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891.
892.
Despite biological invasions being a worldwide phenomenon causing significant ecological, economic, and human welfare impacts, there is limited understanding regarding how environmental managers perceive the problem and subsequently manage alien species. Spanish environmental managers were surveyed using questionnaires to (1) analyze the extent to which they perceive plant invasions as a problem; (2) identify the status, occurrence, and impacts of noxious alien plant species; (3) assess current effort and expenditure targeting alien plant management; and, finally, (4) identify the criteria they use to set priorities for management. In comparison to other environmental concerns, plant invasions are perceived as only moderately problematic and mechanical control is the most valued and frequently used strategy to cope with plant invasions in Spain. Based on 70 questionnaires received, 193 species are considered noxious, 109 of which have been the subject of management activities. More than 90% of species are found in at least one protected area. According to respondents, the most frequently managed species are the most widespread across administrative regions and the ones perceived as causing the highest impacts. The perception of impact seems to be independent of their invasion status, since only half of the species identified as noxious are believed to be invasive in Spain, while 43% of species thought to only be casual aliens are causing a high impact. Records of management costs are poor and the few data indicate that the total actual expenditure amounted to 50,492,437 € in the last decade. The majority of respondents stated that management measures are insufficient to control alien plants due to limited economic resources, lack of public awareness and support, and an absence of coordination among different public administrations. Managers also expressed their concern about the fact that much scientific research is concerned with the ecology of alien plants rather than with specific cost-efficient strategies to manage alien species.  相似文献   
893.
Following the intent of the National Environmental Policy Act of 1969, many states have adopted policies and procedures directing state agencies and local government units to evaluate the potential environmental impacts of development projects prior to their undertaking. In contrast to a rich literature on federal requirements, current understanding of state environmental review is narrowly focused and outdated. This paper seeks to provide information on the landscape of state environmental review policy frameworks. The paper identifies 37 states with formal environmental review requirements through a document review of state statutes, administrative rules and agency-prepared materials, and confirms this finding through a survey of state administrators. A two-tier classification is used to distinguish states based on the approach taken to address environmental review needs and the scope and depth of relevant policies and procedures implemented. This paper also provides a discussion of policy and programme attributes that may contribute to effective practice, and of the potential for adopting relevant legislation in states where environmental review is currently lacking.  相似文献   
894.
This paper explores the attitudes of landowners across Ireland to the wider provision of public access for recreational walking using a multinomial logit model. The study also investigates the level of compensation required to improve the supply of this public good. Results indicate that 51% of landowners are not willing to provide access (non-providers), 21% are willing to provide access free of charge (free providers) and 28% seek compensation (willing providers). The findings indicate that participation by landowners in a proposed public access scheme is influenced by landowners' experience with walkers, farm type, farm insurance costs, household demographics, regional variations, opportunity cost of land and participation in other agri-environment schemes. Mean willingness-to-accept for landowners willing to facilitate improved public access for walking was found to be €0.27 per metre of walkway.  相似文献   
895.
The relationship between primary and scrap prices has been hypothesized for the most part as unidirectional, characterized by spillovers from primary to scrap prices. The purpose of this study is to evaluate empirically the dynamic interactions between primary and scrap metal prices through multivariate time series methods. In addition, the study expands the investigation at the level of volatility transmission, which has not been previously examined. The metal prices utilized are for copper, lead, and zinc for the period 1984–2001. The paper demonstrates differing long run and short run links. Scrap prices do not improve the long run interpretation of primary prices, but information flows from the scrap to the primary markets exist in the short run. Additionally, the copper and lead markets exhibit bidirectional information flows in terms of volatility transmission. The analysis provides valuable insight into the interactions of the primary and scrap metal sectors which can be used to improve forecasting and planning.  相似文献   
896.
A compilation has been undertaken of data which can be used to derive animal product transfer coefficients for radionuclides, including an extensive review of Russian language information. The resultant database has been used to provide recommended transfer coefficient values for a range of radionuclides to (i) cow, sheep and goat milk, (ii) meat (muscle) of cattle, sheep, goats, pigs and poultry and (iii) eggs. The values are used in a new IAEA handbook on transfer parameters which replaces that referred to as ‘TRS 364’. The paper outlines the approaches and procedures used to identify and collate data, and assumptions used. There are notable differences between the TRS 364 ‘expected’ values and the recommended values in the revised Handbook from the new database. Of the recommended values, three milk values are at least an order of magnitude higher than the TRS 364 values (Cr, Pu (cow) Pu (sheep)) and one milk value is lower (Ni (cow)). For meat, four values (Am, Cd, Sb (beef) I (pork)) are at least an order of magnitude higher than the TRS 364 values and eight values are at least an order of magnitude lower (Ru, Pu (beef), Ru, Sr, Zn (sheep), Ru, Sr (pork), Mn (poultry)). Many data gaps remain.  相似文献   
897.
Radioxenon isotopes play a major role in confirming whether or not an underground explosion was nuclear in nature. It is then of key importance to understand the sources of environmental radioxenon to be able to distinguish them from those of a nuclear explosion.  相似文献   
898.
899.
Samples of precipitation events (snow and rain) in Dalian, a typical coastal town in China, were analyzed for perfluorosulfonates (PFSAs) and perfluorocarboxylates (PFCAs) to investigate atmospheric contamination by these compounds. In the snow event on December 16, 2006, samples were collected from 21 different sites and in another 6 precipitation events, samples were collected from a single location. Four PFSAs (C4, C6, C8, C10) and seven PFCAs (C6–12) were analyzed. Among the homologues, perfluorooctane sulfonate (PFOS) concentrations were the highest with a geometric mean (GM) of 145 ng/L (n = 21) during the snow event on December 16, 2006, followed by perfluorooctanoate (PFOA) with a GM of 24.7 ng/L (n = 21). Concentrations of perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS) and perfluoroheptanoate (PFHpA) were more than two orders of magnitude lower than that of PFOS. Other PFSAs and PFCAs were found to be below the limit of detection in all the samples. In other 6 precipitation events, PFSAs and PFCAs were detected approximately in the same order of magnitude in both snow and rain. The results indicate that wet deposition may be a potential transport mechanism of perfluorinated chemicals in the environment.  相似文献   
900.
The Mining and Chemical Industrial Combine, Zheleznogorsk (MCIC, previously known as Krasnoyarsk-26) on the River Yenisey has contaminated the surrounding environment with anthropogenic radionuclides as a result of discharges of radioactive wastes. The purpose of this study was to investigate the vertical distribution of anthropogenic contamination (137Cs and plutonium) within floodplain areas at different distances from the discharge point. Sites were chosen that display different characteristics with respect to periodic inundation with river water. Cs-137 activity concentrations were in the range 23–3770 Bq/kg (dry weight, d.w.); Pu-239,240 activity concentrations were in the range <0.01–14.2 Bq/kg (d.w.). Numerous sample cores exhibited sub-surface maxima which may be related to the historical discharges from the MCIC. Possible evidence indicating the deposition of earlier discharges at MCIC in deeper core layers was observed in the 238Pu:239,240Pu activity ratio data: a Pu signal discernible from global fallout could be observed in numerous samples. Cs-137 and Pu-239,240 activity concentrations were correlated with the silt fraction (% by mass <63 μm) though no significant correlation was observed between (grain-size) normalised 137Cs activity concentrations and distance downstream from the MCIC.  相似文献   
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