Methods to Quantify Nickel in Soils and Plant Tissues

Abstract

in comparison with other micronutrients, the levels of nickel (Ni) available in soils and plant tissues are very low, making quantification very difficult. The objective of this paper is to present optimized determination methods of Ni availability in soils by extractants and total content in plant tissues for routine commercial laboratory analyses. Samples of natural and agricultural soils were processed and analyzed by Mehlich-1 extraction and by DTPA. To quantify Ni in the plant tissues, samples were digested with nitric acid in a closed system in a microwave oven. the measurement was performed by inductively coupled plasma/optical emission spectrometry (ICP-OES). There was a positive and significant correlation between the levels of available Ni in the soils subjected to Mehlich-1 and DTPA extraction, while for plant tissue samples the Ni levels recovered were high and similar to the reference materials. The availability of Ni in some of the natural soil and plant tissue samples were lower than the limits of quantification. Concentrations of this micronutrient were higher in the soil samples in which Ni had been applied. Nickel concentration differed in the plant parts analyzed, with highest levels in the grains of soybean. the grain, in comparison with the shoot and leaf concentrations, were better correlated with the soil available levels for both extractants. The methods described in this article were efficient in quantifying Ni and can be used for routine laboratory analysis of soils and plant tissues.

Growth of tropical grasses in Oxisol contaminated by nickel

“…The available levels for plants rather than total levels (Rodak et al, 2015). Therefore, there are no ranges and critical values in agricultural or natural soils regarding available Ni concentrations (Mehlich-1 and DTPA), demonstrating the need to define them as in the present work (Table 4).…”

“…Although Ni is an essential element for plants (López and Magnitski, 2011;Fabiano et al, 2015), high levels of this metal in the environment can cause phytotoxicity (Kovácik et al, 2009) and even reach the animal and human food chain (Rodak et al, 2015). In general, critical toxicity levels are 10 mg kg -1 DM in sensitive species, 50 mg kg 1 DM in moderately tolerant species, 100 mg kg -1 DM in tolerant species (Yusuf et al, 2011;Hussain et al, 2013;Matraszek et al, 2016), and 1000 mg kg -1 DM in Ni hyperaccumulator plants, such as the Alyssum and Thlaspi species (Yusuf et al, 2011;Leitenmaier and Küpper, 2013;Matraszek et al, 2016).…”

“…There have been several solutions to extract bioavailable concentrations of heavy metals in soil, such as diethylenetriaminepentaacetic acid (DTPA), Mehlich-1, and acid mixture (Rodak et al, 2015); some of these have been used in laboratories to evaluate the availability of various cationic micronutrients. The United States Environmental Protection Agency recommends determining the pseudo total present in the sample concentration (USEPA, 2007) to monitor soil pollution by heavy metals.…”

“…For this, strong acids have been used that are not part of the routine chemical soil analysis for fertility purposes; they do not always extract concentrations of elements correlated with levels absorbed by plants. Correlations between soil Ni concentration extracted by several extractors and the concentration accumulated by some plants have defined the most efficient extractors to predict the phytoavailability of this element (Berton et al, 2006;Chang et al, 2014;Rodak et al, 2015).…”

Multielemental analyses of Lonomia obliqua (Lepidoptera, Saturniidae) caterpillar using EDXRF and INAA techniques

“…It can be added to the soil by industrial and urban waste disposal. One of these residues is the sewage sludge a material rich in nutrients and metals for plants . Besides, Ti can be a residue generated in the production of phosphoric acid (phosphate rocks may contain up to 30% Ti) fertilizer widely used in Brazil.…”