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Trace metals in surface water from the Great Barrier Reef
Marine Pollution Bulletin
0025-326X/86 $3.00+0.00 O 1986 Pergamon Press Ltd.
Marine Pollution Bulletin, Vol. 17, No. 3, pp. 96-98, 1986 Printed in Great Britain
Trace Metals in Surface Water from the Great Barrier Reef G. R. W. DENTON and C. BURDON-JONES
Department of Marine Biology, School of Biological Sciences, James Cook University of North Queensland. Qld. 481L Australia
Filtered (0.45 pm), unacidified, surface seawater samples, collected at 3-monthly intervals for 9 months from three locations within the Great Barrier Reef Province, were analysed for zinc, copper, nickel, cadmium and lead by atomic absorption spectroscopy (air/acetylene flame) following Chelex-100 (ammonium form) extraction. Mean levels of each metal ranged from 0.03-0.35; 0.11-0.24; 0.06-0.16; <0.01-0.06; all less than 0.06 lxg I-t respectively. Significant interIocational differences were observed for copper and nickel and clear temporal trends were identified for copper (location-dependent) and cadmium.
The spatial and temporal variability of zinc, copper, nickel, cadmium and lead in surface waters from locations within the northern (Lizard Island), central (Orpheus Island) and southern (Heron Island) sections of the Great Barrier Reef were examined (Fig. 1). The purpose of the study was to establish reliable baseline data with which future findings may be compared and evaluated. Methods At sites 1-4, seawater samples were taken at 3-monthly intervals from April 1982 to January 1983. Samples from site 5 were collected in October 1982 and January 1983 only. All samples were taken approximately 500 m seaward of the reef edge at each site. They were collected from the bow of a small boat (forward speed < 1 knot) in 5 I. polypropylene bottles held approximately 10 cm below the surface. In the laboratory each sample was filtered through acid-cleaned, 0.45 ~trn Millipore membranes within 1-2 h of collection. Four 3.25 I. sub-samples were then passed unacidified through columns (3X 1.5 cm) of the ionexchange resin, Chelex-100 (100-200 mesh, ammonium form), at a flow rate not exceeding 2 ml min -~. The metals retained by the resin were eluted with 50 ml of 2 N silica-glass distilled, nitric acid and 25 ml of double-distilled water into a 250 ml silica-glass flask, gently evaporated to dryness on a hot plate, redissolved in 5 ml of 2 N nitric acid and analysed for zinc, copper, cadmium, nickel and lead, by atomic absorption spec96
troscopy. Bl.ank columns were also eluted to check the purity of reagents used. Results and D i s c u s s i o n The data together with the temperatures and salinities of surface waters from each site are summarized in Table 1. The double data sets for sites 3 (April-January) and 5 (April and July) are for samples collected 48 h apart and provide a measure of the short-term temporal fluctuations in dissolved metal levels. Lead was the only element examined that was consistently below the limit of analytical detection (0.06 gtg 1-~). Inter-locational differences between the grand mean values for zinc, copper and nickel were determined by one-way analysis of variance and an appropriate multiple range test (Zar, 1974). Data sets were pooled for sites 1 and 2 at Lizard Island and sites 4 and 5 at Heron Island to facilitate the statistical analysis. Both parametric and non-parametric tests gave similar results. Zinc concentrations showed comparatively large within- and between-site variations and statistical analysis failed to resolve significant inter-locational differences. Part of this variability was attributed to the analysis which, despite every precaution taken to standardize procedures and minimize contamination, frequently yielded highly variable results for replicate samples (i.e. coefficients of variation ranged from 956%). It is perhaps worth mentioning here that the relatively poor analytical precision for zinc after Chelex100 extraction confirms the earlier findings of Bruland et al. (1979). Replicate samples for copper and nickel gave better agreement and grand mean values for both metals were significantly higher (p<0.01) at Orpheus Island (site 3) than elsewhere examined. No doubt this partly reflects the close proximity of Orpheus Island to the coast and to major urban growth centres. It is also pertinent to note that both a copper and nickel refinery are located at Townsville some 50 km SE of Orpheus Island. Although to what extent these industries influence ambient metal levels in local waters is unknown. Small but nonetheless distinct temporal differences in mean copper levels were observed at sites 1-4 although these were clearly location dependant. At each site,
Volume 17/Number 3/March 1986
al
\
Fig. 1 Sampling locations along the Great Barrier Reef. The closed circles indicate the collection sites which are identified numerically.
differences between maximum and minimum mean copper values varied by a factor of 1.5 or less. Within-site variability for nickel was more pronounced with mean values varying by up to a factor of 2.3 at Orpheus Island. However, temporal trends for this metal were not readily identifiable. Cadmium appeared to be seasonally dependant with highest levels occurring at all locations at the end of the 1981/82 wet season (April). The substantial increase in mean cadmium levels from 0.03 to 0.06 p.g 1-~ in the surface waters at the Orpheus Island site is especially noteworthy and may have resulted from the washing out of atmospheric cadmium by heavy rain (12 cm in 24 h) which fell on the day preceding the second sample. If this was so, then a gradual decline in levels should have occurred as this input of cadmium was dispersed. The absence of comparable falls of rain thereafter until about mid-1983 could, therefore, account for the levels being below detection limits in the samples taken during October and the following January. The data presented here for zinc, copper, nickel and
cadmium are reflective of uncontaminated shelf waters and provide a useful point of reference for future trace metal surveillance studies conducted in the area. It is important to note however, that the analytical technique employed does not provide a measure of the total concentration for all metals considered and this should be taken into account when making comparative assessments. The work of Bruland et al. (1979) is especially relevant here and shows that Chelex-100, whilst removing virtually all of the cadmium present in seawater, only retains about 60% of the total zinc and copper and 70% of the total nickel (from samples collected at 0 and 25 m). These extraction efficiencies, when applied to the present data, give grand mean total concentrations ranging from 0.13 to 0.28 0g l-t for zinc, 0.22 to 0.32 pg 1-1 for copper and 0.11 to 0.17 0g 1-~ for nickel. These values, together with those given for cadmium in Table 1, compare favourably with levels reported for nonpolluted shelf waters elsewhere in the world (e.g. Bruland & Franks, 1981; Campbell & Loring, 1980; Mackay 1984). 97
Marine Pollution Bulletin TABLE 1
Trace metals in surface waters from the Great Barrier Reef (data are mean ± 1 standard deviation; ranges only given where means not quantifiable; r ~ 4) Location
Site Month
Temp. ('C)
Salin. (%0)
Zn
Metal levels ~ 1Cu
Ni
Cd
27.0 24.0 25.2 28.5
35.1 35.6 35.7 35.6
0.21± 0.02 0.10± 0.05 0.03±0.01 0.074-0.02
0.11 ± 0.01 0.15± 0.01 0.14±0.01 0.13+0.01
0.07± 0.02 0.08± 0.03 0.09±0.02 0.10±0.01
0.01 ± 0.01 0.014- 0.00 <0.01--<0.01 <0.01--<0.01
Lizard Island
1
April July Oct. Jan.
Lizard Island
2
April 27.0 35.3 July 23.5 35.6 Oct. 25.1 35.7 Jan. 28.0 35.6 Grand Mean (Sites 1 and 2)
0.12± 0.03 0.05± 0.02 0.03± 0.01 0.064-0.03 0.08
0.12± 0.01 0.15± 0.01 0.15+ 0.01 0.12±0.01 0.13
0.08± 0.01 0.10± 0.02 0.07± 0.01 0.10±0.02 0.09
0.03± 0.01 0.01± 0.00 <0.01-<0.01 <0.01-<0.01 NQ
Orpheus Island 3
April 28.2 35.7 April 28.0 35.4 July 20.5 35.9 July 21.0 36.5 Oct. 23.5 36.0 Oct. 25.0 36.2 Jan. 30.3 36.2 Jan. 29.8 36.1 Grand Mean (Site 3)
0.21± 0.07 0.12±0.03 0.10+0.01 0.19± 0.04 0.27± 0.05 0.07+ 0.03 0.06± 0.02 0.04±0.01 0.14
0.24± 0.01 0.22±0.01 0.17±0.02 0.19+ 0.02 0.16± 0.01 0.16± 0.01 0.18+ 0.00 0.17+0.01 0.18
0.13± 0.03 0.12±0.02 0.13±0.03 0.16+ 0.01 0.07± 0.03 0.09± 0.03 0.12± 0.03 0.11+0.01 0.12
0.03± 0.01 0.064.0.02 0.02±0.01 0.02+ 0.01 <0.01--<0.01 <0.01--<0.01 <0.01--<0.01 <0.01--<0.01 NQ
Heron Island
4
April April July July Oct. Jan.
0.35±0.09 0.17+ 0.08 0.23± 0.02 0.11± 0.01 0.22+0.02 0.09+ 0.05
0.13±0.01 0.12=1:0.01 0.14± 0.01 0.14± 0.01 0.15±0.01 0.15± 0.01
0.10±0.02 0.06± 0.02 0.07± 0.03 0.08± 0.02 0.09+0.01 0.07± 0.01
0.024.0.01 0.01+ 0.01 0.01+ 0.00 0.01± 0.00 <0.01+<0.01 <0.01--<0.01
Heron Island
5
Oct. 22.5 35.9 Jan. 25.5 36.0 Grand Mean (Sites 4 and 5)
0.104.0.05 0.14+0.05 0.17
0.15+0.01 0.16+0.01 0.14
0.10+0.01 0.08+0.02 0.08
<0.01-<0.01 <0.01--<0.01 NQ
26.2 25.8 21.1 21.0 22.5 26.0
36.0 35.9 36.2 36.2 35.9 36.1
N Q - Not quantifiable. N.B. Lead levels in surface waters from all sites were consistently below an analytical detection limit of 0.06 lag 1- ~.
This work was supported by an Australian Marine Sciences and Technologies Award (nos. 80-0078R). We thank the staff of Lizard Island, Orpheus Island and Heron Island Research Stations for their invaluable cooperation and assistance.
Bruland, K. W. & Franks, R. P. (1981). Mn, Ni, Cu, Zn, and Cd in the western North Atlantic. In: Trace Metals in Seawater(C. W. Wong, E. Boyle, K. W. Bruland, J. D. Burton & E. D. Goldberg (Eds)). Plenum Press, New York, 1983, pp. 395-414.
Bruland, K. W., Franks, R. P., Knauer, G. A. & Martin, J. H. (1979). Sampling and analytical methods for the determination of copper, cadmium, zinc and nickel at the nanograms per litre level in sea water. Anal. chim. Acta 105,233-245. Campbell, J. A. & Loring, D. H. (1980). Baseline levels of heavy metals in the waters and sediments of Baffin Bay. Mar. Pollut. Bull. 11, 257261. Mackey, D. (1984). Trace metals and the productivity of shelf waters off north west Australia. Aust. Z mar. Freshwat. Res. 35, 505-516. Zar, J. H. (1974). Biostatistical Analysis (W. D. McElroy & C. E Swanson (Eds)). Englewood Cliffs, Prentice-Hall.
MarinePollutionBufletin,Vol.17,No. 3, pp.98-107, 1986 PrintedinGreatBritain
0025-326X/86 $3.00+0.00 01986 PergamonPressLtd.
Trace Metals in Algae from the Great Barrier Reef G. R. W. DENTON and C. BURDON-JONES
Department of Marine Biology, School of Biological Sciences, James Cook University of North Queensland, Townsville, Qld. 4811,Australia. Zinc, copper, cadmium, nickel, lead and mercury concentrations were examined in 48 species of algae from the Great Barrier Reef. In general the data showed 98
considerable inter- and intra-specific variation with mean levels for each metal ranging from 0.27 to 38.6; 0.74 to 11.2; 0.08 to 2.2; 0.41 to 46.1; < 0 . 4 5 to 6.7,
0025-326X/86 $3.00+0.00 O 1986 Pergamon Press Ltd.
Marine Pollution Bulletin, Vol. 17, No. 3, pp. 96-98, 1986 Printed in Great Britain
Trace Metals in Surface Water from the Great Barrier Reef G. R. W. DENTON and C. BURDON-JONES
Department of Marine Biology, School of Biological Sciences, James Cook University of North Queensland. Qld. 481L Australia
Filtered (0.45 pm), unacidified, surface seawater samples, collected at 3-monthly intervals for 9 months from three locations within the Great Barrier Reef Province, were analysed for zinc, copper, nickel, cadmium and lead by atomic absorption spectroscopy (air/acetylene flame) following Chelex-100 (ammonium form) extraction. Mean levels of each metal ranged from 0.03-0.35; 0.11-0.24; 0.06-0.16; <0.01-0.06; all less than 0.06 lxg I-t respectively. Significant interIocational differences were observed for copper and nickel and clear temporal trends were identified for copper (location-dependent) and cadmium.
The spatial and temporal variability of zinc, copper, nickel, cadmium and lead in surface waters from locations within the northern (Lizard Island), central (Orpheus Island) and southern (Heron Island) sections of the Great Barrier Reef were examined (Fig. 1). The purpose of the study was to establish reliable baseline data with which future findings may be compared and evaluated. Methods At sites 1-4, seawater samples were taken at 3-monthly intervals from April 1982 to January 1983. Samples from site 5 were collected in October 1982 and January 1983 only. All samples were taken approximately 500 m seaward of the reef edge at each site. They were collected from the bow of a small boat (forward speed < 1 knot) in 5 I. polypropylene bottles held approximately 10 cm below the surface. In the laboratory each sample was filtered through acid-cleaned, 0.45 ~trn Millipore membranes within 1-2 h of collection. Four 3.25 I. sub-samples were then passed unacidified through columns (3X 1.5 cm) of the ionexchange resin, Chelex-100 (100-200 mesh, ammonium form), at a flow rate not exceeding 2 ml min -~. The metals retained by the resin were eluted with 50 ml of 2 N silica-glass distilled, nitric acid and 25 ml of double-distilled water into a 250 ml silica-glass flask, gently evaporated to dryness on a hot plate, redissolved in 5 ml of 2 N nitric acid and analysed for zinc, copper, cadmium, nickel and lead, by atomic absorption spec96
troscopy. Bl.ank columns were also eluted to check the purity of reagents used. Results and D i s c u s s i o n The data together with the temperatures and salinities of surface waters from each site are summarized in Table 1. The double data sets for sites 3 (April-January) and 5 (April and July) are for samples collected 48 h apart and provide a measure of the short-term temporal fluctuations in dissolved metal levels. Lead was the only element examined that was consistently below the limit of analytical detection (0.06 gtg 1-~). Inter-locational differences between the grand mean values for zinc, copper and nickel were determined by one-way analysis of variance and an appropriate multiple range test (Zar, 1974). Data sets were pooled for sites 1 and 2 at Lizard Island and sites 4 and 5 at Heron Island to facilitate the statistical analysis. Both parametric and non-parametric tests gave similar results. Zinc concentrations showed comparatively large within- and between-site variations and statistical analysis failed to resolve significant inter-locational differences. Part of this variability was attributed to the analysis which, despite every precaution taken to standardize procedures and minimize contamination, frequently yielded highly variable results for replicate samples (i.e. coefficients of variation ranged from 956%). It is perhaps worth mentioning here that the relatively poor analytical precision for zinc after Chelex100 extraction confirms the earlier findings of Bruland et al. (1979). Replicate samples for copper and nickel gave better agreement and grand mean values for both metals were significantly higher (p<0.01) at Orpheus Island (site 3) than elsewhere examined. No doubt this partly reflects the close proximity of Orpheus Island to the coast and to major urban growth centres. It is also pertinent to note that both a copper and nickel refinery are located at Townsville some 50 km SE of Orpheus Island. Although to what extent these industries influence ambient metal levels in local waters is unknown. Small but nonetheless distinct temporal differences in mean copper levels were observed at sites 1-4 although these were clearly location dependant. At each site,
Volume 17/Number 3/March 1986
al
\
Fig. 1 Sampling locations along the Great Barrier Reef. The closed circles indicate the collection sites which are identified numerically.
differences between maximum and minimum mean copper values varied by a factor of 1.5 or less. Within-site variability for nickel was more pronounced with mean values varying by up to a factor of 2.3 at Orpheus Island. However, temporal trends for this metal were not readily identifiable. Cadmium appeared to be seasonally dependant with highest levels occurring at all locations at the end of the 1981/82 wet season (April). The substantial increase in mean cadmium levels from 0.03 to 0.06 p.g 1-~ in the surface waters at the Orpheus Island site is especially noteworthy and may have resulted from the washing out of atmospheric cadmium by heavy rain (12 cm in 24 h) which fell on the day preceding the second sample. If this was so, then a gradual decline in levels should have occurred as this input of cadmium was dispersed. The absence of comparable falls of rain thereafter until about mid-1983 could, therefore, account for the levels being below detection limits in the samples taken during October and the following January. The data presented here for zinc, copper, nickel and
cadmium are reflective of uncontaminated shelf waters and provide a useful point of reference for future trace metal surveillance studies conducted in the area. It is important to note however, that the analytical technique employed does not provide a measure of the total concentration for all metals considered and this should be taken into account when making comparative assessments. The work of Bruland et al. (1979) is especially relevant here and shows that Chelex-100, whilst removing virtually all of the cadmium present in seawater, only retains about 60% of the total zinc and copper and 70% of the total nickel (from samples collected at 0 and 25 m). These extraction efficiencies, when applied to the present data, give grand mean total concentrations ranging from 0.13 to 0.28 0g l-t for zinc, 0.22 to 0.32 pg 1-1 for copper and 0.11 to 0.17 0g 1-~ for nickel. These values, together with those given for cadmium in Table 1, compare favourably with levels reported for nonpolluted shelf waters elsewhere in the world (e.g. Bruland & Franks, 1981; Campbell & Loring, 1980; Mackay 1984). 97
Marine Pollution Bulletin TABLE 1
Trace metals in surface waters from the Great Barrier Reef (data are mean ± 1 standard deviation; ranges only given where means not quantifiable; r ~ 4) Location
Site Month
Temp. ('C)
Salin. (%0)
Zn
Metal levels ~ 1Cu
Ni
Cd
27.0 24.0 25.2 28.5
35.1 35.6 35.7 35.6
0.21± 0.02 0.10± 0.05 0.03±0.01 0.074-0.02
0.11 ± 0.01 0.15± 0.01 0.14±0.01 0.13+0.01
0.07± 0.02 0.08± 0.03 0.09±0.02 0.10±0.01
0.01 ± 0.01 0.014- 0.00 <0.01--<0.01 <0.01--<0.01
Lizard Island
1
April July Oct. Jan.
Lizard Island
2
April 27.0 35.3 July 23.5 35.6 Oct. 25.1 35.7 Jan. 28.0 35.6 Grand Mean (Sites 1 and 2)
0.12± 0.03 0.05± 0.02 0.03± 0.01 0.064-0.03 0.08
0.12± 0.01 0.15± 0.01 0.15+ 0.01 0.12±0.01 0.13
0.08± 0.01 0.10± 0.02 0.07± 0.01 0.10±0.02 0.09
0.03± 0.01 0.01± 0.00 <0.01-<0.01 <0.01-<0.01 NQ
Orpheus Island 3
April 28.2 35.7 April 28.0 35.4 July 20.5 35.9 July 21.0 36.5 Oct. 23.5 36.0 Oct. 25.0 36.2 Jan. 30.3 36.2 Jan. 29.8 36.1 Grand Mean (Site 3)
0.21± 0.07 0.12±0.03 0.10+0.01 0.19± 0.04 0.27± 0.05 0.07+ 0.03 0.06± 0.02 0.04±0.01 0.14
0.24± 0.01 0.22±0.01 0.17±0.02 0.19+ 0.02 0.16± 0.01 0.16± 0.01 0.18+ 0.00 0.17+0.01 0.18
0.13± 0.03 0.12±0.02 0.13±0.03 0.16+ 0.01 0.07± 0.03 0.09± 0.03 0.12± 0.03 0.11+0.01 0.12
0.03± 0.01 0.064.0.02 0.02±0.01 0.02+ 0.01 <0.01--<0.01 <0.01--<0.01 <0.01--<0.01 <0.01--<0.01 NQ
Heron Island
4
April April July July Oct. Jan.
0.35±0.09 0.17+ 0.08 0.23± 0.02 0.11± 0.01 0.22+0.02 0.09+ 0.05
0.13±0.01 0.12=1:0.01 0.14± 0.01 0.14± 0.01 0.15±0.01 0.15± 0.01
0.10±0.02 0.06± 0.02 0.07± 0.03 0.08± 0.02 0.09+0.01 0.07± 0.01
0.024.0.01 0.01+ 0.01 0.01+ 0.00 0.01± 0.00 <0.01+<0.01 <0.01--<0.01
Heron Island
5
Oct. 22.5 35.9 Jan. 25.5 36.0 Grand Mean (Sites 4 and 5)
0.104.0.05 0.14+0.05 0.17
0.15+0.01 0.16+0.01 0.14
0.10+0.01 0.08+0.02 0.08
<0.01-<0.01 <0.01--<0.01 NQ
26.2 25.8 21.1 21.0 22.5 26.0
36.0 35.9 36.2 36.2 35.9 36.1
N Q - Not quantifiable. N.B. Lead levels in surface waters from all sites were consistently below an analytical detection limit of 0.06 lag 1- ~.
This work was supported by an Australian Marine Sciences and Technologies Award (nos. 80-0078R). We thank the staff of Lizard Island, Orpheus Island and Heron Island Research Stations for their invaluable cooperation and assistance.
Bruland, K. W. & Franks, R. P. (1981). Mn, Ni, Cu, Zn, and Cd in the western North Atlantic. In: Trace Metals in Seawater(C. W. Wong, E. Boyle, K. W. Bruland, J. D. Burton & E. D. Goldberg (Eds)). Plenum Press, New York, 1983, pp. 395-414.
Bruland, K. W., Franks, R. P., Knauer, G. A. & Martin, J. H. (1979). Sampling and analytical methods for the determination of copper, cadmium, zinc and nickel at the nanograms per litre level in sea water. Anal. chim. Acta 105,233-245. Campbell, J. A. & Loring, D. H. (1980). Baseline levels of heavy metals in the waters and sediments of Baffin Bay. Mar. Pollut. Bull. 11, 257261. Mackey, D. (1984). Trace metals and the productivity of shelf waters off north west Australia. Aust. Z mar. Freshwat. Res. 35, 505-516. Zar, J. H. (1974). Biostatistical Analysis (W. D. McElroy & C. E Swanson (Eds)). Englewood Cliffs, Prentice-Hall.
MarinePollutionBufletin,Vol.17,No. 3, pp.98-107, 1986 PrintedinGreatBritain
0025-326X/86 $3.00+0.00 01986 PergamonPressLtd.
Trace Metals in Algae from the Great Barrier Reef G. R. W. DENTON and C. BURDON-JONES
Department of Marine Biology, School of Biological Sciences, James Cook University of North Queensland, Townsville, Qld. 4811,Australia. Zinc, copper, cadmium, nickel, lead and mercury concentrations were examined in 48 species of algae from the Great Barrier Reef. In general the data showed 98
considerable inter- and intra-specific variation with mean levels for each metal ranging from 0.27 to 38.6; 0.74 to 11.2; 0.08 to 2.2; 0.41 to 46.1; < 0 . 4 5 to 6.7,