INTEGRATED ASSESSMENT AND MANAGEMENT OF THE

ECOSYSTEMS AFFECTED BY THE AZNALCÓLLAR MINING

SPILL (SW, SPAIN)

Edited by

Ángel del Valls Departamento de Química Física

Universidad de Cádiz

Spain

Julián Blasco Departamento de Oceanografía

Instituto de Ciencias Marinas de Andalucía

Consejo Superior de Investigaciones Científicas

Spain

2005

I.S.B.N. 84-609-7200-3

Imprime: Encuadernaciones Martínez, Puerto Real (Cádiz)

Septiembre, 2005

CONTENTS

PRÓLOGO……………………………………………………………………………...I

PREFACE…………………………………………………………………………..….III

CHAPTER 1. ENVIRONMENTAL IMPACT ASSESSMENT

1.1. TERRESTRIAL ECOSYSTEM

The Effect of Soil Amendments on the Bio-availability of Heavy Metals in Soil

Contaminated by the Aznalcóllar Mine Spill. M.P. Bernal, R. Clemente, A. Roig, D.J.

Walker……………………..………………………………………………………..……..3

Biochemical Biomarkers of Pollution in Algerian Mouse (Mus spretus) to assess

the biological effects of Aznalcóllar Mining spill. J. López-Barea, J. Ruiz-Laguna, D.

Bonilla, A. Muñoz, S. Moreno………...……………………………………..………….11

Phytorremediation of a Metal Contaminated Area in Southern Spain. E. Alcántara,

R. Barra, M. Benlloch, A. Ginhas, J. V. Jorrín, J.A. López, Á Lora, M. A. Ojeda, M.

Puig, A. Pujadas, R. Requejo, J. Romera, J. Ruso, E. D. Sancho, S. I. Shilev, and M.

Tena.................................... ................................................................................21

Morphohydrological elements and unites from entremuros (Nacional Park of

Doñana) to restore its original dynamics. R. Baena Escudero and I. Guerrero

Amador……………………………………………………….………………...………..27

Effect of Remediation on Trace Metal Pollution in Soils of Guadiamar River

Valley. F. Cabrera, L. Clemente, R. Cordón, M. D. Hurtado, R. López, P. Madejón, T.

Marañón, F. Moreno, J. M. Murillo, I. Nagel……………...……………………….……..33

Biomonitoring of genetic damage on Algerian Mouse (Mus spretus) as a sentinel

species in Doñana Nacional Park (1995-2000). M. Cristaldi, G. Chiuchiarelli, L.A.

Ieradi, C. Tanzarella, R. Cozzi, R. Grossi, L. Campanella, S. Moreno……………...…..41

Differential Accumulation of Pb, Zn and Cu by Brassica Species Grown in the

Polluted Soils of Aználcollar (Southern Spain). M. Del Río, R. Font, A. De

Haro…………………………………………………………….………………………..55

Heavy metal analysis of polluted soils by Near-Infrared Spectroscopy. R. Font, M.

Del Río, M. Simón, J. Aguilar, A. De Haro…………… ……………………………..….61

Microbial and Enzyme Activities as Functional Indicators of Soil Quality in a

Riparian Ecosystem Affected by the Aznalcollar Mine Spill. M. B. Hinojosa, R.

García-Ruíz, B. Viñegla, J. M. Maroto, J. M. Martín, M.V. Ochoa, J. C. Linares, J. A.

Carreira…………………………………………………...……………………… …….71

Heavy metal and arsenic accumulation by wild vegetation in the Guadiamar River

area: implications for phytoremediation. M. Del Río, R. Font, C. Almena, D. Vélez, R.

Montoso, A, De Haro…………………………………………………….………………81

Evolution of Arsenic, Lead, Iron and Manganese in Evergreen Trees Affected by

the Aznalcóllar Mine Spill. P. Madejón, T. Marañón, J.M. Murillo and F.

Cabrera……………………………………………………………………….………….91

Study of the Nematode Fauna (Dorylaimida and Mononchida) in affected areas of

the Guadiamar River Basin: Preliminary Results. R. Peña-Santiago, D. Jiménez-

Guirado, G. Liébanas, R. Murillo, J. Abolafia and P. Guerrero………………................99

Assessment of Residual Soil Contamination after the Aznalcóllar Mining Accident

(Spain) Using Multitemporal Imaging Spectroscopy and Spectral Mixture

Analysis. T. Kemper, S. Sommer, J. Garcia Haro………………………………..…..105

1.2. AQUATIC ECOSYSTEM

1.2.1. FLUVIAL ECOSYSTEM

Human impacts and riparian conservation status in the last 67 km of the

Guadiamar river. C. Arribas, P. Guarnizo, T. Saldaña and C. Fernández-

Delgado……………………………….………………………………………………..115

Modelling Water and Sediment Transport in the Guadiamar Catchment. C. Conan,

F. Bouraoui and G.Bidoglio....................................................................................125

Evolution of heavy metal concentrations in water, sediment, plankton, biofilms

and macroinvertebrates in the Guadiamar river after the Aznalcóllar incident. C.

Solà, J. Toja, M. Plans, N. Prat……………………………………….………………135

Assessing Metal Bioavailability After a Mine Tailings Spill with Metallothionein-

Like Protein and Tissue Metal Concentrations in T. tubifex. P. L. Gillis, T. B.

Reynoldson, D. G. Dixon and D. Milani…………………………..…………………….145

Sediment Toxicity in the Rio Guadiamar (Spain), after a Tailings Dam Collapse.

T.B. Reynoldson and D. Milani ………………………….……………………………..153

Effect of the toxic waste spill (Aznalcóllar mine accident) on the levels of heavy

metals in different organs of the Guadiamar river fish. R. Moreno-Rojas, M.J.

Gordillo-Otero, A. Sánchez-Palenzuela, T. Saldaña, C. Arribas and C. Fernández

Delgado……………………………………………………….…………………….….165

1.2.2. ESTUARINE ECOSYSTEM

The Fish Community of the Guadalquivir Estuary (SW Spain) after the Toxic Spill

of the Aznalcóllar Mine. D. García-González, F. Faldó, P. Drake, A.M. Arias, P.

Guarnizo, C. Fernández-Delgado...........................................................................175

Transport of Heavy Metals, Nutrients and Inorganic Carbon in the Guadalquivir

Estuary. I. Sáenz Arteche, T. Ortega Díaz, R. Ponce Alonso, M. de la Paz Arándiga, J.

M. Forja Pajares, A. Gómez Parra……………………….…………………………….185

Temporal Evolution of Heavy Metals in the Guadalquivir Estuary after the

Aznalcóllar Mining Spill. Sáenz, I., Forja, J.M. and Gómez-Parra, A………...…......195

The Guadalquivir River Estuary. Its relation to Aznalcóllar Disaster. J.L. Fernández

Martín…………………………………………………………………………....……..203

Temporal Trends in the Levels of Heavy Metal Contamination in the Species of

the Guadalquivir River Estuary after the Aznalcóllar Accident J. Blasco, A.M. Arias,

V. Sáenz, I. Moreno-Garrido, M. Fernández-Bastón, R. González-Pascual T.

Ransome……………………………………………………………………..…..…….211

Semi-Empiric Models to Assess the Influence of the Aznalcollar Mining Spill in

the Heavy Metals Speciation in the Guadalquivir Estuary. E. García-Luque, J.M.

Forja, A. Gómez-Parra…………………………………...…………………………….217

Integrated approach of the adverse effects produced by the Aznalcollar mining

spill in the sediment. I. Riba, M.L. Martín-Díaz, J.M. Forja and T.A. DelValls

………………………………………………………………………………………….225

Integrated approach of the adverse effects produced by the Aznalcollar mining

spill in the aquatic environment. M.L. Martín-Díaz, I. Riba, D. Sales and T. A.

DelValls…………………………………………………………………………………235

1.3. SOCIO-ECONOMIC IMPACT

The Breakage of the Tailings Pond of the Aznalcollar Mines . A. Gil Toja, J.M.

Moreira Madueño, J. Serrano Aguilar………………………………………..………..249

The Doñana Mining accident and its consequences – a background document.

WWF…………………………………………………………………..…….…….……259

Retrospective Analysis of Space Utilisation at the Guadiamar River Basin. Y.

Jiménez Olivencia, A. Paniza Cabrera, J. Gómez Zotano………………………..…..279

CHAPTER 2. ENVIRONMENTAL RISK ASSESSMENT

The Aznalcóllar Spill: Possible Impacts and Conflicts on the Atlantic Coastal Area

J. C. Rodríguez Mateos………………………………………………………………...289

CHAPTER 3. INTEGRAL MANAGEMENT OF THE ECOSYSTEM

A review of marsh land uses afected by the Aznalcóllar mining spill. A. Macías

Bedoya……………………………………………………………….………………. 299

The Subsystem of Information of Guadiamar. A. Gil Toja, J.M. Moreira

Madueño..............................................................................................................315

Mining and the water environment: Lessons from an Assessment of Water

Pollution during the full Life-Cycle of a Metalliferous Mine. L. Santamaría…..….223

Mapping and modelling land use changes in the Guadiamar Catchment. M.J.

Prados-Velasco, A. Doctor-Cabrera and V. López, Reyes………………………….…333

Evaluation of the Affected Surfaces by the Spill of Mines of Aznalcollar. J.M.

Moreira Madueño, M. Rodríguez Surian, A. Ortiz Nieto, M. García Padilla and A. Gil

Toja……………………………………………………………………………..… ….345

CHAPTER 4. REMARKS

The impact of the Aznalcóllar minning spill onto the Guadalquivir estury: lessons

to learn. T.A. DelValls and A. Gómez-Parra……………………………………...…...355

The Aznalcóllar accident (April 1998) - some comments. P. M. Chapman….......371

The Development of European Policies After Recent Mine Spills. A. M.

Kroll.....................................................................................................................375

Chapter1 - Terrestrial ecosystem

71

MICROBIAL AND ENZYME ACTIVITIES AS FUNCTIONAL INDIC ATORS OF SOIL QUALITY IN A RIPARIAN ECOSYSTEM AFFECTED BY TH E

AZNALCOLLAR MINE SPILL 1M. B. Hinojosa, 1R. García-Ruíz, 1B. Viñegla, 2J. M. Maroto, 3J. M. Martín, 1M.V.

Ochoa, 1J. C. Linares, 1J. A. Carreira.

1Departamento de Biología Animal, Vegetal y Ecología. Facultad de Ciencias Experimentales B-3, Universidad de Jaén. Paraje Las Lagunillas s/n, 23071 Jaén (Spain)

2Departamento de Ingeniería Química, Facultad de Ciencias, Universidad de Málaga. Campus de Teatinos s/n , 29071 Málaga (Spain)

3Departamento de Geología. Facultad de Ciencias Experimentales B-3, Universidad de Jaén. Paraje Las Lagunillas s/n, 23071 Jaén (Spain)

Correspondence to: J. A. Carreira Phone number: +34 953 00 25 51

Fax number: +34 953 01 21 41 E-mail: jafuente@ujaen.es

Abstract We assessed the soil status, in terms of microbiological functionality, in a riparian ecosystem affected by the Aznalcollar mine spill, shortly after restoration practices were undertaken (withdrawal of heavy metal-rich muds and top-soil, and liming of the remaining surface soil). We measured general (N-mineralization, nitrification, denitrification, respiration) and enzymatic (phosphatase, dehydrogenase, urease,-glucosidase, arilsulfatase) microbiological activities, as well as physico-chemical properties (including heavy-metal bioavailability), on three plots with comparable soils and riparian vegetation, but that were either i) unaffected by the pyrite-mud flood (“positive control” or “reference” plot), ii) affected and cleaned (“treated” plot) or iii) affected but not cleaned (“negative control” or “maximum impact” plot). Values at the “reference” plot are considered “optimal restoration targets”, and differences between “maximum impact” and “treated” plots are expressed as relative recovery achieved up to now by restoration practices. Results show the success of restoration practices under conventional chemical criteria, but the quality of restored-soils is still low in biochemical functional terms (in part due to restoration practices side-effects, such as withdrawal of the top-soil). It is concluded that, in addition to measurements of heavy-metal contents, microbiological activities should be included in on-going, long-term, monitoring programmes of soil-quality in the restored areas of the Corredor Verde. On 25 April 1998, the residues pond of the Aznalcollar mine collapsed, and 2 Hm3 of pyritic muds and 4 Hm3 of acid- and heavy metal-enriched waters were released into the Agrio river, affecting over 4.600 ha of the Guadiamar basin, which drains into Doñana National Park (SW Spain). Restoration practices

72

“NEGATIVE CONTROL”

OR “MAXIMUM IMPACT”

PLOT

TREATEDPLOT

N-NSN-APM

N-PM

N-BPM

N-NA0

N-NA5

T-NS

T-NA0

P-NA0

P-NA5T-NA5

0 cm

3.8 cm4.2 cm

0 cm0 cm

5 cm

15 cm

4.8 cm

9.8 cm

19.8 cm

22.5 cm

27.5 cm

32.5 cm

42.5 cm

“POSITIVE CONTROL”

OR “REFERENCE”

PLOT

included the mechanical withdrawal of pyritic muds and top-soils over most of the affected area, and subsequent liming of the remaining soils. Traditionally, the monitoring of the residual contamination, and post-impact recovery in the short-to-medium terms, is approached by analytic chemical methods based on the direct measurement of the contaminant levels (Young et al. 1997). However, heterogeneity in initial composition and dose, and further physico-chemical and biological transformations, of the contaminants, as well as intrinsic variability in the characteristics of the receptor system, introduce high uncertainty in the extrapolation of ecological effects from such sort of data. The use of bioindicators is an alternative approach. Within the wide range of bioindicators

Figure 1. Location of sampling plots and diagrams of the different soil layers that were sampled in each plot. that are available, enzymatic and microbiological activities related to the C, N, P and S cycling through the soil organic matter, typically show high sensibility and short-time response under stress (Nannipieri 1994; Yakovchenko et al. 1996), particularly that induced by heavy metals contamination (Giller et al. 1998). Thus, they might be used as functional indicators of post-impact soil recovery. Prior to the application of this approach to the whole range of soils and areas affected by the Aznalcollar mine spill, we carried out a preliminary test (presented here) to check the suitability of enzymatic and microbiological activities to assess the degree of soil-quality recovery in functional terms, in a selected, “target”, riparian-forest ecosystem.

Doñana National

Park

AtlanticOcean

Chapter1 - Terrestrial ecosystem

73

Material and methods Three study plots were selected (Figure 1), representing comparable riparian ecosystems (mixed Populus, Fraxinus and Eucalyptus forest on sandy-loam fluvisols in the proximal alluvial plain) but that were either i) unaffected by the pyritic-mud flood (“positive control” or “reference” plot, located on the Molinillo stream which discharge on the Guadiamar river, and less than 1 km apart from the other plots), ii) affected but subsequently cleaned (“treated” plot), and iii) affected and left with the mud on top of the soil (“maximum impact” or “negative control”). The treated and negative control plots were less than 100 m apart. In November 2000, three positions in the “maximum impact” plot, and five positions in the “reference” and “treated” plots, were randomly selected. Soil samples (composed of three subsamples) were collected at different depth (Figure 1), depending on the presence and width of a post-impact, newly-deposited, top-sediment layer (NS-layer), an above-pyritic-mud, oxidised layer (APM-layer), a pyritic-mud layer (PM-layer), and a below-pyritic-mud layer (BPM-layer). Non-affected, 0-5 cm (NA0-layer) and 5-15 cm (NA5-layer) depth, soil samples were also collected on top of the reference plot, below the newly-deposited sediment in the treated plot, and below the lowest oxidised layer in the control plot. Soil samples were stored in plastic bags on ice, and transported to the lab in less than 2 days. Three group of variables were analysed in soil samples: general physico-chemical properties including heavy metal availability, and general microbiological, and specific enzyme, activities related to the C, N, P and S cycles. Fresh soil samples were sieved (2 mm mesh). 20 g subsamples were analysed by conventional methods for water content (expressed as % on soil dry basis) and % loss-on-ignition. The remaining soil was air-dried. Soil pH (1:1 soil: 0.01 M CaCl2), water holding capacity (WHC) at 33 kPa in a Richard´s membrane-plate extractor (Klute 1986), labile inorganic and organic phosphorus (Olsen and Sommers 1982), and KCl -extractable ammonium and nitrate (Keeney and Nelson 1982), were determined within three weeks after soil collection. Soil respiration rates were estimated by the alkali-trap method (Anderson 1982) on soil samples incubated aerobically for one week at 80 % WHC and 25 oC. Potential N-mineralization and nitrification rates were estimated following Keeney and Nelson (1982) on soil samples incubated aerobically for one month at 80 % WHC and 25 ºC. Potential denitrification rate and nitrous oxide (N2O) production were estimated following Sørensen (1978), using the acetylene-blockage technique on soil samples incubated in anaerobic conditions, at 25 oC for between 2 to 4 hours, and based on the analysis of the N2O concentration on a HP-5890 gas chromatography equipped with an EC detector. Especific enzymatic activities (dehydrogenase, phosphatase, -glusosidase, arilsulfatase and urease activities) were determinated on 1 g soil samples incubated at 37 oC following the methods described by Tabatabai (1982). Bioavailable DTPA-extractable, Cd, Pb, Cu and Zn concentrations in soil samples were determinated by AAS-Perkin Elmer 3100.

74

Results and discussion General physico-chemical properties, concentrations of available N and P, and microbiological and enzymatic activities of soils in the studied plots are shown in Table 1. In the negative control plot, the presence of a pyritic mud between 4 to 22.5 cm depth within the soil profile (PM-layer) and its influence on adjacent soil layers (APM- and BPM-layers), are clearly denoted by sharp changes in most of the analysed variables. The pH ranged between 2.1 to 3.6 in these layers, and was much more lower than in soil layers not directly affected by the pyritic-mud (NS and NA0 and NA5 layers, with pH between 6 and 8). A similar trend was found for the inorganic N and labile P concentrations, indicating a decrease in major nutrient availability in the soil layers in contact with the buried pyritic-mud. This might be related to the inhibition (heavy-metal and/or pH-related) effects of the mud on rates of organic matter mineralization by the microbiota, as suggested by concomitant decreases in general and enzymatic microbiological activities in the mud-affected soil layers. Both, general (base respiration, N-mineralization, nitrification, and denitrification and N2O production rates) and enzymatic activities related with nutrient cycling were the lowest, often undetectable, in the PM-layer, and very low in the APM- and BPM-layers. Those results are in agreement with data on the abundance of heterotrophic bacteria, which were minima (less than 102 colony-forming-units g-1 of soil) in the layers directly affected by the pyritic-mud, and increased in non-affected layers (with up to 104 cfu g-1) (de Vicente, pers. comm.). However, the direct effect of low pH itself in decreasing nutrient solubility can not be

Table 1. Physico-chemical properties and microbiological and enzymatic activities in different soil layers at: i) the negative control plot (affected and left with the mud on top of the soil), ii) the treated plot (comparable riparian ecosystem affected but subsequently cleaned), and iii) the reference plot (riparian ecosystem unafeccted by the pyritic-mud flood. (Mean + standard error).

D

EP

TH

c

m.

% w

ater

co

nten

t

% lo

ss-o

n-ig

nitio

n

WH

C

(1/3

atm

)

pH

1:

1 (C

aCl 2)

amm

oniu

m

(�g

N-N

H4+

/g)

nitr

ate

(�

g N

-NO

3-/g

)

labi

le P

i (�

g P

/g)

labi

le P

o

(�g

P/g

)

resp

iratio

n ra

te

(�m

ol C

O2/

g*d)

N-m

iner

al. r

ate

(�

g N

/g*d

)

nitr

ifica

tion

(�

gN-N

O3-/g

*d)

N2O

pro

duct

. (n

mol

N2O

h-1 g

-1)

deni

trifi

catio

n (n

mol

N2O

h-1 g

-1)

dehy

drog

enas

e

(�g

TP

F/g

*h)

acid

pho

sph.

(�

g pN

P/g

*h)

alk

al. p

hosp

h.

(�g

pNP

/g*h

)

�-g

luco

sida

se

(�

g pN

P/g

*h)

arils

ulfa

tase

(�

g pN

P/g

*h)

urea

se

(�g

NH

4+/g

*h)

NS 0-3.8 11.7 +3.5

8.2 +0.9

41.8 +0.5

6.7 +0.3

14.0 +3.3

11.0 +1.1

33.4 +3.0

38.8 +2.7

2.0 +0.2

2.9 +0.9

1.4 +0.1

0.6 +0.1

12.4 +1.2

26.2 +0.4

104.1 +1.7

70.8 +10.3

85.5 +31.6

20.0 +5.4

15.6 +6.1

APM 3.8-4.2 41.6 +8.9

12.8 + 0.3

43.4 +2.4

2.5 +0.1

7.4 +0.6

0.6 +0.1

1.2 +0.2

9.9 +0.3

3.3 +0.3

0.1 +0.1

0.0 +0.0

0.1 +0.1

0.7 +0.4

9.4 +1.1

72.3 +14.1

64.7 +9.0

102.7 +39.9

3.2 +0.1

1.4 +0.3

PM 4.2-22.5 23.5 +0.2

24.2 +0.2

23.4 +0.6

2.1 +0.1

3.9 +0.4

0.0 +0.0

0.9 +0.1

6.3 +0.6

0.0 +0.0

0.0 +0.1

0.0 +0.0

0.0 +0.0

0.1 +0.0

0.0 +0.0

0.9 +0.5

0.0 +0.0

0.0 +0.0

0.2 +0.2

0.0 +0.0

BPM 22.5-27.5

37.5 +0.3

6.3 +0.5

30.3 +0.5

3.6 +0.6

7.1 +2.1

0.2 +0.1

1.9 +0.4

5.9 +1.4

1.1 +0.3

0.1 +0.1

0.0 +0.0

0.0 +0.0

0.2 +0.0

5.2 +0.2

12.3 +2.7

77.4 +5.6

80.6 +59.0

1.4 +0.7

2.4 +0.5

NA0 27.5-32.5

33.7 +1.6

3.8 +1.2

26.6 +1.4

6.4 +0.3

11.9 +2.0

0.9 +0.3

4.9 +0.9

13.3 +2.7

1.0 +0.0

0.0 +0.0

0.0 +0.0

0.1 +0.1

0.3 +0.2

5.8 +0.9

11.4 +4.4

95.1 +10.5

11.8 +2.5

1.6 +0.5

7.0 +0.3

NA5 32.5-42.5

15.7 +0.0

6.1 +0.0

24.9 +0.0

6.5 +0.0

13.2 +0.0

0.4 +0.0

4.8 +0.0

4.5 +0.0

2.8 +0.0

0.5 +0.0

0.1 +0.0

0.1 +0.0

0.1 +0.0

6.6 +0.0

7.9 +0.0

51.6 +0.0

14.2 +0.0

2.8 +0.0

8.8 +0.0

NS 0-4.8 3.9 +0.6

5.1 +0.3

35.2 +3.4

7.0 +0.2

31.7 +5.6

6.0 +1.2

16.1 +3.3

17.6 +1.2

2.5 +0.3

0.8 +0.1

1.9 +0.2

0.3 +0.1

5.3 +0.7

20.0 +2.6

16.9 +1.7

24.2 +2.7

17.2 +0.9

6.5 +0.8

9.3 +1.7

NA0 4.8-9.8 6.9 +1.2

5.3 +0.5

18.9 +0.8

5.8 +0.5

12.4 +2.1

3.3 +0.8

6.3 +1.6

3.3 +0.6

1.2 +0.1

0.2 +0.1

0.5 +0.0

0.2 +0.0

0.3 +0.0

3.2 +0.3

18.1 +1.2

14.2 +1.6

23.8 +0.3

3.4 +0.4

4.2 +0.7

NA5 9.8-19.8 11.7 +2.6

4.8 +1.4

22.2 +0.7

6.0 +0.6

14.5 +1.6

2.6 +0.5

3.1 +0.4

5.1 +0.7

1.3 +0.0

0.3 +0.1

0.5 +0.0

0.2 +0.0

0.3 +0.0

2.0 +0.3

18.5 +0.8

36.2 +1.9

33.6 +0.8

5.0 +0.8

4.1 +0.4

NA0 0-5 12.9 +1.4

7.1 +0.3

37.0 +1.1

7.9 +0.0

8.18 +1.5

16.1 +2.9

14.6 +0.9

13.8 +1.2

2.2 +0.0

2.4 +0.3

3.5 +0.5

1.1 +0.3

8.5 +0.6

45.9 +3.3

176.2 +9.9

291.0 +4.1

68.5 +0.6

65.0 +8.2

21.5 +2.6

NA5 5-15 10.7 +0.9

4.9 +0.5

25.4 +1.4

7.5 +0.0

8.08 +1.5

3.6 +0.2

13.0 +1.4

13.4 +1.5

2.0 +0.2

1.2 +0.7

1.5 +0.4

0.7 +0.1

13.4 +1.3

29.2 +1.9

88.1 +11.7

272.9 +6.1

53.7 +0.6

29.0 +4.1

17.8 +1.1

NE

GA

TIV

E

CO

NT

RO

L

PHYSICO-CHEMICAL

GENERAL BIOGEOCHEMICAL ENZYMATIC ACTIVITIES T

RE

AT

ED

R

EF

ER .

SAMPLING PLOT AND

SOIL LAYERS

Group of soil properties

76

Table 2 . Bioavailable heavy-metal concentrations (mg/kg) in the studied soil samples

NS APM PM BPM NA0 NA5 NS NA0 NA5 NA0 NA5 Cd

1.6 +0.4

2.5 +0.3

1.3 +0.1

3.4 +0.7

2.1 +0.6

2.8 +0.3

0.4 +0.1

0.3 +0.0

0.2 +0.1

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equilibrium” displayed by soils at the “un-affected”, reference plot. Together with directs effects of the still relatively high levels of bioavailable metals, the low soilbiogeochemical activity found in the treated plot is a side-effects of the cleaning practices that removed a portion of the native top-soil, where maximum activities were likely located prior to the accident (as it is exemplify by the reference plot). In the absence of new restoration tasks (e.g., incorporation of manure) specifically aimed to the fast build-up of the surface soil organic matter content in the cleaned areas, the recovery of the degree of microbial functionality found in the reference plot will take place only in the long-term. A principal component analysis (PCA) was conducted on the whole set of variables and cases to summarize the information. The three firsts components explained a 62, 14 and 9 % of the total variance, respectively. Microbiological and enzymatic activities were the only variables which were highly and positively correlated with the PC1 (r

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Figure 2. Graphic representation of the two major planes of variation that can be defined through PCA for the whole set of results: PC1 vs PC3 or plane of soil biogeochemical functionality; and PC2 vs PC3 or plane of soil physico-chemical environment. The solid arrow represents the net recovery achieved up to now by restoration practices (“beneficial effects” minus “side-effects” –top soil removal- of treatments). On the other hand, samples from the treated (excluding newly deposited sediments) and reference plots are very close on the PC2-PC3 plane. Thus, if physico-chemical criteria would have been taken alone to assess soil quality (as is usual in monitoring studies dealing with heavy-metal contamination of soils), the conclusion would have been that the treatments applied up to now to the impacted soils have already met the considered restoration targets (pre-impact soil conditions). In summary: The use of enzyme and microbiological activities (Dick 1994; Trasar-Cepeda 1998), and standard physico-chemical variables, combined in multivariate analyses to ordinate comparable “impacted but non treated”, “treated” and “unaffected” plots, has been outlined as a suitable method for the assessment of restoration success, in terms soil-quality, if a functional approach is to be adopted within the monitoring programmes under way in the area affected by the Aznalcollar mine-spill. The enzyme and microbiological activities were consistently and highly correlated with the first Principal Component, that explained up to 62 % of the total variance and was able to separate the different pre-impact, impact, post-impact situations that were considered. This could not be achieved when only physico-chemical variables were taking into account. In terms of soil microbiological functionality, the degree of recovery of the affected and treated soils is still relatively low. Further studies are needed to monitor the recovery of soil functionality in the affected area in the long-term.

PC 3

-3 -2 -1 0 1 2

PC

1

-2

-1

0

1

2

3

PNA0

PNA5NNS

NAPM

NPM

NNA0NBPM

NNA5

TNS

TNA0 TNA5

PC 3

-3 -2 -1 0 1 2

PC

2

-2

-1

0

1

2

3

PNA0PNA5

NAPM

NNS

TNA0TNA5

TNS

NNA0

NNA5NPM

NBPM

NEGATIVE CONTROL PLOT

a) b) G

rad

ien

t of b

iog

eoch

emic

al

fun

ctio

na

lity

Phy

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chem

ical

gra

dien

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Degree of direct influence of the pyritic mud Degree of direct influence of the pyritic mud

TREATED PLOT

POSITIVE CONTROL

Impact Distance to complete optimal restoration targets

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Acknowledgements We thank Consejería de Medio Ambiente-Junta de Andalucía for supporting the present study through the research contract 5.2 of the PICOVER (Plan de Investigación del Corredor Verde del Guadiamar). We would like to express our gratitud to the staff of the Technical Office of the “Corredor Verde”, especially José M. Arenas, Javier Serrano and Vicente Morillo, for then helpful information and asistance. Vitae Dr. José A. Carreira de la Fuente is the principal researcher of the subproject 5.2 “Soil ecology and biogeochemistry”, included in the agreement “Microorganisms as bioindicators in the assessment and monitoring of the toxicity of pyritic muds spilled in the Gudiamar basin”, signed between the Consejería de Medio Ambiente-Junta de Andalucía and University of Málaga. Other members of the research team are: Dr. R. García-Ruiz and Dr. B. Viñegla (professors of Ecology) and J.M. Martín (professor of Pedology) at University of Jaén; Dr. J.M. Maroto (proffesor of Chemical Engineering at University of Málaga); M. B. Hinojosa (Ph-D student carring out her thesis on the subject) and M.V. Ochoa and J.C. Linares (collaborative BS-students) References Anderson JPE (1982) Soil respiration. In: Page AL el al. (eds) Methods of soil analysis, part 2 Chemical and Microbiological Properties, 2 ed. ASA-SSSA, Madison, WI, USA Dick RP (1994) Soil enzyme activities as indicators of soil quality. In: Doran JW, Coleman DC, Bezdicek DF y Stewart BA (eds) Defining Soil Quality for a Sustainable Environment. SSSA,Speac Pub No 35, Madison, WI, USA Giller KE, Witter E, McGrath SP (1998) Toxicity of heavy metals to microorganisms and microbial processes in agricultural soils: A review. Soil Biol Bioch 30:1389-1414 Keeney DR, Nelson DW (1982) Nitrogen-inorganic forms. In: Page AL et al (eds) Methods of soil analysis, part 2, Chemical and microbial properties, 2 ed. ASA-SSSA, Madison, WI, USA Klute A (1986) Water retention: laboratory methods. In: Klute A (ed) Methods of soil analysis, part 1, Physical and mineralogical methods, 2 ed. ASA-SSSA, Madison, WI, USA Nannipieri P (1994) The potential use of soil enzymes as indicators of productivity, sustainability and pollution. In: Pankhurst CE, Doube BM, Gupta VVSR, Grace PR (eds) Soil biota: management in sustainable farming systems. CSIRO , East Melbourne, p 238-244

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Olsen SR, Sommers LE (1982) Nitrogen-inorganic forms. In: Page AL et al (eds) Methods of soil analysis, part 2, Chemical and microbial properties, 2 ed. ASA-SSSA, Madison, WI, USA Sørensen J (1978) Denitrification rate in a marine sediment as measured by the acetylene inhibition technique. Apl Env Micr 36:139-143 Trasar-Cepeda C, Leirós MC, Gil-Sostres F, Seoane S (1998) Towards a biochemical quality index for soils: an expression relating several biological and biochemical properties. Biol Fert Soil 26:100-106 Yakovchenko VI, Sikora LJ, Kauffmann DD (1996) A biologically based indicator of soil quality. Biol Fertl Soil 21:245-251 Young PJ, Pollard S, Crowcroft PL (1997) Overview: content, calculation risk and using consultants. In: Hester RE, Harrison RM (eds) Contaminated land and its reclamation, The Royal Society of Chemistry, Cambridge, p 1-24

CONTENTSPRÓLOGOPREFACECHAPTER 1. ENVIRONMENTAL IMPACT ASSESSMENT1.1. TERRESTRIAL ECOSYSTEM1.2. AQUATIC ECOSYSTEM1.2.1. FLUVIAL ECOSYSTEM1.2.2. ESTUARINE ECOSYSTEM1.3. SOCIO-ECONOMIC IMPACTCHAPTER 2. ENVIRONMENTAL RISK ASSESSMENTCHAPTER 3. INTEGRAL MANAGEMENT OF THE ECOSYSTEMCHAPTER 4. REMARKS