Showing papers in "Environmental Science & Technology in 1968"

Chemistry of manganese in Lake Mendota, Wisconsin

Abstract: The environmental water chemistry of manganese was studied under field and laboratory conditions. Mn(II) was the principal form of Mn measured in Lake Mendota, Wisconsin, throughout an entire seasonal cycleOnly Mn(II) was detected in anoxic waters, whereas both Mn(II) and Mn oxides were present in oxygenated waters. Rates of oxidation of Mn(II) appeared to be slow in the environment and the effect of pH seemed important. Sorption reactions of Mn(II) with Mn and Fe oxides occurred during oxygenation processes and were probably part of the mechanism involved in the removal of Mn from the water column. The presence of Mn(II) in reducing environments yielded rare computed supersaturated conditions with respect to MnCO3, and MnS. These compounds may have limited Mn(II) solubility on those occasions.

Biodehalogenation. Reductive Dehalogenation of the Biocides Ethylene Dibromide, 1,2-Dibromo-3-chloropropane, and 2,3-Dibromobutane in Soil.

Abstract: T nature of the interaction of polyhalo-organic biocides with the soil matrix in which they are placed must be considered an important feature in the understanding of man's alteration of thi~ :'spect of his environment. Unlike cisand trans-1,3-dichloropropane (Castro and Belser, 1966) the broad range biocides ethylene dibromide and 1 ,2-dibromo-3-chloropropane, widely employed as nematocidal soil fumigants, are not readily hydrolyzed in aqueous milieu. Consequently the persistence of these substances in soil would be expected to be limited by their volatility rather than by any chemkal or biological conversion in the soil matrix. Indeed, the relatively long term effectiveness of 1,2dibromo-3-chloropropane as a nematocide has been noted (Baines, 1962; Ichikawa, Gilpatrick, eta/., 1955). However, neutron activation analyses (Castro and Schmitt, 1962) of a variety of extracted plant materials (Thomason, Baines, et a/., 1963) confirm earlier findings that no organic bromide is present in plants grown in soil which has been treated with either of these substancLs. There is, however, an increase in the bromide ion content of such plants, and residue tolerances have been set on this basis. Although preliminary greenhouse experiments from these laboratories indicate orange seedlings can take up these substances intact, an assessment of the dominance of the dehalogenation of these entities in soil or in plants remains to be made. The present work demonstrates that a significant biological dehalogenation of these toxicants as well as other vicinal dibromides does occur in soil.

Fluoroorganic acids in soybean leaves exposed to fluoride

Abstract: Soybean plants were fumigated with HF or grown in nutrient solution containing sodium fluoride or fluoroacetate, and the organic acid fractions of the leaf extracts were compared. Organic acid extracts from these treatments contained fluoroorganic compounds that were chromatographically similar to fluoroacetate and fluorocitrate. These fractions were separated from HF- and NaF-treated leaf extracts and found to inhibit aconitase prepared from either pig heart or soybean fluorocitrate. Aconitase from soybean leaves was as sensitive to fluorocitrate as that isolated from pig heart. Fluorocitrate was identified in extracts of fluoride-treated plants by infrared spectroscopy.

Determination of Gases in Sediments

Abstract: Author(s): Reeburgh, WS | Abstract: A method was developed for sampling and analysis of gases contained in interstitial water. Interstitial water was separated from sediments with a filter press-type sediment squeezer and transferred to a specially designed sampler-stripper. Gases contained in the interstitial water were stripped from solution and analyzed by gas chromatography. Argon, N2, and CH4 have been measured in sediments. The technique can be used to measure total CO2 and H2S with minor modifications. © 1968, American Chemical Society. All rights reserved.