Effects of Small-Scale Armoring and Residential Development on the Salt Marsh-Upland Ecotone     

Alyssa-Lois M. Gehman  Natalie A. McLenaghan  James E. Byers  Clark R. Alexander  Steven C. Pennings  Merryl Alber 《Estuaries and Coasts》2018,41(1):54-67

Small-scale armoring placed near the marsh-upland interface to protect single-family homes is widespread but understudied. Using a nested, spatially blocked sampling design on the coast of Georgia, USA, we compared the biota and environmental characteristics of 60 marshes adjacent to either a bulkhead, a residential backyard with no armoring, or an intact forest. We found that marshes adjacent to bulkheads were at lower tidal elevations and had features typical of lower elevation marsh habitats: high coverage of the marsh grass Spartina alterniflora, high density of crab burrows, and muddy sediments. Marshes adjacent to unarmored residential sites had higher soil water content and lower porewater salinities than the armored or forested sites, suggesting that there may be increased freshwater input to the marsh at these sites. Deposition of Spartina wrack on the marsh-upland ecotone was negatively related to elevation at armored sites and positively related at unarmored residential and forested sites. Armored and unarmored residential sites had reduced densities of the high marsh crab Armases cinereum, a species that moves readily across the ecotone at forested sites, using both upland and high marsh habitats. Distance from the upland to the nearest creek was longest at forested sites. The effects observed here were subtle, perhaps because of the small-scale, scattered nature of development. Continued installation of bulkheads in the southeast could lead to greater impacts such as those reported in more densely armored areas like the northeastern USA. Moreover, bulkheads provide a barrier to inland marsh migration in the face of sea level rise. Retaining some forest vegetation at the marsh-upland interface and discouraging armoring except in cases of demonstrated need could minimize these impacts.  相似文献   

Tetrachloroethene Release and Degradation During Combined ERH and Sodium Persulfate Oxidation          下载免费PDF全文

Tyler Marcet  Natalie L. Cápiro  Kurt D. Pennell 《Ground Water Monitoring & Remediation》2017,37(4):43-50

Electrical resistance heating (ERH) is a thermal treatment technology that involves passing electrical current through soil to increase subsurface temperatures. In addition to volatizing and recovering contaminant mass in the gas phase, heating the subsurface has the potential to decompose contaminants by increasing the rate of degradation reactions. Prior laboratory studies using convective heating demonstrated that the rate of tetrachloroethene (PCE) degradation was not sufficient to cause substantial in situ PCE mass destruction. However, similar experiments have not been performed using ERH, which has the potential to degrade PCE in reaction with the heating electrodes and electrochemically. Thus, the objective of this study was to determine the extent of PCE degradation during thermal treatment of PCE‐contaminated soil using a bench‐scale ERH system. The contaminated soil, a silty clay loam, was collected from a single borehole at a former dry cleaning facility prior to undergoing ERH treatment. After 30 days of ERH, 52% of the initial PCE mass was recovered, potentially indicating that 48% of the PCE was degraded during ERH. Although potential degradation products such as carbon dioxide were observed, their presence was attributed to the degradation of soil organic carbon and carbonates rather than PCE destruction. A second ERH experiment was conducted to assess the potential benefit of adding the heat‐activated oxidant, sodium‐persulfate, during treatment. After 19 days of ERH and three persulfate injections, 93% of the initial PCE was recovered, with 3% PCE destruction based on chloride evolution. However, the difference in mass recovery between the first and second experiments could have been due to differences in the initial mass of PCE, even though soil from the same core was used in both experiments. The results of this work suggest that the majority of mass recovered during ERH of the PCE‐contaminated soil at the former dry cleaning facility will be due to volatilization and gas phase extraction rather than abiotic degradation, even with the addition of sodium persulfate.  相似文献   

Rainfall interception by tree crown and leaf litter: An interactive process   总被引：1，自引：0，他引：1       下载免费PDF全文

Xiang Li  Qingfu Xiao  Jianzhi Niu  Salli Dymond  E. Gregory McPherson  Natalie van Doorn  Xinxiao Yu  Baoyuan Xie  Kebin Zhang  Jiao Li 《水文研究》2017,31(20):3533-3542

Rainfall interception research in forest ecosystems usually focuses on interception by either tree crown or leaf litter, although the 2 components interact when rainfall occurs. A process‐based study was conducted to jointly measure rainfall interception by crown and litter and the interaction between the 2 interception processes for 4 tree species (Platycladus orientalis and Pinus tabulaeformis represented needle‐leaf species, and Quercus variabilis and Acer truncatum represented broadleaf species) at 3 simulated rainfall intensities (10, 50, and 100 mm hr^?1). Results indicated that (a) crown and litter interception processes incorporated 3 phases: the dampening phase, the steady saturation phase, and the postrainfall drainage phase, but the dampening phase for litter interception usually lasted 30 min longer than for crown interception; (b) the maximum and minimum interception storage (C _max and C _min ) for the crown were 0.63 and 0.36 mm on average, and litter C _max and C _min were 5.38 and 2.36 mm, respectively; (c) generally, crown and litter C _max and C _min increased when gross precipitation increased significantly (p  < .05) from 10 to 100 mm; and (4) crown C _max and C _min for needle‐species were 1.8 and 1.2 times larger than broadleaf species, whereas broadleaf litter showed the opposite, its C _max and C _min were 2.0 and 1.6 times larger than needle‐leaf litter on average; however, no significant differences were observed in crown and litter C _max and C _min between species on per leaf area and litter thickness basis. Results were normalized by total leaf area and litter thickness to provide a way to scale up from young trees to mature forests. Overall, rainfall interception was affected by biotic and abiotic factors together and could be quantified via multiple linear regression functions.  相似文献   

Stakeholder objective preferences in Australian Commonwealth managed fisheries     

Sean Pascoe  Wendy Proctor  Chris Wilcox  James Innes  Wayne Rochester  Natalie Dowling 《Marine Policy》2009,33(5):750-758

Fisheries management is increasingly involving a wide range of stakeholders in the decision making process. However, in most fisheries, the set of management objectives are poorly defined, and the implicit importance placed on these objectives may vary considerably both between and within different stakeholder groups. This may lead to conflicts within management advisory groups where members from different stakeholder groups view potential management outcomes substantially differently, and inconsistencies in decision making when changes in stakeholder representation take place. In this paper, the institutional structure of fisheries management in Australia and the roles the different organisations play in shaping fisheries management plans are detailed. An explicit hierarchy of management objectives is developed in collaboration with key managers and policy makers. A large survey of stakeholders involved in Australian Commonwealth fisheries management was undertaken to determine stakeholder preferences relating to these objectives. The results highlight the differences in perspectives regarding the relative importance of the multiple objectives of fisheries management. While on average stakeholder preferences generally correspond with their expected preference set, the results also indicate that there is generally low coherence within stakeholder groups.  相似文献   

Multidecadal biological monitoring and abatement program\ assessing human impacts on aquatic ecosystems within the Oak Ridge Reservation in eastern Tennessee,USA     

Paul G. Matson  Louise M. Stevenson  Natalie A. Griffiths  Christopher R. DeRolph  R. Trent Jett  Allison M. Fortner  Michael W. Jones  Nikki J. Jones  Teresa J. Mathews 《水文研究》2021,35(9):e14340

Human activities can be powerful drivers of ecosystem change within catchments. While most long-term catchment studies have been conducted at pristine sites, such studies are less common from sites more impacted by human activity. The Oak Ridge National Laboratory's Biological Monitoring and Abatement Program (BMAP) was developed in the mid-1980s to (1) assess compliance with environmental regulations, (2) identify causes of adverse ecological impacts, (3) provide data for human and ecological risk assessments, and (4) evaluate the effectiveness of remedial actions taken to mitigate the impacts of contaminants in soils, groundwater, and surface water by documenting ecological recovery on the Oak Ridge Reservation (ORR), a federally owned 33 476-acre site in eastern Tennessee, managed by the US Department of Energy. The ORR is composed of multiple watersheds containing many small to mid-size streams. BMAP uses an integrated approach for determining stream health; its databases include long-term seasonal records of contaminant concentrations in water and biota, data from aquatic toxicity testing, and surveys of macroinvertebrate and fish assemblages from impacted and reference streams. These long-term data provide valuable records of degradation and recovery in catchment ecosystems. Our objective here is to describe our study system and data series in order to increase awareness of the availability of these long-term data to the catchment science community.  相似文献   

Risk management tools for sustainable fisheries management under changing climate: a sea cucumber example     

Éva E. Plagányi  Timothy D. Skewes  Natalie A. Dowling  Malcolm Haddon 《Climatic change》2013,119(1):181-197

Sustainable fisheries management into the future will require both understanding of and adaptation to climate change. A risk management approach is appropriate due to uncertainty in climate projections and the responses of target species. Management strategy evaluation (MSE) can underpin and support effective risk management. Climate change impacts are likely to differ by species and spatially. We use a spatial MSE applied to a multi-species data-poor sea cucumber/béche-de-mer fishery to demonstrate the utility of MSE to test the performance of alternative harvest strategies in meeting fishery objectives; this includes the ability to manage through climate variability and change, and meeting management objectives pertaining to resource status and fishery economic performance. The impacts of fishing relative to the impacts of climate change are distinguished by comparing future projection distributions relative to equivalent no-fishing no-climate-change trials. The 8 modelled species exhibit different responses to environmental variability and have different economic value. Status quo management would result in half the species falling below target levels, moderate risks of overall and local depletion, and significant changes in species composition. The three simple strategies with no monitoring (spatial rotation, closed areas, multi-species composition) were all successful in reducing these risks, but with fairly substantial decreases in the average profit. Higher profits (for the same risk levels) could only be achieved with strategies that included monitoring and hence adaptive management. Spatial management approaches based on adaptive feedback performed best overall.  相似文献   

The impacts of climate change on tribal traditional foods     

Kathy Lynn  John Daigle  Jennie Hoffman  Frank Lake  Natalie Michelle  Darren Ranco  Carson Viles  Garrit Voggesser  Paul Williams 《Climatic change》2013,120(3):545-556

American Indian and Alaska Native tribes are uniquely affected by climate change. Indigenous peoples have depended on a wide variety of native fungi, plant and animal species for food, medicine, ceremonies, community and economic health for countless generations. Climate change stands to impact the species and ecosystems that constitute tribal traditional foods that are vital to tribal culture, economy and traditional ways of life. This paper examines the impacts of climate change on tribal traditional foods by providing cultural context for the importance of traditional foods to tribal culture, recognizing that tribal access to traditional food resources is strongly influenced by the legal and regulatory relationship with the federal government, and examining the multi-faceted relationship that tribes have with places, ecological processes and species. Tribal participation in local, regional and national climate change adaption strategies, with a focus on food-based resources, can inform and strengthen the ability of both tribes and other governmental resource managers to address and adapt to climate change impacts.  相似文献   

A universal field equation for dispersive processes in heterogeneous media     

John H. Cushman  Moongyu Park  Monica Moroni  Natalie Kleinfelter-Domelle  Daniel O��Malley 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(1):1-10

When formulated properly, most geophysical transport-type process involving passive scalars or motile particles may be described by the same space–time nonlocal field equation which consists of a classical mass balance coupled with a space–time nonlocal convective/dispersive flux. Specific examples employed here include stretched and compressed Brownian motion, diffusion in slit-nanopores, subdiffusive continuous-time random walks (CTRW), super diffusion in the turbulent atmosphere and dispersion of motile and passive particles in fractal porous media. Stretched and compressed Brownian motion, which may be thought of as Brownian motions run with nonlinear clocks, are defined as the limit processes of a special class of random walks possessing nonstationary increments. The limit process has a mean square displacement that increases as t^α+1 where α > −1 is a constant. If α = 0 the process is classical Brownian, if α < 0 we say the process is compressed Brownian while if α > 0 it is stretched. The Fokker–Planck equations for these processes are classical ade’s with dispersion coefficient proportional to t^α. The Brownian-type walks have fixed time step, but nonstationary spatial increments that are Gaussian with power law variance. With the CTRW, both the time increment and the spatial increment are random. The subdiffusive Fokker–Planck equation is fractional in time for the CTRW’s considered in this article. The second moments for a Levy spatial trajectory are infinite while the Fokker–Planck equation is an advective–dispersive equation, ade, with constant diffusion coefficient and fractional spatial derivatives. If the Lagrangian velocity is assumed Levy rather than the position, then a similar Fokker–Planck equation is obtained, but the diffusion coefficient is a power law in time. All these Fokker–Planck equations are special cases of the general non-local balance law.  相似文献   

利用卫星图像分析南京信息工程大学校园变化特征     

李旭辉  赵佳玉  Natalie Schultz  肖薇  刘寿东 《南京气象学院学报》2020,12(1):7-21

本文主要目的是利用卫星图像资料分析南京信息工程大学（Nanjing University of Information Science and Technology,NUIST）建校之初至今校园的变化特征.共分析了1964年11月至1970年12月之间的5幅无云的美国侦察卫星图像（1995年解密）,地理配准后图像的位置精度为4.8至7.8 m,图像中的建筑物、道路和水体都清晰可见.通过对比这些黑白的侦察卫星图像与2006—2018年的Google Earth彩色图像,发现现在校园面积远远大于旧校园;旧图像里中苑老操场跑道长度为298 m,2006年Google Earth图像中为406.5 m,操场中心点向东移动了9 m,向南移动了47 m.侦察卫星图像和Google Earth图像都是以统一坐标系做地理位置校正,相关图像见附件.  相似文献   

Paleoecology of mangroves along the Sibun River, Belize     

Natalie M. Monacci  Ursula Meier-Grünhagen  Bruce P. Finney  Hermann Behling  Matthew J. Wooller 《Quaternary Research》2011,76(2):220-228

This study examines a sediment core (SR-63) from a mangrove ecosystem along the Sibun River in Belize, which is subject to both changes in sea-level and in the characteristics of the river's drainage basin. Radiocarbon dates from the core show a decreased sedimentation rate from ~ 6 ka to 1 cal ka BP and a marked change in lithology from primarily mangrove peat to fluvial-derived material at ~ 2.5 cal ka BP. Changes in the sedimentation rates observed in mangrove ecosystems offshore have previously been attributed to changes in relative sea-level and the rate of sea-level rise. Pollen analyses show a decreased abundance of Rhizophora (red mangrove) pollen and an increased abundance of Avicennia (black mangrove) pollen and non-mangrove pollen coeval with the decreased sedimentation rates. Elemental ratios ([N:C]_a) and stable isotope analyses (δ¹⁵N and δ¹³C) show that changes in the composition of the organic material are also coeval with the change in lithology. The decrease in sedimentation rate at the site of core SR-63 and at offshore sites supports the idea that regional changes in hydrology occurred during the Holocene in Belize, influencing both mainland and offshore mangrove ecosystems.  相似文献