Environmental Toxicology and Chemistry, Vol. 34, No. 2, pp. 252–257, 2015 # 2014 SETAC Printed in the USA
BIOACCUMULATION OF METALS AND METALLOIDS IN MEDICINAL PLANT IPOMOEA PES-CAPRAE FROM AREAS IMPACTED BY TSUNAMI LIDIA KOZAK,y MIKOŁAJ KOKOCINSKI ,z PRZEMYSŁAW NIEDZIELSKI,*y and STANISŁAW LORENCx
yDepartment of Analytical Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Pozna n, Poland zDepartment of Hydrobiology, Faculty of Biology, Adam Mickiewicz University, Pozna n, Poland xInstitute of Geology, Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, Pozna n, Poland (Submitted 16 December 2013; Returned for Revision 28 October 2014; Accepted 30 October 2014)
Abstract: Tsunami events may have an enormous impact on the functioning of aquatic and terrestrial ecosystems by altering various relationships with biotic components. Concentrations of acid-leachable fractions of heavy metals and metalloids in soils and plant samples from areas affected by the December 2004 tsunami in Thailand were determined. Ipomoea pes-caprae, a common plant species growing along the seashore of this region, and frequently used in folk medicine, was selected to assess the presence of selected elements. Elevated amounts of Cd, Pb, Zn, and As in soil samples, and Pb, Zn, As, Se, Cr, and Ni in plant samples were determined from the tsunami-impacted regions for comparison with reference locations. The flowers of Ipomoea pes-caprae contained the highest amounts of these metals, followed by its leaves, and stems. In addition, its bioaccumulation factor (BAF) supports this capability of high metal uptake by Ipomoea pes-caprae from the areas affected by the tsunami in comparison with a reference site. This uptake was followed by the translocation of these elements to the various plant components. The presence of these toxic metals in Ipomoea pes-caprae growing in contaminated soils should be a concern of those who use this plant for medicinal purposes. Further studies on the content of heavy metals and metalloids in this plant in relation to human health concerns are recommended. Environ Toxicol Chem 2015;34:252–257. # 2014 SETAC Keywords: Bioaccumulation
Heavy metals
Sediment chemistry
Tsunami
composed of sand, boulders, such as those derived from coral reefs, and land soil. Any deposits, such as those containing metals, are then exposed to new environmental factors that can influence their uptake by various organisms [4]. Although many studies on animals and plants growing on soils contaminated by metals have been conducted, little is known about metal accumulation by plants inhabiting regions containing tsunami deposits. Among the different plant species growing at the seashore of an area in Thailand impacted by the 2004 tsunami is Ipomoea pes-caprae (R. Br. [Convolvulaceae]). This is 1 of the most widely distributed beach plants throughout the world’s tropical and subtropical regions. It frequently occurs along marine coastal beaches above the high tide line, where it aids in the stabilization of dunes common to these shores. Ipomoea pescaprae is also used as a medicinal plant in the folk medicine of many countries as a remedy against several diseases and ailments. These include inflammation and pain [7], fatigue, strain, arthritis, and rheumatism [8]. Extracts from this plant have antimicrobial, anti-insulinogenic, hypoglycemic, and antispasmodic properties, or have a protective effect against ciguatoxin or brevetoxin, and an antagonistic effect to histamine and jellyfish poison [8]. Heavy metals are a known source of contamination in many traditional remedies, and studies have indicated high levels of As, Pb, and Hg in several Asian and Indian folk remedies [9,10]. Thus, the monitoring of traditional medicines for their content and safety has been recommended to protect public health [11]. In addition, the uptake of heavy metals in plants can have health effects in humans and animals [12]. Among the natural defense strategies of organisms against toxic metals is binding them with proteins and organic acids followed by their incorporation in the vacuoles of plant cells or in the cell walls of roots and
INTRODUCTION
The presence of heavy metals in various plants has attracted attention because of their uses as food and medicinal sources, and because they may be potentially harmful to humans and animals [1,2]. The concentration of heavy metals in the environment largely depends on, and is generally influenced by, the type and amount of anthropological discharges in a particular location. Major sources of metal contamination have been associated with mining activities, industrial emissions, and the application of insecticides and fertilizers in agriculture practices [3]. Contributions from natural causes, however, should not be neglected and are associated with soil and rock erosion, volcanic eruptions, biogenic sources, including accumulation of litter in tropical forests, and forest wildfires [4]. The first 2 sources account for 80% of all the natural causes [5]. Some of the heavy metals and metalloids occur as hardly water-soluble natural components of the Earth’s crust, which, however, can be microbiologically transformed to more biologically active forms. Factors responsible for the transportation of heavy metals also play an important role in their availability and exposure to plants and animals. In addition to human activities, natural events such as tsunamis can introduce elevated concentrations of heavy metals to the environment. Tsunami deposits are consequences of the deposition process during a tsunami event. A tsunami deposit consists of a few to several tens of centimeters thick sediment layer on the inundated coastal land areas [6]. These deposits may contain material transported from both land and marine ecosystems and are * Address correspondence to [email protected] Published online 1 November 2014 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/etc.2794 252
Bioaccumulation by Ipomoea from tsunami impacted areas
stems [13,14]. Different organisms can accumulate various concentrations of certain metals, and these plants have been classified as accumulators, excluders, and indicators [15]. Accumulators are plants (also referred to as hyperaccumulators) that can accumulate high concentrations of specific elements. Moreover, the threat associated with heavy metals is often underestimated because they bioaccumulate undetected in the various components of the food chain, and their toxic properties may be released later when translocated to living organisms fed on contaminated food [16]. Chemical studies of 2004 tsunami deposits in Thailand showed elevated concentrations of heavy metals and metalloids in the soil from areas impacted by the tsunami [17–19]. In addition, some of these element concentrations remained elevated 2 yr to 3 yr after the tsunami event, even when they were exposed to periods of heavy rainfall during the rainy season responsible for postdepositional processes (erosion) [6]. Knowledge regarding the capability of Ipomoea pes-caprae to accumulate heavy metals and metalloids is very limited. A phenological study by Kuki et al. in 2008 [20] showed, however, that iron ore industry emissions affected the reproductive effort of this species, although it did not accumulate Fe to toxic levels. Therefore, the objectives of the present study were 1) to determine and compare concentrations of trace elements (heavy metals and metalloids) in Ipomoea pes-caprae growing at sites affected by tsunami deposits, plus the soil from these locations; and 2) to determine the trace metal accumulation ratio in the different plant components of Ipomoea pes-caprae. MATERIALS AND METHODS
Collection of soil and plant samples
Plant samples of Ipomoea pes-caprae were collected from 7 sites in 2007 and from 6 sites in 2008 (Table 1) in 3 areas flooded during the 26th December 2004 tsunami: southern Kho Khao Island, along the Andaman coast, and on Phuket Island in Thailand. Three to 5 whole plants were randomly collected from each location. At the same time, associated soil from the rooting zone from 0 cm to 20 cm depth was collected and stored in polyethylene bags. Control plant and soil samples were also collected from areas not inundated by tsunami waves and used as a reference throughout the present study. Areas not impacted by the tsunami were determined based on an earlier study by Szczucinski et al. 2006 [18], and were situated 300 m to 800 m
Environ Toxicol Chem 34, 2015
253
from tsunami-affected areas, detailed descriptions of the present studies area and sampling sites are provided. Sample preparation
The soil samples were collected using polyethylene tools and stored in polyethylene bags. Collected plants were dried in the open air and stored in polyethylene bags. The whole plants (washed with deionized water) collected in 2007 were lyophilized and then homogenized by grinding. Plant samples collected in 2008 were washed with deionized water and the plant components separated into leaves, flowers, and stems, and then lyophilized and homogenized by grinding. Soil samples collected in 2007 and 2008 were lyophilized and then homogenized by grinding. Chemical analysis
Both plant and soil samples were analyzed for heavy metal (Cd, Cr, Cu, Ni, Pb, and Zn) and metalloid (As, Se, and Sb) content. In the soil samples, the acid-leachable fractions of soil under the plants were considered. Heavy metal and metalloids from the acidleachable soil fractions were analyzed from extracts obtained by 0.5 h extraction with 2 mol L1 HCl at 80 8C [17]. The 1.50 g of the plant components were mineralized in 14.0 mL 65% HNO3 and 1.0 mL 30% H2O2 at 98 8C for a 20-h extraction period and filtered through a medium-size qualitative filter (rinsed with 200 mL of distilled water) [21]. The mineralization of the samples was provided in triplicates. Metal concentrations were measured by using flame atomic absorption spectrometry (AAS). The following determination conditions were applied (the background correction with a deuterium lamp has been used): Cr: wavelength 357.9 nm, slit 0.2 nm; Cu: wavelength 324.8 nm, slit 0.5 nm; Ni: wavelength 232.0 nm, slit 0.2 nm; Cd: wavelength 228.8 nm, slit 0.5 nm; Pb: wavelength 217.0 nm, slit 1.0 nm; and Zn: wavelength 213.9 nm, slit 1.0 nm. The detection limits were at the level of 0.1 mg kg1, and the analytical range to 100 mg kg1 for all of the metals. Metalloids were determined by AAS with hydride generation (HGAAS); the following determination conditions were applied (no background correction): As: wavelength 193.7 nm, slit 0.5 nm; Sb: wavelength 217.6 nm, slit 0.2 nm; and Se: wavelength 196.0 nm, slit 1.0 nm; the detection limits were at the level of 1 mg kg1 and an analytical range to 100 mg kg1 for As, Sb, and Se. In the case of the higher element concentration, the samples have been appropriately diluted. The correlation coefficients obtained for calibration curves were higher than 0.9950. The uncertainty of the entire analytical process did not exceed 20% for all determined
Table 1. The list of sampling sites (south Thailand, the coast of the Andamanian Sea) for post tsunami soil analysis and bioaccumulation factor determination Sampling site
Location
Latitude N
Longitude E
2 3 4 5 6 Reference site
Bang Mor Kho Koh Khao Kho Kho Khan Kho Kho Khan Kho Kho Khan Kho Kho Khan Kho Khao CS
088490 15.900 098000 01.300 088560 00.800 088530 07.000 088540 09.300 088520 09.900 088490 57.400
988160 03.500 988150 08.100 988150 10.500 988150 14.400 988150 01.700 988160 04.200 988160 20.200
1 2 3 4 5 Reference site
Patong Beach Bang Mor Kho Kho Khan Kho Kho Khan Kho Kho Khan Ban Bang Niang
078520 55.200 088500 00.700 088530 03.100 098000 47.400 088550 04.100 088400 56.800
988170 18.900 988150 58.500 988150 55.100 988150 23.400 988140 59.400 988140 35.600
2007 year 1
2008 year
254
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L. Kozak et al.
elements. Traceability studies have been provided by certified reference materials analysis and by the method of standard addition. To determine the relationship between the individual element concentrations in the soil and plant components, a bioaccumulation factor (BAF) was calculated, using the following formula: BAF ¼ Cp=Cs
ð1Þ
where BAF is the bioaccumulation factor, Cp is the concentration of a given element in the plant or plant component (flower, leaf, stem), and Cs is the concentration of the given element in the soil. RESULTS
Heavy metals and metalloids in soil and whole plants
Concentrations of heavy metals and metalloids in soil and plant samples collected in 2007 are listed in Table 2. The median concentrations of Pb, Zn, and Cu among heavy metals and As among metalloids were the highest in both the soil and plant samples. The median concentrations of metals in the soil decreased in the following order: Pb > Zn > Cr > Cu > Cd > Ni, whereas the median concentrations of metals in plants decreased: Zn > Cu > Pb > Cr > Cd > Ni. The median concentrations of Cd, Pb, and Ni were similar in soil and plants, and median concentrations of Cr, Cu, and Zn were higher in plants. The median concentrations of Pb, Zn, and As in the soil were 11.5 mg kg1, 7.2 mg kg1, and 684 mg kg1, respectively, and in plants 11.0 mg kg1, 28.0 mg kg1, and 501 mg kg1, respectively; both were higher than in the reference site. The concentrations of metals and metalloids, however, did not differ significantly (p < 0.05) between sampling sites and the reference site for both soil and plant samples (based on the results of the runs test [Wald–Wolfowitz test] and maximum normed residual test [Grubbs test]). Distribution of heavy metals in different plant parts
Concentrations of heavy metals and metalloids in the soil and plant samples collected in 2008 are given in Table 3. The median concentrations of Pb and Zn (6.9 mg kg1, 4.4 mg kg1, respectively) among heavy metals and As (906 mg kg1) among metalloids were the highest in the soil samples. The median concentrations of metals in the soil decreased in the following order: Pb > Zn > > Ni > Cr > Cu > Cd.
The median concentration of As in the soil was higher in sampling sites in comparison with the reference site; however, concentrations of most of the heavy metals and metalloids we investigated did not differ significantly (based on the results of the runs test [Wald–Wolfowitz test] and maximum normed residual test [Grubbs test]) among sampling sites and between sampling sites and the reference site. Concentrations of heavy metals and metalloids varied in the different plant components of Ipomoea pes-caprae. Heavy metal concentrations were higher in the flowers compared with concentrations found in leaves and stems. The highest medians of metal concentrations for flowers, leaves, and stems (282 mg kg1, 10.9 mg kg1, and 28.0 mg kg1, respectively) were observed for Zn. The median concentrations of metals decreased in the following order: Zn > Ni > Pb > Cr > Cu > Cd in flowers, Zn > Cr > Ni > Pb > Cu > Cd in leaves, and Zn > Ni > Cr > Cu > Pb > Cd in stems. The highest median concentration of As was observed in leaves. The median concentrations of all metals were higher in flowers than in soil from the sampling sites, whereas the median concentrations of Cd and Pb were lower in leaves, and stems in comparison with concentrations in soil. The median concentrations of the rest of the metals we investigated were higher in the leaves, and stems than the concentrations found in the soil. Concentrations of heavy metals and metalloids in flowers, stems, and leaves did not differ significantly among sampling sites, nor between sampling sites and the reference site. Accumulation of heavy metals and metalloids in Ipomoea pescaprae
The BAFs for Ipomoea pes-caprae collected in 2007 indicated that it was most efficient in taking up Cu followed by Zn, and finally Sb. In addition, BAFs of As, Cr, and Ni were higher, and that of Cd was lower in most of the sampling sites affected by the tsunami in comparison with the reference site that was not impacted by the tsunami. The BAFs of the other metals reached similar values from these locations (Table 4). The 2008 analysis of heavy metals and metalloids within the plant components from all sites indicated that the uptake of Cr, Cu, Ni, Zn, Pb, and Cd was highest in the flowers followed by leaves, and stems, respectively. The BAFs for Cu and Zn was higher in stems than in the leaves. Higher BAFs for Ni, Cr, Zn, and Pb were in all plant components at most of the sites affected by the tsunami. The uptake of Cd and Cu was greater at the reference site (Table 5). The BAFs of Se and As varied among the plant components and at the sampling locations, but generally was higher at the reference site (Table 5).
Table 2. Concentrations (for dry mass) of heavy metals and metalloids in plant and soil in 2007a Site 1
Heavy metals Cd (mg kg–1) Pb (mg kg–1) Ni (mg kg–1) Cr (mg kg–1) Cu (mg kg–1) Zn (mg kg–1) Metalloids Se (mg kg–1) As (mg kg–1) Sb (mg kg–1) a
Site 2
Site 3
Site 4
Site 5
Site 6
Reference site
Soil
Plant
Soil
Plant
Soil
Plant
Soil
Plant
Soil
Plant
Soil
Plant
Soil
Plant
3.3 29 0.6 6.7 1.9 11
1.5 13 0.2 0.4 14 38
2.1 17 0.7 3.2 1.6 11
1.3 12 0.8 7.3 12 31
0.7 8.0 0.4 1.9 1.0 7.7
1.2 11 0.4 8.2 3.1 20
0.7 9.0 0.5 3.2 1.3 5.5
1.5 11 0.6 15 11 32
1.5 14 0.6 3.0 1.0 6.8
1.1 7.7 0.3 3.9 5.4 23
0.5 7.2 0.1 1.3 0.9 5.1
1.2 9.9 0.3 3.0 13 25
0.2 7.3 0.8 3.6 1.8 6.0
1.2 8.3 0.5 5.9 19 22
61 915 46
41 476 102
41 879 39
30 657 93
24 472 25
25 526 91
52 586 33
39 393 104
36 782 35
36 218 97
31 499 25
33 1591 97
42 522 33
30 230 109
n ¼ 3, (uncertainty below 20%).
Bioaccumulation by Ipomoea from tsunami impacted areas
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Table 3. Concentrations (for dry mass) of heavy metals and metalloids in plant and soil in 2008a Site 1 So
F
L
Site 2 St
Heavy metals (mg kg–1) Cd 0.3 13 0.9 0.8 Pb 6.9 67 3.4 2.7 Ni 0.9 162 4.7 3.8 Cr 1.0 165 3.7 2.4 Cu 804 35 9.4 15 Zn 55 282 10.9 28 Metalloids (mg kg–1) Se 63
BIOACCUMULATION OF METALS AND METALLOIDS IN MEDICINAL PLANT IPOMOEA PES-CAPRAE FROM AREAS IMPACTED BY TSUNAMI LIDIA KOZAK,y MIKOŁAJ KOKOCINSKI ,z PRZEMYSŁAW NIEDZIELSKI,*y and STANISŁAW LORENCx
yDepartment of Analytical Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Pozna n, Poland zDepartment of Hydrobiology, Faculty of Biology, Adam Mickiewicz University, Pozna n, Poland xInstitute of Geology, Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, Pozna n, Poland (Submitted 16 December 2013; Returned for Revision 28 October 2014; Accepted 30 October 2014)
Abstract: Tsunami events may have an enormous impact on the functioning of aquatic and terrestrial ecosystems by altering various relationships with biotic components. Concentrations of acid-leachable fractions of heavy metals and metalloids in soils and plant samples from areas affected by the December 2004 tsunami in Thailand were determined. Ipomoea pes-caprae, a common plant species growing along the seashore of this region, and frequently used in folk medicine, was selected to assess the presence of selected elements. Elevated amounts of Cd, Pb, Zn, and As in soil samples, and Pb, Zn, As, Se, Cr, and Ni in plant samples were determined from the tsunami-impacted regions for comparison with reference locations. The flowers of Ipomoea pes-caprae contained the highest amounts of these metals, followed by its leaves, and stems. In addition, its bioaccumulation factor (BAF) supports this capability of high metal uptake by Ipomoea pes-caprae from the areas affected by the tsunami in comparison with a reference site. This uptake was followed by the translocation of these elements to the various plant components. The presence of these toxic metals in Ipomoea pes-caprae growing in contaminated soils should be a concern of those who use this plant for medicinal purposes. Further studies on the content of heavy metals and metalloids in this plant in relation to human health concerns are recommended. Environ Toxicol Chem 2015;34:252–257. # 2014 SETAC Keywords: Bioaccumulation
Heavy metals
Sediment chemistry
Tsunami
composed of sand, boulders, such as those derived from coral reefs, and land soil. Any deposits, such as those containing metals, are then exposed to new environmental factors that can influence their uptake by various organisms [4]. Although many studies on animals and plants growing on soils contaminated by metals have been conducted, little is known about metal accumulation by plants inhabiting regions containing tsunami deposits. Among the different plant species growing at the seashore of an area in Thailand impacted by the 2004 tsunami is Ipomoea pes-caprae (R. Br. [Convolvulaceae]). This is 1 of the most widely distributed beach plants throughout the world’s tropical and subtropical regions. It frequently occurs along marine coastal beaches above the high tide line, where it aids in the stabilization of dunes common to these shores. Ipomoea pescaprae is also used as a medicinal plant in the folk medicine of many countries as a remedy against several diseases and ailments. These include inflammation and pain [7], fatigue, strain, arthritis, and rheumatism [8]. Extracts from this plant have antimicrobial, anti-insulinogenic, hypoglycemic, and antispasmodic properties, or have a protective effect against ciguatoxin or brevetoxin, and an antagonistic effect to histamine and jellyfish poison [8]. Heavy metals are a known source of contamination in many traditional remedies, and studies have indicated high levels of As, Pb, and Hg in several Asian and Indian folk remedies [9,10]. Thus, the monitoring of traditional medicines for their content and safety has been recommended to protect public health [11]. In addition, the uptake of heavy metals in plants can have health effects in humans and animals [12]. Among the natural defense strategies of organisms against toxic metals is binding them with proteins and organic acids followed by their incorporation in the vacuoles of plant cells or in the cell walls of roots and
INTRODUCTION
The presence of heavy metals in various plants has attracted attention because of their uses as food and medicinal sources, and because they may be potentially harmful to humans and animals [1,2]. The concentration of heavy metals in the environment largely depends on, and is generally influenced by, the type and amount of anthropological discharges in a particular location. Major sources of metal contamination have been associated with mining activities, industrial emissions, and the application of insecticides and fertilizers in agriculture practices [3]. Contributions from natural causes, however, should not be neglected and are associated with soil and rock erosion, volcanic eruptions, biogenic sources, including accumulation of litter in tropical forests, and forest wildfires [4]. The first 2 sources account for 80% of all the natural causes [5]. Some of the heavy metals and metalloids occur as hardly water-soluble natural components of the Earth’s crust, which, however, can be microbiologically transformed to more biologically active forms. Factors responsible for the transportation of heavy metals also play an important role in their availability and exposure to plants and animals. In addition to human activities, natural events such as tsunamis can introduce elevated concentrations of heavy metals to the environment. Tsunami deposits are consequences of the deposition process during a tsunami event. A tsunami deposit consists of a few to several tens of centimeters thick sediment layer on the inundated coastal land areas [6]. These deposits may contain material transported from both land and marine ecosystems and are * Address correspondence to [email protected] Published online 1 November 2014 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/etc.2794 252
Bioaccumulation by Ipomoea from tsunami impacted areas
stems [13,14]. Different organisms can accumulate various concentrations of certain metals, and these plants have been classified as accumulators, excluders, and indicators [15]. Accumulators are plants (also referred to as hyperaccumulators) that can accumulate high concentrations of specific elements. Moreover, the threat associated with heavy metals is often underestimated because they bioaccumulate undetected in the various components of the food chain, and their toxic properties may be released later when translocated to living organisms fed on contaminated food [16]. Chemical studies of 2004 tsunami deposits in Thailand showed elevated concentrations of heavy metals and metalloids in the soil from areas impacted by the tsunami [17–19]. In addition, some of these element concentrations remained elevated 2 yr to 3 yr after the tsunami event, even when they were exposed to periods of heavy rainfall during the rainy season responsible for postdepositional processes (erosion) [6]. Knowledge regarding the capability of Ipomoea pes-caprae to accumulate heavy metals and metalloids is very limited. A phenological study by Kuki et al. in 2008 [20] showed, however, that iron ore industry emissions affected the reproductive effort of this species, although it did not accumulate Fe to toxic levels. Therefore, the objectives of the present study were 1) to determine and compare concentrations of trace elements (heavy metals and metalloids) in Ipomoea pes-caprae growing at sites affected by tsunami deposits, plus the soil from these locations; and 2) to determine the trace metal accumulation ratio in the different plant components of Ipomoea pes-caprae. MATERIALS AND METHODS
Collection of soil and plant samples
Plant samples of Ipomoea pes-caprae were collected from 7 sites in 2007 and from 6 sites in 2008 (Table 1) in 3 areas flooded during the 26th December 2004 tsunami: southern Kho Khao Island, along the Andaman coast, and on Phuket Island in Thailand. Three to 5 whole plants were randomly collected from each location. At the same time, associated soil from the rooting zone from 0 cm to 20 cm depth was collected and stored in polyethylene bags. Control plant and soil samples were also collected from areas not inundated by tsunami waves and used as a reference throughout the present study. Areas not impacted by the tsunami were determined based on an earlier study by Szczucinski et al. 2006 [18], and were situated 300 m to 800 m
Environ Toxicol Chem 34, 2015
253
from tsunami-affected areas, detailed descriptions of the present studies area and sampling sites are provided. Sample preparation
The soil samples were collected using polyethylene tools and stored in polyethylene bags. Collected plants were dried in the open air and stored in polyethylene bags. The whole plants (washed with deionized water) collected in 2007 were lyophilized and then homogenized by grinding. Plant samples collected in 2008 were washed with deionized water and the plant components separated into leaves, flowers, and stems, and then lyophilized and homogenized by grinding. Soil samples collected in 2007 and 2008 were lyophilized and then homogenized by grinding. Chemical analysis
Both plant and soil samples were analyzed for heavy metal (Cd, Cr, Cu, Ni, Pb, and Zn) and metalloid (As, Se, and Sb) content. In the soil samples, the acid-leachable fractions of soil under the plants were considered. Heavy metal and metalloids from the acidleachable soil fractions were analyzed from extracts obtained by 0.5 h extraction with 2 mol L1 HCl at 80 8C [17]. The 1.50 g of the plant components were mineralized in 14.0 mL 65% HNO3 and 1.0 mL 30% H2O2 at 98 8C for a 20-h extraction period and filtered through a medium-size qualitative filter (rinsed with 200 mL of distilled water) [21]. The mineralization of the samples was provided in triplicates. Metal concentrations were measured by using flame atomic absorption spectrometry (AAS). The following determination conditions were applied (the background correction with a deuterium lamp has been used): Cr: wavelength 357.9 nm, slit 0.2 nm; Cu: wavelength 324.8 nm, slit 0.5 nm; Ni: wavelength 232.0 nm, slit 0.2 nm; Cd: wavelength 228.8 nm, slit 0.5 nm; Pb: wavelength 217.0 nm, slit 1.0 nm; and Zn: wavelength 213.9 nm, slit 1.0 nm. The detection limits were at the level of 0.1 mg kg1, and the analytical range to 100 mg kg1 for all of the metals. Metalloids were determined by AAS with hydride generation (HGAAS); the following determination conditions were applied (no background correction): As: wavelength 193.7 nm, slit 0.5 nm; Sb: wavelength 217.6 nm, slit 0.2 nm; and Se: wavelength 196.0 nm, slit 1.0 nm; the detection limits were at the level of 1 mg kg1 and an analytical range to 100 mg kg1 for As, Sb, and Se. In the case of the higher element concentration, the samples have been appropriately diluted. The correlation coefficients obtained for calibration curves were higher than 0.9950. The uncertainty of the entire analytical process did not exceed 20% for all determined
Table 1. The list of sampling sites (south Thailand, the coast of the Andamanian Sea) for post tsunami soil analysis and bioaccumulation factor determination Sampling site
Location
Latitude N
Longitude E
2 3 4 5 6 Reference site
Bang Mor Kho Koh Khao Kho Kho Khan Kho Kho Khan Kho Kho Khan Kho Kho Khan Kho Khao CS
088490 15.900 098000 01.300 088560 00.800 088530 07.000 088540 09.300 088520 09.900 088490 57.400
988160 03.500 988150 08.100 988150 10.500 988150 14.400 988150 01.700 988160 04.200 988160 20.200
1 2 3 4 5 Reference site
Patong Beach Bang Mor Kho Kho Khan Kho Kho Khan Kho Kho Khan Ban Bang Niang
078520 55.200 088500 00.700 088530 03.100 098000 47.400 088550 04.100 088400 56.800
988170 18.900 988150 58.500 988150 55.100 988150 23.400 988140 59.400 988140 35.600
2007 year 1
2008 year
254
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L. Kozak et al.
elements. Traceability studies have been provided by certified reference materials analysis and by the method of standard addition. To determine the relationship between the individual element concentrations in the soil and plant components, a bioaccumulation factor (BAF) was calculated, using the following formula: BAF ¼ Cp=Cs
ð1Þ
where BAF is the bioaccumulation factor, Cp is the concentration of a given element in the plant or plant component (flower, leaf, stem), and Cs is the concentration of the given element in the soil. RESULTS
Heavy metals and metalloids in soil and whole plants
Concentrations of heavy metals and metalloids in soil and plant samples collected in 2007 are listed in Table 2. The median concentrations of Pb, Zn, and Cu among heavy metals and As among metalloids were the highest in both the soil and plant samples. The median concentrations of metals in the soil decreased in the following order: Pb > Zn > Cr > Cu > Cd > Ni, whereas the median concentrations of metals in plants decreased: Zn > Cu > Pb > Cr > Cd > Ni. The median concentrations of Cd, Pb, and Ni were similar in soil and plants, and median concentrations of Cr, Cu, and Zn were higher in plants. The median concentrations of Pb, Zn, and As in the soil were 11.5 mg kg1, 7.2 mg kg1, and 684 mg kg1, respectively, and in plants 11.0 mg kg1, 28.0 mg kg1, and 501 mg kg1, respectively; both were higher than in the reference site. The concentrations of metals and metalloids, however, did not differ significantly (p < 0.05) between sampling sites and the reference site for both soil and plant samples (based on the results of the runs test [Wald–Wolfowitz test] and maximum normed residual test [Grubbs test]). Distribution of heavy metals in different plant parts
Concentrations of heavy metals and metalloids in the soil and plant samples collected in 2008 are given in Table 3. The median concentrations of Pb and Zn (6.9 mg kg1, 4.4 mg kg1, respectively) among heavy metals and As (906 mg kg1) among metalloids were the highest in the soil samples. The median concentrations of metals in the soil decreased in the following order: Pb > Zn > > Ni > Cr > Cu > Cd.
The median concentration of As in the soil was higher in sampling sites in comparison with the reference site; however, concentrations of most of the heavy metals and metalloids we investigated did not differ significantly (based on the results of the runs test [Wald–Wolfowitz test] and maximum normed residual test [Grubbs test]) among sampling sites and between sampling sites and the reference site. Concentrations of heavy metals and metalloids varied in the different plant components of Ipomoea pes-caprae. Heavy metal concentrations were higher in the flowers compared with concentrations found in leaves and stems. The highest medians of metal concentrations for flowers, leaves, and stems (282 mg kg1, 10.9 mg kg1, and 28.0 mg kg1, respectively) were observed for Zn. The median concentrations of metals decreased in the following order: Zn > Ni > Pb > Cr > Cu > Cd in flowers, Zn > Cr > Ni > Pb > Cu > Cd in leaves, and Zn > Ni > Cr > Cu > Pb > Cd in stems. The highest median concentration of As was observed in leaves. The median concentrations of all metals were higher in flowers than in soil from the sampling sites, whereas the median concentrations of Cd and Pb were lower in leaves, and stems in comparison with concentrations in soil. The median concentrations of the rest of the metals we investigated were higher in the leaves, and stems than the concentrations found in the soil. Concentrations of heavy metals and metalloids in flowers, stems, and leaves did not differ significantly among sampling sites, nor between sampling sites and the reference site. Accumulation of heavy metals and metalloids in Ipomoea pescaprae
The BAFs for Ipomoea pes-caprae collected in 2007 indicated that it was most efficient in taking up Cu followed by Zn, and finally Sb. In addition, BAFs of As, Cr, and Ni were higher, and that of Cd was lower in most of the sampling sites affected by the tsunami in comparison with the reference site that was not impacted by the tsunami. The BAFs of the other metals reached similar values from these locations (Table 4). The 2008 analysis of heavy metals and metalloids within the plant components from all sites indicated that the uptake of Cr, Cu, Ni, Zn, Pb, and Cd was highest in the flowers followed by leaves, and stems, respectively. The BAFs for Cu and Zn was higher in stems than in the leaves. Higher BAFs for Ni, Cr, Zn, and Pb were in all plant components at most of the sites affected by the tsunami. The uptake of Cd and Cu was greater at the reference site (Table 5). The BAFs of Se and As varied among the plant components and at the sampling locations, but generally was higher at the reference site (Table 5).
Table 2. Concentrations (for dry mass) of heavy metals and metalloids in plant and soil in 2007a Site 1
Heavy metals Cd (mg kg–1) Pb (mg kg–1) Ni (mg kg–1) Cr (mg kg–1) Cu (mg kg–1) Zn (mg kg–1) Metalloids Se (mg kg–1) As (mg kg–1) Sb (mg kg–1) a
Site 2
Site 3
Site 4
Site 5
Site 6
Reference site
Soil
Plant
Soil
Plant
Soil
Plant
Soil
Plant
Soil
Plant
Soil
Plant
Soil
Plant
3.3 29 0.6 6.7 1.9 11
1.5 13 0.2 0.4 14 38
2.1 17 0.7 3.2 1.6 11
1.3 12 0.8 7.3 12 31
0.7 8.0 0.4 1.9 1.0 7.7
1.2 11 0.4 8.2 3.1 20
0.7 9.0 0.5 3.2 1.3 5.5
1.5 11 0.6 15 11 32
1.5 14 0.6 3.0 1.0 6.8
1.1 7.7 0.3 3.9 5.4 23
0.5 7.2 0.1 1.3 0.9 5.1
1.2 9.9 0.3 3.0 13 25
0.2 7.3 0.8 3.6 1.8 6.0
1.2 8.3 0.5 5.9 19 22
61 915 46
41 476 102
41 879 39
30 657 93
24 472 25
25 526 91
52 586 33
39 393 104
36 782 35
36 218 97
31 499 25
33 1591 97
42 522 33
30 230 109
n ¼ 3, (uncertainty below 20%).
Bioaccumulation by Ipomoea from tsunami impacted areas
Environ Toxicol Chem 34, 2015
255
Table 3. Concentrations (for dry mass) of heavy metals and metalloids in plant and soil in 2008a Site 1 So
F
L
Site 2 St
Heavy metals (mg kg–1) Cd 0.3 13 0.9 0.8 Pb 6.9 67 3.4 2.7 Ni 0.9 162 4.7 3.8 Cr 1.0 165 3.7 2.4 Cu 804 35 9.4 15 Zn 55 282 10.9 28 Metalloids (mg kg–1) Se 63
