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Agrostis castellana and Agrostis delicatula on heavy metal and arsenic enriched sites in NE Portugal
the Science of the Total Environment i.to iS, E,wU~m,~l ~ a i u h ~ t t * ~
ELSEVIER
~th ~
The Science of the Total Environment 145 (1994) 103-109
Agrostis castellana and Agrostis delicatula on heavy metal and arsenic enriched sites in NE Portugal T. De Koe Department of Biology Universidade de Trds-os-Montes e Alto Douro, Quinta dos Prados, 5000 Vila Real, Portugal (Received 10 November 1992: accepted 7 December 1993)
Abstract Heavy metals and As have been analysed in soils of 15 mine sites in NE Portugal and in plants of Agrostis castellana and Agrostis delicatula growing on these sites. Gold mine spoils contain high levels of As (17 000 mg kg -I) and heavy metals (2200 mg kg -t Pb, 1800 mg kg -t Mn and 520 mg kg -~ Zn). Tungsten mine spoils contain high levels of Cu (1800 mg kg -r) and Cd (60 mg kg-I). Accumulation of heavy metals and arsenic is species specific and distribution within a plant specific to plant parts. A. castellana accumulates As and Zn up to 1900 and 4600 mg kg -~ in senescent shoots, with Cu and Cd up to 1300 and 60 mg kg -~ in roots. A. delicatula roots contain up to 1400 mg kg -j Mn and 1100 mg kg -I Pb. The importance of both Agrostis species in revegetation experiments is indicated.
Key words: Agrostis castellana; Agrostis delicatula; Arsenic
I. Introduction Agrostis species (A. can&a, ,4. capillaris, A. stolonifera and A. gigantea) are known colonisers of mine spoils in Western and Central Europe (Ernst, 1990). In NE Portugal, Agrostis castellana and Agrostis delicatula take their place, often as the only colonisers, growing in small tufts on the otherwise barren spoil heaps (De Koe et al., 1991; De Koe, 1991). Mineral exploration in NE Portugal has taken place at least since the Roman times. Gold, iron, lead, tin and tungsten mines are found in areas of contact between metamorphosed rocks (generally schists of Precambrian or lower Paleozoic age) and
the igneous granites. Generally the ore has been extracted in deep mines, producing large amounts of waste rock and tailings. Although all the mines, except the Jales gold mine, are closed, erosion of the, mainly barren, spoil heaps by wind and water results in permanent pollution of the surrounding terrestrial and aquatic ecosystems. The establishment of vegetation is usually part of reclamation programmes. Revegetation of these harsh environments requires a thorough knowledge of the most polluting and toxic elements in the soil, as well as knowledge about species that are able to colonize the mine spoils and evolve tolerant genotypes. Agrostis species have been used in revegetation programmes in Western Europe.
0048-9697/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved. SSDI 0048-9697(93)03659-P
104
T. De Koe/Sci. Total Environ. 145 (1994) 103-109
Some metal tolerant cultivars of Agrostis capillaris are available on a commercial scale (Williamson and Johnson, 1981). Agrostis castellana and Agrostis delicatula are of potential importance in revegetation experiments in SE Europe. 2. Materials and methods
Samples of Agrost& castellana Boiss et Reut., Agrost& delicatula Pouret ex Lapeyr and soils have been collected on 15 mine sites (Fig. 1). The collected plants have been thoroughly washed in
demineralised water and separated into roots, senescent and living shoot material. The samples have been dried at 70°C for 48 h. After wet digestion of the organic matter in 100 mg homogenized samples using 10 ml HNO3/HCIO4 (10:1 v/v), the concentrations of As, Pb, Zn, Cu, Cd, Mn, Fe, Ni and AI have been determined by atomic absorption spectrometry using a Perkin-Elmer AAS, and with a HMS-10 hydride system for As. The soil samples, collected from barren sites as well as adherent to the plant roots, have been dried at 40°C for 48 h, passed through a 2 mm mesh
N
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• ....
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•
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• :: ""]':'.W:";-'.
[--]
Lower poleozoic rocks
~
Granite Basic and ultra-basic
~
P r ¢ - c a m b r i o n rocks Mines
rocks
Fig. 1. Localization of gold mines (1, Jales; 2, Tr~s-Minas; 3, Freixeda; 4, Penedono), iron mines (5, Moncorvo; 6, Mar~[o), tin mines (7, Portelo; 8, Ervedosa; 9, Code¢o; 10, Vila Cova), tungsten mines (11, Adoria; 12, Vale das Gatas; 13, Ifanes), tin/tungsten mines (14, Ribeira; 15, Paredes) and main geological features of the study area (adapted from Servi¢os Geol6gicos 1960).
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Fig. 2. Total Cu, Mn, Pb, Zn and As content (mg kg-l), its ammonium acetate and calcium lactate extractable, and water soluble fractions of soil samples form the gold mines Jales (J), Tr6s-Minas (TM), Freixeda (F) and Penedono (Pe), the iron mines Moncorvo (M) and MarCo (Ma), the tin mines Portelo (Po), Ervedosa (E), Codeqo (C) and Vila Cova (VC), the tungsten mines Adoria (A), Vale das Gatas (G) and Ifanes (I), and the tin/tungsten mines Ribeira (R) and Paredes (P).
T. De Koe /Sci. Total Environ. 145 (1994) 103-109
106
wet digestion of the organic matter of 1 g samples by HCI/HNO3 (3:1 v/v), after incubating for 2 h with 6N HCI or by HF, HC104, H2SO4 and HCI application according to Jackson (1958).
plastic sieve and homogenized by grinding for 30 min in a mortar grinder. The water soluble and bioavailable fractions have been analysed as well as the total concentration using the same elements as for the plants. The water soluble fraction, supposed to be directly available to the plants, is measured in the filtrate after extracting 5 g dry soil with 50 ml demineralised water during 2 h under constant rotation in polyethylene flasks, pH is then measured in this filtrate. The bioavailable fraction of the elements is simulated by extraction with ammonium acetate, measured after incubating 5 g dry soil in 50 ml 1 M NH4Ac (pH = 5 with acetic acid) for 2 h. An indication of the bioavailability of As is given by its concentration in the extract of 5 g dry soil in 50 ml calcium lactate (Steubing, 1965) under the same conditions. Total concentrations were determined after
3. Results
3.1. Soil samples Very high total concentrations of As (Fig. 2) have been found in the soil samples of the Jales, Freixeda and Penedono gold mines (17 000, 12 000 and 2800 mg kg -l, respectively) and the Vale das Gatas tungsten mine (5200 mg kg-l). On these sites up to 90 mg kg -l As is extractable using calcium lactate. On all other sites total As varies from 2 to 1100 mg kg -I with calcium lactate extractable concentrations ranging from <1 to 10 mg kg -t As.
Table 1 Arsenic and heavy metals (mg kg -j) in Agrostis castellana from mine spoil heaps (R, roots; S, shoot; SS, senescent shoot; LS, living shoot) Mines
Organ
As
Pb
Zn
Cu
Cd
Mn
Fe
AI
Ni
Au
R SS LS R SS LS R S
1000 1900 170 940 170 580 20 0
300 580 80 210 50 170 20 20
2600 4600 2000 500 500 550 110 50
110 110 30 40 10 10 10 10
50 40 10 10 10 0 0
430 870 500 230 500 350 160 270
3300 3200 1800 3200 970 930 49 000 4000
-380 50 70 -20 350 70
30 20 20 10 -20 20 3
R S R SS LS R
.
50 400 100 70 300
10 320 80 30 100
1 10 1 1 3
560 910 470 540 190
12 000 3700 1300 430 1900
-150 110 30 10 120
-10 60 10 10 20
20 10 10 10 10 10 100 50
2 0 0 0 I 1 3 3
440 230 300 330 150 380 40 130
930 3700 710 590 4500 1700 810 1400
50 150 30 20 140 40 60 30
10 10 3 4 30 10 20 10
420 280 130 370 510
9600 1100 2400 1400
-310 60 170 I10
10 3 10 10
Jales Au
Freixeda Fe
Moncorvo Fe
Marffo Sn
Portelo Sn
Ervedosa Sn
Codeqo Sn
VilaCova W
Adoria W
Gatas W
Ifanes Sn/W
Paredes
S R SS LS R S R S R S R S R S
40 40 10 3 20
.
. 20 20 10 20 20
10 10 1 0 10 2 100 140
20 10 0 10 30 10 430 530
190 130 90 70 120 80 190 190
50 220 60 70 40
. 70 40 20 20 20
. 400 1100 420 280 280
.
.
. 60 1300 190 190 80
. 4 60 10 4 4
T. De Koe/Sci. Total Environ. 145 (1994) 103-109
107
mine and the Ribeira and Paredes tin/tungsten mines (1800, 900 and 380 mg kg -I Cu, respectively), with ammonium acetate extractable fractions of 150 mg kg -I Cu at Ifanes decreasing to 50 mg kg -l Cu at Paredes. On the other sites total Cu concentrations are lower, ranging from 10 to 100 mg kg -l, with ammonium acetate extractable fractions from < 1 to 10 mg kg -~ Cu. Total Cd concentrations are generally <1 mg kg -1, but 60 mg kg -l Cd is found at the Ifanes tungsten mine and 10 mg kg -l Cd at the Freixeda gold mine and the Ribeira and Paredes tin/tungsten mines. Total Ni concentrations are < 1 mg kg -l on all sites. Total Fe concentrations are highest (150 000 mg kg -I) at the Moncorvo and MarCo iron mines, and ranging on the other sites from 12 000 to 50 000 mg kg -l Fe. Total AI concentrations are highest (21 000 mg kg -1) at the Jales gold mine and ranging from 36 000 to 76 000 mg kg -l A1 on the other sites.
The spoil heaps at the gold mines also exhibit the highest total concentrations of Pb, Mn and Zn (2200 mg kg -1 Pb at Freixeda, 1800 mg kg -l Mn at Tr~s-Minas and 520 mg kg -I Zn at Jales). Total Pb concentrations are also high at the Jales gold mine and the Adoria tungsten mine (1000 and 940 mg kg -~ Pb respectively, with ammonium acetate extractable concentrations of 20 and 30 mg kg -I Pb). On all other sites total Pb ranges from 10 to 210 mg kg -I, with ammonium acetate extractable concentrations from < 1 to 20 mg kg-I Pb. Total Mn concentrations are low on the other sites, ranging from 10 to 1100 mg kg -1, with ammonium acetate extractable fractions ranging from < 1 to 50 mg kg -l Mn. Total Zn concentrations on the other sites range from 50 to 300 mg kg -j, with ammonium acetate concentrations from < 1 to 230 mg kg -l Zn. Highest total Cu concentrations are found in the NE part of the research area at the Ifanes tungsten
Table 2 Arsenic and heavy metals (mg kg -I) in Agrostis delicatula from mine spoil heaps (R, roots; S, shoot; SS, senescent shoot; LS, living shoot) Mines
Organ
As
Pb
Zn
Au Jales Au Freixeda Fe
R S R SS LS R
1800 300 650 310 60 30
650 200 380 70 40 20
580 330 400 850 250 100
Moncorvo Fe MarCo Sn
S R S R
10
20
40
Portelo
SS LS R S R SS LS R S R S R S R S
Sn Ervedosa Sn Code~o Sn Vila Cova W Adoria W Gatas Sn/W Paredes
Cu
Cd
Mn
Fe
AI
Ni
50 20 30 20 40 10
30 10 ---0
1400 1200 100 450 500 280
6000 1000 2800 1200 120 85000
---
20
4
340
46000
50 70
20 20
50 100
10 120
0 . 0 0
100 30 250 120 10 1 0 20 10 70 70
20 20 50 20 10 0 10 20 20 I100 420
80 70 300 190 130 90 70 60 60 370 120
130 40 60 30 10 4 10 20 10 120 40
.
.
.
. 160
.
. 140
. 270
.
. 880
. 20
.
.
70
4
.
570 100
2000 16000
240 260
5 10
0 1 0 0 0 0 0 0 0 3 1
580 790 80 150 230 300 330 140 340 100 110
11000 1700 5100 1200 6500 1100 950 12000 4000 9300 1100
170 40 160 70 220 70 50 280 150 70 30
10 I0 10 10 10 1 10 20 10 30 4
20
390
3
270
. 360
. 140
.
II000
-20
.
.
.
.
. 290
6700
300
4
108
3.2. Plant samples The grasses reflect the high concentrations in the soil, particularly in their root and senescent shoot tissues (Tables 1 and 2). Highest values of As, Zn and Mn are found in grasses from the Jales gold mine: 1900 mg kg -l As and 4600 mg kg -1 Zn in Agrostis castellana senescent shoots and 1400 mg kg -l Mn in A. delicatula roots. As in roots from A. castellana at the nongoldmine spoils ranges from 10 to 220 mg kg -l, and in A. delicatula from 2 to 70 mg kg -l As. High values of Zn (1100 mg kg -l) are also found in the roots of A. castellana from the Ifanes tungsten mine. At the other mines Zn in A. castellana roots ranges from 110 to 400 mg kg -l, and for A. delicatula these values are 60-150 mg kg -l. Mn in A. castellana roots ranges from 40 to 910 mg kg -l at the non-goldmine spoils, and in A. delicatula roots from 80 to 250 mg kg -1. Generally Mn concentrations are higher in the living shoots than the senescent parts. Agrostis castellana roots from the Ifanes tungsten mine exhibit the highest Cu (1300 mg kg -1) and Cd (60 mg kg -1) values. Cu in A. castellana roots at the other mines ranges from 10 to 320 mg kg -1, and for A. delieatula these values are 10-120 mg kg -I Cu. Cd is also high in A. eastellana roots at the gold mines (Jales: 50 mg kg-I), but <1 mg kg -l on the other sites. A. delicatula and A. castellana roots of the Adoria tungsten mine have the highest Pb concentrations (1100 and 430 mg kg -l, respectively). The gold mine sites also show high Pb values in A. delicatula roots (Jales: 650 mg kg -l, Freixeda: 380 mg kg-l). A. castellana roots always have lower Pb levels than A. delicatula. 4. Discussion The soils at the mine sites in NE Portugal are characterized by a site specific excess of mineral elements: As at the gold mines and the Vale das Gatas tungsten mine spoil heaps, sometimes cooccurs with high concentrations of Pb (Freixeda), Mn (Tr~s Minas) or Zn (Jales); Cu is present in the wastes of some tungsten (Ifanes) and tin/tungsten mines (Ribeira). These metal concentrations are comparable with those reported for other mine
T. De Koe/Sci. Total Environ. 145 (1994) 103-109
sites in Europe (Ernst, 1974), or are sometimes low as in the spoils of the iron mines. The availability of metals and As in the spoils, in part due to a low pH (De Koe et al., 1991), results in high concentrations in the various plant parts compared with plants growing under normal soil conditions. Agrostis castellana and A. delicatula from the gold mines reach As values (roots: 1000 and 1800 mg kg -1, green shoots: 170 and 300 mg kg -l, respectively) in the range reported by Porter and Peterson (1977) for other Agrostis species on mine wastes in the UK. However, it is not clear which plant parts they analysed so a precise comparison is not possible. The 1300 mg kg -l Cu in A. castellana roots on the high copper sites is in the range reported for A. gigantea (Hogan et al., 1977) from a mine waste site in Sudbury. On the Jales gold mine spoils, A. castellana shows Zn concentrations of 2600 mg kg -l in the roots and 2000 mg kg -j in the green shoots, values that are comparable to those found by Otte (1991) in A. stolonifera on polluted Rhine estuary soils. The other elements analysed reach higher concentrations in A. castellana and A. delicatula than reported for other Agrostis species from contaminated sites: A. gigantea roots with 375 mg kg -l Mn, and shoots with 403 mg kg -j Mn (Hogan et al., 1977); A. capillaris plants with 129 mg kg -l Pb (Simon, 1977); A. stolonifera roots with 14 mg kg -I Cd, and shoots with 2 mg kg-~Cd (Otte 1991). The establishment of a vegetation cover on mine spoil heaps encounters several problems (e.g. Bradshaw and Chadwick, 1980). The low water and nutrient content of the spoils and high heavy metal and arsenic availability are the main problems to overcome. Infection with VAM fungi can improve the access of the plant to nutrients and water (Smith and Gianazzi-Pearson, 1988). However, Ietswaart et al., (1992) found only a small impact of VAM infection on the nutrient concentration of Agrostis eapillaris under field conditions. Once adequate physical and chemical conditions of the waste are established, the use of an appropriate seed mixture is very important. Species that are able to evolve tolerance to heavy metals and As, or even co-tolerance to several contaminants,
T. De Koe / Sci. Total Environ. 145 (1994) 103-109
and at the same time have low nutrient demands are to be preferred. For some decades, Agrostis species are known to develop tolerance to heavy metals (Wu and Antonovics, 1975) and As (Porter and Peterson, 1977). Metal resistant genotypes are known from several Agrostis species (A. canina, A. capillaris, A. stolonifera and A. gigantea, Ernst, 1990). Although several Agrostis species are found in Portugal, among them A. canina, A. capillaris and A. stolonifera, the mine wastes in NE Portugal are mainly colonized by Agrostis castellana and A. delicatula, species able to establish themselves under the extreme ecological circumstances. Recent research (De Koe and Jaques, 1992) proves the existence of As tolerant genotypes of Agrostis castellana and A. delicatula. Arsenic tolerance is shown to be an inherited characteristic in Agrostis capillaris (Watkins and Macnair, 1991). The development of tolerant genotypes of Agrostis castellana and A. delicatula to other contaminants present in the spoil heaps (Zn, Cu, Pb and Mn) is likely (De Koe, unpublished data). In conclusion, Agrostis castellana and A. delicatula are of potential importance in revegetation programmes of mine spoils, and of arsenic enriched spoils in particular, in south-west Europe. 5. References Bradshaw, A.D. and M.J. Chadwick, 1980. The restoration of land. The ecology and reclamation of derelict and degraded land. Blackwell, Oxford. De Koe, T., 1991. Arsenic in water, sediment and vegetation of the Jales gold mine, North Portugal. In: J. Rozema and J.A.C. Verkleij (Eds.), Ecological Responses to Environmental Stresses, Kluwer, Dordrecht, Ch. 5, p. 311. De Koe, T., M.A. Beek, M.S. Haarsma, W.H.O. Ernst, 1991.
109 Heavy metals and arsenic in grasses and soils of mine spoils in north east Portugal, with particular reference to some Portuguese goldmines. In: B. Nath (Ed.), Environmental Pollution, Vol. 1, Proceedings of an International Conference, ICEP-I, 373-380. De Koe, Y. and N.M.M. Jaques, 1993. Arsenate tolerance in Agrostis castellana and Agrostis delicatula. Plant Soil, 151: 185-191. Ernst, W.H.O., 1990. Mine Vegetation in Europe. In: A.J. Shaw (Ed.), Heavy Metal Tolerance in Plants: Evolutionary Aspects, CRC Press, Boca Raton, FL, Ch. 3, p. 355. Ernst, W.H.O., 1974. Schwermetallvegetation der Erde. Fisher, Stuttgart. Hogan, G.D., G.M. Courtin and W.E. Rauser, 1977. Copper tolerance in clones of Agrostis gigantea from a mine waste site. Can. J. Bot., 55: 1043-1050. letswaart, J.H., W.A.J. Griffioen, W.H.O. Ernst, 1992. Seasonality of VAM infection in three populations of Agrostis capillaris (Gramineae) on soil with or without heavy metal enrichment. Plant Soil, 139: 67-73. Jackson, M.L., 1958. Soil chemical analysis. Prentice-Hall, Englewood Cliffs, NJ. Otte, M.L., 1991. Heavy Metals and Arsenic in Vegetation of Salt Marshes and Floodplains. PhD thesis Vrije Universiteit, Amsterdam, p. 188. Porter, E.K. and P.J. Peterson, 1977. Arsenic tolerance in grasses growing on mine waste. Environ. Pollut., 14: 255-265. Simon, R.A., 1977. Cadmium tolerance in populations of Agrostis tenuis and Festuca ovina. Nature 265: 328-330. Smith, S.E. and V. Gianazzi-Pearson, 1988. Physiological interactions between symbionts in vesicular-arbuscular mycorrhizal plants. Annu. Rev. Plant Physiol. Plant Mol. Biol., 39: 221-244. Steubing, L., 1965. Pflanzen6kologische Praktikum: Methoden und Ger/ite zur Bestimmung wichtiger Standortsfaktoren. Parey, Berlin. Williamson, A. and M.S. Johnson, 1981. Reclamation of Metalliferous Mine Wastes. In: N.W. Lepp (Ed.), Effect of Heavy Metal Pollution on Plants, Vol. 2, Applied Science Publishers, London: 185-212. Watkins, A.J. and M.R. Macnair, 1991. Genetics of arsenic tolerance in Agrostis capillaris L. Heredity, 66: 47-54. Wu, L. and J. Antonovics, 1975. Zinc and copper uptake by Agrostis stolonifera, tolerant to both zinc and copper. N. Phytol., 75: 231-237.
ELSEVIER
~th ~
The Science of the Total Environment 145 (1994) 103-109
Agrostis castellana and Agrostis delicatula on heavy metal and arsenic enriched sites in NE Portugal T. De Koe Department of Biology Universidade de Trds-os-Montes e Alto Douro, Quinta dos Prados, 5000 Vila Real, Portugal (Received 10 November 1992: accepted 7 December 1993)
Abstract Heavy metals and As have been analysed in soils of 15 mine sites in NE Portugal and in plants of Agrostis castellana and Agrostis delicatula growing on these sites. Gold mine spoils contain high levels of As (17 000 mg kg -I) and heavy metals (2200 mg kg -t Pb, 1800 mg kg -t Mn and 520 mg kg -~ Zn). Tungsten mine spoils contain high levels of Cu (1800 mg kg -r) and Cd (60 mg kg-I). Accumulation of heavy metals and arsenic is species specific and distribution within a plant specific to plant parts. A. castellana accumulates As and Zn up to 1900 and 4600 mg kg -~ in senescent shoots, with Cu and Cd up to 1300 and 60 mg kg -~ in roots. A. delicatula roots contain up to 1400 mg kg -j Mn and 1100 mg kg -I Pb. The importance of both Agrostis species in revegetation experiments is indicated.
Key words: Agrostis castellana; Agrostis delicatula; Arsenic
I. Introduction Agrostis species (A. can&a, ,4. capillaris, A. stolonifera and A. gigantea) are known colonisers of mine spoils in Western and Central Europe (Ernst, 1990). In NE Portugal, Agrostis castellana and Agrostis delicatula take their place, often as the only colonisers, growing in small tufts on the otherwise barren spoil heaps (De Koe et al., 1991; De Koe, 1991). Mineral exploration in NE Portugal has taken place at least since the Roman times. Gold, iron, lead, tin and tungsten mines are found in areas of contact between metamorphosed rocks (generally schists of Precambrian or lower Paleozoic age) and
the igneous granites. Generally the ore has been extracted in deep mines, producing large amounts of waste rock and tailings. Although all the mines, except the Jales gold mine, are closed, erosion of the, mainly barren, spoil heaps by wind and water results in permanent pollution of the surrounding terrestrial and aquatic ecosystems. The establishment of vegetation is usually part of reclamation programmes. Revegetation of these harsh environments requires a thorough knowledge of the most polluting and toxic elements in the soil, as well as knowledge about species that are able to colonize the mine spoils and evolve tolerant genotypes. Agrostis species have been used in revegetation programmes in Western Europe.
0048-9697/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved. SSDI 0048-9697(93)03659-P
104
T. De Koe/Sci. Total Environ. 145 (1994) 103-109
Some metal tolerant cultivars of Agrostis capillaris are available on a commercial scale (Williamson and Johnson, 1981). Agrostis castellana and Agrostis delicatula are of potential importance in revegetation experiments in SE Europe. 2. Materials and methods
Samples of Agrost& castellana Boiss et Reut., Agrost& delicatula Pouret ex Lapeyr and soils have been collected on 15 mine sites (Fig. 1). The collected plants have been thoroughly washed in
demineralised water and separated into roots, senescent and living shoot material. The samples have been dried at 70°C for 48 h. After wet digestion of the organic matter in 100 mg homogenized samples using 10 ml HNO3/HCIO4 (10:1 v/v), the concentrations of As, Pb, Zn, Cu, Cd, Mn, Fe, Ni and AI have been determined by atomic absorption spectrometry using a Perkin-Elmer AAS, and with a HMS-10 hydride system for As. The soil samples, collected from barren sites as well as adherent to the plant roots, have been dried at 40°C for 48 h, passed through a 2 mm mesh
N
//
I i
-.....-. "'
• ....
~""
"'~'L',~"-x, 2
•
_ .:::."
• :: ""]':'.W:";-'.
[--]
Lower poleozoic rocks
~
Granite Basic and ultra-basic
~
P r ¢ - c a m b r i o n rocks Mines
rocks
Fig. 1. Localization of gold mines (1, Jales; 2, Tr~s-Minas; 3, Freixeda; 4, Penedono), iron mines (5, Moncorvo; 6, Mar~[o), tin mines (7, Portelo; 8, Ervedosa; 9, Code¢o; 10, Vila Cova), tungsten mines (11, Adoria; 12, Vale das Gatas; 13, Ifanes), tin/tungsten mines (14, Ribeira; 15, Paredes) and main geological features of the study area (adapted from Servi¢os Geol6gicos 1960).
105
7". De Koe/Sci. Total Environ. 145 (1994) 103-109
lzo -¢'1
c u zooo -, - ~
2ooo ~"F
$0
I
60
1000 -
ZO
1000
"
o
:
200
o-! 3000-
]I~4MI~PoE CYCG
As
III I I II / I II I J
/I /ill.
o . . . . . . . . . . . . TMMIdLPoE
CYCA
'
I R P
:
600
I R P.
1200 - ~
~]II zooJII 1 II
ol
J ' I M F MMb, PoE C Y C A G l R P
20000 -
As J
Ill/ " Ilia Il ~il O-
~ d
i
~
[] Nl-~Acetaleexlnct~blefnction I~ C~LIctal:e e~dnctablefnction [ ] Totolconcentr~ion
F PeG
Fig. 2. Total Cu, Mn, Pb, Zn and As content (mg kg-l), its ammonium acetate and calcium lactate extractable, and water soluble fractions of soil samples form the gold mines Jales (J), Tr6s-Minas (TM), Freixeda (F) and Penedono (Pe), the iron mines Moncorvo (M) and MarCo (Ma), the tin mines Portelo (Po), Ervedosa (E), Codeqo (C) and Vila Cova (VC), the tungsten mines Adoria (A), Vale das Gatas (G) and Ifanes (I), and the tin/tungsten mines Ribeira (R) and Paredes (P).
T. De Koe /Sci. Total Environ. 145 (1994) 103-109
106
wet digestion of the organic matter of 1 g samples by HCI/HNO3 (3:1 v/v), after incubating for 2 h with 6N HCI or by HF, HC104, H2SO4 and HCI application according to Jackson (1958).
plastic sieve and homogenized by grinding for 30 min in a mortar grinder. The water soluble and bioavailable fractions have been analysed as well as the total concentration using the same elements as for the plants. The water soluble fraction, supposed to be directly available to the plants, is measured in the filtrate after extracting 5 g dry soil with 50 ml demineralised water during 2 h under constant rotation in polyethylene flasks, pH is then measured in this filtrate. The bioavailable fraction of the elements is simulated by extraction with ammonium acetate, measured after incubating 5 g dry soil in 50 ml 1 M NH4Ac (pH = 5 with acetic acid) for 2 h. An indication of the bioavailability of As is given by its concentration in the extract of 5 g dry soil in 50 ml calcium lactate (Steubing, 1965) under the same conditions. Total concentrations were determined after
3. Results
3.1. Soil samples Very high total concentrations of As (Fig. 2) have been found in the soil samples of the Jales, Freixeda and Penedono gold mines (17 000, 12 000 and 2800 mg kg -l, respectively) and the Vale das Gatas tungsten mine (5200 mg kg-l). On these sites up to 90 mg kg -l As is extractable using calcium lactate. On all other sites total As varies from 2 to 1100 mg kg -I with calcium lactate extractable concentrations ranging from <1 to 10 mg kg -t As.
Table 1 Arsenic and heavy metals (mg kg -j) in Agrostis castellana from mine spoil heaps (R, roots; S, shoot; SS, senescent shoot; LS, living shoot) Mines
Organ
As
Pb
Zn
Cu
Cd
Mn
Fe
AI
Ni
Au
R SS LS R SS LS R S
1000 1900 170 940 170 580 20 0
300 580 80 210 50 170 20 20
2600 4600 2000 500 500 550 110 50
110 110 30 40 10 10 10 10
50 40 10 10 10 0 0
430 870 500 230 500 350 160 270
3300 3200 1800 3200 970 930 49 000 4000
-380 50 70 -20 350 70
30 20 20 10 -20 20 3
R S R SS LS R
.
50 400 100 70 300
10 320 80 30 100
1 10 1 1 3
560 910 470 540 190
12 000 3700 1300 430 1900
-150 110 30 10 120
-10 60 10 10 20
20 10 10 10 10 10 100 50
2 0 0 0 I 1 3 3
440 230 300 330 150 380 40 130
930 3700 710 590 4500 1700 810 1400
50 150 30 20 140 40 60 30
10 10 3 4 30 10 20 10
420 280 130 370 510
9600 1100 2400 1400
-310 60 170 I10
10 3 10 10
Jales Au
Freixeda Fe
Moncorvo Fe
Marffo Sn
Portelo Sn
Ervedosa Sn
Codeqo Sn
VilaCova W
Adoria W
Gatas W
Ifanes Sn/W
Paredes
S R SS LS R S R S R S R S R S
40 40 10 3 20
.
. 20 20 10 20 20
10 10 1 0 10 2 100 140
20 10 0 10 30 10 430 530
190 130 90 70 120 80 190 190
50 220 60 70 40
. 70 40 20 20 20
. 400 1100 420 280 280
.
.
. 60 1300 190 190 80
. 4 60 10 4 4
T. De Koe/Sci. Total Environ. 145 (1994) 103-109
107
mine and the Ribeira and Paredes tin/tungsten mines (1800, 900 and 380 mg kg -I Cu, respectively), with ammonium acetate extractable fractions of 150 mg kg -I Cu at Ifanes decreasing to 50 mg kg -l Cu at Paredes. On the other sites total Cu concentrations are lower, ranging from 10 to 100 mg kg -l, with ammonium acetate extractable fractions from < 1 to 10 mg kg -~ Cu. Total Cd concentrations are generally <1 mg kg -1, but 60 mg kg -l Cd is found at the Ifanes tungsten mine and 10 mg kg -l Cd at the Freixeda gold mine and the Ribeira and Paredes tin/tungsten mines. Total Ni concentrations are < 1 mg kg -l on all sites. Total Fe concentrations are highest (150 000 mg kg -I) at the Moncorvo and MarCo iron mines, and ranging on the other sites from 12 000 to 50 000 mg kg -l Fe. Total AI concentrations are highest (21 000 mg kg -1) at the Jales gold mine and ranging from 36 000 to 76 000 mg kg -l A1 on the other sites.
The spoil heaps at the gold mines also exhibit the highest total concentrations of Pb, Mn and Zn (2200 mg kg -1 Pb at Freixeda, 1800 mg kg -l Mn at Tr~s-Minas and 520 mg kg -I Zn at Jales). Total Pb concentrations are also high at the Jales gold mine and the Adoria tungsten mine (1000 and 940 mg kg -~ Pb respectively, with ammonium acetate extractable concentrations of 20 and 30 mg kg -I Pb). On all other sites total Pb ranges from 10 to 210 mg kg -I, with ammonium acetate extractable concentrations from < 1 to 20 mg kg-I Pb. Total Mn concentrations are low on the other sites, ranging from 10 to 1100 mg kg -1, with ammonium acetate extractable fractions ranging from < 1 to 50 mg kg -l Mn. Total Zn concentrations on the other sites range from 50 to 300 mg kg -j, with ammonium acetate concentrations from < 1 to 230 mg kg -l Zn. Highest total Cu concentrations are found in the NE part of the research area at the Ifanes tungsten
Table 2 Arsenic and heavy metals (mg kg -I) in Agrostis delicatula from mine spoil heaps (R, roots; S, shoot; SS, senescent shoot; LS, living shoot) Mines
Organ
As
Pb
Zn
Au Jales Au Freixeda Fe
R S R SS LS R
1800 300 650 310 60 30
650 200 380 70 40 20
580 330 400 850 250 100
Moncorvo Fe MarCo Sn
S R S R
10
20
40
Portelo
SS LS R S R SS LS R S R S R S R S
Sn Ervedosa Sn Code~o Sn Vila Cova W Adoria W Gatas Sn/W Paredes
Cu
Cd
Mn
Fe
AI
Ni
50 20 30 20 40 10
30 10 ---0
1400 1200 100 450 500 280
6000 1000 2800 1200 120 85000
---
20
4
340
46000
50 70
20 20
50 100
10 120
0 . 0 0
100 30 250 120 10 1 0 20 10 70 70
20 20 50 20 10 0 10 20 20 I100 420
80 70 300 190 130 90 70 60 60 370 120
130 40 60 30 10 4 10 20 10 120 40
.
.
.
. 160
.
. 140
. 270
.
. 880
. 20
.
.
70
4
.
570 100
2000 16000
240 260
5 10
0 1 0 0 0 0 0 0 0 3 1
580 790 80 150 230 300 330 140 340 100 110
11000 1700 5100 1200 6500 1100 950 12000 4000 9300 1100
170 40 160 70 220 70 50 280 150 70 30
10 I0 10 10 10 1 10 20 10 30 4
20
390
3
270
. 360
. 140
.
II000
-20
.
.
.
.
. 290
6700
300
4
108
3.2. Plant samples The grasses reflect the high concentrations in the soil, particularly in their root and senescent shoot tissues (Tables 1 and 2). Highest values of As, Zn and Mn are found in grasses from the Jales gold mine: 1900 mg kg -l As and 4600 mg kg -1 Zn in Agrostis castellana senescent shoots and 1400 mg kg -l Mn in A. delicatula roots. As in roots from A. castellana at the nongoldmine spoils ranges from 10 to 220 mg kg -l, and in A. delicatula from 2 to 70 mg kg -l As. High values of Zn (1100 mg kg -l) are also found in the roots of A. castellana from the Ifanes tungsten mine. At the other mines Zn in A. castellana roots ranges from 110 to 400 mg kg -l, and for A. delicatula these values are 60-150 mg kg -l. Mn in A. castellana roots ranges from 40 to 910 mg kg -l at the non-goldmine spoils, and in A. delicatula roots from 80 to 250 mg kg -1. Generally Mn concentrations are higher in the living shoots than the senescent parts. Agrostis castellana roots from the Ifanes tungsten mine exhibit the highest Cu (1300 mg kg -1) and Cd (60 mg kg -1) values. Cu in A. castellana roots at the other mines ranges from 10 to 320 mg kg -1, and for A. delieatula these values are 10-120 mg kg -I Cu. Cd is also high in A. eastellana roots at the gold mines (Jales: 50 mg kg-I), but <1 mg kg -l on the other sites. A. delicatula and A. castellana roots of the Adoria tungsten mine have the highest Pb concentrations (1100 and 430 mg kg -l, respectively). The gold mine sites also show high Pb values in A. delicatula roots (Jales: 650 mg kg -l, Freixeda: 380 mg kg-l). A. castellana roots always have lower Pb levels than A. delicatula. 4. Discussion The soils at the mine sites in NE Portugal are characterized by a site specific excess of mineral elements: As at the gold mines and the Vale das Gatas tungsten mine spoil heaps, sometimes cooccurs with high concentrations of Pb (Freixeda), Mn (Tr~s Minas) or Zn (Jales); Cu is present in the wastes of some tungsten (Ifanes) and tin/tungsten mines (Ribeira). These metal concentrations are comparable with those reported for other mine
T. De Koe/Sci. Total Environ. 145 (1994) 103-109
sites in Europe (Ernst, 1974), or are sometimes low as in the spoils of the iron mines. The availability of metals and As in the spoils, in part due to a low pH (De Koe et al., 1991), results in high concentrations in the various plant parts compared with plants growing under normal soil conditions. Agrostis castellana and A. delicatula from the gold mines reach As values (roots: 1000 and 1800 mg kg -1, green shoots: 170 and 300 mg kg -l, respectively) in the range reported by Porter and Peterson (1977) for other Agrostis species on mine wastes in the UK. However, it is not clear which plant parts they analysed so a precise comparison is not possible. The 1300 mg kg -l Cu in A. castellana roots on the high copper sites is in the range reported for A. gigantea (Hogan et al., 1977) from a mine waste site in Sudbury. On the Jales gold mine spoils, A. castellana shows Zn concentrations of 2600 mg kg -l in the roots and 2000 mg kg -j in the green shoots, values that are comparable to those found by Otte (1991) in A. stolonifera on polluted Rhine estuary soils. The other elements analysed reach higher concentrations in A. castellana and A. delicatula than reported for other Agrostis species from contaminated sites: A. gigantea roots with 375 mg kg -l Mn, and shoots with 403 mg kg -j Mn (Hogan et al., 1977); A. capillaris plants with 129 mg kg -l Pb (Simon, 1977); A. stolonifera roots with 14 mg kg -I Cd, and shoots with 2 mg kg-~Cd (Otte 1991). The establishment of a vegetation cover on mine spoil heaps encounters several problems (e.g. Bradshaw and Chadwick, 1980). The low water and nutrient content of the spoils and high heavy metal and arsenic availability are the main problems to overcome. Infection with VAM fungi can improve the access of the plant to nutrients and water (Smith and Gianazzi-Pearson, 1988). However, Ietswaart et al., (1992) found only a small impact of VAM infection on the nutrient concentration of Agrostis eapillaris under field conditions. Once adequate physical and chemical conditions of the waste are established, the use of an appropriate seed mixture is very important. Species that are able to evolve tolerance to heavy metals and As, or even co-tolerance to several contaminants,
T. De Koe / Sci. Total Environ. 145 (1994) 103-109
and at the same time have low nutrient demands are to be preferred. For some decades, Agrostis species are known to develop tolerance to heavy metals (Wu and Antonovics, 1975) and As (Porter and Peterson, 1977). Metal resistant genotypes are known from several Agrostis species (A. canina, A. capillaris, A. stolonifera and A. gigantea, Ernst, 1990). Although several Agrostis species are found in Portugal, among them A. canina, A. capillaris and A. stolonifera, the mine wastes in NE Portugal are mainly colonized by Agrostis castellana and A. delicatula, species able to establish themselves under the extreme ecological circumstances. Recent research (De Koe and Jaques, 1992) proves the existence of As tolerant genotypes of Agrostis castellana and A. delicatula. Arsenic tolerance is shown to be an inherited characteristic in Agrostis capillaris (Watkins and Macnair, 1991). The development of tolerant genotypes of Agrostis castellana and A. delicatula to other contaminants present in the spoil heaps (Zn, Cu, Pb and Mn) is likely (De Koe, unpublished data). In conclusion, Agrostis castellana and A. delicatula are of potential importance in revegetation programmes of mine spoils, and of arsenic enriched spoils in particular, in south-west Europe. 5. References Bradshaw, A.D. and M.J. Chadwick, 1980. The restoration of land. The ecology and reclamation of derelict and degraded land. Blackwell, Oxford. De Koe, T., 1991. Arsenic in water, sediment and vegetation of the Jales gold mine, North Portugal. In: J. Rozema and J.A.C. Verkleij (Eds.), Ecological Responses to Environmental Stresses, Kluwer, Dordrecht, Ch. 5, p. 311. De Koe, T., M.A. Beek, M.S. Haarsma, W.H.O. Ernst, 1991.
109 Heavy metals and arsenic in grasses and soils of mine spoils in north east Portugal, with particular reference to some Portuguese goldmines. In: B. Nath (Ed.), Environmental Pollution, Vol. 1, Proceedings of an International Conference, ICEP-I, 373-380. De Koe, Y. and N.M.M. Jaques, 1993. Arsenate tolerance in Agrostis castellana and Agrostis delicatula. Plant Soil, 151: 185-191. Ernst, W.H.O., 1990. Mine Vegetation in Europe. In: A.J. Shaw (Ed.), Heavy Metal Tolerance in Plants: Evolutionary Aspects, CRC Press, Boca Raton, FL, Ch. 3, p. 355. Ernst, W.H.O., 1974. Schwermetallvegetation der Erde. Fisher, Stuttgart. Hogan, G.D., G.M. Courtin and W.E. Rauser, 1977. Copper tolerance in clones of Agrostis gigantea from a mine waste site. Can. J. Bot., 55: 1043-1050. letswaart, J.H., W.A.J. Griffioen, W.H.O. Ernst, 1992. Seasonality of VAM infection in three populations of Agrostis capillaris (Gramineae) on soil with or without heavy metal enrichment. Plant Soil, 139: 67-73. Jackson, M.L., 1958. Soil chemical analysis. Prentice-Hall, Englewood Cliffs, NJ. Otte, M.L., 1991. Heavy Metals and Arsenic in Vegetation of Salt Marshes and Floodplains. PhD thesis Vrije Universiteit, Amsterdam, p. 188. Porter, E.K. and P.J. Peterson, 1977. Arsenic tolerance in grasses growing on mine waste. Environ. Pollut., 14: 255-265. Simon, R.A., 1977. Cadmium tolerance in populations of Agrostis tenuis and Festuca ovina. Nature 265: 328-330. Smith, S.E. and V. Gianazzi-Pearson, 1988. Physiological interactions between symbionts in vesicular-arbuscular mycorrhizal plants. Annu. Rev. Plant Physiol. Plant Mol. Biol., 39: 221-244. Steubing, L., 1965. Pflanzen6kologische Praktikum: Methoden und Ger/ite zur Bestimmung wichtiger Standortsfaktoren. Parey, Berlin. Williamson, A. and M.S. Johnson, 1981. Reclamation of Metalliferous Mine Wastes. In: N.W. Lepp (Ed.), Effect of Heavy Metal Pollution on Plants, Vol. 2, Applied Science Publishers, London: 185-212. Watkins, A.J. and M.R. Macnair, 1991. Genetics of arsenic tolerance in Agrostis capillaris L. Heredity, 66: 47-54. Wu, L. and J. Antonovics, 1975. Zinc and copper uptake by Agrostis stolonifera, tolerant to both zinc and copper. N. Phytol., 75: 231-237.