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61.
62.
Influence of Riparian Seepage Zones on Nitrate Variability in Two Agricultural Headwater Streams
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Mark R. Williams Anthony R. Buda Herschel A. Elliott Kamini Singha James Hamlett 《Journal of the American Water Resources Association》2015,51(4):883-897
Riparian seeps have been recognized for their contributions to stream flow in headwater catchments, but there is limited data on how seeps affect stream water quality. The objective of this study was to examine the effect of seeps on the variability of stream NO3‐N concentrations in FD36 and RS, two agricultural catchments in Pennsylvania. Stream samples were collected at 10‐m intervals over reaches of 550 (FD36) and 490 m (RS) on 21 occasions between April 2009 and January 2012. Semi‐variogram analysis was used to quantify longitudinal patterns in stream NO3‐N concentration. Seep water was collected at 14 sites in FD36 and 7 in RS, but the number of flowing seeps depended on antecedent conditions. Seep NO3‐N concentrations were variable (0.1‐29.5 mg/l) and were often greater downslope of cropped fields compared to other land uses. During base flow, longitudinal variability in stream NO3‐N concentrations increased as the number of flowing seeps increased. The influence of seeps on the variability of stream NO3‐N concentrations was less during storm flow compared to the variability of base flow NO3‐N concentrations. However, 24 h after a storm in FD36, an increase in the number of flowing seeps and decreasing streamflow resulted in the greatest longitudinal variability in stream NO3‐N concentrations recorded. Results indicate seeps are important areas of NO3‐N delivery to streams where targeted adoption of mitigation measures may substantially improve stream water quality. 相似文献
63.
Resolution and Analysis of Spatial Variations and Patterns in an Urban Lake with Rapid Profiling Instrumentation
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Anthony R. Prestigiacomo Steven W. Effler David A. Matthews 《Journal of the American Water Resources Association》2015,51(1):200-213
Rapid response vertical profiling instrumentation was used to document spatial variability and patterns in a small urban lake, Onondaga Lake, associated with multiple drivers. Paired profiles of temperature, specific conductance (SC), turbidity (Tn), fluorometric chlorophyll a (Chlf), and nitrate nitrogen (NO3?) were collected at >30 fixed locations (a “gridding”) weekly, over the spring to fall interval of several years. These gridding data are analyzed (1) to characterize phytoplankton (Chlf) patchiness in the lake's upper waters, (2) to establish the representativeness of a single long‐term site for monitoring lake‐wide conditions, and (3) to resolve spatial patterns of multiple tracers imparted by buoyancy effects of inflows. Multiple buoyancy signatures were resolved, including overflows from less dense inflows, and interflows to metalimnetic depths and underflows to the bottom from the plunging of more dense inputs. Three different metrics had utility as tracers in depicting the buoyancy signatures as follows: (1) SC, for salinity‐enriched tributaries and the more dilute river that receives the lake's outflow, (2) Tn, for the tributaries during runoff events, and (3) NO3?, for the effluent of a domestic waste treatment facility and from the addition of NO3? solution to control methyl mercury. The plunging inflow phenomenon, which frequently prevailed, has important management implications. 相似文献
64.
Jinxue Luo Jinsong Zhang Xiaohui Tan Diane McDougald Guoqiang Zhuang Anthony G.Fane Staffan Kjelleberg Yehuda Cohen Scott A.Rice 《环境科学学报(英文版)》2015,(3):115-123
Biofilm formation, one of the primary causes of biofouling, results in reduced membrane flux or increased transmembrane pressure and thus represents a major impediment to the wider implementation of membrane bioreactor(MBR) technologies for water purification. Most studies have focused on the role of bacteria in membrane fouling as they are the most dominant and best studied organisms present in the MBR. In contrast, there is limited information on the role of the archaeal community in biofilm formation in MBRs. This study investigated the composition of the archaeal community during the process of biofouling in an MBR. The archaeal community was observed to have lower richness and diversity in the biofilm than the sludge during the establishment of biofilms at low transmembrane pressure(TMP). Clustering of the communities based on the Bray–Curtis similarity matrix indicated that a subset of the sludge archaeal community formed the initial biofilms. The archaeal community in the biofilm was mainly composed of Thermoprotei, Thermoplasmata,Thermococci, Methanopyri, Methanomicrobia and Halobacteria. Among them, the Thermoprotei and Thermoplasmata were present at higher relative proportions in the biofilms than they were in the sludge. Additionally, the Thermoprotei, Thermoplasmata and Thermococci were the dominant organisms detected in the initial biofilms at low TMP, while as the TMP increased, the Methanopyri, Methanomicrobia, Aciduliprofundum and Halobacteria were present at higher abundances in the biofilms at high TMP. 相似文献
65.
Robert A. Rose Dirck Byler J. Ron Eastman Erica Fleishman Gary Geller Scott Goetz Liane Guild Healy Hamilton Matt Hansen Rachel Headley Jennifer Hewson Ned Horning Beth A. Kaplin Nadine Laporte Allison Leidner Peter Leimgruber Jeffrey Morisette John Musinsky Lilian Pintea Ana Prados Volker C. Radeloff Mary Rowen Sassan Saatchi Steve Schill Karyn Tabor Woody Turner Anthony Vodacek James Vogelmann Martin Wegmann David Wilkie Cara Wilson 《Conservation biology》2015,29(2):350-359
In an effort to increase conservation effectiveness through the use of Earth observation technologies, a group of remote sensing scientists affiliated with government and academic institutions and conservation organizations identified 10 questions in conservation for which the potential to be answered would be greatly increased by use of remotely sensed data and analyses of those data. Our goals were to increase conservation practitioners’ use of remote sensing to support their work, increase collaboration between the conservation science and remote sensing communities, identify and develop new and innovative uses of remote sensing for advancing conservation science, provide guidance to space agencies on how future satellite missions can support conservation science, and generate support from the public and private sector in the use of remote sensing data to address the 10 conservation questions. We identified a broad initial list of questions on the basis of an email chain‐referral survey. We then used a workshop‐based iterative and collaborative approach to whittle the list down to these final questions (which represent 10 major themes in conservation): How can global Earth observation data be used to model species distributions and abundances? How can remote sensing improve the understanding of animal movements? How can remotely sensed ecosystem variables be used to understand, monitor, and predict ecosystem response and resilience to multiple stressors? How can remote sensing be used to monitor the effects of climate on ecosystems? How can near real‐time ecosystem monitoring catalyze threat reduction, governance and regulation compliance, and resource management decisions? How can remote sensing inform configuration of protected area networks at spatial extents relevant to populations of target species and ecosystem services? How can remote sensing‐derived products be used to value and monitor changes in ecosystem services? How can remote sensing be used to monitor and evaluate the effectiveness of conservation efforts? How does the expansion and intensification of agriculture and aquaculture alter ecosystems and the services they provide? How can remote sensing be used to determine the degree to which ecosystems are being disturbed or degraded and the effects of these changes on species and ecosystem functions? 相似文献
66.
Air pollutants often have adverse effects on human health. This paper investigates and ranks a set of policy and technological interventions intended to reduce such health costs in the high population density areas of South Africa. It initially uses a simple benefit-cost rule, later extended to capture sectoral employment impacts. Although the focus of state air quality legislation is on industrial pollutants, the most efficient interventions were found to be at household level. These included such low-cost interventions as training householders to place kindling above rather than below the coal in a fireplace and insulating roofs. The first non-household policies to emerge involved vehicle fuels and technologies. Most proposed industrial interventions failed a simple cost-benefit test. The paper's policy messages are that interventions should begin with households and that further industry controls are not yet justifiable in their present forms as these relate to the health care costs of such interventions. 相似文献
67.
Using GIS to Generate Spatially Balanced Random Survey Designs for Natural Resource Applications 总被引:2,自引:0,他引:2
Theobald DM Stevens DL White D Urquhart NS Olsen AR Norman JB 《Environmental management》2007,40(1):134-146
Sampling of a population is frequently required to understand trends and patterns in natural resource management because financial
and time constraints preclude a complete census. A rigorous probability-based survey design specifies where to sample so that
inferences from the sample apply to the entire population. Probability survey designs should be used in natural resource and
environmental management situations because they provide the mathematical foundation for statistical inference. Development
of long-term monitoring designs demand survey designs that achieve statistical rigor and are efficient but remain flexible
to inevitable logistical or practical constraints during field data collection. Here we describe an approach to probability-based
survey design, called the Reversed Randomized Quadrant-Recursive Raster, based on the concept of spatially balanced sampling
and implemented in a geographic information system. This provides environmental managers a practical tool to generate flexible
and efficient survey designs for natural resource applications. Factors commonly used to modify sampling intensity, such as
categories, gradients, or accessibility, can be readily incorporated into the spatially balanced sample design. 相似文献
68.
Antonella Battaglini Johan Lilliestam Armin Haas Anthony Patt 《Journal of Cleaner Production》2009,17(10):911-918
If Europe is serious about reaching its target to keep global mean temperature increase below 2 °C, it must strive for a 100% renewable electricity system by 2050. The SuperSmart Grid approach combines what is often perceived as two exclusive alternatives: wide area power generation and decentralised power generation. We argue that by combining these, in fact, complementary measures, it is possible to address the crucial issue of renewable generation—fluctuating supply—in a comprehensive as well as in a technologically and economically viable manner. Thus, the SuperSmart Grid simultaneously can contribute to energy security, climate security, social security, and national security. 相似文献
69.
70.