摘要:

Distribution and dissipation of metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐l‐methylethyl) acetamide] in a soil of Montpellier were evaluated in laboratory conditions for 8 weeks using 100 cm PVC pipes. The half‐lives of metolachlor varied from 31 to 54 days according to the application dose (1.2, 4.5 and 9 kg a.i./ha respectivelly). The rate of herbicide migration increased with stronger dose. Adsorption and desorption of metolachlor were studied in the same soil at three difierent depths. Soil Freundlich adsorption coefficients (Kfa) were 1.0,0.7 and 0.6 for 0 to 10, 10 to 50 and 50 to 95 cm depths respectively. Desorption coefficients (Kfd) varied more slightly (3.6 ‐ 3.9). Ratio soil quantity/water volume may influence adsorption parameters.

ISSN:0360-1234    

DOI:10.1080/03601239309372845

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The adsorption of two cationic pesticides on the soluble part of natural and artificial humic substances, and their mechanisms of interaction, have been studied using the equilibrium dialysis method. Paraquat and chlordimeform in diverse concentrations have been used. A natural fulvic acid extracted from a spodosol soil, a commercial humic acid and polymaleic acid vere used as comparison. Chlordimeform adsorption data from this work are higher than those obtained in a previous paper without dissolving the humic substances. Paraquat isotherms always present values lower than chlordimeform ones. Natural fulvic acid adsorbs more than the commercial humic substance for both pesticides.

ISSN:0360-1234    

DOI:10.1080/03601239309372846

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

This paper describes the development of apparatus suitable for direct supercritical fluid extraction of organics from water. Results are presented for the extraction of pentachlorophenol present in water at concentrations of the order of 0.1 ppm. The effect of changes in apparatus design and supercritical fluid flow rate on recovery are discussed.

ISSN:0360-1234    

DOI:10.1080/03601239309372847

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Cyclodiene insecticides, hexachlorocyclohexanes, pyrethroids, bicyclophosphates, the bicycloorthocarboxylate insecticides and some of their metabolites and environmental degradation products are central nervous system toxicants with high specific binding affinity to the chloride channel of the γ‐ aminobutyric acid (GABA)Areceptor‐ionophore sites. [35S] tertiary‐butylbicyclophosphorothionate (TBPS) with specific activity higher than 60 Ci/mmole has a high binding affinity to the same sites and is now commercially available and can be used to label the GABAAreceptor for the development of a radioreceptor assay technique. The GABA receptor was prepared by ultra centnfugation and dialysis of brain homogenates of either cow, goat, rat or catfish. The receptor was then labeled with [35S] TBPS and the assay was conducted by measuring the displacement of radioactivity following incubation with samples containing the analytes. A radioreceptor assay protocol was developed to measure the amount of the α‐endosulfan in blood samples. The assay was extremely sensitive, and can detect 0.2 nM of endosulfan at a level equivalent to 0.08 ppb or 8x10‐11gm of endosulfan in each ml of the blood samples.

ISSN:0360-1234    

DOI:10.1080/03601239309372848

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Acute toxicity of paraquat (PQ) and its effects on brain acetylcholinesterase (AChE) activity of a freshwater fish males and femalesBryconamericus iheringiiwas evaluated. The LC50 values at 24, 48, 72 and 96 hs were: 40, 47; 24, 17; 22, 15 and 20, 21 mg of PQ/L respectively.

ISSN:0360-1234    

DOI:10.1080/03601239309372849

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Succinate ‐14C‐ malathion penetrates readily into soybean seeds. The total internal residues inside the seeds amounted to 58–65% of the applied dose after 30 weeks, of which 8–9 % were in the form of bound residues. The major part of the internal methanol extractables are chloroform soluble metabolites which include malathion (about 60%), monocarboxylic acid (15%) and its decarboxylation product (8%). The water soluble metabolites contained only one radioactive substance, namely malathion dicarboxylic acid.

ISSN:0360-1234    

DOI:10.1080/03601239309372850

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Deoxynivalenol (DON) is one of the major mycotoxins produced byFusariumfungi, and is known to affect feeding behaviour in economically important animals. In this study the effect of low‐level DON on cerebral spinal fluid (CSF) neurotransmitter concentrations, as a reflection of altered brain activity, was investigated in swine. Animals were given repetitive doses (6) at 3 0 min intervals, either intravenously (iv) (10 μg/kg) or intragastrically (ig) (30μg/kg). Serial CSF samples were collectedviaa novel permanent indwelling catheter placed intracerebrally, and changes in catecholamine levels monitored. Results showed a rapid and sustained increase in 5‐hydroxyindoleacetic acid (5HIAA) occurred following ig administration, remaining elevated for up to 20 hr post‐dosing, and to a lesser extent after iv dosing, lasting up to 6 hr post‐dosing. This was indicative of increased CNS serotoninergic activity and indicative to the theory that links elevated brain serotonin turnover to a decrease in feed intake. Also observed were alterations in dopamine (DA) metabolism. Following ig dosing, a delayed increase in homovanillyl alcohol (HVOL) suggested an enhancement of the dopaminergic response occurred as serotoninergic activity diminished. Following iv dosing, a rapid drop in homovanillic acid (HVA) levels alluded to a more direct toxic effect, possibly acting as an inhibitor of DA‐metabolizing enzymes.

ISSN:0360-1234    

DOI:10.1080/03601239309372851

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Phosphorylation is an indispensable process for energy and signal transduction in biological systems. AlCl3at 10 nM to 10 uM range activatedin‐vitro[γ‐32P)ATP phosphorylation of the brain (tau) T protein in both normal human orE.coliexpressed T forms; in the presence of the kinases P34, PKP, and PKC. However, higher concentrations of ALCl3inhibited the T phosphorylation with P34, PKP, and PKC to a maximum at 1 mM level. AlCl3at 100 uM to 500 uM range induced non‐enzymatic phosphorylation of T with γ‐ATP, γ‐GTP, and α‐GTP. AlCl3activated histone phosphorylation by P34 in a similar pattern. The hyperphosphorylation of T by Al3+was accompanied by molecular shift and mobility retardation in SDS‐PAGE. This may demonstrate the mechanism of the longterm neurological effect of Al3+in human brain leading to the formation of the neurofibrillary tangles related to Alzeheimer's disease.

ISSN:0360-1234    

DOI:10.1080/03601239309372852

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor