Dissolved organic matter (DOM) in soil solution is considered to interact with herbicides enhancing their mobility and promoting subsequent leaching.
Batch experiments were conducted to test if free and DOM-bound herbicides can be separated by a DOM-flocculation technique with Cu as a coagulant.
DOM was extracted from the H and A horizons of two soils (Terric Histosol, Cumuli-Calcaric Cambisol) and from the O horizon of a forest soil (Humic Cambisol). DOM-solutions (100 mL) were fortified with the herbicides terbuthylazine and pendimethalin (100 μg active ingredient each) and equilibrated for 14 hours. After DOM-flocculation with Cu (addition of 0,5 mM CuCl2) herbicide recovery was determined in the supernatant solutions and in the precipitate of Humic Cambisol-DOM, respectively.
Recovery of the herbicides from pure water was 85–99% and was not influenced by the addition of Cu. At low pH (4,8–5,3) DOM-flocculation of different DOM-extracts was insufficient and varied in a range of 18 – 90%. Herbicide recovery from DOM-solutions decreased moderately for terbuthylazine (60–90%) and strongly for pendimethalin (5 – 30%). In general, the addition of Cu caused no further reduction of herbicide recovery from supernatant solutions, except for Humic Cambisol-DOM. The effects of Cu-addition were most evident for pendimethalin (strongly reduced concentration in the supernatant solutions) and were considered to be caused by a flocculation of DOM-bound moieties. Flocculation of Humic Cambisol-DOM increased from 18 – 24% at pH 5 to > 95% at pH 8. However, at this pH the formation of Cu(OH)2 as a sorbing subcomponent of the flocculated matter lead to an overestimation of DOM-bound pendimethalin. Calculating this side effect 6% of pendimethalin added was DOM-bound. Only traces of terbuthylazine (< 1%) were found in the solid matter of flocculated Humic Cambisol-DOM.
To sum up, the new approach to separate freely dissolved herbicides from DOM-bound moieties not fully corresponded to our expectations. DOM-flocculation was found to depend strongly on pH-environment influencing not only DOM-herbicide interactions but also the clear separation of DOM-bound herbicides from herbicides in solutions.
Carter, C.W.;I.H. Suffet (1982): Binding of DDT to Dissolved Humic Materials. Environ. Sci. Technol.16, 735–740CrossRefGoogle Scholar
Chiou, C.T.;D.E. Kile;T.I. Brinton;R.L. Malcom;J.A. Leenheer (1987): A comparison of water solubility enhancements of organic solutes by aquatic humic material and commercial humic acids. Environmental Science & Technology18, 916–922Google Scholar
Dankwardt, A.;B. Hock;R. Simon, D. Freitag;D. Kettrup (1996): Determination of non-extractable triazin residues by enzyme immunoassay: Investigation of model compounds and soil fulvic and humic acids. Environmental Science & Technology30, 3493–3500CrossRefGoogle Scholar
Gamble, D.S.;M.I. Haniff;R.H. Zienius (1986): Solution Phase Complexing of Atrazine by Fulvic Acid: A Batch Ultrafiltration Technique. Anal. Chem.58, 727–731CrossRefGoogle Scholar
Gauthier, T.D.;E.C. Shane;W.F. Guerin;W.R. Scitz, C.L. Grant (1986): Flourescence quenching method for determining equilibrium constants for polycyclic aromatic hydrocarbons binding to dissolved humic materials. Environ. Sci. Technol.20, 1162–1166CrossRefGoogle Scholar
Govi, M.;A. Sarti;E. Di Martino;C. Ciavatta;N. Rossi (1996): Sorption and Desorption of Herbicides by Soil Humic Acid Fractions. Soil Science161, 265–269CrossRefGoogle Scholar
Haniff, M.I.;R.H. Zienius;C.H. Langford;D.S. Gamble (1985): The solution phase complexing of atrazine by fulvic acid: Equilibria at 25°C. J. Environ. Sci. Health B20, 215–226Google Scholar
Hayes, M.H.B. (1970): Adsorption of triazine herbicides on soil organic matter, including a short review on soil organic matter chemistry. Residue Review32, 131–174Google Scholar
Johnson, W.E.;N.J. Fendinger;J.R. Plimmer (1991): Solid-Phase Extraction of Pesticides from Water: Possible Interferences from Dissolved Organic Material. Anal. Chem.63, 1510–1513CrossRefGoogle Scholar
Kördel, W.;M. Dassenakis;J. Lintelmann;S. Padberg (1997): The importance of natural organic material for environmental processes in waters and soils. IUPAC, Pure and Applied Chemistry69, 1571–1600CrossRefGoogle Scholar
Kolouskova, N. (1987): Interaction of Humic Acids with Atrazine. J. Environ. Sci. Health B22, 113–123CrossRefGoogle Scholar
Landrum, P.F.;S.R. Nihart;B.J. Eadies;W.S. Gardener (1984): Reverse-Phase Separation Method for Determining Pollutant Binding to Aldrich Humic Acid and Dissolved Organic Carbon of Natural Waters. Environ. Sci. Technol.18, 187–192CrossRefGoogle Scholar
Laor, Y.;M. Rebhun (1997): Complexation-flocculation: A new method to determine binding coefficients of organic contaminants to dissolved humic substances. Environmental Science & Technology31, 3558–3564CrossRefGoogle Scholar
Madhun, Y.A.;I.L. Young;V.H. Freed (1986): Binding of herbicides by water soluble organic materials from soil. J. Environ. Qual.15, 64–68Google Scholar
Maxin, C.R.;I. Kögel-Knabner (1995): Partitioning of polycyclic aromatic hydro-carbons (PAH) to water-soluble soil organic matter. European Journal of Soil Science46, 193–204CrossRefGoogle Scholar
McCarthy, J.F.;B.D. Jiminez (1985): Interaction between polycyclic aromatic hydro-carbons and dissolved humic material: Binding and dissociation. Environ. Sci. Technol.19, 1072–1076CrossRefGoogle Scholar
Müller-Wegner, U. (1983): Neue Erkenntnisse zur Wechselwirkung zwischen s-Triazinen und organischen Stoffen in Böden. Dissertation, Universität Göttingen/ GermanyGoogle Scholar
Piccolo, A.;G. Celano;C. De Simone (1992): Interactions of atrazine with humic substances of different origins and their hydrolysed products. The Science of the Total Environment117/118, 403–412CrossRefGoogle Scholar
Rebhun, M.;S. Meir;Y. Laor (1998): Using dissolved humic acid to remove hydrophobic contaminants from water by complexationflocculation process. Environ. Sci. Technol.32, 981–986CrossRefGoogle Scholar
Schnitzer, M.;S.U. Khan (1972): Humic Substances in the Environment, Marcel-Dekker Verlag, New York, page 225Google Scholar
Schomburg, C.J.;D.E. Glotfelty;J.N. Seiber (1991): Pesticide occurence in fog collected near Monterey, California. Environ. Sci. Technol.25, 155–160CrossRefGoogle Scholar
Senesi, N. (1992): Binding mechanisms of pesticides to soil humic substances. The Science of the Total Environment123/124, 63–76CrossRefGoogle Scholar
Senesi, N.;G. Brunetti;P. La Cava;T.M. Miano (1994): Adsorption of Alachlor by humic acids from sewage sludge and amended and non-amended soils. Soil Science157, 176–184CrossRefGoogle Scholar
Senesi, N.;C. Testini (1980): Adsorption of some Nitrogenated Herbicides by Soil Humic Acids. Soil Science130, 314–320CrossRefGoogle Scholar
Stevenson, J.F. (1972): Organic matter reactions involving herbicides in soil. J. Environ. Qual.1, 333–343CrossRefGoogle Scholar
Sullivan, J.D. Jr.;G.T. Felbeck, Jr. (1968): A study of the interaction of s-Triazine Herbicides with Humic Acids from three different soils. Soil Science106, 42–52CrossRefGoogle Scholar