Metal distributions in plants growing on copper mine spoils in Northern Apennines, Italy: the...

Pergamon Applied Geochemhfry, Vol. II, pp. 375-385, 1996

Copyright 0 1996 Elsevier Science Ltd Printed in Great Britain. All rights reserved

0883-2927/96%15.00+0.00

0883-2927(95)00071-2

Metal distributions in plants growing on copper mine spoils in Northern Apennines, Italy: the evaluation of seasonal variations

Enrico Dinelli Dipartimento di Scienze Mineralogiche, Universim di Bologna, P.zza di Porta S. Donato 1; I-40126 Bologna,

Italy

and

Alessandra Lombini Istituto Botanico, Universita di Pavia, V. San Epifanio, 14; I-27100 Pavia, Italy

Abstract-Mine spoil dump material and plants were sampled from the pyrite-chalcopyrite mining area of Vigonzano (Northern Apennines, Italy). Mine spoils have high concentrations of Fe, Mg, Cu, Cr, Co and Ni, and are characterized by moderately to strongly acid environmental conditions. Water leaching tests indicate the following order of extraction: Zn>Cu > Ni > FezCr.

The plants Silene armeriu (Caryophyllaceae) Salk spp. (Salicaceae) and Populus nigra (Salicaceae) were sampled at 4 different growing stages to evaluate seasonal variations in metal concentrations. The results indicate that metal concentrations increase with plant ageing, the highest concentrations being observed in leaves. Low specific diversity in the mine spoil area is the result of severe environmental conditions, but some plants can tolerate high concentrations without sign of stress. Silene armeria is widespread in the Vigonzano mine spoil area and is actually able to tolerate high metal concentrations (up to 504 pg/g Cu, 174 rg/g Zn, 127 pg/g Ni and 138 pg/g Cr), extremely high when compared to those of a S. armeria population from an unpolluted site. The variations of BAC (Biological Accumulation Coefficient) for the plants growing on the Vigonzano mine spoil area indicates that Zn is the element most easily absorbed by plants. An absorption sequence Zn >Co >Cu >Ni > Fe >Cr can be generalized for plants growing on the mine spoil area indicating the importance of soil solution composition in plant absorption. Copyright 0 1996 Elsevier Science Ltd

INTRODUCTION

Excessive concentrations of any trace element may be toxic to plants and animals, sometimes reaching high levels in the food chain. High metal concentrations in the environment may have natural origins such as the weathering of mineralized ores (Rose ef al., 1979) or outcrops of metal rich formations such as black shales (Thornton, 1983). Mining activities generally increase the rate of metal release in to the environment in areas already having anomalous concentrations. Crushing, grinding, washing, smelting and all the other processes used to extract and concentrate metals make elements environmentally labile through normal biogeochemical pathways, to sinks such as sediments, soils or biomass (Davies, 1980, 1983). Mining activities pro- duce large quantities of wastes, composed of barren rocks, ores that cannot be economically extracted, and smelting rejects, that must be disposed in the environment, usually in the surroundings of the mining area. These waste-rock dumps still have high metal concentrations and continue to be a source for metal pollution long after extraction activities ceased (Davies, 1983). There are, however, other factors that should be considered in the evaluation of the environmental conditions of waste-rock dumps such as pH conditions, low soil fertility, low water holding capacity and the presence of steep slopes. All these

factors greatly influence the ability of plants to grow on these areas (Ernst, 1974, 1988; Barcelo and Poschenrieder, 1990; Kabata-Pendias and Pendias, 1992). Mine spoil dumps usually have barren surfaces, with rare plants that show signs of suffering such as stunted growth, chlorosis, necrosis and anomalous development of roots with respect to shoots.

The evaluation of plant metal concentrations can be used to get information about specific plant behaviour in this environment and also to complete data about metal dispersion, with reference to their mobility to the biomass. Metal concentration in plants is a function not only of the total soil concentrations but depends also on the chemical speciation of metals in soils and soil solutions (Sposito, 1983; Sposito and Page, 1984; Kabata-Pendias and Pendias, 1992) and on the involvement of the metal in biological functions (Thornton, 1983; Bowie and Thornton, 1985; Adriano, 1986; Kabata-Pendias and Pendias, 1992). The evaluation of metal uptake by plants coupled with geobotanical observations can be used to find plant populations able to tolerate the particularly severe environmental conditions of waste-rock dumps. These plants could be used in revegetation programs aimed at the reduction of the environmental impact of mining areas (Ernst, 1988).

The present study is concerned with changes in metal concentrations and distributions in some plant

375

376 E. Dinelli and A. Lombini

species growing on a copper sulphide mine spoil. Attention has been paid to Silene armeria, a species that previous orientation surveys in the same area (Dinelli, 1994; Dinelli and Lombini, 1994) indicated as tolerant to this peculiar environment. Populus and Salk species were also considered. The comparison with other S. armeria populations from uncontami- nated sites is in progress (Lombini et al., 1995) but we present here some preliminary data concerning S. armeria growing on a serpentinite outcrop from the Prinzera area, about 40 km E of the mine spoil area.

STUDY AREA

The study area is located in the NW sector of the Northern Apennines (Italy) along the Nure river valley (Fig. la), a tributary of the PO river. In the area outcrops are sedimentary rocks, mainly flysch and shales of Cretaceous to Paleogene age belonging to the Ligurian sequence, and ophiolitic rocks (basalts, serpentinites and rare gabbros), as olistholits in the sedimentary sequence (Braga, 1963; Boni et al., 1971).

The Vigonzano mining area is located between 750 and 800 m above sea level, on a SW facing slope in Rio della Lobbia valley, a Nure river tributary (Fig. lb). The area has continental climatic conditions, with average precipitation of 1200 mm/a, with spring and autumn maxima; a mixed deciduous oakwood (Quercuspubescens Willd, Ostrya carpi- nifolia Stop.) dominates in the area. In the Vigonzano area a group of small ophiolitic masses (basalts and basaltic breccias and minor serpentines and gabbros) occur as olistholits within the “Areille a Palombini di Barberino” (Braga, 1963; Boni et a/.,7971), a complex of grey-bluish slates including small lenses of greyish limestones and ophiolitic rocks. Metalliferous manifestations are rather common and almost every ophiolitic outcrop shows signs of mine workings or trials.

Chalcopyrite, pyrite and magnetite are the main ore forming minerals. Iron and copper sulphides mineraliza- tions are hosted in serpentinites, and basaltic breccias (Bertolani, 1959; Scicli, 1972; Castaldo and Stampanoni, 1975; Zuffardi, 1977). Ores are generally located at the boundary between ophiolitic rocks and pelitic sediments. Mining activity ceased in 1965 after the extraction of about 300,000 tons of rock, with an average Cu content between 2 and 4% (Scicli, 1972). Associated with mine workings there are waste rock dumps, clearly detectable for their yellowish colour, due to the abundance of iron hydroxides, and to the low vegetation density. These dumps cover a total area of about 0.3 km’.

Waste-rock dumps are composed of various rock types such as barren rocks (serpentinites, basalts and subordinate limestones and shales), fine grained ore minerals, ore weathering products (mainly Fe hydroxides) and smelting rejects. Dump material is heterogeneous in grain size, with coarse fragments prevailing and is extremely permeable (Dinelli, 1994).

Stunted woody plants form a transition to the surrounding prevailing woodland and are diffused in the lower flat part of the mine wastes too. The botanical features of the Vigonzano mine spoil area are influenced by morphology and water circulation: on steep slopes the occurrence of plants is limited whereas in the flat parts of the mine spoil area where substrate is more stable and water circulation intense the vegetation cover is larger. Clearly defined corridors of vegetation, dominated by Silene armeria L. and Equisetum arvense L. occur along main draining rills. Phragmites communis L. occurs in a small central bog collecting mine spoil waters, where Salix spp., Populus nigra L. and P. tremula L. also occur.

MATERIALS AND METHODS

Plant samples growing on the Vigonzano waste rock dumps were collected in autumn 1993 and in spring and summer 1994 at the same sampling points. They are either herbs: S. armeria (Caryophyllaceae), Salix spp. (Salicaceae) and P. nigra (Salicaceae). The growth area of the S. armeria population is the lower flat zone of the mine spoils dump (sites A8 and DN). The plants of site A8 are mainly caespitose, showing greater size and age when compared to the plants of site DN. The sampling of S. armeria at site A8 (over an area of about 5 x 3 m’) was carried out on 3 occasions over a 4 month period (April-July 1994) in order to obtain samples representative of the main stages of the plant cycle (early vegetative; flowering and early senescent). At the site DN (2 x 1 m’) S. armeria plants were collected in only 2 different periods (September 1993 and April 1994). Five-ten individual plants of S. armeria were sampled randomly from each site. Some of these individual plants (at least 3) were grouped to obtain the “whole plant” samples; the other remaining individual plants were divided into their compo- nents (roots, leaves, stems and flowers).

On 3 different dates (September 1993, April and June 1994) P. nigra and Salix twigs were collected randomly between different individual plants taking into account the same physiological age at sites DO and DH respectively. The leaves originating from the same points of insertion in the twigs were sampled.

All the plants were carefully washed 3 times in deionized water. Attention was given to washing the roots, until visual inspection revealed that no soil particles remained adhering to the roots, and the deionized water used for washing was clear.

At each plant sampling site mine spoils were collected, sampling of the topsoil horizon (O-20 cm below topographic surface). Substrate chemical analyses (relative to the < 2 mm fraction) for major and trace elements were carried out by X-Ray Fluorescence Spectrometry on pressed powder pellets using a PHILIPS PW 1480 automated spectrometer following the methods of Franzini et al. (1972, 1975) Leoni and Saitta (1976) and Leoni et al. (1982) for matrix corrections.

The mine spoil pH was evaluated using standard conditions recommended by S.I.S.S. (1985) for soil pH measurements from a soil-deionized water suspension (1:2.5 ratio); pH was measured by an ION85 IONANALYZER equipped with a combined electrode. The suspensions used for pH measurements were centrifuged at 9000 rpm for 15 min and solutions retained for metal analyses after filtration. Water soluble metal concentrations of Cr, Fe, Ni, Cu, and Zn were measured by Flame Atomic Absorption with a Perkin-Elmer spectrometer mod. 5000.

The plant samples were oven-uried at 90°C overnight and homogeneized in an agate mortar. An homogeneized sample (0.4 g) was dissolved with a mixture of HN03, HF and HCleI (5: 1: 1) following the suggestions of Angelone et al. f 1993). Magnesium. K. Ca Cr. Fe. Co. Ni, Cu. and Zn have been analykd by Flame Atomic Absorption with a Perkin- Elmer mod. 5000 spectrometer. Accuracy was checked by means of duplicate analyses on selected samples (less than 10% relative variation). Interbatch variations were mon- itored by repeated analyses of selected samples in the various analytical batches (less than 10% variation).

RESULTS AND DISCUSSION

Mine spoil geochemistry

Bulk chemical composition of the sampling sites is reported in Table 1, the average composition of

Metal distribution in plants on copper mine spoils 377

Fig. 1. (a) Schematic geological map of the Rio della Lobbia Valley (modified from Braga, 1963 and Boni et al., 1971) and (b) details of the Vigonzano mine spoil area. (a) 1, ophiohtic rocks; 2, “Palombini” shales; 3, Monte Caio, Vat Luretta and Monte Penice Flysch Formations; 4, Scabiazza Sandstones; 5, post-Eocene Formations and Quaternary cover. For the mining area (b) sampling point are reported and outcrops of ophiohte related rocks: 6, basalts and basaltic breccias; 7, gabbros; 8, serpentinites; 9, mine spoil areas.

White area represents “Palombini” shales.


‘Ofi 1

0.1

0.01

nm,

DN DN A8 A8 A8 A8 PM sepl’93 spr ‘94 apr ‘91 apr 94 jutlv4 jul 94 may ‘94

Fig. 5. BAC of Silene armeria in the sampling sites A8 and DN within Vigonzano mine spoil dump. Data relative to the Prinzera area are reported for comparison.


Table 1. Chemical composition and Ca/Mg ratio of the Vigonzano mine spoil (see sampling locations in Fig. 1) and Prinzera sampling sites. The average ultramafic rock (UFM) composition from (Faure, 1992) is reported for comparison

A8 mine spoil

DH mine spoil

DN mine spoil

DO mine spoil

PRI serpentinite

Avg UFM (Faure, 1992)

(WtX) SiOz 44.43 41.39 44.05 43.58 39.30 42.36 TiOz 0.57 0.93 0.81 0.78 0.13 0.05 A1203 6.08 8.43 6.98 6.31 3.30 2.27 Fe203 15.28 16.24 16.7 17.11 9.30 13.78 MnO 0.06 0.09 0.09 0.07 0.14 0.20 MgO 23.07 19.94 19.22 21.76 30.46 38.47 CaO 1.39 1.90 2.11 0.99 0.47 2.24 Na2 0.20 0.48 0.86 0.34 0.09 0.66 K2O 0.05 0.08 0.19 0.23 0.12 0.02 p205 0.04 0.09 0.10 0.05 0.05 0.04 LO1 8.83 10.44 8.88 8.79 16.66 Ca/Mg 0.08 0.11 0.13 0.05 0.01 0.07 Cr (ppm) 1525 1478 1688 1691 3503 1800 Ni 1292 769 829 958 2540 2000 co 118 96 114 126 156 175 cu 1354 1647 1786 2110 20 15 Zn 56 54 64 66 150 40 S 7170 863 1525 1170 nd 200

nd: not detected.

ultramafic rocks (from Faure, 1992) is reported for comparison. The minespoil chemical composition is rather homogeneous, with high concentrations of Fe20stot and MgO and low Ca/Mg ratio. Copper concentration in the mine dumps is always above 1500 ppm due to the presence of ore minerals and their weathering products. The high concentration of Mg, Co, Cr and Ni are due to the abundance of serpentinite rock fragments in the waste rock dump. Zinc concentration (average 62 ppm Zn) does not suggest the presence of Zn ore minerals in mine spoils, even if studies related to the Vigonzano ore minerals indicate the presence of significant Zn concentrations (about 700 ppm Zn) in pyrite (Dinelli, unpublished data). The S concentrations in Table 1, are consider- ably larger than average UFM (Ultramafic Rock Composition), can be used to evaluate the abundance of ore fragments in mine spoil dumps. The composition of the Prinzera serpentinite soil is comparable with average UFM, however it is slightly depleted of SiO2, Fe20Jtot and MgO, and enriched in Cr and Ni as a consequence of pedogenesis.

Total soil concentrations are not usually considered synonymous with metal availability to plants because no information about their mobility in the environment is given. Water soluble metal fractions may be useful in the evaluation of metal mobility since they can identify with good confidence the composition of soil solutions (Ure, 1990; Martycak et al., 1994). Data relative to pH, water soluble concentrations and fractions are reported in Table 2 respectively. Water soluble concentrations for Cr, Fe, Ni, Cu, and Zn indicate that Cu is the element with the largest solution concentrations in the mine spoil material.

Chromium concentrations are low, in most cases below analytical detection limits.

Comparison of metal water extractable fractions identify an extraction sequence of the type: ZnlCu > Ni > CrzFe, as shown by Dinelli (1994) and Dinelli and Lombini (1994) using a wider data set. Metal mobility is mainly controlled by pH conditions: low pH values generally enhance Cu, Ni and Zn mobility in mine spoil soil solutions. Metal mobility is, however, limited by the presence of Fe hydroxides, whose adsorption capacity for these elements reaches a maximum in this pH range (Dinelli, 1994; Dinelli and Lombini, 1994).

Plant seasonal variations

The concentrations of macronutrients (Mg, K, Ca and Fe) and microelements (Cr, Co, Ni, Cu and Zn) in S. armeria (from the Vigonzano mine spoil and Prinzera areas), in the leaves of Sulix spp. and P. nigra (the Vigonzano mine spoil area) are reported in Table 3 ordered according to sampling site and date. Table 3 reports also data relative to the dry weight (DW) of the S. armeria samples, used in the following discussion.

The S. armeria growing on the contaminated land have high trace metal concentrations when compared to those growing on the serpentinite outcrop. The greatest differences are for Cu concentrations, but Zn and Co also show slight variation, reflecting the contamination of the Vigonzano area. Metals tend to be concentrated in leaves and the oldest leaves usually have high metal concentrations (see old leaves in April


Table 2. (a) pH, water soluble metal concentrations (mg/L) and (b) water soluble metal fraction (WSF, in % units) for each sampling point

(a) A8 DH DN DO

PH 4.07 4.53 3.85 3.89

nd 0.003 0.002 nd Fe Ni CU Zn

(b)

0.018 0.020 0.027 0.026 0.097 0.008 0.022 0.052 0.664 0.170 0.341 0.740 0.146 0.002 0.012 0.019

A8 DH DN DO

W) Cr 2.0 x 10-4 1.0 x 10-S - Fe 1.7 x lo-5 1.8 x 1O-5 2.0 x 10-5 1.7 x 10-j Ni 7.0 x 10-3 1.0 x 10-3 3.0 x 10-3 5.0 x 10-j cu 4.0 x 10-2 1.0 x 10-2 1.9 x 10-2 3.5 x 10-2 Zn 26 x lO-5 0.4 x 10-2 1.9 x 10-Z 2.8 x lo-*

1994 and basal leaves in July 1994 sampling, A8 in Table 3). The differences in metal concentration due to leaf position and/or leaf age are governed by the transpiration rate (Ernst, 1993). Only Zn does not display such an enrichment probably because it is governed by active transport. Generally the content of K decreases with plant ageing whereas Ca and Mg concentrations sometimes increase (Mengel and Kirby, 1982). Young leaves, therefore, show relatively high contents of K while in the older leaves an accumulation of Ca can be observed (Table 3).

The seasonal variations of metal concentrations in S. armeria are represented in Fig. 2. In general, considering the whole plants, the element concentrations were higher in April, during the early vegetative growth stage, and in July when the plants display a “parched” habit. The causes of this trends in the seasonal variations in metal content are probably due to several factors including: dilution brought about by the spring flush of plant growth, differences in the mechanisms that control the form and translocation of metals in the plant and the process of senescence.

In the early stages of the growing season the nutrient content increases, due to a relatively higher nutrient uptake as compared with the growth rate (Fig. 2, April sampling). As soon as the “tiller@ stage” is completed, the very high growth rate of stem elongation begins. This vigourous growth causes a reduction in the mineral content of the plant by dilution. Once the “heads” are fully developed (flowering stage), the minimum values for almost all elements, in terms of the whole plant (Fig. 2, June sampling), are found. Within the plant, however, considerable changes occur between tissues for the remobilization of some essential metals (e.g. K in the flower of July sampling). In the following stages variations in soil, air temperature and light intensity affect both the uptake by roots and translocation to the tops. A high transpiration rate, caused by moisture

deficit of the ambient air, coupled to a decrease in fluid circulation due to senescence, enhances the concentration of the metals (concentration effect in July samples).

The leaf/whole plant ratios were calculated (total mass of the element in the leaves/total mass of the element in the whole plant) to evaluate the percentage transport of the elements (Fig. 3). The “stems” samples of July were not analysed so that higher values in percentage for this set of data were obtained. However, it is noteworthy that in April, during the vegetative growth stage, the percentage of transport is high for all elements, and then decreases. Only Cu percentages do not change through time, because higher Cu concentrations are observed in the leaves (compare Figs 2 and 3). The lack of change in Zn concentrations during the observation period is evident (compare Figs 2 and 3). The percentage of transport of Zn compared to those of Ni and Cr does not change significantly after the June sampling and the transpiration effect is negligible. For Co the correlation between the decrease in concentrations in the leaves and the decrease in the percentage of transport is clear (compare Figs 2 and 3). The effect of transpiration on Ca is much higher compared to Mg and that on K is negligible. The reason could be the abundance of these 2 latter elements in the phloem sap (K > > Mg), which is characterized by very low Ca concentrations. The high proportion of total Ca in the plant tissue is actually located in the apoplast (Marschner, 1986), well represented by sampling in July during the plant senescent stage (Figs 2 and 3).

Data relative to microelements plus Fe in Salix spp. and P. nigra leaves from September 1993 to June 1994 (Fig. 4) seem to indicate an increase in metal translocation to leaves in the early growth stage, followed by a more or less marked fall in the mature growth stage; data relative to September 1993,


Table 3. Plant concentrations @g/g) for Cr, Fe, Ni, Co, Cu and Zn and for macronutrients Mg, K, Ca. Samples are ordered according to sampling site and to sampling date. Dry weights (DW) of Silene artneriu samples are reported

Site Date Plant tissue DW (g) Cr Ni Co Cu Zn Mg K Ca Fe CalMg

Silene armeria DN Sept ‘93

Sept ‘93 Sept ‘93 SeDt ‘93

DN A& ‘94 Apr ‘94 Apr ‘94 Apr ‘94 Apr ‘94

Silene artneria A8* Apr ‘94

Apr ‘94 Apr ‘94 Air ‘94 ADS ‘94

A8 A& ‘94 Apr ‘94 Apr ‘94

A8* Jun ‘94 Jun ‘94 Jun ‘94 Jun ‘94 Jun ‘94

A8* Jul.94 Jul’94 Jul’94 Jul.94 Jul.94 Jul’94

Silene armeria PRI May ‘94

May ‘94 May ‘94

Salk spp. DH Sept ‘93

Apr ‘94 Jun ‘94

Populus nigra DO SeDt ‘93

Air ‘94 Jun ‘94

Whole plant 3.30 10 78 na* 381 35 10820 Leaves 1.83 36 100 na 320 16 13080 Roots 0.35 14 47 na 63 31 3650 Flowers 0.50 43 65 na 100 45 5690 Whole plant 3.10 35 63 28 219 165 9170 Young leaves 3.62 9 19 13 31 79 5650 Old leaves 3.62 52 56 16 165 72 7220 Leaves 4.13 23 33 13 104 86 5910 Roots 1.23 26 22 11 65 3670

Whole plant 0.66 12 44 31 81 90 Young leaves 2.02 6 29 17 47 89 Old leaves 0.86 12 55 37 275 87 Leaves 2.47 9 51 27 121 105 Roots 0.68 24 37 28 143 100 Whole plant 2.81 43 127 37 170 119 Leaves 1.19 16 116 31 326 16 Roots 0.24 23 48 24 155 87 Whole plant 10.43 29 18 6 66 83 Leaves 11.58 91 76 15 174 106 Roots 1.30 29 15 7 51 174 Stems 12.42 106 66 4 31 78 Flowers 1.50 18 10 8 27 136 Whole plant 15.10 75 57 14 161 92 Leaves 1.80 41 22 8 13 101 Basal leaves 2.90 138 126 20 504 114 Stems 19.20 na na na na na Roots 1.60 52 30 10 91 64 Flowers 4.00 36 20 7 49 89

Whole plant 1 .oo 16 41 6 10 56 6630 6810 8340 850 1.26 Leaves 2.00 11 27 4 8 62 8380 8340 12110 550 1.44 Roots 0.22 97 97 15 24 11 5000 4180 3280 6130 0.65

Leaves 5 22 na 11 119 11210 170 30360 310 2.69 Leaves 46 34 24 44 199 2480 2180 9260 320 3.13 Leaves 10 9 13 10 115 4920 530 18170 110 3.10

Leaves 9 69 na 11 19 8530 260 22900 290 2.69 Leaves 12 33 14 22 195 5080 3130 9620 690 1.89 Leaves 9 19 11 8 164 5480 3040 22410 220 4.09

1960 6930 1830 8440 4470 6480 7040 3400 5360

10380 2500 2110 4110 7750

10100 12140

3zlo 5110

11580 5370 4010 5300 1400 6040 2280 5020 11260 2290 3440 4170 3140

3730 5210 1150 3000 6910 2240 7650 2260 2570

810 2420 2220 6140 1180 2650

160 na 930

1500

8710 11790 2650 3880

15720 10800 14120

11950 6880

19600 12380 4000 9510

19460 11650 6400

11800 6250 4030 4250

13900 20670 18000

4nsalO 5240

1780 4720 1050 2930 5010 930

4920

1280 650

1400 960

1680 6080 1820 2560 2060 690

1210 890 610 590

2050 1470

GO 2920

0.80 0.90 0.73 0.68 0.55 1.91 1.96 1.90 1.13

1.55 0.99 2.50 1.47 0.89 1.50 2.76 3.42 1.19 1.71 2.50 1.81 1.02 1.79 2.04 1.48

/s”O 1.01

Ranges of toxicity for selected elements in plants (from Kabata-Pendias and Pendias, 1992) Cr Ni co cu

5-30 10-100 15-50 20-100 Zn

100-400

* Caespitose plants. na: not analysed.

however, seem to indicate that with senescence an increase in metal concentrations has to be expected due to concentration caused by loss of fluids.

Plant-soil relations

Metal accumulation by plants can be evaluated using a simple index (Alloway et al., 1988), defined as Biological Accumulation Coefficient (BAC = metal

content in plant/total soil metal concentration). The BAC values for Zn, Cu. Co, Ni, Cr and Fe in the S. armeria samples from polluted and non-contaminated sites are reported in Fig. 5. The BAC values of the Vigonzano sites do not change significantly, suggesting that plant absorption is not a function of total soil concentration; whereas those of the Prinzera site are markedly different. Zinc is the element with the highest BAC values among the S. armeria samples (in almost all cases above l), except in the PRI site.


apr 94 june 94 july 94

leaves P

ir94 june 94 july 94


1 +Cr +Cu+Zn+Ni+Co 1

june 94 july 94


0' apr 94 june 94 julY 94

1 -N--Fe-U-Mg-tCa +K]

Fig. 2. Variations of metal concentrations in S&W armeria relative to whole plant, leaves and roots at sampling site A8.


Transport % (mess in leaves I mess in the whole plent)

1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1

0 AS A8

apr 94 j&Z894 july 94

-m- Cr

-o- cu + Zn + Ni

-A-- co

* Fe

- MS -+- Ca -X- K

1.0

0.9

0.8

0.7 0.6 0.5 0.4 0.3 0.2


Fig. 3. Variations in transport percentage in She armeria at sampling site A8.

The Zn biologic roles (Adriano, 1986; Kiekens, 1990; Kabata-Pendias and Pendias, 1992), its high concentration in mine spoil solutions favoured by low pH (Table 2) and the low Ca concentrations in soil material, a Zn antagonistic element (Kabata-Pendias and Pendias, 1992) are all possible explanations for

50

0 sept ‘93 apr ‘94 jua ‘94

+Cr -C-Fe -+- Ni

*co -cu *zn

1 4 I

sep ‘93 apr ‘94 jua ‘94

Fig. 4. Seasonal variations in (a) Salix spp and (b) Popuh nigra leaves.

this result. The other elements have BAC values generally below 0.5 and very low BAC values (~0.05) are observed for Cr and Fe, irrespective of the sampling area.

The slight variations in BAC values, due to seasonal variations in the metal concentrations in plants, do not change the general trend of metal accumulation in S. armeria growing in the Vigonzano mine spoil area. A sequence of decreasing BAC values: Zn > Co > Cu > Ni > Fe > Cr can be generalized for S. armeriu of the Vigonzano mine spoil area. This sequence exactly matches that reported before for water leaching tests (Zn > Cu > Ni > Fe > Cr), except for Co, which was not analysed, suggesting that soil solution composition may actually control metal uptake by plants in mine spoil areas. The situation for S. armeriu growing on the serpentinite outcrops of the Prinzera area is different for the relatively high copper BAC values observed. These preliminary data from an unconta- minated site may suggest an affinity of S. armeria for Cu absorption, proven by high Cu BAC values in the Prinzera area and confirmed by the absence of toxicity symptoms in the plants growing on a Cu polluted soil (the Vigonzano mine spoil area).

CONCLUSIONS

Chemical characterization of the Vigonzano mine spoil dump revealed high concentrations of Fe, Mg, Co, Cu, Cr, Ni and S some of them related to sulphide mineralization (Fe, Cu, S), the others to serpentinite rock abundant in the mine spoil material. High metal concentrations and soil acidity represent primary limiting factors for plant growth on the mine spoil surface area. Water leaching tests on mine spoil material, intended to represent the conditions of soil solutions, point out the following order of extraction: Zn?Cu>Ni > FezCr, with Cu being the element present with the largest concentration in soil solution.

The selectivity of the mine-spoil environment is


reflected by the low diversity in plant species, in fact only pioneering and highly tolerant species can survive without any sign of suffering in these severe environmental situations. The plant species S. armeria is rather widespread in the Vigonzano mine spoil area, it is characterized by high metal concentrations (up to 504 pg/g Cu, 174 pg/g Zn, 127 pg/g Ni and 138 pg/g Cr) and does not show signs of suffering. Comparison with a S. armeria population growing on a non- polluted environment, but still on serpentinite, con- firms the ability of this species to tolerate high metal concentrations.

Seasonal variations in plant uptake were evaluated, with particular attention to S. armeria, Salix spp. and P. nigra, by repeated sampling. Plant absorption for S. armeria is active in the root zones in the early growth stages, when nutrient needs are larger and this is testified also by high macronutrient concentrations. With plant maturity and warmer climatic conditions, transpiration is favoured and metal translocation to plant top is the result. In senescent stages metal tends to be concentrated in the leaves (September 1993 and basal and old leaves at other sampling times).

Metal absorption by plants, evaluated by means of BAC, indicates Zn as the element most actively absorbed (almost in every case > 1) by plants growing in the Vigonzano mine spoil areas. An absorption sequence Zn > Co > Cu > M > Fe > Cr can be generalized for plants growing on the mine spoil area that significantly matches the sequence outlined above for water leaching tests. This may suggest that plant absorption is controlled by soil solution composition and in fact plant concentrations are higher where humid soil conditions are encountered.

Acknowledgements-We would like to thank Professor F. Lucchini for the critical reading of the manuscript and his constant support. P. Trentini is kindly acknowledged for his technical support in FAAS analyses. Suggestions from two anonymous reviewers have improved the manuscript. The work- was supported by M.G.R.S.T. 60% funds,- grants Professor G. Simboli and Professor C. Ferrari.

Editorial handling: Dr Ron Fuge.

REFERENCES

Adrian0 D. C. (1986) Trace Elements in the Terrestrial Environment. Springer, New York.

Alloway B. J., Thornton I., Smart G. A., Sherlock J. C. and Quinn M. J. (1988) The Shipham report. 4. metal availability. Total Environ. 75, 41-69.

Angelone M., Vaselli O., Bini C. and Coradossi N. (1993) Pedogeochemical evolution and trace elements availability to plants in ophiolitic soils. Sci. Total Environ. 129, 391-309.

Barcelo J. and Poschenrieder C. (1990) Plant water relations affected by heavy metal stress: a review. J. Plant Nutr. 13, l-31.

Bertolani M. (1959) Ricerche su rocce prasinitiche ed anfibolitiche e sul giacimento metallifero di Vigonzano. Atti Sot. Nat. Mat. Modena 89190, 1121128.

Boni A., Braga G., Gelati R., Laureri S., Papani G., Petrucci F. and Venzo S. (1971) Note illustrative della Carta Geologica d’ltalia, Scala 1:100000, Foglio 72, Fiorenzuola d’Arda, 93 pp.

Bowie S. H. U. and Thornton I. (1985) Environmental Geochemistry and Health. D. Reidel, Dordrecht.

Braga G. (1963) Geologia delle valli Nure e Perino (Appennino piacentino). Atti 1st. Geol. Univ. Pavia 16, 18.5-195.

Castaldo G. and Stampanoni G. (Eds) (1975) Memorie illustrative della carta mineraria d’Italia. Scala 1: 1 .OOO.OOO. Mem. descr. Carta Geol. d’ltalia XIV, 212 pp.

Davies B. E. (1980) Trace element pollution. In Applied Soil Trace Elements (ed. B. E. Davies), pp. 287-351. Wiley, New York.

Davies B. E. (1983) Heavy metal contamination from base metal mining and smelting: implications for man and his environment. In Applied Environmental Geochemistry (ed. I. Thornton), pp. 425-462. Academic Press, London.

Dinelli E. (1994) Studio ambientale della dispersione di elementi chimici in aree di miniera nella regione Emilia-Romagna. Tesi di Dottorato, 203 pp. Univ. di Bologna.

Dinelli E. and Lombini A. (1994) Metal mobility and plant uptake in copper sulphide mine spoil dump (Vigonzano mine, Northern Apennines, Italy). Miner. Petrogr. Acta XXXVII, 125-140.

Ernst W. H. 0. (1974) Schwermetallvegetation der Erde. Fisher, Stuttgard.

Ernst W. H. 0. (1988) Response of plants and vegetation to mine tailings and dredged materials. In Chemistry and Biology of Solid Wastes. Dredged Material and Mine Tailings (eds W. Salomons and U. Fiirstner), pp. 54-69. Springer, Berlin.

Ernst W. H. 0. (1993) Geobotanical and biogeochemical prospecting for heavy metal deposits in Europe and Africa. In Plants as Biomonitors: Indicators for Heavy Metals in the Terrestrial Environment (ed. B. Markert), pp. 107-126. VCH, Weinheim.

Faure G. (1992) Principles and Applications of Inorganic Geochemistry. Macmillan, New York.

Franzini M., Leoni L. and Saitta M. (1972) A simple method to evaluate the matrix effects in X-Ray fluorescence analysis. X-Ray Spectrom. 1, 151-154.

Franzini M., Leoni L. and Saitta M. (1975) Revisione di una metodologia analitica per fluorscenza-X, basata sulla correzione completa degli effetti di matrice. Rend. Sot. ft. Min. Petrol. 31, 365-378.

Kabata-Pendias A. and Pendias K. (1992) Trace Elements in Soils and Plants. 2nd edn. CRC Press. Ann Arbor.

Kiekens L. 61990) Zinc. In Heavv Metals in Soils (ed. B. J. Alloway),‘pp. 261-279. Black& Glasgow. .

Lombini A., Pandolfini T., Ferrari C. and Dinelli E. (1995) Cu-tolerance and accumulation of two populations of Silene armeria L. from a copper-mine and from a serpentinite outcrop (northern Apennines, Italy). In Deuxieme Conference Internationale sur I’Ecologie des milieux serpentiniques. Noumea, 3117-518 1995.

Leoni L. and Saitta M. (1976) X-ray fluorescence analysis of 29 trace elements in rock and mineral standard. Rend. Sot. It. Min. Petrol. 32, 497-510.

Leoni L., Menichini M. and Saitta M. (1982) Determination of S, Cl, and F in silicate rocks by X-Ray fluorescence analyses. X-Ray Spectrom. 11, 156-158.

Marschner H. (1986) Mineral Nutrition of Higher Plants. Academic Press, London.

Marty&k K., Zeman J. and Vacek-Vesely M. (1994) Supergene processes on ore deposits-a source of heavy metals. Environ. Geol. 23, 156165.

Mengel K. and Kirby E. A. (1982) Principle of Planr Nutrition, 3rd edn. Int. Potash Inst., Bern.


Rose A. W., Hawkes M. E and Webb J. S. (1979) Geochemistry in Mineral Exploration, 2nd edn. Academic Press, London.

Scicli A. (1972) L’attivita estrattiva e le risorse minerarie della Regione Emilia Romagna. Artini, Modena.

S.I.S.S. (1985) Metodi normalizzati di analisi de1 suolo. Edagricole, Bologna.

Sposito G. (1983) The chemical forms of trace metals in soils. In Applied Environmental Geochemistry (ed. I. Thornton), pp. 121-170. Academic Press, London.

Sposito G. and Page A. L. (1984) Cycling of metal ions in the soil environment. In Metal Ions in Biological Systems,

Vol. 18, Circulation of Metal Ions in the Environment (ed. H. Siegel), 287-332. Marcel Dekker, New York.

Thornton I. (1983) Geochemistry applied to agriculture. In Applied Environmental Geochemistry (ed. I. Thornton), pp. 231-266. Academic Press, London.

Ure A. M. (1990) Methods of analysis for heavy metals in soils. In Heavy Metals in Soils (ed. B. J. Alloway), pp. 40- 80. Blackie, Glasgow.

Zuffardi P. (1977) Ore/mineral deposits related to the mesozoic ophiolites. In Time and Strata-bound Deposits (eds D. D. Klemm and H. J. Schneider), pp. 314-323. Springer, Berlin.

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