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241.
We combined a natural experiment with field surveys and GIS to investigate the effects of dust from recreational trails and
access roads on the federally threatened Valley elderberry longhorn beetle (“VELB,” Desmocerus californicus dimorphus) and its host plant, elderberry (Sambucus mexicana). Dust is listed in the species recovery plan as a threat to the VELB and unpaved surfaces are common throughout the riparian
corridors where the VELB lives, yet the effects of dust on the VELB have been untested. We found that dust deposition varied
among sites and was highest within 10 m of trails and roads, but was similar adjacent to dirt and paved surfaces within sites.
Elderberry density did not differ with distance from dirt surfaces. Despite similar within-site dust levels, elderberry adjacent
to paved surfaces were less stressed than those near dirt ones, possibly because increased runoff from paved surfaces benefited
elderberry. Dust deposition across sites was weakly correlated with elderberry stress symptoms (e.g., water stress, dead stems,
smaller leaves), indicating that ambient dust (or unmeasured correlates) influenced elderberry. Direct studies of the VELB
showed that its distribution was not negatively affected by the proximity to dirt surfaces. Dust from low traffic dirt and
paved access roads and trails, therefore, affected VELB presence neither directly nor indirectly through changed elderberry
condition. These results suggest that the placement of VELB mitigation, restoration, and conservation areas can proceed independently
of access roads if dust and traffic levels do not exceed those in our study site. Furthermore, dust control measures are likely
to be unnecessary under such conditions. The potential effects of increased traffic and dust levels are addressed through
a literature review. 相似文献
242.
Urbanization,land use,and water quality in Shanghai. 1947-1996 总被引:24,自引:0,他引:24
Ren W Zhong Y Meligrana J Anderson B Watt WE Chen J Leung HL 《Environment international》2003,29(5):649-659
The paper undertakes a preliminary investigation into the relationship between water quality and urbanization as well as the changing patterns of land use within Shanghai. Longitudinal changes to water quality at various points along the course of the Huangpu River are analysed and compared to changes in the rates of urbanization and changes in land uses. The results reveal that rapid urbanization corresponds with rapid degradation of water quality. It also shows that urban land uses are positively correlated with the decline in water quality. A regression model shows that close to 94% of the variability in water quality classifications is explained by industrial land area. The paper concludes with the need for comprehensive land use planning as a way of protecting valuable water resources. 相似文献
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The present study aimed to determine the extent to which variation in the uptake of serum screening for Down syndrome reflects variation in the way the test is offered. A higher uptake of serum screening was seen at hospitals that offered the blood test as part of a routine visit than at those where screening required a separate visit. The type of screening test offered and whether a reminder was sent were not associated with uptake. Given the consensus that undergoing screening should be the result of an informed choice, further research is needed to determine which methods of offering serum screening facilitate and which impede informed choice. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
246.
Respiratory Suspended Particulate (RSP) Concentration and its Implications to Roadside Workers: A Case Study of Hong Kong 总被引:1,自引:0,他引:1
The adsorption behaviour of Diphenylamine (DPAM), napthylamine ( NAM), napthylamine ( NAM)and aniline on pyrolusite and activated carbon has been studied.Pyrolusite shows remarkable sorption capacity for DPAM and NAM as compared to aniline; (the adsorption followed theorder:Activated Carbon: DPAM = NAM > AnilinePyrolusite: DPAM: NAM > NAM> Aniline)The maximum adsorption of NAM occurred in theconcentration range 4–20 g mL-1 on pyrolusite (95%)and 4–50 g mL-1 on activated carbon (100%). Theeffect of various doses of activated carbon on the adsorption of NAM confirm Langmuir and Freundlich isotherms where asFreundlich isotherm is obeyed by pyrolusite. The adsorption of NAM on both the absorbents is not affected in presence ofDPAM over a wide range of their initial concentrations (20–60g mL-1). The desorption studies of NAM onpyrolusite was carried out by batch as well as column processes.Excellent results were obtained when a mixture of n-hexane andisopropanol (91:1) was used as eluent. 相似文献
247.
Mark A. Chappell Donald N. Janes Vaughan H. Shoemaker Theresa L. Bucher Shane K. Maloney 《Behavioral ecology and sociobiology》1993,33(3):173-182
Summary We estimated reproductive effort (energy expenditures for reproduction, as opposed to maintenance) in Adélie penguins breeding at Palmer Station, Antarctica. Data on body composition changes and metabolic rate were obtained using isotopic methods. Adelie breeding behavior consists of an initial courtship stage (during which both sexes fast), incubation, the guard stage (when chicks are 1 to 18–28 days old), and the creche stage (from the end of guarding until chicks are 28–45 days old). Both males and females lost considerable mass during the initial stages of the reproductive season, but males fasted longer and lost more mass. Mass losses of both sexes consisted of 66% depot fat and 34% lean tissue. Mass and body composition remained constant once birds resumed feeding. The metabolic expenditure for the foraging necessary to accumulate the mass lost while fasting — one component of reproductive effort —was about 63 MJ in males and 39 MJ in females. Field metabolic rates (FMR) were low during courtship and while incubating, increasing more than 2-fold when birds resumed foraging. Although mean FMR increased between incubation and the creche stage, differences between stages were small and not significant. We used FMR data and an energy balance model to estimate the cost of feeding chicks. Results suggest a maintenance FMR of about 2.7 × basal metabolism (BMR), increasing to 3.4–3.6 × BMR during the creche stage. The reproductive effort (as metabolic expenditures) associated with feeding chicks is 31 MJ (males) to 36 MJ (females). Cumulative reproductive effort is 94 MJ in males and 75 MJ in females, or 5.3–6.2% of the annual energy budget. The reproductive effort devoted to chick care does not appear to be constrained by physiological or time limitations. Instead, selection to reduce the risk of predation may prevent the evolution of increased parental care.
Correspondence to: M.A. Chappell 相似文献
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