Formation and degradation of triademinol after the use of triadimefon in a wheat monoculture]

During two vegetation periods, the behaviour of the triadimefon metabolite, triadimenol, in different plant parts of winter wheat and in soil was investigated. The fungicide Bayleton DF (triadimefon + captafol) was applied at the beginning of earing. Different ratios of triadimenol-A/-B were found in individual plant parts. Triadimenol-A predominated in the two uppermost leaves, and triadimenol-B in the roots and in the soil. No residues of triadimenol were found in grain at harvest time (detection limit 0.01 mg/kg).     

Behavior of captafol residues after prolonged application in a wheat monoculture

In a 4-year study, the behaviour of the residues of the fungicide captafol in different plant parts of winter wheat and in the soil was investigated. The fungicide Bayleton DF (captafol + triadimefon) was applied at the beginning of earing. Captafol residues clearly showed a high dependence on weather conditions in all examined aerial parts of the plant. After a 9-year application of captafol, there was no evidence of an enrichment of residues in the soil. At harvest, captafol residues in grains always were below the maximum residue limits of 0.5 mg/kg established in West Germany.     

Behavior of triadimefon in two Lebanese soils.

The retention and fate of triadimefon fungicide were studied under two environmental conditions. Field studies were conducted on two soils, a sandy loam soil (Fanar) and a clay soil (Raouda). Fanar is a wet coastal area while Raouda is a dry agricultural area of the Bekaa plain located at an elevation of 870 m above sea level. Triadimefon was applied with a jet sprayer at 267 g a.i.ha(-1) and 200 g a.i.ha(-1) at Fanar and Raouda, respectively. Reconstituted soil columns (600 x 30 mm) glasses, were used to study the fungicide movement and metabolism in the two soils. Analyses of triadimefon and its metabolites were carried out using gas chromatography (GC) and high performance liquid chromatography (HPLC). The results indicated a weak reversibility of the adsorbed fraction in the clay soil. Clay is considered an important factor in triadimefon adsorption. Triadimefon mobility in the sandy-loam soil was relatively high in comparison with behavior in the clay soil where about half of the applied fungicide was detected in the upper 25 cm of soil, six days after treatment. Rapid degradation of triadimefon to triadimenol was observed in the two soils. The observed half-life was 8 days in sandy-loam and 13 days in clay soils.     

Fate of 14C‐lindane in a rice‐fish model ecosystem*

Abstract

A model ecosystem has been used to evaluate the impact of ¹⁴C‐lindane on rice‐fish agricultural system. The distribution of ¹⁴C‐residues among the constituents of the model ecosystem was studied over a period of 90 days. The insecticide was found to be readily absorbed by the roots and translocated to all parts of the rice plant. The peak level in the shoots (26 ppm) and roots (105 ppm) of plants was reached to within three weeks. Lindane was concentrated in fish and residues as high as 90 ppm could be detected after 30 days.

The major part of the residues present in the different constituents of the ecosystem could be extracted with hexane and proved to contain soley the parent compound. The data obtained show that lindane possesses a relatively low biodegradability in fish and in rice plant. The insecticide accumulates in fish and rice plant to considerable extent.     

Determination of disulfoton and permethrin residues in an organic soil and their translocation into lettuce,onion and carrot 1

Abstract

The residues of disulfoton and permethrin in an organic soil and in vegetables grown in soil treated with a granular formulation of the pesticides were determined by gas chromatography. The residues were removed from soil or plant samples by successive extractions with acetone and hexane. Permethrin persisted in the soil for the initial 28 days and declined slowly during the rest of the season but disulfoton after persisting for one week at the applied concentration was degraded in the next two weeks. The insecticides did not translocate into the edible parts of the vegetables but were present in the root system of onion and lettuce. Carrot and lettuce yields were not significantly different from those of the controls but onion yields were substantially decreased by the use of per‐methrin.     

Effects of fungicides triadimefon and propiconazole on soil bacterial communities

The impact of fungicides triadimefon and propiconazole on soil bacterial populations from a strawberry field was investigated. Two fungicides were applied to the soil at concentrations of 10 mg/kg or 100 mg/kg with soil water contents 20.2% (fresh soil water content) or 26.0% (field capacity). Changes in bacterial communities were assessed using DNA extraction, polymerase chain reaction (PCR) amplification of the 16S rDNA and denaturing gradient gel electrophoresis (DGGE). High performance liquid chromatography (HPLC) was utilized to detect the residue of fungicides in soils. The results showed that propiconazole was more persistent than triadimefon in soils, and the two soil water contents did not cause significant differences in dissipation rates between the two fungicides. A high concentration of propiconazole could inhibit the existence of soil microbes while one of triadimefon might induce the microbial population in the first stage. From unweighted pair-group method using arithmetic averages (UPGMA) dendrograms, the effect of triadimefon and propiconazole at the two applied concentrations on a soil bacterial community could be long term. After triadimefon was applied for 60 days and propiconazole for 75 days, the compositions of microbial communities were not recovered. From the viewpoint of environmental protection, it was of significant importance to pay more attention not only to the residues of pesticide but also to the change in soil microbial communities.     

Persistence of repeated triadimefon application and its impact on soil microbial functional diversity

The effects of repeated applications of the fungicide triadimefon in agricultural soil on the microbial functional diversity of the soil and on the persistence of the fungicide in the soil were investigated under laboratory conditions. The degradation half-lives of triadimefon at the recommended dosage, simulated by a first-order kinetic model, were 23.90, 22.95, and 21.52 days for the first, second, and third applications, respectively. Throughout this study, no significant inhibition of the Shannon-Wiener index (H′) was observed. However, the Simpson index (1/D) and the McIntosh index (U) were obviously reduced (p ≤ 0.05) during the initial 3 days after the first triadimefon application and thereafter, gradually recovered to or exceeded the level of the control soil. A similar trend in variation but with a faster recovery in the 1/D and U was observed after the second and third triadimefon applications, respectively. Taken together, the above results indicate that the repeated application of triadimefon enhanced the degradation rate of the fungicide and the recovery rate of the soil microbial functional diversity. It is concluded that repeated triadimefon applications in soil have a transient or temporary inhibitory effect on soil microbial communities.     

Degradation of atrazine,metolachlor, and pendimethalin in pesticide‐contaminated soils: Effects of aged residues on soil respiration and plant survival

Abstract

This study was conducted to determine the effects of pesticide mixtures on degradation patterns of parent compounds as well as effects on soil microbial respiration. Bioavailability of residues to sensitive plant species was also determined. Soil for this study was obtained from a pesticide‐contaminated area within an agrochemical dealer site. Degradation patterns were not affected by the presence or absence of other herbicides in this study. Atrazine concentrations were significantly lower at 21 through 160 days aging time compared to day 0 concentrations. Metolachlor and pendimethalin concentrations were not significantly different over time and remained high throughout the study. Microbial respiration was suppressed in treated soils from day 21 to day 160. Soybean and canola were the most successful plant species in the germination and survival tests. Generally, with increased aging of pesticides in soil, germination time decreased. Survival time of plants increased over time for some treatments indicating possible decreased bioavailability of pesticide residues. In some cases, survival time decreased at the longer 160‐day aging period, possibly indicating a change in bioavailability, perhaps as the result of formation of more bioavailable and phytotoxic metabolites. No interactive effects were noted for mixtures of pesticides compared to individually applied pesticides in terms of degradation of the parent compound or on seed germination, plant survival, or microbial respiration.     

Careers in Air Pollution Control

Abstract

The destruction of parts per million (ppm) levels of volatile organic compounds in a dry air stream by high–energy electron–beam irradiation has been investigated in a pilot plant at the University of Tennessee Space Institute, Tullahoma, Tennessee. In a series of experiments, dry air contaminated with various VOCs in the concentration range of 50–1000 ppm were treated in the UTSI pilot plant to determine the extent of destruction at various electronbeam dose levels.

The destruction removal efficiency was determined as a function of the electron beam irradiation dose. The results suggest a charge transfer reaction as the major decomposition mechanism. A theoretical foundation of the process, along with a simple first–generation reaction kinetics model, a summary of the results from the pilot plant flow reactor, and a preliminary cost analysis for a fullscale detoxification plant using currently available electronbeam gun technology are presented in this paper.     

Ammonia volatilization from crop residues and frozen green manure crops

Agricultural systems can lose substantial amounts of nitrogen (N). To protect the environment, the European Union (EU) has adopted several directives that set goals to limit N losses. National Emission Ceilings (NEC) are prescribed in the NEC directive for nitrogen oxides and ammonia. Crop residues may contribute to ammonia volatilization, but sufficient information on their contribution to the national ammonia volatilization is lacking. Experiments were carried out with the aim to assess the ammonia volatilization of crop residues left on the soil surface or incorporated into the soil under the conditions met in practice in the Netherlands during late autumn and winter.Ammonia emission from residues of broccoli, leek, sugar beet, cut grass, fodder radish (fresh and frozen) and yellow mustard (frozen) was studied during two winter seasons using volatilization chambers. Residues were either placed on top of soil or mixed with soil. Mixing residues with soil gave insignificant ammonia volatilization, whereas volatilization was 5–16 percent of the N content of residues when placed on top of soil.Ammonia volatilization started after at least 4 days. Total ammonia volatilization was related to C/N-ratio and N concentration of the plant material. After 37 days, cumulative ammonia volatilization was negligible from plant material with N concentration below 2 percent, and was 10 percent of the N content of plant material with 4 percent N. These observations can be explained by decomposition of plant material by micro-organisms. After an initial built up of the microbial population, NH₄⁺ that is not needed for their own growth is released and can easily emit as NH₃ at the soil surface.The results of the experiments were used to estimate the contribution of crop residues to ammonia volatilization in the Netherlands. Crop residues of arable crops and residues of pasture topping may contribute more than 3 million kg NH₃–N to the national ammonia volatilization of the Netherlands, being more than 3 percent of the national emissions in 2005. This contribution should therefore be considered when focusing on the national ceilings for ammonia emissions.     

Stabilization of Heavy Metal Containing Hazardous Wastes with Byproducts from Advanced Clean Coal Technology Systems

ABSTRACT

The purpose of this investigation was to evaluate the success of residues from advanced Clean Coal Technology (CCT) systems as stabilization agents for heavy metal containing hazardous wastes. In the context examined here, stabilization refers to techniques that reduce the toxicity of a waste by converting the hazardous constituents to a less soluble, mobile, or toxic form.¹ Three advanced CCT byproducts were used: coal waste-fired circulating fluidized bed combustor residue, pressurized fluidized bed combustor residue, and spray drier residue. Seven metal-laden hazardous wastes were treated: three contaminated soils, two air pollution control dusts, wastewater treatment plant sludge, and sandblast waste. Each of the seven hazardous wastes was treated with each of the three CCT byproducts at dosages of 10, 30, and 50% by weight (byproduct:waste). The treatment effectiveness of each mixture was evaluated by the Toxicity Characteristic Leaching Procedure. Of the 63 mixtures evaluated, 21 produced non-hazardous residues. Treatment effectiveness can likely be attributed to mechanisms such as precipitation and encapsulation due to the formation of hydrated calcium silicates and calcium sulfo-alu-minates. Results indicate that these residues have potential beneficial uses to the hazardous waste treatment community, possibly substituting for costly treatment chemicals.     

Control of blueberry thrips,frankliniella vaccinii morgan,with permethrin and effect on yield and residue in fruit

Abstract

Permethrin at 0.4 kg a.i./ha controlled blueberry thrips Frankliniella vaccinii Morgan. There was no plant damage and crop yield was notably increased. Permethrin was extracted from berries with acetone, partitioned in hexane, cleaned‐up on Florisil column and analysed by the electron capture gas chromatography using a 3% OV‐210 column. No permethrin residues were found in the berries. The relative retention times of cis‐, and trans‐permethrins to aldrin were 10.3 and 12.1, respectively. The absence of permethrin from berries was further confirmed by TLC.     

Plant availability of bound anilazine residues in a degraded loess soil

Abstract

The relative biological availability of [benzene ring‐U‐¹⁴C] and Ctriazine‐U‐¹⁴C] anilazine for maize plants was studied in a degraded loess soil in a standardized microecosystem. The total uptake of radiocarbon in the course of the 4‐week experiment was 3.1 and 4 % respectively of the radioactivity applied if anilazine was uniformly mixed into the soil immediately before beginning the experiment. However, if anilazine was subjected to a degradation at 65 % of the maximum water holding capacity of the soil and temperatures varying daily between 16 and 27°C for 100 days before the plant experiment then the uptake was reduced to 0.4 or 0.7 % respectively. The uptake from soil with non‐extractable (bound) anilazine residues was similarly low. The mineralization rate of aged and bound anilazine residues was below 0.1 % of the radioactivity applied. Up to 2/3 of the radioactivity present in the soil after the plant experiment remained in the humic fraction.     

Investigation on the Chemical Structure of Nonextractable Residues of the Fungicide Cyprodinil in Spring Wheat Using 13C-C1-Phenyl-Cyprodinil on 13C-Depleted Plants—An Alternative Approach to Investigate Nonextractable Residues

Abstract

¹³C-labelled cyprodinil was applied on ¹³C-depleted wheat plants with 27-fold field application rate. A control experiment applying same amounts of ¹⁴C-cyprodinil showed that main portions of the residues were detected in the cellulose (15% NER), hemicellulose (28.3% NER), and lignin fraction (23.3% NER). 16.7% were detected in water soluble polymers, 6% in both, pectin and protein fraction, and 4% in the starch containing fraction. Free cyprodinil was detectable by TLC in all fractions except lignin. A direct characterization of the residues in vivo by CP-MAS was not successful. Cell wall fractions were further analysed by liquid state NMR to determine the structure of the mobilized highly polymer/polar residues: Within lignin, where most of the residues were located at field application rate, neither intact cyprodinil nor its metabolites could not be detected. The ¹³C-label introduced was probably incorporated in the polymer as natural lignin monomers and thus are not considered as bound residues according to IUPAC definition.     

Translocation of aged cyclodiene insecticide residues from soil into forage crops and pastures at various growth stages under field conditions

Abstract

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.

Compared to glasshouse studies undertaken previously, residues in crops grown under field conditions were much lower, this apparently reflects the lower soil moisture levels and the reduced rates of translocation.

Heptachlor residues in winter crops were highest in Saia oats > Berseem clover > Haifa clover > Cassia oats > Tetila ryegrass > Schooner barley > Shaftal clover > Hunter river lucerne at the grazing stage. There were no detectable levels in barley and oats at the mature stage. No dieldrin residues were translocated into the various crop species.     

Analysis and fate of acephate and its metabolite,methamidophos, in pepper and cucumber

Abstract

Levels of acephate (Orthene^R) and its principle metabolite, methamidophos, in/on greenhouse‐grown pepper and cucumber fruits and leaves in relation to the applied methamidophos were monitored. Dislodgeable and total residues of acephate and methamidophos were determined by gas‐liquid chromatography equipped with a flame ionization detector (GC‐FID) and were confirmed by nitrogen phosphorus detector (GC‐NPD). The dissipation curves of the residues followed first‐order kinetics (R²> 0.96). Initial residues of acephate on fruits varied between pepper (15.12 ppm) and cucumber (2.16 ppm) . Total residues in fruits and leaves determined at intervals following application revealed the greater persistence of acephate on pepper fruits (half‐life [t_1/2] of 6 d) than on cucumber fruits (t_1/2 was 3.7 d) . T_1/2 values for the applied methamidophos were 4.7 and 5.3 d on pepper and cucumber fruits, respectively. Deacety‐lation of acephate (formation of its metabolite) was detectable 1 d following acephate treatment and reached a maximum of 2.05% of initial acephate residues 3 d after application on pepper fruits. On cucumber fruits, acephate metabolite reached a maximum of 2.12% one wk following application. No acephate residues were detected above the limit of detection of 0.001 ppm in pepper fruits 50 d following acephate application while its metabolite was detectable at that time (detectability limit was 0.0001 ppm).     

Residues behavior of some fungicides applied on two greenhouse tomato varieties different in shape and weight

The degradation of 12 fungicides (azoxystrobin, cymoxanil, cyproconazole, cyprodinil, fenarimol, fludioxonil, iprovalicarb, mepanipyrim, penconazole, pyrimethanil, tolclofos-methyl, triadimenol), commonly used in pest management strategies on Sardinian greenhouse tomato crops was studied. A different residue behaviour was observed between the studied cultivar. On the smaller, a "cherry" type tomato, field data showed an initial residue mostly higher than the "beefsteak" tomato. In any case, except for penconazole, all pesticide residues were below their maximum residue levels (MRLs) reaching the pre-harvest interval (PHI). On both cultivar, triadimenol and cymoxanil residues completely disappeared reaching their PHI, while iprovalicarb, fenarimol, and fludioxonil disappeared in a time of 17 to 24 days. On the contrary, azoxystrobin, cyproconazole, cyprodinil, penconazole, tolclofos-methyl, mepanipyrim, and pyrimethanil showed a long persistence on both tested cultivar and may have residual problems due to an accumulation effect if repeated field treatments will be performed. The first group of molecules according to their rapid degradation could be used in low pesticide-input management in order to obtain tomatoes with low or no detectable residues.     

Fate of parathion in soil under sub‐tropical field conditions

Abstract

Persistence, metabolism and binding of ¹⁴C‐parathion in alkaline sandy loam soil under sub‐tropical conditions of Delhi were studied for 545 days. After 3 days of treatment, ¹⁴C‐residues declined to 41% of the amount applied. The dissipation curve was biphasic; an initial rapid phase (up to 7 days) followed by slow dissipation. The half life of dissipation was only 3.36 days for the first phase and 84 days for the slow phase. The overall half life was 64.5 days. The total residues at zero‐time were 10.65 μg/g dry soil and were almost totally extractable. The extracts consisted of parathion, 4‐aminophenol, 4‐nitrophenol and paraoxon. The bound residues gradually increased and accounted for the total residue at the end of one year (0.7 μg/g).     

Fate of permethrin in model outdoor ponds

Abstract

In 1979 and 1980, outdoor artificial ponds were treated with ¹⁴C‐pennethrin (labelled at either the cyclopropyl or methylene position) at 0.028 kg/ha (15 ug/L). Uptake of permethrin by duckweed and hydrosoil was monitored by direct combustion, TLC‐autoradiography, HPLC, and liquid scintillation counting. Rapid loss of permethrin from the waiter coincided with the detection of five degradation products in the water at concentrations below 2.0 ug/L. The products were cis‐ and trans‐cyclopropyl acid, phenoxybenzoic acid, and phenoxybenzyl alcohol, and an unknown non‐cleaved product of permethrin. Permethrin was readily sorbed by duckweed but was not persistent. Permethrin residues in the hydrosoil, which was the major sink for permethrin added to the ponds, were persistent and were detected at 420 days post‐treatment. Cis‐permethrin was more persistent in the hydrosoil than the trans‐permethrin. The results indicated that permethrin in water was short‐lived at an application rate of 15 ug/L because of the rapid degradation of permethrin in the water and sorption of permethrin by the hydrosoil and vegetation. However, at one year post‐treatment, permethrin residues were still detected in the hydrosoil at 1.0 ug/kg.     

Residues behavior of some fungicides applied on two greenhouse tomato varieties different in shape and weight

The degradation of 12 fungicides (azoxystrobin, cymoxanil, cyproconazole, cyprodinil, fenarimol, fludioxonil, iprovalicarb, mepanipyrim, penconazole, pyrimethanil, tolclofos-methyl, triadimenol), commonly used in pest management strategies on Sardinian greenhouse tomato crops was studied. A different residue behaviour was observed between the studied cultivar. On the smaller, a “cherry” type tomato, field data showed an initial residue mostly higher than the “beefsteak” tomato. In any case, except for penconazole, all pesticide residues were below their maximum residue levels (MRLs) reaching the pre-harvest interval (PHI). On both cultivar, triadimenol and cymoxanil residues completely disappeared reaching their PHI, while iprovalicarb, fenarimol, and fludioxonil disappeared in a time of 17 to 24 days. On the contrary, azoxystrobin, cyproconazole, cyprodinil, penconazole, tolclofos-methyl, mepanipyrim, and pyrimethanil showed a long persistence on both tested cultivar and may have residual problems due to an accumulation effect if repeated field treatments will be performed. The first group of molecules according to their rapid degradation could be used in low pesticide-input management in order to obtain tomatoes with low or no detectable residues.