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Influence of electrical conductivity on the phytoremediation of contaminated soils to Cd 2+ and Zn 2+
Maryam Salimi1, Mohammad Mehdi Amin1, Afshin Ebrahimi1, Akbar Ghazifard2, Payam Najafi3
1 Environment Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
2 Department of Geology, School of Earth Sciences, University of Isfahan, Isfahan, Iran
3 Department of Water Engineering, Agricultural Faculty, Islamic Azad University, Khorasgan Branch, Isfaha, Iran
| Date of Web Publication | 28-Mar-2012 |
Correspondence Address:
Mohammad Mehdi Amin
Isfahan University of Medical Sciences, Hezar Jerib Avenue, Isfahan
Iran
© 2012 Salimi et al; This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Aims: This research was conducted to study the effects of the electrical conductivity (EC) of irrigation water and compost on the Cadmium (Cd) and Zinc (Zn) uptake by sunflower, Helianthus annuus. The transfer of Cd and Zn from soils close to the Zn mine, to the sunflower tissues, and the interactions between the two concerned metals, were also investigated.
Materials and Methods: For this purpose, 10% weight/weight from municipal composts was applied to raw soils that were randomly collected from the mine region. Series analyses were also implemented by irrigation water, with EC values in the range of 0, 2, 4, and 6 dS/m.
Results: The maximum uptake rate of Cd, with EC levels of 6 dS/m, in plant samples was 4.82 μg/g for the roots, 6.14 μg/g for the stems, and 5.4 μg/g for the leaves; and the maximum uptake of Zn, in plants irrigated with tap water, was 241 μg/g by the roots, 624 μg/g by the stems, and 229 μg/g by the leaves, respectively.
Conclusions: Results showed that high EC levels of irrigation water increased Cd accumulation and decreased Zn accumulation in the shoots. The presence of high EC levels in irrigation water negatively affected biomass production by plants. Chlorine ion (Cl-) had a positive influence on Cd accumulation in the harvestable parts of the plant. Keywords: Cadmium, phytoremediation, salinity, sunflower, zinc
How to cite this article:
Salimi M, Amin MM, Ebrahimi A, Ghazifard A, Najafi P. Influence of electrical conductivity on the phytoremediation of contaminated soils to Cd 2+ and Zn 2+. Int J Env Health Eng 2012;1:11 |
How to cite this URL:
Salimi M, Amin MM, Ebrahimi A, Ghazifard A, Najafi P. Influence of electrical conductivity on the phytoremediation of contaminated soils to Cd 2+ and Zn 2+. Int J Env Health Eng [serial online] 2012 [cited 2013 Jun 19];1:11. Available from: http://www.ijehe.org/text.asp?2012/1/1/11/94395 |
| Introduction | |  |
The environment may be contaminated with heavy metals that are related to anthropogenic activities such as mining, electroplating, the metal smelting operations, energy and fuel manufacture, severe cultivation, sludge dumping, power transmission, [1],[2] wastewater sludge or municipal composts, fertilizers, emissions from public waste incinerators, and other human activities. [3],[4]
There are several methods for the removal heavy metals from contaminated soils, such as, soil washing, soil structure, and fertility that involve significant engineering costs, and they have an adverse effect on biological activity. [5],[6] Phytoremediation has received increasing recognition, as an environment friendly and low-cost technology. [7],[8] On the other hand, an in situ approach of phytoremediation is attractive, as it offers site restoration and protection of the biological activity, physical structure, and chemical properties of the soil's fractional sanitization. [5],[9],[10] This technology, which is an emerging technology, [11] has a strong potential as a natural, solar energy-driven remediation approach for the treatment of polluted sites, [12] which use green plants and their related rhizospheric microorganisms to remove, degrade, or contain contaminants located in the soil, sediments, groundwater, surface water, and even the atmosphere, to remove metals from the soil or environment. [11],[13],[14]
There are numerous different alternatives for soil phytoremediation [13],[15],[16] such as, phytostabilization and phytoextraction. Phytostabilization consists of the immobilization of metals in the soil or roots, and phytoextraction includes the uptake of contaminants from the soil, which results in the translocation from the roots to the part of the plant above the ground. [13],[15]
The characteristics of the plants that apply for phytoremediation include: Their ability to accumulate the metals intended to be extracted, preferably in the parts above the ground; high tolerance to the metals; fast growth and high biomass yield; cultivation as a crop; and easily harvestable. [17],[18]
Ozkutlu et al., showed that irrigation of crops with saline waters enhanced the mobilization of Cd from the soil and translocation of Cd from the shoots to the grains. [19] Hattori et al., expressed that use of Cl - led to a remarkable enhancement in Cd uptake, in sunflower and kenaf plants. It could be a promising method for the phytoremediation of Cd, in combination with the soil pH adjustment, depending on the tolerance of the plant species to low pH. [20]
The purpose of this study was to determine the effect of salinity on the phytoremediation of Cd and Zn from the contaminant soil.
| Materials and Methods | | |
Experimental design
This study was conducted between 15 June and 17 August, 2010, in a greenhouse at Isfahan (32°39'N, 51°43'E) University of Medical Sciences in Iran. The sampled soil was from the Bama's mine, the third biggest lead and zinc mine of Iran, located in the 20 km interval, at southwest of Isfahan, with a height of 1750 m above sea level, and an average annual rainfall of 140 mm. The municipal solid waste (MSW) compost came from the Isfahan compost plant, after a thorough composting process. The physicochemical characteristics of the compost, sludge, and soil samples that were air-dried and sieved through a 2 mm sieve are shown in [Table 1]. The experimental site consisted of 12 plots that had an inner diameter of 30 cm and a height of 30 cm, with two variables, amendment type, four EC levels, and three replications. Sunflower Helianthus annuus could accumulate metals and had about the same biomass as the Indian mustard. [13] Each pot was filled with 10% W/W municipal compost and dry soils. Tap water was used for irrigation | Table 1: Basic physicochemical characteristics of soil, sludge, and compost
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Characterization of soil and amendments
All chemicals used were purchased from the Merck Company and had analytical purities. The sand, silt, and clay content in the soil were analyzed by the hydrometer method. [21] The organic matter (OM) content in the samples was measured using the Walkley and Black method. [22] The cation exchange capacity (CEC) was determined by NH 4 + saturation at pH 7. [23] Total nitrogen (TN) was determined by the Bremner and Mulvaney method, [24] and total phosphorus (TP) was determined by the Olsen method. [25] Samples were extracted with neutral 1-N ammonium acetate [26] and the potassium concentrations in the extracts were determined by a flame photometer. The soil pH values were determined in a fraction of 1:2 soil-to-water suspensions, with a pH meter model 262, and electrical conductivity (EC) was determined in a fraction of 1:2 soil-to-water suspensions with an EC meter model 644. [27] Heavy metals were determined by the tri-acid digestion method, following the American Public Health Association (APHA) by atomic absorption spectrometry (AAS; Perkin-Elmer 3030 Atomic Absorption Spectrophotometer). [28] For pH and EC measurements, the 1:5 (W/V) municipal compost-to-water to water suspensions were prepared. Next, the pH was measured before filtration, as also the EC on the filtrate.
Plant harvesting
Sampling was started 60 days after sowing (DAS) the plants. Plant harvesting, which paid attention to the roots, took care to extract the plants completely from the soil. Subsequently, all the plant fractions (roots, leaves, and shoots) were carefully washed with deionized water. The fundamental plant growth parameters, such as plant height and fresh and dry biomass of the plant fractions were measured. The dry biomass of the plant fractions were measured after 48 hours at 60°C in an AirForce oven.
Heavy metal content in soil and plant fractions
For determining the heavy metal concentrations, the soil or two amendment samples from each pot were collected, air-dried, screened by means of a 2 mm sieve, and finally oven dried (60°C for 48 hours). Subsequently, these prepared samples were acid-digested and analyzed for Cd and Zn by atomic absorption spectrometry. For plant fractions, the samples were homogenized in particle size by a grinder and their heavy metal content was determined by the dry ashing method. [29]
Data analysis
The data are presented in the text as the average of at least three replicates per treatment. The mean values±standard deviation is reported. The data have been subjected to a one-way analysis of variance (ANOVA), and have been used to examine the effects of the EC levels.
| Results | | |
Soil properties and total contents
The basic physicochemical characteristics of the compost, as amendment and soil, and Zn and Cd fractionation in the studied matrixes, are summarized in [Table 1].
Metal accumulation in plants
Cadmium uptake by the plants
The results in [Table 2] show the Cd uptake by the plants. ANOVA showed that there was a difference between the EC levels and Cd uptake in the roots and leaves (Pvalue <0.05), but not in the stems (Pvalue >0.05). The maximum uptake rate of Cd with an EC level of 6 dS/m in the plants sample was 4.82 μg/g for the roots, 6.14 μg/g for the stems, and 5.4 μg/g for the leaves, respectively. | Table 2: Total Cd (μ g/g dry weight) uptake by root, stem, and leaves of sunflower (Helianthus annuus) in a plant sample that was irrigated with tap water and 2,4, 6 dS/m NaCl solution 60 days after planting; at harvest
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Zinc uptake by the plants. Data regarding the Zn uptake by plants is shown in [Table 3]. The maximum uptake of Zn in plants irrigated with tap water (EC level of 0 dS/m) was, 241 μg/g by the roots, 624 μg/g by the stems, and 229 μg/g by the leaves, respectively. ANOVA showed the difference between the EC levels and the Zn uptake in leaves (Pvalue <0.05), but it not in the roots and stems (Pvalue >0.05). | Table 3: Total Zn (μ g/g dry weight) uptake by roots, stems, and leaves of sunflower (Helianthus annuus L.) in a plant sample that was irrigated with tap water and 2,4, 6 dS/m NaCl solution, 60 days after planting; at harvest
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Growth parameters
Dry weight of the root, stem, and leaves of the plant, and the plant height of the sunflower, grown under non-saline water and saline water irrigation, are shown in [Figure 1], [Figure 2], [Figure 3] and [Figure 4]. The results show that the highest dry weight of the root, stem, and leaves occurs in the sunflower grown under non-saline water irrigation. A significant effect between the EC levels in the dry weight and height of the plant is shown by ANOVA (PValue <0.05). | Figure 1: Variation in the dry weight of the roots of sunflowers in three replicates under different NaCl levels (0, 2, 4, and 6 dS m−1) after 60 DAS. The data are the mean±SD (n=3); Pvalue<0.05
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 | Figure 2: Variation in the dry weight of the stems of sunflowers in three replicates under different NaCl levels (0, 2, 4, and 6 dS m−1) after 60 DAS. The data are the mean±SD (n=3); Pvalue<0.05
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 | Figure 3: Variation in the dry weight of the leaves of sunflowers in three replicates under different NaCl levels (0, 2, 4, and 6 dS m−1) after 60 DAS. The data are the mean±SD (n=3); Pvalue<0.05
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 | Figure 4: Variation in the heights of sunflowers in three replicates under different NaCl levels (0, 2, 4, and 6 dS m−1) after 60 DAS. The data are the mean±SD (n=3); Pvalue<0.05
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Heavy metals in the soil
Cadmium mobility in the soil
Cadmium mobility in the soil with NaCl irrigation and without NaCl irrigation, after 60 DAS, is shown in [Figure 5]. ANOVA has not shown a significant difference between the EC levels and type of treatments in the mobility of cadmium in the soil (Pvalue >0.05).  | Figure 5: Variation levels in the Cd mobility in soil, in three replicates, under different NaCl levels (0, 2, 4, and 6 dS m−1) after 60 DAS. The data are the mean±SD (n=3); Pvalue>0.05
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Zinc mobility in the soil
Results of the zinc mobility in the soil are shown in [Figure 6]. ANOVA did not reveal a significant effect of the mobility of zinc in the different EC levels (Pvalue >0.05). | Figure 6: Variation levels in the Zn mobility in soil, in three replicates, under different NaCl levels (0, 2, 4, and 6 dS m−1) after 60 DAS. The data are the mean±SD (n=3); Pvalue>0.05
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| Discussion | | |
Soil properties and total content
As shown in [Table 1] the texture of the soil was Sandy Loam., and due to the vicinity of the local Zn-mine, high contents of Zn and Cd were found in the raw soil. On account of Low soil pH is a main reason help the uptake of heavy metals. [30]
Metal accumulation in plants
Cadmium uptake by the plants
The results in [Table 2] reveal that Cd uptake rises as the salinity level increases. The obtained results in the current research are in good agreement with the previous ones reported by Ozkutlu, [19] who reported that with rising NaCl, the Cd concentration increased in flag leaves. The study by Khoshgoftar [31] showed that with increasing salinity, the Cd concentration in the grain shoots increased proportionally with the level of NaCl. With an enhanced NaCl level in irrigation water, the Cl - concentration in the soil and the Cd uptake by plants increased. The Cl - ion formed complex ions with Cd to form CdCl + , CdCl3 - , and CaCl4 - . The application of Cl - might dissolve the adsorbed soil Cd to form complex ions. It was assumed that the Cd dissolved by Cl - was absorbed by sunflowers and moved to the leaves through the xylem, in the form of complex ions, and accumulated there. [20] The results of this experiment revealed that the absorption of cadmium in plants irrigated with saline water was more than in plants irrigated with non-saline water. CdCln 2-n complexes could dominate the Cd solution chemistry and take it up directly across the plasma membrane, thus increasing the phytoavailability of Cd to the plant and enhancing the root uptake of Cd. [32] The main factor of Cd uptake enhancement was the formation of the Cd-Cl complex. [33]
Zinc uptake by the plants
Data regarding Zn uptake exhibited that as the salinity increased, the concentration of Zn in the plant decreased [Table 3]. The results from this investigation showed that Zn uptake by the plant decreased with increasing Cd uptake. Therefore, our findings were very much in line with the results obtained by researchers like Khoshgoftar, [31] Ozkutlu, [19] and Bunluesin, [34] who expressed that increasing the absorption of cadmium, caused a decline in the absorption of zinc, in plants. There was a strong competition between these two metals for the same membrane-transporters. [35] A study showed that the effects of Zn on plant Cd uptake relied on the concentration of Cd and Zn, plant variety, and type of plant tissue. [34] The analysis that was done by Nan et al. showed the Cd-Zn interaction mechanism, and they concluded that the effects of the two metals were synergistic to each other in the field conditions. [36]
Growth parameters
The data, in general, showed that the dry weight of plants and the plant height of sunflower grown under saline water irrigation significantly decreased, as compared with those grown under non-saline water irrigation [Figure 1], [Figure 2], [Figure 3] and [Figure 4]. The results in the present study were in agreement with those reported by Mohamedin et al., [37] who stated that salinity stress caused a significant reduction in the growth parameters studied and also the macro- and micronutrient concentrations in plants. [Figure 1], [Figure 2], [Figure 3] and [Figure 4] reveal a considerable decrease in the dry weight of roots, stems, leaves, and heights of sunflower, under different NaCl levels. This was because of the effects of salinity on the reduction of water absorption and metabolic activities of the plants. The presence of high concentrations of the metals in the plant tissues and high salt concentrations negatively affected the plant health and growth reduction. [38]
Heavy metals in the soil
Cadmium mobility in the soil
Although ANOVA did not show any significant effect on the EC of cadmium mobility in the soil, the result pertaining to the Cd concentration in the soil, after 60 DAS, showed that with NaCl irrigation, the mobility of Cd in the soil was more than in the soil without NaCl irrigation [Figure 5], and by increasing the NaCl levels in the irrigation water, the mobility of heavy metals in the soil increased. Soil mobility of cadmium depended on different characteristics of the soil, such as, pH, organic matter, cation exchange capacity, clay content, chloride level, and cadmium and zinc concentrations. [39] Saline water enhanced the mobility of heavy metals. [40]
Zinc mobility in the soil
With increasing EC levels, the metal mobility in the soil increased However, ANOVA did not show any significant effect of the EC levels on Zinc mobility in the soil [Figure 6].
| Conclusions | | |
By application of NaCl in the shoots, the Cd concentration in this zone of the plants was increased. On account of the high mobility of Cd with NaCl, the results presented in this article showed that, remobilization of the Cd deposited in the stems or other plant tissues were promoted in the presence of Cl, by the formation of mobile CdCln 2-n complexes. On the other hand, our data indicated that irrigation of sunflower with saline water containing high NaCl concentrations could not only mobilize Cd from the soil, but also increase the translocation of Cd from the roots to the shoots. The effect of NaCl on the other hand was significant, and proportionally decreased Zn accumulation in the shoots.
| Acknowledgment | | |
This paper is the result of MSc. approved thesis, Research Project # 389067, in Isfahan University of Medical Sciences (IUMS). The authors wish to acknowledge the financial support provided by the School of Health and the Environment Research Center, IUMS.
| References | | |
| 1. | Wang J, Chen C. Biosorbents for heavy metals removal and their future. Biotechnol Adv 2009;27:195-226. 
|
| 2. | Chehregani A, Noori M, Yazdi HL. Phytoremediation of heavy-metal-polluted soils: Screening for new accumulator plants in Angouran mine (Iran) and evaluation of removal ability. Ecotoxicol Environ Saf 2009;72:1349-53.
|
| 3. | Sasmaz A, Sasmaz M. The phytoremediation potential for strontium of indigenous plants growing in a mining area. Environ Exp Bot 2009;67:139-44.
|
| 4. | Linger P, Müssig J, Fischer H, Kobert J. Industrial hemp (Cannabis sativa L.) growing on heavy metal contaminated soil: Fibre quality and phytoremediation potential. Ind Crops Prod 2002;16:33-42.
|
| 5. | Pulford ID, Watson C. Phytoremediation of heavy metal-contaminated land by trees-a review. Environ Int 2003;29:529-40.
|
| 6. | Khan AG. Role of soil microbes in the rhizospheres of plants growing on trace metal contaminated soils in phytoremediation. J Trace Elem Med Biol 2005;18:355-64.
|
| 7. | Liphadzi MS, Kirkham MB. Availability and plant uptake of heavy metals in EDTA-assisted phytoremediation of soil and composted biosolids. S Afr J Botany 2006;72:391-7.
|
| 8. | Bañuelos GS. Phyto-products may be essential for sustainability and implementation of phytoremediation. Environ Pollut 2006;144:19-23.
|
| 9. | Mora APd, Ortega-Calvo JJ, Cabrera F, Madejón E. Changes in enzyme activities and microbial biomass after "in situ" remediation of a heavy metal-contaminated soil. Appl Soil Ecol 2005;28:125-37.
|
| 10. | Clemente R, Almela C, Bernal MP. A remediation strategy based on active phytoremediation followed by natural attenuation in a soil contaminated by pyrite waste. Environ Pollut 2006;143:397-406.
|
| 11. | Ouyang Y. Phytoremediation: Modeling plant uptake and contaminant transport in the soil-plant-atmosphere continuum. J Hydrol 2002;266:66-82.
|
| 12. | Marchiol L, Fellet G, Perosa D, Zerbi G. Removal of trace metals by Sorghum bicolor and Helianthus annuus in a site polluted by industrial wastes: A field experience. Plant Physiol Biochem 2007;45:379-87.
|
| 13. | Pivetz BE, Ok Nrmrla. Ground Water Issue: Phytoremediation of Contaminated Soil and Ground Water at Hazardous Waste Sites. EPA/540/S-01/500;2001.
|
| 14. | Agamuthu P, Abioye OP, Aziz AA. Phytoremediation of soil contaminated with used lubricating oil using Jatropha curcas. J Hazard Mater 2010;179:891-4.
|
| 15. | Doumett S, Lamperi L, Checchini L, Azzarello E, Mugnai S, Mancuso S, et al. Heavy metal distribution between contaminated soil and Paulownia tomentosa, in a pilot-scale assisted phytoremediation study: Influence of different complexing agents. Chemosphere 2008;72:1481-90.
|
| 16. | Punamiya P, Datta R, Sarkar D, Barber S, Patel M, Das P. Symbiotic role of Glomus mosseae in phytoextraction of lead in vetiver grass [Chrysopogon zizanioides (L.)]. J Hazard Mater 2010;177:465-74.
|
| 17. | Chaney R, Li Y, Angle J, Baker A, Reeves R, Brown S, et al. Improving metal hyperaccumulator wild plants to develop commercial phytoextraction systems: Approaches and progress. Phytoremediation contaminated soil and water CRC Press, Boca Raton, FL. 2000:129-58.
|
| 18. | Fellet G, Marchiol L, Perosa D, Zerbi G. The application of phytoremediation technology in a soil contaminated by pyrite cinders. Ecol Eng 2007;31:207-14.
|
| 19. | Ozkutlu F, Ozturk L, Erdem H, McLaughlin M, Cakmak I. Leaf-applied sodium chloride promotes cadmium accumulation in durum wheat grain. Plant Soil 2007;290:323-31.
|
| 20. | Hattori H, Kuniyasu K, Chiba K, Chino M. Effect of chloride application and low soil pH on cadmium uptake from soil by plants. Soil Sci Plant Nutr 2006;52:89-94.
|
| 21. | Gee GW, Bauder JW. Particle-size analysis. In: Klute A, editor. Methods of Soil Analysis, Part 1. (2 nd edition; Agronomy No 9). Madison, WI: Am Soc Agron; 1986. p. 404-9.
|
| 22. | Walkley A, Black IA. An examination of the Degtjareff method for determining soil organic matter, and a proposed modification of the chromic acid titration method. Soil Sci 1934;37:29.
|
| 23. | Rhodes JD. Cation exchange capacity. In: Page, AL, Miller, RH, Keeney, DR (Eds), Methods of Soil Analysis Part 2 (2 nd edition; Agron Monogr No 9). Madison, WI: ASA and SSSA; 1982. p. 149-58.
|
| 24. | Bremner and Mulvaney JMBaCSM, Nitrogen - total. In: Page AL, Miller RH, Keaney DR, editors. Methods of Soil Analysis, Part 2. Chemical and Microbiological Properties (2 nd edition), Agronomy 9. Madison, WI: American Society of Agronomy; 1982. p. 595-624.
|
| 25. | Olsen S, Sommers L. Phosphorus in methods of soil analysis Part 2. Chemical and microbiological properties Agronomy Monograph. American Society of Agronomy-Soil Science Society of America; 1982. p. 421-2.
|
| 26. | Knudsen D, Peterson GA, Pratt PF. Lithium, sodium, and potassium. In: Page AL, Miller RH, Keeney DR, editors. Methods of soil analysis, part 2. Chemical and microbiological properties. Madison, Wisconsin, USA: American Society of Agronomy; 1982. p. 225-46.
|
| 27. | Fornes F, García-de-la-Fuente R, Belda RM, Abad M. 'Alperujo' compost amendment of contaminated calcareous and acidic soils: Effects on growth and trace element uptake by five Brassica species. Bioresour Technol 2009;100:3982-90.
|
| 28. | Eaton AD, Franson MA. Standard methods for the examination of water and wastewater: Amer Public Health Assn; 2005.
|
| 29. | Tüzen M. Determination of heavy metals in soil, mushroom and plant samples by atomic absorption spectrometry. Microchem J 2003;74:289-97.
|
| 30. | Moustakas N, Akoumianaki-Ioannidou A, Barouchas P. The effects of cadmium and zinc interactions on the concentration of cadmium and zinc in pot marigold (Calendula officinalis L.).
|
| 31. | Khoshgoftar A, Karimian H, Kalbasi N, van der Zee M, Parker S. Salinity and zinc application effects on phytoavailability of cadmium and zinc. Soil Sci Soc Am J 2004;68:1885.
|
| 32. | Grant C, Buckley W, Bailey L, Selles F. Cadmium accumulation in crops. Can J Plant Sci 1998;78:1-18.
|
| 33. | Wei K, Shamsi IH, Zhang G. Synergistic interaction of NaCl and Cd on growth and photosynthetic parameters in soybean genotypes differing in salinity tolerance. J Zhejiang Univ Sci B 2007;8:266-71.
|
| 34. | Bunluesin S, Pokethitiyook P, Lanza GR, Tyson JF, Kruatrachue M, Xing B, et al. Influences of cadmium and zinc interaction and humic acid on metal accumulation in Ceratophyllum demersum. Water Air Soil Pollut 2007;180:225-35.
|
| 35. | Cherif J, Mediouni C, Ammar WB, Jemal F. Interactions of zinc and cadmium toxicity in their effects on growth and in antioxidative systems in tomato plants (Solarium lycopersicum). J Environ Sci 2011;23:837-44.
|
| 36. | Nan Z, Li J, Zhang J, Cheng G. Cadmium and zinc interactions and their transfer in soil-crop system under actual field conditions. Sci Total Environ 2002;285:187-95.
|
| 37. | Mohamedin A, El-Kader AA, Badran NM. Response of sunflower (Helianthus annuus L.) to plants salt stress under different water table depths. J Appl Sci Res 2006;2:1175.
|
| 38. | Katerji N, Van Hoorn J, Hamdy A, Karam F, Mastrorilli M. Effect of salinity on emergence and on water stress and early seedling growth of sunflower and maize. Agric Water Manage 1994;26:81-91.
|
| 39. | Simon L. Cadmium accumulation and distribution in sunflower plant. J Plant Nutr 1998;21:341-52.
|
| 40. | Wahla IH, Kirkham MB. Heavy metal displacement in salt-water-irrigated soil during phytoremediation. Environ Pollut 2008;155:271-83.
|
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3]
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