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271.
272.
An individual's perception of risk develops from his or her values, beliefs, and experiences. Social scientists have identified factors that affect perceptions of risk, such as whether the risk is knowable (uncertainty), voluntary (can the individual control exposure?), and equitable (how fairly is the risk distributed?). There are measurable differences in how technical experts and citizen stakeholders define and assess risk. Citizen knowledge and technical expertise are both relevant to assessing risk; thus, the 2002 National Research Council panel on biosolids recommended stakeholder involvement in biosolids risk assessments. A survey in 2002 identified some of the factors that influence an individual's perception of the risks involved in a neighbor's use of biosolids. Risk communication was developed to address the gap between experts and the public in knowledge of technical topics. Biosolids management and research may benefit from applications of current risk communication theory that emphasizes (i) two-way communications (dialogue); (ii) that the public has useful knowledge and concerns that need to be acknowledged; and (iii) that what may matter most is the credibility of the purveyor of information and the levels of trustworthiness, fairness, and respect that he or she (or the organization) demonstrates, which can require cultural change. Initial experiences in applying the dialogue and cultural change stages of risk communication theory--as well as consensus-building and joint fact-finding--to biosolids research suggest that future research outcomes can be made more useful to decision-makers and more credible to the broader public. Sharing control of the research process with diverse stakeholders can make research more focused, relevant, and widely understood.  相似文献   
273.
/ As federal land management agencies such as the USDA Forest Service increasingly choose to implement collaborative methods of public participation, research is needed to evaluate the strengths and weaknesses of the technique, to identify barriers to effective implementation of collaborative processes, and to provide recommendations for increasing its effectiveness. This paper reports on the findings of two studies focused on the experiences of Forest Service employees and their external partners as they work to implement collaborative planning processes in national forest management. The studies show both similarities and differences between agency employees and their partners in terms of how they evaluate their collaborative experiences. The studies reveal that both Forest Service employees and external partners are supportive of collaborative planning and expect it to continue in the future, both see the trust and relationships built during the process as being its greatest benefit, and both see the Forest Service's organizational culture as the biggest barrier to effective collaborative efforts. The groups differed in terms of evaluating each other's motivation for participating in the process and in whether the process was a good use of time and resources, with external partners seeing it as too drawn out and expensive. The paper concludes with a discussion of the policy implications and changes necessary to increase the effectiveness of collaborative efforts within the Forest Service and other federal land management agencies.KEY WORDS: Public land management; Collaborative planning; National forests; Public participation  相似文献   
274.
In western Alaska, mercury (Hg) could be a potential health risk to people whose diet is primarily fish-based. In 2000, total Hg (THg) and methylmercury (MeHg) were examined in northern pike (Esox lucius) and Arctic grayling (Thymallus arcticus) from two watersheds in western Alaska, the Yukon and Kuskokwim rivers. Whitefish (Coregonus sp.) were also examined from the Kuskokwim River. Pike from the Yukon and Kuskokwim rivers had mean concentrations of THg in muscle of 1.506 and 0.628 mg/kg wet wt, respectively. The mean concentrations of THg in grayling muscle from these rivers were 0.264 and 0.078 mg/kg, respectfully. Whitefish had a mean THg concentration in muscle of 0.032 mg/kg. MeHg, in pike and grayling constituted nearly 100% of the THg concentrations; the proportion was less in whitefish. A significant positive correlation between Hg levels and fish length was also found. Generally, there were no changes in Hg concentrations in pike or grayling over the last several years. Only pike from theYukon River had THg concentrations that exceeded the USFDA action level for human consumption of edible fish (1 mg/kg). Human hazard index for pike was > or = 1 for both adults and children, indicating a potential for toxic concern, especially among children. Further studies are needed to determine the environmental and human health impacts associated with these Hg concentrations in western Alaska, especially in the context of potentially increased consumption of resident fishes when anadromous salmon catches are reduced.  相似文献   
275.
Summary Male milkweed beetles (Tetraopes tetraophthalmus) are shown to exhibit choice between potential mates. Males, however, also exhibit direct competition for access to potential mates. These differences in male behavior are dependent on the local sex ratio, with males becoming increasingly choosy when the sex ratio is female-biased, and more competitive when the sex ratio is malebiased. Females show neither choice nor competition. In both the laboratory and in the field, body size is important in determining patterns of competition and choice. Larger males win most aggressive encounters, and males generally prefer large females as mates. The combination in a single sex, of competition for mates and mate choice is not predicted by classical sexual selection theory. Male choice and competition may have evolved in T. tetraophthalmus due to the combination of (1) the mating system (2) the pattern of variation in female fecundity, and (3) the spatially and temporally variable operational sex ratios. This explanation is not dependent on high heritability of body size.  相似文献   
276.
277.
Understanding the nutritional requirements of Lytechinus variegatus is essential to define its role in the marine environment and necessary for successful culture of this species. Protein is an essential component for growth, yet the requirements for protein in most marine organisms are not known. Small Lytechinus variegatus (ca. 14 mm diameter, n=160) were collected at St. Joseph Bay, Florida in March 2000. They were held in aquaria and fed ad libitum one of four diets varying in protein concentration (9, 15, 21, or 33% dry weight) for 14 weeks. Diets 21% dry weight protein were sufficient for maximal growth and survivorship. Individuals fed a diet low in protein compensated by consuming higher quantities of food per gram wet weight. However, the protein was insufficient to support maximal growth and survivorship. Total dry matter absorption, protein absorption, and carbohydrate absorption of the prepared feeds were higher than reported for natural diets. Total production and production efficiency was lowest in those fed the low-protein diet. Gonad production occurred in individuals with test diameters smaller than reported previously in field populations and was lowest in those fed the low-protein diet. The acini of both females and males were predominantly composed of nutritive phagocytes, suggesting that growing L. variegatus use the gonad primarily as a nutrient storage organ and not for reproduction. In females the growth rate of oocytes increased with dietary protein. In males, protein concentration 21% resulted in an increase in the volume of germinal epithelium and a decrease in the volume of nutritive phagocytes. The minimal requirement for protein in L. variegatus from approximately 1 g to 15 g total weight is >15% dry weight for the conditions of this experiment. The requirement for a diet >15% protein corroborates with field studies that indicate L. variegatus consumes epibionts and animal tissues preferentially to seagrass, and that the microbial, microfloral, and microfaunal community living on the seagrass may provide the extra protein required for growth and survival of small L. variegatus.Communicated by P.W. Sammarco, Chauvin  相似文献   
278.
AdultLuidia clathrata (Say) were held at salinities lower and higher (25 to 35) than environmental salinity (29) during gametogenesis and after sperm and primary oocytes were produced. The sperm and primary oocytes acclimated to the experimental salinities in both cases. Fertilization and development through gastrulation were not affected at the salinities at which the parents were held, but were affected at altered salinities. This indicates that intracellular osmoregulation can occur both during gametogenesis and after the stage of arrested activity has been reached. This is an important capacity forL. clathrata, which lives in estuaries with variable salinities.  相似文献   
279.
Gaseous volatiles from wastewater samples taken from a local sewage treatment plant were air-stripped and trapped onto Tenax GC. These volatiles were then thermally desorbed and subsequently analyzed using a gas chromatograph coupled to a mass spectrometer (GC-MS). The results show that saturated aliphatic and aromatic hydrocarbons were the most dominant compounds found in the sewage gaseous volatiles. Other compounds found were chlorinated hydrocarbons, organic acids, sulfides and phenols. A wide variety of gaseous volatiles were found in the raw wastewater, the primary clarifier effluent, the pre-aeration wastewater and the sludge samples. A comparison of the gas chromatograms for the pre- and post-aeration wastewater shows that many odorous gaseous volatiles were removed during the aeration process in the treatment plant.  相似文献   
280.
Traditional approaches to the siting of potentially hazardous but regionally necessary facilities are often ineffective and lead to drawn-out legal disputes ultimately satisfactory to none of the parties. Research at MIT over the last decade has indicated five factors that may solve the siting puzzle. Application of these principles do not guarantee that a decision will not be disputed but may enhance the possibility of a wise and durable agreement.  相似文献   
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