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Biscutella laevigata has recently been recognized as a species able to accumulate large amounts of cadmium. The experiments reported in this paper were conducted on two geographically isolated populations of B. laevigata in Poland. Both populations grow on metalliferous soils: a lead-zinc (calamine) waste heap in Bolesław near Olkusz (189 mg Cd/kg d.m.) and limestone rock in the West Tatra Mts (1.4-6.1 mg Cd/kg d.m.). The two populations were compared after cultivating them in medium containing cadmium salt (2-120 mg/dm3) for 3-30 days. Root-to-shoot transport of cadmium was higher in the waste-heap population than in the mountain population. In the waste-heap population, large amounts of cadmium were transported to the oldest leaves, reaching levels even twice those of the mountain population. This shows that the ability to hyperaccumulate metals may be a property of a population, not an entire species, and that the ability to accumulate cadmium in the oldest (withering) leaves may be a way the plant eliminates the toxic metal. Histochemical detection of cadmium (with dithizone) in tissues showed that it was taken up by the root hairs and then transported through vascular bundles to the leaves. The surface cells of the leaves, the epiderm and hairs accumulated particularly large amounts of cadmium. The leaves of the B. laevigata waste-heap population are much more thickly covered by hairs than those of the mountain population; we suggest that the ability to accumulate cadmium in leaf hairs may be a mechanism of detoxifying and hyperaccumulating cadmium in the shoots of that population.
W rejonie olkuskim (Wyżyna Śląsko-Krakowska) w wyniku wielowiekowej działalności górniczej ukształtował się swoisty krajobraz poprzemysłowy. Na obecnych tam hałdach, bogatych w metale ciężkie (Zn, Pb, Cd) występuje charakterystyczna roślinność galmanowa, która rozwinęła się spontanicznie na drodze długotrwałej sukcesji. Jednym z przykładów jest ponad stuletnia murawa na starej hałdzie w Bolesławiu, której unikatowy charakter oraz obecność wielu gatunków chronionych, a w tym także i rzadkich, świadczy o jej istotnych walorach. Ze względu na występowanie pleszczotki górskiej (Biscutella laevigata) obszar ten został objęty ochroną prawną w formie użytku ekologicznego. W murawie przez długi czas występowała nielicznie sosna pospolita (Pinus sylvestris). Obecnie jednak rozrastające się drzewa pokrywają murawę w znacznie większym stopniu. Warunkiem zachowania w krajobrazie charakteru użytku jest ograniczenie w nim rozwoju sosny. Konieczne jest zatem wprowadzenie aktywnej ochrony polegającej na wycinaniu drzew i monitorowanie jej efektów
Biscutella laevigata L. is known as a Tl hyperaccumulator. In Poland Biscutella laevigata occurs in the Tatra Mts (Western Carpathians) and on the calamine waste heap in Bolesław near Olkusz (Silesian Upland). The purpose of this work was to evaluate whether plants of both populations were able to accumulate an elevated amount of thallium in their tissues. The plants were cultivated in calamine soil in a glasshouse for a season and studied at different ages – from 2-week-old seedlings to 10-month-old adults. Additionally, the plants were grown for ten weeks in calamine soil with EDTA to enhance Tl bioavailability. The total content of Tl in plant tissues after digestion was determined by ICP-MS, whereas its distribution in leaves was studied by LA-ICP-MS. Of the total content of Tl in the soil in the range of (15.2–66.7) mg·kgˉ¹d.m., only (1.1–2.1) mg·kgˉ¹d.m. was present in a bioavailable form. The mean content in all the plants grown on the soil without EDTA was 98.5 mg·kgˉ¹d.m. The largest content was found in leaves – 164.9 mg·kgˉ¹d.m. (max. 588.2 mg·kgˉ¹d.m.). In the case of plants grown on the soil enriched with EDTA, the mean content in plants increased to 108.9 mg·kgˉ¹d.m., max. in leaves – 138.4 mg·kgˉ¹d.m. (max. 1100 mg·kgˉ¹d.m.). The translocation factor was 6.1 in the soil and 2.2 in the soil with EDTA; the bioconcentration factor amounted to 10.9 and 5.8, respectively. The plants from both populations did not contain a Tl amount clearly indicating hyperaccumulation (100–500 mg·kgˉ¹d.m.), however, high (>1) translocation and bioconcentration factors suggest such an ability. It is a characteristic species-wide trait; B. laevigata L. is a facultative Tl hyperaccumulator. The largest Tl amount was located at the leaf base, the smallest at its top. Thallium also occurred in trichomes, which was presented for the first time; in this way plants detoxify Tl in the above-ground parts. Leaves were much more hairy in the Bolesław plants. This is an adaptation for growth in the extreme conditions of the zinc-lead waste heap with elevated Tl quantity.
Two plant species growing on calamine spoils (vicinity of Olkusz, S. Poland) were examined for their ability to accumulate metals. The plants in these pilot studies were Biscutella laevigata L., a rare plant that occurs in lowlands on zinc-lead mine spoils only in the vicinity of Olkusz, and Plantago lanceolata L. which is a common species in Poland. Concentrations of alkaline metals (Ca, K, Mg) and heavy metals (Cd, Fe, Mn, Pb, Zn) in soil and plants (shoots, roots) from two locations of calamine spoils 100 and 30 years old and control areas were determined. Soils from the mine spoils were alkaline (pH >7.4), with large concentrations of Ca and Mg. Concentrations of Cd, Pb and Zn in soil were up to 224 mg kg-1 3100 mg kg-1 and 78,000 mg kg-1, respectively. The amounts of exchangeable metals (1 M NH4NO3) were up to 9.51 mg kg-1 Cd, < mg kg-1 Pb, and 24.5 mg kg-1 Zn. Concentrations of heavy metals in plants from the calamine spoils and their distribution within plants depended on the species. B. laevigata accumulated heavy metals in roots (Cd) or shoots (Fe, Mn, Zn). P. lanceolata accumulated heavy metals mainly in roots. Maximum concentrations in roots and shoots of B. laevigata were 14.3 mg kg-1 Cd, 111 mg kg-1 Pb and 410 mg kg-1 Zn. P. lanceolata contained up to 65.6 mg kg-1 Cd, 157 mg kg-1 Pb and 2540 mg kg-1 Zn. Our data suggest that both species tend to exclude Cd, and P. lanceolata also Zn, present in large concentrations in the soil.
This paper reviews several studies dealing with the specific traits of plants growing on calamine waste heaps in the vicinity of Olkusz. The waste heaps here contain very high amounts of zinc, lead and cadmium. Particular traits distinguishing the calamine forms of the species Silene vulgaris, Dianthus carthusianorum and Biscutella laevigata make calamine plants potentially very useful for recultivating land polluted by heavy metals in Poland. Utilization of natural biological processes would seem to be the best approach to the problem of recultivation. Despite this, methods using local plant resources to reclaim areas polluted by high concentrations of heavy metals are still rarely used. The natural vegetation of areas characterized by high concentrations of heavy metals may be a valuable source of genetic material (ecotypes) ideally adapted for growth under the harsh and pioneering conditions of calamine waste heaps.
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