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1.
The paper examines the way in which the term ‘sustainable development’ has been used. Beginning with a short review of responses to a publication of the author's on sustainable development, it goes on to explore the different assumptions behind the discussion of the concept, and the different dimensions of sustainability: economic, political and epistemological. It is argued that, like the environment itself, the concept of sustainable development is a contested domain. We can learn from exploring the way the concept is used and contested.  相似文献   

2.

Using two analytical techniques (ICP‐AES and ASV) the heavy metal pollution of Arge? River was studied. These techniques are characterized by similar analytical performances.

The samples were collected from 13 sites starting from Capra Lake (altitude 2241 m) and finishing at Oltenita city (altitude 10 m).

Arge? River is the fifth longest river in Romania after Siret, Mure?, Olt and Some?, its length is 340 km and the river flows through four cities, Curtea de Arge?, Pite?ti, Gae?ti and Oltenita.

The results of the determinations of Cu, Cd, Zn and Pb, indicate that the Arge? River shows relatively low pollution.  相似文献   

3.
Physiological and biochemical properties of a marine agarolytic association of the bacterium Cytophaga diffluens and the infusorium Uronema marinum were investigated. The agarase activity of the association was shown to be higher than that of the pure bacterial culture at all growth stages under identical conditions. Maximum agarase activity of the association, and of the pure bacterial culture, was observed in a medium containing a small amount of organic nitrogen (0.1% yeast extract). Received: 12 October 1998 / Accepted: 11 June 1999  相似文献   

4.
Education is an established tool to enhance human–environment relationships, despite the lack of empirical evidence to support its use. We used theories of change to unpack assumptions about the role of education in conservation. We interviewed practitioners from 15 conservation organizations in Madagascar to typify implicit pathways of change and assess whether emerging pathways echo theoretical advances. Five pathways were drivers of change: increasing knowledge, changing emotional connection and changing traditional cultural practices, fostering leaders, diversifying outcomes, and influencing community and society. These pathways reflect existing sociopsychological theories on learning and behavioral change. Most interviewees’ organizations had a predominant pathway that was often combined with elements from other pathways. Most pathways lacked culturally grounded approaches. Our research reveals assumptions about the role of education in conservation and indicates that organizations had different ideas of how change happens. The diversity of practices reflects the complexity of factors that influence behavior. Whether this diversity is driven by local sociocultural context, interaction with other conservation approaches, or contingencies remains unclear. Yet, typifying the pathways of change and reflecting on them is the first step towards comprehensive evaluation of when and which pathways and interactions to promote.  相似文献   

5.
A study was conducted on the island of Mahé, Seychelles, on five species of chironomous larvae endemic to the island. The chironomous larvae were exposed to four heavy metals – copper (Cu), cadmium (Cd), mercury (Hg), and zinc (Zn), for a 96-hr period, and the LC50 values were calculated. It was observed that the most sensitive species of chironomous larvae was Gymnometriocnemus mahensis. The least sensitive form of chironomous larvae examined was Paramerina minima. The 96-hr LC50 values obtained for Tanypus complanatus for Cu, Cd, Hg, and Zn were 1.9 (1.73–2.09), 1.35 (1.17–1.57), 0.33 (0.26–0.43), and 28.96 (27.03–31.03) ppm, respectively. Similar results were obtained for other species studied.  相似文献   

6.
Actually, embryos can be cultured from the one‐cell stage up to the blastocyst stage, and their development can be easily monitored at any time: severe effects caused by toxic compounds are traduced by rapid embryonic death, less pronounced effects can be expressed by a lowered cleavage activity or by an arrest of the development from a particular stage. The system can be improved by transferring the embryos at the blastocyst stage in another more complete medium where they can “implant”; and form an inner cell mass with differentiated ectoderm and endoderm. Since last years, it has also become possible to culture postimplantation rodent embryos for short periods involving a number of particularly critical stages of organogenesis, such as the formation and closure of the anterior neuropore. Embryo‐culture also represents a useful system to study cytogenetic effects of chemicals which are often linked to lethal or teratogenic effects. These different possibilities are illustrated by examples of studies already performed with metals, and dealing with their teratogenic and/or cytogenetic effects on pre‐ and postimplantation rodents.  相似文献   

7.
The effects of the ellagic acid on the in vitro and in vivo acetylation of 2‐aminofluorene were investigated in male Sprague‐Dawley rats. For in vitro examination, cytosols with or without ellagic acid co‐treatment showed different percentage of 2‐aminofluorene acetylation. For in vivo examination, pre‐treatment of male rats with ellagic acid (10 mg/kg) 24h prior to the administration of 2‐aminofluorene (50 mg/kg) resulted in a 26% and 29%, respectively, decrease in the urinary and fecal recovery of N‐acetyl‐2‐aminofluorene, and a 37% decrease in the metabolic clearance of 2‐aminofluorene to N‐acetyl‐2‐aminofluorene. This is the first demonstration that ellagic acid decrease the N‐acetylation of carcinogens in vitro and in vivo.  相似文献   

8.
A high-resolution (2-9 year sampling interval) fossil pollen record from the Galápagos Islands, which spans the last 2690 years, reveals considerable ecosystem stability. Vegetation changes associated with independently derived histories of El Ni?o Southern Oscillation variability provided evidence of shifts in the relative abundance of individual species rather than immigration or extinction. Droughts associated with the Medieval Climate Anomaly induced rapid ecological change that was followed by a reversion to the previous state. The paleoecological data suggested nonneutral responses to climatic forcing in this ecosystem prior to the period of human influence. Human impacts on the islands are evident in the record. A marked decline in long-term codominants of the pollen record, Alternanthera and Acalypha, produced a flora without modern analogue before 1930. Intensified animal husbandry after ca. 1930 may have induced the local extinction of Acalypha and Alternanthera. Reductions in populations of grazing animals in the 1970s and 1980s did not result in the return of the native flora, but in invasions by exotic species. After ca. 1970 the trajectory of habitat change accelerated, continuously moving the ecosystem away from the observed range of variability in the previous 2690 years toward a novel ecosystem. The last 40 years of the record also suggest unprecedented transport of lowland pollen to the uplands, consistent with intensified convection and warmer wet seasons.  相似文献   

9.
Many chemicals are in common commercial use for which no information on the environmental fate or toxicity exists. Recent legislation requires that many substances be assessed for their toxicity to aquatic organisms within a very short time and determine which of these chemicals need to be studied in greater detail. It would be impossible to measure the acute and chronic effects of all of these compounds on a single organism, let alone a battery of different types of organisms, communities or ecosystems. Initially, the chemicals on the European Inventory of Existing Commercial Chemical Substances (EINECS) need to be screened and relative hazard to the environment determined. In response to OECD directives, there has been a great deal of activity by government and industry scientists. At the International Workshop on Advances in Environmental Hazard and Risk Assessment it was concluded that quantitative structure activity relationships (QSAR) could and should be used in the hazard assessment process. Papers published in that volume outline the advantages, disadvantages, limitations, advances and research requirements.

The QSAR, structure‐activity based chemical modeling and information system, which was developed by the US‐Environmental Protection Agency was used to predict the acute toxicity of 113 substances from the “Old Substances”; list of the German government to the four commonly used aquatic toxicity test organisms: Daphnia magna (DM), fathead minnow (FHM), rainbow trout (RBT), and blue‐gill sunfish (BG).

Of these compounds the QSAR system predicted the acute toxicity of 87 substances towards fathead minnow. For the other three species examined the QSAR system could be used to predict toxicity for 78 compounds.

The predicted toxicities were compared to observed toxicities of compounds which have been evaluated and stored in the “Aquire”; data base. Observed toxicity values were available for at least one species for 38 compounds. The toxicities of some compounds are well predicted while those of other compounds were not well predicted. Overall, the QSAR system accurately classified the acute toxicity ranges of 50%, 64%, 56% and 56% of the compounds investigated for DM, FHM, RBT and BG, respectively. Of the compounds studied 10 were very poorly predicted, of these the QSAR system overpredicted the toxicity of three, while underpredicting the toxicity of seven. Of these seven compounds, five contained amino groups.  相似文献   

10.
A project promoting the international exchange of information on chlorinated dibenzo‐p‐dioxins and dibenzofurans (CDDs and CDFs) was conducted under the auspices of the Committee on the Challenges of Modern Society (CCMS) of the North Atlantic Treaty Organization (NATO). Initiated in 1985, the Pilot Study on International Information Exchange on Dioxins and Related Compounds was a three‐year effort to improve the state of the art of dioxin research, regulation, and technology by encouraging collaboration among interested countries and organizations. Participating nations included Canada, Denmark, the Federal Republic of Germany, Italy, the Netherlands, Norway, the United Kingdom, and the United States. Numerous activities were accomplished to promote information exchange so that better informed decisions can be made concerning future research activities and resource allocations. Three major areas were addressed: Exposure and Hazard Assessment, Technology Assessment, and Management of Accidents. A total of 15 CCMS reports were published which summarize the achievements of the Pilot Study.  相似文献   

11.
Typically, studies of the disturbance effect on metapopulation dynamics are limited to understanding the effect of habitat loss although, recently, the spatial pattern of the disturbance has been shown to influence dynamics. In this study, we used a stochastic patch-dynamic model to investigate the effects of spatial disturbance patterns on the persistence of an open woodland community of Juniperus spp. and Pinus spp. First, we estimated patch-occupancy dynamics by using the coefficients that best predicted the occupancy observed in 1998 based on occupancy data from 1957. Next, we evaluated the effects of the rate and pattern of the disturbance on the extinction probability. In modeling the disturbance, we considered (1) the degree of disturbance produced by scenarios of complete destruction or degradation (with the potential for recolonization), (2) the overall rate of disturbance, and (3) the spatial autocorrelation of habitat destruction. Twenty 40-year simulations predicted a 25% increase in the number of patches, and when 50% of the habitat was removed, the impact was more pronounced after complete destruction than it was after degradation of the area. Predictions based on scenarios of complete destruction, including random, contiguous, Brownian, and autoregressive noise, demonstrated that the impact of disturbance depends upon the spatial structure of the disturbance regimen. The autocorrelated structure of the disturbance regimen had the greatest impact on patch persistence. Patch-occupancy was higher after 20 40-year simulations when habitat loss was randomly distributed than when it followed an autocorrelated patch destruction, which was simulated using autoregressive noise to produce 50% habitat destruction. In addition, while habitat loss was negatively linearly correlated with patch persistence when habitat destruction was randomly distributed, a dramatic transition shift occurred when habitat destruction was simulated following an autoregressive spatial distribution after a certain threshold of habitat destruction (40% of the actual open woodland habitat). Our study suggests that the spatial patterns of the disturbance should be considered when predicting the consequences of fragmentation and improving management strategies.  相似文献   

12.
The carcinogenicity of metals has received extensive study, both epidemiologically and in the laboratory. These have included case reports of occasional human occurrence or clusters of cancer cases as well as extensive epidemiologic studies; in addition, there has been significant laboratory research on the whole animals and in vitro systems. This body of information will be examined selectively.

I will not in this paper attempt a comprehensive review of the mutagenicity and carcinogenicity of metals and their compounds. Rather, I will attempt to set forth some historical perspectives, and to comment on some current gaps and needs.

Other papers in this workshop have presented thorough and very current reviews of most of the topics briefly noted in this presentation and do not require repetition here.

The cancer issue has been studied and reported on far more extensively than that relating to heritable mutations. There has been in recent years increasing interest in the use of short term tests for mutagenicity and cell transformation. These, however, are primarily with respect to their relationship to cancer production rather than to germ cell injury. Interest in cancer from metal compounds goes back a long time; in fact, one of the earliest reports was on the carcinogenicity of arsenic not many decades after the pioneering report of Sir Perceval Pott on cancer in chimney sweeps. Since then cancer has been definitely associated in humans with chromium compounds, nickel, and with less assurance but probably definitely with beryllium and cadmium. The confirmation of these findings in laboratory animals has been uneven. In the case of arsenic, for example, there has been only limited success in the production of cancer in laboratory animals with arsenic.

Many other metals have been found in laboratory studies to produce cancer, although with most of these, evidence of production of cancer in humans is either absent or extremely uncertain.

The extensive body of recent information relating to the testing of metals with a variety of short term tests will be briefly reviewed.  相似文献   

13.
The solubilization of eight selected substituted indole compounds (SICs) by carboxymethyl‐β‐cyclodextrin (CMCD) in water is reported. The results show that their solubility was well improved in CMCD aqueous solution, and the stoichiometry of inclusion complex of the studied SICs with CMCD was 1: 1. The acute toxicity to Photobacterium phosphoreum of the investigated SICs in CMCD aqueous solutions was also investigated and was compared with that in water. The results show that the toxicity of five studied SICs decreased while the toxicity of the rest three SICs increased in CMCD aqueous solutions, but neither the increase nor the decrease was significant.  相似文献   

14.
The massive expansion in breeding numbers and range of the northern fulmar Fulmarus glacialis over the last two centuries is generally attributed to an increased availability of fish offal and discarded fishes from commercial fisheries. This implies that discards should be a major component in fulmar diets in the more recently colonised areas in the south of their range. This paper examines the contemporary diet of the northern fulmar at three major breeding sites, Fair Isle (Shetland, UK), Iceland and Disko Fjord (western Greenland). At Fair Isle, 89% of regurgitates contained fishes, with sandeels (Ammodytidae) recorded in 37%; 32% contained crustaceans (mainly decapods); 8% contained squid. There was also a temporal trend; sandeels declining and crustaceans increasing in the diet from July to August. In Iceland, fishes were also the main prey (47 to 93% of wet mass), with sandeels common in the south and west, and capelin (Mallotus villosus) in the north and east. Other fish species were mainly discards, and together with discarded decapods and fish offal formed 5 to 72% of the diet, depending on the sector. Euphausiids, amphipods and copepods constituted 3 to 13% of the diet. At Disko, 39% of samples contained fishes, 64% contained crustaceans (mainly amphipods), 22% contained squid, and 16% contained pteropods. There was a clear temporal trend, with the bulk of the samples made up of crustaceans in mid-June, capelin from late June to late July, and crustaceans and pteropods from late July to late August. An extensive review of published studies was also carried out. The general pattern was for birds in more southerly populations to consume more discarded fishes, fish offal and benthic invertebrates. However, a considerable proportion of their diet also consisted of juvenile gadids, sandeels, capelin and pelagic zooplankton, which fulmars catch for themselves, and we suggest that breeding adults in the south are less dependent on fishing waste than is generally assumed. Received: 25 September 1998 / Accepted: 7 May 1999  相似文献   

15.
Thyroid dysfunction during pregnancy has been shown to be associated with adverse pregnancy outcomes. Consequently, this study was undertaken to assess the thyroid health of the pregnant females in the United States. Publically available data from National Health and Nutrition Examination Survey for the cycles 1999–2002 and 2007–2012 were analyzed for this purpose. Over 22% (SE: 5.7%) of the pregnant females based on the unweighted data in their first trimester had higher than the recommended levels of thyroid-stimulating hormone (TSH) or 2.5 mIU/L. Free triiodothyronine (FT3) and free thyroxine (FT4) levels decreased over pregnancy trimesters. Based on unweighted data, about 6% (SE: 2.6%) pregnant females were positive for thyroglobulin antibodies and 34.9% (SE: 5.2%) pregnant females were positive for thyroid peroxidase antibodies. Over 55% (SE: 3.5%) pregnant females based on the unweighted data were iodine deficient. As many as 41% (SE: 3%) first trimester pregnant females having TSH > 2.5 mIU/L is of concern. Future research should concentrate on developing educational and other materials that can advise pregnant females during their prenatal care and other appointments about the adverse effects of high TSH levels and what they can do to keep their TSH levels within the recommended levels.  相似文献   

16.
Spatial distributions of sand beach arthropods were studied at Zouara (Nefza), a beach dune system along the northwestern coast of Tunisia. Two transects with pitfall traps, perpendicular to the shoreline and placed from sea towards land, captured spontaneously crawling arthropods. The pitfalls were used to obtain data on horizontal zonations for 2 days during different seasons (April, October). In April, in order to assess local, long-shore distributions of surface-active beach invertebrates, ten transects with pitfall traps were placed every 100 m, for 2 days. Core samples were also taken in correspondence with each of the ten transects to obtain the distribution of burrowing individuals. Sand samples were taken for successive laboratory analyses (salinity, grain size and organic contents). Local climatic conditions were also recorded. One isopod (Tylos europaeus, subdivided into three different size classes), two amphipods (Talitrus saltator, Talorchestia brito and indistinguishable juveniles) and four coleopteran species (Eurynebria complanata, Scarites laevigatus, Phytosus nigriventris, Phaleria acuminata) were considered. Mean zonations perpendicular to the shoreline showed that crustaceans were found closer to the sea-line limits than coleopterans and that between seasons some species changed their mean zonation more than others. Local, long-shore distributions of active and burrowing individuals showed that most species were unevenly distributed along the shore. These discontinuous distributions differed according to the species and age class and were mainly related to specific microclimatic conditions and to nutrition.  相似文献   

17.
In order to reveal the distribution pattern and spatial correlation of Pinus tabulaeformis population, this research used geostatistical theory and methods to examine the distribution pattern and spatial correlation of P. tabulaeformis population in different habitats of the Lingkong Mountain. The results showed that the semivariograms well fitted the exponential model for P. tabulaeformis populations at the mountain ridge, and the spherical model for those in slow slopes and valley areas. All three populations showed aggregated pattern. The spatial heterogeneity of the habitats of ridge, slow slope and valley was mostly due to the spatial autocorrelation in the ranges of 11.16 m, 9.99 m and 4.74 m, respectively. The populations at the ridges and gentle slopes showed greater sill values and determinant coefficient but lower fractal dimension than the pines in valleys, indicating that the first two habitats are characterized by higher degree of spatial heterogeneity and more significant spatial patterns, which is not found in the valley populations. Therefore the variations in the spatial distribution patterns of P. tabulaeformis populations is likely resulted from both the intrinsic biological characteristics and the environmental factors.  相似文献   

18.
The current study represents a preliminary investigation made into the influence of cattle grazing in the area of a bauxite quarry (Comarnic–Poieni, Romania) on the cow milk chemistry. Weathering and surface runoff in the bauxite quarry contaminate the local chemistry of the soil, vegetation and water. During cattle transhumance, cyclic feeding patterns occur, with grazing alternating between clean pastures and the area of the quarry. Soil and water samples were collected from the contaminated area of the quarry. Raw milk samples were collected during two stages, corresponding to the periods of grazing on clean pasture and the quarry area, respectively. Based on the obtained data, the relationship between cattle grazing and the composition of milk was interpreted. Preliminary results indicated a direct correlation of increased concentration of Al in the milk, following grazing in the bauxite quarry.  相似文献   

19.
• A two-compartment model is able to quantify the effect of nano-TiO2 on Pb toxicity. • Nano-TiO2 reduces Pb tolerance level and increased the killing rate for C. dubia. • Thus, nano-TiO2 synergistically enhances Pb toxicity. • Algae reduce Pb transfer rate to the body tissue and the killing rate. Nano-TiO2 can remarkably increase lead (Pb) toxicity in aquatic organisms. However, the mechanism of this toxicity, additive or synergistic, is not well understood. To explore this mechanism, we inspected the role of nano-TiO2 in the toxicity of Pb on Ceriodaphnia dubia (C. dubia), a model water flea species typically used for ecotoxicity studies. The effect of algae, a diet for aquatic organisms, on the effect of this binary mixture was also investigated. A two-compartment toxicokinetic (TK)-toxicodynamic (TD) modeling approach was used to quantify the Pb toxicity under these complex conditions and to develop critical parameters for understanding the mechanism of toxicity. This two-compartment modeling approach adequately described the Pb accumulation in the gut and in the rest of the body tissue under different nano-TiO2 concentrations, with and without algae, and predicted the toxicity response of C. dubia. It indicated that increasing the nano-TiO2 concentration reduced the Pb tolerance level and concurrently increased the killing rate constant of C. dubia. Therefore, nano-TiO2 synergistically enhanced Pb toxicity. Algae remarkably reduced the toxicity of this binary mixture through reducing the Pb transfer rate to the body tissue and the killing rate, although it did not affect the Pb tolerance level. This two-compartment modeling approach is useful in understanding the role of nanoparticles when assessing the overall toxicity of nanoparticles and other toxic elements in the environment.  相似文献   

20.
Humpback whales (Megaptera novaeangliae) in the Southeastern Atlantic Ocean (International Whaling Commission ‘Breeding Stock B’—BSB) are distributed from the Gulf of Guinea to Western South Africa. Genetic data suggest that this stock may be sub-structured, but it remains unknown if this is due to reproductive segregation. This paper evaluates the spatial and temporal population structure of BSB humpback whales using a combination of maternally and bi-parentally inherited markers. The genetic differentiation that we identify in this study could be due to a combination of (1) spatial and/or temporal segregation on breeding grounds in the greater Gulf of Guinea, (2) the possibility of maternally inherited site fidelity to specific feeding grounds and (3) the use of two generalized but exclusive migratory routes (coastal and offshore) between feeding and breeding areas. Further, photo-identification and genetic sampling efforts in other areas of the Sub-Saharan Western Africa winter range and targeted deployment of satellite tags would help to clarify some of the apparent complexity in the population structure of animals biopsied in this region.  相似文献   

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