Effects of soil amendments on antimony uptake by wheat
Irina Shtangeeva, Matti Niemelä & Paavo Perämäki
Journal of Soils and Sediments ISSN 1439-0108 Volume 14 Number 4 J Soils Sediments (2014) 14:679-686 DOI 10.1007/s11368-013-0761-8
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Author's personal copy J Soils Sediments (2014) 14:679–686 DOI 10.1007/s11368-013-0761-8
POTENTIALLY HARMFUL ELEMENTS IN SOIL-PLANT INTERACTIONS
Effects of soil amendments on antimony uptake by wheat Irina Shtangeeva & Matti Niemelä & Paavo Perämäki
Received: 19 April 2013 / Accepted: 20 July 2013 / Published online: 13 August 2013 # Springer-Verlag Berlin Heidelberg 2013
Abstract Purpose Environmental chemistry of antimony (Sb) is still largely unknown. Many questions remain about its availability to plants and effects of fertilizers on mobility of Sb in the rhizosphere soil. In this work, we focused on the following problems: (1) uptake of Sb by wheat seedlings grown in soil enriched with this metalloid and (2) impact of soil amendments on the plant growth, Sb uptake from soil, and its transfer from roots to upper plant parts. Materials and methods To obtain further information on the possible transfer of Sb into plants, greenhouse pot experiments were carried out. Soil was spiked with 15 mg kg−1 of Sb and amended with either chicken manure or natural growth stimulator Energen. Wheat Triticum aestivum L. seedlings were grown in the soil during 17 days. Plants together with rhizosphere soil were collected several times in the course of the experiment. The ICP-OES and ICP-MS techniques were applied to determine the concentrations of macro- and trace elements in the plant and soil material. Results and discussion Growth of wheat seedlings in Sbspiked soil resulted in Sb accumulation in roots and leaves of the plants. Energen and especially chicken manure were capable of stimulating transfer of Sb to more mobile and, as a consequence, more available to the plants form, thus enhancing both uptake of Sb from soil and its transfer from roots to upper plant parts. The accumulation of Sb by plants led to a decrease of Sb concentration in the rhizosphere soil with time, and the most significant decrease was observed after amendment of soil with fertilizers.
Responsible editor: Jaume Bech I. Shtangeeva (*) Chemical Department, St. Petersburg University, Universitetskaya nab. 7/9, 199034 St. Petersburg, Russia e-mail:
[email protected] M. Niemelä : P. Perämäki Department of Chemistry, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland
Conclusions Fertilizers may be used to increase phytoextraction of Sb and its removal from contaminated soils. However, such an amendment of soil should be done with caution in order to exclude or at least reduce the negative effects on plants. Keywords Antimony . Fertilizers . Phytoextraction . Wheat seedlings
1 Introduction Antimony (Sb) is a toxic and potentially carcinogenic trace element (Cooper and Harrison 2009). Natural concentrations of Sb in the environment are low. Background concentrations of Sb in soils are between 0.3 and 8.6 mg kg−1 (Salminen 2005; He 2007; Wilson et al. 2010; Kelly et al. 2012). Recent reports, however, indicate that Sb is a global pollutant (Smichowski 2007; Pan et al. 2011). Antimony world production peaked at 203,500 t of Sb in 2011, driven by continued growth in consumption in flame retardants and lead-acid batteries (Baylis 2012). Growth in Sb consumption has been continued through 2012. Such a significant use of Sb led to increasing environmental pollution by this metalloid (Jia et al. 2012). Meanwhile, the effects of elevated soil Sb concentration on the plant growth and Sb uptake by plants have only recently attracted attention of researchers (Murciego et al. 2007; Filella et al. 2009; Tschan et al. 2010; Qi et al. 2011; Wan et al. 2013). At present, a considerable body of data on distribution of Sb in soils and plants near highly contaminated mining areas is collected. However, until now, much less attention has been paid to distribution of Sb in the plants grown in uncontaminated soils and effects of soil fertilization on the availability of Sb to plants (Kilgour et al. 2007; Conesa et al. 2010, 2012; Wilson et al. 2013). Commercial fertilizers play an important role in the improvement of soil fertility and crop production. The improvement of the plant growth and root density can also influence on the uptake of nutrients (in general, the more biomass the
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plants have, the more they can accumulate different elements, since the uptake of elements is a function of the overall biomass). Fertilizers can effectively and specifically increase solubility and, therefore, bioaccumulation of not only essential plant nutrients, but also toxic metals (Bolan and Duraisamy 2003; Shtangeeva et al. 2008). The effects observed as a result of soil fertilization may be rather different and depend on physicochemical parameters of soil, type of applied fertilizer, and species of plants growing in the soil (Willems and Nieuwstadt 1996). The objectives of this research were (1) to study the uptake of Sb by wheat seedlings grown in soil enriched with this metalloid and (2) to compare the effects of soil amendment with two different fertilizers on the plant growth, Sb uptake from soil, and its transfer from roots to upper plant parts.
2 Materials and methods 2.1 Experimental design The effects of chicken manure and Energen (natural stimulator of the plant growth and development; it contains humic and silicic acids and bioavailable potassium) on the possible transfer of Sb from soil to plants were tested in greenhouse conditions. Seeds of wheat Triticum aestivum L. were germinated on wet filter paper for 5 days, and then uniformed germinated seedlings were transferred to ceramic pots (20 cm top diameter) filled with soil (7 kg of soil in a pot). The soil was classified as Ferric Podzol with sandy loam texture. There were ∼20 seedlings in a pot. The seedlings were grown in the pots for 17 days. Half of the plants was grown in Sb-free soil, and the other half was grown in soil spiked with 15 mg kg−1 of Sb as Sb(OH)2NO3. Each set (both Sb-free and Sb-spiked soils) was divided into three parts. To the first part of pots, 100 mg kg−1 of dry chicken manure was added, and to the second part of pots, 20 mg kg−1 of Energen was added. The doses are recommended by the fertilizer's producers for this type of soil and this plant species. The last part of pots was kept as a control. In total, there were six treatments, including control. The experiments had a randomized block design with three replications. During the experiment, the soil pH value was 6.3±0.2. Soil water content was measured in the beginning of the experiment by soil moisture sensor 10HS (Decagon Devices, Russia). During the experiment, the soil water content was checked every day. To maintain the mean level of soil moisture (25%), the pots were watered daily by adding 300 mL of water per pot. Before seedlings were transferred to pots, soil samples (initial soil) were taken from all pots. Plants (together with the rhizosphere soil) were collected within 1, 6, 12, and 17 days after the transfer of seedlings to the soil. At the end of the experiment, soil was also taken from the bottom of the pots
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to check for possible leaching of Sb to deeper soil layers. After sampling, soil was air dried up to constant weight. Plants were carefully washed by deionized water just after sampling, separated into roots and leaves, and also dried under room temperature to constant weight. 2.2 Analysis of plant and soil samples A Thermo Elemental X7 quadrupole ICP-MS, equipped with a standard low-volume glass impact bed spray chamber (Peltier cooled at +3 °C), a concentric glass nebulizer, and a Cetac ASX-500 autosampler, was used in the analysis of plant (27Al, 137Ba, 59Co, 121Sb, and 88Sr) and soil (27Al, 137Ba, 59 Co, 121Sb, and 88Sr) samples. The instrumental parameters were as follows: RF power 1.30–1.35 kW, nebulizer gas flow 0.93–0.98 L min−1, auxiliary gas flow 0.85–0.95 L min−1, and cooling gas flow 13.5 L min−1. The ion lens settings, gas flow rates, RF power, and torch position of the instrument were optimized daily in order to obtain the maximum 115 In count rate. The analytical parameters of ICP-MS were as follows: acquisition mode: peak jumping and simultaneous pulse count/analog detector system; dwell time/ channels per mass: 10 ms/1 channel (100 ms/3 channels in 121Sb determinations); number of repeats/sample: three; and sweeps: 100. In addition, a PerkinElmer Optima 5300 DV ICP-OES, which allows either axial or radial mode of viewing of the plasma, was used in the determination of Ca, Fe, K, Mg, Mn, Na, and P concentrations from the plant samples and in the determination of Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, P, Sr, and Zn concentrations from the soil samples. A PerkinElmer Zeeman/3030 atomic absorption spectrometer, equipped with a Zeeman effect background correction system, a HGA-600 graphite furnace, and an AS-60 autosampler, was used in the determination of Cr, Cu, and Fe from the plant samples. Digestion methods used for the plant and soil samples were based on the Environmental Protection Agency procedure 3052 (USEPA Method 3052 1996). For digestion of plant samples, each sample was weighed into the microwave digestion vessel (XP-1500 plus high-pressure Teflon® TFM vessels, CEM Corp.), then 9 ml of concentrated HNO3 was added, the vessels were closed, and the samples were heated in the CEM MARS 5X (CEM Corp.) microwave oven (program, heating for 10 min to 180 °C and holding at 180 °C for 9.30 min). After that, samples were diluted to 25 ml with ultrapure water. Soil samples were weighed into the microwave digestion vessels, then 9 ml of concentrated HNO3, 2 ml of concentrated HCl, and 2 ml of concentrated HF were added; the vessels were closed, and the samples were heated in the microwave oven (program, heating for 10 min to 180 °C and holding at 180 °C for 9.30 min). After the program was completed, the vessels were cooled down to room temperature
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and vented carefully. Then, 30 ml of H3BO3 (4% w/v) was added, and the digestion was continued in the microwave oven (program, heating for 15 min to 170 °C and holding at 170 °C for 10 min). Then, the samples were diluted to 100 ml with ultrapure water. The accuracy of the measured concentrations was verified by determining the same elements in the certified reference materials (CRMs), tomato leaves 1573 and 1573a (National Institute for Science and Technology, USA), and marine sediment reference material PACS-2 (National Research Council, Canada). The results of the analysis of the CRMs showed a good agreement with certificated values (differences did not exceed 5–7%).
2.3 Statistical analysis For multivariate statistical analysis, Statistica for Windows 6.0 software packages were used. This included calculation of mean concentrations of elements and analysis of variances to estimate statistically significant differences between groups of samples. In addition, correlation and cluster analyses were applied to the datasets to classify the plants according to their ability to uptake Sb and other macro- and micronutrients.
3 Results and discussion 3.1 Antimony concentrations in soil and in different plant parts and effects of Sb on the biomass of wheat seedlings Concentrations of Sb and other macro- and trace elements in the rhizosphere soil and in roots and leaves of wheat seedlings are presented in Tables 1 and 2. An increase of Sb in soil resulted in its accumulation in roots and leaves of the seedlings grown in the Sb-spiked soil. The differences between Sb concentrations in the plants grown in control soil and in soil spiked with Sb were statistically significant with one exception; the increase of Sb concentration in leaves of the plants grown in Sb-spiked non-fertilized soil was registered, but the difference with control was statistically insignificant. Figure 1 illustrates variations in the biomass of wheat seedlings grown in control (Sb-free) soil and in soil spiked with Sb (without additional treatments and after applying to soil chicken manure and Energen). There were no significant differences between biomasses of the seedlings grown in control soil and in soil spiked with Sb, but compared to the biomasses of the seedlings grown in control fertilized soil, biomasses of the seedlings grown in soil enriched with Sb and amended with both chicken manure and Energen slightly decreased by the end of the experiment.
Table 1 Mean concentrations (± standard deviation) of elements in soil (*g kg−1; **mg kg−1). In parenthesis are number of samples analyzed Element
1 (4)
2 (3)
3 (3)
4 (4)
5 (4)
6 (4)
Na*
6.0±0.3
6.0±0.2
6.9±0.5
6.8±0.5b
5.8±0.9
6.2±0.3
Mg* Al* P* K* Ca* Mn* Fe* Zn* Sr* Ba* Cr** Co** Ni** Sb**
9.95±2.11 39.2±3.4 2.70±0.21 11.7±0.7 90±8 0.68±0.10 39±7 0.052±0.014 0.26±0.01 0.88±0.18 33±4 9.4±1.2 51±13 0.90±0.03
8.74±0.04 37.0±0.2 2.42±0.02 10.7±0.1 78±2 0.58±0.02 33±1 0.048±0.003 0.26±0.01 0.82±0.05 30±1 8.6±0.3 55±4 0.80±0.01a
9.07±1.12 40.4±4.4 2.73±0.20 12.2±1.0 73±7 0.64±0.07 35±4 0.049±0.006 0.26±0.03 0.80±0.08 33±3 8.9±1.1 54±4 0.78±0.10
8.17±1.14 39.0±3.6 2.41±0.43 11.2±1.6 72±13 0.55±0.18 34±6 0.043±0.014 0.25±0.02 0.81±0.14 30±3 8.5±1.2 52±32 6.77±1.08b
7.28±0.53c 28.9±7.8 1.98±0.46c 10.5±0.6 77±18 0.47±0.03c 29±2 0.037±0.003c 0.25±0.03 0.76±0.07 27±1c 7.8±0.9 62±9 5.24±2.27c
9.04±0.84 38.5±2.2 2.60±0.32 11.4±0.3 71±9 0.61±0.02 35±2 0.054±0.004 0.25±0.03 0.77±0.04 31±3 9.2±1.1 56±7 7.27±1.39d
1 Control, 2 soil was amended with Energen, 3 soil was amended with chicken manure, 4 non-fertilized soil was spiked with 15 mg kg−1 of Sb, 5 soil was spiked with Sb and amended with Energen, and 6 soil was spiked with Sb and amended with chicken manure a
Differences between control soil and soil amended with Energen are statistically significant (P
