Trace metals in sediments from Torres Strait and the Gulf ofPapua: concentrations, distribution and water circulation patterns

David Haynes a,*, Donna Kwan b

a Great Barrier Reef Marine Park Authority, P.O. Box 1379, Townsville 4810, Australiab Tropical Environmental Science and Geography, James Cook University, Townsville 4811, Australia

Keywords: Heavy metals; Torres Strait; Marine pollution; Sediments; Great Barrier Reef; Fly River; Ok Tedi

Torres Strait is a relatively shallow (typically <20m),tropical epicontinental seaway that separates the Aus-

tralian mainland from Papua New Guinea (Fig. 1). The

region is characterised by numerous continental islands

and coral reefs and has been the subject of a number of

biological and physico-chemical investigations over the

last 15 years, principally to investigate the estuarine andmarine impacts of large-scale mining activities that have

been carried out in the Papuan highlands over the last 20

years. In particular, gold and copper mining on the Ok

Tedi River (a tributary of the Fly River) is estimated to

contribute 750,000 tonnes per day of copper-rich mine

tailings and 90,000 tonnes of sediment per day to the

river (Apte and Day, 1998). Past studies have concluded

that the impact of the Fly River discharge on local tracemetal concentrations is restricted to the northern Torres

Strait (Alongi et al., 1991; Baker and Harris, 1991;

Baker et al., 1990; Gladstone, 1996). However, elevated

concentrations of certain metals reported in seafoods

commonly eaten by Torres Strait Islanders has promp-

ted ongoing monitoring of Torres Strait metal concen-

trations (Dight and Gladstone, 1993; Gladstone, 1996;

Evans-Illidge, 1997). The results of the most recentsurvey of metal concentrations in sediments from the

Gulf of Papua and Torres Strait are presented here.

Sediment samples were collected from 28 sites across

Torres Strait (northern, central and southern Torres

Strait) and from the Gulf of Papua in February 2000

(Fig. 1). All sediment samples were collected opportu-

nistically along the route of a proposed natural gas

pipeline between Papua New Guinea and Australiaduring an environmental assessment phase of the pipe-

line project (NSR, 1997). Sediment samples were col-

lected using a vibrocore. Sediments for metals analyses

were selectively retrieved from the top portion of the core

(representing approximately 2–3 cm of surficial bottom

sediments) and placed in acid washed plastic containers.

Sediment samples were frozen following collection.

Heavy metals analyses were performed at the NATA

certified laboratory of the Queensland Department of

Natural Resources, Brisbane. Frozen sediments were

transported to the analytical laboratory where the sam-ples were thawed and ground to <50 lm using a shatter-box grinding mill. Ground sediment samples were

pelleted using the pressed powder technique (Gladstone,

1996) and analysed by X-ray fluorescence for Al, As, Co,

Cr, Cu, Fe, Mn, Ni, Pb, Si, Sr and Zn concentrations. Cd

and Hg determination samples were digested with nitric

and hydrochloric acids (6:2) following 2 h exposure to a

steam bath. Cadmium was analysed by graphite furnaceatomic adsorption spectrometry (AAS), and mercury by

hydride generation AAS. Sediment calcium carbonate

content was determined by a weight loss gravimetric

method (Blakemore et al., 1987).

Blanks and certified reference materials (Marine

Sediment Mess-2, National Research Council, Canada)

were analysed concurrently with sediment samples to

ensure consistency and accuracy of recoveries over metalanalyses (Table 1). Metal data were graphed and in-

spected for gross deviations from normality and where

necessary, transformed (log10) prior to analysis. Non-

detectable values were set at half the detection limit for

that metal for statistical analyses purposes. Pearson

correlation co-efficients and their associated Bonferroni-

adjusted probabilities were calculated for sediment

physico-chemical parameters. Sediment metal data werestandardised to Z scores and an agglomerative hierar-

chical algorithm using complete clustering used to clas-

sify the sediment metal data and principal component

analysis (PCA) used to ordinate the data. Euclidean

distances were utilized to calculate dissimilarities. The

presence of natural groupings in the data was defined by

concurrence in both the classification and the ordination

analyses (Clarke and Warwick, 1994). Differences inmetal concentrations between sampling regions defined

*Corresponding author. Tel.: +61-747-500700; fax: +61-747-

726093.

E-mail address: d.haynes@gbrmpa.gov.au (D. Haynes).

Baseline / Marine Pollution Bulletin 44 (2002) 1296–1313 1309

by multivariate analysis were compared using one-way

analysis of variance (ANOVA). Significant differences in

metal concentrations were located using a Tukey HSD

multiple comparison test with an experiment-wise type 1

error probability of 0.05. All statistical computations

were carried out with the aid of the SYSTAT V7.0

package (Wilkinson, 1996).

Detectable concentrations of all metals analysed forwere present in Torres Strait sediments (Table 2). All

metals except strontium and cadmium were negatively

correlated with calcium carbonate concentrations and

positively correlated with aluminium, iron and silica

concentrations, and is indicative of their terrestrial origin

(Table 3). In contrast, both strontium and cadmium were

primarily associated with carbonates of marine origin.

The first two components of a PCA of standardisedsediment metal concentrations accounted for 82% of the

variance in the data (Table 4). The cluster dendrogram

and the PCA ordination separated sediment samples

into four distinct clusters (Fig. 2). These consisted of

samples collected in the Gulf of Papua, in Northern

Torres Strait (adjacent to the Fly River delta), a single

sample collected at the northern end of Dungeness

Reef (central Torres Strait) and samples collected incentral and southern Torres Strait (Fig. 3). Principal

component I (47% of the data variance) was associated

with all metals except cadmiumand arsenic, and principal

component II (35% of the data variance) was associated

with sediment arsenic and cadmium concentrations.

Average concentrations of sediment metals were

similar to those detected in past surveys of Torres Strait

(Table 5), although concentrations of arsenic, chromium

Fig. 1. Torres Strait and Gulf of Papua sediment sampling sites.

Table 1

Standard reference material (MESS-2) recoveries

Element Units (dry

weight)

SRM

recovery

SRM certi-

fied value

SRM stan-

dard deviation

CaCO3 % 98.6 100

Al % 8.36 8.57 0.26

Co mgkg�1 10.8 13.8 1.4

Cr mgkg�1 114 106 8

Cu mgkg�1 31.9 39.3 2

Fe % 4.39 4.35 0.22

Mn mgkg�1 368 365 21

Ni mgkg�1 55.4 49.3 1.8

Pb mgkg�1 21.7 21.9 1.2

Si % 25.6 27.80 1.10

Sr mgkg�1 150 125 10

Zn mgkg�1 173 172 16

Cd mgkg�1 0.234 0.24 0.01

Hg mgkg�1 0.099 0.092 0.009

As mgkg�1 19.3 20.7 0.8

1310 Baseline / Marine Pollution Bulletin 44 (2002) 1296–1313

and nickel were high enough to exceed sediment qualityguidelines (ANZECC, 2000) at a number of sites. Nickel

sediment concentrations were elevated (i.e. >21 mgkg�1

dry weight) at all Gulf of Papua sampling sites and all

but one of the northern Torres Strait sampling sites.

Similarly, sediment concentrations of chromium were

elevated (i.e. >80 mgkg�1 dry weight) at all Gulf sitesand at a majority of northern Torres Strait sampling

sites. Concentrations of arsenic were elevated (i.e. >20mgkg�1 dry weight) at approximately half of the

Gulf of Papua and northern Torres Strait sampling

sites. Average sediment metal and calcium carbonate

concentrations were significantly different between the

sampling regions defined in the multivariate analyses

Table 2

Torres Strait and Gulf of Papua sediment heavy metal concentrations

Sample no. CaCO3 Al Co Cr Cu Fe Mn Ni Pb Si Sr Zn Cd Hg As

1 11.9 7.38 18 94 16 5.28 1363 33 15 23.6 405 81 0.03 0.03 15.8

2 11.4 7.23 21 128 15 5.75 1362 34 20 23.4 363 85 0.03 0.05 22.4

3 3.5 9.68 19 95 29 5.45 955 41 24 24.5 179 113 0.02 0.07 20.6

4 7.3 9.14 15 88 18 4.93 638 42 34 22.8 262 108 0.03 0.06 11.9

5 44.6 4.76 <6 68 <8 3.71 990 28 12 16.1 832 57 0.03 0.03 32.2

6 44.1 5.7 <6 58 <8 2.72 404 23 15 15.6 1176 57 0.03 0.03 9.8

7 42 4.91 <6 80 <8 3.2 386 23 14 16.3 1116 56 0.03 0.03 11.8

8 19.7 6.99 12 98 <8 4.9 661 41 22 23 442 84 0.03 0.03 26.4

9 23.8 5.74 9 96 <8 4.44 510 35 21 23.5 607 81 0.02 0.03 14.3

10 38.4 4.54 <6 91 <8 4.1 572 26 23 18.3 810 62 0.03 0.02 23.5

11 36.7 3.17 <6 118 <8 3.6 382 19 17 20.2 749 46 0.02 0.02 21.5

12 55 2.69 <6 68 <8 3.16 282 11 8 13.5 1071 37 0.02 0.02 17.9

13 66.7 2.02 <6 51 <8 2.94 229 <10 6 9.34 1334 24 0.02 0.02 18.3

14 68.2 1.99 <6 42 <8 1.43 174 <10 8 9.07 1786 22 0.02 0.01 5.5

15 76.4 1.49 <6 32 <8 0.91 164 <10 6 6.37 2261 16 0.03 0.01 3

16 79.3 1.14 <6 32 <8 1.51 240 <10 9 5.33 2007 <12 0.03 0.01 6.3

17 82.8 1.19 <6 32 <8 1.81 229 <10 4 3.95 1628 13 0.05 0.01 15.9

18 84.2 1.04 <6 22 <8 1.89 370 <10 6 3.86 1733 13 0.04 0.01 16.1

19 IS 0.42 <6 21 <8 1.43 332 <10 <4 1.51 2117 16 0.06 <0.01 23

20 89.5 0.46 <6 14 <8 0.12 210 <10 6 1.85 1309 <12 0.11 <0.01 4.7

21 92.7 0.34 <6 12 <8 0.22 109 <10 7 1.09 2634 <12 0.05 <0.01 5.5

22 86 0.56 <6 17 <8 0.84 159 <10 12 2.34 2234 <12 0.03 <0.01 8

23 86.3 0.86 <6 26 <8 0.84 151 <10 9 3.02 2495 <12 0.04 <0.01 7.3

24 85.7 0.73 <6 25 <8 0.99 251 <10 9 2.89 2406 <12 0.04 <0.01 10.7

25 70.2 4.1 <6 42 <8 1.72 148 12 7 5.86 1089 14 0.05 0.02 17.4

26 87.7 0.71 <6 19 <8 0.71 163 <10 10 2.8 2247 <12 0.03 <0.01 7.9

27 74.4 0.39 <6 17 <8 0.71 150 <10 7 7.36 1867 <12 0.04 <0.01 15.7

28 51.6 1.37 <6 22 <8 2.34 166 <10 17 15.7 1233 <12 0.07 0.01 21

All metal concentrations mgkg�1 dry weight, CaCO3, Al, Fe, Si %.

Table 3

Pearson correlation coefficient matrix including Bonferroni adjusted

probabilities for sediment metal concentrations

Element CaCO3 Al Fe Si

Aluminium )0.945���

Iron )0.962��� 0.911���

Silica )0.986��� 0.890��� 0.951���

Strontium 0.900��� )0.863��� )0.890��� )0.892���

Cobalt )0.792��� 0.812��� 0.775��� 0.712��

Chromium )0.909��� 0.839��� 0.928��� 0.915���

Copper )0.665� 0.732��� 0.622 0.562

Manganese )0.800��� 0.791�� 0.841��� 0.758���

Nickel )0.941��� 0.962��� 0.911��� 0.907���

Lead )0.849��� 0.814��� 0.777��� 0.825���

Zinc )0.957��� 0.971��� 0.934��� 0.921���

Cadmium 0.413 )0.392 )0.470 )0.426Mercury )0.889��� 0.948��� 0.864��� 0.822���

Arsenic )0.574 0.477 0.674� 0.611

* 0:05 < p < 0:01.** 0:01 < p < 0:001.*** p < 0:001:

Table 4

Summary of PCA analysis of sediment metal concentrations

Element Component I Component II

Copper 0.931 0.026

Cobalt 0.909 0.226

Mercury 0.836 0.459

Aluminium 0.801 0.552

Zinc 0.774 0.600

Nickel 0.733 0.624

Lead 0.689 0.481

Manganese 0.686 0.503

Iron 0.640 0.750

Silica 0.616 0.737

Strontium )0.570 )0.705Chromium 0.541 0.774

Arsenic 0.014 0.805

Cadmium )0.174 )0.497

% Variance explained 46.8 35.0

Eigen value 10.308 1.145

Baseline / Marine Pollution Bulletin 44 (2002) 1296–1313 1311

(Table 6). Calcium carbonate concentrations increased

with increasing distance from the Gulf of Papua. Lowest

concentrations of strontium and cadmium were also

present in the Gulf of Papua and northern Torres Strait.

In contrast, concentrations of all other metals weresignificantly higher in sediments collected from the Gulf

of Papua and/or northern Torres Strait than in sedi-

ments collected from more southern sites in central and

southern Torres Strait.

Oceanographic studies have indicated that cur-

rent flow in the Torres Strait region is predominantly

east–west in the passages between reefs and island, but

otherwise tends to run north–south, along the GreatNorth-East Channel, parallel to Warrior Reefs (NSR,

1997; Wolanski et al., 1999). Oceanic circulation within

the Gulf of Papua is dominated by a clockwise gyre

generated as the northwards flowing Coral Sea Coastal

Current enters the Gulf along the eastern edge of Torres

Strait and exits to the north-east (Woolfe et al., 1997). As

a result, most the freshwater delivered to the Gulf bylarge Papuan rivers travels eastwards, while only a small

proportion flows towards Torres Strait (Woolfe et al.,

1997). This pattern of water circulation and sediment

movement within the region is substantiated by the dis-

tribution of metals in sediments across the Gulf of Papua

and Torres Strait determined in this study.

Acknowledgements

Foong Chun Kok (Petronas) is thanked for supplyingsediment samples for analysis, Glenn Barry (Queensland

Department of Natural Resources and Mines) coordi-

nated metal analysis of the Torres Strait sediment

samples, Stan Wright (Torres Strait Regional Authority)

coordinated sediment sample procurement and Mike

Ridd (James Cook University) is thanked for reviewing

a draft of the manuscript. This study was funded

through Environment Australia.

References

Alongi, D.M., Tirendi, F., Robertson, A.I., 1991. Vertical profiles of

copper in sediments from the Fly River delta and Gulf of Papua

(Papua New Guinea). Marine Pollution Bulletin 22, 253–255.

ANZECC, 2000. Australian and New Zealand guidelines for fresh and

marine water quality. Australian and New Zealand Environment

and Conservation Council.

Apte, S.C., Day, G.M., 1998. Dissolved metal concentrations in the

Torres Strait and Gulf of Papua. Marine Pollution Bulletin 36,

298–304.

Baker, E.K., Harris, P.T., 1991. Copper, lead and zinc distribution in

the sediments of the Fly River delta and Torres Strait. Marine

Pollution Bulletin 22, 614–618.

Baker, E.K., Harris, P.T., Beck, R.W., 1990. Cu and Cd associated

with suspended particulate matter in Torres Strait. Marine Pollu-

tion Bulletin 21, 484–486.

Blakemore, L., Searle, P.L., Daly, B.K., 1987. Methods for the

Analysis of Soils. New Zealand Soil Bureau.

Clarke, K.R., Warwick, R.M., 1994. Change in Marine Communities:

An Approach to Statistical Analysis and Interpretation. Natural

Environmental Research Council, England.

Dight, I.J., Gladstone, W., 1993. Torres Strait baseline study: pilot

study final report June 1993. Great Barrier Reef Marine Park

Authority Research Publication No. 29. Great Barrier Reef Marine

Park Authority, Townsville.

Evans-Illidge, E., 1997. Heavy metals in commercial prawn and

crayfish species of the Torres Strait. Report 5b, Great Barrier Reef

Marine Park Authority Report Series. Great Barrier Reef Marine

Park Authority, Townsville.

Gladstone, W., 1996. Trace metals in sediments, indicator organisms

and traditional seafoods of the Torres Strait. Final report of the

Torres Strait Baseline Study. Great Barrier Reef Marine Park

Authority, Townsville.

NSR, 1997. PNG gas project: draft environmental impact statement

and impact assessment study, main report. Report No. CR 790/9/

v3. NSR Environmental Consultants, Hawthorn East, Australia.

Wilkinson, L., 1996. Systat 7.0 for Windows: Statistics. Microsoft,

Chicago.

Wolanski, E., Spagnol, S., King, B., Ayukai, T., 1999. Patchiness in

the Fly River plume in Torres Strait. Journal of Marine Systems 18,

369–381.

Fig. 2. Cluster dendogram and PCA ordination of sediment heavy

metal concentrations.

1312 Baseline / Marine Pollution Bulletin 44 (2002) 1296–1313

Woolfe, K.J., Larcombe, P., Whitmore, G.P., 1997. Marine geology of

the western Gulf of Papua. James Cook University, Townsville.

Table 5

Comparison of Torres Strait sediment heavy metal concentrations with

concentrations detected in past surveys

Element Torres Strait

Alongi

et al.

(1991)

Baker and

Harris

(1991)

Dight and

Gladstone

(1993)

This study

Aluminium 0.20–10.2 0.34–9.68

Iron 900–48,600 1200–57,500

Strontium 179–2634

Cobalt 1–17 <6–21

Chromium 5–103 12–128

Copper 7–71 1–71 2–44 <8–29

Manganese 69–724 109–1363

Nickel 4–52 <10–42

Lead 0–22 0.5–24 <4–34

Zinc 0–111 2–105 <12–113

Cadmium 0.01)0.21 0.02)0.11Mercury <0.05)0.12 <0.01)0.07Arsenic 1–36 3–32.3

Al %, all other data mgkg�1 dry weight.

Table 6

Summary of ANOVAs of Torres Strait sediment metal concentrations

Parameter ANOVA F ratio Summary of Tukey mul-

tiple-comparison testing

Calcium carbonate 52.848� Gulf NTS STS CTS

Aluminium 55.225� CTC STS NTS Gulf

Arsenic 2.477

Cadmiuma 2.201

Chromiuma 27.010� STS CTS NTS Gulf

Cobalt 58.383� STS CTS NTS Gulf

Coppera 246.486� Torres Straitb Gulf

Irona 9.778� STS CTS NTS Gulf

Leada 19.576� CTS STS NTS Gulf

Manganesea 46.075� STS CTS NTS Gulf

Mercurya 27.434� STS CTS NTS Gulf

Nickela 93.3311� CTS STS NTS Gulf

Silicaa 14.294� STS CTS NTS Gulf

Strontiuma 22.050� Gulf NTS CTS STS

Zinca 59.709� STS CTS NTS Gulf

Regions joined by a horizontal line are not significantly different.

Gulf ¼ Gulf of Papua, NTS ¼ northern Torres Strait, CTS ¼ centralTorres Strait, STS ¼ southern Torres Strait.* p < 0:0001.aData log10 transformed prior to analysis.bAll copper values were less than the detection limits (<8 mgkg�1)

for sediments collected away from the Gulf.

Fig. 3. Clustering of sediment sampling sites based on multivariate analysis of sediment metal concentrations.

0025-326X/02/$ - see front matter � 2002 Elsevier Science Ltd. All rights reserved.

PII: S0025-326X(02 )00229-1

Baseline / Marine Pollution Bulletin 44 (2002) 1296–1313 1313