Laboratory and field magnetic evaluation of the heavy metal contamination on Shilaoren Beach, China

MPB-08380; No of Pages 11 Marine Pollution Bulletin xxx (2017) xxx–xxx

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Laboratory and field magnetic evaluation of the heavy metal contamination on Shilaoren Beach, China Yonghong Wang a,⁎, Qinghui Huang b, Charles Lemckert c, Ying Ma a a b c

Key Lab of Submarine Geosciences and Prospecting Techniques, MOE, College of Marine Geosciences, Ocean University of China, Qingdao 266100, PR China Key Laboratory of Yangtze River Water Environment of the Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China Griffith School of Engineering, Gold Coast Campus, Griffith University, 4222 Queensland, Australia

a r t i c l e

i n f o

Article history: Received 27 July 2016 Received in revised form 26 January 2017 Accepted 28 January 2017 Available online xxxx Keywords: Magnetic properties Lab and field measurements Heavy metals Shilaoren Beach, China

a b s t r a c t This study uses magnetic measurements to evaluate the heavy metal contamination of the surface sediments on Shilaoren Beach. The values of the laboratory magnetic measurements have a positive relationship with the concentrations of Fe, Mn, Cr, Ni, As and Pb. The field magnetic parameter provides an effective and rapid method for evaluating the distribution and dispersal of heavy metal. Sediments with higher heavy metal contents generally accumulate near higher and lower tide lines on the beach, reflecting the control of waves and tides. The sewage and stormwater outlets are the primary sources of the heavy metal contamination. Variations in seasonal waves and winds affect the sediment transport and the heavy metal distribution patterns. Based on the Australian ISQGLow sediment quality criteria, Fe, Mn and Cr generally exhibit intermediate accumulation levels, whereas Pb and Zn exhibit higher accumulation levels because of the socioeconomic status of the area surrounding the beach. © 2017 Elsevier Ltd. All rights reserved.

1. Introduction Sediments are frequently described as sinks for heavy metals because the heavy metal concentrations within sediments frequently exceed the concentrations in seawater by several orders of magnitude (Izquierdo, 1997; Ramirez et al., 2005). Estimates indicate that b 1% of heavy metals remain dissolved in water and that N 99% is stored within sediments (Bartoli et al., 2012). Although heavy metals are naturally occurring substances, they can enter the environment through anthropogenic processes (Song et al., 2014), including through sewage and stormwater outlets, increased mining and beach nourishment activities related to rapid urbanization, intensive economic development and population growth. Heavy metals, such as Cr, Hg, Pb, Cu and Zn, at excessive concentrations in sediments are regarded as serious pollutants in aquatic ecosystems because they can affect marine biota and threaten human health through ingestion via the food chain or external contact, with the metals acting as a source of skin allergens (Kishe and Machiwa, 2003; Mucha et al., 2003; Feng et al., 2004; Zhang et al., 2007). Heavy metals can accumulate in different marine sedimentary environments that have fine sediments, such as tidal flats (Zhang et al., 2009; Feng et al., 2004, 2011), salt marshes (Izquierdo, 1997), lakes (Kishe and Machiwa, 2003), estuaries and deltas (Mucha et al., 2003; Dong et al., 2014) and bays (Zhang et al., 2007; Song et al., 2014). However, sandy sediments have been generally neglected because of their large particle ⁎ Corresponding author. E-mail address: [email protected] (Y. Wang).

size, which minimizes large accumulations of metals (Lacerda et al., 1985). Heavy metal contamination on beaches has been a growing concern since the 1990s because beaches have experienced increased recreational activities and heavy metals pose a long-term public health risk (Ramirez et al., 2005; Gurhan, 2009; Vidinha et al., 2009; Mansour et al., 2013; Foteinis et al., 2013; Jayasiri et al., 2014). The Government of Western Australia implemented the Beach Health Program from 2004 to 2006 (Department of Water, Government of Western Australia, 2007). This program evaluated the heavy metal concentrations on beaches in Perth and found that certain levels exceeded the recreational or health guidelines for Cu and Pb. Other similar assessments were conducted in Italy (Caredda et al., 1999; Covelli et al., 2001), India (Nobi et al., 2010; Suresh et al., 2015; Jayasiri et al., 2014), Mexico (Carranza-Edwards et al., 2001), Chile (Ramirez et al., 2005), Portugal (Vidinha et al., 2006), Egypt (El-Kammar et al., 2007; Mansour et al., 2013; Foteinis et al., 2013), Turkey (Coban et al., 2009) and Oman (Al-Shuely et al., 2009). These studies found that different types of heavy metal contamination occur on beaches, indicating that heavy metal contamination on beaches is not a rare phenomenon. Therefore, understanding and assessing heavy metal pollution is becoming vitally important to public safety. Generally, heavy metal concentrations are determined through chemical analyses or bio-indexing (Haynes and Toohey, 1998; Fiori and Cazzaniga, 1999); however, these methods are slow and time consuming. Recently, sediment magnetic properties have been analyzed in the laboratory using magnetic measurements, and this technique has the potential to provide a rapid, sensitive and low-cost approach for

http://dx.doi.org/10.1016/j.marpolbul.2017.01.080 0025-326X/© 2017 Elsevier Ltd. All rights reserved.

Please cite this article as: Wang, Y., et al., Laboratory and field magnetic evaluation of the heavy metal contamination on Shilaoren Beach, China, Marine Pollution Bulletin (2017), http://dx.doi.org/10.1016/j.marpolbul.2017.01.080

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characterizing heavy metals in fine sediments from different natural environments (Wang, 2013; Dong et al., 2014). In addition, field magnetic measurements may provide a rapid method of tracing the distribution of heavy metals. However, the reliability of the results has not yet been established. This research uses Shilaoren Beach as an example to (1) extensively examine the relationship between heavy metal concentrations derived from laboratory magnetic measurements; (2) test whether field magnetic measurements can reliably trace the dispersal pattern of heavy metals in surficial beach sediments; (3) analyze the reasons for heavy metal distributions on beaches; and (4) compare the heavy metal contamination status of Shilaoren Beach with that of beaches in other countries. 2. Geographic setting This study was conducted on Shilaoren Beach on the Qingdao Coast of China (Fig. 1). The Qingdao Coast is located within the second uplift area of the Meso-Cenozoic Pacific-related tectonic system in East Asia, which has experienced gradual, but uneven uplift since the Meso-Cenozoic. The uplift has formed an irregular coast and a circuitous headland bay under the influence of marine and terrestrial geological processes

(Fig. 1A). This region is in a warm temperate zone that experiences coastal monsoons. The average air temperature is 12.4 °C, and the rainfall ranges between 400 and 1335 mm a−1, with an average value of 735 mm a−1. Higher rainfall occurs in spring and summer, which account for 57% and 22% of the annual rainfall, respectively. The rainfall in autumn and winter accounts for 14% and 7%, respectively (Compilation Committee of Chinese Bays, 1993). The perennial wind directions are predominantly SSE and NW, and the wind has an average speed of 5.5 m/s (Zheng et al., 1998). The prevailing wind direction in spring and summer is SE, and the minimum average speed of 4.7 m/s occurs in July and August. In autumn and winter, the prevailing wind direction is NW, and the minimum average speed of 6.4 m/s occurs in November. The wind directions with higher wind frequencies are SE, N and NNW (Fig. 2). The coast experiences semi-diurnal tides with a range of 1.9–3.5 m. The prevailing waves approach from the SE in spring and summer but from the NW in autumn and winter (Fig. 2). The average wave heights are 3.1 m and 1.4 m in summer and spring, respectively, and 2.1 m and 1.9 m in autumn and winter, respectively. Few rivers are located in the study area. The coast in the vicinity of Shilaoren Beach consists of granite and metamorphic rock, and the beach faces the Yellow Sea. The shoreline of Shilaoren Beach is oriented in a nearly

Fig. 1. Study area of Shilaoren Beach, Qingdao, China (A), and the field magnetic measurement transect lines 1–10 and A–E. The sediment sampling locations are indicated by the blue dots (B). The inserted panels show the stormwater sewage outlets located to the northeast (a) and southwest (b, c). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Please cite this article as: Wang, Y., et al., Laboratory and field magnetic evaluation of the heavy metal contamination on Shilaoren Beach, China, Marine Pollution Bulletin (2017), http://dx.doi.org/10.1016/j.marpolbul.2017.01.080

Y. Wang et al. / Marine Pollution Bulletin xxx (2017) xxx–xxx

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Fig. 2. Wind frequency (left), frequency with the 10% highest wave height (middle), and average wave speeds (right) along the Qingdao Coast for the period from 1980 to 1990 (Compilation Committee of Chinese Bays (division 4), 1993).

NE–SW direction and has a length of 2010 m and an average backshore width of 80 m (Wang et al., 2012). Sewage and stormwater discharge outlets are located to the NE and SW on both sides of the beach (Fig. 1B). 3. Data and methods

3.2.2. Magnetic measurements of dry and wet samples in the laboratory The low-frequency (χlf) and high-frequency (χhf) magnetic susceptibility values of eight dry and 21 wet surface samples collected during the summer were measured in the laboratory. Then, all samples were dried at 40 °C, and the χlf and χhf values were measured again.

3.1. Field work 3.1.1. Seasonal field magnetic measurements In this study, 15 profile lines were established on Shilaoren Beach to measure the volume magnetic susceptibility (κ) in field (Fig. 1B). These transects were perpendicular to the coastline and spaced every 60– 70 m along the beach, and they extended from the foreshore wet beach with a high water content (from the low tide line to the high tide line) to the backshore dry beach with a low water content (above the high tide line) (Fig. 1B). The field magnetic measurements were conducted during winter (December 2011) and summer (August 2012) using a Bartington MS2 susceptibility system with a MS2D field prober attachment. Measurements were recorded every 1 m along each transect line and three times for every point (from which a point average value was determined). In total, 7359 volume susceptibility (κ) values were obtained at 2453 locations. 3.1.2. Sample collection Twenty-nine surface sediment samples, including eight dry samples from the backshore and 21 wet samples from the foreshore, were collected along the five transects A–E (Fig. 1B) for the magnetic and heavy metal measurements. These transects were located within the typical beach topography (backshore and foreshore zones) during winter and summer. The sample locations were recorded using a hand-held GPS, and the sediment samples were stored in plastic bags. The beach profiles were recorded using a Nikon Total Station (Leica TPS 800, TC805) along the B, C and E transects during the field magnetic measurement surveys conducted during winter and summer.

3.2.3. Magnetic measurements of different grain size samples in the laboratory Room temperature magnetic measurements of the particle size fractions consisted of χlf and χhf measurements, Anhysteretic Remanent Magnetization (ARM) and stepwise acquisition and demagnetization of the Isothermal Remanent Magnetization (IRM). The samples (5 g) were packed into a 1 cm3 styrene pot, and the χlf (0.47 kHz) and χhf (4.7 kHz) values were measured using a UK Bartington ((Model MS2) dual frequency susceptibility meter. The frequency-dependent susceptibility (χfd, in %) was calculated as χfd = 100 (χlf – χhf) / χlf. The ARM results were acquired in a 0.04 mT DC field, which was superimposed on a peak AF demagnetization field of 100 mT using a Molspin pulse magnetizer (Dtech 2000) and expressed as the susceptibility of ARM (χARM), which was measured in the same samples using a Molspin Minispin fluxgate magnetometer. Both the forwardfield (1.5 T) and back-field (− 20, − 100 and − 300 mT) IRMs were induced. The saturation isothermal remanent magnetization (SIRM) for each sample was induced in a 1.5 T steady field. Reverse fields were then applied to evaluate the S− 300 ratio parameters, including S−100 = 100 (SIRM − IRM−100 mT) / SIRM and S−300 = 100 (SIRM −

3.2. Laboratory work 3.2.1. Particle size analysis and separation in the laboratory The beach sediment samples were dried, weighed, and sieved at 1/4 Ф ranges using an electric mechanical sieve shaker. The particles were dried at 40 °C and then passed through the sieves, which consisted of six particle size fractions (0.063–0.125, 0.125–0.25, 0.25–0.5, 0.5–1, 1– 2 and N2 mm). A total of 165 samples were evaluated, and few sediment particles were observed below 0.063 mm. The sorted sieved samples were weighed for the laboratory magnetic and heavy metal analyses. Sediments in the particle size fractions of 0.063–0.125, 0.125–0.25, 0.25–0.5, and 0.5–1 mm were observed under an OLYMPUS SZX16 stereomicroscope to identify the concentrations of magnetic minerals in the different particle size fractions.

Fig. 3. Mean particle size (Mz) of the sediments on Shilaoren Beach in different seasons. The black circles represent the Mz near the high tide line, and the solid black dots represent the Mz in the backshore and foreshore. The results indicate that sediments in December are generally coarser than the sediments in August and that the sediments near the high tide line are much coarser than the sediments in the backshore and foreshore.

Please cite this article as: Wang, Y., et al., Laboratory and field magnetic evaluation of the heavy metal contamination on Shilaoren Beach, China, Marine Pollution Bulletin (2017), http://dx.doi.org/10.1016/j.marpolbul.2017.01.080

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Y. Wang et al. / Marine Pollution Bulletin xxx (2017) xxx–xxx

IRM−300 mT) / SIRM (Thompson and Oldfield, 1986; Dunlop and Őzdemir, 1997).

have different nitration results during the nitrolysis processes. However, recoveries N 70% are considered reasonable and acceptable.

3.2.4. Heavy metal analysis The heavy metal concentration analyses were performed using standard techniques. The 58 beach surface sediment samples collected from transects A–E during winter and summer were dried at 60 °C and powdered using an agate mortar and pestle. The concentrations of heavy metals were then determined in duplicate using inductively coupled plasma mass spectrometry (ICP-MS). A nationally certified reference material (GSD-3a) from China was applied to ensure the accuracy and precision of the total content analysis of heavy metals within the sediment. The recoveries of different heavy metals varied from 74% to 104% and the coefficients of variation were b15% in six replications. The recovery was 74% for Zn, between 82% and 84% for Cr, Ni, Cu and Pb, and N 98% for As, Cd and Sb. This variation is because different metals

4. Results

Table 1 Heavy metal content for Shilaoren Beach. Units for metals are expressed in mg kg−1, and Fe is in %. All of the background values for metals are crustal averages (Taylor and McLennan, 1985). Highlighted numbers indicate values above the Australian ISQG-Low standard. A0 1 A0 2 A0 3 A0 4 A05 A06 B01 B0 2 B0 3 B04 B05 B06 C01 C02 C03 C04 C05 C06 D01 D02 D04 D05 D06 E01 E02 E03 E04 E05 Summer ave A0 1 A0 2 A0 3 A0 4 A05 A06 B01 B0 2 B0 3 B04 B05 B06 C01 C02 C03 C04 C05 C06 D01 D02 D04 D05 D06 E01 E02 E03 E04 E05 Winter ave I* I I* I I I* Australian ISQG-Low Florida SQG Background

Cr 131.3 60.8 16.1 86.8 22.0 37.4 34.6 30.5 17.7 16.0 48.0 48.5 109.4 196.1 22.8 19.2 54.1 78.0 225.7 41.0 81.4 47.2 31.1 55.6 213.7 70.5 31.1 78.2 68.7 115.7 173.9 183.7 68.2 171.6 64.4 50.7 51.9 112.8 76.7 180.6 88.4 134.5 185.9 86.0 58.8 113.8 63.0 165.0 60.3 69.8 59.0 105.6 132.8 286.6 203.7 84.2 61.0 116.5 80 150 270

Ni 18.0 16.0 11.3 15.0 21.2 11.6 11.9 10.0 9.7 10.4 14.7 35.1 17.2 22.4 6.9 8.4 10.4 12.0 22.4 12.8 11.0 13.3 10.0 15.5 22.1 13.2 8.0 13.1 14.7 26.7 37.9 48.2 23.6 26.0 18.0 24.1 16.8 37.7 16.0 19.0 17.0 22.2 23.5 19.0 9.0 24.0 8.0 9.0 9.0 14.0 8.0 23.0 25.0 28.0 26.0 19.0 18.0 21.3

Cu 20.0 16.0 12.0 15.0 13.0 17.1 19.8 9.0 13.1 18.4 21.5 18.0 15.1 22.3 8.1 10.4 10.7 10.8 20.6 10.5 11.0 14.5 10.5 18.0 16.6 15.5 9.1 14.2 15.0 24.6 24.4 22.3 23.4 25.0 9.0 23.8 17.8 27.0 11.0 27.0 14.0 17.1 23.1 13.0 8.0 15.0 11.0 10.0 13.0 12.0 15.0 8.0 18.0 15.5 25.0 15.0 10.0 17.1 35 100 200

Zn 68.0 38.0 18.4 48.0 26.4 26.4 31.0 27.0 19.9 19.3 29.0 47.0 64.6 88.8 22.9 24.8 34.6 39.1 95.4 30.8 46.0 33.2 26.8 34.1 80.0 46.2 25.8 40.7 40.9 62.4 93.1 87.5 57.7 85.0 45.0 37.2 44.8 64.5 50.0 90.0 54.0 65.7 93.2 53.8 43.6 64.3 45.2 46.0 44.2 47.7 43.7 61.2 71.4 128.0 98.0 53.2 44.4 63.8 150 350 600

As 17.0 14.0 10.5 19.0 11.1 12.3 13.8 13.0 11.3 10.1 10.6 12.1 15.5 18.7 10.3 12.9 13.7 13.0 19.7 14.9 15.0 15.1 14.1 14.3 24.5 16.0 13.5 15.4 14.5 16.0 18.6 18.8 15.7 23.0 14.0 15.8 15.4 17.3 14.0 20.0 19.0 17.7 19.7 12.0 16.0 17.0 10.0 11.0 14.0 10.0 16.0 18.0 20.0 24.6 22.0 15.0 10.0 16.6 20 65 93

Cd 0.18 0.10 0.07 0.13 0.03 0.05 0.06 0.06 0.03 0.02 0.05 0.06 0.16 0.22 0.04 0.04 0.07 0.09 0.27 0.10 0.12 0.09 0.06 0.09 0.36 0.13 0.06 0.11 0.13 0.19 0.21 0.18 0.13 0.21 0.12 0.09 0.11 0.16 0.13 0.22 0.14 0.16 0.20 0.14 0.12 0.16 0.12 0.12 0.12 0.13 0.12 0.16 0.18 0.30 0.24 0.14 0.12 0.16 0.5 1.5 5

Sb 0.42 0.31 0.18 0.35 0.25 0.25 0.28 0.26 0.19 0.17 0.23 0.32 0.37 0.52 0.22 0.24 0.35 0.28 0.51 0.33 0.34 0.30 0.26 0.31 0.67 0.37 0.26 0.35 0.31 0.44 0.50 0.47 0.37 0.49 0.31 0.31 0.34 0.43 0.33 0.50 0.35 0.43 0.48 0.34 0.30 0.39 0.30 0.31 0.30 0.32 0.30 0.38 0.42 0.92 0.54 0.34 0.30 0.42

Pb 43.7 32.0 16.2 36.3 19.5 27.0 31.0 26.9 17.1 15.5 25.0 27.5 41.7 57.6 26.4 22.9 34.5 32.1 53.8 38.3 35.4 33.1 29.1 33.7 71.6 40.6 28.2 36.2 33.7 45.1 54.7 48.0 38.8 49.9 36.5 30.3 35.7 44.9 38.0 51.0 39.5 44.3 49.7 39.2 35.8 42.7 36.3 36.6 36.0 37.2 35.8 41.6 45.0 65.8 53.9 39.0 36.1 42.7 60 130 250

80

21

65

43 100

23 75

32 55

200

20

1.5

2

50

120 70

9.8

1 0.2

3

36 12.5

Fe% 6.9 4.0 1.3 5.1 1.6 2.8 2.6 2.7 1.4 1.3 4.7 4.5 7.9 13.5 1.5 2.0 5.4 6.0 15.8 3.3 4.8 4.5 2.3 4.2 12.1 6.3 2.3 6.0 5.0 7.8 11.4 11.4 6.0 9.1 4.6 4.4 4.3 9.1 5.2 9.5 5.6 10.8 14.8 5.5 4.4 6.7 4.6 4.7 4.5 4.9 4.4 6.4 7.5 18.8 10.5 5.5 4.5 7.6

5.63

Mn 1340.4 858.3 497.0 1136.0 480.0 585.0 510.0 651.5 354.0 462.0 895.0 896.0 1351.0 1735.0 418.0 1088.0 874.0 1075.0 2130.0 726.0 999.5 777.0 691.0 1085.0 1679.0 580.0 917.0 1095.0 929.4 1143.0 1638.0 1698.0 1005.0 999.5 995.3 1050.0 930.0 1273.0 1068.8 1687.8 1138.4 1428.0 1911.0 1124.4 962.2 1289.9 987.2 1000.3 971.4 1027.6 963.4 1240.8 1403.1 2239.0 1825.8 1013.5 975.1 1264.8

950

* Quality standard of marine sediments in China. Highlighted numbers indicate values above the Australian ISQG-Low.

4.1. Results based on laboratory measurements 4.1.1. Sediment particle sizes The sediments on Shilaoren Beach generally consist of sand with a typical size range of 0.5 Φ to 3.0 Φ in December and 1.2 Φ to 3.0 Φ in August (Fig. 3). As shown in Fig. 3, limited changes were observed for most of the sediment sizes (2.0 Φ to 3.0 Φ) in the backshore and foreshore of the beach. The primary changes occurred near the high tide line (0.5 Φ to 2.0 Φ) (black circles), indicating that the particle size is much coarser in winter than in summer. 4.1.2. Heavy metal content of the beach sediments According to the ANZECC ISQG-Low standard (ANZECC, 1997), heavy metal contamination occurs primarily through the considerable accumulation of Cr, Ni, As and Pb, whereas Cu, Zn, Cd and Sb tend to not accumulate to such high levels. Based on the background values of metals (crustal average) (Taylor and McLennan, 1985), the Fe and Mn contents in specific areas of Shilaoren Beach are above their respective background values and are more than one- to two-fold higher than that of samples from other areas (Table 1). According to the Marine Sediment Quality of China (2002) (Table 1), the heavy metal contaminants Cr, Ni, As, Pb, Fe and Mn can be classified into class I, class II and class III, depending on the degree of contamination (Fig. 4). For example, the Cr and Fe levels in the Shilaoren Beach sediments are in classes I and II, which indicate that the heavy metal contamination is normal and slight, respectively. Certain sediments are in class III, which indicates heavy metal contamination in these samples (Fig. 4). The heavy metal measurements in the laboratory indicate that the concentrations of heavy metals (Fe, Mn, Cr, Ni, Cu, Zn, As, Cd, Sb and Pb) in the surface sediments on Shilaoren Beach change seasonally. For example, 17 samples contain Cr contents that are N80 mg kg−1 in winter, but only six samples exceed this level in summer. The number of samples with an Fe content of N5.6% in winter is approximately three times that in summer (Figs. 4 and 5). The other heavy metals, including Ni, As, Pb, Fe and Mn, present similar seasonal changes (Table 1), and more samples have heavy metal contamination in winter than in summer (Table 1 and Figs. 4 and 5). 4.1.3. Magnetic properties of sediments on the beach 4.1.3.1. Magnetic mineral concentrations. The results from the laboratory magnetic measurements of the 165 samples within the particle size fractions of 0.063–0.125, 0.125–0.25, 0.25–0.5, 0.5–1, 1–2 and N 2 mm are presented in Fig. 6. In winter, the values of χ and SIRM ranged from 1000 × 10−8 to 10,000 × 10− 8 m3 kg− 1 and 79,000– 700,000 × 10−3 Am2 kg−1, respectively, within the 0.063–0.125 mm particle size fraction. The average values are 3316 × 10− 8 m3 kg−1 and 240,000 × 10− 3 Am2 kg− 1, respectively. However, χ and SIRM ranged from 20 × 10−8 to 120 × 10−8 m3 kg− 1 and 4000 × 10−3 to 15,000 × 10−3 Am2 kg−1, respectively, within the other particle size fractions (Fig. 6). Therefore, the χ and SIRM values within the 0.063– 0.125 mm particle size fraction accounted for between 80 and 98% of the χ and SIRM value of the bulk sample. The magnetic mineral identification using a stereomicroscope confirmed this result and indicated that most of the magnetic minerals were concentrated in the 0.063– 0.125 mm particle size fraction (Fig. 7). In summer, the values of χ and SIRM ranged from 150 × 10− 8 to 8500 × 10−8 m3 kg−1 and 80,000–660,000 × 10−3 Am2 kg−1, respectively, in the 0.063–0.125 mm particle size fraction and from 20 × 10− 8 to 140 × 10−8 m3 kg− 1 and 4000 × 10− 8 to 19,000 × 10−3 Am2 kg−1, respectively, in the other particle size

Please cite this article as: Wang, Y., et al., Laboratory and field magnetic evaluation of the heavy metal contamination on Shilaoren Beach, China, Marine Pollution Bulletin (2017), http://dx.doi.org/10.1016/j.marpolbul.2017.01.080

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fractions. The average values in winter are approximately twice as high as the values in summer. The χARM values in winter ranged from 700 × 10− 8 to 4000 × 10−8 m3 kg−1 with an average of 2556 × 10−8 m3 kg−1, whereas the χARM values in summer ranged from 200 × 10− 8 to 3000 × 10−8 m3 kg−1 with an average of 1208 × 10−8 m3 kg−1. The average χ and χARM values in winter were 1–2 times higher than the values in summer, indicating that higher concentrations of magnetic grains are present in winter than in summer. These results are consistent with the χ and SIRM values and the other particle size fractions.

4.1.5. Relationship between laboratory magnetic susceptibility and water content The χ values of wet samples were smaller than the values of their dry samples, and the lowest χ value of a wet sample was 74% of the value of the same sample after it had been dried. However, a close linear relationship (R2 = 0.97) exists between the χwet/χdry ratio and the water content (Fig. 8). Therefore, the χ values are influenced by the water content.

4.1.3.2. Magnetic granulometry. The frequency-dependent susceptibility (χfd) values from the majority of the different-sized samples were b2% in winter and summer, indicating that the superparamagnetic (SP) grains accounted for a minimal contribution to the susceptibility of sediments. Higher values of the χARM/χ ratios reflected a greater amount of stable single domain (SSD) grains, whereas low ratio values indicated a greater amount of multi-domain (MD) or SP grains (Banerjee et al., 1981; King et al., 1982). Fig. 6 shows that the χARM/χ ratio was b 1.5 in the 0.063–0.125 mm particle size fraction and ranged from two to eight in the other particle size fractions. For the 0.125–0.25, 0.25–0.5, 0.5–1, 1–2 and N2 mm particle size fractions, the average χARM/χ ratios were 4.2, 3.8, 2.9, 2.8 and 2.5 in winter and 6.1, 4.6, 3.7 and 2.2 in summer, respectively. This result indicated that much higher MD and PSD magnetic grains occurred in the 0.063–0.125 mm particle size fraction.

Based on the field κ values for the surficial sediments on Shilaoren Beach along the cross-shore beach direction, higher κ values are clearly located in two zones: above the high tide line and near the low tide line (Fig. 9). In the zone above the high tide line, the κ values range from 2000 to 4500 × 10−5 SI. In the zone near the low tide line, the wet sediments feature κ values from 150 to 200 × 10−5 SI (Table 3 and Fig. 10). Based on a comparison of these κ values with the laboratory analytical results for the heavy metals in the sediment samples, these two zones correlate with zones of Cr, Ni, Pb, Fe and Mn contamination based on the ANZECC ISQG-Low standard (ANZECC, 1997) and the Marine Sediment Quality of China (2002) (Table 1). Lower average κ values are observed in the southwestern sections along the beach shoreline, including profiles 1 to B. The lower average κ value is approximately 200–300 × 10−5 SI, and the highest κ value is generally b 2000 × 10−5 SI. The higher κ values are in the northeastern sections and include profiles 5–10, which have average κ values of approximately 600–800 × 10− 5 SI and a highest κ value of

4.1.3.3. Magnetic mineral types. The S−100 parameter indicates the relative proportion of ferromagnetic (e.g., magnetite) and anti-ferromagnetic (e.g., hematite and goethite) minerals, and S− 300 is a similar ratio parameter (Thompson and Oldfield, 1986). Within the particle size fraction of 0.063–0.125 mm, the S−100 values for all samples ranged between 82 and 92%, and the S−300 values were N 96% (Fig. 6), suggesting that the ferromagnetic minerals were dominated by low-coercivity minerals, such as magnetite and maghemite. In the other particle size fractions, the S−100 values ranged from 74 to 80%, and the S−300 values ranged from 93 to 98%, indicating that higher concentrations of ferrimagnetic grains were present in the b 0.125 mm particle size fraction than in the other size ranges. In winter, most of the S− 100 values for all of the particle size fractions were N88%, although these values were b88% in summer. Therefore, higher concentrations of ferrimagnetic mineral grains were present in winter than in summer. In summary, higher concentrations of ferrimagnetic and coarser magnetic grains were observed on the beach in winter than in summer. These magnetic grains were primarily present in the 0.063–0.125 mm particle size fraction of the bulk sample. 4.1.4. Relationship between heavy metals and laboratory magnetic properties This study shows a close linear relationship (R2 = 0.6–0.8) between magnetic susceptibility (χ) and heavy metal concentration (Table 2 and Fig. 4). This is consistent with previous studies showing that magnetic parameters are suitable proxies for heavy metal concentrations in different sedimentary environments, including subaqueous deltas, agricultural soils, urban street dust and city bays (Chan et al., 2001; El-Baghdadi et al., 2011; Dong et al., 2014; Li et al., 2014). In this beach environment, χ represents the concentrations and distributions of Fe, Cr and Mn (R2 = 0.8). Cr and other heavy metal contamination occur on the beach when χ exceeds 2000 × 10−8 Am2 kg−1 (Fig. 4). χ can also be used to approximate the As, Sb, Cd and Pb concentrations (R2 = 0.6). t-test showed that when the correlation coefficients are N0.5, magnetic parameters and heavy metal contents are statistically significant (For example, when R2 = 0.83, T (= 9.98) ≥ T (df) 0.01, and P b 0.0001. When R2 = 0.56, T (= 4.53) ≥ T (df) 0.01, and P b 0.0001). However, χ did not explain the changes in the Ni and Cu concentrations (R2 = 0.1–0.3) (When R2 = 0.29, T (= 2.03) ≥ T (df) 0.01, and P = 0.048).

4.2. Field magnetic properties and their relationship with heavy metals

Fig. 4. Magnetic parameter χ and Cr and Fe concentrations in different seasons (black dots: winter; black circles: summer). Heavy metal concentrations in December are generally higher than in August. Heavy metal contamination can be classified into class I, class II and class III based on the Chinese Quality Standard of Marine Sediments.

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Y. Wang et al. / Marine Pollution Bulletin xxx (2017) xxx–xxx

N4000 × 10−5 SI. Therefore, lower average heavy metal concentrations occur in the northeastern sections (Table 3 and Fig. 9). Seasonal changes of κ values are not evident based on Table 3 and Fig. 10. The κ values in the southwestern sections are slightly higher in winter than in summer, with average κ values of 287 × 10− 5 SI and 232 × 10−5 SI, respectively. However, the κ values in the northeastern sections are similar in winter and summer, with average κ values of 794 × 10−5 SI and 821 × 10−5 SI, respectively (Fig. 10). 5. Discussion 5.1. Index significance of magnetic measurements on the heavy metal distribution 5.1.1. Laboratory magnetic measurements and heavy metals The elevated concentrations of heavy metals were generally consistent with the higher χ values from the laboratory magnetic measurements. The χ, χARM and SIRM values presented close linear relationships with the concentrations of Cr, Zn, As, Cd, Sb and Pb (Table 2). For example, the χ values for Fe and Cr were b2000 × 10−8 Am2 kg−1 when the Cr and Fe concentrations were b80 mg kg−1 and 5.6%, respectively, indicating that Cr or Fe contamination did not occur (Fig. 4). Thus, Fe and Cr contamination belongs to class I according to the Marine Sediment Quality of China (2002). The χ values varied from 2000 to 4000 × 10− 8 m3 kg−1 when the Cr and Fe concentrations were 80–150 mg kg− 1 and 9.7%, respectively, which are classified as class II (Fig. 4). Similarly, the χ values varied from 4000 to 8000 × 10−8 m3 kg−1 when the Cr and Fe concentrations were 150– 270 mg kg−1 and 16%, respectively, which are classified as class III and indicated that there were Cr or Fe contamination. In fact, χ was the most prominent parameter for indicating potential heavy metal

pollution. Only a weak correlation was observed between S−100 and χfd; therefore, the S−100 value was not a suitable parameter for indicating heavy metal contamination (Table 2). 5.1.2. Field magnetic measurements and heavy metals Although the χ values obtained from the laboratory magnetic measurements provide definitive indications of heavy metal contamination in the sediment, the sample data are limited to selected areas. Field κ measurements of surficial sediments provide a rapid and high-resolution method for determining the entire spatial distribution of the magnetic concentrations on the beach. For example, a total of N 7000 κ values measured for the Shilaoren Beach sediments provided the distribution of magnetic minerals, which was then used to rapidly determine the heavy metal concentrations. In fact, similar studies have been conducted for soil samples. Pb contamination was observed in the soil of the Tadla Plain of Morocco, which had Pb concentrations of approximately 127.2 mg kg−1 and a κ value that exceeded 120 × 10−5 SI (El-Baghdadi et al., 2011), and in the topsoil of the urban Beni Mellal region of Morocco, which had Pb concentrations of 559 mg kg−1 and a κ of 577 × 10−5 SI (El-Baghdadi et al., 2011). In the dry sediments of Shilaoren Beach, the κ value ranged from 200 × 10−5 to 5000 × 10−5 SI, and the Pb concentrations ranged from 16 to 71 mg kg−1. The concentrations of Cr were between 80 and 150 mg kg− 1 when the κ values in the dry sediment were 600– 1000 × 10−5 SI, and were more N 150 mg kg− 1 when the κ values were N3000 × 10−5 SI (Fig. 9). Therefore, based on this study, heavy metal contamination may occur when κ N 600 × 10−5 SI on Shilaoren Beach. However, κ values can be influenced by multiple factors, including the background sediments, sediment water content and sediment particle size. Because the sediment particle sizes on Shilaoren Beach exhibit

Fig. 5. Distribution of Cr concentrations (mg kg−1) in sediment in different seasons based on the laboratory sample analysis. Cr concentrations in winter are generally higher than in summer. Areas that have Cr contamination in winter have concentrations which are approximately 3 times higher than in summer.

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Y. Wang et al. / Marine Pollution Bulletin xxx (2017) xxx–xxx

7

Fig. 6. Laboratory-derived magnetic results for winter and summer. The magnetic properties for the size fraction 0.063–0.125 mm (black dots: winter; black circles: summer) are different from the other five size fractions (colored dots: winter; colored circles: summer).

only limited seasonal changes in the backshore and foreshore, particle size does not play an important role in this study. Laboratory magnetic measurements of wet and dry samples from the same site showed that a close relationship exists between the magnetic susceptibility and water content (Fig. 8). Since the κ value of 10 ml of water is −0.9 × 10−5 SI, which decrease the κ values of wet sediments. In wet sediment, the heavy metal measurements indicated that the sediments exhibited heavy metal contamination when the κ value was N150 × 10−5 SI. For example, on Shilaoren Beach, the κ values of wet samples were N150 × 10− 5 SI when the Cr concentrations ranged from 80 to 150 mg kg−1 (Fig. 10). Although the measured κ values exhibited different ranges in different areas, heavy metal contamination must be considered within a given study area when the κ values of certain samples are approximately 5 times higher than the κ values of other samples,

when the waves retreat from the beach to the sea, thereby moving coarser but sparser sediment toward the sea and leaving the finer but denser sediment slightly above the high tide line zone. Heavy metals associated with the finer sediment particles on beaches will typically remain in these areas, and similar distributions have been observed on Cedar Beach, Canada, which presented higher κ values near the upper swash zone (near the high tide line) (Zhang et al., 2010). Additionally, waves breaking at an angle onto a beach will result in a swash that is directed diagonally up across the beach profile, which causes littoral transport and results in the transportation of sediment in an alongshore direction. The South Shandong Coastal Current passes Shilaoren Beach from the NE to the SW in summer and winter. Because the prevailing wind and waves in spring and summer are from the SE direction, the net sediment transport in summer is alongshore from the NE to the SW (Fig. 10). In winter, the prevailing winds and waves approach from the NW direction and cause sediment transport from the

5.2. Factors that influence the heavy metal distribution throughout the surface sediments of beaches Generally, the primary mineral inputs of a beach dictate the background of heavy metal contents. Hydrodynamic sorting on beaches plays an important role in heavy metal distribution. Field surveys indicate that no rivers are located near the beach and that beach nourishment does not occur. The nearby cliffs of granite and metamorphic rocks are the main sources of beach sediment and control the natural background values of the heavy metals. However, other inputs, including sewage outlets, can change the distribution of heavy metals on a beach. 5.2.1. Hydrodynamics and sediment transport A spatial zoned distribution was observed for the magnetic grains and heavy metals on Shilaoren Beach, with higher concentrations of heavy metals and magnetic grains occurring primarily above the high and low tide lines (Fig. 10). Some beach sediments have been found to have higher magnetic susceptibility due to hydrodynamics (Hatfield et al., 2010). The observed zonation was caused by the much stronger forward swash relative to the weaker backwash that occurs after a wave breaks. Thus, weak hydrodynamic areas form near these zones

Fig. 7. Images showing the different concentrations of magnetic grains (indicated by white arrows) in the different sediment particle size fractions under a stereomicroscope.

Please cite this article as: Wang, Y., et al., Laboratory and field magnetic evaluation of the heavy metal contamination on Shilaoren Beach, China, Marine Pollution Bulletin (2017), http://dx.doi.org/10.1016/j.marpolbul.2017.01.080

Y. Wang et al. / Marine Pollution Bulletin xxx (2017) xxx–xxx

Zn

Mn

Ni

Cu

As

Sb

Cd

Pb

0.83 0.82 0.83 0.07 0.02

0.83 0.83 0.85 0.11 0.02

0.83 0.82 0.83 0.13 0.05

0.77 0.75 0.77 0.11 0.06

0.29 0.27 0.29 0.12 0.08

0.17 0.14 0.16 0.05 0.08

0.56 0.58 0.59 0.11 0.02

0.58 0.63 0.62 0.07 0.03

0.66 0.66 0.68 0.15 0.09

0.62 0.63 0.65 0.07 0.04

SW to the NE, but the South Shandong Coastal Current still flows from the NE to the SW. Thus, bidirectional transport occurs in the backshore of the beach in winter (Fig. 10), and heavy metals from the west outlets are transported from profile 1 to profile 7, leading to greater heavy metal contents in winter. Moreover, a NW wind in winter transports fine and light minerals to the sea and leaves the heavy minerals on the beach. The seasonal variations in the hydrodynamics and winds likely play important roles in the spatial distribution of sediment and beach dynamics (Trenhaile et al., 2000). The minimum average prevailing wind speed is 4.7 m/s in July and August and 6.4 m/s in November. Thus, the stronger winds in winter likely transport fine sediment and leave coarser and denser sediment on the beach. Therefore, the beach generally has more heavy metals in winter than in summer. In addition, the heavy metal content of Mumbai Beach in India was also reported to be high in November (Jayasiri et al., 2014). 5.2.2. Source of the heavy metals The source of the heavy metals in the sediment affects the distribution of these contaminants. Besides natural source, other possible sources of heavy metals in the beach are the sewage and stormwater outlets that drain into the beach area (Fig. 1). These inputs result in higher heavy metal contents and higher magnetic parameters around the outlets areas. Analysis of a Pearson's bivariate correlation matrix showed the extent of the relationship between the investigated elements (Table 4). The Fe contents were positively and closely correlated with the contents of other heavy metals, including Cr, Zn, and Mn (R2 N 0.9) and As, Sb, Cd, and Pb (R2 = 0.78–0.84) but not Cu and Ni (R2 = 0.2–0.4). The metals with strong positive correlations were likely from the same source, whereas those with strong negative correlations likely were from different sources (Gurhan, 2009). Table 1 also shows that certain samples had heavy metal concentrations that were higher than the respective background values (crustal average). The CF values (contamination factor = measured concentration of heavy metal/

(10 -5 SI)

Cr

Water contents ( )

35 30

150 200 Distance / m

250

300

6

4 2

1200

Backshore

0

800

-2

Foreshore

-4 -6

0 0

50

100

150 200 Distance / m

250

300

Fig. 9. Changes in κ values along profile B (the black line shows the change in κ values, and the red line shows the topography of profile B) in the different seasons. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

background concentration) for the identified metals (except Cu and Ni) were greater than one because of the influence of external sources. Therefore, the heavy metals on Shilaoren Beach, including Fe, Cr, Zn, Mn, As, Sb, Cd, and Pb, were closely correlated and had the same natural and non-natural sources. However, the CF of Cu and Ni were less than Table 3 Average field magnetic susceptibility (κ in 10−5 SI) values for Shilaoren Beach. Profiles

1 2

4

15

10 5

8

0

D

C

Fig. 8. Relationship between laboratory magnetic susceptibility and the water content of the samples.

100

400

6

χ wet / χdry

-6 50

1600

20

1.0

-5

B -Winter

5

0.9

-3

2000

25

0.8

-1

-4

0

B

0.7

Foreshore

800

0

A

y = -129.27x + 128.31 R² = 0.9693

0 -2

1200

400

3

40

B -Summer

1600

(10 -5 SI)

χ χARM SIRM S−100 χfd

Fe

Backshore

Relative elevation (m)

2000

Table 2 Relationships between the magnetic parameters and heavy metal concentrations (n = 47).

Relative elevation (m)

8

9 E 10

Winter

Average Min-Max Average Min-Max Average Min-Max Average Min-Max Average Min-Max Average Min-Max Average Min-Max Average Min-Max Average Min-Max Average Min-Max Average Min-Max Average Min-Max Average Min-Max Average Min-Max Average Min-Max

Summer

Backshore

Foreshore

Backshore

Foreshore

265 ± 175 88–921 363 ± 232 95–2090 283 ± 207 73–1550 293 ± 184 36–938 271 ± 143 36–779 247 ± 132 47–878 535 ± 320 132–1636 564 ± 594 39–2933 677 ± 668 27–2991 982 ± 502 311–3280 1350 ± 886 411–3413 1283 ± 1157 162–4356 500 ± 377 137–1746 744 ± 668 109–2518 512 ± 260 64–391

75 ± 38 16–158 38 ± 21 10–125 38 ± 21 14–110 42 ± 22 12–139 33 ± 10 20–59 63 ± 42 11–237 57 ± 34 18–966 69 ± 36 14–158 80 ± 68 14–244 50 ± 28 9–103 46 ± 28 16–155 74 ± 59 21–259 51 ± 41 16–83 59 ± 31 18–145 188 ± 92 53–487

187 ± 212 81–775 243 ± 164 51–582 269 ± 290 16–876 185 ± 228 20–910 172 ± 154 40–1129 338 ± 361 30–1663 572 ± 552 78–2182 574 ± 570 111–2785 951 ± 1058 69–4783 742 ± 478 53–2296 1346 ± 740 127–2445 876 ± 361 220–1433 766 ± 704 109–2448 1449 ± 1181 82–3869 414 ± 289 110–554

73 ± 60 19–181 33 ± 12 17–99 33 ± 20 13–100 32 ± 10 21–61 56 ± 34 20–176 41 ± 27 16–98 42 ± 30 19–161 42 ± 25 15–168 50 ± 28 16–139 37 ± 21 14–116 99 ± 89 16–442 91 ± 100 12–326 133 ± 184 12–789 163 ± 646 23–776 127 ± 140 49–474

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Y. Wang et al. / Marine Pollution Bulletin xxx (2017) xxx–xxx

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Fig. 10. Distribution of Cr concentrations (mg kg−1) in sediments in different seasons based on field magnetic measurements (winter (A) and summer (B)). Colored dots show the sediment sampling locations and their Cr concentrations. Contours show the distribution of κ values on the beach.

one, indicating that these elements were only sourced from the natural environment. Heavy metal contamination caused by sewage and stormwater runoff has also been found in other regions. For example, high Fe and Pb contents were found in sediments on beaches near 65 stormwater drains in the Swan region of Australia (Department of Water, Government of Western Australia, 2007), and the catchments for these drains consisted mostly of coastal roads, public car parks and reserves. 5.3. Current status of heavy metals at Shilaoren Beach This study found that the sediments on Chinese and Indian beaches had higher concentrations of Pb compared with the beaches in other countries (Fig. 11). Therefore, the rapid increase in the number of vehicles in cities has resulted in an increase in the release of Pb to the sea through stormwater and sewage outlets. The metal concentrations measured in this study were compared with those from other beaches and coastal environments in different countries, as summarized by Jayasiri et al. (2014) (Fig. 11). The results of this comparison showed that the concentrations of the studied metals, such as Cd, were lower on Shilaoren Beach compared with beaches in Turkey and India. The Cr concentrations were lower on Shilaoren Beach compared with Indian and Malaysian beaches but higher compared with other beaches. The Cu and Ni concentrations of Shilaoren Beach were lower than those of certain beaches in India, Malaysia and Egypt but higher than those of two beaches in Australia, one

beach in Mexico and certain beaches in India and Malaysia. Although the concentrations of the heavy metals Cr, Cu and Ni were generally lower on Shilaoren Beach compared with certain beaches (see Fig. 11), the Pb concentrations of Shilaoren Beach were higher than those of beaches in Malaysia, Egypt, and Portugal and were close to the concentrations of the beaches in India. The Zn concentrations were generally close to those reported for beaches in India and Egypt but higher than the concentrations reported for beaches in other countries. Therefore, the heavy metal contents of Cr, Cu and Ni on Shilaoren Beach were generally considered to represent an intermediate level of accumulation, although the Pb and Zn contents were higher, which is likely due to variations in the sources of heavy metals for different beaches in

Table 4 Pearson correlation matrix for heavy metals (n = 47).

Fe Cr Zn Mn Ni Cu As Sb Cd Pb

Fe

Cr

Zn

Mn

Ni

Cu

As

Sb

Cd

Pb

1 0.97 0.93 0.90 0.37 0.20 0.78 0.78 0.84 0.82

1 0.96 0.89 0.38 0.17 0.81 0.78 0.89 0.86

1 0.86 0.47 0.27 0.84 0.76 0.90 0.88

1 0.37 0.18 0.74 0.65 0.76 0.74

1 0.55 0.31 0.27 0.31 0.31

1 0.17 0.08 0.17 0.16

1 0.74 0.87 0.91

1 0.76 0.76

1 0.93

1

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Y. Wang et al. / Marine Pollution Bulletin xxx (2017) xxx–xxx

Canadian… Florida SQG 47 ANZECC ISQG-… Perth

Australia

Ninety mile Tourist

Mexico Turkey

Beach Names

Susanoglu Kizkalesi

Egypt Portugal

Espinho Gulf of Suex Hawaii Tanjong Lobang

Malaysia

Esplanade Park Everly Lutong Mumbai Mumbai

India

Kerala Chennai Shilaoren December

China

Shilaoren August 0 5 10 15 20 0

Cd

50

100 0

Cr

40

80 0

Cu

50

100 0

Ni

60 120 0

Pb

200 400

Zn

Fig. 11. Heavy metal concentrations in the study area compared with those of other beaches from around the world. Data on the heavy metals, except for China, were obtained from the summary by Jayasiri et al., 2014. Units for metals are expressed in mg kg−1, except Fe, which is expressed in %.

different countries. The concentrations of Pb and Zn in this study and those of the Indian beaches are high because of the number of vehicles in the adjacent cities and the discharge of Pb and Zn from sewage and stormwater outlets to the seawater and then onto the beaches. Fig. 11 also shows that the average values of the heavy metal contents are mostly lower than the ANZECC ISQG-Low and Florida SQGs. 6. Conclusions (1) Laboratory experiments showed that the magnetic grain concentrations and heavy metal contents were closely correlated and that heavy metal contamination was present when the χ values were N2000 × 10−8 m3 kg− 1. Field measurements of the κ values of surficial sediments provide a rapid and high-resolution method of determining the spatial distribution of magnetic concentrations and heavy metal concentrations. Heavy metal contamination was present when the κ value exceeded 600 × 10−5 SI in dry sediment and 150 × 10−5 SI in wet sediment. Within the study area, heavy metal contamination should be considered to be present when the κ values of certain samples are approximately 5 times higher than the κ values of other samples. (2) Seasonal changes in sediment transport and hydrodynamics influence the distribution of the heavy metal contents. The source of the heavy metal contamination on Shilaoren Beach is mainly the sewage and stormwater outlets on the beach. (3) Sediments with higher magnetic grain concentrations have higher levels of Fe, Mn, Cr, Ni, As and Pb. According to the Australian ISQG-Low sediment quality criteria, the concentrations of Fe, Mn and Cr on Shilaoren Beach exceed the guidelines by a factor

of two, whereas the concentrations of Ni, As and Pb are slightly above the sediment quality criteria. A comparison of the heavy metal contents on Shilaoren Beach with those in other countries showed that the heavy metal contents of Cr, Cu and Ni on Shilaoren Beach can generally be classified as intermediate accumulation levels, whereas the Pb and Zn concentrations can be classified as higher accumulation levels because of the socioeconomic factors in the nearby region. Acknowledgements This study was funded by the National Natural Science Foundation of China (grant nos. 41376054, 41176039 and 41410304022), the National Key Research and Development Program (2016YFC0402602), and the Ocean Public Welfare Scientific Research Project, State Oceanic Administration of People's Republic of China (grant no. 201405037). The authors appreciate the Qingdao Institute of Marine Geology for providing their facilities and assistance with the laboratory work. References Al-Shuely, W., Ibrahim, Z.Z., Al-Kindi, A., Al-Saidi, S., Khan, T., Marikar, F.A., Al-Busaidi, M., 2009. Heavy metals contents on beach sediments North and South of Sohar Industrial Area, Oman. Int. J. Environ. Sci. Technol. 2 (2), 73–79. ANZECC, 1997. Australian and New Zealand Environment and Conservation Council; ISQG, Interim Sediment Quality Guidelines. Banerjee, S.K., King, J., Marvin, J., 1981. A rapid method for magnetic granulometry with applications to environmental studies. Geophys. Res. Lett. 8, 333–336. Bartoli, G., Papa, S., Sagnella, E., Fioretto, A., 2012. Heavy metal content in sediments along the Calore river: relationships with physic-chemical characteristics. J. Environ. Manag. 95, 9–14.

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Please cite this article as: Wang, Y., et al., Laboratory and field magnetic evaluation of the heavy metal contamination on Shilaoren Beach, China, Marine Pollution Bulletin (2017), http://dx.doi.org/10.1016/j.marpolbul.2017.01.080