摘要:

The potential for14C‐fluometuron(N,N‐dimethyl‐N'‐[3‐(trifluoromethyl)‐phenylurea]) degradation in unialgal cultures of 15 strains of green algae and 2 species of cyanobacteria (blue‐green algae) was investigated. Eight of 15 algal strains(Ankistrodesmus, Chlorella, Pediastrum, ScenedesmusandSelenastrumspecies) metabolized fluometuron viaN‐demethylation to desmethyl fluometuron. The highest fluometuron‐demethylation activity was observed in the generaAnkistrodesmus (A. falcatusandA.cf.nannoselene)andSelenastrum (S. capricormitum, S. gracileandS. mimitum)with complete sequential demethylation to trifluoromethylphenylurea observed in certain strains. Low levels of fluometuron‐demethylating activity in certain algal strains may be due to herbicide toxicity. Algal strains(AnkistrodesmusandSelenastrumsp.) that metabolize fluometuron viaN‐demethylation also transform the herbicide atrazine (6‐chloro‐N‐ethyl‐N‘’‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine) byN‐dealkylation to deethylatrazine, however this activity is several‐fold lower than fluometuron‐demethylation activity. Our study indicates that algae have the potential to contribute to herbicide transformations in aquatic environments viaN‐dealkylation transformations.

ISSN:0360-1234    

DOI:10.1080/03601239809373160

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Trifluralin [2,6‐dinitro‐N,N‐dipropyl‐4‐(trifluoromethyl)benzenamine], metolachlor [2‐chloro‐N‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl) aceta mide], and metribuzin [4‐amino‐6‐(1,1‐dimethylethyl)‐3‐(methylthio)‐1,2,4, ‐triazin ‐5(4H)‐one] were selected to study adsorption and leaching potentials related to pollution on Commerce silty clay loam soil near Baton Rouge, Louisiana. At a 1:10 soil/water ratio, the Koc values for trifluralin, metolachlor and metribuzin were 875, 135, and 96, respectively. Leaching of these herbicides was evaluated in soil columns (5.4 cm i.d. × 26 cm long). Total recoveries of the herbicides applied to the soil column were 73.1% ±4.1%. When the soil columns were leached with three pore volumes of water, the distributions of trifluralin in soil and leachate were 99.993% and 0.007% of the total recoveries, respectively. The distributions of metolachlor was 65.27% in soil and 34.7 % in leachate. The distributions of metribuzin was 11.42% in soil and 88.58% in leachate. The results showed that metolachlor and metribuzin were readily leached, while trifluralin was strongly adsorbed to soil. Leaching of three herbicides in the soil column followed the leaching trends of their calculated leaching indices 1.41 × 104, 4.18 × 106, and 3.38 × 108for trifluralin, metolachlor, and metribuzin, respectively. The results of the study demonstrated the potential of pollution for metolachlor and metribuzin to be leached into the ground water in soils with shallow aquifer.

ISSN:0360-1234    

DOI:10.1080/03601239809373161

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Adsorption of the imidazolinone herbicides imazapyr, imazethapyr and imazaquin have been studied on two humic acids and on ten soils. On humic acids, adsorption was promoted by low pH values and was in the order imazapyr < imazethapyr < imazaquin corresponding to the increasing lipophilicity of the molecules, in agreement with the octanol‐water partition coefficient. On soils, the correlations between the Freundlich coefficient Kf of the isothermes and the soil characteristics provided evidence that for each herbicide studied, the soil components mainly involved in the process were organic matter, amorphous iron oxides and iron‐organic matter complexes. Adsorption was promoted by low pH values. However, the order of adsorption in soils was imazapyr ≈ imazaquin < imazethapyr though imazaquin exhibited the highest affinity for soil humic acids. An hypothesis for this behaviour could be that the big and rigid quinoline moiety of the imazaquin molecule does not allow it to reach the adsorption sites of natural soils.

ISSN:0360-1234    

DOI:10.1080/03601239809373162

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The translocation and metabolism of oxamyl and carbofuran were investigated in tomato plants under plastic houses conditions. The producing plants were treated with 20 kg/ Feddan of the 10% granules of either oxamyl or carbofuran. Data explained that both compounds transferred from the roots of tomato plants to their fruits. The concentrations of oxamyl reached 33.4 ppb in tomato fruits after one day following application. This amount increased with time to reach 123.5 ppb after 10 days and at the end of experiment (21 days) declined to be 51.1 ppb. On the other hand, The absorbed amounts of carbofuran reached 312.9 ppb in tomato fruits after one day following treatment. This value increased with time and after 10 days reached at 1003 ppb. At the end of experiment (21 days ) carbofuran amount declined to 130.1 ppb in tomato fruits. The average recoveries of oxamyl and carbofuran from tomato fruits at various spiking levels were 82.6 and 80.2 %, respectively. Oxamyl was metabolized to oximino oxamyl. The amount of this metabolite reached 569.5 ppb in tomato fruits after one day and then heightened to 609.9 ppb after 3 day. Oximino oxamyl amount dropped with time to rerach 184.8 ppb after 10 days and then the amount increased again to arrive 300.1 ppb at the end of experiment (21 days). On the other side, carbofuran was slightly metabolized to 3‐hydroxycarbofuran and 3‐ketocarbofuran phenol. The levels of 3‐hydroxycarbofuran was greater than 3‐ketocarbofuran phenol at all times following application. The results indicated that the translocation and persistence of carbofuran was greater than oxamyl in tomato plants.

ISSN:0360-1234    

DOI:10.1080/03601239809373163

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The herbicide residue levels in leaves ofErythroxylum cocavar.cocaLam. plants treated with soil applications of tebuthiuron and hexazinone at 3.36 and 6.72 kg a.i. ha‐1were determined in order to estimate the potential for human exposure to these residues from consuming the leaves or cocaine produced from them. Field‐grown plants were treated with a commercial formulation of tebuthiuron or hexazinone and leaves were harvested at the first indication of herbicide injury (i.e. chlorosis and/or necrosis) and at the onset of leaf abscission. Herbicide residues were detected by HPLC in leaf samples from both harvests of all plants treated with tebuthiuron or hexazinone. At 3.36 kg ha‐1, herbicide residues in the leaves were less than 2 μg g‐1dry wt. for both harvests of both experiments. The highest residue levels detected were 5.90 μg g‐1dry wt. for tebuthiuron and 7.17 μg g‐1dry wt. for hexazinone in leaves from plants treated with the herbicide at the rate of 6.72 kg ha‐1and harvested at the onset of leaf drop. Based on published toxicity data and estimates of leaf consumption, the herbicide residues in leaves ofE. cocavar.cocaplants treated with tebuthiuron or hexazinone at twice the recommended control rates or less would have a negligible contribution to the health risks of individuals who chew coca leaves. Furthermore, based on the most conservative estimates of cocaine yield and herbicide carry over, death by cocaine overdose would occur long before the NOEL for either herbicide was reached.

ISSN:0360-1234    

DOI:10.1080/03601239809373164

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Toxicity, anticholinesterase properties, elimination and metabolism of carbofuran applied to the larvae of fruit stalk borer,Oryctes eleganswere investigated. Larvae given 10 or 20 ppm of carbofuran did not show any observable signs of acute toxicity. The LC50 values were 82, 62, and 48 ppm following 24, 48, and 72 hrs, respectively. The activity of brain cholinesterase of the treated larvae at 10 ppm level initially decreased during the first three hrs (63.3%), and then the enzyme recovered at the end of the experiment (72 hrs).

ISSN:0360-1234    

DOI:10.1080/03601239809373165

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The effects of well bore volume removal (Vn) on the concentration of alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxy methyl) acetamide] and prometon (6‐methoxy‐N,N'‐bis(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] in ground water obtained from three monitoring wells installed in the Coastal Plain region of North Carolina was investigated. Seasonal effects were also investigated by conducting the exercise in February and May. In the majority of cases, the lowest pesticide concentrations occurred in the initial well bore volume (V1= stagnant water). Removal of additional well bore volumes (V2to V10) from two of the wells resulted in pesticide concentrations that did not vary substantially. This indicates that a representative aquifer sample was obtainable, in most cases from these wells, after removal of the initial well bore volume. In contrast, a third well required the purging of two well bore volumes before a stable alachlor concentration was achieved. Seasonal effects of bore volume removal vs. pesticide concentrations for the three wells were not significant(P >0.05). It was concluded that a protocol for improved accuracy in pesticide analyses of ground water can be obtained by establishing a pesticide concentration‐purging (well bore volume) relationship for each well.

ISSN:0360-1234    

DOI:10.1080/03601239809373166

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A pot experiment using calcareous soil was conducted in a growth chamber to examine the effects of olive oil wastewater applications on Ca fractions in the plant and on exchangeable Ca in soil after plant growth. The experimental treatments consisted of two rates of olive oil wastewater, two mineral fertilizer treatments including K, which supplied K in amounts equivalent to the K supplied by the olive oil wastewater treatments, a mineral fertilizer without K treatment (F), and a control. The pots were sown with ryegrass which was harvested 3 times at monthly intervals. The high rate of olive oil wastewater resulted in a prolonged increase in dry matter production. It also resulted in a reduction in the concentrations of soluble Ca, bound Ca, inorganic insoluble Ca and organic insoluble Ca in the plant shoots relative to the control and the F treatment. The low rate of olive oil wastewater produced similar but less marked effects, with decreases being observed in the soluble Ca and bound Ca fractions. After 3 months of plant growth, soil exchangeable Ca was higher in the control and F treatment soils than in the soils receiving olive oil wastewater or K fertilizer. At this time, there were no significant differences in exchangeable Ca between the soils receiving olive oil wastewater and those treated with K fertilizer.

ISSN:0360-1234    

DOI:10.1080/03601239809373167

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:0360-1234    

DOI:10.1080/03601239809373159

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor