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81.
The fate and transport of antibiotics in natural water systems is controlled in part by interactions with nanometer (10−9 m) metal oxide particles. Experiments were performed by mixing solutions of ampicillin (AMP), a common, penicillin-class human and veterinary antibiotic, with 25 nm-TiO2 (anatase) nanoparticles at different pH conditions. Both sorption and degradation of AMP were observed in the AMP-nanoparticle solutions. For AMP concentrations from ∼3 μM to 2.9 mM the overall AMP removal from solution can be described by linear isotherms with removal coefficients (Kr) of 3028 (±267) L kg−1 at pH 2, 11,533 (±823) L kg−1 at pH 4, 12,712 (±672) L kg−1 at pH 6, and 1941 (±342) L kg−1 at pH 8. Mass spectral analysis of AMP solutions after removal of the solid nanoparticles yielded ions that indicate the presence of peniclloic acid, penilloic acid and related de-ammoniated by-products as possible compounds resulting from the degradation of AMP at the TiO2 surface. 相似文献
82.
Much of the literature on stress and organizational outcomes has focused on organizational factors and has ignored extraorganizational stressors that lead to perceived stress. However, research in other fields and recent studies in management suggests that acute‐extraorganizational stressors, such as traumatic events, may have potentially negative and costly implications for organizations. This study tests a theoretical model of traumatic stress and considers the relationship between strain from an acute‐extraorganizational stressor, the terrorist attack on September 11, 2001, and absenteeism. Using a sample of 108 MBA and MPA students, this study suggests that strain caused by an acute‐extraorganizational stressor can have important consequences for organizations. Namely, employees who report more strain from a traumatic life event are more likely to be absent from work in the weeks following the event. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
83.
The method of electrophoretic separation of nuclear eye-lens proteins was applied to a study of the population structure of the striped mullet Mugil cephalus L. in Hawaii. Electropherograms produced 5 pattern types, with most variations due to non-developmental genetic polymorphism. Some variations, however, were associated with size, and an ontogenetic basis was considered. The frequencies of the pattern types were significantly (p<0.005) independent among the three geographical subpopulations examined: Kaneohe Bay, Oahu; Diamond Head, Oahu; and Kawaihae Bay, Hawaii. Growth rates of mullet eye-lens nuclei demonstrated significant (p<0.05) differences between sexes and localities, except for Kaneohe Bay males versus Diamond Head males, which were nearly significant (p 0.075). These variations in eye-lens nuclei growth rates are probably regulated by genetic factors. Nearly complete genetic isolation is evident for the three subpopulations of mullet in the Hawaiian Islands. The occurrence of genetic interchange in apparently less frequent between the Oahu and Hawaii populations than between the two Oahu populations, in accordance with their respective geographical distances.Oceanic Institute Contribution No. 72. 相似文献
84.
Marcellus M. Caldas Jason S. Bergtold Jeffrey M. Peterson Dietrich H. Earnhart 《Journal of Land Use Science》2016,11(5):579-594
Among the important alternatives for land conservation is the US Conservation Reserve Program (CRP) that celebrated its 30th anniversary in 2015. This paper explores how landowners decide on alternative land-use choices made available by the expiration of CRP contracts in Kansas. The study uses survey data and multinomial Logit models to predict land-use choices. Two models were tested. The first model does not incorporate variables concerning farmer perceptions and attitudes about land-use choices, while the second model does. The results show that CRP re-enrollment depends on factors, such as years of experience in cropping and percent of cropland irrigated. However, when perception variables are added, the models become more robust in explaining other land choice alternatives. The results suggest that as the perception of unfairness of more inflexible environmental policy rises, these farmers may be more likely to re-enroll their marginal land in the CRP program. 相似文献
85.
Mark J. Peterson George R. Southworth W. Dennis Crumby 《Environmental monitoring and assessment》1996,40(1):91-105
Sunfish and a minnow species were used as indicators of anthropogenic mercury contamination in an east Tennessee stream system receiving multiple point and non-point discharges. The monitoring of bluegill (Lepomis macrochirus) and redbreast sunfish (Lepomis auritus) identified bioavailable mercury near three geographically separate industrial facilities, and was able to detect decreases in contamination with distance away from these facilities. In general, total mercury concentrations in the tissue of sunfish in this study were low in comparison to the most commonly cited human health threshold limits, although concentrations at some sites exceeded 1 g/g. Caged blacknose dace (Rhinichthys atratulus) were monitored in conjunction with resident fish as an indicator of more discrete sources in selected headwater streams where fish movement was deemed a potential factor affecting mercury body burdens. Mercury concentrations in muscle tissue of caged dace after 12 weeks exposure were generally low (<0.2 g/g) at all sites but higher than in fish from reference streams. mercury accumulation varied between species (sunfish vs. dace) and monitoring method (caged vs. resident) at the same site, with sunfish tending to accumulate higher concentrations of mercury than resident dace which, in turn, contained about twofold higher concentrations than caged dace. However, the site-to-site pattern of mercury accumulation was similar. This study demonstrates the utility of using small stream dwelling fish with restricted home ranges as a tool for identifying and evaluating the bioavailability of mercury sources in large industrial or urbanized settings. 相似文献
86.
Stefaniak AB Hoover MD Day GA Dickerson RM Peterson EJ Kent MS Schuler CR Breysse PN Scripsick RC 《Journal of environmental monitoring : JEM》2004,6(6):523-532
Little is known about the physicochemical properties of beryllium aerosols associated with increased risk of beryllium sensitization and chronic beryllium disease (CBD). Such information is needed to evaluate whether airborne mass of beryllium is the appropriate metric of exposure or alternatively to provide a scientific basis for using information on particle size, surface area, and chemistry to support an improved exposure limit based on bioavailability through the inhalation and dermal routes of exposure. Thus, we used a suite of analytical techniques to characterize aerodynamically size-fractionated beryllium particles and powders that have been associated in epidemiological studies with higher prevalence of CBD. Aerosol particles were sampled from the ventilation systems of production lines for powders of beryllium metal and beryllium oxide and for ingots of copper-beryllium alloy. End product powders from the metal and oxide production lines were also collected.Particles released during production of beryllium metal were found to be complex, having heterogeneous composition, including reactive species such as fluorine. Powders from beryllium metal production were of high purity with only a minor component of beryllium oxide. Both particles and powders from oxide production were high-purity oxide. Particles released during production of copper-beryllium alloy were heterogeneous, being predominantly copper oxides. Thus, all particles and powders contain at least some beryllium in the form of beryllium oxide.These data justify efforts to thoroughly characterize beryllium aerosol properties when performing exposure assessments. The data also suggest that differences in particle chemical composition, size, number, and surface area may influence bioavailability of beryllium and contribute to risk of CBD. However, a scientific basis does not yet exist to replace mass as the current metric of exposure. 相似文献
87.
Sonja Peterson 《Environmental Modeling and Assessment》2006,11(1):1-17
The analysis of climate change is confronted with large uncertainties that need to be taken into account to arrive at meaningful
policy recommendations. The main contribution of economics to this interdisciplinary task is to provide formal frameworks
and techniques for analyzing climate policy in the context of uncertainty. This paper will give an overview of existing approaches
and findings to provide a broad picture of what economics can contribute to the debate. 相似文献
88.
Guidelines for the early stages of developing a monitoring program are presented. Jumping right into a monitoring program based on standard protocols and a number of commonly monitored parameters is an attractive idea, but it is unlikely to lead to an intelligent allocation of time and money. Rather, a number of well-defined planning steps must be followed before monitoring is begun:
- Objectives for the program should be well defined.
- The attributes to be monitored in order to meet objectives should be listed.
- Methods of monitoring these attributes should be developed.
- A pilot study should be conducted to determine spatial and temporal variability of the attributes being monitored and the cost of sampling.
- The results of the pilot study should be carefully evaluated to determine whether program objectives can be met for an acceptable cost.
- Objectives, attributes to be monitored, and methods should be revised in accordance with the results of the pilot study.
89.
Cristi Horton Damon Hall Susan Gilbertz Tarla Peterson 《Environmental Communication: A Journal of Nature and Culture》2017,11(5):609-623
We explored the communicative construction of a conservationist identity among primary producers by excavating voices of agriculturalists operating along the Yellowstone River (Montana, USA). We used a cultural inventory approach to discover and then listen to informants’ voices as they constructed their conservation identity. Those who self-identified as conservationists talked about their ecological and social responsibilities, and described challenges they faced in protecting individual resources and system processes of the watershed. For these agriculturalists, conservation and production are inextricably linked, and enable them to provide a sustainable resource base for future generations. Insight from these voices enhances understanding of what sustainability could mean to those who self-identify as both conservationists and primary producers. 相似文献
90.
Richard B. Peterson 《Local Environment》2005,11(1):109-125
This paper is based on the author's fieldwork on the incorporation of local cultural understandings in the design of rural sustainability projects in the Democratic Republic of Congo. It explores several narratives about Mami Wata, mythological aquatic figures widely known in West and Central Africa, and their meanings for small-scale waterpower development projects, or micro-hydros. Careful examination of such narratives represents one way in which local conceptions and understandings can inform rural development policy, especially with regard to the social distribution of the benefits such projects aim to bring. When designing policies, development agents and agencies would do well to take these mythological and spiritual dimensions of local people's reality seriously rather than dismiss them as irrelevant, or simply as non-empirical phenomena and therefore without effects. The paper concludes with some concrete suggestions for policy action, paying special attention to how researchers and policymakers can work together to integrate local understandings more effectively into rural development strategies. 相似文献