On the Holocene vegetation history of the Argive Plain (Peloponnese,southern Greece)

Palynological investigations have been carried out on a sediment core from ancient Lake Lerna, a former fresh water lagoon in the western part of the Argive plain, Peloponnese, southern Greece. The sequence starts at 6800 B.P. (5700 cal B.C.). The lowest part of the pollen diagram shows a period of open deciduous oak woods, which may have been influenced by human impact already (Zone I). It is followed by a period of dense deciduous oak woods (Zone II), which lasted until the beginning of the Bronze Age ca. 4800 B.P. (3500 cal B.C.). Later, the diagram indicates strong human influence such as woodland clearance, the spread of maquis, phrygana and pine in Zones IIIa-IV. During the Archaic, Geometric and Classical periods after ca. 2700 B.P. (800 cal B.C.) there is evidence of a phase of extensive olive farming (Zone IIIb). In the same zone, after a period of scattered finds, there is an almost continuous Juglans curve. Zone IV is characterised by high pine values. In Zones I-II the evidence of evergreen Mediterranean plants is surprisingly small. In times with no discernible human influence (Zone II), deciduous oaks dominate, with no evidence for a climax vegetation of the Oleo-Ceratonion alliance. Olea europaea is the only species of that alliance traceable by its pollen in the diagram, while Ceratonia pollen is totally absent.     

Optimization of in vitro bud induction and plantlet formation from mature embryos of Aleppo pine (Pinus halepensis Mill.)

Summary Studies were undertaken to optimize tissue culture conditions for micropropagation of Aleppo pine (Pinus halepensis Mill.) from mature embryos and various explants of the embryo. Over 90% of the embryo explants gave rise to adventitious buds within 4 wk. Intact embryos were the most suitable explants for shoot bud induction. Both isolated cotyledons and hypocotyls produced adventitious buds, but these developed slowly and failed to elongate. N⁶-Benzyladenine (BA) alone at 5.0μM was the most effective cytokinin when added to gelled to gelled von Arnold and Eriksson’s (AE) medium containing 3% sucrose. Adventitious bud development was achieved on hormone-free AE medium, and shoot elongation was optimum on three quarter-strength Bornman’s MCM medium, with 0.1% conifer-derived activated charcoal. Shoots were multiplied on three-quarter strength MCM medium, containing 5μM BA. To induce adventitious roots on the elongated shoots, pulse treatment with 1 mM IBA for 6 h, followed by the transfer of the shoots to sterile peat:vermiculite (1:1) mixture, was beneficial. After acclimatization for 3 to 4 wk under mist, almost all the rooted shoots could be transplanted successfully to the greenhouse, where the plants exhibited normal growth habit. Histologic studies on the ontogeny of adventitious shoot formation from mature embryo explants revealed temporal structural changes in different parts of the explant. Induction of mitotic divisions on the shoot-forming medium resulted in the formation of meristemoids in the epidermal and subepidermal layers of the explant, located initially at both the tips of the cotyledons and the axils of adjacent cotyledons. Shoot buds arising in the axils of adjacent cotyledons were due to new cell division and not to any preexisting meristem.     

Fate of lead in the soil and its effects onPinus halepensis

Summary Chemical analysis of samples of needles of Aleppo pine (Pinus halepensis), humus and mineral soil collected in the vicinity of the Pb-smelter in Lavrion, Attica, showed that an area of about 2 km around the smelter is heavily polluted primarily with Pb and also with Zn, S and F^–. Most of the Pb was found accumulated in the humus and the top layer of the mineral soil.About 50% of the Pb found in the samples of Aleppo pine needles could be removed by washing them in a dilute detergent solution. One and 15% of the total Pb from Pb-polluted soil and humus samples, respectively, was extracted with normal ammonium acetate solution. No Pb or a very small amount was extracted with distilled H₂O from humus and soil samples treated with concentrations of Pb as high as 3000 ppm and incubated in the laboratory for 30 days.Humus samples treated with up to 1500 ppm Pb or Pb-polluted humus samples collected from points leeward of the smelter had no adverse effects on the germination of Aleppo pine seeds. When the germination experiment was conducted on Pb-polluted humus samples from points windward of the smelter, where a temporary pine needle death had been observed, the percentage seed germination, for two years, was found reduced and negatively correlated to the distance of the humus sampling point from the Pb-smelter.In nursery experiments Pb concentrations of up to 2000 ppm, added to a calcareous soil, had no adverse effect on height increase of Aleppo pine seedlings. Very little Pb was transported from the roots to the needles after seven months growth of the seedlings on either Pb-amended soil or on Pb-polluted soil from Lavrion. Concentrations of Pb in the roots of the seedlings, however, were found high in both cases and almost proportional to concentrations of Pb in the soil.     

Migration of heavy metals in two Japanese soils

Summary The migration of common bio-toxic heavy metals in two typical soils of Japan under the influence of various leaching solutions was investigated.The results of the present study have indicated that the Pb and Cu ions were less mobile than those on Zn and Cd. Thus, the former two ions have largely been concentrated in the surface horizon while the latter two have been localised in the sub-surface layers. Ni has exhibited greater mobility than other heavy metals under all the leaching stress in both the soils. It is clear from the present study that Ni, Cd and Zn might pose a greater threat of ground water pollution than Cu and Pb. The specific migration properties of each metal ion varied depending on the nature of the ion and leaching solutions. The major soil factors governing the mobility of heavy metals in the soils have been discussed in the light of the results of the present investigation.     

Determination of Cd, Cu, Pb and Zn in neoplastic kidneys and in renal tissue of fetuses, newborns and corpses

The incidence of kidney tumors in USA and Europe (in particular, Central Europe and Italy) has been dramatically increasing since the 1970s, possibly as a consequence of ongoing environmental pollution. Environmental factors have been considered responsible for at least 80% of the incidence of neoplastic diseases. To shed some light on this issue, the amounts of Cd and Pb were measured in neoplastic tissue and adjacent normal part of kidney excised for carcinoma and compared with those in renal tissues of fetuses, newborns and subjects that died of non-neoplastic diseases. Cd and Pb were determined by Inductively Coupled Plasma Atomic Emission Spectrometry and Atomic Absorption Spectrometry with Electrothermal Atomization. Metallothionein immunoperoxidase staining technique was used to localize the accumulation of Cd and Zn in the nephrons. Content of Cd and Pb in kidneys of fetuses and newborns was extremely low. However, it was significantly increased in adjacent-normal tissues of kidneys with carcinomas, and significantly higher compared to kidneys of individuals that died of non-neoplastic diseases. In tumoral tissues of the excised kidneys, Cd content was very low, while that of Pb significantly elevated. High amounts of Cd and Pb in the adjacent-normal parts of kidneys with carcinomas are suggestive of possible, individual or synergistic, effects of these pollutants on enzymatic systems, priming an oncogenic pathway. Detection of metallothioneins, primary ligands of Cd, exclusively in the cells of proximal tubuli, i.e. wherein renal carcinoma develops in over 80% of cases, strongly supports the assumption that Cd exerts a carcinogenic effect.     

Changes in nutrient use efficiency, status and retranslocation in young post-fire regeneration Pinus halepensis in response to sudden N and P input, irrigation and removal of competing vegetation

The capacity of Mediterranean species to adapt to variable nutrient supply levels in a global change context can be a key factor to predict their future capacity to compete and survive in this new scenario. We aimed to investigate the capacity of a typical Mediterranean tree species, Pinus halepensis, to respond to sudden changes in N and P supply in different environmental conditions. We conducted a fertilisation, irrigation and removal of competing vegetation experiment in a calcareous post-fire shrubland with an homogeneous young (5 years old) population of P. halepensis in order to investigate the retranslocation and nutrient status for the principal nutrients (N, P, Mg, K, S, Ca and Fe), and the nutrient use efficiency (NUE) of the most important nutrients linked to photosynthetic capacity (N, P, Mg and K). P fertilisation increased P concentration in needles, P, N, Mg and K retranslocations, and NUE calculated as biomass production per unit of nutrient lost in the litterfall. The P fertilisation was able to increase the aboveground biomasses and P concentration 3 years after P fertiliser application. Those responses to P fertilisation were enhanced by the removal of competing vegetation. The N needle and litterfall concentration decreased after P fertilisation and this effect was greater when the P fertilisation was accompanied by removal of competing vegetation. The increase of P availability decreased the P-NUE and increased the N-NUE when these variables were calculated as aboveground biomass production per unit of P present in the biomass. Both P-NUE and N-NUE increased when calculated as total aboveground production per unit of nutrient loss. The results show that it is necessary to calculate NUE on a different basis to have a wider understanding of nutrient use. The irrigation did not change the needle nutrient concentrations and the litterfall production, but it significantly changed the nutrient litterfall concentrations and total aboveground contents (especially P and K). These results show a high capacity of P. halepensis to quickly respond to a limiting nutrient such as P in the critical phases of post-fire regeneration. The increase in P availability had a positive effect on growth and P concentrations and contents in aboveground biomass, thus increasing the capacity of growth in future periods and avoiding immediate runoff losses and leachate. This capacity also strongly depends on neighbour competition.     

Effects of copper,zinc, and cadmium ions on the production of phosphate from phytic acid by the phytase system in spruce forest soil

Summary The hydrolysis of phosphate from phytic acid by the acid soil phytase system was reduced in the presence of metal ions. Copper was most effective in this respect — zinc and cadmium were less inhibitory. Binding to metals did not completely inhibit the hydrolysis of phytic acid. At higher metal concentrations, where binding to other soil constituents, like humic acids, interfered less, the inhibition of the phytase activity was stronger than that of acid phosphatase.     

Heavy metal stress reduces the deposition of calcium oxalate crystals in leaves of Phaseolus vulgaris

Calcium oxalate (CaOx) crystals in plants may serve as a sink for the absorption of excess calcium, and they could play an important role in heavy metal detoxification. In this study, the effect of heavy metals and different calcium concentrations on the growth of calcium oxalate crystals in leaves of Phaseolus vulgaris was investigated. Different analytical techniques were used to determine the influence of exogenous lead and zinc on CaOx deposition and to detect a presence of these metals in CaOx crystals. We found a positive correlation between the calcium concentration in the nutrient medium and the production of calcium oxalate crystals in leaves of hydroponically grown plants. On the other hand, addition of the heavy metals to the nutrient medium decreased the number of crystals. Energy dispersive X-ray spectrometry did not detect the inclusion of heavy metals inside the CaOx crystals. Our investigation suggests that CaOx crystals do not play a major role in heavy metal detoxification in P. vulgaris but do play an important role in bulk calcium regulation.     

Stimulation by nickel of soil microbial urease activity and urease and hydrogenase activities in soybeans grown in a low-nickel soil

Summary The concentration of nickel in some soils may be insufficient to meet the requirements of enzymes such as urease in soybeans and hydrogenase in Rhizobium. In an initial evaluation of nickel availability, several soils were examined for nickel content and microbial urease activity. Total and extractable nickel were determined by atomic emission spectrometry. Purified glucose and urea were added to soils to stimulate microbial growth and urease activity, the latter of which was monitored by the rate of decomposition of¹⁴C urea. Nickel also was added to some samples to determine if the indigenous supply was limiting. In one low-nickel soil (total Ni 13 ppm) urease activity increased 150% in response to additional nickel, while other soils (total Ni 22–3491 ppm) failed to respond to nickel. However, additional nickel did stimulate urease activity (up to 109%) in 3 out of 10 soils to which purified CaCO₃ was added. Presumably the rise in pH associated with this treatment decreased nickel availability. Additions of Co, Mn, Fe, or Cu had no consistent effect on urease activity, thus indicating that the response to Ni was specific. Nickel fertilization increased leaf urease and nodule hydrogenase activity of soybeans grown in low-nickel soil, however, yield was not improved. These results may have practical implications in the nutrition of plants and micro-organisms that metabolize H₂ and urea.     

Variation in response to heavy metals during vegetative growth in <Emphasis Type="Italic">Dorycnium pentaphyllum</Emphasis> Scop.

Seeds, young plants and adult plants of the perennial Mediterranean leguminous shrub Dorycnium pentaphyllum Scop. were exposed to Cd (1–100 μM) or Zn (10–10,000 μM) on nutrient solution. This species is resistant to Cd and Zn at different phenological stages. The lowest doses of Zn and Cd improved seed germination and young seedling growth, while only the highest doses of both heavy metals inhibited germination and decreased growth. High doses of Cd reduced seed imbibition and young seedling water content, while Zn did not. Osmotic adjustment was more efficient in Zn-treated young plants than in Cd-treated ones, while chlorophyll concentrations decreased in the former but not in the latter. Those differences were not observed anymore in adult plants. Exclusion processes were more efficient at the adult stage than at the young seedling stage and were more marked in response to Zn than to Cd. It is concluded that D. pentaphyllum could be used for phytostabilization of heavy metal-contaminated areas. The physiological strategies of tolerance, however, differ according to the age of the plants and the nature of the metal.     

Evaluation of cadmium,lead and metallothionein contents in the tissues of mussels (Mytilus galloprovincialis) from the Campania coast (Italy): Levels and seasonal trends

The biological effect of seasonality on cadmium, lead and metallothionein contents was assessed in mussels Mytilus galloprovincialis from natural banks located along the coastline of the Gulf of Naples (Campania, Italy). Heavy metals and metallothionein concentrations were measured in digestive and reproductive glands. The results showed a clear correlation between metallothionein content and the reproductive gland status determined during the seasons; on the contrary, no correlation was found between metallothionein and metal contents. Data allow us to hypothesize that metallothionein functions go beyond metal detoxification, thus opening new scenarios for these proteins in invertebrates. The effect of seasons on metals concentration in mussel tissues showed similar seasonal patterns between the sites, regardless of their anthropogenic impacts. Cadmium content was not strictly related to seasonal periods, whereas lead content was significantly lower in summer. The results also indicate that the metal contents in mussels from the Gulf of Naples do not represent a risk to human health, even in the period of their maximum accumulation, and that the relaying of mussels before marketing could improve the animal stress conditions, but having a slight effect on metal excretion.     

Spatial variation of seedling distribution in an east Mediterranean pine woodland at the beginning of post-fire succession

Most of the area in pine woodlands is occupied by perennial seeders that regenerate from seeds in the first winter after the fire and by annuals. Control of the germination in the regenerating vegetation after wildfire is therefore a primary ecological component of the post-fire succession in this ecosystem. The aim of the study presented here was to determine the distribution of Pinus, Cistus and other plants seeds around burned Pinus halepensis trees, and to measure the conditions related to seed germination in the upper soil layers in the same locations. The study was carried out in a 50-year old planted Pinus halepensis woodland that was burned down by a wildfire in July 1995. The variation of seedbank density was determined by collecting samples under the canopies of burned trees and in a nearby open area. Pine seedbank density decreased and that of Cistus and annuals increased with increasing distance from the burned trunks. Most pine seeds were present in the ash layer while those of the other plants were in the soil. In situ germination experiments showed that seedling density decreased with distance from the burned trunks while the proportion of pines in the seedling population increased. This was a result of seedbank variation and germination inhibition by the high pH conditions caused by the ash. The establishment of sparse pine seedling under the dead tree canopies insured their rapid development without interference by other plants and played a key role in the regeneration and stability of the pine woodland community. The concomitant mass germination of the perennial seeders in the rest of the area prevented invasion by annuals.     

Heavy metal concentrations in oak wood growth rings from the Taunus (Federal Republic of Germany) and the Valdivia (Chile) regions

Summary Using a voltammetric procedure described previously, the radial distribution of Cd, Cu, Pb and Zn in annual growth rings of oak from two regions has been investigated: an unpolluted region in Valdivia (Chile) and a polluted region in Königstein (Taunus, FRG). The very low metal levels found in oak wood from the Valdivia region have necessitated that the method be improved and its accuracy tested with standard reference materials and by comparison with electrothermal atomic absorption spectrometry as an independent method. The radial distribution of the four metals investigated is similar in oaks from both regions. No significant differences have been observed in the average concentrations of the essential metals Zn and Cu in the oak tree rings from the two investigated regions. For the toxic metals Cd and Pb, however, a significant increase by a factor of 2 for Cd and by a factor of 12 for Pb has been found when comparing the Königstein and the Valdivia regions. This is evidence of expected pollution of the Königstein region by Pb and, to a lesser extent, by Cd since 1940 or earlier. The trees in both regions can be classified as sound (damage degree 0–1 in Königstein).Attached to the Institute of Chemistry, Universidad del norte, Antofagasta, Chile; material taken in part from Ph. D. Thesis, University of Bonn     

Kinetic properties of a micronutrient transporter from<Emphasis Type="Italic"> Pisum sativum</Emphasis> indicate a primary function in Fe uptake from the soil

Fe uptake in dicotyledonous plants is mediated by a root plasma membrane-bound ferric reductase that reduces extracellular Fe(III)-chelates, releasing Fe²⁺ ions, which are then absorbed via a metal ion transporter. We previously showed that Fe deficiency induces an increased capacity to absorb Fe and other micronutrient and heavy metals such as Zn²⁺ and Cd²⁺ into pea (Pisum sativum L.) roots [Cohen et al. (1998) Plant Physiol 116:1063–1072). To investigate the molecular basis for this phenomenon, an Fe-regulated transporter that is a homologue of the Arabidopsis IRT1 micronutrient transporter was isolated from pea seedlings. This cDNA clone, designated RIT1 for root iron transporter, encodes a 348 amino acid polypeptide with eight putative membrane-spanning domains that is induced under Fe deficiency and can functionally complement yeast mutants defective in high- and low-affinity Fe transport. Chelate buffer techniques were used to control Fe²⁺ in the uptake solution at nanomolar activities representative of those found in the rhizosphere, and radiotracer methodologies were employed to show that RIT1 is a very high-affinity ⁵⁹Fe²⁺ uptake system (K _m =54–93 nM). Additionally, radiotracer (⁶⁵Zn, ¹⁰⁹Cd) flux techniques were used to show that RIT can also mediate a lower affinity Zn and Cd influx (K _m of 4 and 100 M, for Zn²⁺ and Cd²⁺, respectively). These findings suggest that, in typical agricultural soils, RIT1 functions primarily as a high-affinity Fe²⁺ transporter that mediates root Fe acquisition. This is consistent with recent findings with Arabidopsis IRT1 knockout mutants that strongly suggest that this transporter plays a key role in root Fe uptake and nutrition. However, the ability of RIT1 to facilitate Zn and Cd uptake when these metals are present at elevated concentrations suggests that RIT1 may be one pathway for the entry of toxic metals into the food chain. Furthermore, the finding that plant Fe deficiency status may promote heavy metal uptake via increased expression of this transporter could have implications both for human nutrition and also for phytoremediation, the use of terrestrial plants to sequester toxic metals from contaminated soil.     

Nitrogen mineralization in volcanic soil under grassland,shrub and forest vegetation in the Aegean region of Turkey

Summary Net nitrogen mineralization of a grassland-, Quercus coccifera shrub- and Pinus brutia forest-site within the Aegean region was investigated continuously through a year by field and standard incubation methods. Seasonal fluctuations resulting from field incubation are marked in grassland and shrub, but less pronounced in the forest. They are mainly associated with the changes in soil moisture being at minimum in the mediterranean summer. The annual yield of N mineralization is high in grassland and shrub (7.5 and 6.6 h·m^-1), but low in the forest (2.8 g·m^-1), where nitrification is inconspicuous. The reasons for this surprising phenomenon are discussed. N-mineralization is highly elevated in all sites under the favourable conditions of standard incubation (potential mineralization) and the seasonal differences as well as those between the sites are largely diminished.     

Dual augmentation for aerobic bioremediation of MTBE and TCE pollution in heavy metal-contaminated soil

In this work we isolated from soil and characterized several bacterial strains capable of either resisting high concentrations of heavy metals (Cd²⁺ or Hg²⁺ or Pb²⁺) or degrading the common soil and groundwater pollutants MTBE (methyl-tert-butyl ether) or TCE (trichloroethylene). We then used soil microcosms exposed to MTBE (50 mg/l) or TCE (50 mg/l) in the presence of one heavy metal (Cd 10 ppm or Hg 5 ppm or Pb 50 or 100 ppm) and two bacterial isolates at a time, a degrader plus a metal-resistant strain. Some of these two-membered consortia showed degradation efficiencies well higher (49–182% higher) than those expected under the conditions employed, demonstrating the occurrence of a synergetic relationship between the strains used. Our results show the efficacy of the dual augmentation strategy for MTBE and TCE bioremediation in the presence of heavy metals.     

A late Holocene pollen diagram from the Megaris,Greece, giving possible evidence for cultivation of<Emphasis Type="Italic"> Ceratonia siliqua</Emphasis> L. during the last 2000 years

A late Holocene pollen profile from the Megaris on the eastern Gulf of Corinth shows a vegetation which was strongly influenced by human impact throughout. A Pistacia-Phillyrea maquis, which is reflected in the older parts of the profile, changed later to a more degraded vegetation type. In the uppermost part Pinus dominates the pollen spectrum. A continuous record of Ceratonia siliqua pollen older than cal a.d. 100 is of special interest.     

Olea Europea 3-year pollen record in the area of Thessaloniki,Greece and its sensitizing significance

Summary The observations of airborne pollen ofOlea europea and the incidence of clinical manifestations in patients allergic to this pollen type have not been registered so far in the city of Thessaloniki. The purpose of this study was: 1. to assess theO. europea pollen circulation in the area of our city, and 2. to detect the percentage of sensitivity toO. europea pollen in patients with pollinosis. We collected daily pollen samples during a 3-year period (February '87-January '90), using a Burkard volumetric trap, located on a high level area in the centre of the city. The pollen counts were then registered. The O.europea pollen grains were not differentiated microscopically from the other Oleaceae, but identified through phenological criteria. The patients included in the assessment of the sensitivity toO. europea came from the out-patient clinic of bronchial asthma of the General Hospital ?G. Papanicolaou?. They had a seasonal pollinosis and they were submitted to prick test using a battery of 22 groups and an O.europea extract. Pollen ofO. europea appears first in the atmosphere of Thessaloniki at the beginning of May, shows a peak in the end of May and continues to be present till the end of June. The quantity ofO. europea pollen ranked 6th in the list of the total pollen count and its flowering period coincided with that of grasses. In a sample of 360 patients with seasonal pollinosis, we detected anO. europea pollen sensitivity combined with other alleargens in 37% of the patients and a monosensivity in 4%. We conclude that pollen ofO. europea results to be present over a relative short period of time (May–June) in the area of Thessaloniki. The percentage of patients' sensitization toO. europea pollen was a little less frequent than sensitization to grasses, even if their flowering time coincides and their presence in the air shows about the same concentration values.     

Mobilisation of Cu,Mn and Zn in the soil solutions of barley rhizospheres

Summary We report data showing changes during the growing season in the concentrations of manganese, zinc and copper in the rhizosphere in soil solutions of barley plants. Substantial mobilisation of these trace elements occurred during the early stages of rhizosphere development so that soil solution concentrations increased three fold for the copper and zinc and fifteen fold for manganese.