Introduction
Brøggerhalvøya, a peninsula located on the west coast of Spitsbergen (Svalbard), has a length of approximately 20 km and is some 10 km wide. The peninsula is bordered on the north by Kongsfjorden and on the west by Forlandsendet (Miller and others Reference Miller, Sejrup, Lehman and Forman1989). The peninsula is covered by ranges of mountains and valleys with a large number of glaciers flowing into the adjacent waters.
Kongsfjorden is one of the largest glacial fjords of the Svalbard archipelago and is situated on a major tectonic boundary between the Tertiary fold-thrust belts of western Spitsbergen (Svendsen and others Reference Svendsen2002). It is oriented from southeast to northeast. The total volume of this fjord is 29.4 km3 (Ito and Kudoh Reference Ito and Kudoh1997) and it has both Atlantic and Arctic water masses. The inner fjord facing tidal glaciers has a relatively shallow water level (less than 100 m) while the outer fjord is deeper and connected with the Greenland Sea (Hop and others Reference Hop, Pearson, Hegseth, Kovacs, Wiencke, Kwasniewski, Eiane, Mehlum, Gulliksen, Wlodarska-Kowalczuk, Lydersen, Weslawski, Cochrane, Gabrielsen, Leakey, Lønne, Zajaczkowski, Falk-Petersen, Kendall, Wängberg, Bischof, Voronkov, Kovaltchouk, Wiktor, Poltermann, Prisco, Papucci and Gerland2002). It is to some extent divided into several deep basins (Cottier and others Reference Cottier, Tverberg, Inall, Svendsen, Nilsen and Griffiths2005). Kongsfjorden has recently received much research attention with focuses on seasonal hydrography (Cottier and others Reference Cottier, Tverberg, Inall, Svendsen, Nilsen and Griffiths2005), marine biology and ecosystem dynamics (Hop and others Reference Hop, Pearson, Hegseth, Kovacs, Wiencke, Kwasniewski, Eiane, Mehlum, Gulliksen, Wlodarska-Kowalczuk, Lydersen, Weslawski, Cochrane, Gabrielsen, Leakey, Lønne, Zajaczkowski, Falk-Petersen, Kendall, Wängberg, Bischof, Voronkov, Kovaltchouk, Wiktor, Poltermann, Prisco, Papucci and Gerland2002).
The distribution and concentration levels of metals varied according to the natural processes and anthropogenic activities in different areas of Arctic. The transport of metals is a consequence of atmospheric, oceanic and biological cycling of elements. Recently, the distributions of metals have been assessed from many habitats of Arctic such as sea sediments (Cai and others Reference Cai, Lin, Hong, Wang and Cai2011), seabird tissue (Blais and others Reference Blais, Kimpe, McMahon, Keatley, Mallory, Douglas and Smol2005), Cryoconites and lichens (Singh and others Reference Singh, Sharma, Gawas, Upadhyay, Naik, Pedneker and Ravindra2012) and Glacier ice cores (Singh and others Reference Singh, Sharma, Gawas-Sakhalkar, Naik, Upadhyay, Mulik, Bohare and Ravindra2013). There are reports on elevated levels of trace metals [Zinc (Zn), Copper (Cu), Lead (Pb), Cadmium (Cd), Mercury (Hg), Cobalt (Co), Nickel (Ni), Manganese (Mn) and Chromium (Cr) due to anthropogenic processes (AMAP 1998, 2005; Macdonald and others 2000; Lu and others Reference Lu, Cai, Wang, Yin and Yang2012). The distribution of trace metals in other areas of Arctic has also been assessed (Muir and others Reference Muir2003; Trefry and others Reference Trefry, Rember, Trocine and Brown2003; Braune and others Reference Braune, Outridge, Fisk, Muir, Helm, Hobbs, Hoekstra, Kuzuk, Kwan, Letcher, Lockhart, Norstrom, Stern and Stirling2005; Evenset and others Reference Evenset, Christensen, Carroll, Zaborska, Berger, Herzke and Gregor2007; Ma and others Reference Ma, Zeng, Chen, He, Yin, Zeng and Zeng2008 and Cai and others Reference Cai, Lin, Hong, Wang and Cai2011). However, there have been no systematic studies on distribution and concentrations of different metal groups (alkali metal, alkaline earth metal, transition metal and other metal groups) in the sediments of fjords on the two sides of Brøggerhalvøya and along coastal outcrops. Therefore, the aim of the present study is to determine the composition and concentration of metals in the sediments of fjords and also to compare these with elemental analysis of other Arctic regions reported in earlier studies.
Experimental
Sampling site and collection of samples
Samples were taken from fjords on both sides of Brøggerhalvøya (Fig. 1) during the Indian Arctic Expedition in 2009. A ‘grab sampler’ was used to collect accurate representative samples of the sediment from the bottom of fjords. 25 samples were collected from different depths and locations (Table 1) following strict contamination-free procedures. Each sample was collected in sterile sampling bags, transported to the laboratory and stored at -20°C until processed.
Table 1. Elemental composition (in mg/kg) of the sediments in the study area.
Fig. 1. Sampling locations on the two sides of Brøggerhalvøya peninsula, Svalbard. Map modified from the Norwegian Polar Institute's map resource. (www.toposvalbard.npolar.no)
Analytical procedure and microbiological analyses
Soil sediment samples (0.25 g) were digested in a microwave digestion system using concentrated 3 ml HNO3, 1 ml HCl, 1 ml H2O2 and 3 ml purified water. Elemental concentration in the processed samples was determined through ICPMS (Thermo Scientific ICPMS-X series II) equipped with nickel cones, a peristaltic sample delivery pump and cetac autosampler. Instrumental conditions for the ICP-MS were optimised, after completing the mass calibration and detector cross calibration, by following the manual tuning procedure using Thermo tuning Solution A containing the elements Li, Be, Co, Ni, In, Ba, Ce, Pb, Bi, and U at 10 μg/L. For data acquisition the ICPMS was operated in peak jump mode, with dwell time 20 ms, 100 sweeps, and a forward RF power of 1400 W. A CertiPUR ICP multi-element standard solution XXI for MS (Merck) was used. The elements analysed included Arsenic (As), Barium (Ba), Beryllium (Be), Bismuth (Bi), Cadmium (Cd), Cesium (Cs), Chromium (Cr), Cobalt (Co), Copper (Cu), Iron (Fe), Lead (Pb), Lithium (Li), Manganese (Mn), Nickel (Ni), Rubidium (Rb), Silver (Ag), Strontium (Sr), Thallium (Tl), Uranium (U), Vanadium (V) and Zinc (Zn). The concentrations of the elements in the sediment samples analysed in triplicate are expressed on an oven dry weight basis. 14C radiocarbon dates of two depths middle (50–60cm) and bottom layer (120–30cm) of coastal samples were dated by the accelerator mass spectrometer, at National Ocean Science Accelerator Mass Spectrometry (NOSAMS) in Woods Hole Oceanographic Institute, USA by accelerator mass spectrometeric analysis.
Total bacterial counts (TC) and bacterial colony forming units (CFU’s) were determined for per g sample. The procedure by Kuwae and Hosokawa (Reference Kuwae and Hosokawa1999) was followed to measure total bacterial counts in the samples. One g soil sediments were aseptically added to 5 ml of filter-sterilised saline and vortexed thoroughly to dislodge the microbial cells from the sediment grains. One ml of this suspension was mixed with 20 μl DAPI (4′, 6-Diamidino-2-phenylindole) solution (0.25% w/v in sterile distilled water) and taken in a sterile vial. After keeping in the dark for ~30 minutes, the sample was filtered on to a 0.2 μm Nuclepore polycarbonate track etched membrane filter. The filter was rinsed with a few drops of saline to remove the unbound DAPI and observed under a epifluorescence microscope (BX-51, Olympus, Japan), using non-fluorescent immersion oil. Bacterial cells appearing as bright blue spots against a dark background were manually counted in epi-fluorescence research microscope and number of cells per g sediments calculated. Culturable bacteria were enumerated using the spread plate method on Nutrient Agar (NA), 1/10 Nutrient Agar (1/10 NA) media, Marine Agar and 1/10 Marine Agar (pH 7.0 and 9.0).
Results and discussion
The sediments around Brøggerhalvøya were analysed for elements belonging to the alkali metal group such as Cs, Li and Rb; alkaline earth metal group such as Be, Ba and Sr; transition metal group such as Ag, Cd, Co, Cr, Cu, Fe, Mn, Ni, V, and Zn; other metal group such as Bi, Pb and Tl; non-metal group such as As; and Actinide element such as U. Their concentrations in each of the locations are given in Table 1 together with standard deviations based on triplicate readings. In the sediment samples studied, the elements were present in variable concentrations (Figs 2, 3) on both sides of the peninsula. Although no comparative studies have been published for the region, a study by Larsen and others (Reference Larsen, Kristensen, Asmund and Bjerregaard2001) in the Maarmorilik region of west Greenland observed that the levels of zinc and lead in the surrounding fjord systems were high affecting the marine biota of the area. In another study on local pollution and glacier induced sedimentation in two fjords of Svalbard (Adventfjord and Grønfjord) it was observed that the concentration of polycyclic aromatic hydrocarbons and chlorinated hydrocarbons was several times higher than the background values as a result of terrestrial water drainage and industrial activities (Holte and others Reference Holte, Dahle, Gulliksen and Næs1996).
Fig. 2. Elemental concentrations of Fe, Mn, Ba, Cr, V, Zn, Rb, Sr, Ni, Li and Cu.
Fig. 3. Elemental concentrations of Co, As, Pb, Cs, Be, U, Ag, Tl, In, Cd and Bi.
Elemental concentration at different locations on Kongsfjorden and Forlandsendet side of Brøggerhalvøya
The average values of elements in decreasing order of concentration in the Kongsfjorden side of Brøggerhalvøya were Fe> Mn> Ba > V > Zn > Sr > Rb > Cr > Li > Ni > As > Pb > Cu > Co > Cs >Ag > Be > U> Bi >Tl > Cd (Table 1). Nineteen sampling sites (KB-0, KB-2, KB-3, V-1, E-4, M-12 and TS13 to TS25) at Kongsfjorden side of Brøggerhalvøya showed variability in concentration of different elements (Table 1).
Three sampling sites (B, C and D) are located in water at the opposite side of Brøggerhalvøya facing towards Forlandsendet. The elements in decreasing order of their concentration on the Forlandsendet side of Brøggerhalvøya were Fe > Ba >Mn > V> Sr > Zn > Rb > Cr > Li > Ni > Pb > Cu > As > Co > Cs > Be > U> Tl > Bi > Cd (Table 1).
The coastal outcrop on the Forlandsendet side of Brøggerhalvøya has elements in decreasing order of concentration: Fe > Mn > Cr > Sr > Ba > Rb > Cr > Zn > V > Rb > Ni > Li > Co > Cu > As > Pb > Cs > Be > Cd > Tl > U > Bi (Table 1). The levels of the metals varied in the top layer (recent), the middle (12,496BP), and the bottom layer (42,500BP) in this coastal outcrop (Table 1).
The distribution of metals on both side of Brøggerhalvøya is influenced by many factors such as microbial activity, different water masses, glacier activity, ice cover in the area and mountain terrain. The melt water and inorganic particles are mainly accumulated in Kongsfjorden due to glacier activities (Svendsen and others Reference Svendsen2002). The sampling site V-1 is close to the Kronebreen and Kongsvegen glaciers, where the sedimentation rate is very high. Though the sampling sites KB-3, TS-14 and TS-19 are located away from direct runoffs from the glaciers, the higher metal concentrations at these sites may be due to factors such as different scientific-logistics activities at Ny-Alesund harbor, bacterial activity, deposition of eroded materials from Blomstrandhalvøya and mountainous areas. The site KB0, located out of Kongsfjorden area, showed comparatively lower concentrations of metals than the other sites in the inner part of Kongsfjorden.
Distribution of trace metals and its comparison with previous studies
In the current study, the concentration of trace metals in Kongsfjorden range from 0.07 to 0.35 mg/kg for Cd, 16.65 to 78.54mg/kg for Cr, 8.57 to 17.35 mg/kg for Co, 14.78 to 24.86 mg/kg for Cu, 8.82 to 26.82 mg/kg for Pb, 230.56 to 457.23 mg/kg for Mn, 13.92 to 36.19 mg/kg for Ni and 61.73 to 132.32 mg/kg for Zn (Table 1). The concentrations of the elements varied at different locations in Kongsfjorden.
The concentrations of trace metals in the Forlandsendet side of Brøggerhalvøya are 0.17 to 0.19 mg/kg for Cd, 57.41 to 74.77 mg/kg for Cr, 8.33 to 10.69 mg/kg for Co, 18.2 to 22.84 mg/kg for Cu, 19.29 to 22.95 mg/kg Pb, 209.31 to 263.26 mg/kg for Mn, 28.83 to 34.95 mg/kg for Ni, and 88.31 to 117.72 mg/kg for Zn, respectively (Table 1). The trace metal concentrations at the coastal outcrop ranged from 0.17 to 0.35 mg/kg for Cd, 33.46 to 207.53 mg/kg for Cr, 11.76 to 32.98 mg/kg for Co, 24.26 to 31.77 mg/kg for Cu, 6.91 to 21.06 mg/kg for Pb, 445.59 to 461.03 mg/kg for Mn, 30.95 to 43.28 mg/kg for Ni and 67.91 to 114.52 mg/kg for Zn, respectively (Table 1).
The Kongsfjorden side of Brøggerhalvøya has higher levels of trace metals (Cd, Cr, Co, Cu, Pb, Mn, Ni, Zn) than the three sites (B, C and D) on the Forlandsendet side of Brøggerhalvøya. However, other trace metals (Cd, Cr, Co, Cu, Mn, Ni, and Zn) except lead (Pb) are highest in the coastal out crop.
AMAP Assessment 2002 (AMAP 2005) focused on Hg, Pb and Cd which are hazardous to living organisms in the Arctic. In the current study, higher concentrations of Pb and Cd were recorded at site E-4 and TS-13, respectively. The concentrations of Cd and Pb determined in the present study are lower than the data from Chukchi Sea (Ma and others Reference Ma, Zeng, Chen, He, Yin, Zeng and Zeng2008). Cu, Pb and Zn concentrations were lower than the data previously reported in other Arctic areas such as Alaska (AMAP Assessment 2002), Laptev Sea (Holemann and others Reference Holemann, Sehirmaeher, Kassens and Prange1999), Kongsfjorden (Lu and others Reference Lu, Cai, Wang, Yin and Yang2012) and Cryoconites, Svalbard (Singh and others Reference Singh, Sharma, Gawas, Upadhyay, Naik, Pedneker and Ravindra2012). The concentration of Cr was also found to be lower than previous studies at Kongsfjorden (Lu and others Reference Lu, Cai, Wang, Yin and Yang2012), Beaufort Sea (Sweeney and Sathy-Naidu Reference Sweeney and Sathy-Naidu1989), Chukchi Sea (Shang Reference Shang2008; Ma and others Reference Ma, Zeng, Chen, He, Yin, Zeng and Zeng2008), East Siberia Sea (Presley Reference Presley1997), East Greenland (Naidu and others Reference Naidu, Blanchard, Kelley, Goering, Hameedi and Baskaran1997), Kara Sea (Esnough Reference Esnough1996), Laptev Sea (Holemann and others Reference Holemann, Sehirmaeher, Kassens and Prange1999) and Pechora Sea (Loring and others Reference Loring, Naes, Dahle, Matishov and Illin1995).
In the present study Cr, and Cu are lower than reported from the northeastern Chukchi Sea (Naidu and others Reference Naidu, Blanchard, Kelley, Goering, Hameedi and Baskaran1997), Beaufort Sea inner shelf (Sweeney and Sathy-Naidu Reference Sweeney and Sathy-Naidu1989), Laptev Sea (Holemann and others Reference Holemann, Sehirmaeher, Kassens and Prange1999) and Kongsfjorden (Lu and others Reference Lu, Cai, Wang, Yin and Yang2012) (Table 2). Compared to the current study the base line data of terrestrial habitats (glacier ice core and lichens) of Svalbard (Singh and others Reference Singh, Sharma, Gawas, Upadhyay, Naik, Pedneker and Ravindra2012, Reference Singh, Sharma, Gawas-Sakhalkar, Naik, Upadhyay, Mulik, Bohare and Ravindra2013) showed lower concentrations of metals. Lu and others (Reference Lu, Cai, Wang, Yin and Yang2012) reported higher concentration of three trace metals (Cr, Cu and Pb) in the sediments of Kongsfjord and concluded that probably the west Spitsbergen current (WSC) brings Pb from low and middle latitudes to the Arctic.
Table 2. Comparison of the present study with published data at different habitats of Arctic.
*Ice core values are in (μg/kg)
Crustal enrichment factors
To evaluate the contribution of the elements from natural sources the crustal input values were calculated using Fe as a reference element. The mean metal to Fe ratio was used to determine the percent contribution by individual metals using standard continental crustal values as described by Shaw and others (Reference Shaw, Reilly, Muysson, Pattenden and Campbell1967, Reference Shaw, Dostal and Keays1976) based on studies on the Canadian Precambrian shield. For elements Ag, As and Cs, as no estimate was available in Shaw and others (Reference Shaw, Reilly, Muysson, Pattenden and Campbell1967, Reference Shaw, Dostal and Keays1976), baseline data of upper continental crust as recommended by Rudnick and Gao (Reference Rudnick, Gao, Holland and Turekian2003) were considered. Providing appropriate space for variation in the crustal composition, the enrichment factors within the range 0.1 to 10 were considered as a contribution from crustal source while those above 10 were considered as enriched from other natural and/or anthropogenic sources in addition to the crustal material (Dasch and Wolff Reference Dasch and Wolff1989; Veysseyre and others Reference Veysseyre, Moutard, Ferrari, van de Velde, Barbante, Cozzi, Capodaglio and Boutron2001). The mean crustal enrichment factor (EF) values of all metals at each sampling location have been graphically represented (Fig 4). Results indicate that most of the elements were sourced from crustal inputs with no enrichment by anthropogenic sources.
Fig. 4. Mean crustal enrichment factors for the different metals at different sampling locations 1–25 (B = 1, C = 2, D = 3, KB0 = 4, KB2 = 5, KB3 = 6, V1 = 7, E4 = 8, M12 = 9. TS 13 to TS 25 correspond to locations 10 to 22 respectively. CT = 23, CM = 24,CB = 25)
In the present study, it is observed that the major crustal input of elements in the sediment samples probably comes from the glacial discharge along both the sides of the peninsula. Large numbers of glaciers, present on the peninsula, are highly sensitive to climate change (Fleming and others Reference Fleming, Dowdeswel and Oerlemans1997; Nowak and Hodson Reference Nowak and Hodson2013). Recent global warming events have caused considerable melting of the glaciers leading to draining down of huge amounts of glacial ice into the adjacent waters along with terrestrial sediments. Fjords being an important sink of these wash down materials from the glaciers and river erosion result in accumulation of the sediments in basins. The inputs from the large tidal glaciers create steep environmental gradients in sedimentation along the length of the water body.
Bacterial deposition
In the present study, bacterial count in the sediment samples was investigated through enumeration by both direct and culturable methods. The total cell counts varied from 3.30 × 105 to 3.02 × 106 per g soil sediment. These values were comparable to that reported by Junge and others (Reference Junge, Imhoff, Staley and Deming2002) in the Arctic sea ice (5.4 × 104 to 2.4 × 106 cells/ml) and that reported by Amato and others (Reference Amato, Hennebelle, Magand, Sancelme, Delort, Barbante, Boutron and Ferrari2007) from nearby Kongsvegen glacier (2 × 105 cells/ml).
The culturability of the bacterial cells varied on the two sides of the peninsula. It was between 5 to 54% on the Forlandsendet side of Brøggerhalvøya and between 0.01 to 0.69% on the Kongsfjorden side of Brøggerhalvøya. It is noteworthy that the Forlandsendet side is the less disturbed coast of the Brøggerhalvøya, compared to the Kongsfjorden side of the peninsula which has more tourism, sampling and research activities. Srinivas and others (Reference Srinivas, Nageswara, Rao, Vishnu, Vardhan Reddy, Pratibha, Sailaja, Kavya, Hara Kishore, Begum, Singh and Shivaji2009) have also observed that bacterial viable counts varied only marginally (0.5 × 103 – 1.3 × 104 cfu/g sediment) in the sediments from the innermost point Kongsfjorden to the outermost point. Bacterial activity and sediment composition has mutual effects. The role of bacteria in degradation of massive sulphides has been studied at Citronen fjord, north Greenland (Langdahl and Elberling Reference Langdahl and Elberling1997). Bacteria play a major role in ecosystem functioning (Fenchel Reference Fenchel2011) through biogeochemical cycles of N and C. Therefore the study on sediment properties and bacteria together has an ecological significance. Pathways of carbon oxidation in fjord sediment of Svalbard are mainly by Fe (III)-reducing bacteria (Vandieken and other 2006). The concentration of Fe is highest on Kongsfjorden, Forlandsendet and at the coastal outcrop than other elements, this indicate that possibly Fe (III)-reducing bacteria are mainly responsible for such contribution.
Conclusion
The present work, based on calculation of the enrichment factors for various elements, provides evidence that the sediments in the waters adjacent to the Brøggerhalvøya peninsula contain elements solely of crustal origin. These sediments have probably been deposited there from adjoining landmasses by the process of glacier weathering and microbial activities. Iron was the most abundant element in all the sites followed by Mn, Ba, Cr and others. Probably Fe and Mn reducing bacteria are mainly responsible for mineralisation in Svalbard. The bacterial concentration in these sediments is high with percent culturability values lower on the Kongsfjorden side than the other side of the peninsula. The study also confirms that the environment indeed contains these elements that have accumulated over a period of time. Future studies needs to be carried out to secure a better insight of microbial diversity and biogeochemical cycle of the region. This is NCAOR contribution no. 02/2015.
Acknowledgments
We are grateful to the Director, NCAOR for encouragement and research facilities. We are also thankful to the Director, National Research Centre for Grapes, Pune, India for analytical facilities. The authors are thankful to the Norwegian Polar Institute for the map. Thanks are also due to Dr Sunil Mundra and Dr Varun Shah for technical help. They are also grateful to reviewers of this article for valuable comments and suggestions. This is NCAOR contribution no. 02/2015.
