Distribution and availability of copper in aggregate size fractions of some calcareous soils
The difference in copper (Cu) availability between soils can be a result of different distribution of Cu forms in various size fractions of aggregates. This study aimed to determine different Cu forms in bulk soils and aggregate size fractions of some heavy metal-contaminated soils from Isfahan Province, Iran and to examine the relationship between Cu forms associated with different soil aggregates and plant indices.
Materials and methods
Bulk soil of five contaminated soils was partitioned into four aggregate size fractions (2.0 to 4.0 mm (large macro-aggregates), 0.25 to 2.0 mm (small macro-aggregates), 0.05 to 0.25 mm (micro-aggregates), and < 0.05 mm (mineral fraction)) by dry sieving. Copper was fractionated into soluble and exchangeable (F1), carbonate-bound (F2), Fe-Mn oxide-bound (F3), and organic-bound (F4) by Tessier’s method. Copper concentration and dry weight of shoots and roots of corn (corn indices) were determined in a pot experiment to assay the Cu availability in the five studied soils. Relationship between the Cu bound to different chemical fractions in different size aggregates and corn indices was assessed using cluster analysis.
Results and discussion
The results showed that the 0.25–2.0-mm fraction, with the highest mass percentage in the soils, had higher contribution to the total content of Cu in the bulk soils. Copper was mainly associated with the organic-bound and residual fractions in the bulk soils and aggregates. Principal component analysis (PCA) represented that the distribution patterns of Cu chemical fractions in different aggregates were strongly related to the soil type. The study of relationship between Cu fractions and the corn indices demonstrated that the organic-bound fraction of Cu in 2.0–4.0 mm aggregates was remarkably correlated with the Cu concentration in corn root and suggested that the organic-bound fraction of Cu in larger aggregates constitutes the chief plant-available Cu pool in the soils.
Soil type and aggregate size distribution were important factors controlling availability and distribution patterns of Cu fractions in studied soils. The organic-bound fraction of Cu in the larger aggregate fractions appeared to be more readily available for plant than in the smaller aggregate fractions. Therefore, soil aggregate size fractionation can be used to assess the distribution, bioavailability, and environmental hazard of Cu in soils.
KeywordsChemical fractions Copper availability Pollution Soil physical fractions
This study supported by funds allocated by the Vice President for research of Shahrekord University (Iran).
- Chapman HD, Pratt PF (1961) Methods of analysis for soils, plants, and waters. University of California, Riverside, CAGoogle Scholar
- Chen Z, Pawluk S, Juma NG (1998) Impact of variations in granular structures on carbon sequestration in two Alberta Mollisols. In: Lal R et al (eds) Soil processes and the carbon cycle. Adv. Soil Sci. CRC Press, Boca Raton, FL, pp 225–243Google Scholar
- Dankoub Z, Khademi H, Ayoubi S (2012) Magnetic susceptibility and its relationship with the concentration of selected heavy metals and soil properties in surface soils of the Isfahan region. J Environ Study 38(63):4–6Google Scholar
- Gee GW, Bauder JW (1986) Particle size analysis. In: Klute A (ed) Methods of soil analysis. Part 1, 2nd edn. ASA and SSSA, Madison, WI, pp 404–407Google Scholar
- Loeppert RH, Suarez DL (1996) Carbonate and gypsum. In: Sparks DL (ed) Methods of soil analysis. Soil Science Society of America Journal, Madison, pp 437–474Google Scholar
- Neu S, Müller I, Brackhage C, Galazka R, Siebielec G, Puschenreiter M, Dudel EG (2018) Trace elements bioavailability to Triticum aestivum and Dendrobaena veneta in a multielement-contaminated agricultural soil amended with drinking water treatment residues. J Soils Sediments 18:2259–2270CrossRefGoogle Scholar
- Sumner ME, Miller PM (1996) Cation exchange capacity and exchange coefficient. In: Sparks DL (ed) Methods of soil analysis. Soil Science Society of America Journal, Madison, pp 1201–1230Google Scholar
- Venditti D, Durécu S, Berthelin J (2000) A multidisciplinary approach to assess history, environmental risks, and remediation feasibility of soils contaminated by metallurgical activities. Part A: chemical and physical properties of metals and leaching ability. Arch Enviro Con Tox 38(4):411–420CrossRefGoogle Scholar