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11.
J. Van Sickle P J. Wigington M. K. Church 《Journal of the American Water Resources Association》1997,33(2):359-366
ABSTRACT: Programs of monthly or annual stream water sampling will rarely observe the episodic extremes of acidification chemistry that occur during brief, unpredictable runoff events. When viewed in the context of data from several streams, however, baseflow measurements of variables such as acid neutralizing capacity, pH and NO3· are likely to be highly correlated with the episodic extremes of those variables from the same stream and runoff season. We illustrate these correlations for a water chemistry record, nearly two years in length, obtained from intensive sampling of 13 small Northeastern U.S. streams studied during USEPA's Episodic Response Project. For these streams, simple regression models estimate episodic extremes of acid neutralizing capacity, pH, NO3·, Ca2+, SO42?, and total dissolved Al with good relative accuracy from statistics of monthly or annual index samples. Model performances remain generally stable when episodic extremes in the second year of sampling are predicted from first-year models. Monthly or annual sampling designs, in conjunction with simple empirical models calibrated and maintained through intensive sampling every few years, may estimate episodic extremes of acidification chemistry with economy and reasonable accuracy. Such designs would facilitate sampling a large number of streams, thereby yielding estimates of the prevalence of episodic acidification at regional scales. 相似文献
12.
Longevity can buffer plant and animal populations against changing climatic variability 总被引:3,自引:0,他引:3
Morris WF Pfister CA Tuljapurkar S Haridas CV Boggs CL Boyce MS Bruna EM Church DR Coulson T Doak DF Forsyth S Gaillard JM Horvitz CC Kalisz S Kendall BE Knight TM Lee CT Menges ES 《Ecology》2008,89(1):19-25
Both means and year-to-year variances of climate variables such as temperature and precipitation are predicted to change. However, the potential impact of changing climatic variability on the fate of populations has been largely unexamined. We analyzed multiyear demographic data for 36 plant and animal species with a broad range of life histories and types of environment to ask how sensitive their long-term stochastic population growth rates are likely to be to changes in the means and standard deviations of vital rates (survival, reproduction, growth) in response to changing climate. We quantified responsiveness using elasticities of the long-term population growth rate predicted by stochastic projection matrix models. Short-lived species (insects and annual plants and algae) are predicted to be more strongly (and negatively) affected by increasing vital rate variability relative to longer-lived species (perennial plants, birds, ungulates). Taxonomic affiliation has little power to explain sensitivity to increasing variability once longevity has been taken into account. Our results highlight the potential vulnerability of short-lived species to an increasingly variable climate, but also suggest that problems associated with short-lived undesirable species (agricultural pests, disease vectors, invasive weedy plants) may be exacerbated in regions where climate variability decreases. 相似文献
13.
Daniela Diaz Jared Church Mikaeel Young Keug Tae Kim Jungsu Park Yun Bin Hwang Swadeshmukul Santr Woo Hyoung Lee 《环境科学学报(英文版)》2019,31(8):213-224
Intensification of pollution loading worldwide has promoted an escalation of different types of disease-causing microorganisms, such as harmful algal blooms(HABs), instigating detrimental impacts on the quality of receiving surface waters. Formation of unwanted disinfection by-products(DBPs) resulting from conventional disinfection technologies reveals the need for the development of new sustainable alternatives. Quaternary Ammonium Compounds(QACs) are cationic surfactants widely known for their effective biocidal properties at the ppm level. In this study, a novel silica-based antimicrobial nanofilm was developed using a composite of silica-modified QAC(Fixed-Quat) and applied to a fiberglass mesh as an active surface via sol–gel technique. The synthesized Fixed-Quat nanocoating was found to be effective against E. coli with an inactivation rate of 1.3 × 10~(-3) log reduction/cm min. The Fixed-Quat coated fiberglass mesh also demonstrated successful control of Microcystis aeruginosa with more than 99% inactivation after 10 hr of exposure.The developed antimicrobial mesh was also evaluated with wild-type microalgal species collected in a water body experiencing HABs, obtaining a 97% removal efficiency. Overall,the silica-functionalized Fixed-Quat nanocoating showed promising antimicrobial properties for water disinfection and HABs control, while decreasing concerns related to DBPs formation and the possible release of toxic nanomaterials into the environment. 相似文献
14.
15.
Understanding global sea levels: past, present and future 总被引:4,自引:0,他引:4
John A. Church Neil J. White Thorkild Aarup W. Stanley Wilson Philip L. Woodworth Catia M. Domingues John R. Hunter Kurt Lambeck 《Sustainability Science》2008,3(1):9-22
The coastal zone has changed profoundly during the 20th century and, as a result, society is becoming increasingly vulnerable
to the impact of sea-level rise and variability. This demands improved understanding to facilitate appropriate planning to
minimise potential losses. With this in mind, the World Climate Research Programme organised a workshop (held in June 2006)
to document current understanding and to identify research and observations required to reduce current uncertainties associated
with sea-level rise and variability. While sea levels have varied by over 120 m during glacial/interglacial cycles, there
has been little net rise over the past several millennia until the 19th century and early 20th century, when geological and
tide-gauge data indicate an increase in the rate of sea-level rise. Recent satellite-altimeter data and tide-gauge data have
indicated that sea levels are now rising at over 3 mm year−1. The major contributions to 20th and 21st century sea-level rise are thought to be a result of ocean thermal expansion and
the melting of glaciers and ice caps. Ice sheets are thought to have been a minor contributor to 20th century sea-level rise,
but are potentially the largest contributor in the longer term. Sea levels are currently rising at the upper limit of the
projections of the Third Assessment Report of the Intergovernmental Panel on Climate Change (TAR IPCC), and there is increasing
concern of potentially large ice-sheet contributions during the 21st century and beyond, particularly if greenhouse gas emissions
continue unabated. A suite of ongoing satellite and in situ observational activities need to be sustained and new activities
supported. To the extent that we are able to sustain these observations, research programmes utilising the resulting data
should be able to significantly improve our understanding and narrow projections of future sea-level rise and variability. 相似文献
16.
Deposition of sea salts is commonly elevated along the coast relative to inland areas, yet little is known about the effects on terrestrial ecosystem biogeochemistry. We examined the influence of NaCl concentrations on N, C, and P leaching from a coastal Oregon forest Andisol in two laboratory studies: a rapid batch extraction (approximately 1 d) and a month-long incubation using microlysimeters. In the rapid extractions, salt additions immediately mobilized significant amounts of ammonium and phosphate but not nitrate. In the month-long incubations, salt additions at concentrations in the range of coastal precipitation increased nitrate leaching from the microcosms by nearly 50% and reduced the mobility of dissolved organic carbon. Our findings suggest that coupled abiotic-biotic effects increase nitrate mobility in these soils: exchange of sodium for ammonium, then net nitrification. Changes in sea salt deposition to land and the interactions with coastal soils could alter the delivery of N and C to sensitive coastal waters. 相似文献
17.
Marwan A. Hassan Michael Church Thomas E. Lisle Francesco Brardinoni Lee Benda Gordon E. Grant 《Journal of the American Water Resources Association》2005,41(4):853-876
This paper reviews sediment transport and channel morphology in small, forested streams in the Pacific Northwest region of North America to assess current knowledge of channel stability and morphology relevant to riparian management practices around small streams. Small channels are defined as ones in which morphology and hydraulics may be significantly influenced by individual clasts or wood materials in the channel. Such channels are headwater channels in close proximity to sediment sources, so they reflect a mix of hillslope and channel processes. Sediment inputs are derived directly from adjacent hillslopes and from the channel banks. Morphologically significant sediments move mainly as bed load, mainly at low intensity, and there is no standard method for measurement. The larger clastic and woody elements in the channel form persistent structures that trap significant volumes of sediment, reducing sediment transport in the short term and substantially increasing channel stability. The presence of such structures makes modeling of sediment flux in these channels — a potential substitute for measurement — difficult. Channel morphology is discussed, with some emphasis on wood related features. The problem of classifying small channels is reviewed, and it is recognized that useful classifications are purpose oriented. Reach scale and channel unit scale morphologies are categorized. A “disturbance cascade” is introduced to focus attention on sediment transfers through the slope channel system and to identify management practices that affect sediment dynamics and consequent channel morphology. Gaps in knowledge, errors, and uncertainties have been identified for future research. 相似文献
18.
Gary D. Bishop M. Robbins Church Christopher Daly 《Journal of the American Water Resources Association》1998,34(1):159-166
ABSTRACT: We evaluated maps of runoff created by means of two automated procedures. We implemented each procedure using precipitation estimates of both 5-km and 10-km resolution from PRISM (Parameter-elevation Regressions on Independent Slopes Model). Our goal was to determine if using the 5-km PRISM estimates would improve map accuracy. Visual inspection showed good general agreement among our runoff maps, as well as between our maps and one produced using a manual method. A quantitative uncertainty analysis comparing runoff interpolated from our maps with gage data that had been withheld showed slightly smaller actual and percentage interpolation errors for the 5-km PRISM-based maps. Our analyses suggest a modest region-wide improvement in runoff map accuracy with the use of PRISM-based precipitation estimates of 5-km (compared to 10-km) resolution. 相似文献
19.
Serum concentrations of perfluorooctanesulfonate and other fluorochemicals in an elderly population from Seattle, Washington 总被引:14,自引:0,他引:14
Olsen GW Church TR Larson EB van Belle G Lundberg JK Hansen KJ Burris JM Mandel JH Zobel LR 《Chemosphere》2004,54(11):1599-1611
Perfluorooctanesulfonyl fluoride (POSF, C8F17SO2F) related-materials have been used as surfactants, paper and packaging treatments, and surface (e.g., carpet, textile, upholstery) protectants. A metabolite, perfluorooctanesulfonate (PFOS, C8F17SO3−), has been identified in the serum and liver of non-occupationally exposed humans and wildlife. Because of its persistence, an important question was whether elderly humans might have higher PFOS concentrations. From a prospective study designed to examine cognitive function in the Seattle (WA) metropolitan area, blood samples were collected from 238 dementia-free subjects (ages 65–96). High-pressure liquid chromatography-electrospray tandem mass spectrometry determined seven fluorochemicals: PFOS; N-ethyl perfluorooctanesulfonamidoacetate; N-methyl perfluorooctanesulfonamidoacetate; perfluorooctanesulfonamidoacetate; perfluorooctanesulfonamide; perfluorooctanoate; and perfluorohexanesulfonate. Serum PFOS concentrations ranged from less than the lower limit of quantitation (3.4 ppb) to 175.0 ppb (geometric mean 31.0 ppb; 95% CI 28.8–33.4). An estimate of the 95% tolerance limit was 84.1 ppb (upper 95% confidence limit 104.0 ppb). Serum PFOS concentrations were slightly lower among the most elderly. There were no significant differences by sex or years residence in Seattle. The distributions of the other fluorochemicals were approximately an order of magnitude lower. Similar to other reported findings of younger adults, the geometric mean serum PFOS concentration in non-occupational adult populations likely approximates 30–40 ppb with 95% of the population’s serum PFOS concentrations below 100 ppb. 相似文献
20.
The SITES reserve selection system: A critical review 总被引:1,自引:0,他引:1
Douglas?T.?FischerEmail author Richard?L.?Church 《Environmental Modeling and Assessment》2005,10(3):215-228
Numerous models have been put forth to help with the growing demand for the establishment of biodiversity reserves. One site
selection model that has been used in several recent studies is SITES [S.J. Andelman, I. Ball, F.W. Davis and D.M. Stoms,
SITES V 1.0: an analytical toolbox for designing ecoregional conservation portfolios, Unpublished manual prepared for the
nature conservancy, 1999, 1–43. (available at )]. SITES includes two heuristic solvers: based on Greedy and Simulated Annealing. We discuss the formulation of the SITES
model, present a new formulation for that problem, and solve a number of test problems optimally using off-the-shelf software.
We compared our optimal results with the SITES Simulated Annealing heuristic and found that SITES frequently returns significantly
suboptimal solutions. Our results add further support to the argument, started by Underhill [L.G. Underhill, Optimal and suboptimal
reserve selection algorithms, Biol. Conserv. 70 (1994) 85–87], continuing through Rodrigues and Gaston [A.S.L. Rodrigues and
K.J. Gaston, Optimization in reserve selection procedures – why not?, Biol. Conserv. 107 (2002) 123–129], for greater integration
of optimal methods in the reserve design/selection literature. 相似文献