Available online at www.sciencedirect.com

ARTICLE IN PRESS

www.elsevier.com/locate/marpolbul

Marine Pollution Bulletin 55 (2007) 459–468

Total and labile metals in surface sediments of the tropicalriver-estuary system of Marabasco (Pacific coast of Mexico):

Influence of an iron mine

Ana Judith Marmolejo-Rodrıguez a,b,*, Ricardo Prego b, Alejandro Meyer-Willerer c,Evgueni Shumilin a, Antonio Cobelo-Garcıa b

a Centro Interdisciplinario de Ciencias Marinas, (IPN) La Paz, B.C.S., Mexicob Instituto de Investigaciones Marinas, (CSIC), Vigo, Spain

c Centro Universitario de Investigaciones Oceanologicas, Universidad de Colima, Col., Mexico

Abstract

Marabasco is a tropical river-estuary system comprising the Marabasco river and the Barra de Navidad Lagoon. The river is impactedby the Pena Colorada iron mine, which produces 3.5 million tons of pellets per year. Thirteen surface sediment samples were collected inMay 2005 (dry season) in order to establish background levels of Al, Cd, Co, Cu, Fe, Ni, Pb, and Zn in the system and to ascertain thepotential mobility of metals in the sediments. Analyses were carried out in the fraction finer than 63 lm, and labile metals extractedaccording the BCR procedure. Certified reference materials were used for validation of methods.

Total concentrations of Cd, Co, Cu, Ni, Pb, and Zn were in the range of 0.05–0.34, 6–95, 0.7–31, 9–26, 2–18, and 53–179 mg kg�1,respectively; Al and Fe ranges of 24–127, and 26–69 mg g�1 correspondingly. Cadmium was found to be significantly labile in the sed-iments (20–100%), followed by Co (0–35%), Ni (3–16%) and Zn (0–25%), whereas the labile fraction for Cu, Fe and Pb was almost neg-ligible (<4%).

According with the total metal concentrations, background levels and normalised enrichment factors (NEF) of the metals studied, theimpact of the Pena Colorada iron mine on the Marabasco system is lower than expected when compared with other similar World sys-tems influenced by mining activities.� 2007 Elsevier Ltd. All rights reserved.

Keywords: Metals; Sediments; Labile fraction; Background levels; Iron ore mine; Marabasco; Mexico

1. Introduction

Rivers transport trace metals into the marine environ-ment, and the magnitude of the metal inputs to the oceansdepends on their levels in the river sediments, water, sus-pended particulate matter, and the exchange processes thattake place in the estuaries (Chester, 2003). Total concentra-tion of metals is generally not sufficient to assess their envi-

0025-326X/$ - see front matter � 2007 Elsevier Ltd. All rights reserved.

doi:10.1016/j.marpolbul.2007.09.008

* Corresponding author. Present address: Instituto de InvestigacionesMarinas, (CSIC), Vigo, Spain.

E-mail addresses: amarmole@ipn.mx, anajudithmr@yahoo.com (A.J.Marmolejo-Rodrıguez).

Please cite this article in press as: Marmolejo-Rodrıguez, A.J. et al.Mar. Pollut. Bull. (2007), doi:10.1016/j.marpolbul.2007.09.008

ronmental impact and the estimation of the bioavailablefraction becomes necessary. This bioavailable fraction isthus defined as the amount of metal that can be exchangedwith biological organisms and be incorporated into theirstructure (Vangronsveld and Cunnihgham, 1998). Thisfraction depends on the association of the elements withparticles, the binding strength and the water propertiessuch as pH, and the redox potential, salinity, dissolvedmetal species which are in touch with the solid phase (Fil-gueiras, 2004). Several analytical methodologies based onsequential extraction procedures have been proposed tostudy the metal mobility and bioavailability in sediments(Kerstern and Forstner, 1991; Quevauviller et al., 1997).

, Total and labile metals in surface sediments of the tropical ...,

460 A.J. Marmolejo-Rodrıguez et al. / Marine Pollution Bulletin 55 (2007) 459–468

ARTICLE IN PRESS

Sequential extraction procedures are generally per-formed by leaching the sample with relatively selectivechemical reagents in order to achieve a progressive dissolu-tion of sought mineralogical phases, and the subsequentrelease of metals. Recent sequential extraction schemes,such as the European Union’s BCR (The CommunityBureau of Reference – BCR, currently known as the Stan-dards, Measurements and Testing programme – SM& T)are proposed to harmonise the different existing proce-dures, obtaining three fractions (acid-soluble, reducibleand oxidisable; Quevauviller et al., 1997; Rauret et al.,1999). In the first fraction of this scheme (also known asthe acid-soluble fraction), exchangeable metals and metalsbound to carbonates are obtained. This fraction providesan estimation of the labile metals in sediments, i.e. metalsthat can be potentially released from the sediments tobecome bioavailable and ultimately a threat to the environ-ment (Morillo et al., 2002).

Previous studies on labile metals in coastal areasimpacted by copper mines can be found in the literature(Morillo et al., 2002; Lopez-Gonzalez et al., 2006) but thereis still a lack of information on the fractionation of metals inrivers and estuaries affected by iron ore mines. A typicalexample of the latter is the tropical Marabasco river-estuarysystem (Fig. 1). The Marabasco river originates in the Man-antlan Mountains at 2400 m above sea level and flows intothe Pacific Ocean in a south–southeast direction with anaverage slope of 12%. The river has a length of 123 km, itis perennial and its mean annual discharge is 22 m3 s�1.Peak discharge can increase up to 750 m3 s�1 during thetropical rainy season. The river basin area is 793 km2 andthe Pena Colorada mine (120,000 tons of iron mineral peryear) is situated approximately at 60 km from its mouth.The estuarine area (Barra de Navidad Lagoon) has a sur-face of 7 km2 and is separated from the ocean by a sand bar.

This region belongs to the ferriferous region of theSouthern Sierra Madre and is characterized by the presenceof a volcano-sedimentary sequence of Cretaceous age (120–90 Ma). It is mainly composed by limestone, clayey lime-stone, limonite and conglomerates with intercalation oflayers of volcanic rocks of andesitic composition. The‘‘average grade’’ contains 35% Fe, 2.3% SiO2, 0.45% Sand 0.005% P, and the remaining 62.2% is mainly calciumcarbonate from the bulk rock (Corona-Esquivel et al., inpress). The significant amount of calcium carbonate couldhave, therefore, an important impact on the lability of met-als in the sediments of the system.

Previous studies of metal concentrations in sediments(Willerer et al., 2003), in suspended particulate matter(SPM) (Shumilin et al., 2005), and rare earth elements ofthe Marabasco system (Marmolejo-Rodrıguez et al.,2007) were mainly carried in the rainy season, but no infor-mation on metal mobility in sediments was given. There-fore the aims of this study are: (i) to assess the totalmetal (Al, Cd, Co, Cu, Fe, Ni, Pb, and Zn) concentrations,distribution and background values in the fine fraction(<63 lm) of the surface sediments, collected in a dry season

Please cite this article in press as: Marmolejo-Rodrıguez, A.J. et al.Mar. Pollut. Bull. (2007), doi:10.1016/j.marpolbul.2007.09.008

and (ii) to ascertain the lability and mobility of these metalson the basis of the acetic-acid-soluble phase according tothe BCR sequential extraction scheme.

2. Materials and methods

2.1. Sampling and sample pre-treatment

Thirteen sites from the Marabasco system were sampledusing a clean plastic shovel and sealable clean plastic bagson May 2005 (dry season) in the Marabasco river, or werecollected from a boat in the Barra de Navidad Lagoonusing an Ekman bottom grab sampler (Fig. 1). Aliquotswere stored in polyethylene (PE) bottles, which were previ-ously washed with 10% HNO3 (>24 h), extensively rinsedwith Milli-Q (Millipore) water, and dried at room temper-ature in a laminar flow bench. Samples were sieved, using arotop instrument, to separate the fine sediment (<63 lm)from the coarse fraction; the fine fraction was then storedat room temperature in PE tubes pending digestion andanalysis. Handling and analysis of samples were carriedout in a clean laboratory, according to trace metal cleantechniques, at the Marine Biogeochemistry ResearchGroup in the Instituto de Investigaciones Marinas IIM-CSIC in Vigo, Spain.

2.2. Total metal concentrations

Weighted sediment samples (�50 mg; semimicro-bal-ance model HM-200 with 0.1 mg precision), were micro-wave-digested (MLS-1200 Mega) in Teflon� bombs usinga mixture of 65% HNO3 and 48% HF (ratio 3:1), accordingto the EPA3052 guideline (EPA, 1996) for siliceous-typesediments. Digests were stored in PE tubes at 4 �C untilanalysis. A marine sediment certified reference material(PACS-2) was used to check the accuracy of the analyticalprocedure. The concentrations of Cd, Co, Cu, Ni and Pb inthe digests were determined by electro thermal atomicabsorption spectrometry (ETAAS; Varian SpectrometerAA Zeeman 220) whereas Al, Fe and Zn were determinedusing a flame atomic absorption spectrometer (FAAS; Var-ian Spectrometer 220FS). The results of the analysis ofPACS-2 are shown in Table 1.

2.3. Labile fraction (Acid-soluble phase)

The method proposed by Quevauviller et al. (1997) wasused to obtain the labile fraction. Briefly, 20 mL of 0.11 Macetic-acid was added to �0.5 g of sediment fine fractionand a magnetic shaker (MI Variel ALC) was used to keepthe sediment sample in suspension during extraction (16 hat 22 �C). Two blanks and one certified reference material(BCR 701) with a replicate were included for method vali-dation. Sediments were then removed by means of centrifu-gation (4400 rpm for 20 min at 22–26 �C) and thesupernatants were stored at 4 �C pending analysis. Theconcentrations of metals in the acid-soluble phase were

, Total and labile metals in surface sediments of the tropical ...,

N

19.42º N

104.05º

A

B

D

C

Peña Colorada Iron ore mine

xx

E

104.40º W

10 km NMEXICO

OceanPacific

PacificOcean

Barra de NavidadTown

104.68º W 104.66º

7

1

3

8

5

6

4 2

rivermouth

1 9 . 18º

19.20˚ N

N1 Km

TouristicArea

PacificOcean

19.18˚

Fig. 1. Map of the Marabasco system, composed by the Marabasco River and its estuary (Barra de Navidad Lagoon) showing the sampling sites.

A.J. Marmolejo-Rodrıguez et al. / Marine Pollution Bulletin 55 (2007) 459–468 461

ARTICLE IN PRESS

determined by ETAAS or FAAS. Results of the methodvalidation are presented in Table 1.

3. Results and discussion

3.1. Background levels and normalised enrichment factor

(NEF) of the fine fraction in the Marabasco system

Background levels (BL) were calculated using Al as thenormalising element (Hanson et al., 1993; Rubio et al.,2000; Zhang, 1995).

Please cite this article in press as: Marmolejo-Rodrıguez, A.J. et al.Mar. Pollut. Bull. (2007), doi:10.1016/j.marpolbul.2007.09.008

Normalised enrichment factors (NEFs) were calculatedusing the following expression:

NEF ¼ ½Me�S=½Me�BL;

where [Me]S represents the metal in a given sample and[Me]BL the uncontaminated sample would have for thataluminium concentration in the same sample. [Me]BL wasobtained from the equation (Fig. 2):

½Me�BL ¼ a½Al� þ b

, Total and labile metals in surface sediments of the tropical ...,

Table 1Check of the accuracy of the analytical procedures using certified reference materials PACS-2 (total metal concentrations) and BCR-701 (labile fraction)

Al Cd Co Cu Fe Ni Pb Zn

PACS-2Obtained 68.8 ± 2.9 2.36 ± 0.35 11.3 ± 0.4 319 ± 16 39.6 ± 2.1 49.4 ± 4.7 189 ± 3 370 ± 7Certified 66.1 ± 5.3 2.11 ± 0.15 11.5 ± 0.3 310 ± 12 40.9 ± 0.6 39.5 ± 2.3 183 ± 8 364 ± 23

BCR701Obtained a 6.08 ± 1.71 1.7 ± 0.6 32.2 ± 7.0 0.095 ± 0.02 15.8 ± 4.2 3.02 ± 0.60 211 ± 59Certified – 7.34 ± 0.35 – 49.3 ± 1.7 – 15.4 ± 0.9 3.18 ± 0.21 202 ± 9

Values in mg kg�1 for Cd, Co, Cu, Ni, Pb and Zn, and mg g�1 for Al and Fe.a Not measured.

462 A.J. Marmolejo-Rodrıguez et al. / Marine Pollution Bulletin 55 (2007) 459–468

ARTICLE IN PRESS

The NEF’s interpretation was realized according to theclassification given by Hakanson (1980) and recently usedby Cobelo-Garcıa and Prego (2004).

3.1.1. Cadmium

The range of Cd was 0.047–0.34 mg kg�1. Measure-ments of Cd are lower in Marabasco than in other systemsnear to mines, such as sediments of Tinto and Odiel rivers,Spain (0.3–65 mg kg�1; Morillo et al., 2002) or in the vicin-ity of Hwacheon, Korea (18 mg kg�1; Lee et al., 2005).However, Cd in Marabasco is in the same range as thosereported in the sediments of the Gualaxo do Norte riverin Brazil (Costa et al., 2003), which is also influenced byiron ore mine (Table 2). Moreover, their Cd levels are sim-ilar to those measured in other world systems without influ-ence of ore mines, such as in the tropical Juru Penangestuary in Malaysia (Khalik et al., 1997) and in the UKestuaries such as Teifi (Bryan and Langston, 1992). There-fore in Marabasco may be defined, in general, as a naturalsystem, according to the Cd background level reported forthe Earth’s crust (Rudnick and Gao, 2003, Table 2). How-ever, the background Cd in Marabasco is very low(0.086 ± 0.032, Table 2) and if they are used to evaluatethe contamination in the area, the Marabasco system canbe defined as moderately contaminated (NEF > 2) in itsriver and non-contaminated in its estuary. In consequence,due to the background Cd concentrations, lithological andenvironmental features should be considered to establishthe anthropogenic and natural enrichments. Thus, the con-cept and reality of the geochemical background describedby Reimann and Caritat (2005) is the most appropriateto be applied in Marabasco and Cd presence in sedimentdoes not represent a contamination problem.

3.1.2. Cobalt

Cobalt range is 6.0–94.5 mg kg�1 (Table 2). Peak con-tents are higher than those found in other systems with ironmine effect, such as the Gualaxo river (Minas Gerais, Bra-zil; Costa et al., 2003) or the tropical Mandovi estuary(India; Alagarsamy, 2006). Nevertheless, in other systemswhich do not have ore mines, the sum of anthropogenicdischarges, may present higher quantities of metals suchas in Saricay stream basin (Turkey) where concentrationswere found up to 476 mg kg�1 of Co (Tuna et al., 2007).

Please cite this article in press as: Marmolejo-Rodrıguez, A.J. et al.Mar. Pollut. Bull. (2007), doi:10.1016/j.marpolbul.2007.09.008

The Marabasco system has local areas of Co accumulation(in the river NEF’s = 9.8; Table 2). However in previousstudies the NEF’s show greater enrichment of this element.

3.1.3. Copper

Highest Cu (range 19.3–96.2 mg kg�1) concentrationswere found in three points located in the centre of the estu-ary (st. 3, 4 and 5 with 81.9, 72.2 and 56.9 mg kg�1, respec-tively) but when these were normalised with Al did notshow enrichment. However, previous studies (Shumilinet al., 2005; Marmolejo-Rodrıguez et al., unpublished data)showed enrichment of Cu in some sampling sites from theMarabasco system. In the river sampling sites the enrich-ment could be attributed to both natural (by the asso-ciation with iron ore) and anthropogenic influence byanti-fouling boat paints in the dock of the town and tour-istic area. Other systems influenced by mines, such as theMandovi estuary in India studied by Alagarsamy (2006)show similar concentration of Cu (range 11.5–77.5 mgkg�1) and anomalies (267 mg kg�1) were found in theGualaxo river (Brazil; Costa et al., 2003). Copper NEF’sand other comparisons can be seen in Table 2.

3.1.4. Iron

River sediments did not show a significant Fe enrich-ment (range 25.7–69.7 mg g�1; Table 2), even in the miningarea. Concentrations are relatively lower than other sys-tems influenced by iron ore mines (e.g. sediments of theGualaxo river, with concentrations above 100 mg g�1 andof the Mandovi estuary 22–497 mg g�1; Table 2). In theMarabasco system Fe was found in considerably higherconcentrations during river floods by Willerer et al.(2003) in the <2000 lm fraction (155–168 mg g�1) and byShumilin et al. (2005) in the SPM (45–87 mg g�1).

3.1.5. Nickel

Nickel was in the range of 8.5–26.1 mg kg�1. It is rela-tively low compared with previous studies (Marmolejo-Rodrıguez et al., unpublished data) in the coarse fraction.In this study, Ni contents are in the range of other worldestuarine areas such as Kranji estuary (Singapore; Cuongan Obbard, 2002) and the Teifi estuary (UK; Bryan andLangston, 1992) without metallic ore influence. In theGualaxo river sediments, punctual Ni contents were

, Total and labile metals in surface sediments of the tropical ...,

Co = 0.156 [Al] + 0.051r2 = 0.70

Al mg g-10 20 40 60 80 100 120 140

Co,

mg

kg-1

0

20

40

60

80

100

Cu = 0.622 [Al] - 0.29r2 = 0.44

Al mg g-1

0 20 40 60 80 100 120 140

Cu,

mg

kg-1

0

30

60

90

120Fe = 0.525 [Al] + 3.87

r2 = 0.97

Al mg g-1

0 20 40 60 80 100 120 140

Fe,

mg

g-1

0

20

40

60

80

100

Ni = 0.165 [Al] + 1.88r2 = 0.68

Al mg g-1

0 20 40 60 80 100 120 140

Ni,

mg

kg-1

0

5

10

15

20

25

30

35

Pb = 0.143 [Al] - 0.99

r2 = 0.82

Al mg g-10 20 40 60 80 100 120 140

Pb,

mg

kg-1

0

5

10

15

20

25

Zn = 1.116 [Al] + 14.72r2 = 0.75

Al mg g-1

0 20 40 60 80 100 120 140

Zn,

mg

kg-

1

0

50

100

150

200

250

Cd = 0.002 [Al] - 0.048r2 = 0.73

Al mg g-1

0 20 40 60 80 100 120 140

Cd,

mg

kg-1

0.0

0.1

0.2

0.3

0.4

Fig. 2. Regression lines of the metal concentrations vs. Al used to calculate the background levels; dashed lines represent the 95% prediction intervals.Closed circles represent metal concentrations not used for regression purposes.

A.J. Marmolejo-Rodrıguez et al. / Marine Pollution Bulletin 55 (2007) 459–468 463

ARTICLE IN PRESS

>2000 mg kg�1 Costa et al. (2003) attribute this to a natu-ral anomaly. In the Marabasco system an anomaly was not

Please cite this article in press as: Marmolejo-Rodrıguez, A.J. et al.Mar. Pollut. Bull. (2007), doi:10.1016/j.marpolbul.2007.09.008

found, only higher concentrations in the vicinities of theiron ore mine.

, Total and labile metals in surface sediments of the tropical ...,

Table 2Concentrations range and background levels (BL) in the fine (<63 lm) fraction from Marabasco system surface sediments, compared with other important coastal areas and the earth’s crust

Al Cd Co Cu Fe Ni Pb Zn Reference

World areas and earth’s crust

average

Sediment fraction

Tropical Kranji estuarySingapore

<63 lm – 0.19 – 17.27 – 26.12 26.13 62.12 Cuong and Obbard(2006)

Tropical Pulau estuarySingapore

<63 lm – 0.06 – 7.71 – 17.08 29.80 49.76 Cuong and Obbard(2006)

Teifi UK estuary <100 lm – 0.2 10 13 18.4 23 25 87 Bryan and Langston(1992)

Tomales Bay USA <63 lm 3.5 ± 0.3 – – 20–28 34 ± 2 116 ± 11 3–5 70–85 Hornberger et al.(1999)

Tropical Juru Penang. estuaryMalaysia

<2000 lm 6.4 ± 1.6 0.13 ± 0.05 5.1 ± 1.0 17.2 ± 10.5 21.6 ± 6 32.6 ± 6.7 27.4 ± 7.3 60.1 ± 15.5 Khalik et al. (1997)

Earth’s crust Total fraction 8.25 0.2 25 55 – 75 12.5 70 Taylor (1964)Earth’s crust Total fraction 8.41 0.08 26.6 27 52 59 11 72 Rudnick and Gao

(2003)Tinto Odiel river Spain <63 lm Cu mine influenced – 0.35–68 11–36 54–2920 42.9–264 12–47 46–1140 143–3150 Morillo et al. (2002)Tinto Odiel estuary Spain 2000–63lm Cu mine

influended– 0.67–5.30 – 341–37.2 50–170 – 232–3212 227–3998 Lopez-Gonzalez et al.

(2006)Gualaxo river, Minas Gerais,

Brazil<63 m Fe mine influenced 14.5 ± 14.1 0.14 ± 0.14 15.7 ± 10.3 42.4 ± 49.2 341 ± 106 168 ± 462 13.5 ± 11.9 34.3 ± 20.0 Costa et al. (2003)

1.2–47.3 0.02–0.66 1.6–47 6.6–267 106–501 3.5–2380 2.1–63 7.7–100 2003Mandovi estuary, India Coarse fraction Fe mine

influenced– – 2–45 11.5–77.5 22–497 – 4.5–46.5 19.9–83.5 Alagarsamy (2006)

Marabasco system Range 23.5–127.3 0.047–0.34 6.0–94.5 19.3–96.2 25.7–69.7 8.52–26.1 2.3–17.8 52.3–79.3 This studyMarabasco system BL (<63 lm) 0.086 ± 0.032 11.7 ± 4.1 44.1 ± 19.8 43.6 ± 12.3 14.2 ± 4.4 8.7 ± 3.9 90.3 ± 31.2 This studyAverage Marabasco river NEF (<63 lm) – 3.8 ± 1.2 9.8 ± 11.1 2.6 ± 2.8 2.1 ± 0.6 2.4 ± 1.5 1.0 ± 0.2 1.2 ± 0.8 This studyAverage Marabasco estuary NEF (<63 lm) – 1.2 ± 0.9 0.95 ± 0.13 0.9 ± 0.4 1.0 ± 0.4 1 ± 0.4 1.0 ± 0.2 1.0 ± 0.1 This studyMarabasco system NEF range – <0.3–4.9 <0.7–25.5 0.5–6.7 0.9–2.9 0.8–4.5 0.8–1.2 0.8–1.7 This study

Values are given in mg kg�1 except for Al and Fe (mg g�1).

464A

.J.

Ma

rmo

lejo-R

od

rıgu

ezet

al.

/M

arin

eP

ollu

tion

Bu

lletin5

5(

20

07

)4

59

–4

68

Please

citeth

isarticle

inp

ressas:

Marm

olejo

-Ro

drıgu

ez,A

.J.et

al.,T

otal

and

labile

metals

insu

rfacesed

imen

tso

fth

etro

pical

...,M

ar.P

ollu

t.B

ull.

(2007),d

oi:10.1016/j.m

arpo

lbu

l.2007.09.008

AR

TIC

LE

INP

RE

SS

A.J. Marmolejo-Rodrıguez et al. / Marine Pollution Bulletin 55 (2007) 459–468 465

ARTICLE IN PRESS

3.1.6. Zinc

According to previous studies, the iron ore of Pena Col-orada does not have high concentrations of Zn (Corona-Esquivel and Henrıquez, 2004; Marmolejo-Rodrıguezet al., unpublished data). Despite being associated withiron, Zn did not show enrichment in the Marabasco systemand its contents (range 52.3–179 mg kg�1) are similar toother World coastal areas (Fig. 2, Table 2). Comparativecontents of Zn are also observed in the other two systemsinfluenced by iron ore mines: Gualaxo river and Mandoviestuary (Costa et al., 2003; Alagarsamy, 2006; respectively).In sediments influenced by Cu mines the Zn contents areincreased to 3998 mg kg�1, Lopez-Gonzalez et al. (2006)attribute this to the acid mine drainage.

Cobalt, Cu, Fe and Ni are enriched elements in agree-ment with the regional background level in the Marabascoriver, with NEFs (mean ± standard deviation) of 9.8 ±11.1, 2.6 ± 2.8, 2.1 ± 0.6, and 2.4 ± 1.5, respectively (Table2). Cobalt, Cu and Ni present highest NEFs in the minezone (st. B) and in the st. D. Background values foundfor Co, Fe and Cu are higher than for other coastal systems(Table 2). The influence of the Pena Colorada iron mine, inaccordance with the NEF of the elements calculated in thisstudy, is lower than in other systems affected by Cu and/orFe ores (e.g. Table 2). Lead showed terrigenous behaviour,with the maximum values lower than reported backgroundconcentrations in Kranji and Pulau estuaries (Cuong andObbard, 2006), Juru Pengang estuary (Khalik et al.,1997) and Teifi estuary (Bryan and Langston, 1992). Thosesystems are without mine influence (Table 2).

The association of elements was studied using principalcomponent analysis (PCA). Fig. 4a shows the results forthe total metal concentrations normalised with Al. 86%of total variance was represented by Factor 1 (73% of var-iance) indicates elements associated with Fe (Cd, Co, Cu,Ni, Zn) and Factor 2 (13% of variance), is represented byPb, which indicates the terrigenous origin and is in accor-dance with the high correlation between Pb and Al(r2 = 0.82; Fig. 2).

3.2. Metal labile fraction

Cadmium, Co, Ni and Zn showed the highest percent-ages of labile fraction in the Marabasco system, and theirranges being between 20 and 100%, 0 and 35%, 3 and16%, 0 and 25%, respectively. The labile fraction was lowerfor Fe (<3.8%), Cu (<2.7%), and Pb (<1.2%). The spatialdistributions of the labile fraction are shown in Fig. 3.

3.2.1. Cadmium

The range in the Marabasco river was 0.035–0.17 mg kg�1, representing 23–70% of labile Cd. In theestuary, Cd showed higher percentages of labile fraction,specifically sites 2, 4 and 6 with >91 %, although in thosestations their contents (Fig. 3, Table 2) were relativelylow (0.084, 0.074 and 0.052 mg kg�1). However, estuarine

Please cite this article in press as: Marmolejo-Rodrıguez, A.J. et al.Mar. Pollut. Bull. (2007), doi:10.1016/j.marpolbul.2007.09.008

conditions promote almost total mobility of labile Cd,due to the change in salinity (Waeles et al., 2005). Higherconcentrations were found in SPM in a previous study(Shumilin et al., 2005) were Cd concentrations increasedin the estuary (salinities between 0.7 and 17.1). This coin-cides with the points with greater percentage in labile frac-tion. This element is the most labile in the Marabascosystem in accordance with other studies (Filgueiras et al.,2004; Korfali and Davies, 2005; Lee et al., 2005).

3.2.2. Cobalt

The river sampling sites have higher concentration ofcobalt than the estuary (Fig. 3, Table 2). In the mine sta-tion the percentage of labile fraction was only 3.6%. Thisis due to the high concentration of the metal in this sam-pling site (94.5 mg kg�1 in total content). This sampling sitecorresponds to labile concentration 3.4 mg kg�1. It is thehighest concentration of labile fraction of Co in all the sys-tem, in contrast with the values in the river (<1 mg kg�1).In the estuary, total Co concentrations are lower (6–20 mg kg�1) but more labile (7–31%, with total concentra-tions of 0.64–3.36 mg kg�1). Similar percentages of labileCo have been reported for other mine impacted systems(e.g. Morillo et al., 2002).

3.2.3. Nickel

Nickel is relatively more mobile in the river (0.84–3.2 mgkg�1 and 4.9–14.7%) than in the estuary (0.43–2.0 mg kg�1

and 3.5–11.7%, respectively; Fig. 3). Percentages and totalcontent are similar than those found by other authors formarine sediment (Cuong and Obbard, 2006), and river sed-iment (Filgueiras et al., 2004) both systems without mineinfluence.

3.2.4. Zinc

In the Marabasco system the minimum and maximumcontents of labile Zinc are 0.68 and 16.6 mg kg�1 and per-centages of 1–16.2%. These values correspond to the minestation (st.B) and st. D, respectively. In the estuary thelabile Zinc contents are relatively homogeneous (Fig. 3).Percentages are similar to those found in systems withoutmining influence (e.g. Cuong and Obbard, 2006), but lowerthan in other impacted mine discharges (e.g. 50% of labilefraction; Morillo et al., 2002).

Copper, Fe and Pb showed the lowest percentages oflabile fraction in the Marabasco system. Labile Cu con-tents (<2.2 mg kg�1) represent 2.7% in the river and it isalmost negligible in the estuary, where maximum contentof labile fraction is 1.0 mg kg�1. The labile Fe fractionwas not found in the river sampling sites (Fig. 3). In theestuary the iron ionic exchange occurs on a very low scale(percentage range 0–3.8% corresponding to 0.2–1.3 mg g�1). The lowest percentages of labile fraction wereobtained for Pb (Fig. 3). This element had <1% and almostnegligible concentrations (<0.083 mg kg�1). Similar per-centages were previously reported for other systems (e.g.

, Total and labile metals in surface sediments of the tropical ...,

ABCDE12345678

Cd

(mg

kg-1

)

0.0

0.1

0.2

0.3

ABCDE12345678

Co

(mg

kg-1

)

0

20

40

60

80

100

ABCDE12345678

Cu

(mg

kg-1

)

0

30

60

90

120

ABCDE12345678

Fe

(mg

g-1 )

0

20

40

60

80

ABCDE12345678

Ni (

mg

kg-1

)

0

5

10

15

20

25

30

ABCDE12345678

Pb

(mg

kg-1

)

0

4

8

12

16

20

ABCDE12345678

Zn

(mg

kg-1

)

0

40

80

120

160

200

Fig. 3. Contents and axial distribution of metals for the Marabasco system: the height of the bars represent the total metal concentrations, whereas theblack area represents the labile concentrations. Values are given in mg kg�1 except for Fe (mg g�1).

466 A.J. Marmolejo-Rodrıguez et al. / Marine Pollution Bulletin 55 (2007) 459–468

ARTICLE IN PRESS

Cuong and Obbard, 2006; Filgueiras et al., 2004; Morilloet al., 2002).

The labile fraction association was also studied usingPCA (Fig. 4b). Three factors were extracted which describe91% of the variance: Factor 1 (39% variance), to whichbelong Fe, Co, Pb and Cd (Factor coordinated of vari-

Please cite this article in press as: Marmolejo-Rodrıguez, A.J. et al.Mar. Pollut. Bull. (2007), doi:10.1016/j.marpolbul.2007.09.008

ables: FCV = 0.88, 0.77, 0.74 and �0.75, respectively). Ironand Pb both had negligible percentages of labile fractionsimplying lower mobility in all the system. Cadmium is innegative loading because it has not relationship with otherlabile elements content. Factor 2 (30% variance) is repre-sented by nickel and copper, with Cu less labile than Ni.

, Total and labile metals in surface sediments of the tropical ...,

Cd

Fe

Pb

Zn

-1.0 -0.5 0.0 0.5 1.0

Factor 1 : 78%

-1.0

-0.5

0.0

0.5

1.0

Fact

or 2

: 13

%

Co Cu Ni

Cd

Co

Cu

Fe

Ni

Pb

Zn

-1.0 -0.5 0.0 0.5 1.0

Factor 1 : 39%

-1.0

-0.5

0.0

0.5

1.0

Fact

or 2

: 30

%

b

a

Fig. 4. Principal component analysis (PCA) of total metals normalisedwith respect to Al (a) and their labile fraction (4b).

A.J. Marmolejo-Rodrıguez et al. / Marine Pollution Bulletin 55 (2007) 459–468 467

ARTICLE IN PRESS

Both elements are labile in the river mine zone. Zinc, whichdetermined factor 3 (22% variance FCV = 0.85) showsindependent behaviour.

4. Conclusions

The iron ore mine of Pena Colorada has not caused neg-ative impact in the superficial sediments of the Marabascosystem. The total contents of all elements in this study arelower compared to other World coastal areas impacted bymetallic ores. Normalised enrichment factors with respectto Al for Cd, Co, Cu, Fe, Ni, and Zn in fine fraction arehigher in river sampling sites than in the estuary and all

Please cite this article in press as: Marmolejo-Rodrıguez, A.J. et al.Mar. Pollut. Bull. (2007), doi:10.1016/j.marpolbul.2007.09.008

of them are associated with the iron ore. In the Marabascosystem the elements which could be more easily released tothe water phase were Cd, Co, Ni, and Zn, and showing alow mobility Cu, Fe, and Pb. Labile Fe is not released inthe area, its percentage being less than 4%. Cadmium isthe most labile element, reaching percentages of 100%in the estuary but its total contents are low (<0.4 mg kg�1)compared with other world coastal systems.

Acknowledgements

Authors acknowledge the help of Dr. Ana Filgueiras forlaboratory analysis, and Dr. Rodolfo Corona-Esquivel forhis comments. Marmolejo-Rodrıguez would like to thankto COFAA-COTEPABE-IPN (Mexico), for financial sup-port. This work was partially supported by a grant fromthe Consejo Nacional de Ciencia y Tecnologıa (CONACyTproject 32462T, Mexico) and to ‘‘METRIA’’ project, fi-nanced by CICYT (ref. REN2003-04106-C03, Spain).

References

Alagarsamy, R., 2006. Distribution and seasonal variation of trace metalsin surface sediments of the Mandovi estuary, west coast of India.Estuarine Coastal and Shelf Science. 67, 333–339.

Bryan, G.W., Langston, W.J., 1992. Bioavailability, accumulation andeffects of heavy metals in sediments with special reference to UnitedKingdom estuaries: a review. Environmental Pollution 76, 89–131.

Chester, R., 2003. Marine Geochemistry. Blackwell Publishing.Cobelo-Garcıa, A., Prego, R., 2004. Influence of point sources on trace

metal contamination and distribution in a semi-enclosed industrialembayment: The Ferrol Ria (NW Spain). Estuarine Coastal and ShelfScience 60, 695–703.

Corona-Esquivel, R., Henrıquez, F., 2004. Modelo Magmatico delyacimiento de hierro Pena Colorada, Colima, y su relacion con laexploracion de otros yacimientos de hierro en Mexico. Instituto deGeologıa (UNAM). Boletın 113, pp. 1–97 (in Spanish).

Corona-Esquivel, R., Tritlla, J., Henrıquez, F., Morales-Isunza, A., Luz-Portugal, J., Nava-Perez, L. Geologıa y mineralizacion del yacimientode hierro Pena Colorada, Colima. In: Salas, Clark (Eds.), Fondo deCultura Economica ‘‘Geologıa Economica de Mexico’’, second ed. (inpress).

Costa, A.T., Arias, N.H., Carvalho, L.J., Friese, K., Mages, M., 2003.Surface water quality and sediment geochemistry in the Gualaxo doNorte basin, eastern Quadrilatero Ferrıfero, Minas Gerais, Brazil.Environmental Geology 45, 226–235.

Cuong, D.T., Obbard, J.P., 2006. Metal speciation in coastal marinesediments from Singapore using a modified BCR-sequential extractionprocedure. Applied Geochemistry 21, 1335–1346.

EPA., 1996. Method 3052, Microwave assisted acid digestion of siliceousand organically based matrices. Available from h<www.epa.gov/epaoswer/test/3052pdfi>.

Filgueiras A.V., 2004. Extraccion secuencial de metales pesados ensedimentos: Desarrollo de metodos rapidos y aplicaciones. PhD.,Thesis. Facultad de Quımica. Universidad de Vigo, p. 340 (inspanish).

Filgueiras, A.V., Lavilla, I., Bendicho, C., 2004. Evaluation of distribu-tion, mobility and binding behaviour of heavy metals in suricialsediments of Louro River (Galicia, Spain) using chemometric analysis:a case study. Science of the Total Environment 330, 115–129.

Hakanson, L., 1980. An ecological risk index for aquatic pollutioncontrol. A sedimentological approach. Water Research 14, 975–1001.

Hanson, P.J., Evans, D.W., Colby, D.R., 1993. Assessment of elementalcontamination in estuarine and coastal environments based on

, Total and labile metals in surface sediments of the tropical ...,

468 A.J. Marmolejo-Rodrıguez et al. / Marine Pollution Bulletin 55 (2007) 459–468

ARTICLE IN PRESS

geochemical and statistical modeling of sediments. Marine Environ-ment Research 36, 237–266.

Hornberger, M.I., Luoma, S.N., van Geen, A., Fuller, C., Anima, R.,1999. Historical trends of metals in the sediments of San FranciscoBay, California. Marine Chemistry 64, 39–55.

Kerstern, M., Forstner, U., 1991. Speciation of trace elements insediments. In: Batley, G.E. (Ed.), Trace Element Speciation: Analyt-ical Methods and Problems. CRC Press, Boca Raton, Fl, pp. 245–317.

Khalik, A., Wood, A., Ahmad, Z., Azhar, N., Shazili, M.D., Yaakob, R.,Carpenter, R., 1997. Geochemistry of sediments in Johor straitbetween Malaysia and Singapore. Continental Shelf Research 17,1207–1228.

Korfali, S.I., Davies, B.E., 2005. Seasonal variation of trace metalchemical forms in bed sediments of a karstic river in Lebanon:implications for self-purification. Environmental Geochemistry andHealth 27, 385–395.

Lee, S.E., Lee, J.S., Chon, H.T., 2005. Environmental contamination ofheavy metals and effects of sediment bacteria on cadmium speciation inthe vicinity of the Hwacheon mine. Key Engineering Materials, 277–279, 438–444.

Lopez-Gonzalez, N., Borrego, J., Morales, J.A., Carro, B., Lozano-Soria,O., 2006. Metal fractionation in oxic sediments of an estuary affectedby acid mine drainage (south-western Spain). Estuarine, Coastal andShelf Science 68, 297–304.

Marmolejo-Rodrıguez, A.J., Prego, R., Meyer-Willerer, A., Shumilin, E.,Sapoznikov, D., 2007. Rare earth elements in iron oxy-hydroxide richsediments from the Marabasco river-estuary system (Pacific coast ofMexico). REE affinity with iron and aluminium. Journal of Geo-chemical Exploration 94, 43–51.

Marmolejo-Rodrıguez, A.J., Prego, R., Cobelo-Garcıa, A., Meyer-Wil-lerer, A., Shumilin, E., unpublished data. Background values, distri-bution and enrichment of major and trace elements in a tropicalcoastal system impacted by mining activities (Marabasco System,Mexico).

Morillo, J., Usero, J., Garcıa, I., 2002. Partitioning of metals in sedimentsfrom the Odiel River. Environment International 28, 263–271.

Quevauviller, P., Rauret, G., Lopez-Sanchez, J., Rubio, R., Ure, A.M.,Muntau, H., 1997. The certification of the EDTA-extractable contents

Please cite this article in press as: Marmolejo-Rodrıguez, A.J. et al.Mar. Pollut. Bull. (2007), doi:10.1016/j.marpolbul.2007.09.008

(mass fractions) of Cd, Cr, Ni and Zn in sediment following a three-step sequential extraction procedure. Report EUR 17554 EN Brussels.

Rauret, G., Lopez-Sanchez, J.F., Sahuquillo, A., Rubio, R., Davidson, C.,Ure, A., Quevauviller, P., 1999. Improvement of the BCR three stepsequential extraction procedure prior to the certification of newsediment and soil reference materials. Journal of EnvironmentMonitor 1, 57–61.

Reimann, C., Caritat, P., 2005. Distinguishing between natural andanthropogenic sources for elements in the environment: regionalgeochemical surveys versus enrichment factors. Science of the TotalEnvironment 337, 91–107.

Rubio, B., Nombela, A., Vilas, F., 2000. Geochemistry of major and traceelements in sediments of the Ria de Vigo (NW Spain): an assessment ofmetal pollution. Marine Pollution Bulletin 40, 968–980.

Rudnick, R.L., Gao, S., 2003. The composition of the continental crust.In: Holland, H.D., Turekian, K.K. (Eds.), The Crust. Treatise on theGeochemistry, 3, pp. 1–64.

Shumilin, E., Meyer-Willerer, A., Marmolejo-Rodriguez, AJ., Morton-Bermea, O., Galicia-Perez, M.A., Hernandez, E., Gonzalez-Hernan-dez, G., 2005. Iron, cadmium, chromium, copper, cobalt, lead, andzinc distribution in the suspended particulate matter of the tropicalMarabasco River and its estuary, Colima, Mexico. Bulletin ofEnvironmental Contamination and Toxicology 74, 518–525.

Taylor, S., 1964. Abundance of chemical elements in the continental crust:a new table Geochimica et. Cosmochimica Acta 28, 1273–1285.

Tuna, A.L., Yilmaz, F., Demirak, A., Ozdemir, N., 2007. Sources anddistribution of trace metals in the saricay stream basin of southwesternturkey. Environment Monitoring Assessment 125, 47–57.

Vangronsveld, J., Cunnihgham, S.D., 1998. Metal Contaminated Soils: In-Situ Inactivation and Phytoremediation. Springer Verlag, Berlin.

Waeles, M., Riso, R.D., Le Corre, P., 2005. Seasonal variations ofcadmium speciation in the Penze estuary NW France. EstuarineCoastal and Shelf Science 65, 143–152.

Willerer, A.O.M., Kot, F.S., Shumilin, E.N., Lutsarev, S., Rodrıguez,A.J.M., 2003. Mercury bottom sediments of the tropical rio Mara-basco, its estuary and Laguna de Navidad Mexico. Bulletin ofEnvironmental Contamination and Toxicology 70, 1213–1219.

Zhang, J., 1995. Geochemistry of trace metals from chinese river/estuarysystems: an overview. Estuarine Coastal and Shelf Science 41, 631–658.

, Total and labile metals in surface sediments of the tropical ...,