Selective absorption of heavy metals by soil and humic acids at different pH levels

N. N. Miroshnychenko; O. A. Kutz

doi:10.15421/041607

N. N. Miroshnychenko National Scientific Center «O. N. Sokolovsky Institute for Soil Science and Agrochemistry Research»
O. A. Kutz National Scientific Center «O. N. Sokolovsky Institute for Soil Science and Agrochemistry Research»

Keywords: soil, humic acids, heavy metals, absorption, pH

Abstract

Studying processes of sorption-desorption of heavy metals from soil and its individual components allow to predict long-term effects under conditions of multielement contamination. Cations of heavy metals are showing competitive relationship due to their specific adsorption by components of the soil absorption complex, in particular humic acids. Interaction of chernozem podzolized heavy loam, isolated preparation of humic acids and soil residue after its removal with the solution which contain sulphates of Zn, Cd, Ni, Co and Cu in equal ratio were simulated at different pH levels. The task of research was to compare selective absorption of some heavy metals in soil and humic acids at pH values from 3 to 9. The experiment was performed by mixing 10 g of soil material or 0.1 g of humic acid with 100 ml of buffer solution, adding 10 ml 0.01 n equal mixture of Cd, Zn, Ni, Co, Cu and 2-hour exposure. Humic acids were extracted from this soil by 0.1 n NaOH after decalcification using 0.05 n H₂SO₄. Crystalline Copper sulphate, Zinc, Nickel, Cobalt, Cadmium were used to prepare the solution level of heavy metals. Ammonium acetate-buffer solutions with different pH (3.0, 5.0, 7.0, 9.0) were obtained by varying the ratio CH₃СOOH and NH₄OH. The experiment showed that competitive relationship between heavy metal in soil and humic acids. Copper has the highest specificity adsorption, Cobalt – the smallest. Under acidic and strongly acidic reaction content of Zn, Cd, Ni in equilibrium solution is close enough. The absorption of copper was increased by 50 % from strongly acidic to neutral reaction. Under alkaline conditions Cobalt and Copper were practically absent in the solution. Has been found that the absorption of heavy metals by soil decreases in sequence: Cu, Zn > Cd, Ni > Co. The selectivity of the absorption of heavy metals by humic acids was less marked, but the ability to sorption has the similar sequence: Cu > Zn > Ni > Cd > Co. The residue of soil after removal of humic acids has a high affinity for copper ions, which was absorbed twice from each other metals. Has been proved experimentally that selective adsorption of heavy metals in soil significantly depends on the pH, decreasing under acidic and strongly acidic conditions where hydrogen is successfully competing with them for exchange places in soil absorption complex. Deviation from the equivalent absorption (20 %) of each heavy metal in soil accounted for 15.0–26.0 % in acidic pH and 1.6–45.4 % in alkaline pH. After the interaction of heavy metals with humic acids in the most acidic medium fluctuations content elements in the equilibrium solution was 15.7–25.3 %, while the highest pH 11.0–26.7 %. Overall, the decrease of sorption capacity for humic acids elements can be placed in the following order: Cu > Zn > Ni > Cd > Co. This sequence is saved by a narrow ratio solution: adsorbent. Thus, under condition of polyelement contamination migration of Cobalt in soil may be more intensive than Zink, Cadmium, Nickel and a lot more than Copper, especially in alkaline pH.

References

Angehrn-Bettinazzi, C., Thoni, L., Hertz, J., 1989. An attempt to evaluate some factors affecting the heavy metal accumulation in a forest stand, International Journal of Environment Analytic Chemistry, 35, 69–79.
Anisimov, V. S., Kochetkov, I. V., Kruglov, S. V., Aleksahin, R. M., 2011. Vliyanie organicheskogo veschestva na parametryi selektivnoy sorbtsii kobalta i tsinka pochvami i vyidelennyih iz nih ilistyimi fraktsiyami [Influence of organic matter on parameters of selective absorption of cobalt and zinc in soils and isolated from their clay fractions]. Eurasian Soil Science 6, 675–684 (in Russian).
Borůvka, L., Drábek, O., 2008. Heavy metal distribution between fractions of humic substances in heavily polluted soils. Plant, Soil and Environment 50(8), 339–245.
Dergacheva, M. I., Nekrasova, O. A., 2012. Nasyischennost mikroelementami guminovyih kislot pochv raznogo vozrasta i usloviy formirovaniya [Saturation of humic acids from soils of different ages and conditions of formation by trace elements]. Heavy metals and Radionuclides in Environment. Materials of the VII International scientific-practical conference. Semipalatinsk 1, 110–115 (in Russian).
Dobrovolskiy, V. V., 2006. Guminovyie kislotyi i vodnaya migratsiya tyazhelyih metallov [Humic acid and water migration of heavy metals]. Eurasian Soil Science 11, 1315–1321 (in Russian).
Fokin, A. D., Karpuhin, A. I., Radzhabova, P. A., 1996. Mikrobiologicheskaya destruktsiya organicheskogo veschestva kak faktor mobilizatsii trudnorastvorimyih mineralnyih soedineniy [Microbial degradation of organic matter as a factor in the mobilization of sparingly soluble mineral compounds]. Izvestia of Timiryazev Agricultural Academy 3, 97–104 (in Russian).
Gao, K. Z., Pearce, J., Jones, J., Taylor, C., 1999. Interaction between peat, humic acid and aqueous metal ions. Environmental Geochemistry and Health 21, 13–26.
Ilin, V. B., 1985. Tyazhelyie metallyi v sisteme pochva-rastenie [Heavy metals in the soil-plant system]. Nauka, Novosibirsk (in Russian).
Karavanova, E. I., Shapiro, A. D., 2004. Vliyanie vodorastvorimogo organicheskogo veschest-va na pogloschenie tsinka dernovo-podzo-listoy pochvoy [The effect of water-soluble organic substances on the absorption of zinc in sod-podzolic soil]. Eurasian Soil Science 3, 301–305 (in Russian).
Korolev, A. N., 2012. Osobennosti sorbtsii Pb, Cd, Zn guminovyimi kislotami kashtanovyih pochv [Peculiarities of sorption of Pb, Cd, Zn in humic acids of chestnut soils]. Heavy metals and Radionuclides in Environment. Materials of the VII International scientific-practical conference. Semipalatinsk 1, 176–186 (in Russian).
Ladonin, D. V., 1997. Vzaimodeystviya guminovyih kislot s tyazhelyimi metallami [The interaction of humic acids with heavy metals]. Eurasian Soil Science 7, 806−811 (in Russian).
Ladonin, D. V., 2000. Konkurentnyie vzaimootnosheniya ionov pri zagryaznenii pochvyi tyazhelyimi metallami [Competitive relationships of ions in soil under heavy metals contamination]. Eurasian Soil Science 10, 1285–1293 (in Russian).
Ladonin, D. V., Plyaskina, O. V., 2003. Fraktsionnyiy sostav soedineniy medi, tsinka, kadmiya i svintsa v nekotoryih tipah pochv pri polielementnom zagryaznenii [Fractional composition of copper, zinc, cadmium and lead compounds in certain types of soil under polyelement contamination]. Bulletin of Moscow University 1, 8–16 (in Russian).
Minkina, T. M., Motuzova, G. V., Nazarenko, O. G., 2009. Sostav soedineniy tyazhelyih metallov v pochvah [Composition of heavy metal compounds in soils]. Everest, Rostov-na-Donu (in Russian).
Ponizovskiy, A. A., Mironenko, E. V., Kondakova, L. P., 2001. Zakonomernosti pogloscheniya svintsa (II) pochvami pri rN ot 4 do 6 [Regularities of the absorption of lead (II) in soils with a pH of from 4 to 6]. Eurasian Soil Science 7, 817–822 (in Russian).
Ponizovskiy, A. A., Studenkina, T. A., Mironen-ko, E. V., 1999. Pogloschenie ionov medi (II) pochvoy i vliyanie na nego organicheskih komponentov pochvennyih rastvorov [The absorption of copper ions (II) in soil and the effect of organic components of soil solutions on it]. Eurasian Soil Science 7, 850–859 (in Russian).
Teyt, R., 1991. Organicheskoe veschestvo pochvyi [Organic matter of soil]. Mir, Moscow (in Russian).
Tipping, E., Griggith, J., Hilton, J., 1983. The effect of adsorbed humic substances on the uptake of copper (II) by goet-hite. Chroatica Chemica Acta 5, 613–621.