Water Research (Impact Factor: 5.53). 09/1998; 32(9):2814-2820. DOI: 10.1016/S0043-1354(98)00021-9
The sorption and leaching processes of diuron from a 0.02 M CaCl2 aqueous solution at 25°C, by a calcareous soil from the Southeastern of Spain after organic carbon (OC) amendment with a commercial peat (from 0.18% to 4.61%) have been studied by using batch and soil column experiments. The experimental sorption isotherms may be classified as L type of the Giles classification which suggests, in general, a moderate affinity of the diuron molecules by the active sites of the adsorbents. Nevertheless, according to the slope of the initial portion of these isotherms, the affinity increases as the organic matter content increases. In order to calculate the adsorption capacity (Kf) of the samples for the herbicide diuron, the experimental data point were fitted to the Freundlich equation. The Kf values ranged between 2.17 mg kg−1 for the original soil (containing 0.18% OC) and 34.28 mg kg−1 for the peat-amended sample containing 4.61% OC. The breakthrough curves and distribution of diuron along the soil profile, obtained from the step-function type and pulse type experiments by using the soil column studies, indicate that the amount of diuron retained range from 359.3 mg kg−1 for the column filled with the original soil to 439 mg kg−1 for that filled with the peat-amended soil containing 4.61% OC. The amount of diuron desorbed (373.0 mg kg−1) from the soil containing the higher percentage of organic carbon (4.61%) was greater than that desorbed (300.8 mg kg−1) from the original soil, which might be due to the joining of diuron to the soluble fraction of the organic matter moving through the column.
[Show abstract][Hide abstract] ABSTRACT: Sorption of acetamiprid ((E)-N1-[(6-chloro-3-pyridyl)methyl]-N2-cyano-N1-methylacetamidine), carbendazim (methyl benzimidazol-2-ylcarbamate), diuron (N-(3,4-dichlorophenyl)-N, N-dimethyl urea) and thiamethoxam (3-(2-chloro-thiazol-5-ylmethyl)-5-methyl-[1,3,5]oxadiazinan-4-ylidene-N-nitroamine) was evaluated in two Brazilian tropical soils, Oxisol and Entisol, from Primavera do Leste region, Mato Grosso State, Brazil. To describe the sorption process, batch experiments were carried out. Linear and Freundlich isotherm models were used to calculate the K(d) and K(f) coefficients from experimental data. The K(d) values were utilized to calculate the partition coefficient normalized to soil organic carbon (K(oc)). For the pesticides acetamiprid, carbendazim, diuron and thiamenthoxan the K(oc) (mL g(- 1)) values ranged in both soils from 98 - 3235, 1024 - 2644, 145 - 2631 and 104 - 2877, respectively. From the studied pesticides, only carbendazim presented correlation (r(2) = 0.82 and p < 0.01) with soil organic carbon (OC) content. Acetamiprid and thiamethoxam showed low sorption coefficients, representing a high risk of surface and ground water contamination.
Journal of Environmental Science and Health Part B 06/2007; 42(5):499-507. DOI:10.1080/03601230701389439 · 1.20 Impact Factor
"Indeed, the DOC content was higher in the grape-seed layer (3.7 mg DOC per g of soil) than in the vegetated layer (2.6 mg DOC per g of soil). Gonzales-Pradas et al. (1998) have shown that diuron mobility could be promoted by incorporation of peat in the soil surface layer inducing a DOC enhancement in the leachates. At the end of the monitoring period, the amounts of DCPMU (based on the amount of diuron applied) were greater in the leachates of the rendosol and bare calcosol (0.13% and 0.12% respectively) than in those of the calcosol MS and vegetated calcosol (0.07% and 0.05% respectively) (Fig. 3). "
[Show abstract][Hide abstract] ABSTRACT: Field studies monitoring herbicide pollution in the vineyards of Burgundy (France) have revealed that drinking water reservoirs are contaminated with several pre-emergence herbicides. An assessment of the leaching of two such herbicides, diuron and oryzalin, was therefore performed using lysimeters, under outdoor conditions, from May 2001 to May 2002. Four vineyard soils from Vosne-Romanée (Burgundy) were chosen along a topolithosequence: a rendosol and three calcosols. After 673 mm of rainfall, greater amounts of diuron than oryzalin were measured in percolates: respectively 0.10-0.84% and 0.02-0.43% of applied herbicide, depending on soils. Measurements for diuron metabolites detected greater amounts of DCPMU than DCPU in the percolates: respectively 0.05-0.13% and 0-0.04% of the applied diuron. At the end of the monitoring period, more residues of diuron than oryzalin were recovered in the soil profiles: respectively 4.6-9% and 1.4-4.4%. The oryzalin residues were found mainly in the upper 10 cm of soil columns, whereas diuron residues were present in the whole core. The mobility of both oryzalin and diuron seems fairly well-related to soil organic carbon content; the mobility of diuron is also related to soil texture (sand and coarse material contents). Under such experimental conditions, this study confirms that diuron leaching, and therefore potential groundwater contamination, is greater than that of oryzalin.
[Show abstract][Hide abstract] ABSTRACT: The purpose of the study was to det ermine the process of adsorption an d desor ption of carbofuran at two different temperatures in t wo different types o f M alaysian soi ls. The t wo types of soil used in t his study were clay (high organic carbon content) and s andy clay (low organic carbon c ontent). The recovery rates of carbofuran from sandy clay and clay soils were 98.7 and 76.1% respectively. The adsorption of carbofuran onto the soil corresponded well with t he Freundlich isotherm. The results showed that adsorption of carbofuran decreases with i ncrease i n t emperature at low i nitial concentration ( 10 µg). However, at higher initial concentrations (eg 50 µg), the influence of temperature on ads orption i s not significant. The results show that the percentage adsorption of carbofuran is hi gher in c lay than in s andy clay soils. The percentage carbofuran desorbed into the aqueous p hase ranged from 57.4% to 89.8% in sandy c lay a nd 51.7% to 75.9% in clay. The results clear ly s howed that carbofuran m olecules were b ound weakly t o clay and sandy cl ay so ils.
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