The potential ecological risk of soil trace metals following over five decades of agronomical practices in a semi-arid environment

ABSTRACT

The concentration and potential ecological risk of Mn, Zn, Cu, and Cd in the surface soils (0–30 cm) belonging to 12 soil profiles and 4 soil types (Vertisols, Chernozems, Calcisols, and Cambisols) from the cultivated soils and the corresponding uncultivated soils were investigated. Long-term cultivation caused a considerable build-up diethylene-triamine pentaacetic acid (DTPA)-extractable Mn (7–55%), and Cd (12–31%) as well as the total form of Zn (3–14%), Cu (8–25%), and Cd (33–78%) in all soil types. Following long-time cropping, total Zn (mean = 73 mg kg⁻¹), Cu (mean = 33 mg kg⁻¹), and Cd (mean = 3.14 mg kg⁻¹) and DTPA Zn (mean = 1.2 mg kg⁻¹) and Cu (mean = 2.44 mg kg⁻¹) were below their maximum allowable limits. However, the average amount of DTPA Cd in the tilled soils (min = 0.4, max = 0.75, mean = 0.55 mg kg⁻¹) was above its maximum permissible limit mainly due to the over application of phosphate fertilisers and the pesticides. Considering the potential ecological risk (RI) assessment of the cultivated soils (min = 44, max = 70, mean = 54), the soil types were categorised as low (RI ≤ 50) to moderate (50 < RI ≤ 100) potential ecological risk.

KEYWORDS:

• Soil
• ecological risk
• trace metal
• total form
• DTPA-extractable fraction

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Salar Rezapour is associate professor at Soil Science Department, Urmia University, Urmia, I.R. Iran. He holds a PhD degree in Soil Science, Tabriz, I.R. Iran. His research focuses on environmental earth science, soil pollution, and geochemistry. He is the author (or co-author) of over 30 articles published in the international journals.

P. Kouhinezhad is an MSc student at Soil Science Department, Urmia University, Urmia, I.R. Iran.

A. Samadi is professor at Soil Science Department, Urmia University, Urmia, I.R. Iran. He holds a PhD degree in Soil Science, from the University of Western Australia, Australia. His research focuses on soil chemistry and fertility. He is the author (or co-author) of over 20 articles published in the international journals.

Additional information

Funding

The authors wish to thank the Urmia University for the financial support of this research (grant No. 10/1142).