Residues of five pesticides in field‐treated alfalfa seeds and alfalfa sprouts

Abstract

Residues of five different pesticides applied to alfalfa seed crops were determined in the harvested seeds and in sprouts grown from these seeds. Although seeds are usually used for future production of alfalfa plants, some of these seeds may be sprouted for human food consumption. The pesticides studied — aldicarb (Temik®), chlorothalonil (Bravo®), chlorpyrifos (Lorsban®), methamidophos (Monitor®) and propargite (Comite®) — were applied at a normal usage rate and at two to three times that rate. Residues on the seeds and sprouts, if any, were insignificant at rates of application.     

A laboratory study of the persistence of carbofuran and its 3‐hydroxy‐ and 3 keto‐metabolites in sterile and natural mineral and organic soils

Abstract

In a laboratory study, the persistence of carbofuran and its 3‐hydroxy‐ and 3‐keto‐metabolites was examined separately over 16 wk in sterile and natural organic (muck) and mineral (loam) soils. Carbofuran was relatively persistent in sterile soils; at 8 wk 77% remained in the sterile muck and about 50% remained in the sterile loam. In the natural muck 25% of initial carbofuran remained at 8 wk whereas in the natural loam carbofuran had completely disappeared by that time. The 3‐ketocarbofuran was very short‐lived even in the sterile muck where only 50% remained at 1 wk. The 3‐hydroxycarbofuran degraded appreciably on zero day in the natural soils (with conversion to 3‐ketocarbofuran) and about 90% had disappeared in 1 wk. A more detailed study of the persistence of 3‐hydroxycarbofuran in the natural soils showed complete disappearance in 2 days in loam and in 3 days in muck. The 3‐ketocarbofuran produced from the 3‐hydroxy‐carbofuran reached a maximum concentration in 1 day and then disappeared within 4 days in loam and about 1 wk in muck.     

Accelerated degradation of carbofuran in standing water from carbofuran‐retreated Azolla plots

Abstract

Carbofuran (2, 3‐dihydro‐2, 2‐dimethyl‐7‐benzofuranyl N‐methylcarbamate) was mixed with standing water from six flooded Azolla (a fern harboring a nitrogen fixing alga, Anabaena azollae) plots that had been regularly treated with carbofuran before. The insecticide completely disappeared in 5 to 10 days when mixed with water from three of the six plots. The enrichment culture, prepared by further additions of carbofuran to the standing water from an Azolla plot, degraded bendiocarb (2, 2‐dimethyl‐l, 3‐benzidioxol‐4‐yl‐N‐methylcarbamate), carbofuran and carbosulfan [2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl (di‐n‐butyl‐aoinosulfenyl) methyl‐carbamate ] in that order. Enrichment culture, upon sterilization by autoclavlng, lost its ability to degrade carbofuran. Evidently, accelerated degradation of carbofuran in standing water from retreated Azolla plots was mediated by microorganisms.     

Sorption–desorption of indaziflam and its three metabolites in sandy soils

Indaziflam is a relatively new herbicide for which sorption–desorption information is lacking, and nothing is available on its metabolites. Information is needed on the multiple soil and pesticide characteristics known to influence these processes. For four soils, the order of sorption was indaziflam (N-[1R,2S)-2,3-dihydro-2,6-dimethyl-1H-inden-1-yl]-6-[(1R)-1-fluoroethyl]-1,3,5-triazine-2,4-diamine) (sandy clay loam: K_f = 5.9, 1/n_f = 0.7, K_foc = 447; sandy loam: K_f = 3.9, 1/n_f = 0.9, K_foc = 276) > triazine indanone metabolite (N-[(1R,2S)-2,3-dihydro-2,6-dimethyl-3-oxo-1H-inden-1-yl]-6-[(1R)-1-fluoroethyl]-1,3,5-triazine-2,4-diamine) (sandy clay loam: K_f = 2.1, 1/n_f = 0.8, K_foc = 177; sandy loam: K_f = 1.7, 1/n_f = 0.9, K_foc = 118) > fluoroethyldiaminotriazine metabolite (6-[(1R-1-Fluoroethyl]-1,3,5-triazine-2,4-diamine) (sandy clay loam: K_f = 0.3, 1/n_f = 0.9, K_foc = 28; sandy loam: K_f = 0.3, 1/n_f = 0.9, K_foc = 22) = indaziflam carboxylic acid metabolite (2S,3R)-3-[[4-amino-6-[(1R)-1-fluoroethyl]-1,3,5-triazin-2-yl]amino]-2,3-dihydro-2-methyl-1H-indene-5-carboxylic acid) (sandy clay loam: K_f = 0.3, 1/n_f = 0.9, K_foc = 22; sandy loam: K_f = 0.5, 1/n_f = 0.8, K_foc = 32). The metabolites being more polar than the parent compound showed lower sorption. Desorption was hysteretic for indaziflam and triazine indanone metabolite, but not for the other two metabolites. Unsaturated transient flow K_d's were lower than batch K_d's for indaziflam, but similar for fluoroethyldiaminotriazine metabolite. Batch K_d's would overpredict potential offsite transport if desorption hysteresis is not taken into account.     

Persistence of metsulfuron‐methyl in two soils

Abstract

The persistence of metsulfuron‐methyl in sandy loam and clay soil incubated at different temperatures and moistures contents was investigated under laboratory conditions using longbean (Vigna sesquipedalis L.) as bioassay species. A significant degradation of metsulfuron‐methyl was observed in non‐autoclaved soil rather than the autoclaved soil sample. At higher temperature, the degradation rate in non‐autoclaved soil improved with increasing soil moisture content. In non‐autoclaved sandy loam and clay soil, the half‐life was reduced from 9.0 to 5.7 and from 11.2 to 4.6 days, respectively when moisture level of sandy loam increased from 20 to 80% field capacity at 35°C. In the autoclaved soil, herbicide residue seems to have been broken down by non‐biological process. The rate of dissipation was slightly increased after the second application of the herbicide to non‐autoclaved soils but not in autoclaved soil, indicating the importance of microorganisms in the breakdown process.     

Solid‐phase extraction and GC analyses of select agricultural pesticides and metabolites in stream water

Abstract

The occurrence of agricultural pesticides in surface waters around the USA has created a concern over the status of safe drinking water. Solid‐phase extraction (SPE) or liquid‐liquid extraction (LLE) is usually employed to concentrate trace levels of pesticides in water samples to concentrations that are measurable with advanced chromatographic instruments. We describe here a SPE and capillary gas chromatographic (GC) procedure to extract and concentrate trace levels of select agricultural pesticides and metabolites from stream water. Our SPE and GC method provides high sensitivity, with recoveries between 85% to 95%, and high reproducibility for 9 of the pesticides studied. The described method provided marginal recoveries of 19 and 60% for the atrazine metabolites.     

Degradation of chlorpyrifos and its hydrolysis product, 3,5,6‐trichloro‐2‐pyridinol,in soil

Abstract

The degradation of ¹⁴C‐chlorpyrifos and its hydrolysis product, 3,5,6‐trichloro‐2‐pyridinol (TCP), was investigated in soil in laboratory experiments. Between 12 and 57% of the applied chlorpyrifos persisted in a variety of agricultural soils after a 4‐week incubation. Concentrations of TCP present in these soils ranged from 1 to 34% of the applied dose. Two patterns of persistence were observed. In some soils, significant quantities of TCP and soil‐bound residues were produced, but little ¹⁴CO₂. In other soils, neither TCP nor soil‐bound residues accumulated, but large quantities of ¹⁴CO₂ were evolved. Direct treatment of fresh samples of each of these soils with ¹⁴C‐TCP resulted in rapid mineralization of TCP to ¹⁴CO₂ only in those soils in which TCP had not accumulated after chlorpyrifos treatment. The rapid mineralization of TCP in these soils was microbially mediated, but populations of soil microorganisms capable of using TCP as a sole carbon‐energy source were not detected.     

Differential enhanced degradation of cis‐ and trans‐1,3‐D in soil with a history of repeated field applications of 1,3‐D

Abstract

The fumigant 1,3‐dichloropropene (1,3‐D) is considered to be a potential alternative to methyl bromide. The degradation rates of cis‐ and trans‐l,3‐D in soil from a treated site during three successive annual applications of 1,3‐D progressively increased with an increase in the number of annual applications. The enhancement was greater for trans‐l,3‐D degradation than cis‐l,3‐D. In untreated soil, the degradation rates of the two isomers were similar. The enhancement lasted slightly longer than 2 years after annual field application of 1,3‐D had ceased. A single field reapplication of 1,3‐D to the treated site that had not been treated for 2 years resulted in resumed differential enhanced degradation of cis‐ and trans‐l,3‐D. Microorganisms were responsible for the enhanced degradation.     

Metabolism of 14C‐carbaryl and 14C‐1‐naphthol in moist and flooded soils

Abstract

The metabolism of ¹⁴C‐carbaryl and ¹⁴C‐1‐naphthol in moist and flooded soils was studied in a continuous flow‐through system over a period of 28 days permitting ¹⁴C‐mass balance. The percent distribution of radiocarbon in organic volatiles, carbon dioxide, extractable and non‐extractable (bound) fractions of soils were determined. Organic volatiles could not be detected in both carbaryl and 1‐naphthol treated soils. More of ¹⁴CO₂ (25.6%) was evolved from moist than flooded soil (15.1%) treated with carbaryl. However, the mineralization of ¹⁴C‐1‐naphthol was negligible. The extractable radiocarbon was more in flooded soil (28.9%) than moist soil (5.5%) from carbaryl treatment. Less than one percent was present as parent compound, whereas carbaryl was mainly metabolized to 5‐hydroxy carbaryl in moist soil and to 4‐ and 5‐hydroxy carbaryl in flooded soil. The extractable radiocarbon amounted to 18.2 and 24.3% in moist and flooded soils respectively and the parent compound was less than one percent with 1‐naphthol treatment. Most of the radiocarbon was found as soil bound residues; the formation being more with 1‐naphthol than carbaryl. Humin fraction of the soil organic matter contributed most to soil bound residues of both carbaryl and 1‐naphthol.     

Determination of selected pharmaceuticals and caffeine in sewage and seawater from Tromsø/Norway with emphasis on ibuprofen and its metabolites

Selected pharmaceuticals, among them analgesics, ss-blockers and anti-depressants as well as caffeine, the anti-bacterial triclosan and the insect repellent N,N-diethyl-3-toluamide (DEET) were determined in different sewage samples (sewage treatment plants, hospital effluents) from Troms?/Norway and in seawater from Troms?-Sound, into which the sewage is discharged. While caffeine, triclosan, ibuprofen and its major metabolites hydroxy- and carboxy-ibuprofen were present in all sewage samples, additional pharmaceuticals were observed in sewage containing hospital effluents. Concentrations were in the range of 20-293 microg/l (caffeine), 0.2-2.4 microg/l (triclosan) and 0.1-20 microg/l (sum ibuprofen + metabolites). In seawater, only caffeine (7-87 ng/l), DEET (0.4-13 ng/l) and ibuprofen + metabolites (sum concentration < LOQ-7.7 ng/l) were detected. Ibuprofen and its metabolites hydroxy- and carboxy-ibuprofen were quantified individually by use of the respective reference compounds. Relative amounts of the three compounds were determined in different types of water showing characteristic patterns, with hydroxy-ibuprofen being the major component in sewage whereas carboxy-ibuprofen was dominant in seawater samples. The patterns which were compared to those observed in similar samples from Germany indicated different transformation behaviour under limnic and marine conditions.     

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).     

Residues of 2,4‐D in air samples from Saskatchewan: 1966–1975

Abstract

Residues of 2,4‐D (2,4‐dichlorophenoxyacetic acid) in air samples from several sampling sites in central and southern Saskatchewan during the spraying seasons in the 1966–68 and 1970–75 periods were determined by gas‐liquid Chromatographic techniques. Initially, individual esters of 2,4‐D were characterized by retention times and confirmed further by co‐injection and dual column procedures. Since 1973, however, only total 2,4‐D acid levels in air samples have been determined after esterification to the methyl ester and confirmed by gc/ms techniques whenever possible.

Up to 50% of the daily samples collected during the spraying season at any of the locations and during any given year contained 2,4‐D, with butyl esters being found most frequently. The daily 24‐hr mean atmospheric concentrations of 2,4‐D ranged from 0.01 to 1.22 μg/m³, 0.01 to 13.50 μg/m³, and 0.05 to 0.59 μg/m for the iso‐propyl, mixed butyl and iso‐octyl esters, respectively. Even when the samples were analysed for the total 2,4‐D content, i.e. from 1973 onwards, the maximum level of the total acid reached only 23.14 μg/m. In any given year and at any of the sampling sites, about 30% of the samples contained less than 0.01 μg/m³ of 2,4‐D. In another 40% of the samples, the levels of 2,4‐D ranged from 0.01 to 0.099 yg/m. Only about 30% of the samples contained 2,4‐D concentrations higher than 0.1 μg/m³, with only 10% or less exceeding 1 μg/m³.

None of the samples, obtained with the high volume particu‐late sampler, showed any detectable levels of 2,4‐D, indicating little or no transport of 2,4‐D adsorbed on dust particles or as crystals of amine salts.     

Fate and residues of 14C‐chloramphenicol in laying chickens 1

Abstract

Studies were conducted to determine the metabolic fate of chloramphenicol (CAP) in White Leghorn using the ^l4C‐labelled compound. In one experiment birds were administered orally via intra‐crop, a single dose of 100 mg (equivalent to 66 mg kg^‐1 body weight) of CAP containing 14 μCi ¹⁴C‐CAP, and its absorption, elimination and distribution in plasma were recorded. Orally dosed ¹⁴C‐compound was rapidly absorbed, efficiently distributed in plasma and eliminated in excreta (>70% in 5 hr). After 5 h, CAP equivalent residues in tissues were lower than 15 μg g^‐1 for this treatment. In a second experiment birds were given intra‐crop dose of either 0.5 or 5 mg of CAP (each dose contained 2.5 μCi ¹⁴C‐CAP) daily for five consecutive days followed by a seven day withdrawal period and elimination of ¹⁴C in excreta and eggs was monitored. More than 95% of the administered ¹⁴C was eliminated within the first 24 h after dosing. Radiocarbon (¹⁴C) was deposited preferentially in yolks compared to albumen or other tissues. Residues declined when feeding was stopped. Various metabolites were isolated and identified by a combination of TLC, LC, and LC‐MS. The main metabolic route of CAP in laying hens appears to be the glucuronidation. Cleavage of the dichloroacetate moiety was only a minor route.     

The effects of triclopyr on 2,4‐D mineralization in two soils

Abstract

The effects of the herbicide triclopyr (3,5,6‐trichloro‐2‐pyridinyloxyacetic acid) on the mineralization of 2,4‐D (2,4‐dichlorophenoyxacetic acid) in two soils which differed in their histories of prior exposure to the two herbicides were investigated. The relative effects of triclopyr on 2,4‐D mineralization and most probable numbers of 2,4‐D degraders were dependent upon the soil. Triclopyr was shown to increase 2,4‐D mineralization rates in a soil which had been exposed to both 2,4‐D and triclopyr, but decreased the mineralization rate of 2,4‐D and inhibited the increase of most probable numbers of 2,4‐D degraders in a soil that had not been directly exposed to either herbicide.     

Evaluation of C18 solid‐phase extraction cartridges for the isolation of select pesticides and metabolites

Abstract

Nine different C₁₈ solid‐phase extraction (SPE) cartridges were evaluated for their efficiency at extracting nine pesticides and two s‐triazine metabolites from spiked deionized water samples. The SPE cartridges were found to contain nitrogen (N) and/or phosphorus (P) contaminants and varied in their extraction efficiency for certain pesticides and metabolites. Four of the nine SPE cartridges gave acceptable (70 to 120%) pesticide and metabolite recovery percentages, while five cartridges had marginal (50 to 70%) to poor (< 50%) recoveries. Statistical analyses showed that the poor to marginal recoveries found for three compounds could not be explained by considering several indigenous chemical and physical traits of the cartridge. It is suggested that proper SPE cartridge selection for pesticide recovery should be evaluated using several different cartridges.     

Stability of cocaine and its metabolites in municipal wastewater – the case for using metabolite consolidation to monitor cocaine utilization

Transformations of cocaine and eleven of its metabolites were investigated in untreated municipal sewage at pH?≈?7 and 9, 23, and 31 °C. Results indicated that hydrolysis—possibly bacterially mediated—was the principal transformation pathway. Residues possessing alkyl esters were particularly susceptible to hydrolysis, with pseudo-first-order rate constants varying from 0.54 to 1.7 day^?1 at 23 °C. Metabolites lacking esters or possessing only a benzoyl ester appeared stable. Residues lacking alkyl esters did accumulate through hydrolysis of precursors, however. As noted previously, this may positively bias cocaine utilization estimates based on benzoylecgonine alone. Reported variability in metabolic excretion was used in conjunction with transformation data to evaluate different approaches for estimating cocaine loading. Results indicate that estimates derived from measurands that capture all major cocaine metabolites, such as COC_tot (the sum of all measurable metabolites) and EC_hyd (the sum of all metabolites that can be hydrolyzed to ecgonine), may reduce uncertainty arising from variability in metabolite transformation and excretion, possibly to?≈?10 % RSD. This is more than a two-fold reduction relative to estimates derived from benzoylecgonine (>26 % RSD), and roughly equivalent to reported uncertainties from sources that are not metabolite-specific (e.g., sampling frequency, flow variability). They and other composite measurands merit consideration from the sewage epidemiology community, beginning with efforts to evaluate the stability of the total cocaine load under realistic sewer conditions.     

Determination of propineb and its metabolites propylenethiourea and propylenediamine in banana and soil using gas chromatography with flame photometric detection and LC–MS/MS analysis

A sensitive and specific method for the determination of propineb and its metabolites, propylenethiourea (PTU) and propylenediamine (PDA), using gas chromatography with flame photometric detection (GC-FPD) and LC–MS/MS was developed and validated. Propineb and its metabolite residue dynamics in supervised field trials under Good Agricultural Practice (GAP) conditions in banana and soil were studied. Recovery of propineb (as CS₂), PDA and PTU ranged from 75.3 to 115.4% with RSD (n = 5) of 1.3–11.1%. The limit of quantification (LOQ) of CS₂, PDA and PTU ranged from 0.005 to 0.01 mg kg^?1, and the limit of detection (LOD) ranged from 0.0015 to 0.0033 mg kg^?1. Dissipation experiments showed that the half-life of propineb in banana and soil ranged from 4.4 to 13.3 days. PTU was found in banana with a half-life of 31.5–69.3 days, while levels of PDA were less than 0.01 mg kg^?1 in banana and soil. It has been suggested that PTU is the major metabolite of propineb in banana. The method was demonstrated to be reliable and sensitive for the routine monitoring of propineb and its metabolites in banana and soil. It also serves as a reference for the detection and monitoring of dithiocarbamates (DTCs) residues and the evaluation of their metabolic pathway.     

Chemical and biological release of 14C‐bound residues from soil treated with 14C‐p,p'‐DDT

Abstract

¹⁴C‐p,p'‐DDT‐bound residues in soil can be released by treatment with concentrated sulphuric acid at ambient temperatures. Within 6 days, about 70% of the bound residues was released. Bound residues released after 9 months incubation with ¹⁴C‐DDT showed the presence of DDT and DDE only while bound residues released after 18 months, contained in addition 13% DDD.

Release of bound ¹⁴C‐residues also occurs readily following inoculation of the soil‐bound residues with fresh soil or with individual microorganisms. Almost complete release of bound residues was observed after incubation for 45 days. The rate of release was rapid during the first two weeks and decreased thereafter. TLC and HPLC analysis showed that the released residues contained DDE (about 80%) and a smaller amount of DDD. The disappearance of DDT from the released residues may be attributed to its microbiological degradation to DDE and DDD, shortly after its release.     

Transient‐phase and steady‐state kinetics of lipase‐catalyzed ester hydrolysis 1

Abstract

An experimental study has been made of both the steady‐state and the transient‐phase (presteady‐state) kinetics of the hydrolyses of several saturated aliphatic esters of p‐nitrophenol catalyzed by wheat germ lipase. The analysis of the presteady‐state part revealed two transients indicating that lipase‐catalyzed reactions proceed via a two‐intermediate mechanism suggested for other esterases. The possibility of more than one species of the enzyme engaged in catalytic activity is discussed and a reaction mechanism scheme is proposed accordingly.     

Residue levels and dietary risk assessment of fluopimomide,pyraclostrobin and its metabolite BF-500–3 in garlic ecosystems under field conditions

Environmental Science and Pollution Research - To evaluate the residue levels of fluopimomide, pyraclostrobin and its metabolite BF-500–3 in garlic ecosystems, supervised garlic field trials...