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ارزیابی زیست دسترسپذیری، تحرک و فرمهای شیمیایی فلزات سنگین در رسوبات لایروبیشده از تالاب انزلی
|مقاله 13، دوره 41، شماره 3، مهر 1394، صفحه 665-679 اصل مقاله (1.37 M)|
|نوع مقاله: مقاله پژوهشی|
|شناسه دیجیتال (DOI): 10.22059/jes.2015.55904|
|پروین برنجکار* 1؛ محسن سعیدی2|
|1کارشناس ارشد مهندسی عمران- مهندسی محیطزیست، دانشگاه علم و صنعت ایران|
|2دانشیار گروه مهندسی عمران، دانشگاه علم و صنعت ایران|
|آلایندههای بسیاری از جمله فلزات سنگین از راههای مختلف به محیطهای آبی وارد و از طریق رسوبات جذب میشوند. لایروبی رسوبات و انباشت آنها در خشکی، سبب میشود تا فلزات با قرارگرفتن در معرض هوا، آزاد و در فرمهای قابل دسترس ظاهر شوند. فرمهای شیمیایی فلزات سنگین در رسوبات لایروبیشدۀ تالاب انزلی از طریق تفکیک شیمیایی تعیین شد. برای ارزیابی دسترسی زیستی فلزات، آزمایشهای دسترسی گیاهی CaCl2 و EDTA و آزمون شبیهسازی شرایط شکمی انسان (SBET) صورت گرفت. به علت وجود احتمال نشت فلزات به آبهای زیرزمینی یا ورود مجدد آنها به تالاب، آزمونهای تعیین ویژگی سمیت (TCLP) و شبیهساز باران (SPLP) انجام گرفتند. برای تفسیر نتایج تفکیک شیمیایی و آزمونهای دسترسی زیستی از شاخصهای mRAC و BRAI استفاده شد. سرب و کادمیوم بیش از فلزات دیگر در فازهای قابل دسترس بودند. شاخصها نشان دادند که سطح خطر آثار متوسط و خطر قابلیت دسترسی فلزات برای گیاهان و انسان به ترتیب در حد متوسط و بسیار زیاد است. غلظت فلزات در شیرابۀ آزمون TCLP کمتر از حدود سمیت بود، یعنی رسوبات قابلیت استفادۀ مجدد را دارند. انباشت رسوبات لایروبیشده از تالاب انزلی، بدون اتخاذ روش مدیریتی مناسب میتواند آثار نامطلوبی در محیطزیست و موجودات بر جای گذارد.|
|تالاب انزلی؛ رسوبات لایروبیشده؛ زیست دسترسپذیری؛ فلزات سنگین؛ قابلیت حرکت|
|عنوان مقاله [English]|
|Evaluation of bioavailability, mobility and speciation of heavy metals in dredged sediments of Anzali wetland|
|Parvin Berenjkar1؛ Mohsen Saeedi2|
|1M.Sc., School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran|
|2Associate Professor, School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran|
A large volume of sediments are dredged from water bodies such as ports, waterways and wetlands and deposited on land. Sediments are typically polluted by contaminants such as heavy metals. Metals in sediments are in soluble, carbonate bound, Fe-Mn oxide, sulfide/organic matter bound and residual fractions. The metal solubility and mobility are mainly controlled by organic matter content, clay minerals, pH and redox potential. In exposure to air, metals release from loosely bound fractions and become available. One impact of dredging and on-land deposition of sediments is metal release enhancing their bioavailability and mobility. After sediments are deposited, plants start to grow; thus, metals can be up-taken by plants and become further available to the food chain. In case of human contact, there is a potential for direct accessibility of metals. Besides, long term leachability of metals can contaminate surface and ground water. According to former investigations, the mobility, availability and toxicity of metals cannot be assessed based on their total contents, and those are usually controlled by the chemical forms of metals. The metal speciation can be determined by sequential extraction procedures, and various single extraction methods can be used to evaluate their bioavailability and mobility. Other authors have studied metal leachability, bioavailability, bioaccessibility and speciation using various methods.
The Anzali International wetland was registered in the Ramsar Convention in 1975. It covers an area of 193 km2, located at the southwest coast of the Caspian Sea, in Guilan, Iran. Due to the excessive discharge of different contaminants such as heavy metals, most of which are carried by rivers, into the wetland, bed sediments have become a sink for metals. The Pasikhan River is one of the most polluted rivers leading into the south east zone of Anzali wetland. A sediment trap in placed on the entry of the river, and sediments are being dredged and deposited in places adjacent to the trap; exposing to air, heavy metals might release from soluble and bioavailable phases.
Material and methods
Sampling was carried out after dredged sediments were deposited in the area for four months.
pH of sediments, the solid density, grain-size distributions, moisture content, Atterberg limits, mineralogical composition, major elements and total metal contents were determined. A sequential extraction procedure was applied for metal speciation. The detailed scheme for 1 g sample is as follows:
Table 1 Sequential extraction procedure
10 ml of 1 molL-1 MgCl2
Room temp, 1h, shaking
10 ml of 1 molL-1 NaOAc
Room temp, 5h, shaking
20 ml of 0.04 molL-1 NH2OH·HCl in 25% (v/v) HOAc
96 °C, 6h agitation
3 ml HNO3 0.02 molL-1 + 5 ml 30% w/v, H2O2 3 ml of 30% w/v, H2O2
5 ml NH4Ac 3.2 molL-1 in 20% (v/v) HOAc
85 °C, 2h agitation
85 °C, 3h agitation
Room temp, diluted, 30mins shaking
The phytoavailability, bioaccessibility and mobility of metals were assessed using CaCl2 and EDTA, SBET and TCLP, respectively. Due to frequent precipitations in the area, SPLP test was conducted to simulate the amount of metals which can be washed and re-enter to the wetland.
Table 2 Leaching tests applied to assess dredged sediment samples
0.01 molL-1 CaCl2, L/S= 10:1
3h, room temp
0.05 molL-1 EDTA, L/S= 10:1
1h, room temp
0.4 molL-1 Glycine, L/S= 100:1
1h, 37 °C
AcOH, L/S= 20:1
H2SO4/HNO3 (60:40), L/S= 20:1
To determine release risk of metals, modified risk assessment code (mRAC) based on metal fractionations was applied. To evaluate the metal bioavailability and bioaccessibility, a new bioavailability/bioaccessibility index (BRAI) is used based on EDTA and SBET results.
Results and discussion
Sediments were classified as ML. Quartz was the dominant mineral observed in the XRD analysis which accorded with XRF. Concentrations of most metals exceeded those of earth’s crust, global average, Shijan zone of wetland and the Caspian Sea. Thus, these fine-grained sediments contained a high amount of metals. The sequential extraction showed that the highest percentages of metal associations with exchangeable, carbonate bound, Fe-Mn oxide, organic matter and residual fractions were related to Pb and Cd, Mn, Zn, Cu and Cr, respectively. Using the sum of metal extractions in exchangeable and carbonate fractions, the mRAC value was equal to 44.09 indicating high potential adverse impact.
The actual bioavailability of metals evaluated by CaCl2 was low due to low concentrations of extracted metals (Fig. 1), and the concentrations of Pb and Cd, which were mainly associated with exchangeable fraction, were higher than those of other metals. EDTA extracts the potential bioavailable fraction of metals. Compared to other studied metals, high amounts of Cu, Mn, Pb and Cd were extracted by EDTA (Fig. 1); Cu and Mn were mainly associated with organic matter and carbonate bound fractions, respectively. Based on results obtained from EDTA extraction, the calculated BRAI value of 2.4 showed medium risk of bioavailability. The concentrations of metals extracted by SBET method were high (Fig. 1). The highest concentrations were reported for Pb and Cd, almost all fractions of which were extracted. Based on SBET results, the calculated BRAI value was equal to 7.14 indicating very high risk of bioaccessibility. The release of Pb, Cd and Mn by TCLP method was higher than release of other metals (Fig. 1). Pb, Cd and Cr concentrations were below the USEPA regulatory limits indicating that sediments were not toxic and beneficial use of them is viable. The contents of Pb and Cd in the SPLP leachate were high compared to other metals with low concentrations (Fig. 1). Metal concentrations in SPLP leachate were commonly lower than drinking water standards.
Figure 1. Metal extraction by bioavailability/bioaccessibility and mobility tests.
In all extractions, the highest metal contents were reported for Pb and Cd and the lowest for Cr. The bioavailability of metals was in the decreasing order of Cd ~ Pb > Cu > Mn > Zn > Fe > Ni > Cr. Metal extractability of methods was in the order of SBET > TCLP > EDTA > SPLP > CaCl2 for Pb, Ni, Cd and SBET > EDTA > TCLP > SPLP > CaCl2 for the rest. The potential bioavailability of metals was higher than their actual bioavailability while the bioaccessibility of them was the highest. The concentrations of metals extracted by SBET were higher than those of TCLP, which was due to acidic pH and higher temperature in SBET. Although TCLP and SPLP methods are very similar, metal concentrations in TCLP were higher than SPLP. TCLP represents metal leaching under landfill conditions while SPLP simulates their release owing to precipitation which is an easier condition.
In this study, bioavailability, mobility and speciation of heavy metals in dredged sediments of Anzali wetland are assessed. The metal speciation and the mRAC index showed high potential adverse impacts. BRAI index using bioavailability and bioaccessibility test results represented medium and very high risks. Metal concentrations in TCLP test were lower than USEPA limits and in SPLP test were occasionally higher than standards. Results showed that metals in sediments of Anzali wetland can be up-taken by plants. Moreover, metals can leach to the underlying soil and contaminate ground water. They can also be washed due to the precipitation and re-enter to the wetland. On the other hand, sediments are not toxic and can be used for beneficial purposes. It can be concluded that unless properly managed, to deposit sediments can cause adverse effects on the environment and terrestrial organisms of Anzali wetland.
|Heavy metals, Bioavailability, Mobility, Dredged sediments, Anzali wetland|
سازمان حفاظت محیطزیست ایران. 1373. استاندارد خروجی فاضلابها.
غضبان، ف.، زارع، م.، 1390. بررسی منشأ آلودگی فلزات سنگین در رسوبات تالاب انزلی (شمال ایران)، محیطشناسی، سال سی و هفتم، شمارۀ 57، صص 45-56.
مؤسسۀ استاندارد و تحقیقات ایران. 1376. استاندارد 1053: ویژگیهای آب آشامیدنی، چاپ چهارم، تجدیدنظر پنجم.
ASTM (American Society for Testing and Materials). 2002. Standard test methods for specific gravity of soil solids by water pycnometer (ASTM D854-02). ASTM, West Conshohocken, PA.
ASTM (American Society for Testing and Materials). 2007. Standard test method for particle-size analysis of soils (ASTM D422-63). ASTM, West Conshohocken, PA.
ASTM (American Society for Testing and Materials). 2010a. Standard test methods for laboratory determination of water (moisture) content of soil and rock by mass (ASTM D2216-10). ASTM, West Conshohocken, PA.
ASTM (American Society for Testing and Materials). 2010b. Standard test methods for liquid limit, plastic limit, and plasticity index of soils (ASTM D4318-10). ASTM, West Conshohocken, PA.
Beckett, P. H. 1989. The use of extractants in studies on trace metals in soils, sewage sludges, and sludge-treated soils. In: Advances in soil science. Springer, pp. 143-176.
Calmano, W., Hong, J., Förstner, U. 1993. Binding and mobilization of heavy metals in contaminated sediments affected by pH and redox potential.Water science and technology, 28: pp. 223-223.
Cappuyns, V., Swennen, R., Verhulst, J. 2006. Assessment of heavy metal mobility in dredged sediments: porewater analysis, single and sequential extractions. Soil & sediment contamination, 15: pp. 169-186.
de Mora, S., Sheikholeslami, M. R., Wyse, E., Azemard, S., Cassi, R. 2004. An assessment of metal contamination in coastal sediments of the Caspian Sea. Marine Pollution Bulletin, 48: pp. 61-77.
Devesa-Rey, R., Díaz-Fierros, F., Barral, M. T. 2010. Trace metals in river bed sediments: An assessment of their partitioning and bioavailability by using multivariate exploratory analysis. Journal of environmental management, 91: pp. 2471-2477.
Drexler, J. W., Brattin, W. J. 2007. An in vitro procedure for estimation of lead relative bioavailability: with validation. Human and Ecological Risk Assessment, 13: pp. 383-401.
Ferraz, M.C.M., Lourenco, J.C.N. 2000. The inﬂuence of organic matter content of contaminated soils on the leaching rate of heavy metals. Environtal Progress, 19: pp. 53-58.
Gupta, S. K., Vollmer, M. K., Krebs, R. 1996. The importance of mobile, mobilisable and pseudo total heavy metal fractions in soil for three-level risk assessment and risk management. Science of the Total Environment, 178: pp. 11-20.
Hakanson, L. 1980. An ecological risk index for aquatic pollution control. A sedimentological approach. Water research, 14: pp. 975-1001.
Jamshidi-Zanjani, A. 2013. Development of index of heavy metals pollution intensity in aquatic sediments (unpublished doctoral dissertation). Iran University of Science and Technology, Tehran, Iran.
Jamshidi-Zanjani, A., Saeedi, M. 2013. Metal pollution assessment and multivariate analysis in sediment of Anzali international wetland. Environmental Earth Sciences. 70: pp. 1791-1808.
Jamshidi-Zanjani, A., Saeedi, M., Li, L. Y. 2014. A risk assessment index for bioavailability of metals in sediments: Anzali International Wetland case study.Environmental Earth Sciences doi: 10.1007/s12665-014-3562-5
JICA (Japan International Cooperation Agency). 2005. The study on integrated management for ecosystem conservation of the Anzali wetland in the Islamic Republic of Iran. Final report submitted to department of environment.
Karbassi, A. R., Nabi-Bidhendi, G.R., Bayati, I. (2005). Environmental geochemistry of heavy metals in a sediment core off Bushehr, Persian Gulf. Iranian Journal of Environmental Health Science & Engineering, 2: pp. 255-260.
Klavinš, M., Briede, A., Rodinov, V., Kokorite, I., Parele, E., Klavina, I. 2000. Heavy metals in rivers of Latvia. Science of the Total Environment, 262: pp. 175-183.
Liu, R., Zhao, D. 2007. The leachability, bioaccessibility, and speciation of Cu in the sediment of channel catfish ponds. Environmental Pollution, 147: pp. 593-603.
Luo, X. S., Yu, S., Li, X. D. 2012. The mobility, bioavailability, and human bioaccessibility of trace metals in urban soils of Hong Kong. Applied Geochemistry, 27: pp. 995-1004.
Madrid, F., Biasioli, M., Ajmone-Marsan, F. 2008. Availability and bioaccessibility of metals in fine particles of some urban soils. Archives of Environmental Contamination and Toxicology, 55: pp. 21-32.
Magdaleno, A., Mendelson, A., de Iorio, A. F., Rendina, A., Moretton, J. 2008. Genotoxicity of leachates from highly polluted lowland river sediments destined for disposal in landfill. Waste management, 28: pp. 2134-2139.
Maskell, J.E., Thornton, I. 1998. Chemical partitioning of heavy metals in soil rock at historical lead smelter site. Water, air and soil pollution, 108: pp.391-409.
Morillo, J., Usero, J., Rojas, R. 2008. Fractionation of metals and As in sediments from a biosphere reserve (Odiel salt marshes) affected by acidic mine drainage. Environmental monitoring and assessment, 139: pp. 329-337.
Novozamsky, I., Lexmond, T. M., Houba, V. J. G. 1993. A single extraction procedure of soil for evaluation of uptake of some heavy metals by plants.International Journal of Environmental Analytical Chemistry, 51: pp. 47-58.
Pacifico, R., Adamo, P., Cremisini, C., Spaziani, F., Ferrara, L. 2007. A geochemical analytical approach for the evaluation of heavy metal distribution in lagoon sediments. Journal of Soils and Sediments, 7: pp. 313-325.
Pardo, R., Barrado, E., Lourdes, P., Vega, M. 1990. Determination and speciation of heavy metals in sediments of the Pisuerga River. Water Research, 24: pp. 373-379.
Park, C., Allaby, M. (Eds.). 2013. A dictionary of environment and conservation. Oxford University Press.
Piou, S., Bataillard, P., Laboudigue, A., Férard, J. F., Masfaraud, J. F. 2009. Changes in the geochemistry and ecotoxicity of a Zn and Cd contaminated dredged sediment over time after land disposal. Environmental research, 109: pp. 712-720.
Poggio, L., Vrščaj, B., Schulin, R., Hepperle, E., Ajmone Marsan, F. 2009. Metals pollution and human bioaccessibility of topsoils in Grugliasco (Italy).Environmental Pollution, 157: pp. 680-689.
Quevauviller, P., Rauret, G., Rubio, R., López-Sánchez, J. F., Ure, A., Bacon, J., Muntau, H. 1997. Certified reference materials for the quality control of EDTA-and acetic acid-extractable contents of trace elements in sewage sludge amended soils (CRMs 483 and 484). Fresenius' journal of analytical chemistry, 357: pp. 611-618.
Ramos, L., Gonza lez, M.J., Herna ndez, L.M. 1999. Sequential extraction of copper, lead, cadmium and zinc in sediments from Ebro River (spain): relationship with levels detected in earthworms. Bull. Environ. Bulletin of Environmental Contamination and Toxicology, 62: pp. 301-308.
Rath, P., Panda, U. C., Bhatta, D., Sahu, K. C. 2009. Use of sequential leaching, mineralogy, morphology and multivariate statistical technique for quantifying metal pollution in highly polluted aquatic sediments—a case study: Brahmani and Nandira Rivers, India. Journal of Hazardous Materials, 163: pp. 632-644.
Reddy, K. R., DeLaune, R. D. 2004. Biogeochemistry of wetlands: science and applications. New York: Crc Press.
Tessier, A., Campbell, P. G., Bisson, M. 1979. Sequential extraction procedure for the speciation of particulate trace metals. Analytical chemistry, 51: pp. 844-851.
Sahuquillo, A., Rigol, A., Rauret, G. 2003. Overview of the use of leaching/extraction tests for risk assessment of trace metals in contaminated soils and sediments. TrAC Trends in Analytical Chemistry, 22: pp. 152-159.
Salomons, W., Förstner, U. 1984. Metals in the Hydrocycle. Springer, Berlin.
Stephens, S. R., Alloway, B. J., Parker, A., Carter, J. E., Hodson, M. E. 2001. Changes in the leachability of metals from dredged canal sediments during drying and oxidation. Environmental Pollution, 114: pp. 407-413.
Tack, F. M., Verloo, M. G. 1996. Impact of single reagent extraction using NH4OAc-EDTA on the solid phase distribution of metals in a contaminated dredged sediment. Science of the total environment, 178: pp. 29-36.
Thornburg, T., Cumberland, H., Hermans, M., Childs, M. 2002, May. Sediment and Water Quality Evaluation Framework for Disposal of Dredged Material in an Upland Rehandling Facility, Portland, Oregon. (Presented Conference Paper style). In: Dredging '02, Orlando, Florida. ASCE, pp. 1-15
Turekian, K. K., Wedepohl, K. H. 1961. Distribution of the elements in some major units of the earth's crust. Geological Society of America Bulletin, 72: pp. 175-192.
Udovic, M., Drobne, D., Lestan, D. 2009. Bioaccumulation in Porcellio scaber (Crustacea, Isopoda) as a measure of the EDTA remediation efficiency of metal-polluted soil. Environmental pollution, 157: pp. 2822-2829.
USEPA (U.S. Environmental Protection Agency). 1997. Test Methods for Evaluating Solid Waste Physical/Chemical Methods (SW-846).
USEPA (U.S. Environmental Protection Agency). 2006. Drinking Water Standards and Health Advisories. http://water.epa.gov/action/advisories/drinking/upload/2009_04_27_criteria_drinking_dwstandards.pdf
Wade ,R., Price, R.A., Simmers, J.W., Price, C., Palermo, M.R., Gibson, A.B. 2002. Evaluation of Dredged Material Disposal and Management for Appomattox River Federal Navigation Channel, Petersburg, Virginia: phase I and II: Environmental and engineering studies. U.S. Army Engineer Research and Development Center, Vicksburg, MS.
Zhu, Q. H., Huang, D. Y., Liu, S. L., Luo, Z. C., Zhu, H. H., Zhou, B., Lei, M., Rao, Z. X., Cao, X. L. 2012. Assessment of single extraction methods for evaluating the immobilization effect of amendments on cadmium in contaminated acidic paddy soil. Plant Soil Environ, 58: pp. 98-103.
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