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Residue disappearance and leaching of 14C‐allyl‐alcohol from different soils were studied in laboratory experiments. Additionally, the uptake of residues by lettuce and carrots was investigated in the greenhouse. In laboratory experiments, residue disappearance and leaching from soils was correlated negatively to the organic matter content. In greenhouse experiments with a sandy loam soil at an application rate normally used in practice, an average of 12.5 % of the applied radioactivity was recovered after an eight day interval between application and sowing. Furthermore, an average of 8 % (sum in soil and plants) of the applied radioactivity was recovered after lettuce or carrot growing. Uptake of residues was higher by carrots than by lettuce, and higher by lettuce roots than by lettuce tops. No bioaccumulation was observed. The residues in soils and plants were, to a high percentage, unextractable and, to a smaller extent, fully water‐soluble products. Unchanged allylalcohol could not be detected by the analytical methods used. [ABSTRACT FROM PUBLISHER]

Mass balance and fate of atrazine‐ 14C and pentachlorophenol‐ 14C (PCP‐ 14C) were studied in short‐term tests in a closed aerated laboratory soil‐plant system, using two concentrations in soil and two plant species, as well as under outdoor conditions for one vegetation period. In the laboratory, for both pesticides bioaccu‐mulation factors of radiocarbon taken up by the roots into plants were low. They were higher for lower (1 ppm) than for higher soil concentrations (6 ppm for atra‐zine, 4 ppm for pentachlorophenol) and varied with the plant species. Mineralization to 14CO2 in soil was negatively related to soil concentration only for PCP‐ 14C. Conversion rates in soil including the formation of soil‐bound residues were higher for the lower concentrations of both pesticides than for the higher ones; conversion rates in plants were species‐dependent. In 14 terms of CO2 formation and of conversion rates, PCP was less persistent in soil than was atrazine. For both pesticides, laboratory data on conversion and mineralization gave a rough prediction of their persistence in soil under long‐term outdoor conditions, whereas bio‐accumulation factors in plants under long‐term outdoor conditions could not be predicted by short‐term laboratory experiments. [ABSTRACT FROM PUBLISHER]

Different methods were tested for their suitability to assess the effects of chemicals on soil microbial activity: determination of ATP‐content, respiration and fluorescein diacetate (FDA) hydrolysis. Fresh soil was either used immediately or amended with 0.5 % alfalfa meal, in order to improve the conditions of the microorganisms. The chemicals were applied in concentrations of 2, 20 and 200/μg.g‐1 . As herbicides, atrazine, pentachlorophenol, 4‐chloroaniline and chloroacetamide were used, as fungicides zineb (zinc ethylene‐1,2‐bis‐dithiocarbamidate) and captan (n‐trichloromethylthiote‐trahydrophthalimide), as insecticides lindane (γ‐hexachlorocyclohexane) and 4‐nitrophenol, and as a bactéricide, HgCl2. The observations were limited to 48 days. The effects caused by atrazine, lindane and cap‐tan were minor. The remaining pesticides induced measurable changes in the behaviour of microorganisms: while higher concentrations caused mostly reversible or irreversible reductions in ATP‐content and in FDA‐hydrolysis, small concentrations sometimes produced stimulative effects. The production of CO was stimulated by several pesticides in various concentrations. Improvement of soil by the addition of alfalfa meal promoted the reversibility of effects caused by chemicals. [ABSTRACT FROM PUBLISHER]

Immediately after application of chloroalkylene-9-C to soil (1.32 ppm, based on dry weight of soil in the upper layer of 0 to 10 cm) under outdoor conditions, carrots were sown; in the following year, sugar beets were grown. About 80% of the radioactivity applied volatilized within one vegetation period. Most of the remaining radioactivity was still in the upper soil layer; 0.8% had dispersed to a depth of 40 cm, and 3.3% was taken up by the carrot plants. In the second year, no more decrease of soil residues was observed; uptake by sugar beets was 0.1% of the applied radioactivity. In the first year, the residues in the upper soil layer consisted of 41% unchanged chloroalkylene-9, 19% soluble metabolites, and 40% unextractable residues; the amount of unextractable residues rose to 68% in the second year. The following conversion products were characterized in the soil extracts: a monohydroxylated dichlorobiphenyl, a monomethoxylated dichlorobiphenyl, and two isomeric monohydroxylated, monoisopropylated dichlorobiphenyls; in carrot roots, a monomethoxylated dichlorobiphenyl was detected. Conjugates occurring in the soil yielded, after acid hydrolysis, a monohydroxylated dichlorobiphenyl among other compounds. [ABSTRACT FROM AUTHOR]

Seasonal effects of liming, irrigation, and acid precipitation on microbial biomass N and some physicochemical properties of different topsoil horizons in a spruce forest ( Picea abies L.) were measured throughout one growing season. The highest biomass N was recorded in autumn and spring in the upper soil horizons, while the lowest values were obtained in summer and in deeper horizons. The clearest differences between the different soil treatments were apparent in autumn and in the upper horizons. Liming increased the microbial biomass N from 1.7% of the total N content to 6.8% (Olf layer) and from 1% to 2% of the total N content in the Of layer. The main inorganic-N fraction in the deeper horizons was NO. An increase in cation exchange capacity was observed down to the Oh layer, while soil pH was only slightly higher in the Olf and Of layers after liming. The effects of irrigation were less marked. The microbial biomass N increased from 1.7% of total N to 4.8% in the Olf layer and from 1% to 2% of total N in the Of layer. In the Olf layer an increase in C mineralization was observed. Acid precipitation decreased the microbial biomass N in the upper horizons from 4.8% of total N to 1.8% in the Olf layer and from 2% to 0.5% in the Of layer. No significant changes in soil pH were observed, but the decrease in cation exchange capacity may result in a decrease in the proton buffering capacity in the near future. [ABSTRACT FROM AUTHOR]

The humic monomer catechol was reacted with 14C-isoproturon and some of its metabolites, including 14C-4-isopropylaniline, in aqueous solution under a stream of oxygen. Only in the case of 14C-4-isopropylaniline, incorporation in oligomers, in fulvic acid-like polymers, and in humic acid-like polymers by covalent bonds was observed. The main oligomer was identified by mass spectrometry as a trimer, 4,5-bis-(4-isopropylphenylamino)-3,5-cyclohexadien e-1,2-dione. Biomineralization of 14C-compounds to 14CO2 in a loamy soil and release of 14C from soil columns into percolate water decreased in the order: freeisoproturon >free 4-isopropylaniline>fulvic acid-like polymers>trimer>humic acid-like polymers. In soil columns, a small but measurable migration of 14C from polymers from upper to deeper soil layers could be detected; most of this 14C was bound again in a non-extractable form. It is concluded that aniline-derived pesticides bound in soil by covalent binding may not be fully undegradable,nor fully immobile. [ABSTRACT FROM AUTHOR]

A laboratory model was developed to investigate pesticide volatilization from soil surfaces under various boundary conditions. Carbon-14-labeled terbutylazine (2-chloro-4-ethylamino-6-t-butylamino-1,3,5-triazi ne) was applied to the surface of different soils in doses commonly used in agriculture. Ile experimental setup was designed to study the dynamics of the volatilization process. Short sampling intervals give information about temporal changes in loss rates, which allows to quantify the influence of the application mode. Drop application, for example, leads to volatilization kinetics different from those by spraying, especially in the initial phase. Another aim of the experiments is to describe soil matrix effects on pesticide volatility. After a test period of 10 d the cumulative vapor loss ranged from minimum6.9% (loamy sand) to maximum 23.1% (weakly loamy sand) of the applied 14C-terbutylazine. In the case of a silty loam it was shown that soil moisture had a strong effect on terbutylazine volatilization. Rising the soil water suction resulted in a drastic decline involatility. [ABSTRACT FROM AUTHOR]