Islands in time: Island sociogeography and Mediterranean prehistory     

Alan H. Simmons 《Geoarchaeology》1997,12(7):806-809

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Exploring the Association of Communication Satisfaction with the Oil and Natural Gas Industry and Risk Perceptions of Shale Energy Development     

Gene L. Theodori  Richard S. Bello 《社会与自然资源》2019,32(7):841-847

Despite the vast literature on shale energy development, surprisingly little empirical research has been conducted on the shale energy communicators, communication practices, and community outreach programs. Using data drawn from a random sample of individuals in two counties in the Eagle Ford Shale region of south Texas, we present a newly-constructed unidimensional scale that can be used to measure stakeholders’ level of satisfaction with the oil and natural gas industry’s communication performance. We then examine the relationship between individuals’ level of communication satisfaction with the oil and gas industry and their perceptions of risk in regard to shale energy development in the Eagle Ford Shale. We find substantial support for the hypothesis that communication satisfaction with the oil and natural gas industry is negatively associated with risk perception. We conclude the paper with several suggestions for future research.  相似文献   

Analysis of nonlinear associations between prenatal methylmercury exposure from fish consumption and neurodevelopmental outcomes in the Seychelles Main Cohort at 17 years     

Li-Shan?HuangEmail authorView author&#;s OrcID profile  Deborah?A.?Cory-Slechta  Christopher?Cox  Sally?W.?Thurston  Conrad?F.?Shamlaye  Gene?E.?Watson  Edwin?van Wijngaarden  Grazyna?Zareba  J.?J.?Strain  Gary?J.?Myers  Philip?W.?Davidson 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(4):893-904

The Seychelles Child Development Study has been examining the relationship between prenatal methylmercury (MeHg) exposure from consuming fish during pregnancy and child development. This study re-analyzes seven outcomes in the 17 year Main Cohort data to determine if there are nonlinear or non-homogeneous (subgroup) associations that were not identified in the linear analysis. We adopted two statistical approaches. First, we carried out an additive nonlinear analysis assuming homogeneous prenatal MeHg-outcome relationships to explore overall associations. Second, we applied the regression tree to the Woodcock–Johnson Calculation subtest (it was significantly associated in earlier analyses) and identified 4 clusters based on covariates. Then we used additive models to assess the prenatal MeHg association in each of the four clusters for all seven outcomes. This approach assumes nonlinear associations in each cluster and non-homogeneous associations between clusters. The additive nonlinear analysis yielded prenatal MeHg curves similar to the linear analysis. For the regression tree analysis, the curves relating prenatal MeHg to outcomes between the 4 clusters differed and some crossed at higher prenatal MeHg levels, suggesting non-homogeneity in the upper range of exposure. Additionally, some of the curves suggested a possible non-linear relationship within the range of exposure we studied. This non-linear analysis supports the findings from the linear analysis. It shows little evidence to support an adverse association of prenatal MeHg exposure through maternal consumption of fish contaminated with natural background levels. However, the tree analysis suggests that the prenatal exposure/outcome relationship may not be homogeneous across all individuals and that some subpopulations may have an adverse association in the upper range of the exposures studied. More robust data in the higher levels of exposure in this cohort are needed to confirm this finding.  相似文献   

Effects of Intraborehole Flow on Purging and Sampling Long-Screened or Open Wells     

David L. Poulsen  Peter G. Cook  Craig T. Simmons  James L. McCallum  Shawan Dogramaci 《Ground water》2019,57(2):269-278

Hydraulic head differences across the screened or open interval of a well significantly influence the sampled water mixture. Sample bias can occur due to an insufficient pumping rate and/or due to native groundwater displacement by intraborehole flow (IBF). Proper understanding of the sampled water mixture is crucial for accurate interpretation of environmental tracers and groundwater chemistry data, and hence groundwater characterization. This paper uses numerical modeling to quantify sample bias caused by IBF in an un-pumped high-yield well, and the influence of pumping rate and heterogeneity on the volume of pumpage required to purge an IBF plume. The results show that (1) the pumping rate must be at least an order of magnitude greater than the IBF rate to achieve permeability-weighted yield, (2) purge volume was 2.2 to 20.6 times larger than the IBF plume volume, with the ratio depending on plume location relative to hydraulic conductivity and head distributions, and (3) after an example 1000-day un-pumped period, purging required removal of at least three orders of magnitude more water than the common practice of three to five well volumes. These results highlight the importance of knowing the borehole flow regime to identify IBF inflow and outflow zones, estimate IBF rates, and to develop a strategic sampling approach.  相似文献   

Predicting Water Resource Impacts of Unconventional Gas Using Simple Analytical Equations          下载免费PDF全文

P.G. Cook  A. Miller  M. Shanafield  C.T. Simmons 《Ground water》2017,55(3):387-398

The rapid expansion in unconventional gas development over the past two decades has led to concerns over the potential impacts on groundwater resources. Although numerical models are invaluable for assessing likelihood of impacts at particular sites, simpler analytical models are also useful because they help develop hydrological understanding. Analytical approaches are also valuable for preliminary assessments and to determine where more complex models are warranted. In this article, we present simple analytical solutions that can be used to predict: (1) the spatial extent of drawdown from horizontal wells drilled into the gas‐bearing formation, and rate of recovery after gas production ceases; (2) the potential for upward transport of contaminants from the gas‐bearing formation to shallow aquifers during hydraulic fracturing operations when pressures in the gas‐bearing formation are greatly increased; and (3) the potential downward leakage of water from shallow aquifers during depressurization of gas‐bearing formations. In particular, we show that the recovery of pressure after production ceases from gas‐bearing shale formations may take several hundred years, and we present critical hydraulic conductivity values for intervening aquitards, below which the impact on shallow aquifers will be negligible. The simplifying assumptions inherent in these solutions will limit their predictive accuracy for site‐specific assessments, compared to numerical models that incorporate knowledge of spatial variations in formation properties and which may include processes not considered in the simpler solutions.  相似文献   

The Elder Problem          下载免费PDF全文

Craig T. Simmons  John W. Elder 《Ground water》2017,55(6):926-930

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深圳湾海域多溴联苯醚(PBDEs)生物累积及其高分辨沉积记录   总被引：5，自引：0，他引：5  

丘耀文  张干  郭玲利  Gene J Zheng  李军  刘向 《海洋与湖沼》2009,40(3):261-268

深圳湾,毗邻香港,是深圳经济特区的重要经济发展和生态调节区域。为了更好地了解该湾多溴联苯醚（PBDEs）的生物累积规律及其污染历史,作者采集该海域19个鱼、2个虾、2个蟹和柱状沉积物样品,分析其中PBDE的组分与含量,以及生物体的δ^15N同位素、总脂含量和柱状沉积物的沉积年龄（^210pb）、总有机碳（TOC）。结果表明,深圳湾海域鱼类∑15 PBDEs组分的残余量为21—167ng／g lw（或0．17—4．16ng／g fw）,平均为（67±42）ng／g lw或（2．00±1．14）ng／g fw,其含量与生物体的δ^15N同位素和脂含量正相关,BDE-47、BDE-100为生物体中PBDE最优势组分且在所有生物样品中均检出,分别占46．5％、13．5％,肉食性的鱼类较植食性的鱼类PBDEs的生物累积总体上较高。柱状沉积物中∑22 PBDEs含量（0．07—4．85ng／g dw）近二十几年来有明显的上升趋势,平均沉积通量为0．25ng／（cm^2·a）,丰度最高的PBDE组分为BDE-47、BDE-49、BDE-99、BDE-183（不包括BDE-209）;PBDEs在生物体和柱状沉积物中的含量位于全球PBDEs含量的中低端范围;鱼类等生物体中PBDE的生物-沉积物累积比值（BSAF）比值（〈0．8）较小,与相应的PBDE的log Kow（辛醇／水分配比）存在一定的正相关性。  相似文献   

Depth-stratified phytoplankton dynamics in Cyclone Opal, a subtropical mesoscale eddy     

Michael R. Landry  Susan L. Brown  Yoshimi M. Rii  Karen E. Selph  Robert R. Bidigare  Eun Jin Yang  Melinda P. Simmons 《Deep Sea Research Part II: Topical Studies in Oceanography》2008,55(10-13):1348

As part of E-Flux III cruise studies in March 2005, we investigated phytoplankton community dynamics in a cyclonic cold-core eddy (Cyclone Opal) in the lee of the Hawaiian Islands. Experimental incubations were conducted under in situ temperature and light conditions on a drift array using a two-treatment dilution technique. Taxon-specific estimates of growth, grazing and production rates were obtained from analyses of incubation results based on phytoplankton pigments, flow cytometry and microscopy. Cyclone Opal was sampled at a biologically and physically mature state, with an 80–100 m doming of isopycnal surfaces in its central region and a deep biomass maximum of large diatoms. Depth-profile experimentation defined three main zones. The upper (mixed) zone (0–40 m), showed little compositional or biomass response to eddy nutrient enrichment, but growth, grazing and production rates were significantly enhanced in this layer relative to the ambient community outside of the eddy. Prochlorococcus spp. dominated the upper mixed layer, accounting for 50–60% of its estimated primary production both inside and outside of Opal. In contrast, the deep zone of 70–90 m showed little evidence of growth rate enhancement and was principally defined by a 100-fold increase of large (>20-μm) diatoms and a shift from Prochlorococcus to diatom dominance (80%) of production. The intermediate layer of 50–60 m marked the transition between the upper and lower extremes but also contained an elevated biomass of physiologically unhealthy diatoms with significantly depressed growth rates and proportionately greater grazing losses relative to diatoms above or below. Microzooplankton grazers consumed 58%, 65% and 55%, respectively, of the production of diatoms, Prochlorococcus and the total phytoplankton community in Cyclone Opal. The substantial grazing impact on diatoms suggests that efficient recycling was the major primary fate of diatom organic production, consistent with the low export fluxes and selective export of biogenic silica, as empty diatom frustules, in Cyclone Opal.  相似文献   

Spectral modification and geographic redistribution of the semi-diurnal internal tide     

Harper L. Simmons   《Ocean Modelling》2008,21(3-4):126-138

A realistic-geometry global baroclinic tidal model forced with a single tidal constituent $(M_2)$ is used to investigate the generation of the internal tide and the associated radiated baroclinic energy flux. The model internal wave spectrum is populated at discrete frequency multiples $(1/2\text{,}1\text{,}3/2\text{,}2\text{,}5/2\text{,}\dots )$ of $M_2$. The $1/2M_2$ subharmonic is particularly energetic at its turning latitude of $\pm 28.8°$. Poleward only integer superharmonics of $M_2$ are significantly excited. The subharmonic turning latitude (SHTL) disturbance has high vertical wavenumber and shear, provided that internal tide energy level exceeds a threshold value. Under these circumstances, Richardson numbers smaller than 1/4 occur in the upper few hundred meters in both the realistic-geometry model and in a complimentary idealized geometry two-dimensional (2D) model. In the 2D model, the disturbance enables Richardson number dependent diapycnal entrainment to effect a modification of the stratification of the upper 400 m of the ocean, and poleward cross-SHTL energy flux falls to 10% of its pre-instability value due to energy transfer to the non-propagating (i.e., inertial) subharmonic. Realistic-geometry simulations suggest a more modest 40% decrease in net flux, although the strongest beams are almost entirely shut down. The predicted energy flux-convergence implies a thermocline dissipation rate in the 28.5–30.0°N latitude band of $5\times {10}^{-9}\text{W}{\text{kg}}^{-1}$, with an associated diapycnal diffusivity of ${10}^{-4}{\text{m}}^2{\text{s}}^{-1}$. North of Hawaii the implied regional dissipation rate reaches $4\times {10}^{-8}\text{W}{\text{kg}}^{-1}$ with an associated thermocline diffusivity of $8\times {10}^{-4}{\text{m}}^2{\text{s}}^{-1}$. Investigations of subgridscale parameterization and resolution sensitivity suggest that the basic character and magnitude of the predictions are robust to details of the numerical solutions. The present results are taken as further evidence that an increase in shear-driven turbulent mixing in the upper ocean is predicted at special latitudes. It is suggested that the search should be directed to regions where intense low-mode internal tide beams cross their subharmonic turning latitude.  相似文献   

Progress in NTHMP Hazard Assessment     

Frank I. González  Vasily V. Titov  Harold O. Mofjeld  Angie J. Venturato  R. Scott Simmons  Roger Hansen  Rodney Combellick  Richard K. Eisner  Don F. Hoirup  Brian S. Yanagi  Sterling Yong  Mark Darienzo  George R. Priest  George L. Crawford  Timothy J. Walsh 《Natural Hazards》2005,35(1):89-110

The Hazard Assessment component of the U.S. National Tsunami Hazard Mitigation Program has completed 22 modeling efforts covering 113 coastal communities with an estimated population of 1.2 million residents that are at risk. Twenty-three evacuation maps have also been completed. Important improvements in organizational structure have been made with the addition of two State geotechnical agency representatives to Steering Group membership, and progress has been made on other improvements suggested by program reviewers.  相似文献