Acid dissolution methods for heavy metals determination in pine needles

Microwave digestion procedures using HNO₃, HNO₃+H₂O₂, HNO₃+HClO₄, HF mixtures and dry ashing with HF were investigated for heavy metals analysis by either inductively coupled plasma-optical emission spectroscopy (ICP-OES) or ICP-mass spectrometry (ICP-MS) in pine needles. The HF digestion procedures gave about 1.5 times higher values than a mixture of HNO₃+H₂O₂ alone. For Ti determination in needles, the HF procedure using dry ashing is thus recommended. The mean concentrations amounted to 900 mg/kg for Fe and 21.8 mg/kg for Ti in needles collected at an area polluted by a stainless steel works. Those concentrations were 10.6 and 4.3 times higher than in needles collected at an area nearby a pulp mill complex (84.5 mg/kg Fe and 5.0 mg/kg Ti).     

Microphytoplankton in the Strait of Otranto (eastern Mediterranean)

The Strait of Otranto is the connection between the Adriatic and Ionian Seas. Low nutrient concentrations, high transparency, and low phytoplankton cell density and biomass reflect the oligotrophic character of the area. Enrichment of the euphotic layer with nutrients is mainly due to discharge of Albanian and Greek rivers, as well as mixing and upwelling in winter/early spring. Following phytoplankton bloom in April, a progressive decrease of phytoplankton cell density is due to the consumption of nutrients throughout the proceeding summer and autumn. Nitrogen was a strong limiting factor for phytoplankton growth in summer. Deep biomass maxima were detected in the 50 to 100 m layer and corresponded mostly to cells smaller than 20 m. The eastern part of the strait is mostly influenced by the northerly inflowing current from the Ionian Sea, and the western part by the southerly outflowing current from the Adriatic Sea. This typical circulation could be disturbed by inertial oscillations in the current field, generated by the strong oscillating winds and cyclonic eddies. The type of circulation determined the distribution of thermohaline characteristics, abundance, biomass, as well as taxonomic composition of phytoplankton, across the strait. Ecological characteristics of the water masses on two sides of the strait were significantly different during the formation of a longitudinal thermohaline front in May 1990.     

Mate sampling behaviour of black grouse females (Tetrao tetrix)

We studied female mate sampling behaviour in lekking black grouse (Tetrao tetrix). Females mainly visited males occupying territories in the centre of the lek with relatively large territories. They were also more likely to visit males that had high attendance. The same factors were also correlated with male mating success. A multiple regression model including these factors explained more of the variance in female visits per male (53%) than in mating success (33%). The pattern of female sampling conformed with a pool comparison (best-of-n) tactic. Such a tactic is expected if the costs of sampling are low. Females of high body mass visited more males than lighter females, however, which indicates that females may vary in their search tactics and suggests that there may be search costs. The existence of costs is further suggested by the fact that if the mate from a previous year was still present, females always mated with the same male in the following year. Though search costs were not measured directly, our findings suggest that some costs are negligible (e.g. energetic exhaustion or predation) whereas others (timing of mating) may be more important.     

Composition and temporal fluctuations of inshore juvenile fish populations in the Kornati Archipelago, eastern middle Adriatic

Temporal fluctuations of species composition and abundance of fish juveniles in the National Park Kornati were studied over 12 months from January to December 1992. A total of 40 168 individuals, representing 24 families and 69 species, were collected using a 50 m long beach seine. The community was dominated numerically by a few species: Atherina hepsetus (45.90%), Sarpa salpa (21.21%), Diplodus vulgaris (10.49%), and Symphodus ocellatus (6.98%), constituting over 84.58% of the total catch. Similarity between patterns in the abundance of the 17 most common species were examined using correlation matrix-based principal component analysis. Results were compared to the abiotic factors leading to the conclusion that only a low amount of variation in the abundance field can be explained by temperature, salinity and dissolved oxygen. Received: 23 March 1997 / Accepted: 11 April 1997     

Delayed maturation in plumage colour: Evidence for the female-mimicry hypothesis in the kestrel

Summary In many sexually dichromatic species, young males have female-like plumage during their first potential breeding year. The female-mimicry hypothesis (FMH) supposes that by possessing female-like plumage young males deceive older conspicuous males into believing that they are females, thus reducing competition from adult males. The status-signalling hypothesis (SSH) supposes that adult males can distinguish sex, but postulates that young males reduce competition from adult males by reliably signaling low status with their dull plumage. We tested these hypotheses in the European kestrel (Falco tinnunculus). Female-like young males settled to breed closer to adult males than did other adult males (Figs. 1a, b). By settling near adult males, young males seemed to increase their chance of mating with adult females. Adult female-young male pairs had better reproductive success than yearling-yearling pairs. These results suggest that there is an adaptive value in possessing a female-like plumage colour in the breeding season. To test the FMH, we measured sexual preference of adult males when adult females and young males were simultaneously shown in an aviary. Adult males were unable to recognize sex, because in half the cases they preferred young males (Fig. 3). However, when adult males and females were shown simultaneously, males preferred females (Fig. 2). Our results support the FMH rather than the SSH, because young males successfully deceived older males by their plumage.     

Effect of nitrogenous air pollutants on changes in protein spectra with the onset of winter in the leaves and shoots of the bilberry (Vaccinium myrtillus L.)

Electrophoretic profiles of 0.1 m Tris-HCl (pH 9.0)-soluble proteins in the leaves and stems of the bilberry (Vaccinium myrtillus L.) were investigated in the latter part of the growing season (July-October), in a highly-polluted industrial area with serious forest damage (main emissions NO(2), SO(2), NH(3), urea and fertilizer dust) in Oulu, northern Finland, and in an unpolluted control forest with the same climatic and edaphic conditions. About ten protein components in the leaves and seven in the stems increased in concentration in SDS-PAGE towards the autumn, while one to four other components decreased in concentration. The pollutants in the industrial area caused a considerable decrease in the concentrations of soluble proteins, particularly in the leaves in August and September. A decrease was obtained in six components in the leaves and three components in the stems, while increases were observed in one component in the leaves (10 kDa) and four components in the stems (10, 43, 50 and 65 kDa). One reason for the lowered cold-resistance in the bilberry caused by air pollutants could thus be the lowered concentrations of certain soluble cytoplasmic proteins that protect the plant against winter conditions.     

The use of a sequential leaching procedure for heavy metal fractionation in green liquor dregs from a causticizing process at a pulp mill

A five-stage sequential leaching procedure was used to fractionate heavy metals (Cd, Cu, Pb, Cr, Zn, Fe, Mn, Ni, Co, As, V, Ba and Ti) in green liquor dregs into the following fractions: (1) water-soluble fraction (H2O), (2) exchangeable fraction (CH3COOH), (3) easily reduced fraction (HONH3Cl), (4) oxidizable fraction (H2O2 + CH3COONH4), and (5) residual fraction (HF + HNO3 + HCl). The green liquor dregs were derived from a causticizing process at a pulp mill at Kemi, Northern Finland. According to the leaching studies, the leachability of heavy metals in the water-soluble fraction varied between 0.5 and 2 mg kg(-1) expressed on a dry weight (d.w.) basis, indicating relatively low bioavailability of the metals. However, the concentration of Mn (2065 mg kg(-1); d.w.) showed a strong and of Zn (17.6 mg kg(-1); d.w.), Ni (39.7 mg kg(-1); d.w.) and Ba (32.0 mg kg(-1); d.w.) slightly tendency to be extracted in the exchangeable fraction. In addition, Zn, Mn, Ni, Co, V and Ba showed clear leachability in the easily reduced fraction, as well as Cd, Cu, Cr, Zn, Mn, As and Ba in the oxidizable fraction. For Cd, Cu, Cr, Zn, Mn, Ni, Co, Ba and Ti, the sum of leachable heavy metal concentrations in fractions 1-5 agreed relatively well with the "total" heavy metal concentrations. Recoveries of the sum of fractions 1-5 were 84-56% of those obtained by the US EPA method 3052 (i.e. concentrations obtained after microwave oven digestion with a mixture of HF and HNO3).     

Levels of DDT and PCB's in different stages of life cycle of the Arctic tern Sterna paradisaea and the herring gull Larus argentatus

∑DDT and PCB levels were analysed in samples of arctic terns and herring gulls collected in the archipelago of southwestern Finland. Special attention was paid to the levels at various stages of the life cycle and in different sexes. The levels were nearly ten times higher in the herring gull. The highest loads were found in adult birds and in newly hatched chicks but the levels were much lower (only 7–12 % in the herring gull) in chicks just before fledgling. The levels in young gulls remained low until the end of August at least. Therefore it is plausible that the high levels found in adult gulls are a consequence of their wintering in the southern Baltic.The levels of ∑DDT and PCB residues were significantly lower in female arctic terns than in male terns. Differences between the sexes were small in the herring gull. Thus it is possible that the female of the arctic tern is able to release pollutants, especially PCB residues, more effectively into eggs than the female of the herring gull. The biochemical mechanisms involved are not clear but a possible explanation may be different lipoprotein structures in the eggs of the species.     

Limited scope for reproductive senescence in wild populations of a short-lived fish

Senescence in wild populations was long considered negligible but current evidence suggests that it is widespread in natural populations of mammals and birds, affecting the survival and reproductive output of older individuals. In contrast, little is known about reproductive senescence in species with asymptotic growth that can keep increasing their reproductive output as they grow older and larger. Using a cross-sectional study, we tested age-related decline in fecundity and relative allocation to reproduction in five wild populations of an annual killifish, Nothobranchius furzeri (Cyprinodontiformes). We did not detect any decline in absolute female egg production over their short lifespan in the wild. Relative fecundity (egg production controlled for female body mass) tended to decrease with age. This effect was driven primarily by a single population that survived 17 weeks, almost twice as long as the median persistence of the other four study populations. There was no decrease in relative ovary mass while in males, relative testes mass actually increased with age. Intra-population variation in relative ovary mass increased in older females suggesting heterogeneity in individual trajectories of female reproductive allocation. Overall, we demonstrate that annual killifish do not experience significant age-related decline in reproductive functions during their very short lifespan in the wild despite the marked deterioration of gonad tissue detected in captivity.