Inge S. Fomsgaard

Comparison and evaluation of eight pesticide environmental risk indicators developed in Europe and recommendations for future use

Original article can be found at: http://www.sciencedirect.com/science/journal/01678809 Copyright Elsevier B.V. [Full text of this article is not available in the UHRA]

Fate and availability of glyphosate and AMPA in agricultural soil

The fate of glyphosate and its degradation product aminomethylphosphonic acid (AMPA) was studied in soil. Labeled glyphosate was used to be able to distinguish the measured quantities of glyphosate and AMPA from the background values since the soil was sampled in a field where glyphosate had been used formerly. After addition of labeled glyphosate, the disappearance of glyphosate and the formation and disappearance of AMPA were monitored. The resulting curves were fitted according to a new EU guideline. The best fit of the glyphosate degradation data was obtained using a first-order multi compartment (FOMC) model. DT50 values of 9 days (glyphosate) and 32 days (AMPA) indicated relatively rapid degradation. After an aging period of 6 months, the leaching risk of each residue was determined by treating the soil with pure water or a phosphate solution (pH 6), to simulate rain over a non-fertilized or fertilized field, respectively. Significantly larger (p < 0.05) amounts of aged glyphosate and AMPA were extracted from the soil when phosphate solution was used as an extraction agent, compared with pure water. This indicates that the risk of leaching of aged glyphosate and AMPA residues from soil is greater in fertilized soil. The blank soil, to which 252 g glyphosate/ha was applied 21 months before this study, contained 0.81 ng glyphosate/g dry soil and 10.46 ng AMPA/g dry soil at the start of the study. Blank soil samples were used as controls without glyphosate addition. After incubation of the blank soil samples for 6 months, a significantly larger amount of AMPA was extracted from the soil treated with phosphate solution than from that treated with pure water. To determine the degree of uptake of aged glyphosate residues by crops growing in the soil, 14C-labeled glyphosate was applied to soil 6.5 months prior to sowing rape and barley seeds. After 41 days, 0.006 ± 0.002% and 0.005 ± 0.001% of the applied radioactivity was measured in rape and barley, respectively.

Degradation of Pesticides in Subsurface Soils, Unsaturated Zone—a Review Of Methods and Results

Abstract Methods and results from degradation studies in subsoils, unsaturated zone, were reviewed for mecoprop, 2,4-D, atrazine, alachlor, aldicarb, carbofuran, linuron, oxamyl, methomyl, MCPA, dichlorprop, monochlorprop, dichlorphenol, TCA, parathion, metribuzin, metolachlor and fenamiphos. Most of the investigations were laboratory studies where small soil samples were sieved and pesticides were added in concentrations from 0.5-5 μg.g−1. A few of the studies mentioned the importance of working with undisturbed samples; another few studies used isotope-labelled pesticides which made it possible to work with concentrations as low as 0.02 μg.g−1. Subsoil samples were characterized according to factors as microbial activity, soil temperature, water content, oxygen content, concentration of pesticide, pretreatment of the soil and soil type, factors considered to have influence on degradation of pesticides. Chemical hydrolysis was considered to be the most dominant pathway in the degradation of aldicarb in s...

Flavonoids in roots of white clover: interaction of arbuscular mycorrhizal fungi and a pathogenic fungus

The effects of two arbuscular mycorrhizal fungi (AMF) (Glomus mosseae and G. claroideum) and a pathogenic fungus (Pythium ultimum) on the production of eight flavonoids in roots of two white clover (Trifolium repens L.) cultivars were evaluated. Quantification of AM and pathogenic fungi in the roots showed that the AM symbiosis significantly reduced P. ultimum biomass and in some cases prevented infection. The flavonoid productions in clover roots varied depending on the presence of beneficial and/or pathogenic fungi, fungal isolate or plant cultivar. Only plants colonized with G. claroideum showed detectable concentrations of either coumestrol or kaempferol (cultivar-dependant). In addition, inoculation with G. claroideum resulted in significantly higher concentrations of coumestrol in cv. Sonja and medicarpin in cv. Milo. A low production of coumestrol and kaempferol in mycorrhizal plants may be G. mosseae-specific. Only the concentrations of formononetin and daidzein increased in clover roots in response to infection with P. ultimum. These flavonoids are supposedly stress metabolites, synthesized or produced from glycosides in response to pathogen infection. However, the presence of one or both AMF significantly lowered the formononetin and daidzein concentrations, and overruled the inductive effect of P. ultimum. Therefore the antagonistic action of AM against the pathogen must take place through another mechanism.

Transformation kinetics of 6-methoxybenzoxazolin-2-one in soil

Wheat (Triticum aestivum L.) and other cereals produce allelochemicals as natural defense compounds against weeds, fungi, insects and soil-borne diseases. The main benzoxazinoid allelochemical of wheat is 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), bound as β-glucoside and released upon plant injury. When leached from wheat to soil, DIMBOA is microbially transformed to 6-methoxy-benzoxazolin-2-one (MBOA). Exploiting benzoxazinoids and their degradation products as substitutes for synthetic pesticides depends on knowledge of transformation pathways and kinetics. In an MBOA degradation experiment at a concentration of 2400 nmol g–1 soil, the previously identified transformation products 2-amino-7-methoxy-phenoxazin-3-one (AMPO) and 2-acetylamino-7-methoxy-phenoxazin-3-one (AAMPO) were quantified. Three different kinetic models were applied to MBOA transformation kinetics; single first-order (SFO), first-order multi-compartment, and double first-order in parallel. SFO proved to be adequate and was subsequently applied to the transformations of MBOA, AMPO and AAMPO. Degradation endpoints, expressed as degradation time (DT), were calculated for MBOA, AMPO and AAMPO to test whether the maximum values for synthetic pesticides set by the European Commission and the Danish Environmental Protection Agency were exceeded. DT50 values for MBOA and AMPO were 5.4 d and 321.5 d, respectively, and DT90 values were 18.1 d and 1068 d, respectively. The DT50 value for AMPO exceeded the maximum value. The persistence, concentrations and toxicity of metabolites such as AMPO should be considered when breeding cereal crops with increased levels of benzoxazinoids.

Biologically active secondary metabolites in white clover (Trifolium repens L.) – a review focusing on contents in the plant, plant–pest interactions and transformation

Summary.To exploit biologically active compounds from white clover (Trifolium repens L.) for suppressing weeds and soil-borne diseases, either as isolated products (biopesticides) or through cultivars with enhanced production of these compounds, the biologically active compounds must be identified, plant content measured, and their fate in soil known. The present review summarizes the published knowledge needed for such exploitation; providing essential information on structure and concentration of flavonols, flavones, condensed tannins, isoflavones, isoflavanones, pterocarpans, coumestans, cyanogenic glucosides, and saponins in healthy and stressed white clover plants. Various stresses and particular cultivars affect the concentrations of several of the compounds. Information on biological effects and the degradation/transformation of these compounds in plants or by microorganisms is available. There is no information on the degradation pathway in soil, the mechanisms of exudation and leaching of compounds from plants, and soil sorption properties of the compounds. The clover soil fatigue problem is increasing in grasslands and causes problems especially in organic farming. Research efforts focused on biological elements of clover soil fatigue have not explained it, and the influence of secondary metabolites has not been investigated. There are few investigations into the interaction between beneficial fungi/fungal-diseases and the occurrence of biologically active secondary metabolites in white clover plants. Such studies are critical to better understand beneficial fungi and pathogens.

Quantification of neonicotinoid insecticide residues in soils from cocoa plantations using a QuEChERS extraction procedure and LC-MS/MS.

The use of neonicotinoids as an insecticide group in Ghana has been quite significant particularly in cocoa production. The high usage has been mainly as a result of a government policy of free insecticide spraying on cocoa farms, in an effort to curb declining yields caused by pests and diseases and to prevent the use of unapproved or banned insecticides on cocoa farms. However the scale of cocoa farming, the frequency and intensity of usage coupled with the mode of application may result in large physical volumes of insecticides in the environment. This makes the knowledge of the concentration and fate of neonicotinoids in the environment extremely important. The present study was aimed at assessing the levels of five major neonicotinoids in soils from cocoa farmlands in Ghana. Extraction and cleanup of analytes were performed by use of a method based on the original QuEChERS procedure after optimizing salts, sorbents and instrumental conditions. Analyte extraction with NaCl and MgSO4 in acidified acetonitrile followed by cleanup with primary secondary amine (PSA) presented the optimum conditions for extraction. Quantification was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). Validation of the procedure showed average recoveries ranging from 72.0 to 104.8% for all analytes at all fortification levels with relative standard deviation (RSD) ≤ 15.0. Limits of quantitation were <10 μg kg(-1) for all neonicotinoids studied. The results obtained from the analysis of 52 samples from cocoa farms revealed imidacloprid as the predominant neonicotinoid with concentrations ranging from 4.3 to 251.4 μg kg(-1) in >50% of samples analyzed.

Modelling the mineralization kinetics for low concentrations of pesticides in surface and subsurface soil

Abstract A number of mathematical models were fitted to mineralization results of low concentrations (004–0.08 μg·g−1) of mecoprop, bentazon and ethylene thiourea (ETU) in surface (ploughed layer) and subsurface soil in different soil types and at different temperatures. It was shown that surface soil kinetics generally could be described with models not including growth of microorganisms and subsurface soil kinetics could best be described with models taking the growth of microorganisms in account. We recommend the use of such kinetic models when pesticide fate in soil is to be predicted.

Comparison of the levels of bioactive benzoxazinoids in different wheat and rye fractions and the transformation of these compounds in homemade foods

Benzoxazinoids are important phytochemicals found in wheat and rye that are associated with plant resistance against pathogens, and recent studies have emphasized the potential health-promoting role of these compounds i.e. anti-cancer, anti-allergy and anti-inflammation. Accordingly, an understanding of their distribution in seeds and the effect of different processing techniques on their transformation will be helpful in identifying the mechanisms of their production and distribution and will support the on-going efforts to utilize these compounds in health-promoting food products. The analysis of seed fractions obtained from the milling of wheat and rye showed significantly higher concentrations of these bioactive compounds in the germ than in the other fractions, i.e. the bran and endosperm. Di-hexoses of 2,4-dihydroxy-1, 4-benzoxazin-3-one (DIBOA-glc-hexose) and 2-hydroxy-1, 4-benzoxazin-3-one (HBOA-glc-hexose) were the predominant compounds found in the different wheat and rye seed fractions followed by DIBOA-glc and DIBOA. The soaking and boiling of three rye-based breakfast cereals resulted in considerable changes in the benzoxazinoid contents. The soaking of pearled rye promoted the conversion of DIBOA-glc-hexose into DIBOA-glc. When these cereals were boiled, the increase in the DIBOA-glc content was much lower than that observed for soaking. For rye flakes, the pattern of these benzoxazinoids was different from that in pearled rye seeds. A considerable amount of the benzoxazinoids was also leached into the water during soaking or boiling. This study contributes to the understanding of the underlying processes involved in the biochemical changes of benzoxazinoids and will be the basis for future studies on other food-processing techniques.

Benzoxazinoids: Cereal phytochemicals with putative therapeutic and health-protecting properties.

Benzoxazinoids (BXs) are a group of natural chemical compounds with putative pharmacological and health-protecting properties. BXs were formerly identified in and isolated from selected dicot medicinal plants and young cereal plants. Recently, BXs were found to be present in mature cereal grains and bakery products, such that knowledge about the pharmacological properties of BXs, which until now have unknowingly been consumed through the daily bread and breakfast cereals, has come into new focus. This review discusses published results from in vitro studies and a few human and animal model studies on the health effects and pharmacological responses of various BX compounds. Many of these studies have reported antimicrobial, anticancer, reproductive system stimulatory, central nervous system stimulatory, immunoregulatory, and appetite- and weight-reducing effects of BXs and/or BX derivatives. The health benefits of wholegrain intake may be associated with the solitary and/or overlapping biological effects of fibers, lignans, phenolic acids, alkylresorcinols, BXs, and other bioactive compounds. In the context of BXs as dietary ingredients, further comprehensive investigations are required to understand their biological functions, to elucidate the underlying mechanisms, to explore their potential contribution on the health effects associated with wholegrain consumption, and to examine their potential as functional food ingredients.