Effect of mono and divalent salts on the conformation and composition of a humic acid and on atrazine adsorption
We investigated the effects of sodium and calcium chlorides on the conformation and composition of a purified Aldrich humic acid (PAHA), as well as on the adsorption of atrazine. The PAHA was treated with 1, 10, and 100 mM NaCl, CaCl2, or a mixture of NaCl and CaCl2 (molar ratio 5:1) at pH 7.5 and 8.5. The conformation of treated PAHA was characterized by atomic force microscopy (AFM) and transmission electron microscopy (TEM) and spectral changes of functional groups of PAHA by Fourier transform infrared spectroscopy (FTIR). AFM and TEM images showed an increase in the aggregation of the PAHA as salinity increased. FTIR spectra revealed that changes in the aggregation of the PAHA were principally due to the formation of bridged interactions between calcium and carboxylate groups in the PAHA. The adsorption of atrazine on > 0.45 μm PAHA decreased as salt concentrations and pH increased. This reduction of atrazine adsorption was explained by the decrease in available adsorption sites due to agglomeration of PAHA.
KeywordsHerbicide Organic matter Salinity Sodium Calcium TEM AFM FTIR
This work was supported by CNA-CONACYT (contract no. CNA-2000-01-032) and The Mexican Institute of Water Technology (project no. TH0803.1). A doctoral scholarship was provided by the Mexican National Council for Science and Technology (CONACYT) for Luis Carlos González-Márquez (scholarship number 7430). We would like to thank Prof. James O. Leckie for his very important comments and suggestions as well as for the opportunity to carry out part of this research at the Environmental Engineering Research Laboratory at Stanford University, and Federico Pacheco for his technical support with the TEM and AFM imaging.
- Abate G, Penteado JC, Cuzzi JD, Vitti GC, Lichtig J, Masini JC (2004) Influence of humic acid on adsorption and desorption of atrazine, hydroxyatrazine, deethylatrazine, and deisopropylatrazine onto a clay-rich soil sample. J Agric Food Chem 52:6747–6754. https://doi.org/10.1021/JF049229E CrossRefGoogle Scholar
- APHA, AWWA, WEF (2005) Standard methods for the examination of water and wastewater, 21th edn. American Public Health Association, American Water Works Association, Water Environment Federation, BaltimoreGoogle Scholar
- European Union (2004) COMMISSION DECISION of 10 March 2004 concerning the non-inclusion of atrazine in Annex I to Council Directive 91/414/EEC and the withdrawal of authorisations for plant protection products containing this active substance. THE COMMISSION OF THE EUROPEAN COMMUNITIESGoogle Scholar
- Gilliom RJ, Barbash JE, Crawford CG, et al (2006) The quality of our nation’s waters—pesticides in the nation’s streams and ground water, 1992–2001Google Scholar
- González-Márquez LC, Hansen AM (2009) Adsorción y mineralización de atrazina y relación con parámetros de suelos del DR 063 Guasave, Sinaloa. Rev Mex Ciencias Geológicas 26:587–599Google Scholar
- Hernández-Antonio A, Hansen AM (2011) Uso de plaguicidas en dos zonas agrícolas de México y evaluación de la contaminación de agua y sedimentos. Rev Int Contam Ambie 27:115–127Google Scholar
- Laird DA, Barriuso E, Dowdy RH, Koskinen WC (1992) Adsorption of atrazine on smectites. Soil Sci Soc Am J 56:62. https://doi.org/10.2136/sssaj1992.03615995005600010010x CrossRefGoogle Scholar
- Nakamoto K (1997) Infrared and Raman spectra of inorganic and coordination compounds: part A: theory and applications in inorganic chemistry, 5th edn. Wiley, New YorkGoogle Scholar
- Swift RS (1996) Organic matter characterization. In: Sparks DL, Page AL, Helmke PA, Loeppert RH (eds) Methods of soil analysis part 3 chemical methods. Soil Science Society of America, Madison, pp 1011–1069Google Scholar
- Wall NA, Choppin GR (2003) Humic acids coagulation: influence of divalent cations. Appl Geochem 18(10):1573–1582Google Scholar
- Yeo AR, Flowers TJ (1985) The absence of an effect of the Na/Ca ratio on sodium chloride uptake by rice (Oryza sativa L.). New Phytol 99:81–90. https://doi.org/10.1111/j.1469-8137.1985.tb03638.x CrossRefGoogle Scholar