Imposex as a biomonitoring tool for marine pollution by tributyltin: some further observations

Imposex, i.e., the imposition of male sexual characteristics on female neograstropods, has been used worldwide as a bioindicator of pollution by the antifouling agent TBT as well as to assess the related ecological impact. The recent total ban on the use of TBT in the maritime industry has been partly based on the use of such a biomarker. This is mainly based on the assumption that no other pollutant, or environmental stress, is able to induce such a biological response. Nonetheless, several authors had challenged this idea. The present paper will present further field observations on imposex in Hexaplex trunculus from Malta (Central Mediterranean) which may help clarify this issue. Furthermore, the incidence of imposex in this species will be related to body burdens and to the environmental levels of organotins as measured analytically. First histological observations will also be presented which may help clarify the ecological significance of this response in this species. Finally a number of alternative scenarios regarding the relationship between imposex and TBT will be discussed.     

Water farms and transfer conflicts in Arizona,USA: A proposed resolution process

Water is a relatively scarce resource in Arizona, especially since the recent urban growth booms of Phoenix and Tucson. Arizona's 1980 Groundwater Management Act was the precursor to current water-transfer conflicts between urban buyers, rural farmers, and third parties. Water farms are bought with the intention to transfer their appurtenant groundwater to the two major metropolitan areas. As water markets have emerged, differing values and public interest issues have become apparent, while the state legislature attempts to resolve inequities. Site-specific transfer disputes, as well as policy-making conflicts, offer suitable situations for a mediation process. Equity- and efficiency-based criteria are suggested as the basis for resolving water-transfer conflicts, and a mediation process is proposed. However, third parties must develop an agenda, and a balance of power should be attained before mediation can effectively forge an agreement on water-transfer policies. The attainment of statewide policies generated through a mediated process has the potential to expand long-range regional water planning and management.     

VALUATION OF IMPROVED IRRIGATION EFFICIENCY FROM AN EXHAUSTIBLE GROUNDWATER SOURCE1

This paper presents estimates made via a recursive linear programming model of the net benefits of improving irrigation application efficiency from an exhaustible groundwater source. Net benefits were derived for different application efficiency levels under furrow, sprinkler, and LEPA irrigation systems. In addition, net benefit estimates were obtained for the transition across irrigation systems. Solutions from the model indicate that low crop prices have a differential impact on net benefits across irrigation application efficiencies and irrigation systems. Also, the more limited groundwater situations consistently reduce the economic incentive to adopt improved irrigation application techniques across all irrigation systems.     

A SEPARABLE LINEAR ALGORITHM FOR HYDROPOWER OPTIMIZATION1

ABSTRACT: A deterministic, separable, linear algorithm is presented for maximizing aggregate hydropower production. The method is iterative and amenable to solution using standard LP software. The utility of the technique is demonstrated using several test applications involving a hypothetical single-purpose hydropower reservoir and a monthly increment 20-year flow record from the Gunpowder River in Maryland. The separable linearized forms solved quickly using MPSX on a variety of IBM hardware: 3090-400 VF, 3084 QX, dual processor 4381-3, and an AT/370 personal computer. For comparison purposes, the original nonlinear nonseparable version of the model was also solved using MINOS. This yielded a value of aggregate hydropower marginally higher than that using MPSX. The separable, linearized methodology proved to be a useful and an efficient means of generating good starting points for MINOS. The use of these warm starts effected substantial reductions in MINOS execution times.     

Raptor responses to low-level jet aircraft and sonic booms

We estimated effects of low-level military jet aircraft and mid- to high-altitude sonic booms (actual and simulated) on nesting peregrine falcons (Falco peregrinus) and seven other raptors by observing their responses to test stimuli, determining nesting success for the test year, and evaluating site reoccupancy rates for the year following the tests. Frequent and nearby jet aircraft passes: (1) sometimes noticeably alarmed birds, (2) occasionally caused birds to fly from perches or eyries, (3) most often evoked only minimal responses, and (4) were never associated with reproductive failure. Similarly, responses to real and simulated mid- to high-altitude sonic booms were often minimal and never appeared productivity limiting. Eighteen (95%) of 19 nest sites subjected to low-level jet flights and/or simulated sonic booms in 1980 fledged young during that year. Eighteen (95%) of 19 sites disturbed in 1980 were reoccupied by pairs or lone birds of the same species in 1981. We subjected four pairs of prairie falcons (Falco mexicanus) to low-level aircraft at ad libitum levels during the courtship and incubation phases when adults were most likely to abandon: all four eyries fledged young. From heart rate (HR) data taken via a telemetering egg at another prairie falcon eyrie, we determined that stimulus-induced HR alterations were comparable to rate changes for birds settling to incubate following flight. While encouraging, our findings cannot be taken as conclusive evidence that jet flights and/or sonic booms will have no long-term negative effects for other raptor species or for other areas. In addition, we did not experiment with totally naive wild adults, rotary-winged aircraft, or low-level sonic booms.     

Relationships between psychological climate perceptions and work outcomes: a meta‐analytic review

In this study, meta‐analytic procedures were used to examine the relationships between individual‐level (psychological) climate perceptions and work outcomes such as employee attitudes, psychological well‐being, motivation, and performance. Our review of the literature generated 121 independent samples in which climate perceptions were measured and analyzed at the individual level. These studies document considerable confusion regarding the constructs of psychological climate, organizational climate, and organizational culture and reveal a need for researchers to use terminology that is consistent with their level of measurement, theory, and analysis. Our meta‐analytic findings indicate that psychological climate, operationalized as individuals' perceptions of their work environment, does have significant relationships with individuals' work attitudes, motivation, and performance. Structural equation modeling analyses of the meta‐analytic correlation matrix indicated that the relationships of psychological climate with employee motivation and performance are fully mediated by employees' work attitudes. We also found that the James and James ( 1989 ) PC_g model could be extended to predict the impact of work environment perceptions on employee attitudes, motivation, and performance. Despite the number of published individual‐level climate studies that we found, there is a need for more research using standardized measures so as to enable analyses of the organizational and contextual factors that might moderate the effects of psychological climate perceptions. Finally, we argue for a molar theory of psychological climate that is rooted in the psychological processes by which individuals make meaning or their work experiences. Copyright © 2003 John Wiley & Sons, Ltd.     

Prediction of contaminant transport in fractured carbonate aquifer types: a case study of the Permian Magnesian Limestone Group (NE England,UK)

Viruses and bacteria which are characterized by finite lives in the subsurface are rapidly transported via fractures and cavities in fractured and karst aquifers. Here, we demonstrate how the coupling of a robust outcrop characterization and hydrogeophysical borehole testing is essential for prediction of contaminant velocities and hence wellhead protection areas. To show this, we use the dolostones of the Permian Magnesian Limestone aquifer in NE England, where we incorporated such information in a groundwater flow and particle tracking model. Within this aquifer, flow in relatively narrow (mechanical aperture of ~?10^?1–1 mm) fractures is coupled with that in pipe cavities (~?0.20-m diameter) following normal faults. Karstic cavities and narrow fractures are hydraulically very different. Thus, the solutional features are represented within the model by a pipe network (which accounts for turbulence) embedded within an equivalent porous medium representing Darcian flowing fractures. Incorporation of fault conduits in a groundwater model shows that they strongly influence particle tracking results. Despite this, away from faulted areas, the effective flow porosity of the equivalent porous medium remains a crucial parameter. Here, we recommend as most appropriate a relatively low value of effective porosity (of 2.8?×?10^?4) based on borehole hydrogeophysical testing. This contrasts with earlier studies using particle tracking analyses on analogous carbonate aquifers, which used much higher values of effective porosity, typically ~?10² times higher than our value, resulting in highly non-conservative estimates of aquifer vulnerability. Low values of effective flow porosities yield modelled flow velocities ranging from ~?100 up to ~?500 m/day in un-faulted areas. However, the high fracturing density and presence of karstic cavities yield modelled flow velocities up to ~?9000 m/day in fault zones. The combination of such flow velocities along particle traces results in 400-day particle traces up to 8-km length, implying the need for large well protection areas and high aquifer vulnerability to slowly degrading contaminants.