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31.
Andrew J. Poole Russell E. Lyons Jeffrey S. Church 《Journal of Polymers and the Environment》2011,19(4):995-1004
Feather keratin has been widely studied for use as a bio-based material. In this paper, we dissolve feather keratin using
industrial sodium sulfide to investigate the yield, dissolved keratin characteristics, and properties of regenerated products
to assess the potential of using sodium sulfide as a means of converting waste feathers into a bio-polymer. Optimal conditions
appeared to require short incubation times in order to give maximum strength in the regenerated product. This limits the yield
to approximately 55%. Air-dried films and acid-precipitated samples are all readily re-crosslinked, suggesting the re-crosslinking
process is robust. Minimizing exposure to the highly alkaline conditions appears favorable to final product strength through
minimizing alkaline chain damage. The β-sheet structure of the parent keratin is largely maintained. The regenerated keratin
was shown to have potentially attractive physical properties for use as a bio-polymer. 相似文献
32.
Soil erosion is a serious problem in areas with expanding construction, agricultural production, and improper storm water
management. It is important to understand the major processes affecting sediment delivery to surficial water bodies in order
to tailor effective mitigation and outreach activities. This study analyzes how naturally occurring and anthropogenic influences,
such as urbanization and soil disturbance on steep slopes, are reflected in the amount of soil erosion and sediment delivery
within sub-watershed-sized areas. In this study, two sub-watersheds of the Rappahannock River, Horsepen Run and Little Falls
Run, were analyzed using the Revised Universal Soil Loss Equation (RUSLE) and a sediment delivery ratio (SDR) to estimate
annual sediment flux rates. The RUSLE/SDR analyses for Horsepen Run and Little Falls Run predicted 298 Mg/y and 234 Mg/y,
respectively, but nearly identical per-unit-area sediment flux rates of 0.15 Mg/ha/y and 0.18 Mg/ha/y. Suspended sediment
sampling indicated greater amounts of sediment in Little Falls Run, which is most likely due to anthropogenic influences.
Field analyses also suggest that all-terrain vehicle crossings represent the majority of sediment flux derived from forested
areas of Horsepen Run. The combined RUSLE/SDR and field sampling data indicate that small-scale anthropogenic disturbances
(ATV trails and construction sites) play a major role in overall sediment flux rates for both basins and that these sites
must be properly accounted for when evaluating sediment flux rates at a sub-watershed scale. 相似文献
33.
M. R. Church 《Environmental monitoring and assessment》1999,55(1):1-5
The Bear Brook Watershed Manipulation in Maine is a paired watershed experiment. Monitoring of the paired catchments (East Bear Brook — reference; West Bear Brook — experimental) began in early 1987. Chemical manipulation of West Bear Brook catchment began in November 1989. Process studies on the watershed, outflow observation and monitoring, and modeling simulations of predicted versus observed response, are yielding a wealth of information about the behavior of the paired catchments and their responses to the deposition of acidifying substances. Results from the studies are providing important information relevant to national policies on emissions controls. 相似文献
34.
Downs PW Singer MS Orr BK Diggory ZE Church TC Stella JC 《Environmental management》2011,48(4):847-864
The goal of restoring ecological integrity in rivers is frequently accompanied by an assumption that a comparative reference
reach can be identified to represent minimally impaired conditions. However, in many regulated rivers, no credible historical,
morphological or process-based reference reach exists. Resilient restoration designs should instead be framed around naturalization,
using multiple analytical references derived from empirically-calibrated field- and model-based techniques to develop an integrated
ecological reference condition. This requires baseline data which are rarely collected despite increasing evidence for systematic
deficiencies in restoration practice. We illustrate the utility of baseline data collection in restoration planning for the
highly fragmented and regulated lower Merced River, California, USA. The restoration design was developed using various baseline
data surveys, monitoring, and modeling within an adaptive management framework. Baseline data assisted in transforming conceptual
models of ecosystem function into specific restoration challenges, defining analytical references of the expected relationships
among ecological parameters required for restoration, and specifying performance criteria for post-project monitoring and
evaluation. In this way the study is an example of process-based morphological restoration designed to prompt recovery of
ecosystem processes and resilience. For the Merced River, we illustrate that project-specific baseline data collection is
a necessary precursor in developing performance-based restoration designs and addressing scale-related uncertainties, such
as whether periodic gravel augmentation will sustain bed recovery and whether piecemeal efforts will improve ecological integrity.
Given the numerous impediments to full, historical, restoration in many river systems, it seems apparent that projects of
naturalization are a critical step in reducing the deleterious impacts of fragmented rivers worldwide. 相似文献
35.
Sarah P. Church Lindsey B. Payne Sara Peel Linda S. Prokopy 《Journal of Environmental Planning and Management》2019,62(2):306-326
Survey results of citizen science water data collection volunteers are presented, indicating personal benefits (e.g., being in nature, helping local water quality), and suggesting potential long-term benefits of improved watershed health (e.g., behavior change). These results can inform citizen science program development and contribute to watershed planners’ understanding of the broad benefits of such programs. We suggest that respondents’ positive feelings toward the watershed's major river and desire to learn about science and nature are place-specific elements that watershed and citizen science program managers could utilize in program development. Moreover, we explore the potential of social diffusion and behavior change and suggest the need for further research in these areas. We conclude that citizen science has potential not just as a means to collect large amounts of data (cheaply), but as a means to engage citizens to make environmentally friendly decisions. 相似文献
36.
37.
Hugo A. Loaiciga Richard L. Church 《Journal of the American Water Resources Association》1990,26(4):645-656
ABSTRACT: The minimization of the sum of absolute deviations and the minimization of the absolute maximum deviation (mini-max) were transformed into equivalent linear programs for the estimation of parameters in a transient and linear hydrologic system. It is demonstrated that these two methods yield viable parameter estimates that are globally optimal and reproduce properly the timing and magnitude of hydrologic events and associated variables such as total runoff. The two linear estimation methods compared favorably with the popular least-squares nonlinear estimation method. The generality of the theoretical developments shows that linear program equivalents are adequate competitors of nonlinear methods of hydrologic estimation and parameter calibration. 相似文献
38.
Lara Gotha Vagisha Pruthi Nimrah Abbasi Abhaya V. Kulkarni Paige Church James M. Drake Jose C.A. Carvalho Yenge Diambomba Varsha Thakur Greg Ryan Tim Van Mieghem 《黑龙江环境通报》2020,40(12):1499-1507
Worldwide, about 150 000 infants are born with spina bifida yearly, making this condition one of the most common fetal central nervous system anomalies compatible with life. Over the last decade, major changes have been introduced in the prenatal diagnosis and management of spina bifida. In this review, we provide a brief summary of the current management of fetal spina bifida and present essential information that should be provided to expecting parents when their fetus has been diagnosed with spina bifida. This information is focused around common parental questions, as encountered in our typical clinical practice, to facilitate knowledge translation. 相似文献
39.
Barry P Rochelle Donald L. Stevens M. Robbins. Church 《Journal of the American Water Resources Association》1989,25(3):491-498
ABSTRACT: The U.S. Environmental Protection Agency (EPA) in cooperation with the U.S. Geological Survey (USGS) conducted an analysis to quantify the uncertainty associated with interpolating runoff to specific sites using a runoff contour map. We interpolated runoff to 93 gaged watersheds from a runoff contour map using (1) hand interpolation to the watershed outlet, (2) a computer interpolation to the watershed outlet, and (3) hand interpolation to the watershed centroid. We compared the interpolated values to the actual gaged values and found that there was a bias in the average interpolated value for runoff estimated at basin outlets, with interpolated values being less than the actual. We found no significant difference between the hand interpolation method and the computer interpolation method except that the computer method tended to have higher variability due to factors inherent to the software used. There were no strong spatial correlations or regional patterns in the runoff interpolations, which indicates that there are no regional biases introduced in the development of the contour map. We determined that we could estimate runoff, on the average, within approximately 8.9 cm (3.5 in; 15 percent) of the measured value using the three methods. The results of this work indicate that runoff contour maps can he used in regional studies to estimate runoff to ungaged systems with quantifiable uncertainty. 相似文献
40.
Church CD Kleinman PJ Bryant RB Saporito LS Allen AL 《Journal of environmental quality》2010,39(6):2080-2088
Little is known about the fate of arsenic (As) in land-applied litter from chickens that have been fed roxarsone, an organic feed additive containing As. This study seeks to elucidate the transfer of As in runoff from ditch-drained soils of the poultry-producing region of the Delmarva Peninsula by tracking As and phosphorus (P) export from seven drainage ditches over two water-years (1 July 2005 to 30 June 2007). Annual losses of As from ditches ranged from 0.004 to 0.071 kg ha(-1) while P losses ranged from 0.33 to 18.56 kg ha(-1), with the largest loads associated with a litter storage shed that served as a point source. Event-based As and P losses in ditch flow fluctuated by a factor of 162 and 1882, respectively. The two elements were correlated in flow from the ditch draining a litter storage shed (r = 0.99), and in sediment extracts in soils near the litter shed (r = 0.73), pointing to similar behavior under point source conditions. Indeed, As and P exhibited similar behavior within storms for all ditches, characterized by relatively high initial concentrations subject to rapid concentration declines before peak flow, consistent with dilution of a finite source. However, As and P concentrations varied significantly between ditches and showed considerable temporal variability within ditches, with no clear seasonal trends or associations with current management strategies. The results suggest that similar management strategies might be effective for As and P point sources, but that field management practices geared toward controlling nonpoint source P losses may not readily transfer to the control of As losses. 相似文献