Several hypotheses have been proposed to explain the mechanisms responsible for maintenance of host-specific gentes in the common cuckoo (Cuculus canorus). Some of them expect that when adult cuckoos return to lay their eggs to their natal site (natal philopatry hypothesis) or habitat in which they were reared (habitat-imprinting hypothesis), there is a higher probability of finding nests of the host species by which they were reared. Since published evidence is ambiguous, we here evaluate the natal philopatry and habitat-imprinting hypotheses using information on habitat homogeneity and cross-continental long-term ringing data. We found no evidence for the natal philopatry hypothesis—instead of returning to their natal site, juvenile cuckoos exhibited longer dispersal movements than adults, and the difference was even larger in comparison with a wide array of cuckoo host species. On the contrary, we found support for the habitat-imprinting hypothesis—juvenile cuckoos followed similar levels of natal habitat homogeneity at 5- and 25-km scale when returning to breed in the next years. Our results suggest that preference for the particular habitat structures may help cuckoos to find appropriate hosts.
Many marine organisms inherently express the presence and function of a new defence mechanism, termed multixenobiotic resistance mechanism (MXRM) because of its similarity to multidrug resistance (MDR) found in tumor cell lines resistant to chemotherapeutic drugs. However, previously no information was available on a possible induction of the activity of MXRM in organisms living at polluted sites. The purpose of the present study was to demonstrate the inducibility of this defence mechanism in the marine snail Monodonta turbinata, an organism known to inhabit a wide range of environmental conditions existing along a pollution gradient. Specimens of M. turbinata used in the present study were collected from March 1993 through March 1994 near Rovinj, Croatia. The accumulation of generally labelled 3H-vincristine (3H-VCR) in the gills of snails living at an unpolluted site was 67% higher and very sensitive to verapamil, an inhibitor of P-glycoprotein activity in comparison to snails living at a polluted site. The accumulation of vincristine (VCR) in snails from a polluted site was reduced and insensitive to verapamil due to the induced state of P-glycoprotein, as was demonstrated immunochemically by the enhanced concentration of a 140 kDa protein cross-reacting with the polyclonal antibodies raised against mammalian P-glycoprotein. MXRM could be induced in snails from the unpolluted site to the level found in snails living at a polluted site either by transplantation for 3 d to a polluted site, or by exposure for 3 d to sea water polluted with Diesel-2 oil (hydrocarbon concentration equivalent to 50 ppb of Kuwait oil). Discovery of the inducibility of this new defence mechanism in aquatic organisms may have important implications in ecotoxicology, as was demonstrated by a 104% enhanced accumulation of VCR in the presence of the MXRM-inhibitor, the so-called chemosensitizer. Besides, a striking difference in the levels of MXRM-elements (the sensitivity of the accumulation rate of xenobiotics to verapamil, immunochemical expression of P-glycoprotein, and the sensitivity of the binding of xenobiotics on membrane vesicles to verapamil) found between specimens living at the polluted and unpolluted sites offers a new molecular biomarker for exposure to pollutants. 相似文献
Summary Croatia, as a Mediterranean country in the south-eastern part of Europe, is an area with a characteristic flora and fauna. The ornithofauna of Croatia reflects that it is a breeding area for some of the globally endangered bird species, as well as a site for the spring/autumn passage and the wintering of European migratory birds. Many ornithologically significant localities are designated and there are 20 ornithological reserves and four wetland sites that are on the list of the Ramsar Convention.In Croatia, there are four governmental organizations dealing with scientific research on birds of which the Institute for Ornithology of the Croatian Academy, of Sciences and Arts is that with the longest tradition. There are also many non-governmental organizations dedicated to the protection of environment, but only the Croatian Society for Bird and Nature Protection is dedicated mostly to bird protection. There are not many sources of funding for research and the protection of birds; the chief source being the Ministry of Sciences and Technology of the Republic of Croatia.Croatia has to establish new legislation according to European criteria and The Hunting Law, The Nature Protection Law and The Environment Protection Law have been recently accepted in Parliament. International Conventions, such as Bern, Bonn and Washington, have yet to be adopted. Foreign, hunting tourism, especially organized by fishpond authorities, is believed to be killing large numbers of protected water birds. A red data book exists only for plants and mammals and this makes biological assessments difficult.With the end of military operations and the reintegration of the occupied areas of Croatia, an assessment of the damage to the national parks and nature reserves, and to nature in general, will be necessary. Bird and nature conservation in Croatia remains promising, provided the legal control of the Croatian government over the occupied parts of the country is restored soon and international organizations give assistance.Dr Jasmina Muini is Croatian by birth and she has studied in Paris, Oslo, and Zagred where she gained her PhD. She is a President of the Croatian Society for Bird and Nature Protection, a member of the Croatian Parliament Board for Environmental Protection, vice-president of the Scientific Council of the Zoological Garden in Zagreb, and a member of other Croatian environmental bodies. She is a leading authority on the ornithofauna of the Croatian wetlands. 相似文献
The purpose of this study was to monitor and record the specific characteristics and properties of most of the important water resources in Dalmatia located in Southern Croatia for a period of 5 years (1998–2002) according to established standards for drinking water. The paper presents a detailed account of their chemical content, the classification and the concentration of salts. The bacteriological pollution levels are indicated by the total coliform bacterial levels (MPN coli/100 mL). The water characteristics are expressed by coefficients, which represent the ratios between water ingredients. The Ca/Mg eq ratio, SO4/Cl eq ratio and K1, K2 for bicarbonate hardness were calculated. The hygienic characteristics of the water samples were expressed by the total coliform bacteria estimation (MPN coli/100 mL), the permanganate consumption (KMnO4) and biological oxygen demand (BOD5). Karst waters in Dalmatia are moderately hard, the SO4/Cl ratio is 0.38–1.6, non-corrosive (K1 lower than 0.2) and not significantly mineralised (< 500 mg/L minerals). Sulphate waters are generally hard, the SO4/Cl ratio is higher than 1.6, K1 is 0.2–0.65. Marine waters are quite hard or hard, particularly at the river estuaries, the SO4/Cl ratio is lower than 0.38, and K1 is higher than 0.65. The groundwater and springs in Dalmatia are less polluted than surface waters. A majority of these have a geometric average value of MPN coli < 150/100 mL of water observed in 24 of 42 locations studied. The highest bacteriological pollution was found in nine locations where MPN coli > 1000/100 mL and moderate pollution was found in nine locations where MPN coli is between 150 and 1000/100 mL of water. The physical and chemical parameters determined for the most sources in Dalmatia are safe below the international permissible limits. 相似文献
This paper describes the use of epiphytic lichens as bioindicators for spatial monitoring of mercury and other elements in air near the natural gas treatment facilities at Molve, Croatia. It is well known that at this location the concentration of mercury in natural gas is very high and therefore it has to be removed from natural gas before further processing in order to prevent technological and environmental problems. In order to monitor the efficiency of an industrial facility for removal of mercury from natural gas, mercury measurements in air and lichens were performed during 9 months in 1997/1998. In situ lichens Parmelia sulcata, Xantoria parientina and Hypogymnia physodes and transplanted lichen species Hypogymnia physodes were used. A good correlation between mercury concentrations in air and lichens was found. The concentrations of barium and bromium were also significantly elevated in transplanted lichens, most probably related to technological process at the gas treatment plant and/or other geological factors. It was confirmed that lichens can successfully be used as bioindicators, provided a careful experiment is designed, particularly the amount of lichens transplanted, the duration of exposure and the initial levels and homogeneity of transplanted lichens. 相似文献
The objective of this study was to develop an integrated geographic information system (GIS) cellular automata (CA) model
for simulating insect-induced tree mortality patterns in order to evaluate the influence of different forest management activities
to control insect outbreaks. High-resolution multispectral images were used to determine susceptibility of trees to attack,
whereas the GIS-based CA model simulated the effectiveness of clear-cuts and thinning practices for reducing insect-induced
tree mortality. The results indicate that thinning susceptible forests should be more effective than clear-cutting for reducing
tree loss to insect outbreaks. This study demonstrates the benefits of an integrated approach for understanding and evaluating
forest management activities and expresses the need for spatial analysis and modeling for improving forest management practices. 相似文献
The concept of multiple separation by chemisorptive filters was applied and investigated in the process of arsenic removal from water. Chemisorption filters were made by the paper manufacturing method and consisted of cellulose, cationic and anionic ion exchangers, activated carbon and a corresponding chemical agent. In this work chemisorption filters were activated with Ag+, Mg2+, Cu2+, Al3+ and Fe3+ ions, and their chemical contribution to total arsenic removal from the water was analyzed. It was concluded that Cu2+ ions exhibited the best removal effect. Using a chromatographic continuous system with multifunctional filters, which combines the effects of adsorption, ion exchange and filtration, a decrease in the arsenic concentration was determined; for an active layer of 8 mm and a contact time of 2 s it was more than 1000-fold. All processes were performed in batch and chromatographic continuous systems under equilibrium or dynamic conditions. The results of the investigations have shown that arsenic removal is valence dependent (the removal of pentavalent arsenic was more effective). The initial concentration, pH and pollutants in anionic forms, which affected the selectivity, were important for all the processes investigated. The mechanisms of pollutant removal were determined on the basis of measurements of active Cu2+ ion propagation inside the filter structure. By correlating the front propagation of active ions and the pollutant output concentration a more exact model for the removal process was obtained. 相似文献
Saturated water solutions of calcium chloride, calcium bromide and their 1:1 mixture are commonly used as "high density brines" for pressure control in oil wells. To compare the effect of these chemicals of technical grade with the effect of the chemicals of analytical grade the Lemna test was used. The multiplication rate, fresh weight, dry to fresh weight ratio, area covered by plants and chlorophyll content were measured as toxicity parameters. The concentrations of tested chemicals were 0.025, 0.05. 0.075 and 0.1 mol dm(-3). Generally, the chemicals of both technical and analytical grade in concentrations of 0.025 mol dm(-3) stimulated the Lemna minor growth, while tested chemicals in concentrations of 0.05 mol dm(-3) did not affect the growth significantly. The exceptions were results obtained by measuring fresh weight. Most of tested chemicals in concentrations of 0.075 mol dm(-3) and all chemicals in concentrations of 0.1 mol dm(-3) reduced the growth. No major differences between effects of tested chemicals of technical and analytical grade on plant growth were observed, except that tested chemicals of analytical grade in concentrations of 0.1 mol dm(-3) increased dry to fresh weight ratio much stronger than chemicals of technical grade. All tested chemicals in all concentrations increased chlorophyll content. After treatment with chemicals of analytical grade much higher increase of chlorophyll a concentration in comparison to increase of chlorophyll b was noticed, while chemicals of technical grade caused more prominent increase of chlorophyll b. 相似文献
Background, Aims and Scope In oil spill investigations, one of the most important steps is a proper choice of approaches that imply an investigation
of samples taken from different sedimentary environments, samples of oil contaminants taken in different periods of time and
samples taken at different distances from the oil spill. In all these cases, conclusion on the influence of the environment,
microorganisms or migration on the oil contaminants' composition can be drawn from the comparison of chemical compositions
of the investigated contaminants. However, in case of water contaminants, it is very important to define which part of organic
matter has been analyzed. Namely, previous investigations showed that there were some differences in chemical composition
of the same oil contaminant depending on the intensity of its contact with ground water. The aim of this work is to define
more precisely the interactions between oil contaminant and water, i.e. the influence of the intensity of interaction between
the oil contaminant and water on its chemical composition. The study was based on a comparison of four fractionated extracts
of an oil pollutant, after they had been analyzed in details.
Methods Oil polluted surface water (wastewater canal, Pančevo, Serbia) was investigated. The study was based on a comparison of four
extracts of an oil contaminant: extract 1 (decanted part), and extracts 2, 3 and 4 (extracted by shaking for 1 minute, 5 minutes
and 24 hours, respectively). The fractionated extracts were saponified with a solution of KOH in methanol, and neutralized
with 10% hydrochloric acid. The products were dissolved in a mixture of dichloromethane and hexane, and individually fractionated
by column chromatography on alumina and silica gel (saturated hydrocarbon, aromatic, alcohol and fatty acid fractions). n-Alkanes
and isoprenoid aliphatic alkanes, polycyclic alkanes of sterane and triterpane types, alcohols and fatty acids were analyzed
using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). δ13CPDB values of individual n-alkanes in
the aliphatic fractions were determined using gas chromatography-isotope ratio monitoring-mass spectrometry (GC-irmMS).
Results and discussion. Extracts 1 and 2 are characterized by uniform distribution of n-alkanes, whereas extract 3 is characterized
by an even-numbered members dominating the odd-ones, and extract 4 showed a bimodal distribution. Extract 1 is characterized
by the least negative δ13CPDB values of C19-C26 n-alkanes. Sterane and triterpane analysis confirmed that all extracts originated
from the same oil contaminant. n-Fatty acids, C19-C24, in all extracts are very low, being somewhat higher in extract 4. Even-numbered
n-alcohols, C12–C16, were identified in the highest concentration in extract 3. It was assumed that algae were responsible
for the composition of extract 3. Furthermore, a possible reason for higher concentrations of C19–C26 n-alkanes and C19–C24
fatty acids in extract 4 is the formation of inclusion compounds with colloidal micelles formed between the oil contaminant's
NSO-compounds and water.
Conclusion It was undoubtedly confirmed that there were specific differences in the compositions of the different extracts depending
on the intensity of the interaction between the oil contaminant and the surface water.
Recommendation and Outlook. When comparing the composition of oil contaminants from different water samples (regardless of
the ultimate investigation goal) it is necessary to compare the extracts isolated under the same conditions, in other words,
extracts that were in the same or very similar interaction with water. 相似文献
INTENTION, GOAL, SCOPE, BACKGROUND: As the strong negative health effect of exposure to the inhalable particulate matter PM10 in the urban environment has been confirmed, the study of the mass concentrations, physico-chemical characteristics, sources, as well as spatial and temporal variation of atmospheric aerosol particles becomes very important. OBJECTIVE: This work is a pilot study to assess the concentration level of ambient suspended particulate matter, with an aerodynamic diameter of less than 10 microm, in the Belgrade central urban area. Average daily concentrations of PM10 and PM2.5 have been measured at three representative points in the city between June 2002 and December 2002. The influence of meteorological parameters on PM10 and PM2.5 concentrations was analyzed, and possible pollution sources were identified. METHODS: Suspended particles were collected on Pure Teflon filters by using a Mini-Vol low-volume air sampler (Airmetrics Co., Inc.; 5 l min(-1) flow rate). Particle mass was determined gravimetrically after 48 h of conditioning in a desiccator, in a Class 100 clean room at the temperature T = 20 degrees C and at about 50% constant relative humidity (RH). RESULTS AND DISCUSSION: Analysis of the PM10 data indicated a marked difference between season without heating--(summer; mean value 56 microg m(-3)) and heating season--(winter; mean value 96 microg m3); 62% of samples exceeded the level of 50 microg m(-3). The impact of meteorological factors on PM concentrations was not immediately apparent, but there was a significant negative correlation with the wind speed. CONCLUSIONS: The PM10 and PM2.5 mass concentrations in the Belgrade urban area had high average values (77 microg m(-3) and 61 microg m(-3)) in comparison with other European cities. The main sources of particulate matter were traffic emission, road dust resuspension, and individual heating emissions. When the air masses are coming from the SW direction, the contribution from the Obrenovac power plants is evident. During days of exceptionally severe pollution, in both summer and winter periods, high production of secondary aerosols occurred, as can be seen from an increase in PM2.5 in respect to PM10 mass concentration. RECOMMENDATION AND OUTLOOK: The results obtained gave us the first impression of the concentration level of particulate matter, with an aerodynamic diameter of less than 10 microm, in the Belgrade ambient air. Due to measured high PM mass concentrations, it is obvious that it would be very difficult to meet the EU standards (EEC 1999) by 2010. It is necessary to continue with PM10 and PM2.5 sampling; and after comprehensive analysis which includes the results of chemical and physical characterization of particles, we will be able to recommend effective control measures in order to improve air quality in Belgrade. 相似文献