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Heavy Metal Release from Soils in Batch pHstat Experiments
Author(s) -
Schwarz Andreas,
Wilcke Wolfgang,
Zech Wolfgang,
Stýk Jan
Publication year - 1999
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1999.03615995006300020006x
Subject(s) - chemistry , soil water , metal , dissolution , metal ions in aqueous solution , adsorption , ion exchange , nuclear chemistry , titration , environmental chemistry , inorganic chemistry , ion , organic chemistry , environmental science , soil science
In Slovakia H + input into soils is increasing because alkaline dust emissions have been reduced since 1990. Our objectives were to examine (i) the metal release in H + buffer reactions of Slovak soils and (ii) the impact of the proton buffering on heavy metal partitioning. We used 10 soils (pH 7.4–3.6) in a batch pH stat experiment. Released ions were adsorbed to an ion‐exchange resin, while pH was kept constant. After reaction times of 10 min, 30 min, 1, 2, 4, 24, 48, and 96 h, soil and ion‐exchange resin were separated and ions were extracted from the resin. After 0, 4, and 96 h, we determined metal concentrations in seven fractions. On average, the total release after 96 h (in percentage of the total concentration) decreased in the order: Cd (74) > Pb (59) > Cu (29) > Zn (22) > Ni (17) > Cr (3.1), while the initial release rate into solution decreased in the order: Cd > Zn > Ni > Cu > Pb > Cr. After 48 h, only the Cr release rate was lower than that of Cd. Particularly in less acid soils, Pb, Cu, Zn, and Cd released by the dissolution of oxides were adsorbed onto the soil matrix, explaining the slower decrease of the Pb and Cu release rates. The percentages of weakly bound heavy metals decreased more markedly during the titration than those of metals bound to Fe oxides. Increased H + inputs into Slovak soils will cause enhanced metal release into soil solution.