Contamination,risk, and heterogeneity: on the effectiveness of aquifer remediation     

Reed M. Maxwell  Steven F. Carle  Andrew F. B. Tompson 《Environmental Geology》2008,54(8):1771-1786

The effectiveness of aquifer remediation is typically expressed in terms of a reduction in contaminant concentrations relative to a regulated maximum contaminant level (MCL), and is usually confirmed by sparse monitoring data and/or simple model calculations. Here, the effectiveness of remediation is re-examined from a more thorough risk-based perspective that goes beyond the traditional MCL concept. A methodology is employed to evaluate the health risk to individuals exposed to contaminated household water that is produced from groundwater. This approach explicitly accounts for differences in risk arising from variability in individual physiology and water use, the uncertainty in estimating chemical carcinogenesis for different individuals, and the uncertainties and variability in contaminant concentrations within groundwater as affected by transport through heterogeneous geologic media. A hypothetical contamination scenario is developed as a case study in a saturated, alluvial aquifer underlying an actual Superfund site. A baseline (unremediated) human exposure and health risk scenario, as induced by contaminated groundwater pumped from this site, is predicted and compared with a similar estimate based upon pump-and-treat exposure intervention. The predicted reduction in risk in the remediation scenario is not an equitable one—that is, it is not uniform to all individuals within a population and varies according to the level of uncertainty in prediction. The importance of understanding the detailed hydrogeologic connections that are established in the heterogeneous geologic regime between the contaminated source, municipal receptors, and remediation wells, and its relationship to this uncertainty is demonstrated. Using two alternative pumping rates, we develop cost-benefit curves based upon reduced exposure and risk to different individuals within the population, under the presence of uncertainty.  相似文献   

Community ecology of the metazoan parasites of snoek Thyrsites atun (Euphrasen, 1791) (Perciformes: Gempylidae) off South Africa     

MAI Nunkoo  CC Reed  SE Kerwath 《African Journal of Marine Science》2016,38(3):363-371

The parasite assemblage of snoek Thyrsites atun, a commercially important fish in the Benguela system, was examined over a one-year period. In all, 16 parasite taxa including eight new host records (Bolbosoma vasculosum, Caligus coryphaenae, Caligus dakari, Corynosoma australe, Hatschekia conifera, Nothobomolochus fradei, Rhadinorhynchus cadenati, Tentacularia coryphaenae) and four new locality records (B. vasculosum, C. dakari, Molicola uncinatus, Pseudoterranova sp.) were recovered from 210 specimens. The dominance of larval helminths in the component community suggests that T. atun occupies an intermediate position in the food web. The ‘nestedness metric based on overlap and decreasing fill’ (NODF) indicated that the parasite assemblage exhibited no nestedness (NODF = 73.3, p = 0.103). Generalised additive mixed modelling results indicated that host length is the main determinant of parasite species richness in T. atun. PERMANOVA and ANOSIM suggested that infracommunity structure varied little with respect to the sex, length, seasonality and capture region of the host. The stability and randomness in parasite acquisition, as indicated by the lack of nestedness of the parasite assemblage, can be ascribed to the opportunistic feeding behaviour and nomadic movement of T. atun in the southern Benguela. The homogeneity of the community structure of long-lived endoparasites suggests that a single T. atun stock occurs off South Africa.  相似文献   

Palaeozoic suturing of eastern and western Tasmania in the west Tamar region: Implications for the tectonic evolution of southeast Australia     

A. R. Reed  C. Calver  R. S. Bottrill 《Australian Journal of Earth Sciences》2013,60(5):809-830

A new tectonic model for Tasmania incorporates subduction at the boundary between eastern and western Tasmania. This model integrates thin‐ and thick‐skinned tectonics, providing a mechanism for emplacement of allochthonous elements on to both eastern and western Tasmania as well as rapid burial, metamorphism and exhumation of high‐pressure metamorphic rocks. The west Tamar region in northern Tasmania lies at the boundary between eastern and western Tasmania. Here, rocks in the Port Sorell Formation were metamorphosed at high pressures (700–1400 MPa) and temperatures (400–500°C), indicating subduction to depths of up to 30 km. The eastern boundary of the Port Sorell Formation with mafic‐ultramafic rocks of the Andersons Creek Ultramafic Complex is hidden beneath allochthonous ?Mesoproterozoic turbidites of the Badger Head Group. At depth, this boundary coincides with the inferred boundary between eastern and western Tasmania, imaged in seismic data as a series of east‐dipping reflections. The Andersons Creek Ultramafic Complex was previously thought of as allochthonous, based mainly on associations with other mafic‐ultramafic complexes in western Tasmania. However, the base of the Andersons Creek Ultramafic Complex is not exposed and, given its position east of the boundary with western Tasmania, it is equally likely that it represents the exposed western edge of autochthonous eastern Tasmanian basement. A thin sliver of faulted and metamorphosed rock, including amphibolites, partially separates the Badger Head Group from the Andersons Creek Ultramafic Complex. Mafic rocks in this package match geochemically mafic rocks in the Port Sorell Formation. This match is consistent with two structural events in the Badger Head Group showing tectonic transport of the group from the west during Cambrian Delamerian orogenesis. Rather than being subducted, emplacement of the Badger Head Group onto the Andersons Creek Ultramafic Complex indicates accretion of the Badger Head Group onto eastern Tasmania. Subsequent folding and thrusting in the west Tamar region also accompanied Devonian Tabberabberan orogenesis. Reversal from northeast to southwest tectonic vergence saw imbricate thrusting of Proterozoic and Palaeozoic strata, possibly coinciding with reactivation of the suture separating eastern and western Tasmania.  相似文献   

Formation of lode‐style gold mineralisation during Tabberabberan wrench faulting at Lefroy,eastern Tasmania     

A. Reed 《Australian Journal of Earth Sciences》2013,60(5):879-890

The Lefroy Goldfield in eastern Tasmania is anomalous in southeastern Australia because mineralised fault reefs (i.e. reefs that are also faults) strike in an easterly direction at a high angle to the predominantly northwest strike of bedding and folds. Gold mineralisation is of Early to Middle Devonian age, with reef formation coinciding with a third regionally compressive deformation event (D₃), and a second phase of Tabberabberan orogenesis. Mineralised reefs are hosted by Mathinna Supergroup turbidites of Cambrian to Ordovician age and extend for up to 2 km across the boundary between the sandstone‐dominated Stony Head Sandstone and the shale‐dominated Turquoise Bluff Slate. Ore shoots in the reefs plunge moderately west and, in the Volunteer Mine, coincide with the intersection of the reef and a D₁/D₂ thrust contact. The subvertical orientation and discordant relationship of the mineralised reefs to bedding, as well as the lack of gold mineralisation along bedding and pre‐D₃ structures, indicate that the reefs formed during a period of wrench faulting. In contrast to lode‐style deposits in Victoria, the far‐field minimum compressive stress at Lefroy during reef formation was not vertical but, rather, occupied a subhorizontal orientation.  相似文献   

Discovery of absorption features of the accretion disc corona and systematic acceleration of the X-ray burst rate in XB 1323-619     

M. J. Church  D. Reed  T. Dotani  M. Ba&#;uci&#;ska-Church  A. P. Smale 《Monthly notices of the Royal Astronomical Society》2005,359(4):1336-1344

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Factors Influencing Adoption and Implementation of Conservation Development Ordinances in Rural United States     

Heidi E. Kretser  Elliot Dale  Leslie Karasin  Liba Pejchar  Sarah E. Reed 《社会与自然资源》2019,32(9):1021-1039

Conservation Development (CD) is a land-use tool to reduce the impacts of development on natural resources, yetthe use of CD is highly variable. We used a collaborative conservation model to examine factors influencing adoption and implementation to improve the future application of CD. We interviewed 2–3 individuals including planners, board members, and developers (n?=?46) from 16 rural communities in the intermountain west and northeast U.S. Motivations to preserve rural character or comply with state statutes drove adoption. Greater capacity such as outside expertise, model regulations, and iterative revisions of ordinances was associated with stronger ordinances. Adoption processes including ample dialog across diverse constituents, especially those overseeing subdivision development, facilitated higher rates of implementation. Concerns over open space management, lack of successful CD examples, and inexperience with CD posed barriers to implementation. Understanding social context revealed the strengths and shortcomings of CD and provided guidance for strategically engaging communities in private lands conservation.  相似文献