Background, aim, and scope Heavy metal (HM) mobility in soil depends on the HM species in it. Therefore, knowledge of the HM speciation in soil allows the prediction of HM impact on the environment. HM speciation in soil depends on the metal chemical origin, soil texture, and other factors such as the origin and level of soil contamination. Recently, the problem of organic waste utilization is of great importance as the amount of this recyclable material is continually increasing. One of the possible ways of recycling is the use of processed organic wastes for agricultural needs. In this research, aerobically composted sewage sludge was used, the utilization of which is of essential importance. But one of the most serious restrictions is HM transfer from such material to the soil. Therefore, a prediction of HM mobility in soil and its migration in the environment is an important issue when using sewage sludge compost (SSC) in agriculture. Zn, Cu, and Pb speciation was performed according to the modified methodology of Tessier et al. (Anal Chem 51:844-851, 1979) in two different (sandy and clay) soils with background HM amounts and in soil samples amended with aerobically digested SSC to find out the predominant species of the investigated HM and to predict their potential availability. Materials and methods The modified method of sequential extraction initially proposed by Tessier et al. (Anal Chem 51:844-851, 1979) is designed for HM speciation into five species where HM mobility decreases in the order: F1-exchangeable HM (extracted with 1 M MgCl 2 at an initial pH of 7 and room temperature), F2-carbonate-bound HM (extracted with 1 M CH 3 COONa buffered to pH 5 at room temperature), F3-Fe/Mn oxide-bound HM (extracted with 0.04 M NH 2 OH·HCl at an initial pH of 2 at 96°C), F4-organic matter-complexed or sulfide-bound HM (extracted with 0.02 M HNO 3 and 30% (v/v) H 2 O 2 at a ratio of 1:1 and an initial pH of 2 at 85°C), and F5-the residual HM (digested with HNO 3 , HF, and HCl mixture). After digestion, HM amounts in solution were determined by atomic absorption spectrometry (AAS 'Hitachi'). Mixtures of uncontaminated soils of different textures (clay and sandy) with SSC in ratios 20:1, 10:1, and 5:1 were used to simulate the land application with SSC. During a period of 7 weeks, changes in Zn, Cu, and Pb content within species were investigated and compared weekly in soil-SSC mixtures with their speciation in pure soil and in the SSC. Results Results in the SSC showed that more HM were found as mobile species compared to the soils, and in sandy soil, more were found in the mobile species than in clay soil. But the HM speciation strongly depended on the metal chemical origin. According to the potential availability, HM ranked in the following order: Zn>Pb>Cu. Zinc generally occurred in the mobile species (F1 and F3), especially in sandy soils amended with SSC, and changes of the Zn speciation were insignificant at the end of the experiment. Pb transfer to insoluble compounds (F5) was evident in the SSC-soil m...
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 + HNO 3 + HCl, and mobile heavy metal amounts -in the extract of 1 M CH 3 COONH 4 (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.
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