اثر ماده آلی بر توزیع شکل‌های شیمیایی کادمیم در خاک در محیط ریشه ذرت

نوع مقاله : مقالات پژوهشی

نویسندگان

دانشگاه فردوسی مشهد

چکیده

برای ارزیابی خطرآفرینی آلودگی فلزات سنگین در خاک، آگاهی از زیست فراهمی فلزات بسیار مهم است که خود به توزیع شکل‌های شیمیایی آن‌ها در خاک بستگی دارد. به منظور بررسی اثر ماده آلی (کود گاوی) و نحوه تأثیر فعالیت ریشه و ترشحات آن بر توزیع شکل‌های شیمیایی فلز کادمیم، آزمایشی به صورت گلخانه‌ای بر روی خاک آلوده به کادمیم در سیستم رایزوباکس انجام گرفت. این آزمایش به صورت فاکتوریل در قالب طرح کاملا تصادفی با 2 سطح ماده آلی (حضور و عدم حضور ماده آلی) و 3 ناحیه با فاصله از ریشه و با 3 تکرار اجراء شد. به منظور تعیین شکل‌های شیمیایی کادمیم از روش عصاره‌گیری متوالی تسیر استفاده شد. نتایج نشان داد که افزودن ماده آلی به خاک بر تغییرات هیچ یک از شکل‌های شیمیایی کادمیم در خاک جز فرم زیست‌فراهم بطور معنی‌داری مؤثر نبوده است اما موجب افزایش معنی‌دار pH، CEC و مقدار کربن آلی در خاک شد. بنابراین می‌توان گفت کاهش معنی‌دار فرم زیست‌فراهم کادمیم در اثر افزودن ماده آلی به خاک به علت تغییر ویژگی‌های خاک بوده است. بر اساس نتایج، افزودن کود گاوی به خاک بیشترین تأثیر را بر فرم کربناتی کادمیم دارد. همچنین غلظت کادمیم در ریشه گیاه ذرت در شرایط حضور و عدم حضور ماده آلی بطور معنی‌داری بیشتر از اندام ‌هوایی بوده است. این امر نشان می‌دهد که کادمیم تمایل بیشتری برای تجمع در ریشه گیاه در مقایسه با اندام ‌هوایی داشته است.

کلیدواژه‌ها


عنوان مقاله [English]

Effect of Organic Matter on Distribution of Chemical Forms of Cadmium in Soil in Corn Rhizosphere

نویسندگان [English]

  • faeze lotfi
  • amir fotovat
  • reza khorasani
  • Mahdi Bahraini
Ferdowsi University of Mashhad
چکیده [English]

Introduction: The pollution of soils by heavy metals due to human activities poses a serious concern for human and environmental health. In order to evaluate the risks of heavy metal contamination such as cadmium in soil, it is necessary to understand its bioavailability which depends on its chemical forms in the soil. According to Tessier (1979), heavy metals can be found in various chemical forms in soil including exchangeable, bound to carbonates, bound to iron and manganese oxides and bound to organic matter and residual. These fractions significantly influence the cadmium mobility and bioavailability. Distribution of metals in chemical forms in soil depends on soil pH, amount of organic matter, oxidation-reduction potential and ionic strength. Root exudation, soil texture, cation exchangeable capacity and amount of calcium carbonate may also impact chemical forms of cadmium. Many studies have showed that plant root may affect the chemistry of heavy metals in soil root zone. The objective of this study was to evaluate the effect of organic matter on the distribution of cadmium in corn root media.
Materials and Methods: To investigate the effect of organic matter (cow manure) and root activity on chemical forms of cadmium, a greenhouse experiment was conducted using rhizobox. The contaminated soil sample used in the study was collected from Zanjan. This greenhouse experiment was conducted in a factorial design, with 2 replications, two levels of organic matter (0 and 1.5%) and three zones classified based on their distance from root. The soil samples were air dried and crushed to pass through a 2-mm sieve. The cultivation was conducted using a rhizobox. The rhizobox consisted of three parts: 1.central compartment (rhizosphere), 2.close to rhizosphere, and 3. soil bulk. Soil samples were mixed with fertilizer and packed in rhizobox. Eight pre-germinated maize seedlings were transferred to the central compartment and five days after germination, thinned to four plants. Ten weeks after planting, corn plants were harvested for analysis. The compartments of rhizobox were separated. The collected plant samples (root and shoot) were rinsed with deionized water and oven-dried at 70 °C. Soil samples were also measured for pH, CEC and total organic carbon. The chemical forms of cadmium in the soil and plant samples were identified by the sequential extraction procedure proposed by Tessier (1979). Bioavailable cadmium in soil was also extracted by DTPA-TEA.
Results and Discussion: Results showed that the highest amount of soil cadmium was found in carbonate fraction. Adding organic matter increased the soil pH, CEC and organic carbon amount, whereas none of chemical forms of cadmium were significantly affected by adding organic matter. Bioavailability of cadmium, however, decreased by adding organic matter to soil, It can be therefore concluded that increment in cadmium uptake due to increased organic matter led to decreased cadmium bioavailability. The exchangeable cadmium was negatively correlated to soil organic carbon, while bioavailable cadmium was negatively correlated to soil pH, CEC and amount of soil organic carbon. Moreover, our results indicated that the fractions of cadmium were not significantly affected by distance from the root. Moreover, adding organic matter insignificantly increased concentration of cadmium in shoots, roots and total plants.
Conclusion: In this study, among different chemical forms of cadmium, only bioavailable cadmium was significantly affected by adding organic matter to soil. Additionally, soil pH, CEC and organic carbon were significantly increased by adding organic matter. These results indicate that addition of organic matter to soil may indirectly influence chemical forms of cadmium through impacting soil properties (soil pH, CEC and organic carbon). The addition of organic matter had the most influence on carbonate fraction of cadmium which may be potentially available to plant. It seems that addition of organic matter (cow manure) may result in increase of cadmium concentration in plant. Therefore, it can be concluded that addition of cow manure to calcareous soils with neutral to slightly alkaline pH may lead to increased cadmium uptake by the plant (corn) and reduced soil cadmium concentration.

کلیدواژه‌ها [English]

  • Bioavailability
  • Cadmium
  • Fractionation
  • Organic matter
  • Rhizobox
1- Akkajit P., and Tongcumpou C. 2010. Fractionation of metals in cadmium contaminated soil: Relation and effect on bioavailable cadmium. Geoderma, 156(3), 126-132.
2- Alavi H., Motlagh M. B., and Dordipour E. 2012. Determination of chemical forms of copper and their relationships with plant responses and soil properties in some soils of Golestan Province. Water And Soil Conservation, 19(3), 20. (in Persian with English abstract).
3- Azimzadeh Y., Shariatmadari H., and Shirvani M. 2013a. Changes in chemical forms and bioavailability of zinc by distance from rhizosphere of single and mixed culture. Soil Applied Reaserch, 1(1), 12. (in Persian with English abstract).
4- Azimzadeh Y., Shariatmadari H., and Shirvani M. 2013b. Remediation of some soil heavy metals by corn and canola in single and mixed culture system. Water and Soil, 27(2), 9. (in Persian with English abstract).
5- Azimzadeh Y., Shirvani M., and Shariatmadari H. 2013c. Effect of green manure on chemical forms of some heavy metalsin soil by distance from rhizosphere of corn. Soil Applied Reaserch, 2(2), 20. (in Persian with English abstract).
6- Baghaie A. H., Khoshgoftarmanesh A. H., and Afyuni M. 2012. Effects of inorganic and organic fractions of enriched cow manure and sewage sludge on distribution of lead chemical fractionation in soil. Sci. & Technol. Agric. & Natur. Resources., Water and Soil Sci, 16(60), 12. (in Persian with English abstract).
7- Brümmer G. 1986. Heavy metal species, mobility and availability in soils: Springer.
8- Dechun S., Jianping X., Weiping J., and Woonchung W. 2009. Cadmium uptake and speciation changes in the rhizosphere of cadmium accumulator and non-accumulator oilseed rape varieties. Journal of Environmental Sciences, 21(8), 1125-1128.
9- Eriksson J. E. 1990. Factors influencing adsorption and plant uptake of cadmium from agricultural soils. Swedish University of Agricultural Sciences Uppsala.
10- Fard A. G., Hosseini H. M., Besharati H., and Savaghebi G. R. 2013. Study on chemical forms of lead and zinc in the rhizosphere of some maize and canola cultivars. Water and Soil, 26(6), 13. (in Persian with English abstract).
11- Gholami M., and Motlagh M. B. 2011. Distribution of zinc forms and the relationship of these fractions with soil properties in some soils of Golestan Province. Soil Management and Sustainable, 1(2), 19. (in Persian with English abstract).
12- Grant C., Buckley W., Bailey L., and Selles F. 1998. Cadmium accumulation in crops. Canadian Journal of Plant Science, 78(1), 1-17.
13- Haghiri F. 1974. Plant uptake of cadmium as influenced by cation exchange capacity, organic matter, zinc, and soil temperature. Journal of Environmental Quality, 3(2), 180-183.
14- He Q., and Singh B. 1993. Effect of organic matter on the distribution, extractability and uptake of cadmium in soils. Journal of Soil Science, 44(4), 641-650.
15- Hinesly T., Redborg K., Ziegler E., and Alexander J. 1982. Effect of soil cation exchange capacity on the uptake of cadmium by corn. Soil Science Society of America Journal, 46(3), 490-497.
16- Kim K.-R., Owens G., and Naidu R. 2010. Effect of root-induced chemical changes on dynamics and plant uptake of heavy metals in rhizosphere soils. Pedosphere, 20(4), 494-504.
17- Kim K.-R., Owens G., Naidu R., and Kwon S.-l. 2010. Influence of plant roots on rhizosphere soil solution composition of long-term contaminated soils. Geoderma, 155(1), 86-92.
18- Marchiol L., Assolari S., Sacco P., and Zerbi G. 2004. Phytoextraction of heavy metals by canola (Brassica napus) and radish (Raphanus sativus) grown on multicontaminated soil. Environmental Pollution, 132(1), 21-27.
19- Martinez-Alcala I., Walker D., and Bernal M. 2010. Chemical and biological properties in the rhizosphere of Lupinus albus alter soil heavy metal fractionation. Ecotoxicology and Environmental Safety, 73(4), 595-602.
20- Mohamed I., Ahamadou B., Li M., Gong C., Cai P., Liang W., and Huang Q. 2010. Fractionation of copper and cadmium and their binding with soil organic matter in a contaminated soil amended with organic materials. Journal of Soils and Sediments, 10(6), 973-982.
21- Narwal R., and Singh B. 1998. Effect of organic materials on partitioning, extractability and plant uptake of metals in an alum shale soil. Water, Air, and Soil Pollution, 103(1-4), 405-421.
22- Ravanbakhsh M. H., Fotovat A., and Haghnia G. 2011. Effect of sewage sludge, clay content and time on the fractionation of nickel and cadmium in selected calcareous soils. Water and Soil, 25(3), 13. (in Persian with English abstract).
23- Ravanbaksh M.H., Fotovat A., and Haghnia GH. 2009. The effect of sewage sludge and incubation time on the availability and speciation of Nickel and Cadmium in the calcareous soil solutions. Water and Soil, 23(1), 11. (in Persian with English abstract).
24- Reyhanitabar A., Karimian N., Muazardalan M., Savaghebi G. R., and Ghannadha M. R. 2006. Zinc Fractions of Selected Calcareous Soils of Tehran Province and Their Relationships with Soil Characteristics. Water and Soil science (Science and Technology of Agriculture and Natural Resources), 10(3), 11. (in Persian with English abstract).
25- Saadat K., Motlagh M. B., Dordipour E., and Ghasemnezhad A. 2012. Influence of sewage sludge on some soil properties, yield and concentration of lead and cadmium in roots and shoots of Maize. Soil Management and Sustainable, 2(2), 22. (in Persian with English abstract).
26- Shuman L., Dudka S., and Das K. 2002. Cadmium forms and plant availability in compost-amended soil. Communications in Soil Science and Plant Analysis, 33(5-6), 737-748.
27- Sposito G., Lund L. J., and Chang A. C. 1981. Trace Metal Chemistry in Arid-zone Field Soils Amended with Sewage Sludge: I. Fractionation of Ni, Cu, Zn, Cd, and Pb in Solid Phases. Soil Science Society of America Journal, 46(2), 260-264.
28- Tao S., Chen Y., Xu F., Cao J., and Li B. 2003. Changes of copper speciation in maize rhizosphere soil. Environmental Pollution, 122(3), 447-454.
29- Tessier A., and Campbell P. 1987. Partitioning of trace metals in sediments: relationships with bioavailability. Hydrobiologia, 149(1), 43-52.
30- Tessier A., Campbell P. G., and Bisson M. 1979. Sequential extraction procedure for the speciation of particulate trace metals. Analytical chemistry, 51(7), 844-851.
31- Walker D. J., Clemente R., Roig A., and Bernal M. P. 2003. The effects of soil amendments on heavy metal bioavailability in two contaminated Mediterranean soils. Environmental Pollution, 122(2), 303-312.
32- Wang J., Zhang C., and Jin Z. 2009. The distribution and phytoavailability of heavy metal fractions in rhizosphere soils of Paulowniu fortunei (seem) Hems near a Pb/Zn smelter in Guangdong, PR China. Geoderma, 148(3), 229-306.
33- Wang Z., Shan X.-q., and Zhang S. 2002. Comparison between fractionation and bioavailability of trace elements in rhizosphere and bulk soils. Chemosphere, 46(8), 1163-1171.
34- Wenzel W. W., Wieshammer G., Fitz W. J., and Puschenreiter M. 2000. Novel rhizobox design to assess rhizosphere characteristics at high spatial resolution. Plant and soil, 237, 37–45.
35- Wuana R. A., and Okieimen F. E. 2011. Heavy metals in contaminated soils: a review of sources, chemistry, risks and best available strategies for remediation. ISRN Ecology, 2011.
36- Xian X. 1989. Effect of chemical forms of cadmium, zinc, and lead in polluted soils on their uptake by cabbage plants. Plant and Soil, 113(2), 257-264.
37- Yanai J., Mabuchi N., Moritsuka N., and Kosaki T. 2004. Distribution and forms of cadmium on the rhizosphere of Brassica juncea in Cd-contaminated soils and implications for phytoremediation. Soil Science and Plant Nutrition, 50(3), 423-430.
38- Youssef R. A., and Chino M. 1988. Development of a new rhizobox system to study the nutrient status in the rhizosphere. Soil Science and Plant Nutrition, 34(3), 461-465.
39- Ziyaee M., and Hosseini H. M. S. 2013. Assessment of lead extractable changes with different extractants in rhizosphere and bulk soil of corn (Zea mays) and canola (Brassica napus) and lead amounts in these two plants. Soil Management and Sustainable, 3(1), 17. (in Persian with English abstract).