Effect of four organophosphorus insecticides on microbial activities in soil.
01 Mar 1970-Applied and Environmental Microbiology (American Society for Microbiology)-Vol. 19, Iss: 3, pp 479-484
TL;DR: Oxygen consumption indicated that microbial respiration increased in proportion to the concentration of insecticides, suggesting the possibilities of microbial degradation of the insecticides or their degradation products and of uncoupling oxidative phosphorylation.
Abstract: Laboratory tests were conducted with four organophosphorus insecticides, Bay 37289 (O-ethyl O-2,4,5-trichlorophenyl ethylphosphonothioate), diazinon [O,O-diethyl O-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate], Dursban (O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate), and Zinophos (O,O-diethyl O-2-pyrazinyl phosphorothioate), applied to a sandy loam at rates of 10 and 100 μg/g to determine whether these materials caused any serious effects on microbial activities related to soil fertility. All insecticides showed an effect on fungi and bacteria for the first and second week of incubation, but, subsequently, the populations returned to levels similar to those obtained in the controls. All insecticide applications increased ammonium production, but, in some instances, there appeared to be a slight depression of nitrification. Sulfur oxidation was equal to or better than that obtained with untreated soil in most cases. There was no significant effect on phosphorus mineralization. Oxygen consumption indicated that microbial respiration increased in proportion to the concentration of insecticides, suggesting the possibilities of microbial degradation of the insecticides or their degradation products and of uncoupling oxidative phosphorylation.
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TL;DR: The effects of parathion on the growth of bacteria, fungi, and algae is shown to be dose dependent, with very low concentrations having no effect at all and higher concentrations drastically arresting the multiplication of the microorganisms.
272 citations
TL;DR: Chlorpyrifos effects in aquatic ecosystems are complex because of the diversity of species assemblages and trophic interactions, and functional endpoints are less sensitive than structural parameters of ecosystems (e.g., community metabolism).
Abstract: Chlorpyrifos is a broad-spectrum organophosphorothioate insecticide with a principal mechanism of toxicity by inactivation of acetylcholinesterase at nerve junctions. Unlike certain organochlorine pesticides, chlorpyrifos is relatively nonpersistent (Racke 1993), and its principal degradation products are less toxic than the parent chemical. Species sensitivity varies considerably across kingdom and phyla. In general, aquatic and terrestrial microorganisms and plants are tolerant to chlorpyrifos exposure. Aquatic invertebrates, particularly crustaceans and insect larvae, are sensitive to exposure: LC50s are generally less than 1 microgram/L, and no-observed-effect concentrations may be below 0.1 microgram/L in laboratory studies. Fish appear to be less sensitive, with LC50s generally between 1 and 100 micrograms/L and no-observed effect concentrations of approximately 0.5 microgram/L. In general, saltwater and freshwater organisms exhibit similar sensitivity to chlorpyrifos, considering the extreme phylogenetic and species differences in toxicity. Chlorpyrifos effects in aquatic ecosystems are complex because of the diversity of species assemblages and trophic interactions. In general, functional endpoints (e.g., community metabolism) are less sensitive than structural parameters of ecosystems (e.g., loss of sensitive species). Ecosystem recovery is dependent on the interaction of a variety of factors including treatment timing and application dose, rate of dissipation, species assemblages, trophic structure, and the reproductive capacity and growth rate of susceptible and tolerant populations. Terrestrial species are relatively tolerant of chlorpyrifos exposure, although contact toxicity to sensitive terrestrial invertebrates may occur at concentrations of 0.1 microgram/insect. Amphibians, birds, and mammals show similar sensitivity to orally administered chlorpyrifos, with LD50s ranging from 8 to > 400 mg/kg body weight. Long-term chronic feeding studies in birds and mammals have shown no observed effect concentrations to be greater than 1 mg/kg food. In general, field studies have shown limited or no acute toxicity to amphibians, reptiles, birds, or mammals.
177 citations
TL;DR: The role of microorganisms in S oxidation in atmospheric S-polluted soils is largely overlooked, although it is clear that microbial oxidization of reduced S does occur in ecosystems that receive particulate deposits from pollution sources such as, coking and smokeless fuel plants as discussed by the authors.
Abstract: Publisher Summary This chapter discusses oxidation of sulfur (S) in soils. Soils throughout the world are increasingly recognized as being S deficient, and deficiencies in the element are even appearing in soils in countries where such deficiencies were previously unknown. These deficiencies result mainly from the use of high analysis, low S-containing fertilizers, reduction in the use of elemental S as a fungicide, and increasing effectiveness in SO 2 -pollution abatement programs. Reduced forms of S are often added to soils to overcome these deficiencies in plant-available S, on the assumption that microorganisms oxidize them to plant-available S0 4 2- . The process of S oxidation in soils is derived from laboratory studies, reflecting an almost total absence of field-based investigations. Despite the fact that fertilizer S is likely to be directed toward plant roots, there is a similar dearth of studies on the process occurring in crop plant rhizospheres, where heterotrophic S oxidizers are particularly active. The role of microorganisms in S oxidation in atmospheric S-polluted soils is largely overlooked, although it is clear that microbial oxidization of reduced S does occur in ecosystems that receive particulate deposits from pollution sources—such as, coking and smokeless fuel plants.
141 citations
TL;DR: Short-term inhibitory effect on the total bacterial population was observed after chlorpyrifos and quinalphos applications in the groundnut fields, which recovered within 60 days after seed treatment and by 45 days of soil treatment.
128 citations
TL;DR: The widespread use of insecticides over the past 30 years has resulted in problems caused by their interaction with natural biological systems, and the complex interrelationship of these systems is illustrated in Figure 1.
Abstract: The widespread use of insecticides over the past 30 years has resulted in problems caused by their interaction with natural biological systems. The complex interrelationship of these systems is illustrated in Figure 1. A problem due to contamination by residues may appear far removed from the initial point of introduction into the environment. For example, while some insecticides are intentionally applied directly to the soil to control soil insects, the soil is also a repository for chemicals from drift during foliar application, plant residues containing insecticides and their degradation products, and chemicals deposited by atmospheric precipitation. The persistence of insecticides and their degradation products depends on how deeply they are mixed into the soil; even the most persistent compounds disappear relatively quickly when on the soil surface, yet when incorporated into the soil they are very persistent (Edwards 1966). Generally insecticide residues will occur in the top 6 in. of soil (Chisholm et al. 1950, Harris and Sans 1969, Lichtenstein et al. 1962). This is also the region of greatest activity of soil fauna and flora (Alexander 1961), thus setting the stage for interaction of insecticide residues with the fauna and flora of the soil ecosystem. Recent monographs have considered the effects of insecticides on soil fauna (Edwards and Thompson 1973) and aquatic microorganisms (Ware and Roan 1970).
105 citations
References
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TL;DR: WALKLEY as discussed by the authors presented an extension of the DEGTJAas discussed by the authorsF METHOD for determining soil organic matter, and a proposed modification of the CHROMIC ACID TITRATION METHOD.
Abstract: AN EXAMINATION OF THE DEGTJAREFF METHOD FOR DETERMINING SOIL ORGANIC MATTER, AND A PROPOSED MODIFICATION OF THE CHROMIC ACID TITRATION METHOD A. WALKLEY;I. BLACK; Soil Science
17,132 citations
TL;DR: In this article, an experiment is described in which soils with carbon contents ranging from about 1 to 7 per cent (Walkely-Black, uncorrected) were air-dried for 3, 6, 9, 12, and 15 weeks and then remoistened.
Abstract: An experiment is described in which soils with carbon contents ranging from about 1 to 7 per cent (Walkely-Black, uncorrected) were air dried for 3, 6, 9, 12, and 15 weeks and then remoistened. The amounts of carbon mineralised and ammonia and nitrate-nitrogen subsequently produced during 19 days were then determined and compared with the amounts mineralised from a non-dried soil. For a given drying period the amounts of carbon and nitrogen mineralised were proportional to the carbon content of the soil while, for a given soil, they were found to be a significant linear function of the log of the time the soil was in an air-dry state prior to moistening. With high-humic soils drying produced extra nitrogen on moistening sometimes equivalent to over 1 ton of sulphate of ammonia per acre. Even with low-humic soils values of about 300 pounds were common. The results of the drying effect are tabulated both in conventional units and as pounds of sulphate of ammonia per acre 6″. In the latter units the table should more readily serve as a general guide in applying the results. The application of the results to nitrogen fertiliser trials, irrigation, rundown of soil fertility and soil carbon, the effect of shadeetc. is then discussed. The material and mechanism possibly involved is also considered. The results should be of fairly wide application since a basic principle operating on material (humus) of more or less uniform composition and common to all soils is involved.
348 citations
167 citations
TL;DR: In this paper, the degree by which metabolic activity increases in remoistened air-dried soils varies directly with the concentrations of free amino acids and other nitrogenous materials released by the air drying process.
Abstract: Comparative studies on the respiration of four air-dried and fresh soils show that in all cases a higher level of metabolic activity is attained in the air-dried soils following remoistening. The degree by which metabolic activity increases in remoistened air-dried soils varies directly with the concentrations of free amino acids and other nitrogenous materials released by the air drying process. No appreciable gas exchange was noted through chemical action alone and it is felt that the increased respiration of air-dried samples over fresh soils is due mainly to biological activity. Quantitative studies of the bacterial flora of air-dried soils indicate a short lag period followed by a phase of logarithmic increase during the early stages following remoistening. These results are discussed in terms of the bacterial population existing after air drying and its relationship to the high respiratory activity observed.
162 citations
TL;DR: Pesticide concentrations greatly in excess of those recommended for agricultural and home use were required to produce an effect, and supplementary organic matter tended to reduce pesticide toxicity and increase the microbial degradation of pesticides in soil.
Abstract: The influence of 29 pesticides on CO2 production and nitrification by soil microorganisms was determined. A few compounds were stable but without significant effect in soil (chlorinated hydrocarbons), some persisted and depressed respiration and nitrification (carbamates, cyclodienes, phenylureas, thiolcarbamates), and others displayed toxicity but were transformed by soil microorganisms (amides, anilides, organophosphates, phenylcarbamates, triazines). Some compounds of the last type induced an initial increase and subsequent decrease in CO2 production by soil. No simple explanation of this effect is possible, but the results of studies of model systems having established activities suggest that in soil any one or a combination of the following mechanisms is responsible for the observed complex relation of CO2 production to time: (i) a pesticide acts to uncouple oxidative phosphorylation in a manner analogous to 2,4-dinitrophenol; (ii) a pesticide lacking antimicrobial action is oxidized in part and transformed to a stable and toxic product; (iii) a pesticide that is selectively toxic inhibits CO2 production by sensitive microorganisms but is subject to oxidation without detoxification by other members of the microbial population that are resistant to its initial action. Pesticide concentrations greatly in excess of those recommended for agricultural and home use were required to produce an effect, and supplementary organic matter (glucose) tended to reduce pesticide toxicity and increase the microbial degradation of pesticides in soil.
114 citations