarb, aldoxycarb, methomyl, oxamyl and thiofanox were tested for their molluscicidal activity againstTheba pisanasnails under Laboratory conditions. In addition, thein vivoeffects of these compounds on seven vital enzymes namely Acetylcholin‐esterase (AchE), glutathion‐S‐transferase (GST), glutamic oxlaoacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), acid phosphatase (AcP), alkaline phosphatase (AIP), and adenosine triphosphatase (ATPase) activities of the snail tissue were also investigated after 1,3, and 5 days of exposure. The results showed that methomyl was the most potent candidate, whereas thiofanox was the least effective one against the snails. LT50’s values of aldicarb, aldoxycarb, methomyl, oxamyl and thiofanox were 5.77, 4.69, 2.31, 3.97 and 6.67 days, respectively. Results of the potency of the tested pesticides against AchE activity were in harmony with the toxicity of these compounds to snails. AchE, AcP, and AIP activities were inhibited by the tested pesticides. GST activity was inhibited by aldicarb but stimulated by oxamyl and thiofanox. Methomyl and oxamyl lead to significant elevation of GOT and GPT, whereas thiofanox treated snail induced a reduction of both enzymes activities. Aldicarb and aldoxycarb caused significant induction of ATPase activity.

ISSN:0360-1234    

DOI:10.1080/03601239209372811

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor