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61.
Burger J Gochfeld M Jeitner C Gray M Shukla T Shukla S Burke S 《Environmental monitoring and assessment》2007,128(1-3):311-321
Kelp may be useful as a bioindicator because they are primary producers that are eaten by higher trophic level organisms,
including people and livestock. Often when kelp or other algae species are used as bioindicators, the whole organism is homogenized.
However, some kelp can be over 25 m long from their holdfast to the tip of the blade, making it important to understand how
contaminant levels vary throughout the plant. We compared the levels of arsenic, cadmium, chromium, lead, manganese, mercury
and selenium in five different parts of the kelp Alaria nana to examine the variability of metal distribution. To be useful as a bioindicator, it is critical to know whether levels are
constant throughout the kelp, or which part is the highest accumulator. Kelp were collected on Adak Island in the Aleutian
Chain of Alaska from the Adak Harbor and Clam Cove, which opens onto the Bering Sea. In addition to determining if the levels
differ in different parts of the kelp, we wanted to determine whether there were locational or size-related differences. Regression
models indicated that between 14% and 43% of the variation in the levels of arsenic, cadmium, chromium, manganese, mercury,
and selenium was explained by total length, part of the plant, and location (but not for lead). The main contributors to variability
were length (for arsenic and selenium), location (mercury), and part of the plant (for arsenic, cadmium, chromium and manganese).
The higher levels of selenium occurred at Clam Cove, while mercury was higher at the harbor. Where there was a significant
difference among parts, the holdfast had the highest levels, although the differences were not great. These data indicate
that consistency should be applied in selecting the part of kelp (and the length) to be used as a bioindicator. While any
part of Alaria could be collected for some metals, for arsenic, cadmium, chromium, and manganese a conversion should be made among parts.
In the Aleutians the holdfast can be perennial while the blade, whipped to pieces by winter wave action, is regrown each year.
Thus the holdfast may be used for longer-term exposure for arsenic, cadmium, chromium and manganese, while the blade can be
used for short-term exposure for all metals. Cadmium, lead and selenium were at levels that suggest that predators, including
people, may be at risk from consuming Alaria. More attention should be devoted to heavy metal levels in kelp and other algae from Adak, particularly where they may play
a role in a subsistence diets. 相似文献
62.
David R. Smith Brian R. Gray Teresa J. Newton Doug Nichols 《Environmental monitoring and assessment》2010,170(1-4):499-507
Adaptive sampling designs are recommended where, as is typical with freshwater mussels, the outcome of interest is rare and clustered. However, the performance of adaptive designs has not been investigated when outcomes are not only rare and clustered but also imperfectly detected. We address this combination of challenges using data simulated to mimic properties of freshwater mussels from a reach of the upper Mississippi River. Simulations were conducted under a range of sample sizes and detection probabilities. Under perfect detection, efficiency of the adaptive sampling design increased relative to the conventional design as sample size increased and as density decreased. Also, the probability of sampling occupied habitat was four times higher for adaptive than conventional sampling of the lowest density population examined. However, imperfect detection resulted in substantial biases in sample means and variances under both adaptive sampling and conventional designs. The efficiency of adaptive sampling declined with decreasing detectability. Also, the probability of encountering an occupied unit during adaptive sampling, relative to conventional sampling declined with decreasing detectability. Thus, the potential gains in the application of adaptive sampling to rare and clustered populations relative to conventional sampling are reduced when detection is imperfect. The results highlight the need to increase or estimate detection to improve performance of conventional and adaptive sampling designs. 相似文献
63.
Sas-Nowosielska A Galimska-Stypa R Kucharski R Zielonka U Małkowski E Gray L 《Environmental monitoring and assessment》2008,137(1-3):101-109
Phytoremediation, an approach that uses plants to remediate contaminated soil through degradation, stabilization or accumulation,
may provide an efficient solution to some mercury contamination problems. This paper presents growth chamber experiments that
tested the ability of plant species to stabilize mercury in soil. Several indigenous herbaceous species and Salix viminalis were grown in soil collected from a mercury-contaminated site in southern Poland. The uptake and distribution of mercury
by these plants were investigated, and the growth and vitality of the plants through a part of one vegetative cycle were assessed.
The highest concentrations of mercury were found at the roots, but translocation to the aerial part also occurred. Most of
the plant species tested displayed good growth on mercury contaminated soil and sustained a rich microbial population in the
rhizosphere. The microbial populations of root-free soil and rhizosphere soil from all species were also examined. An inverse
correlation between the number of sulfur amino acid decomposing bacteria and root mercury content was observed. These results
indicate the potential for using some species of plants to treat mercury contaminated soil through stabilization rather than
extraction. The present investigation proposes a practical cost-effective temporary solution for phytostabilization of soil
with moderate mercury contamination as well as the basis for plant selection. 相似文献
64.
Potential Economic Benefits of Adapting Agricultural Production Systems to Future Climate Change 总被引:2,自引:0,他引:2
Tony Prato Qiu Zeyuan Gregory Pederson Dan Fagre Lindsey E. Bengtson Jimmy R. Williams 《Environmental management》2010,45(3):577-589
Potential economic impacts of future climate change on crop enterprise net returns and annual net farm income (NFI) are evaluated
for small and large representative farms in Flathead Valley in Northwest Montana. Crop enterprise net returns and NFI in an
historical climate period (1960–2005) and future climate period (2006–2050) are compared when agricultural production systems
(APSs) are adapted to future climate change. Climate conditions in the future climate period are based on the A1B, B1, and
A2 CO2 emission scenarios from the Intergovernmental Panel on Climate Change Fourth Assessment Report. Steps in the evaluation include:
(1) specifying crop enterprises and APSs (i.e., combinations of crop enterprises) in consultation with locals producers; (2)
simulating crop yields for two soils, crop prices, crop enterprises costs, and NFIs for APSs; (3) determining the dominant
APS in the historical and future climate periods in terms of NFI; and (4) determining whether NFI for the dominant APS in
the historical climate period is superior to NFI for the dominant APS in the future climate period. Crop yields are simulated
using the Environmental/Policy Integrated Climate (EPIC) model and dominance comparisons for NFI are based on the stochastic
efficiency with respect to a function (SERF) criterion. Probability distributions that best fit the EPIC-simulated crop yields
are used to simulate 100 values for crop yields for the two soils in the historical and future climate periods. Best-fitting
probability distributions for historical inflation-adjusted crop prices and specified triangular probability distributions
for crop enterprise costs are used to simulate 100 values for crop prices and crop enterprise costs. Averaged over all crop
enterprises, farm sizes, and soil types, simulated net return per ha averaged over all crop enterprises decreased 24% and
simulated mean NFI for APSs decreased 57% between the historical and future climate periods. Although adapting APSs to future
climate change is advantageous (i.e., NFI with adaptation is superior to NFI without adaptation based on SERF), in six of
the nine cases in which adaptation is advantageous, NFI with adaptation in the future climate period is inferior to NFI in
the historical climate period. Therefore, adaptation of APSs to future climate change in Flathead Valley is insufficient to
offset the adverse impacts on NFI of such change. 相似文献
65.
Seth Payton Greg Lindsey Jeff Wilson John R. Ottensmann Joyce Man 《Journal of Environmental Planning and Management》2008,51(6):717-736
This paper measures the benefits of the urban forest by examining its effect on housing prices. A Geographic Information System is used to develop a measure of the urban forest, the Normalised Difference Vegetation Index, from satellite imagery and to construct other variables from a variety of sources. Spatial hedonic housing price models for the Indianapolis/Marion County area are estimated. The models indicate that greener vegetation around a property has a positive, significant effect on housing price, holding everything else constant. This effect is dominated by measures at the neighborhood level. These findings indicate that property owners value the urban forest, at least in part, by the premium they pay to live in neighborhoods with greener, denser vegetation. These findings also indicate that public action to maintain and enhance the urban forest may be warranted. Planners and urban foresters can use these findings to inform public and policy debates over urban forestry programs and proposals. 相似文献
66.
Amelia Haviland Author Vitae Author Vitae Wayne Gray Author Vitae Author Vitae John Mendeloff Author Vitae 《Journal of Safety Research》2010,41(4):339-345
Objective
OSHA's enforcement program is one of the major public efforts to protect American workers. We examine both the scope of injury prevention that inspections can contribute and the types of standards that contribute the most.Methods
We linked Pennsylvania Department of Labor and Industry files for lost-time injuries and employment to calculate injury rates for 1998-2005 for all single-establishment manufacturing firms. We linked these to OSHA inspection records.Results
Inspections with penalties did affect injury types unrelated to standards as well as those related. We also found again that citations for violations of the standard requiring personal protective equipment had the largest impact on preventing injuries.Impact on Industry
Programs requiring protective equipment use deserve added attention from consultants and inspectors. In addition, some inspections spur managers to undertake safety measures that go beyond compliance with standards. 相似文献67.
68.
Ecologists commonly use grouped or clustered count data to estimate temporal trends in counts, abundance indices, or abundance. For example, the U.S. Breeding Bird Survey data represent multiple counts of birds from within each of multiple, spatially defined routes. Despite a reliance on grouped counts, analytical methods for prospectively estimating precision of trend estimates or statistical power to detect trends that explicitly acknowledge the characteristics of grouped count data are undescribed. These characteristics include the fact that the sampling variance is an increasing function of the mean, and that sampling and group-level variance estimates are generally estimated on different scales (the sampling and log scales, respectively). We address these issues for repeated sampling of a single population using an analytical approach that has the flavor of a generalized linear mixed model, specifically that of a negative binomial-distributed count variable with random group effects. The count mean, including grand intercept, trend, and random group effects, is modeled linearly on the log scale, while sampling variance of the mean is estimated on the log scale via the delta method. Results compared favorably with those derived using Monte Carlo simulations. For example, at trend = 5% per temporal unit, differences in standard errors and in power were modest relative to those estimated by simulation (< or = /11/% and < or = /16/%, respectively), with relative differences among power estimates decreasing to < or = /7/% when power estimated by simulations was > or = 0.50. Similar findings were obtained using data from nine surveys of fingernail clams in the Mississippi River. The proposed method is suggested (1) where simulations are not practical and relative precision or power is desired, or (2) when multiple precision or power calculations are required and where the accuracy of a fraction of those calculations will be confirmed using simulations. 相似文献
69.
70.