103(1)_str5

ISSN 1392-3196 / e-ISSN 2335-8947
Zemdirbyste-Agriculture, vol. 103, No. 1 (2016), p. 35–44
DOI 10.13080/z-a.2016.103.005

Heavy metal sorption capacity and mobility in the Retisol profile in relation to the contamination

Algirdas MOTUZAS, Rimantas VAISVALAVIČIUS, Nomeda SABIENĖ

Abstract

The aim of the research was to evaluate heavy metal contamination, heavy metal sorption capacity and their mobility in the monoliths of the relatively natural and technogenically affected by vehicle emissions Retisol profile.

Two objects of the Eutric Albic Stagnic Bathygleyic Glossic Retisol were investigated: 1^st – relatively natural (350 m from motorway) and 2^nd – technogenically affected 20 m from motorway). Total heavy metal amounts in each horizon of the soil profile were determined by flame atomic absorption spectrometry method in the digestate of the HF + HNO₃ + HCl, and mobile heavy metal amounts – in the extract of 1 M CH₃COONH₄ (pH 4.8). In the relatively natural soil, elevated Pb amounts were observed at the topsoil to 10 cm, and Cu – at the depth to 60 cm while Zn contamination was not observed. While heavy metal contamination of the technogenically affected Retisol was observed throughout the soil profile to one meter. Percentage of the mobile Pb from total amount in the natural and technogenically affected soil was 11.1–19.6% and 16.7–19.3%, Cu – 13.0–16.7% and 16.1–19.5%, Zn – 18.3–22.5% and 16.4–21.0%, respectively.

Special stands of the model columns (1 m height, 0.15 m diameter) were designed and filled up with undisturbed soil monoliths. Heavy metal sorption capacity and mobility both in the soil profile and each horizon were investigated when saturating them with mixture of Pb, Zn and Cu solutions. Heavy metal sorption capacity in the horizons of the Retisol profile varied in the range of 504.40–819.60 mg kg^-1 for Pb, 498.27–905.63 mg kg^-1 for Cu and 505.07–983.43 mg kg^-1 for Zn as well as enrichment factor – 27.4–70.8, 36.0–59.5 and 17.5–53.2, respectively. Percentage of the mobile Pb, Cu and Zn in the saturated natural and technogenically affected soil was 40.6–48.2, 40.4–45.7 and 40.7–48.9 %, respectively.

Consequently, despite the great heavy metal sorption capacity, their mobility and potential bioavailability increase markedly in the contaminated Retisol, therefore it is important in the legislations of the food safety and agricultural land protection to strengthen measures of the environmental protection at roadsides, such as sanitary zones of at least 20 m.

Key words: agricultural land, enrichment factor, heavy metal mobility, model columns, sorption capacity, vehicle emissions, Retisols.

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