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561.
As some species of game and free‐living animals promptly respond to ecosystem damage by a reaction that is easy to interpret, they are important ecological indicators in assessing the total contamination of the environment. Consumers of the highest order like predators, predatory and fish‐eating birds are among the most important bioindicators of environmental contamination by chlorinated hydrocarbons and PCB.

Data on chlorinated hydrocarbons and PCB levels were collected throughout 1988–1992 and obtained from 16 species of free‐living animals from 9 protected areas of Slovakia. Muscle tissue, liver, kidney and egg samples were examined for HCB, HCH isomers, DDT and its analogues, and PCB.

Levels of organic chlorinated contaminants reveal a decreasing tendency and thus cease to be a toxicologically important risk factor in game, with the exception of predatory birds, as significant values have been recorded in their eggs and reproductive organs.  相似文献   
562.
This paper describes how organic compounds and nitrogen compounds induce the formation of hydrogen cyanide during the distillation process. Hydrogen cyanide formation was confirmed by X‐ray diffraction. The formation scheme for hydrogen cyanide from organic compounds is proposed.  相似文献   
563.
Conservation operates within complex systems with incomplete knowledge of the system and the interventions utilized. This frequently results in the inability to find generally applicable methods to alleviate threats to Earth's vanishing wildlife. One approach used in medicine and the social sciences has been to develop a deeper understanding of positive outliers. Where such outliers share similar characteristics, they may be considered exceptional responders. We devised a 4‐step framework for identifying exceptional responders in conservation: identification of the study system, identification of the response structure, identification of the threshold for exceptionalism, and identification of commonalities among outliers. Evaluation of exceptional responders provides additional information that is often ignored in randomized controlled trials and before–after control‐intervention experiments. Interrogating the contextual factors that contribute to an exceptional outcome allow exceptional responders to become valuable pieces of information leading to unexpected discoveries and novel hypotheses.  相似文献   
564.
Impacts of flooding on the soil environment with regard to soil pollution with polycyclic aromatic hydrocarbons and s‐triazine (cyanazine, simazine, atriazine, propazine, prometryn) herbicides have been evaluated. No clear differences in the sum of the PAHs content were observed in the present studies. Only changes in the levels of individual PAHs were noted. In soils covered with flooding both at a depth of 0–20 and 20–40 high molecular weight PAHs were predominant (especially mutagenic and carcinogenic 5‐rings PAHs) whereas in non‐flooded areas, 2‐ and 3‐rings PAHs constituted over 80%. In the case of s‐triazine herbicides, no influence of flooding on the changes in their content in agriculturally used soils was noted. On the other hand, clearly lower levels of cyanazine, simazine and atriazine were not in the flooded forest soil as compared to the non‐flooded forest soil.  相似文献   
565.
Epilithic mosses are characterized by insulation from substratum N and hence meet their N demand only by deposited N. This study investigated tissue C, total Chl and δ13C of epilithic mosses along 2 transects across Guiyang urban (SW China), aiming at testing their responses to N deposition. Tissue C and total Chl decreased from the urban to rural, but δ13Cmoss became less negative. With measurements of atmospheric CO2 and δ13CO2, elevated N deposition was inferred as a primary factor for changes in moss C and isotopic signatures. Correlations between total Chl, tissue C and N signals indicated a nutritional effect on C fixation of epilithic mosses, but the response of δ13Cmoss to N deposition could not be clearly differentiated from effects of other factors. Collective evidences suggest that C signals of epilithic mosses are useful proxies for N deposition but further works on physiological mechanisms are still needed.  相似文献   
566.
This paper examines the historic development of the Brazilian sugarcane ethanol sector and the largely successful attempt to create a sustainable, renewable fuel for the transport sector. The policy that resulted from this process is an example of meeting the need for sustainable transport through the consideration of location‐specific characteristics and appropriate policy. The paper then questions the current and expected trajectory of the sugarcane ethanol sector with the focus on one key question: can sustainability be exported? In this analysis, the paper identifies new threats to the sustainability of Brazilian sugarcane ethanol and potential “opportunity costs” incurred in further development and internationalization of the sector. The paper concludes that exporting sugarcane ethanol may bring unanticipated deleterious consequences, which in turn means that both policy and theory need to be more precise about how sustainable transport is defined and bounded by time and space.  相似文献   
567.
Globally expanding human land use sets constantly increasing pressure for maintenance of biological diversity and functioning ecosystems. To fight the decline of biological diversity, conservation science has broken ground with methods such as the operational model of systematic conservation planning (SCP), which focuses on design and on‐the‐ground implementation of conservation areas. The most commonly used method in SCP is reserve selection that focuses on the spatial design of reserve networks and their expansion. We expanded these methods by introducing another form of spatial allocation of conservation effort relevant for land‐use zoning at the landscape scale that avoids negative ecological effects of human land use outside protected areas. We call our method inverse spatial conservation prioritization. It can be used to identify areas suitable for economic development while simultaneously limiting total ecological and environmental effects of that development at the landscape level by identifying areas with highest economic but lowest ecological value. Our method is not based on a priori targets, and as such it is applicable to cases where the effects of land use on, for example, individual species or ecosystem types are relatively small and would not lead to violation of regional or national conservation targets. We applied our method to land‐use allocation to peat mining. Our method identified a combination of profitable production areas that provides the needed area for peat production while retaining most of the landscape‐level ecological value of the ecosystem. The results of this inverse spatial conservation prioritization are being used in land‐use zoning in the province of Central Finland.  相似文献   
568.
Abstract

This study evaluated the role of water dispersible colloids with diverse physicochemical and mineralogical characteristics in facilitating the transport of metolachlor through macropores of intact soil columns. The soil columns represented upper solum horizons of an Alfisol in the Bluegrass region of Kentucky. Three different colloid suspensions tagged with metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐l‐methylethyl)acetamide] were introduced at a constant flux into undisturbed soil columns. The eluents were collected and analyzed periodically for colloid and metolachlor concentrations. Colloid recovery in the eluents ranged from 54 to 90 %. The presence of colloids enhanced the transport of metolachlor by 22 to 70 % depending on the colloid type and mobility. Colloids with higher pH, organic carbon, cation exchange capacity (CEC), total exchangeable bases (TEB), surface area (SA), and electrophoretic mobility (EM), showed better mobility, greater affinity for interaction with the herbicide and, thus, greater potential to co‐transport metolachlor. In contrast, increased level of kaolinite, Fe, and Al inhibited metolachlor adsorption and transport. In spite of the increased transportability of metolachlor by the presence of soil colloids, the colloid bound herbicide portion accounted for a very small part of the observed increase. This suggests that surface site exclusion mechanisms and preferential sorption induced by the presence of colloids are more important than ion exchange phenomena in promoting herbicide mobility in subsurface environments.  相似文献   
569.
Abstract: Understanding the risk of extinction of a single population is an important problem in both theoretical and applied ecology. Local extinction risk depends on several factors, including population size, demographic or environmental stochasticity, natural catastrophe, or the loss of genetic diversity. The probability of local extinction may also be higher in low‐quality sink habitats than in high‐quality source habitats. We tested this hypothesis by comparing local extinction rates of 15 species of Odonata (dragonflies and damselflies) between 1930–1975 and 1995–2003 in central Finland. Local extinction rates were higher in low‐quality than in high‐quality habitats. Nevertheless, for the three most common species there were no differences in extinction rates between low‐ and high‐quality habitats. Our results suggest that a good understanding of habitat quality is crucial for the conservation of species in heterogeneous landscapes.  相似文献   
570.
Abstract: Competitive species interactions may contribute to population declines. Purportedly, Red‐bellied Woodpeckers (Melanerpes carolinus), a common species, and Red‐cockaded Woodpeckers (Picoides borealis), an endangered species, compete for roosting and nesting cavities in living pine trees. To determine whether behavioral interactions measured at the individual level manifest themselves at the population level, we conducted field experiments designed to test whether the presence of Red‐bellied Woodpeckers resulted in a decrease in fitness to Red‐cockaded Woodpeckers. As part of a 4‐year study examining the nature of interspecific interactions in two populations of Red‐cockaded Woodpeckers (one stable, the Apalachicola Ranger District; one declining, the Wakulla Ranger District) in the Apalachicola National Forest, Florida, we conducted a set of Red‐bellied Woodpecker removal experiments. Paradoxically, following the removal of Red‐bellied Woodpeckers, we observed decreases in Red‐cockaded Woodpecker group size, proportion of nests that were successful, and proportion of individuals remaining on territories. Removal of Red‐bellied Woodpeckers may have exaggerated the immigration rate of Red‐bellied Woodpeckers to Red‐cockaded Woodpecker territories. The Red‐cockaded Woodpeckers in the Apalachicola Ranger District likely can withstand pressure from immigrating Red‐bellied Woodpeckers given that their population has remained relatively stable despite the presence of Red‐bellied Woodpeckers. A major factor of population persistence in the Wakulla Ranger District was the high turnover rate of adult female Red‐cockaded Woodpeckers, a phenomenon that was exacerbated by removal of Red‐bellied Woodpeckers. Relying solely on observations of apparently competitive interactions between individuals may not necessarily provide information about population‐level outcomes. Paradoxically, removing species that appear to be competitors may harm species of concern.  相似文献   
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