摘要:

The adsorption, desorption, and degradation of endosulfan (1,2,3,4,7,7‐hexachlorobicyclo[2,2,l]‐2‐heptene‐5,6‐bisoxymethylene sulfite) in two major tropical soils from Thailand were studied. Each soil‐type, Rangsit lowland soils (Rangsit series) and Phrabat upland soils (Pakchong series), were sub‐divided into surface or plow layer, 0–20 cm depth, and subsoils, 20–40 cm depth. Adsorption was determined using 24 h batch equilibrium, with five different concentrations of14C labelled endosulfan ranging from 1.04 to 16.64 ng/mg soils. Adsorption coefficient values(Kads)as by Freundlich's model ranged from 0.02 to 0.20. Higher adsorption coefficients were measured in Rangsit soils as compared to Phrabat soils. Desorption as attributed to hysteresis was also measured. Desorption coefficient values(Kjes)were higher than adsorption(Kads)in each study. Degradation of endosulfan was through microbial process. Little abiotic degradation was measured in sterile soil sample. Measured degradation rates were highest in Phrabat plow layer and subsoil. However, total degradation after 98 days was less than 20 % of initial application rate. Results indicate that applied endosulfan would be persistent or slow to degrade in the soils studied.

ISSN:0360-1234    

DOI:10.1080/03601239809373140

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The adsorption/desorption of amitraz by suspended river sediment particles in an aqueous medium was studied in terms of a model which assumes the adsorption/desorption equilibrium nX + S ðí SXn(W)ðí SXn(sed),where X and S represent the pesticide molecule and suspended particle respectively, SXn(w)is the pesticide‐particle complex (in suspension), and n is the number of pesticide molecules associated with a single adsorption site. According to this model the apparent adsorption/desorption equilibrium constant, K’, is given bywhere [X]adsis the concentration of X in the adsorbed state in suspension found in the sediment after settling, [X]eis the concentration of X in solution at equilibrium, and [SX]wis the concentration of the pesticide‐adsorption site complex in suspension at equilibrium. Values of 111”; 19, 0.26"0.03 and ‐11.6"0.5 KJmole‘1were obtained for K1, n, and DG’ (the apparent adsorption/desorption free energy) for the adsorption of amitraz by the river sediment used.

ISSN:0360-1234    

DOI:10.1080/03601239809373141

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Metabolism of carbofuran in pure liquid cultures ofA. nigerandF.graminearumwas investigated. Carbofuran and its metabolites were analyzed by HPLC and TLC. The average recoveries of carbofuran, 3‐hydroxycarbofliran, 3‐ketocarbofuran, and 3‐ketocarbofuran phenol from fungi media were found to be 88.65, 86.19, 75.48, and 80.48%, while their detection limits were 0.035, 0.031, 0.015 and 0.140 ppm, respectively. The data showed thatA. nigerwas capable of degrading carbofuran more faster thanF. graminearum.Carbofuran disappeared biexponentially from the liquid culture media of both fungi. The terminal half‐life values of carbofuran were 10.4 and 12 days in the media ofA. nigerandF.graminearum,respectively. The amounts of carbofuran reached 15.56 and 19.71% of the applied dose after 21 days in case ofA. nigerandF. graminearum,respectively. Carbofuran was biotransformed to 3‐hydroxycarbofuran, 3‐ketocarbofuran, and 3‐ketocarbofuran phenol. The percentages of the major metabolite, 3‐hydroxycarbofuran were 47.72 and 7.77% in case ofA. nigerandF. graminearumafter 21 days, respectively.

ISSN:0360-1234    

DOI:10.1080/03601239809373142

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this investigation methyl bromide, a widely used soil fumigant, was investigated with respect to workers exposure and environmental fortification at the greenhouses of Thessaloniki area, Northern Greece. By means of personal and environmental air sampling through charcoal, methyl bromide concentration was measured by gas chromatography using a capillary OV‐1 column at 45° C and flame ionization detector (FID). Personal air sampling for two workers showed that the levels of exposure to methyl bromide were 89 and 92 mg/m3respectively. These values exceeded the safety limits. The mean maximum and mean minimum concentrations in the environmental air samples inside the greenhouse, for 8 hours duration, were 142 mg/m3and 4 mg/m3, respectively. These concentrations were determined within four and eleven days after the application of methyl bromide.

ISSN:0360-1234    

DOI:10.1080/03601239809373143

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The Solid Phase Micro‐Extraction (SPME) technique was applied to analyze chlorpropham in potatoes and amitraz in honey. The homogenized sample, suspended in water and stirred, was extracted with a 100 μm thick polidimetylsiloxane fiber and desorbed into the injection port of a gas chromatograph/mass‐spectrometer (quadrupole) operating in single ion monitoring. Sensitivities down to 0.01 mg/Kg and linear responses in the range of 0.01–0.1 mg/Kg were obtained. The results of SPME pesticide residue analysis in potatoes corresponded to those obtained with a traditional multiresidue method.

ISSN:0360-1234    

DOI:10.1080/03601239809373144

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Toluene and a peat soil (93% organic matter content) were used to investigate time‐dependence of isotherm nonlinearity and to gain a better understanding of sorption mechanisms of organic chemicals in soil organic matter (SOM). Isotherms were constructed using batch mixing technique at a series of contact time intervals. Toluene analysis was performed using liquid scintillation counting and sorption data were fitted with the Freundlich model (S = KFCN,whereSandCare sorbed and solution concentrations, respectively,KFandNare constants). Isotherms at all contact times were nonlinear(N= 0.84–0.93), indicating a distribution of site energies in SOM. TheKFvalues increased (from 54 to 75) with contact time. Nonlinearity also increased (i.e.,Ndecreased) with increasing contact time, suggesting that energetic sites and condensed domains were relatively concentrated within the SOM matrix. These results are consistent with dual‐mode model of sorption in SOM proposed earlier. In this model both solid‐phase dissolution and site‐filling (adsorption‐like) mechanisms were shown to take place and the competition took place only in the site‐filling (or condensed) domains.

ISSN:0360-1234    

DOI:10.1080/03601239809373145

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Cadmium (Cd) influence onChamomilla recutita(L.) Rauschert growth and efficiency of eliminating substrates (Zeolite and Ekofert) was studied in a pot experiment. The influence of extreme dose (25 mg Cd.kg‐1of soil) caused very high accumulation in anthodia. Inhibition effect of cadmium was observed in the number and yield of anthodia per plant; height of plants and weight of anthodia were not influenced. Soil application of eliminating sorbents decreased concentration of Cd in chamomile anthodia by 27% or 19%, respectively. It also increased the number and yield of anthodia. No influence of cadmium on apigenin glucosides percentage in ligulate flowers of anthodia was found.

ISSN:0360-1234    

DOI:10.1080/03601239809373146

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:0360-1234    

DOI:10.1080/03601239809373147

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:0360-1234    

DOI:10.1080/03601239809373139

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor