The effects of application of agricultural wastes to firing range soil on metal accumulation inIpomoea aquaticaand soil metal bioavailability

The aim of this study was to determine the concentrations of 11 metals in the soil of asbestos tailings in Stragari, Serbia, and in the selected plant species that grow on it, to determine the ability of the plant species in accumulation and tolerance of researched metals. Concentrations of elements researched in the soil had this order: Mg> Fe> Ca> Ni> Cr> Mn> Co> Zn> Pb> Cu> Cd. Concentrations of the metals in plants was variable, dependent on the plant species and types of metals, and graded in the order: Mg> Ca> Fe> Ni> Mn> Cr> Zn> Co> Pb> Cu> Cd. The concentrations of Ni and Cr in the investigated soil were above remediation values, as well as the maximum allowable concentration of substances in the soil according to regulation of Republic of Serbia, and the concentration of Cd and Co were above limit values for a given metals in the soil. The metal uptake does not necessarily correlate with metal content in the soil. Metal uptake by plants depends on the bioavailability of the metal in soils, which in turn depends on the retention time of the metal, as well as the interaction with other elements and substances. However, the most Mg, Fe, Mn, Pb, Cd, Co and Cr were found in species Sanguisorba minor, Ca and Cu in Eryngium serbicum, Ni in Alyssum murale, and Zn in Euphorbia cyparissias. In the Euphorbia cyparissias, it were determined the biological absorption coefficients greater than 1 for Zn and Cu, and in the species Eryngium serbicum and Sanguisorba minor greater than 2 for Cu. The results of this study emphasize the tolerance of several metal by species Sanguisorba minor, present the ability of Euphorbia cyparissias in accumulation of Zn and Cu, as well as of Eryngium serbicum and Sanguisorba minor in accumulation of Cu. Obtained results present the momentary picture of investigated locality, open a lot of questions connected with relationships soil/plant, contents of elements in both systems, their interactions and influences and represented the base for further research.

Download Full-text

Measuring Soil Metal Bioavailability in Roadside Soils of Different Ages

Environments ◽

10.3390/environments7100091 ◽

2020 ◽

Vol 7 (10) ◽

pp. 91

Author(s):

Shamali De Silva ◽

Trang Huynh ◽

Andrew S. Ball ◽

Demidu V. Indrapala ◽

Suzie M. Reichman

Keyword(s):

Linear Models ◽

Intrinsic Rate ◽

Strong Relationship ◽

Control Site ◽

Roadside Soil ◽

Metal Bioavailability ◽

Roadside Soils ◽

Metal Concentrations ◽

Total Metal ◽

Soil Metal

Finding a reliable method to predict soil metal bioavailability in aged soil continues to be one of the most important problems in contaminated soil chemistry. To investigate the bioavailability of metals aged in soils, we used roadside soils that had accumulated metals from vehicle emissions over a range of years. We collected topsoil (0–10 cm) samples representing new-, medium- and old-aged roadside soils and control site soil. These soils were studied to compare the ability of the diffusive gradients in thin films technique (DGT), soil water extraction, CaCl2 extraction, total metal concentrations and optimised linear models to predict metal bioavailability in wheat plants. The response time for the release of metals and the effect on metal bioavailability in field aged soils was also studied. The DGT, and extractable metals such as CaCl2 extractable and soil solution metals in soil, were not well correlated with metal concentrations in wheat shoots. In comparison, the strongest relationships with concentrations in wheat shoots were found for Ni and Zn total metal concentrations in soil (e.g., Ni r = 0.750, p = 0.005 and Zn r = 0.833, p = 0.001); the correlations were still low, suggesting that total metal concentrations were also not a robust measure of bioavailability. Optimised linear models incorporating soil physiochemical properties and metal extracts together with road age as measure of exposure time, demonstrated a very strong relationship for Mn R2 = 0.936; Ni R2 = 0.936 and Zn R2 = 0.931. While all the models developed were dependent on total soil metal concentrations, models developed for Mn and Zn clearly demonstrated the effect of road age on metal bioavailability. Therefore, the optimised linear models developed have the potential for robustly predicting bioavailable metal concentrations in field soils where the metals have aged in situ. The intrinsic rate of release of metals increased for Mn (R2 = 0.617, p = 0.002) and decreased for Cd (R2 = 0.456, p = 0.096), Cu (R2 = 0.560, p = 0.083) and Zn (R2 =0.578, p = 0.072). Nickel did not show any relationship between dissociation time (Tc) and road age. Roadside soil pH was likely to be the key parameter controlling metal aging in roadside soil.

Download Full-text