Marine Pollution Bulletin xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul
Baseline
Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea Jinhyung Cho a, Sangmin Hyun b,⇑, J.-H. Han c, Suhyun Kim d, Dong-Hyeok Shin a a
Maritime Security Research Center, Korea Institute of Ocean Science and Technology (KIOST), 787 Hean-ro Ansan, 426-744, South Korea Marine Geology and Geophysics Division, KIOST, 787 Hean-ro Ansan, 426-744, South Korea c Korea Basic Science Institute (KBSI), 169-148 Gwahak-ro, Yuseong-gu, Daejeon 305-806, South Korea d Neo Environmental Business Co. (NeoEnBiz), A-1306 Dodang-dong, Wonmi-gu, Gyeonggi-do 175-209, South Korea b
a r t i c l e
i n f o
Article history: Available online xxxx Keywords: Historical trend Pollution Heavy metal PCA Masan Bay
a b s t r a c t The spatiotemporal distribution and their mass accumulation rate (MAR) of heavy metals were investigated to evaluate the time-dependent historical trends of heavy metal concentration. The three short cores used for this study were collected from the catchment area (MS-PC5, 60 cm length), the central part (MS-PC4, 40 cm length) and the offshore (MS-PC2, 60 cm length) of the Masan Bay, Korea. The concentration of heavy metals (Co, Ni, Cu, Zn, Cr and Pb) in catchment area is as much as 1.5–2 times higher than central part of the Bay, and about 2 times higher than offshore area approximately. In particular, MAR of metals (Cu, Zn and Pb) show clear spatiotemporal variation, so that MAR’s of heavy metal may provide more accurate information in evaluating the degree of pollution. Temporally, the heavy metal concentration had been increased since the late 1970s, but it seems to decrease again since the 2004 yr in catchment area. This may came from concentrated efforts for the government to reduce industrial waste release. Ó 2015 Elsevier Ltd. All rights reserved.
A large amount of industrial effluents usually had been brought significant and rapid environmental degradation, in particular in coastal and bay environments. Consequently, ecosystem surrounded in these circumstances might be destroyed and threaten all kind of living things including human being (Forstner and Wittman, 1981). These sever circumstances, therefore led to concentrated effort to lessen the pollution degree. Within this point of view, it is necessary to evaluate exact tendency of pollution and/or natural background of heavy metal concentration. Numerous studies concerning the heavy metal pollution and its related environmental changes have been conducted in coastal and bay environments in various regions (Feng et al., 2004; Hyun et al., 2007; Niencheski et al., 2014; Wu et al., 2014). Masan Bay shows one of typical bay system, reserve various characteristics such as high influx of organic matters and metals (Hong et al., 2003; Hyun et al., 2007; Lim et al., 2012), and very sluggish ventilation compared to off shore and seasonal variations of oceanographic environments (Choi, 1993). Also, as most of other bays, environmental deterioration of Masan Bay was strongly associated with benthic environment, benthic animals’ habitation (Choi ⇑ Corresponding author. Tel.: +81 31 400 7838. E-mail addresses: [email protected] (J. Cho), [email protected] (S. Hyun), hanjh@kbsi. re.kr (J.-H. Han), [email protected] (S. Kim), [email protected] (D.-H. Shin).
et al., 2005). Masan Bay borders one of the most concentrated industrial areas of Korea and surrounded by the cities of Masan and Changwon, where large industrial complexes have been built since 1960 (Fig. 1). Therefore, serious environmental pollution by heavy metal and organic pollutant in Masan Bay has been reported previously (e.g., Hong et al., 2003; Jeong et al., 2006; Hyun et al., 2007; Lim et al., 2012). However, it has not been attention to lessen the influx of pollutant materials until the 1990s in Korea. This is due to the government policy that industry priority rather than environmental protection. Large amounts of discharge in industrial waste may cause significant and rapid environmental changes results in environmental deterioration in this bay (Jeong et al., 2006; Hyun et al., 2007; Lim et al., 2012). However, synthesized studies in terms of spatiotemporal variations of heavy metal pollution are not enough to future expectation and prevention. In particular, previous studies had been accomplished only by metal concentration, not by time-dependent metal mass accumulation rate (MAR). The aim of this research is to evaluate the time-dependent spatiotemporal changes of heavy metals, and also investigate historical records from three sedimentary core sediments. Masan Bay, located at the southern coast of Korea, is characterized by its semi-enclosed, elongated geographic surroundings. The cities of Masan and Changwon are nearby, representative
http://dx.doi.org/10.1016/j.marpolbul.2015.03.034 0025-326X/Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Cho, J., et al. Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea. Mar. Pollut. Bull. (2015), http://dx.doi.org/10.1016/j.marpolbul.2015.03.034
2
J. Cho et al. / Marine Pollution Bulletin xxx (2015) xxx–xxx
Fig. 1. Sampling locations of gravity core sediments from the Masan Bay, Korea. Note that those of Masan, Jinhae and Changwon cities surround the Masan Bay. DST is Dukdong Sewage treatment plant.
industrial complex in Korea (Fig. 1). Masan Bay has been used important sea port since the 1930s, and elongate tidal flats had already been converted into artificial container, industrial complexes, and development is still ongoing. Sediment core samples were collected in Masan Bay using a potable gravity piston core in 2006 yr (Fig. 1; Table 1). After collection, the core samples were split into two parts, and the sampling was conducted from the archived half. All the samples for grainsize, organic matter and metal concentration were dried at 60 °C for overnight and crashed by agate mortar in laboratory condition. About 10 g sediment was run for grain size at the Korea Institute of Ocean Science and Technology (KIOST). For the metal analysis, powdered samples were digested by a mixture of HNO3, HF, and HClO4 using Atomic Absorption Spectrometer (AAS) at the KIOST. Also, total carbon content was determined by the direct measurement by CHNS analyzer (EA 1112). The organic carbon was determined by the subtraction of inorganic carbon from total carbon (TC). Duplicate analysis showed that all analytical errors were less than 5% for each element. In particular, the 210Pb sediment accumulation rates were determined by an independent method for calculating sedimentation rates and 137Cs chronology. Dry sediment samples (15–20 g) were loaded into a cylindrical vial (5 cm i.d.), sealed
and counted over 24 h. 137Cs and 210Pb were determined using the 661.6 and 46.5 keV photopeaks, respectively. The samples were counted again at least 30 days after sealing and the 226Ra content was estimated from the 214Bi (609.3 keV) and 214Pb (352.0 keV) photopeaks (Gilmore and Hemingway, 1995). The excess 210Pb were determined as the difference between total 210Pb and 226Ra activities (Radakovitch et al., 1999). Also, 137Cs were measured by its emission at 662 keV. The absolute efficiencies of the detectors were determined using calibrated sources and sediment samples of known activity. The mass accumulation rate (MAR) of any metals was calculated as follows; some element concentration (lg/g) dry bulk density (cm2) linear sedimentation rate (cm/ year). As each coring places are thought to have different oceanographic conditions such as productivity changes through the seasonal variation, different current and circulation systems, sedimentary environment of the each place might be expected different. Also, because of the accumulation rate of heavy metal is strongly associated not only with the influx of metal but also benthic environment such as sedimentation rate and sediment grain size, the metal concentration of three sites may be different each other. This oceanographic difference among site may provide valuable insight into concentrations of heavy metal accumulation.
Please cite this article in press as: Cho, J., et al. Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea. Mar. Pollut. Bull. (2015), http://dx.doi.org/10.1016/j.marpolbul.2015.03.034
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J. Cho et al. / Marine Pollution Bulletin xxx (2015) xxx–xxx Table 1 Summary of various data in three cores.
a b
BGa
MS-PC2 (60 cm) Range
TOC (%) CaCO3 (%) C/N Mz (phi) Cr (lg/g)
90
1.0–1.6 2.0–5.5 8.8–12.6 7.3–7.7 53.5–144.9
Ni (lg/g)
68
24.4–64.0
Cu (lg/g)
45
14.8–48.5
Zn (lg/g)
95
105.2–233.0
Pb (lg/g)
20
15.7–39.9
EFb
0.73–1.23 (1.01) 0.89–1.08 (0.99) 0.95–1.49 (1.17) 0.90–1.44 (1.15) 0.75–1.89 (1.27)
MS-PC4 (40 cm) Range 1.1–2.9 0.0–8.9 6.8–12.6 7.7–10.3 0.9–77.9 11.4–31.6 15.2–72.2 119.2–318.8 22.2–64.1
EF
MS-PC5 (60 cm) Range
EF
0.8–1.6 0.0–15.3 4.1–15.3 0.01–1.21 (0.89) 0.4–1.1 (0.91) 1.0–3.7 (2.30) 0.9–2.4 (1.58) 1.0–2.8 (1.80)
42.8–81.7 10.7–27.6 10.5–78.0 50.1–310.2 5.5–68.8
0.74–1.41 (1.05) 0.45–1.16 (0.96) 0.39–2.88 (1.48) 0.44–2.72 (1.36) 0.31–3.83 (1.66)
BG is background concentration value of earth’s crust (Turekian and Wedepohl, 1961). EF is enrichment factors and (average).
The surface sediment characteristics in Masan Bay in terms of grain size distribution were investigated in previous works (Hyun et al., 2007), and they revealed that the surface sediment is mostly composed by silt to clay size materials over the entire areas. Considering this previous results, the core sediment, in particular upper part of the core sediment reflect recent sediment that has been deposited by recent sedimentation processes without any disturbances. In current study, the mean grain sizes (Mz) of two cores were variable (Table 1). The Mz varies from about 7–10 phi suggest that very fine silt to clay size particles were predominated throughout the two core. The average content of total organic carbon (TOC) and carbonate in three core sediments were shown in Table 1. The vertical TOC levels were highly variable, ranging from 0.8% to 2.9%, generally. Higher TOC levels were observed in fine sediments, whereas lower TOC levels were observed in more coarse sediments. This grain-size dependent variation in organic carbon concentrations were coincides well with previous studies (Salomons and Forstner, 1984). However, Mz is slightly coarse in core MS-PC2, and it may be expected very fine in catchment area
(Woo et al., 2003; Hyun et al., 2007). Based on this grain-size parameter, the core sediment does not contain coarse sand material which is thought to be deposited under high hydrodynamic condition such as storm surge. Even though Mz in MS-PC2 is slightly coarser than those of MS-PC4, the TOC content is mostly similar between two cores. This unusual case is attributed either very low range of grain-size variation or specific feature of core sediment of Masan Bay. The C/N ratio of organic matter exceeded 10 in several samples in Core MS-PC5. In general, the C/N ratio of organic matter indicates the source of the organic matter. When the organic matter C/N ratio is greater than 10, it is thought to have a terrigenous source, and ratios of 5–10 are considered to derive from marine sources (Stein, 1991). The C/N ratios of organic matter in the study area suggest that terrigenous organic matter was supplied from the neighboring landmass. Based on the previous work that stable carbon isotope of the organic matter was less than 26‰ in surface sediment samples, implying that a large amount of organic matter were transported from neighboring land area (Hyun et al., 2011).
Fig. 2. Profiles of excess 210Pb and 137Cs activities with sedimentation rate. Excess 210Pb were determined by subtracting the 226Ra activities from the total 210Pb activities. The sedimentation rate was derived from the linear relationship between 210Pb activities and depth of the cores (R2 is > 0.8 in this study).
Please cite this article in press as: Cho, J., et al. Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea. Mar. Pollut. Bull. (2015), http://dx.doi.org/10.1016/j.marpolbul.2015.03.034
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J. Cho et al. / Marine Pollution Bulletin xxx (2015) xxx–xxx
Fig. 3. Historical trends in heavy metals concentration (Cu, Pb and Zn) and their mass accumulation rate (MAR). Calendar age was calculated based on the decay of excess 210 Pb. Note that the elemental MARs were drown with the same scale. Abrupt increase was clear in core MS-PC5 at around 1970s.
Therefore, higher C/N ratios recognized in core MS-PC5, could be confirmed that some part of terrestrial material could be supplied from nearby land areas. The carbonate content of the surface sediments varied from 0.0% to 15.3% (Table 1). In general, carbonate content is controlled by the input of terrigenous materials (dilution), productivity levels, and carbonate dissolution (Stein, 1991). This value of carbonate content occurred in three cores are generally lower than those of open ocean where the carbonate content reaches several tens of percentage if the water depth lies above the carbonate compensation depth (CCD). Some anoxic bottom condition was reported in previous work (Choi et al., 2005; Hyun et al., 2007), therefore probably carbonate dissolution could have occurred.
The extremely variable carbonate levels observed in this study could reflect the anoxic bottom conditions or the presence of shell fragments in the near-shore sediments. However, generally lower carbonate content in three cores could not be evaluated in present study, but it could not exclude that some part of carbonate could have subjected to dissolution due to the extremely depleted oxygen content in catchment area. The sedimentation rate was calculated on the basis of 210Pb data as shown in Fig. 2. In MS-PC2 and MS-PC5, the sedimentation rate was very similar, they are 0.44 ± 0.3 cm/yr and 0.41 ± 0.11 cm/yr, respectively. These sedimentation rates were slighter higher than previous work (0.33 cm/yr) of Woo et al. (2003). In MS-PC4, however the sedimentation rate is 0.28 ± 0.1 cm/yr, showing similar
Please cite this article in press as: Cho, J., et al. Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea. Mar. Pollut. Bull. (2015), http://dx.doi.org/10.1016/j.marpolbul.2015.03.034
J. Cho et al. / Marine Pollution Bulletin xxx (2015) xxx–xxx
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Fig. 4. Principal Component Analysis (PCA) of loading plots of various components in three cores. Most metals in core MS-PC5 were concentrated together, whereas distribution patterns in MS-PC2 and MS-PC4 do not show the similar pattern.
with the report in Masan Bay (Woo et al., 2003). Entirely, sedimentation rate of the current study do not show any higher deviation, implying reasonable measurement. As shown in Fig. 2, liner regression lines of the three 210Pb data point shows high correlation coefficient. The ranges of heavy metals concentration (Cr, Ni, Cu, Zn and Pb) in three cores were illustrated in Table 1. Generally, elemental concentration seems to higher toward to core top, recent year with a boundary of 1970s, in which higher concentration and approximately correspond to the timing of the initiation of vigorous anthropogenic activity. Also, the enrichment factor (values) of heavy metal concentration shows spatial variation; higher enrichment values in catchment core and vise versa (Table. 1). In case of MS-PC5, the enrichment factor is as much as 1.5–2 times higher than those of MS-PC2, which is located in offshore area, and not being influenced from anthropogenic contribution. In earlier studies, Feng et al. (2004) and Zhang and Liu (2002) used the enrichment factor (EF) as an indicator of the degree of pollution or of environmental contamination as follows. Enrichment factor (EF) = {(X/Al)sample/(X/Al)mean sediment}. In this formula, (X/Al)sample is the metal to Al in the samples of interest, and (X/Al)mean sediment is the natural background value of the metal to Al ratio (Rubio et al., 2000). Values of EF between 0.5 and 1.5 were interpreted as indicating that the element may be associated with crustal material or natural weathering processes. Values of EF greater than 1.5 suggested that a significant portion of the metal was associated with non-crustal material and/or weathering processes, i.e., the metal was supplied by other sources. As suggested by Zhang and Liu (2002), the presence of EF values greater than 1.5 at a large number of sampling stations indicates metal accumulation from anthropogenic sources.
The content and EF values of Cr, Ni, Cu, Zn and Pb and their MAR’ are illustrated in Fig. 3 and Table 1. Most EF values for five metals were ranged from 0.01 to 3.83. The EF values of samples with values < 1 were considered not to have accumulated the element, and samples with values > 1 were considered to have accumulated the element. In other words, elemental accumulation varied greatly, indicating that accumulation resulted from a combination of natural and anthropogenic sources. Thus accumulation above the natural value would be attributed to pollutant effects. In three cores, metal concentration showed increasing tendency since the 1970s. In particular, MARs of Cu, Pb and Zn in MS-PC5 shows synchronized pattern; abrupt increase since the 1970s and decline around 2006 yr (Fig. 3), indicating significant accumulation. Therefore, all areas were not polluted significantly in terms of heavy metal accumulation during before the 1970s, whereas this starts to increase since the 1970s. The upper parts of sediments in core MS-PC5 were polluted significantly, indicating severe pollution since the late 1970s. As a multivariate statistical technique, Principal Component Analysis (PCA) has been extensively used to identify patterns of environmental contamination (e.g., Szefer and Kaliszan, 1993; Rubio et al., 2000; Shin and Lam, 2001). Especially, Vogt (1990) interpreted sediment chemical composition and pollution sources based on a regression model derived from PCA results. Therefore, we applied PCA to interpret the variation in metal concentrations with sampling location in this study. In the case of the surface sediment in Masan Bay, metal concentrations could be divided into four groups: aluminosilicate-bound elements, carbonatebound elements, redox-sensitive elements, and anthropogenic elements (Hyun et al., 2007). In particular, some heavy metal such as Co, Cr, Ni and Ni are strongly associated each other
Please cite this article in press as: Cho, J., et al. Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea. Mar. Pollut. Bull. (2015), http://dx.doi.org/10.1016/j.marpolbul.2015.03.034
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J. Cho et al. / Marine Pollution Bulletin xxx (2015) xxx–xxx
and thus interpreted as end member of terrigenous and anthropogenic elements. In this present study, loading plots for the three cores are quite different from the surface sediment of previous work of Hyun et al. (2007). It seems that most elemental distribution in two cores (MSPC2 and MS-PC4) are scattered through all areas with one cluster of ON, OC indicating that most of these element is not constrained by one factor only. Instead, they were associated with various factors. Considering that elemental concentration is mainly associated with previous mentioned four factors, these wide ranged scattering imply that the characteristics of each elements are associated with one or two factors of four (Fig. 4). The organic components of OC and ON in these two core sediment, however seems to shows outlier, potentially deviated from whole component, implying different PCA component. In case of MS-PC5, however all components seems to be divided into three group. The first one is carbonate matrix, the second is organic carbon and nitrogen, and the last group is remaining heavy metal group, which can be attributed to anthropogenic sources and terrestrial sources potentially (Fig. 4). In Masan Bay core sediments, metal concentration is characterized by the spatiotemporal variation. Entirely, metal concentration seems to be increasing toward the catchment area of Masan Bay. In offshore area, EF and MAR do not show larger fluctuation, both EF and MAR are less than 2, and the MARs of Pb and Zn are less than 20 and 80 lg/cm2yr, respectively. These values were quite lower than those of MS-PC4 and MS-PC5. Temporally, EF and MARs of Cu, Pb and Zn start to increase from around the 1940s and this timing is also coincident with the timing of the initiation of industrial activities in Masan Bay. However, mostly high accumulation rate seems to be started in 1970s in central and catchment core sites. Most increased EF and MARs, however, were recognized in catchment site, showing over than 3 in EF and over than 140 lg/cm2yr in case of Zn. This increased value is much higher than that of offshore values. Slight decrease of EF and MAR of Zn and Pb were recognized in catchment site since the 2004s, but it is hard to evaluate the cause of this decreasing tendency. Concentrated efforts to lessen the metal effluences from government could be one reason to be considered. However, for more accurate evaluation, continuous geochemical research is necessary. Acknowledgements The authors thank to anonymous reviewers for their critical reading of original document. This study was conducted by the support from the grant of KIOST’s project entitled ‘‘Environmental Changes in the Seomjin River Estuary’’ (PE99334). KIODP project (PM58300) funded by ‘‘Ministry of Ocean and Fisheries’’ supported this research in part.
References Choi, W.-J., 1993. Numerical Simulation of the Formation of Oxygen Deficient Water Mass in Jinhae Bay. Ph D Thesis. National Fisheries Univ. Pusan, pp. 97. Choi, J.-W., Seo, J.-Y., Lee, C.-H., Ryu, T.-K., Sung, C.-G., Han, G.-M., Hyun, S., 2005. Spatial distribution patterns of Macrobenthic communities during winter and summer in the Masan Bay Spatial Management Area, Southern coast of Korea. Ocean Polar Res. 27, 381–395. Feng, H., Han, X., Zhang, W., Yu, L., 2004. A preliminary study of heavy metal contamination in Yangtze River intertidal zone due to urbanization. Mar. Pollut. Bull. 49, 910–915. Forstner, U., Wittman, G.T.W., 1981. Metal Pollution in the Aquatic Environment. Springer Verlag, Berlin, pp. 486. Gilmore, G., Hemingway, J., 1995. Practical Gamma-Ray Spectrometry. Wiley, Chichester. Hong, S.H., Yim, U.H., Shim, W.J., Oh, J.R., Lee, I.S., 2003. Horizontal and vertical distribution of PCBs and chlorinated pesticides in sediments from Masan Bay, Korea. Mar. Pollut. Bull. 46, 244–253. Hyun, S., Lee, C.-H., Lee, T., Choi, J.-W., 2007. Anthropogenic contributions to heavy metal distributions in the surface sediments of Masan Bay, Korea. Mar. Pollut. Bull. 54, 1059–1068. Hyun, S., Lee, T., Jung, S.-K., 2011. Contents and stable isotopic composition of organic carbon and total nitrogen in the surface sediment of two coastal bays in Korea. Ocean Sci. J. 46, 289–297. Jeong, K.S., Cho, J.H., Lee, J.H., Kim, K.H., 2006. Accumulation history of anthropogenic heavy metals (Cu, Zn, and Pb) in Masan May sediments, southeastern Korea: a role of chemical front in the water column. Geosci. J. 10, 445–455. Lim, D.I., Jung, H.S., Kim, K.T., Sin, H.H., Jung, S.W., 2012. Sedimentary records of metal contamination and eutrophication in Jinhae-Masan Bay, Korea. Mar. Pollut. Bull. 64, 2542–2548. Niencheski, L.F., Moore, W.S., Windom, H.L., 2014. History of human activity in coastal southern Brazil from sediment. Mar. Pollut. Bull. 78, 209–212. Radakovitch, O., Charmasson, S., Arnaud, M., Bouisset, P., 1999. 210Pb and Cesium accumulation in the Rhone Delta sediments. Estuar. Coast. Shelf Sci. 48, 77–92. Rubio, B., Nombela, M.A., Vilas, F., 2000. Geochemistry of major and tracer elements in sediments of the Ria de Vigo (NW Spain): an assessment of metal pollution. Mar. Pollut. Bull. 40, 968–980. Salomons, W., Forstner, U., 1984. Metal in the Hydrocycle. Springer-Verlag, Berlin, pp. 349. Shin, P.K.S., Lam, W.K.C., 2001. Development of a marine sediment pollution index. Environ. Pollut. 113, 281–291. Stein, R., 1991. Accumulation of Organic Carbon in Marine Sediment. Lecture Notes in Earth Science. Springer-Verlag, Berlin, pp. 217. Szefer, P., Kaliszan, R., 1993. Distribution of elements in sediment cores of the Southern Baltic from the point of view of principal component analysis. Studia 1 Materialy Oceanogeczne NR 64. Mar. Pollut. 1, 95–102. Turekian, K.K., Wedepohl, K.H., 1961. Distribution of the elements in some major units of the earth’s crust. Bull. Geol. Soc. Am. 72, 175–192. Vogt, N.B., 1990. Multivariate ecotoxicological mapping of the relationships between sediment chemical composition and fauna diversity. Sci. Total Environ. 90, 149–161. Woo, H.-J., Cho, J.-H., Jeong, K.-S., Chung, C.-S., Kwon, S.-J., Park, S.-M., 2003. Pollution history of the Masan Bay, southeast Korea, from heavy metals and foraminifera in the subsurface sediments. J. Korean Earth Sci. Soc. 24, 635–649 (in Korean with English abstract). Wu, Guanghong, Shang, Jingmin, Pan, Ling, Wang, Zhongling, 2014. Heavy metals in surface sediments from nine estuaries along the coast of Bohai Bay, Northern China. Mar. Pollut. Bull. 82, 192–200. Zhang, J., Liu, C.L., 2002. Riverine composition and estuarine geochemistry of particulate metals in China weathering features, anthropogenic impact and chemical fluxes. Estuar. Coast. Shelf Sci. 54, 1051–1070.
Please cite this article in press as: Cho, J., et al. Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea. Mar. Pollut. Bull. (2015), http://dx.doi.org/10.1016/j.marpolbul.2015.03.034
Contents lists available at ScienceDirect
Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul
Baseline
Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea Jinhyung Cho a, Sangmin Hyun b,⇑, J.-H. Han c, Suhyun Kim d, Dong-Hyeok Shin a a
Maritime Security Research Center, Korea Institute of Ocean Science and Technology (KIOST), 787 Hean-ro Ansan, 426-744, South Korea Marine Geology and Geophysics Division, KIOST, 787 Hean-ro Ansan, 426-744, South Korea c Korea Basic Science Institute (KBSI), 169-148 Gwahak-ro, Yuseong-gu, Daejeon 305-806, South Korea d Neo Environmental Business Co. (NeoEnBiz), A-1306 Dodang-dong, Wonmi-gu, Gyeonggi-do 175-209, South Korea b
a r t i c l e
i n f o
Article history: Available online xxxx Keywords: Historical trend Pollution Heavy metal PCA Masan Bay
a b s t r a c t The spatiotemporal distribution and their mass accumulation rate (MAR) of heavy metals were investigated to evaluate the time-dependent historical trends of heavy metal concentration. The three short cores used for this study were collected from the catchment area (MS-PC5, 60 cm length), the central part (MS-PC4, 40 cm length) and the offshore (MS-PC2, 60 cm length) of the Masan Bay, Korea. The concentration of heavy metals (Co, Ni, Cu, Zn, Cr and Pb) in catchment area is as much as 1.5–2 times higher than central part of the Bay, and about 2 times higher than offshore area approximately. In particular, MAR of metals (Cu, Zn and Pb) show clear spatiotemporal variation, so that MAR’s of heavy metal may provide more accurate information in evaluating the degree of pollution. Temporally, the heavy metal concentration had been increased since the late 1970s, but it seems to decrease again since the 2004 yr in catchment area. This may came from concentrated efforts for the government to reduce industrial waste release. Ó 2015 Elsevier Ltd. All rights reserved.
A large amount of industrial effluents usually had been brought significant and rapid environmental degradation, in particular in coastal and bay environments. Consequently, ecosystem surrounded in these circumstances might be destroyed and threaten all kind of living things including human being (Forstner and Wittman, 1981). These sever circumstances, therefore led to concentrated effort to lessen the pollution degree. Within this point of view, it is necessary to evaluate exact tendency of pollution and/or natural background of heavy metal concentration. Numerous studies concerning the heavy metal pollution and its related environmental changes have been conducted in coastal and bay environments in various regions (Feng et al., 2004; Hyun et al., 2007; Niencheski et al., 2014; Wu et al., 2014). Masan Bay shows one of typical bay system, reserve various characteristics such as high influx of organic matters and metals (Hong et al., 2003; Hyun et al., 2007; Lim et al., 2012), and very sluggish ventilation compared to off shore and seasonal variations of oceanographic environments (Choi, 1993). Also, as most of other bays, environmental deterioration of Masan Bay was strongly associated with benthic environment, benthic animals’ habitation (Choi ⇑ Corresponding author. Tel.: +81 31 400 7838. E-mail addresses: [email protected] (J. Cho), [email protected] (S. Hyun), hanjh@kbsi. re.kr (J.-H. Han), [email protected] (S. Kim), [email protected] (D.-H. Shin).
et al., 2005). Masan Bay borders one of the most concentrated industrial areas of Korea and surrounded by the cities of Masan and Changwon, where large industrial complexes have been built since 1960 (Fig. 1). Therefore, serious environmental pollution by heavy metal and organic pollutant in Masan Bay has been reported previously (e.g., Hong et al., 2003; Jeong et al., 2006; Hyun et al., 2007; Lim et al., 2012). However, it has not been attention to lessen the influx of pollutant materials until the 1990s in Korea. This is due to the government policy that industry priority rather than environmental protection. Large amounts of discharge in industrial waste may cause significant and rapid environmental changes results in environmental deterioration in this bay (Jeong et al., 2006; Hyun et al., 2007; Lim et al., 2012). However, synthesized studies in terms of spatiotemporal variations of heavy metal pollution are not enough to future expectation and prevention. In particular, previous studies had been accomplished only by metal concentration, not by time-dependent metal mass accumulation rate (MAR). The aim of this research is to evaluate the time-dependent spatiotemporal changes of heavy metals, and also investigate historical records from three sedimentary core sediments. Masan Bay, located at the southern coast of Korea, is characterized by its semi-enclosed, elongated geographic surroundings. The cities of Masan and Changwon are nearby, representative
http://dx.doi.org/10.1016/j.marpolbul.2015.03.034 0025-326X/Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Cho, J., et al. Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea. Mar. Pollut. Bull. (2015), http://dx.doi.org/10.1016/j.marpolbul.2015.03.034
2
J. Cho et al. / Marine Pollution Bulletin xxx (2015) xxx–xxx
Fig. 1. Sampling locations of gravity core sediments from the Masan Bay, Korea. Note that those of Masan, Jinhae and Changwon cities surround the Masan Bay. DST is Dukdong Sewage treatment plant.
industrial complex in Korea (Fig. 1). Masan Bay has been used important sea port since the 1930s, and elongate tidal flats had already been converted into artificial container, industrial complexes, and development is still ongoing. Sediment core samples were collected in Masan Bay using a potable gravity piston core in 2006 yr (Fig. 1; Table 1). After collection, the core samples were split into two parts, and the sampling was conducted from the archived half. All the samples for grainsize, organic matter and metal concentration were dried at 60 °C for overnight and crashed by agate mortar in laboratory condition. About 10 g sediment was run for grain size at the Korea Institute of Ocean Science and Technology (KIOST). For the metal analysis, powdered samples were digested by a mixture of HNO3, HF, and HClO4 using Atomic Absorption Spectrometer (AAS) at the KIOST. Also, total carbon content was determined by the direct measurement by CHNS analyzer (EA 1112). The organic carbon was determined by the subtraction of inorganic carbon from total carbon (TC). Duplicate analysis showed that all analytical errors were less than 5% for each element. In particular, the 210Pb sediment accumulation rates were determined by an independent method for calculating sedimentation rates and 137Cs chronology. Dry sediment samples (15–20 g) were loaded into a cylindrical vial (5 cm i.d.), sealed
and counted over 24 h. 137Cs and 210Pb were determined using the 661.6 and 46.5 keV photopeaks, respectively. The samples were counted again at least 30 days after sealing and the 226Ra content was estimated from the 214Bi (609.3 keV) and 214Pb (352.0 keV) photopeaks (Gilmore and Hemingway, 1995). The excess 210Pb were determined as the difference between total 210Pb and 226Ra activities (Radakovitch et al., 1999). Also, 137Cs were measured by its emission at 662 keV. The absolute efficiencies of the detectors were determined using calibrated sources and sediment samples of known activity. The mass accumulation rate (MAR) of any metals was calculated as follows; some element concentration (lg/g) dry bulk density (cm2) linear sedimentation rate (cm/ year). As each coring places are thought to have different oceanographic conditions such as productivity changes through the seasonal variation, different current and circulation systems, sedimentary environment of the each place might be expected different. Also, because of the accumulation rate of heavy metal is strongly associated not only with the influx of metal but also benthic environment such as sedimentation rate and sediment grain size, the metal concentration of three sites may be different each other. This oceanographic difference among site may provide valuable insight into concentrations of heavy metal accumulation.
Please cite this article in press as: Cho, J., et al. Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea. Mar. Pollut. Bull. (2015), http://dx.doi.org/10.1016/j.marpolbul.2015.03.034
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J. Cho et al. / Marine Pollution Bulletin xxx (2015) xxx–xxx Table 1 Summary of various data in three cores.
a b
BGa
MS-PC2 (60 cm) Range
TOC (%) CaCO3 (%) C/N Mz (phi) Cr (lg/g)
90
1.0–1.6 2.0–5.5 8.8–12.6 7.3–7.7 53.5–144.9
Ni (lg/g)
68
24.4–64.0
Cu (lg/g)
45
14.8–48.5
Zn (lg/g)
95
105.2–233.0
Pb (lg/g)
20
15.7–39.9
EFb
0.73–1.23 (1.01) 0.89–1.08 (0.99) 0.95–1.49 (1.17) 0.90–1.44 (1.15) 0.75–1.89 (1.27)
MS-PC4 (40 cm) Range 1.1–2.9 0.0–8.9 6.8–12.6 7.7–10.3 0.9–77.9 11.4–31.6 15.2–72.2 119.2–318.8 22.2–64.1
EF
MS-PC5 (60 cm) Range
EF
0.8–1.6 0.0–15.3 4.1–15.3 0.01–1.21 (0.89) 0.4–1.1 (0.91) 1.0–3.7 (2.30) 0.9–2.4 (1.58) 1.0–2.8 (1.80)
42.8–81.7 10.7–27.6 10.5–78.0 50.1–310.2 5.5–68.8
0.74–1.41 (1.05) 0.45–1.16 (0.96) 0.39–2.88 (1.48) 0.44–2.72 (1.36) 0.31–3.83 (1.66)
BG is background concentration value of earth’s crust (Turekian and Wedepohl, 1961). EF is enrichment factors and (average).
The surface sediment characteristics in Masan Bay in terms of grain size distribution were investigated in previous works (Hyun et al., 2007), and they revealed that the surface sediment is mostly composed by silt to clay size materials over the entire areas. Considering this previous results, the core sediment, in particular upper part of the core sediment reflect recent sediment that has been deposited by recent sedimentation processes without any disturbances. In current study, the mean grain sizes (Mz) of two cores were variable (Table 1). The Mz varies from about 7–10 phi suggest that very fine silt to clay size particles were predominated throughout the two core. The average content of total organic carbon (TOC) and carbonate in three core sediments were shown in Table 1. The vertical TOC levels were highly variable, ranging from 0.8% to 2.9%, generally. Higher TOC levels were observed in fine sediments, whereas lower TOC levels were observed in more coarse sediments. This grain-size dependent variation in organic carbon concentrations were coincides well with previous studies (Salomons and Forstner, 1984). However, Mz is slightly coarse in core MS-PC2, and it may be expected very fine in catchment area
(Woo et al., 2003; Hyun et al., 2007). Based on this grain-size parameter, the core sediment does not contain coarse sand material which is thought to be deposited under high hydrodynamic condition such as storm surge. Even though Mz in MS-PC2 is slightly coarser than those of MS-PC4, the TOC content is mostly similar between two cores. This unusual case is attributed either very low range of grain-size variation or specific feature of core sediment of Masan Bay. The C/N ratio of organic matter exceeded 10 in several samples in Core MS-PC5. In general, the C/N ratio of organic matter indicates the source of the organic matter. When the organic matter C/N ratio is greater than 10, it is thought to have a terrigenous source, and ratios of 5–10 are considered to derive from marine sources (Stein, 1991). The C/N ratios of organic matter in the study area suggest that terrigenous organic matter was supplied from the neighboring landmass. Based on the previous work that stable carbon isotope of the organic matter was less than 26‰ in surface sediment samples, implying that a large amount of organic matter were transported from neighboring land area (Hyun et al., 2011).
Fig. 2. Profiles of excess 210Pb and 137Cs activities with sedimentation rate. Excess 210Pb were determined by subtracting the 226Ra activities from the total 210Pb activities. The sedimentation rate was derived from the linear relationship between 210Pb activities and depth of the cores (R2 is > 0.8 in this study).
Please cite this article in press as: Cho, J., et al. Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea. Mar. Pollut. Bull. (2015), http://dx.doi.org/10.1016/j.marpolbul.2015.03.034
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J. Cho et al. / Marine Pollution Bulletin xxx (2015) xxx–xxx
Fig. 3. Historical trends in heavy metals concentration (Cu, Pb and Zn) and their mass accumulation rate (MAR). Calendar age was calculated based on the decay of excess 210 Pb. Note that the elemental MARs were drown with the same scale. Abrupt increase was clear in core MS-PC5 at around 1970s.
Therefore, higher C/N ratios recognized in core MS-PC5, could be confirmed that some part of terrestrial material could be supplied from nearby land areas. The carbonate content of the surface sediments varied from 0.0% to 15.3% (Table 1). In general, carbonate content is controlled by the input of terrigenous materials (dilution), productivity levels, and carbonate dissolution (Stein, 1991). This value of carbonate content occurred in three cores are generally lower than those of open ocean where the carbonate content reaches several tens of percentage if the water depth lies above the carbonate compensation depth (CCD). Some anoxic bottom condition was reported in previous work (Choi et al., 2005; Hyun et al., 2007), therefore probably carbonate dissolution could have occurred.
The extremely variable carbonate levels observed in this study could reflect the anoxic bottom conditions or the presence of shell fragments in the near-shore sediments. However, generally lower carbonate content in three cores could not be evaluated in present study, but it could not exclude that some part of carbonate could have subjected to dissolution due to the extremely depleted oxygen content in catchment area. The sedimentation rate was calculated on the basis of 210Pb data as shown in Fig. 2. In MS-PC2 and MS-PC5, the sedimentation rate was very similar, they are 0.44 ± 0.3 cm/yr and 0.41 ± 0.11 cm/yr, respectively. These sedimentation rates were slighter higher than previous work (0.33 cm/yr) of Woo et al. (2003). In MS-PC4, however the sedimentation rate is 0.28 ± 0.1 cm/yr, showing similar
Please cite this article in press as: Cho, J., et al. Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea. Mar. Pollut. Bull. (2015), http://dx.doi.org/10.1016/j.marpolbul.2015.03.034
J. Cho et al. / Marine Pollution Bulletin xxx (2015) xxx–xxx
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Fig. 4. Principal Component Analysis (PCA) of loading plots of various components in three cores. Most metals in core MS-PC5 were concentrated together, whereas distribution patterns in MS-PC2 and MS-PC4 do not show the similar pattern.
with the report in Masan Bay (Woo et al., 2003). Entirely, sedimentation rate of the current study do not show any higher deviation, implying reasonable measurement. As shown in Fig. 2, liner regression lines of the three 210Pb data point shows high correlation coefficient. The ranges of heavy metals concentration (Cr, Ni, Cu, Zn and Pb) in three cores were illustrated in Table 1. Generally, elemental concentration seems to higher toward to core top, recent year with a boundary of 1970s, in which higher concentration and approximately correspond to the timing of the initiation of vigorous anthropogenic activity. Also, the enrichment factor (values) of heavy metal concentration shows spatial variation; higher enrichment values in catchment core and vise versa (Table. 1). In case of MS-PC5, the enrichment factor is as much as 1.5–2 times higher than those of MS-PC2, which is located in offshore area, and not being influenced from anthropogenic contribution. In earlier studies, Feng et al. (2004) and Zhang and Liu (2002) used the enrichment factor (EF) as an indicator of the degree of pollution or of environmental contamination as follows. Enrichment factor (EF) = {(X/Al)sample/(X/Al)mean sediment}. In this formula, (X/Al)sample is the metal to Al in the samples of interest, and (X/Al)mean sediment is the natural background value of the metal to Al ratio (Rubio et al., 2000). Values of EF between 0.5 and 1.5 were interpreted as indicating that the element may be associated with crustal material or natural weathering processes. Values of EF greater than 1.5 suggested that a significant portion of the metal was associated with non-crustal material and/or weathering processes, i.e., the metal was supplied by other sources. As suggested by Zhang and Liu (2002), the presence of EF values greater than 1.5 at a large number of sampling stations indicates metal accumulation from anthropogenic sources.
The content and EF values of Cr, Ni, Cu, Zn and Pb and their MAR’ are illustrated in Fig. 3 and Table 1. Most EF values for five metals were ranged from 0.01 to 3.83. The EF values of samples with values < 1 were considered not to have accumulated the element, and samples with values > 1 were considered to have accumulated the element. In other words, elemental accumulation varied greatly, indicating that accumulation resulted from a combination of natural and anthropogenic sources. Thus accumulation above the natural value would be attributed to pollutant effects. In three cores, metal concentration showed increasing tendency since the 1970s. In particular, MARs of Cu, Pb and Zn in MS-PC5 shows synchronized pattern; abrupt increase since the 1970s and decline around 2006 yr (Fig. 3), indicating significant accumulation. Therefore, all areas were not polluted significantly in terms of heavy metal accumulation during before the 1970s, whereas this starts to increase since the 1970s. The upper parts of sediments in core MS-PC5 were polluted significantly, indicating severe pollution since the late 1970s. As a multivariate statistical technique, Principal Component Analysis (PCA) has been extensively used to identify patterns of environmental contamination (e.g., Szefer and Kaliszan, 1993; Rubio et al., 2000; Shin and Lam, 2001). Especially, Vogt (1990) interpreted sediment chemical composition and pollution sources based on a regression model derived from PCA results. Therefore, we applied PCA to interpret the variation in metal concentrations with sampling location in this study. In the case of the surface sediment in Masan Bay, metal concentrations could be divided into four groups: aluminosilicate-bound elements, carbonatebound elements, redox-sensitive elements, and anthropogenic elements (Hyun et al., 2007). In particular, some heavy metal such as Co, Cr, Ni and Ni are strongly associated each other
Please cite this article in press as: Cho, J., et al. Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea. Mar. Pollut. Bull. (2015), http://dx.doi.org/10.1016/j.marpolbul.2015.03.034
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J. Cho et al. / Marine Pollution Bulletin xxx (2015) xxx–xxx
and thus interpreted as end member of terrigenous and anthropogenic elements. In this present study, loading plots for the three cores are quite different from the surface sediment of previous work of Hyun et al. (2007). It seems that most elemental distribution in two cores (MSPC2 and MS-PC4) are scattered through all areas with one cluster of ON, OC indicating that most of these element is not constrained by one factor only. Instead, they were associated with various factors. Considering that elemental concentration is mainly associated with previous mentioned four factors, these wide ranged scattering imply that the characteristics of each elements are associated with one or two factors of four (Fig. 4). The organic components of OC and ON in these two core sediment, however seems to shows outlier, potentially deviated from whole component, implying different PCA component. In case of MS-PC5, however all components seems to be divided into three group. The first one is carbonate matrix, the second is organic carbon and nitrogen, and the last group is remaining heavy metal group, which can be attributed to anthropogenic sources and terrestrial sources potentially (Fig. 4). In Masan Bay core sediments, metal concentration is characterized by the spatiotemporal variation. Entirely, metal concentration seems to be increasing toward the catchment area of Masan Bay. In offshore area, EF and MAR do not show larger fluctuation, both EF and MAR are less than 2, and the MARs of Pb and Zn are less than 20 and 80 lg/cm2yr, respectively. These values were quite lower than those of MS-PC4 and MS-PC5. Temporally, EF and MARs of Cu, Pb and Zn start to increase from around the 1940s and this timing is also coincident with the timing of the initiation of industrial activities in Masan Bay. However, mostly high accumulation rate seems to be started in 1970s in central and catchment core sites. Most increased EF and MARs, however, were recognized in catchment site, showing over than 3 in EF and over than 140 lg/cm2yr in case of Zn. This increased value is much higher than that of offshore values. Slight decrease of EF and MAR of Zn and Pb were recognized in catchment site since the 2004s, but it is hard to evaluate the cause of this decreasing tendency. Concentrated efforts to lessen the metal effluences from government could be one reason to be considered. However, for more accurate evaluation, continuous geochemical research is necessary. Acknowledgements The authors thank to anonymous reviewers for their critical reading of original document. This study was conducted by the support from the grant of KIOST’s project entitled ‘‘Environmental Changes in the Seomjin River Estuary’’ (PE99334). KIODP project (PM58300) funded by ‘‘Ministry of Ocean and Fisheries’’ supported this research in part.
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