hg in buyat
TRANSCRIPT
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Heavy metal contamination from gold mining recorded in Porites lobata skeletons,
Buyat-Ratototok district, North Sulawesi, Indonesia
Evan N. Edinger a,b,c,*, Karem Azmy c, Wilfredo Diegor c, P. Raja Siregar d
a Department of Geography, Memorial University, St. Johns, NL, Canada A1B 3X9b Department of Biology, Memorial University, St. Johns, NL, Canada A1B 3X9c Department of Earth Sciences, Memorial University, St. Johns, NL, Canada A1B 3X9d Indonesian Forum for the Environment (WALHI), Jl. Tegal Parang Utara No. 14, Jakarta 12790, Indonesia
a r t i c l e i n f o
Keywords:
Submarine mine tailings
Arsenic
Laser ablation ICP-MS
Coral skeleton
Porites lobata
Indonesia
a b s t r a c t
Shallow marine sediments and fringing coral reefs of the Buyat-Ratototok district of North Sulawesi,
Indonesia, are affected by submarine disposal of tailings from industrial gold mining and by small-scale
gold mining using mercury amalgamation. Between-site variation in heavy metal concentrations in shal-
lowmarine sediments was partially reflected by trace elementconcentrations in reef coral skeletons from
adjacent reefs. Corals skeletons recorded silicon, manganese, iron, copper, chromium, cobalt, antimony,
thallium, and lead in different concentrations according to proximity to sources, but arsenic concentra-
tions in corals were not significantly different among sites. Temporal analysis found that peak concentra-
tions of arsenic and chromium generally coincided with peak concentrations of silica and/or copper,
suggesting that most trace elements in the coral skeleton were incorporated into detrital siliciclastic sed-
iments, rather than impurities within skeletal aragonite.
2008 Elsevier Ltd. All rights reserved.
1. Introduction
Retroactive determination of heavy metal concentrations prior
to anthropogenic activities is often crucial to understanding the
environmental impacts of those activities, particularly in locations
where these activities have had a long history. Such retroactive
determination is particularly difficult in coastal marine environ-
ments, where bioturbation can obscure the temporal record of met-
als in sediments. Coral skeletons have been used extensively to
record the history of metal pollution from dredging, mining, terres-
trial runoff, and other sources on coral reefs (Brown and Holley,
1982; Howard and Brown, 1984, 1987; Anderegg et al., 1997; Scott
and Davies, 1997; Esslemont, 1999, 2000; Fallon et al., 2002; David,
2003; Runnalls and Coleman, 2003). The ability of corals to record
metal pollution varies among metals, due to differences in solubil-
ity and differences in the degree to which trace elements can be
incorporated into aragonite crystal lattice (Howard and Brown,
1984). Arsenic and mercury, two of the principal contaminants
from gold mining, present analytical challenges in this context.
The atomic radius of arsenic is incompatible with the dimensions
of the aragonite crystal lattice, therefore arsenic incorporated into
coral skeletons is thought to be primarily detrital, having entered
the coral skeletonas incorporated siliciclastic sediment, rather than
as dissolved metal. Mercury presents analytical challenges due to
its volatility, which requires distinct analytical techniques for
mercury in sediments from techniques used for most other metals.
Traditionally, studies of trace elements in coral skeletons have
relied upon mechanical sampling followed by chemical analysis
using atomic absorbtion spectroscopy (AAS, e.g. Khaled et al.,
2003), inductively coupled plasma atomic emission spectroscopy
(ICP-AES or ICP-OES, optical emission spectroscopy e.g. Bastidas
and Garcia, 1997; David, 2003), or solution inductively-coupled
plasma-mass spectrometry (ICP-MS, e.g. Scott and Davies, 1997).
Of these methods, ICP-MS is the most sensitive, and has the great
advantage of analyzing a wide suite of elements simultaneously
(Scott and Davies, 1997).
Several recent research efforts relating to coral skeletal records
of pollution have used laser ablation mass-spectrometry (LAM-
ICPMS) to reconstruct the history of trace element pollution from
coral skeletons (Fallon et al., 2002; Runnalls and Coleman, 2003).
Laser ablation has several advantages over traditional analytical
methods, including ability to extract precisely located samples
from within the coral skeleton, ability to measure concentrations
of a wide range of elements simultaneously, and direct introduc-
tion of sample to the analytical instrument, thus skipping exten-
sive cleaning, dissolution and possibilities of contamination or
operator error associated with wet chemistry (Veinott, 2001).
Laser ablation may also introduce some challenges, however.
Laser ablation ICP-MS may induce fractionation of some isotopes
as the ablation pit becomes deep (Eggins et al., 1998; Gunther
0025-326X/$ - see front matter 2008 Elsevier Ltd. All rights reserved.doi:10.1016/j.marpolbul.2008.05.028
* Corresponding author. Address: Department of Geography, Memorial Univer-
sity, St. Johns, Canada NL A1B 3X9. Tel.: +1 709 737 3233; fax: +1 709 737 3119.
E-mail address: [email protected] (E.N. Edinger).
Marine Pollution Bulletin 56 (2008) 15531569
Contents lists available at ScienceDirect
Marine Pollution Bulletin
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / m a r p o l b u l
mailto:[email protected]://www.sciencedirect.com/science/journal/0025326Xhttp://www.elsevier.com/locate/marpolbulhttp://www.elsevier.com/locate/marpolbulhttp://www.sciencedirect.com/science/journal/0025326Xmailto:[email protected] -
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and Hattendorf, 2001), and laser ablation necessarily mixes lattice-
bound trace elements incorporated from solution with those in-
cluded within the skeleton as detrital sediment (e.g. Runnalls and
Coleman, 2003). Finally, for metals that are heterogeneously dis-
tributed within the skeleton, the high spatial precision of off-the-
shelf laser ablation IPC-MS systems may contribute to high inter-
sample variation that obscures broader patterns.
The objectives of this paper are (1) to compare spatial patterns
of trace element concentration in marine sediments with those in
coral skeletons, and (2) to examine temporal patterns in trace ele-
ment concentrations in coral skeletons as a historical record of
contamination from gold mining activities. We present trace ele-
ment concentrations and chronologies from Porites lobata corals
collected on reefs adjacent to two distinct types of gold mining
activities: submarine tailings disposal of industrial gold mine tail-
ings, and small-scale gold mining using mercury amalgamation in
coastal watersheds. Our results show that coral skeletons can re-
cord trace element contamination from distinct types of gold min-
ing activities, including trace elements that are normally not
incorporated into aragonite coral skeletons. In addition, we address
two methodological points, (1) comparing whole-sediment and
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mental danger on the basis of the low dissolved metal concentra-
tions (PTNMR, 2002b), but elevated arsenic and antimony concen-
trations in shallow marine sediments suggest tailings dispersal at
least 1 km northeast, and at least 3 km southeast, of the tailings
outfall, in waters as shallow as 20 m (Edinger et al., 2007). Arsenic
in tailings includes both geochemically stable and reactive forms,
but antimony in tailings is mostly stable (Blackwood and Edinger,
2007).
1.1.2. Small-scale mining
Small-scale mining in Indonesia releases large fluxes of mercury
to air and water, contributing mercury to fish consumed by hu-
mans (Kambey et al., 2001; Limbong et al., 2003). In the region
of this study, artisanal gold miners operated extensively in the To-
tok and Kotabunan watersheds (Fig. 1) until approximately 1989,
although artisanal gold mining continues to a much lesser extent
in both areas. No small-scale mining has occurred in the Buyat Riv-
er watershed. Concentration of arsenic, cobalt, copper, and other
metals in sediments affected by artisanal mining was slightly high-
er than in regional pre-mining background analyses, possibly due
to enhanced erosion associated with mining activities (Edinger
et al., 2007).
2. Materials and methods
2.1. Sampling areas
Field sampling took place on fringing reefs of Buyat and Totok
Bays (Fig. 1). Buyat Bay (approximately 050.40N/12442.30E) is a
small bay exposed to wave action from the Molucca Sea. The Buyat
River debouches at the NW corner of the bay, and a coarse sand
tombolo separates Buyat Bay from Totok Bay. The east side of Buy-
at Bay hosts fringing coral reefs; the reefs closest to the beach are
now completely dead, while those monitored by the mining com-
pany, in the outer portion of the bay and along the outer margin of
the Ratototok Peninsula are in better condition (PTNMR, 2002b).
Maximum depth in the bay is approximately 90 m. The shelf re-
mains relatively flat until reaching the shelf break at about
120 m depth, roughly 8 km from shore, from which point the bot-
tom descends to bathyal depths (PTNMR, 1994). The shape of the
Buyat River mouth, visible plumes of sediment from the Buyat Riv-
er, and PTNMR current meter data suggest that surface currents
generally flow counter-clockwise around the bay. Bottom currents
appear to follow a similar pattern (PTNMR, 1994, 2002a, b).
Totok Bay (approximately 0520N/12442.70E) is a larger bay
protected from wave action by the Ratototok Peninsula. Coastlines
are mangroves along the protected side of the tombolo separating
Totok Bay from Buyat Bay and along the northern margins of the
bay, fringing coral reefs along the inner side of the Ratototok Pen-
insula and the islands in the bay, and cleared mangrove in front of
Ratototok village, and adjacent to the mouth of the Totok River.Maximum depth is about 100 m. The shape of sand spits suggests
that currents in Totok Bay generally flow in a counter-clockwise
direction around the bay.
The climate is monsoonal, with a rainy season November to
April, and dry season May to October. Sea surface temperatures
range from 27 to30 C (PTNMR, 1994). Tides in the region are mixed
semi-diurnal and microtidal, with a spring tide range of approxi-
mately 1.2 m.
2.2. Sediment sample collection and analysis
Reef sediments and coral skeletons were collected in June 2002
(17 sediment samples, BY01-18), with further sediment samplingin August 2004 (25 sediment samples, BY21-52). Sediment analysis
characterized end-members of sediment in the system, including
three primary sources: artisanal gold mining (the Totok River
and Kotabunan River) industrial gold mine tailings disposed in
Buyat Bay, and the Buyat river, which drains the mine site and
has similar bedrock geology to the Totok River watershed (Edinger
et al., 2007). Background sediment composition was determined
from two sources: the sites furthest to sea in Totok Bay (BY15,
BY45 and BY51), and the description of marine sediments collected
in 1993 for the industrial gold mines Environmental Impact
Assessment (PTNMR, 1994).
Sediment samples were collected using a hand-operated Petit-
Ponar grab sampler deployed from a motorized outrigger canoe
or fishing boat. Position of sampling station positions were re-corded using a hand-held GPS. Depth was determined by the
length of grab sampler rope; depth measurements associated with
grab samples are therefore maximum depth estimates. Visual
descriptions of sediment colour, grain size, and bulk composition
(carbonate vs. siliciclastic) were recorded in the field, with subse-
quent measurement of grain size distribution and carbonate con-
tent in the lab. All samples were frozen immediately upon return
to shore and kept frozen until analysis.
2.3. Sediment trace element analysis
Three gram sediment subsamples were dry-sieved through a
0.063 mm polyurethane mesh to account for grain-size related
biases in sediment chemistry. Sediment subsamples were homog-enized by stirring, dried, ground to
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where 0.40 is the weight percent Ca in CaCO3. Although this method
could overestimate the carbonate content of sediments by including
Ca from volcanic rocks, the weight percent of Ca in calcium carbon-
ate is more than three times that of the weight percent Ca of calcic
plagioclase, such that nearly all Ca was probably present as CaCO 3.
Pre-mining sediment chemistry is reported as the average of 31
marine sediment samples from Buyat Bay and environs, as reported
in the mining companys original environmental impact assessment
(PTNMR, 1994).
Fig. 2. X-ray negative of coral skeleton BY04L, showing density bands. Approximate
track of carbonate sampling and laser ablation analysis indicated by dashed black
line. White scale bar 1 cm.
Table 2
Sediment (
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2.5. Coral skeleton sample collection and analysis
Domal P. lobata corals were collected whole from approxi-
mately 1 m below low tide on seven fringing reefs surrounding
Buyat Bay and Totok Bay. Sites BY04, BY05, BY07, BY08, and
BY10 were all from fringing reefs surrounding Buyat Bay. Site
BY14 is a small fringing reef near the mouth of the Totok River. Site
BY15 is a fringing reef on the southwest corner of Pulau Babi, in To-
tok Bay, approximately 3 km from the Totok River, and serves as a
reference site for the Totok River. Coral skeletons were cut in half
vertically and air dried in the field prior to shipment to Canada,
where all further analysis took place.
Coral skeletons were cut into 810 mm thick slabs parallel to
growth lines using a diamond blade rock saw cooled with tap
water. Coral skeleton slabs were rinsed with distilled water after
cutting, and etched in 0.2 N HNO3 prior to analysis. Each coral skel-
eton slab was X-rayed to reveal density bands (Fig. 2). For each cor-
al, the slab showing the clearest banding, and for which the cut
was most clearly parallel to corallites, was selected for further
analysis. Analyses did not follow the axial growth direction of
the coral, hence distance between growth bands does not directly
reflect coral skeletal extension rates (Edinger et al., 2000).
2.6. Coral skeleton stable isotope sampling and analysis
To verify that density bands in coral skeletons were annual
growth bands, and to assure time control within coral skeletons,
d13C and d18O of coral skeleton aragonite were analyzed in coral
BY04, and Sr/Ca ratios of coral skeletal aragonite were analyzed
in all samples (see below). Small subsamples of skeleton, approx-
imately 320 lg, were drilled from the skeletons along lines per-
pendicular to growth banding at 2 mm increments. Samples
were reacted in inert atmosphere with ultrapure concentrated
orthophosphoric acid at 72 C in a Thermo-Finnigan Gasbench
II; the produced CO2 was automatically delivered to a Thermo-
Finnigan Delta-plus XP isotope ratio mass spectrometer in a
stream of helium and measured for isotope ratios. Laboratory
standards NBS-18 and NBS-19 were repeatedly measured during
each analysis run and yielded a routine precision better than 0.1
per mille.
2.7. Coral skeleton trace element concentrations
Coral skeleton trace element concentrations were analyzed
using laser ablation-ICPMS. Coral skeleton slabs were cut to
46 23 6 mm (standard thin-section size) blocks for insertion
into the laser ablation sample cell. Distance down the coral skele-
ton was recorded to the nearest 10 lm using the position of the
sampling carriage. A NuWave UP 213 nm NdYAG laser system
was interfaced to an HP 4500 quadrupole ICPMS with argon as
the plasma gas, and helium as the carrier gas. The laser was set
to 80 um spot size at 10 Hz, yielding an average beam intensity
of 0.5 mJ, equivalent to 11 J/cm2. In all analyses, 44Ca was used as
the internal standard. Analyses were conducted on three days:
November 14, 2005, November 17, 2005, and August 31, 2006.
Each run of 20 analyses included four analyses of NBS 610 glass
standard, three analyses of MACS-1 coral aragonite reference
material, and at least one duplicate analysis of coral skeleton from
the same vertical position within the coral skeleton. In coral BY04,
laser ablation spots were matched to the position of the drill holes
for carbonate d13C and d18O analyses. Because of the open skeletal
nature of P. lobata, analyses did not strictly follow corallite walls.
Duplicate analyses were run to check for consistency, and in cases
where the initial run displayed significant yield attenuation.
Fig. 4. Trace element concentrations in sediments (
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Trace element concentrations in coral skeletons were calibrated
to the NBS 610 fused glass standard, rather than the MACS-1 car-
bonate reference material, because there are, as yet, no published
certified values for MACS-1. Instead, the MACS standard was used
for quality control. The relative standard deviation (RSD) and stan-
dard error (sd/n1/2) of each element measured was calculated for
the MACS standard, as a measure of the consistency with which
the laser-ablated carbonates released each element to the mass
spectrometer. The results from the LA-ICPMS analyses of the MACS
standard were compared to data obtained by solution ICPMS done
in the same lab, using the procedure described for sediment trace
element analysis.
2.8. Data analysis
Prior to statistical analysis, repeat coral skeleton trace element
concentration data were screened to assess variability and to con-
solidate repeat analyses. Repeat analyses for which the initial abla-
tion signal displayed significant attenuation were removed.
Second, the average of repeat analyses was calculated for pairs that
both had consistent yield. Because concentrations of trace ele-
ments in coral skeletons appeared non-normal, concentrations
were compared among sites using exploratory data analysis(EDA) and the KruskallWallis test. Correlation coefficients among
the elements analyzed in all coral skeleton ablations were calcu-
lated using bivariate linear correlation of log-transformed concen-
trations. Correspondence between metal concentrations in the
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including the tailings, and 1570% in reef sediments (Table 2). Car-
bonates in reef sediments were easily recognizable as poorly-
sorted, angular, very coarse-grained bioclasts from corals, calcare-
ous algae and molluscs, while carbonates in fluvial and non-reefal
sediments were mostly subangular crystalline detrital carbonates
(Fig. 3).
Most sediment samples were >70% siliciclastic, except BY05,
BY07, BY08, BY10, BY15, BY29, and BY51 (Fig. 3; see Appendix 1).
Of the siliciclastic samples, most were dominantly siliciclastic
mud, except for shallow nearshore samples BY07, BY09, BY11,
BY39, BY41, and BY52, collected near the mouths of the Buyat, To-
tok, and Kotabunan rivers, and samples BY16, 17, and 18, collected
in the Buyat and Totok rivers (Table 2, Appendix 1). The samples
collected near the end of the tailings pipe were fine silts.
3.2. Sediment trace element concentrations
3.2.1. Sediment sample analytical accuracy and precision
Duplicate analyses of identical samples for sediment metal con-
centrations (n = 4 pairs) yielded results differing by
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fractions of sediments from the two Totok Bay reefs, while anti-
mony concentrations in Totok Bay reef sediments were 12 times
elevated in the mud fraction over whole sediment values.
3.3. Coral skeletal metal analyses
3.3.1. Laser ablation and solution ICP-MS analysis of MACS-1 reference
materialAmong the oxides and elements considered here, MgO, Al2O3,
Ti, V, As, Sb, and Tl had RSD values greater than 50%, while SiO2,
FeO, Cr, Mn, Co, Ni, Cu, Zn, Ba, and Pb had RSD values less than
40% (Table 5). RSD for Sr ranged from 12% to 20%, with the highest
value observed in 84Sr, and the lowest in 86Sr.
Laser ablation analyses of MACS-1 for SiO2, Ti, V, Mn, As, and Tl
differed from solution analyses by 100% or more, while analyses for
FeO, Cr, Co, Ni, Cu, Zn, Sb, Ba, and Pb differed from the solution
analysis by less than 50%.
3.3.2. Variation in coral skeleton trace element concentrations amongreefs
Median aluminum oxide concentrations were lowest in corals
from exposed, siliciclastic poor sites BY08 and BY10 (Fig. 5A,
0.05
0.04
0.03
0.02
0.01
0.00
BY05-11
BY05-20
BY04L-31
BY10-17
BY15-22
BY08-40r
BY14-1
BY14-5
BY07-16BY05-19r BY14-21
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
BY10-01
BY05-13
BY10-03
BY15-13
BY08-8r
0.50
0.40
0.30
0.20
0.10
0.00
BY10-17BY08-13
BY14-1
BY14-3BY07-7
By05-1
BY04L-4
BY10-10BY08-12
BY08-15
BY07-5
0.12
0.10
0.08
0.06
0.04
0.02
0.00
BY04L-42
BY04L-38
BY14-1
BY07-5
By05-1
BY04L-33
BY10-01BY15-19r
BY08-7
BY07-3
BY04 BY 07 BY 08 BY 10 BY 14 BY 15BY 05
BY04 BY 07 BY 08 BY 10 BY 14 BY 15BY 05 BY04 BY 07 BY 08 BY 10 BY 14 BY 15BY 05
BY04 BY 07 BY 08 BY 10 BY 14 BY 15BY 05
A
lO
wt%
2
3
S
iO
wt%
2
MgO
wt%
FeO
wt%
A B
DC
Fig. 5. Boxplots showing major oxide concentrations in coral skeleton analyses. (A) Aluminum oxide, (B) silica, (C) magnesium oxide and (D) iron oxide concentrations in
coral skeletons.
Table 6
KruskallWallis tests comparing trace element concentrations in coral skeletons
Element or oxide Sediment group Rank order among corals Significance
Al2O3 Oxides, fluvial BY05 > BY04 = BY05 = BY14 = BY15 > BY08 > BY10 P< 0.001
SiO2 Oxides, fluvial BY14 > BY05 = BY04 > BY08 = BY10 > BY15 > BY07 P< 0.001
FeO Oxides, Fluvial BY05 > BY15 > BY08 = BY10 > BY14 > BY04 > BY07 P< 0.001
Cr Fluvial or tailings BY04 > BY07 = BY14 > BY05 = BY08 = BY10 > BY15 P< 0.001
Co Fluvial BY04 = BY08 > BY15 > BY05 > By07 = BY10 > BY14 P< 0.001
Cu Fluvial BY04 > BY15 > BY07 = BY10 > BY05 = BY08 = BY14 P< 0.001
Pb Fluvialartisanal BY05 > BY04 = BY08 > BY07 = BY10 > BY14 = BY15 P< 0.001
As Tailings BY04 = BY14 > BY05 = BY07 = BY08 = BY10 = BY15 P= 0.178
Sb Tailings BY04 > BY14 = BY05 = BY08 > BY07 > BY10 = BY15 P< 0.001
Tl Tailings BY04 > BY05 > BY08 = BY14 > BY10 = BY15 > BY07 P< 0.001
Sites: Reef closest to tailings: BY04, Tj. Buyat reef: BY05, Tj. Sikod: BY08, Ratototok Peninsula: BY10, Bobokan Reef (Buyat river mouth): BY07, Totok river mouth: BY14,Reference: BY15. Significance indicated by KruskallWallis test.
1560 E.N. Edinger et al. / Marine Pollution Bulletin 56 (2008) 15531569
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Peak concentrations of arsenic and antimony in Tj. Buyat coral
BY10 were recorded in 2000, and coincided with a minor peak in
Cr, and with mildly elevated concentrations of SiO2, Cu, and Ba
(Fig. 8C). Smaller peaks in Sb and Cr co-occurred, and coincided
with Cu orSiO2 peaks, but not with peaks in Ba concentration. Peak
concentrations of As in Tj. Sikod coral BY08 occurred in 1996, 1997,
and 1999, with a minor peak in late 1998 (Fig. 8D). Peak concentra-
tions of As and Cr frequently co-occurred, but peaks in As and Sb
did not. Peak concentrations of As generally coincided with peaksin silica content.
Concentrations of As and Sb in Bobokan coral BY07 (near the
Buyat river mouth) were generally low, often close to the detection
limit for these elements (Fig. 9A). Peak concentrations of Cr in coral
BY07 occurred in 1998, 1999, and 2001, and generally coincided
with peaks in Ba, SiO2, and Cu. Peak concentrations of As and Sb
in coral BY14 (Totok River mouth) occurred in 1998, 1999, and
2001, with additional high concentrations recorded in the two
ablations closest to the upper surface of the coral (Fig. 9B). These
high concentrations probably resulted from remnant tissue con-
tamination of the material ablated. Peak concentrations of Sb and
Cu generally coincided with peak concentrations of SiO2, or to a
lesser extent, Cu, but had little apparent relationship with Ba con-
centrations, except for the elevated As and Sb concentrations in
2001. Concentrations of antimony in reference coral BY15 were
generally below detection limits (Fig. 9C). Arsenic concentrations
had low peaks in 1998, 2000, and near the top of the coral, but
these peaks did not have a clear correspondence with Ba, Cu, or
SiO2. Chromium peaks in BY15 were generally associated with
minor peaks in silica content. Two major peaks in Cu in 1999
2000 also coincided with increases in silica content.
3.4. Correlations between trace elements in sediments and in coral
skeletons
Trace element concentrations in sediments (
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Table 7
Correlation matrix among elements recorded in coral skeletons, ln-transformed
MgO Al2O3 SiO2 CaO42 CaO43 FeO Co Cu Zn As Sb Ba Tl
Al2O3 0.060
SiO2 0.063 0.507**
CaO_42 0.040 0.002 0.038
CaO_43 0.016 0.002 0.165* 0.534**
FeO 0.077 0.646** 0.329** 0.006 0.168*
Co 0.117 0.069 0.022 0.002 0.037 0.09Cu 0.068 0.005 0.061 0.041 0.073 0.066 0.19**
Zn 0.008 0.11 0.258** 0.026 0.065 0.079 0.099 0.305**
As 0.034 0.294** 0.247** 0.143* 0.151* 0.215** 0.029 0.000 0.142*
Sb 0.016 0.006 0.252** 0.047 0.013 0.132 0.027 0.046 0.159* 0.226**
Ba 0.383** 0.128 0.141* 0.144* 0.087 0.308** 0.052 0.127 0.088 0.012 0.024
Tl 0.32 0.155* 0.261** 0.007 0.059 0.07 0.024 0.109 0.211** 0.204** 0.280** 0.052
Pb 0.133 0.047 0.141* 0.022 0.014 0.171* 0.034 0.234** 0.115 0.112 0.075 0.251** 0.067
** p < 0.01, * p < 0.05. N= 207 in all cases.
0
8
4
12
16
20
[Ba,
Cu
],ppm,
[Si/100]ppm
Ba
Cu
SiO /100
100 20 30 40 50 60 70 80 90 100
vertical distance (mm)
200
2
200
1
200
0
199
9
199
8
199
7
199
6
BY 04 (closest reef to tailings outfall)
18O
O
7.0
7.5
8.0
8.5
9.0
Sr/
Cammo
l/mo
l
9.5
As
Sb
Cr
0.0
0.4
1.6
0.8
1.2
2.0
[As,
Sb
,Cr]
Sr/Ca
-4.5
-5.0
-5.5
-6.0
-6.5
Fig. 8. Coral skeleton trace element chronologies: reef affected by industrial mine tailings. (A) Reef inside Buyat Bay (BY04). (B) Tj. Buyat (BY05). (C) Ratototok Peninsula(BY10); (D) Tj. Sikod (BY08). Annual bands (vertical grey bars) were identified using the skeletal density bands, and verified as annual using Sr/Ca ratios.
E.N. Edinger et al. / Marine Pollution Bulletin 56 (2008) 15531569 1563
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elling with fine-grained silica from mine tailings, rather than pyritecrystalswith arsenicor antimony-rich rims (Blackwood and Edinger,
2007). Amorphous colloidal ironarsenic phases were observed intailings sediment and in sediments from Buyat Bay reef BY04 and
2002
2001
2000
1999
1998
7.0
7.5
8.0
8.5
9.0
Sr/Cammo
l/mol
9.5
5 10 15 20 25 30 35 40 45 50
0
8
4
12
16
20
[Ba,
Cu],ppm,
[Si/100]ppm
SiO /10
BaCu
vertical distance (mm)
BY 05 (500 m east of tailings outfall)
0.0
0.4
1.6
0.8
1.2
2.0
[As,
Sb
,Cr,]
As
Cr
Sb
7.0
7.5
8.0
8.5
9.0
Sr/
Cammo
l/mo
l
9.5
50 10 15 20 25 30 35 40 45
2002
2001
2000
1999
1998
vertical distance (mm)
BY 10 (1 km east of tailings outfall)
Sb
Cr
As
0.6
0.0
0.4
0.2
0.8
1.0
[As,
Sb
,Cr,
]
Cu
Si/100
Ba
0
8
4
12
16
20
[Ba,
Cu
],ppm,
[Si/100]ppm
Fig. 8 (continued)
1564 E.N. Edinger et al. / Marine Pollution Bulletin 56 (2008) 15531569
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Tj. Buyat Reef BY05 (Blackwood and Edinger, 2007). However, ironand arsenic peaks did not always coincide in skeletal chronologies,
and iron and arsenic were not correlated in coral skeletal analyses
from siteBY04,suggesting thatmuchof thearsenicin coral skeletons
may have been present as Mgarsenate, another tailings processing
by-product. Arsenic in Totok Bay reefs was likely present as fine-
grained arsenopyrite (Blackwood and Edinger, 2007); silt-sized
grains of arsenopyrite were observedin sediment from both the To-
tok and Buyat rivers (Blackwood and Edinger, 2007).
4.2. Influence of grain size on sediment trace element analyses
Sediment trace element analysis results for the mud fraction
were highly consistent with whole sediment concentrations previ-
ously reported for the same sites (Edinger et al., 2007; Table 4). Themajor differences encountered were at tailings-influenced sites
dominated by bioclastic reef sediment, particularly BY05, BY08,
and BY10 (Edinger et al., 2007). The fine fraction sediment data fur-
ther document dispersal of mine-tailings derived sediment onto
reefs 12 km away from the mine tailings outfall (Edinger et al.,
2007). The high degree of agreement between whole-sediment
and
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7/29/2019 Hg in Buyat
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various trace elements rather than a fused homogenized glass,inhomogeneities can be expected, particularly for elements incom-
patible with the aragonite crystal lattice. Similarly, differences inablation yield between the fused glass standard, the MACS
50 10 15 20 25 30 35 40 45
0
8
4
12
16
20
[Ba,
Cu],ppm,
[Si/100]ppm
Ba
Cu
SiO /100
vertical distance (mm)
2002
2001
2000
1999
BY 07 (closest to Buyat river mouth)
1998
As
Cr
Sb0.0
0.4
1.6
0.8
1.2
2.0
[As,
Sb,
Cr,]
7.5
8.0
8.5
9.0
Sr/C
ammol/mol
9.5
50 10 15 20 25 30 35 40 45
vertical distance (mm)
2002
2001
2000
1999
BY 14 (closest to Totok river mouth)
1998
0
8
4
12
16
20
[Ba,
Cu
],ppm,
[Si/100]ppm
Ba
Cu
SiO /100
As
Cr
Sb
0.0
0.4
1.6
0.8
1.2
2.0
[As,
Sb,
Cr,
]
8.0
8.5
9.0
9.5
10.0
Sr/
Cammo
l/mo
l
Fig. 9. Coral skeleton trace element chronologies: reef affected by fluvial runoff, artisanal mining, and reference site. (A) Bobokan, near Buyat river mouth (BY07); (B) Totok
River mouth (BY14), affected by artisanal mining; (C) Reference site, Pulau Babi, Totok Bay(BY15). Annual bands (vertical grey bars) were identified using theskeletal density
bands, and verified as annual using Sr/Ca ratios.
1566 E.N. Edinger et al. / Marine Pollution Bulletin 56 (2008) 15531569
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pressed-pellet carbonate reference material and the porous arago-
nitic coral skeletons may also contribute to analytical uncertainty.
Lateral variation in detrital material incorporation at a scale of
1001000 lm likely accounted for the high variability in most me-
tal chronologies, and the relatively low repeatability of laser abla-
tion analyses in the coral skeleton samples. Some laser ablation
ICP-MS systems have been modified to sample from a larger area
(50 500lm), rather than a discrete circular ablation pit (e.g. Sin-
clair et al., 1998; Fallon et al., 2002, 2003; Sinclair, 2005 ). Such a
modified laser ablation system could probably avoid some of the
problems with small-scale spatial heterogeneity observed in this
study, as it would average the element concentrations within a
wider area. Similarly, drilling out subsamples of coral skeleton
for solution analysis (cf. Shen and Boyle, 1989; Bastidas and Garcia,
1997; David, 2003) would likely yield a greater amount of total
material, possibly avoiding issues with
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