Evaluating Tidal Wetland Restoration Performance Using National Estuarine Research Reserve System Reference Sites and the Restoration Performance Index (RPI)     

Kenneth B. Raposa  Scott Lerberg  Craig Cornu  John Fear  Nina Garfield  Christopher Peter  Robin L.J. Weber  Gregg Moore  David Burdick  Michelle Dionne 《Estuaries and Coasts》2018,41(1):36-51

Evaluations of tidal wetland restoration efforts suffer from a lack of appropriate reference sites and standardized methods among projects. To help address these issues, the National Estuarine Research Reserve System (NERRS) and the NOAA Restoration Center engaged in a partnership to monitor ecological responses and evaluate 17 tidal wetland restoration projects associated with five reserves. The goals of this study were to (1) determine the level of restoration achieved at each project using the restoration performance index (RPI), which compares change in parameters over time between reference and restoration sites, (2) compare hydrologic and excavation restoration projects using the RPI, (3) identify key indicator parameters for assessing restoration effectiveness, and (4) evaluate the value of the NERRS as reference sites for local restoration projects. We found that the RPI, modified for this study, was an effective tool for evaluating relative differences in restoration performance; most projects achieved an intermediate level of restoration from 2008 to 2010, and two sites became very similar to their paired reference sites, indicating that the restoration efforts were highly effective. There were no differences in RPI scores between hydrologic and excavation restoration project types. Two abiotic parameters (marsh platform elevation and groundwater level) were significantly correlated with vegetation community structure and thus can potentially influence restoration performance. Our results highlight the value of the NERRS as reference sites for assessing tidal wetland restoration projects and provide improved guidance for scientists and restoration practitioners by highlighting the RPI as a trajectory analysis tool and identifying key monitoring parameters.  相似文献   

Similarity-based approaches in hydrogeology: proposal of a new concept for data-scarce groundwater resource characterization and prediction     

Barthel  Roland  Haaf  Ezra  Giese  Markus  Nygren  Michelle  Heudorfer  Benedikt  Stahl  Kerstin 《Hydrogeology Journal》2021,29(5):1693-1709

Hydrogeology Journal - A new concept is proposed for describing, analysing and predicting the dynamic behaviour of groundwater resources based on classification and similarity. The concept makes...  相似文献   

Effects of temperature-dependent material properties and radioactive heat production on simple basin subsidence models     

Richard A. Ketcham  Eric C. Beam  Michelle A. Kominz 《Earth and Planetary Science Letters》1995,130(1-4):31-44

The effects of applying laboratory-derived material parameters to simple thermal basin subsidence models are examined. The temperature-dependent properties of thermal conductivity, specific heat and the coefficient of thermal expansion are considered, as well as conductivity contrasts between the crust and mantle and lithosphere-scale radiogenic heat production. The effects of conductivity and radioactivity are complementary, and can be predicted from the way in which they influence the initial and final steady-state geothermal gradient. A convex-up initial gradient, such as is generated by the conductivity and radioactivity functions and is also assumed to be the case based on independent evidence, will lead to more initial subsidence than in a simple constant-parameter model. The final subsidence will also be greater in the modified model, due to the fact that the stretching event will result in a lithospheric column which is intrinsically cooler than in the pre-deformation case. Because the coefficient of thermal expansion rises with increasing temperature, including its temperature dependence will result in a model with substantially less initial subsidence than one with a constant value. When these parameters are combined into a single model, the initial subsidence is approximately 15–20% less than in the constant-parameter model if radioactivity is not included, and 10% less if it is, while the final subsidence is about 5% greater without radioactivity and 7–9% greater with radioactivity included. Depending on the magnitude of extension, these effects can translate into differences of tens to hundreds of meters when compared to the constant-parameter model.  相似文献   

Reconstructing spatio-temporal patterns of debris-flow activity using dendrogeomorphological methods   总被引：2，自引：0，他引：2  

Michelle Bollschweiler  Markus Stoffel  Melanie Ehmisch  Michel Monbaron 《Geomorphology》2007,87(4):337-351

Debris flows are a major threat in many parts of the Alps, where they repeatedly cause severe damage to infrastructure and transportation corridors or even loss of life. Nonetheless, the spatial behavior of past debris-flow activity and the analysis of areas affected during particular events have been widely neglected in reconstructions so far. It was therefore the purpose of this study to reconstruct spatio-temporal patterns of past debris flows on a forested cone in the Swiss Alps (Bruchji torrent, Blatten, Valais). The analysis of past events was based on a detailed geomorphic map (1:1000) of all forms related to debris flows as well as on tree-ring series from 401 heavily affected trees (Larix decidua Mill. and Picea abies (L.) Karst.) growing in or next to deposits. The samples were analyzed and growth disturbances related to debris-flow activity assessed, such as tangential rows of traumatic resin ducts, the onset of reaction wood or abrupt growth suppression or release.In total, 960 growth disturbances were identified in the samples, belonging to 40 different event years between A.D. 1867 and 2005. In addition, the coupling of tree-ring data with the geomorphic map allowed reconstruction of eleven formerly active channels and spatial representation of individual events. Based on our results we believe that before 1935, debris flows preferentially used those channels located in the western part of the cone, whereas the eastern part of the cone remained widely unaffected. The spatial representation of the 40 events also allowed identification of five different spatial patterns for debris flows at the study site.  相似文献   

Micellar-Enhanced Ultrafiltration and Air Stripping for Surfactant-Contaminant Separation and Surfactant Reuse   总被引：2，自引：0，他引：2  

K. Michelle Lipe  David A. Sabatini  Mark A. Hasegawa  Jeffrey H. Harwell 《Ground Water Monitoring & Remediation》1996,16(1):85-92

Micellar-enhanced ultrafiltration (MELT) and air stripping were evaluated for surfactant-contaminant separation and surfactant recovery. Two linear alkyl diphenyloxide disulfonate (DPDS) surfactants were evaluated with the contaminants naphthalene and trichloroethylene. A separation model developed from micellar partitioning principles showed a good correlation to batch MEUF studies, whereas flux analysis highlighted concentration polarization effects in relation to hydrophobe length. MEUF effectively concentrated the surfactant-contaminant system (93 to 99 percent retention); however, this did not result in surfactant-contaminant separation. Batch and continuous flow air stripping models were developed based upon air/water ratio, surfactant concentration, and Micellar partitioning; model predictions were validated by experimental data. Sensitivity analyses illustrated the decline in contaminant-surfactant separation with increasing surfactant concentration (e.g., TCE removal efficiency declines from 83 percent to 37 percent as C-16 DPDS concentration increases from 0 to 55 mM). This effect is greater for more hydrophobic contaminants (naphthalene vs. TCE) and surfactants with greater solubilization potential (C16-DPDS vs. C-12 DPDS). The resulting design equations can account for this effect and thus properly size air strippers to achieve the desired removal efficiency in the presence of surfactant micelles. Proper selection and design of surfactant-contaminant separation and surfactant recovery systems are integral to optimizing surfactant-enhanced subsurface remediation.  相似文献   

Episodes of late Holocene aridity recorded by stalagmites from Devil's Icebox Cave, central Missouri, USA   总被引：1，自引：0，他引：1  

Rhawn F. Denniston  Michelle DuPree  Jeffrey A. Dorale  Victor J. Polyak 《Quaternary Research》2007,68(1):45-52

Two stalagmites from Devil's Icebox Cave, central Missouri, display similar δ¹³C and δ¹⁸O values and trends during the late Holocene. Positive δ¹³C excursions at 3.5-2.6 ka and 1.2-0.9 ka are interpreted to reflect drier conditions. These elevated stalagmite δ¹³C values could have plausibly been driven by increasing C₄ plant abundances over the cave or an increased contribution of bedrock carbon, both of which could reflect decreased effective moisture. A lack of corresponding oxygen isotopic anomalies during these intervals suggests that neither mean annual temperature nor the seasonality of precipitation changed concomitantly with dryness. Both of the δ¹³C excursions identified in our stalagmite record are roughly coincident with dry intervals from a number of sites located across the Great Plains.  相似文献   

The influence of human activity in the Arctic on climate and climate impacts   总被引：1，自引：0，他引：1  

Henry P. Huntington  Michelle Boyle  Gwenn E. Flowers  John W. Weatherly  Lawrence C. Hamilton  Larry Hinzman  Craig Gerlach  Rommel Zulueta  Craig Nicolson  Jonathan Overpeck 《Climatic change》2007,82(1-2):77-92

Human activities in the Arctic are often mentioned as recipients of climate-change impacts. In this paper we consider the more complicated but more likely possibility that human activities themselves can interact with climate or environmental change in ways that either mitigate or exacerbate the human impacts. Although human activities in the Arctic are generally assumed to be modest, our analysis suggests that those activities may have larger influences on the arctic system than previously thought. Moreover, human influences could increase substantially in the near future. First, we illustrate how past human activities in the Arctic have combined with climatic variations to alter biophysical systems upon which fisheries and livestock depend. Second, we describe how current and future human activities could precipitate or affect the timing of major transitions in the arctic system. Past and future analyses both point to ways in which human activities in the Arctic can substantially influence the trajectory of arctic system change.  相似文献   

A comparative mineralogical and geochemical study of sulfide mine tailings at two sites in New Mexico, USA   总被引：5，自引：0，他引：5  

Michelle P. Boulet  A. C. L. Larocque 《Environmental Geology》1998,33(2-3):130-142

A comparative study of sulfide mine tailings from two sites near Silver City in southwest New Mexico has shown the need for environmental monitoring in a geological context. The Cyprus-Piños Altos and Cleveland deposits consist of Cu and Zn skarn mineralization in the Piños Altos Mountains of New Mexico. Primary ore minerals in both deposits include chalcopyrite, sphalerite, and galena. The Cyprus-Piños Altos Mine ceased operation in 1995 and the Cleveland Mill closed in 1950. The deposits have similar mineralogical characteristics; however, the tailings are different in terms of age, degree of oxidation and method of disposal. The Cyprus-Piños Altos tailings (CPAT) are stored in a lined, bermed impoundment. They are dominantly water-saturated and exhibit no secondary-phase formation. The grains are not cemented and show no evidence of primary-mineral dissolution. The geochemical data show a predominantly primary signature. The tailings pond water is neutral to slightly alkaline (pH?from 7 to 8.3), partly as a result of processing methods. The Cleveland mill tailings (CMT) were deposited in a valley at the headwaters of an ephemeral stream. They are highly oxidized and differentially cemented. They have undergone numerous wet/dry cycles resulting in extensive oxidation. Secondary minerals predominate, and consist mainly of jarosite, goethite, hematite, and Fe-oxyhydroxides and -oxyhydroxysulfates. The pH of the stream draining the CMT is as high as 2.15. Maximum metal contents in the stream immediately downstream from the tailings are 5305?ppm Zn, 454?ppm Cu, 1.16?ppm Pb, 17.5?ppm Cd, 1.4?ppm As, and 0.01?ppm Hg.  相似文献   

Environmental effects on the reproduction and fecundity of the introduced calcareous sponge Paraleucilla magna in Rio de Janeiro,Brazil          下载免费PDF全文

Emilio Lanna  Rodolfo Paranhos  Paulo C. Paiva  Michelle Klautau 《Marine Ecology》2015,36(4):1075-1087

The calcareous sponge Paraleucilla magna (Porifera, Calcarea) has been the subject of several studies in the last decade. It was first described along the Brazilian coast, where it is considered cryptogenic, and was subsequently found in the Mediterranean, where it is considered invasive. The wide artificial distribution of this species allows us to compare different aspects of the biology of an introduced species in different locations. Here, we analysed the effects of selected environmental parameters on the reproductive dynamics of P. magna in Rio de Janeiro (Brazil) over 18 months and compared our results with those obtained for the same species in the Mediterranean Sea. Specimens were collected monthly and analysed through histological methods. The density of reproductive elements in each month was calculated, and the effects of environmental parameters (photoperiod, precipitation, temperature, phytoplankton and bacterioplankton) were analysed using a regression tree analysis. Paraleucilla magna was reproductive throughout the study period. The densities of the reproductive elements (oocytes, embryos and larvae) showed no seasonality, and this species presented one of the highest reproductive efforts documented to date in the phylum Porifera (99.0 oocytes · mm^?3; 89.0 embryos · mm^?3; 319.0 larvae · mm^?3). The main environmental parameters related to the reproduction of P. magna were temperature, photoperiod and bacterioplankton. Temperature was the main driver associated with the densities of oocytes and embryos, while bacterioplankton was the main driver of larvae (positive relationships). In Rio de Janeiro, larvae were present and continuously released. This strategy is different from that observed in the Mediterranean, where a larger larval output was observed but only during the summer months. Our results show that P. magna is a species with a strong invasive potential, considering its high and continuous reproductive effort. This high fecundity stimulated by high temperatures may be a key factor contributing to the growth of P. magna populations and its invasion of new areas.  相似文献   

Setting nutrient thresholds to support an ecological assessment based on nutrient enrichment, potential primary production and undesirable disturbance     

Devlin M  Painting S  Best M 《Marine pollution bulletin》2007,55(1-6):65-73

The EU Water Framework Directive recognises that ecological status is supported by the prevailing physico-chemical conditions in each water body. This paper describes an approach to providing guidance on setting thresholds for nutrients taking account of the biological response to nutrient enrichment evident in different types of water. Indices of pressure, state and impact are used to achieve a robust nutrient (nitrogen) threshold by considering each individual index relative to a defined standard, scale or threshold. These indices include winter nitrogen concentrations relative to a predetermined reference value; the potential of the waterbody to support phytoplankton growth (estimated as primary production); and detection of an undesirable disturbance (measured as dissolved oxygen). Proposed reference values are based on a combination of historical records, offshore (limited human influence) nutrient concentrations, literature values and modelled data. Statistical confidence is based on a number of attributes, including distance of confidence limits away from a reference threshold and how well the model is populated with real data. This evidence based approach ensures that nutrient thresholds are based on knowledge of real and measurable biological responses in transitional and coastal waters.  相似文献