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101.
102.
This paper summarizes research evaluating nitrate levels in shallow groundwater of upstate New York, USA. Water from abandoned dug wells in six different land-use categories was analyzed for nitrate. Findings indicate that regardless of overlying land-use, shallow groundwater is susceptible to high levels of nitrate. Over 60 percent of the water samples tested, including at least one sample from each land-use category, had nitrate levels in excess of the United States drinking water standard of 10 mg 1–1. Due to the potential threat of elevated nitrate levels, efforts should be made to eliminate abandoned dug wells in shallow groundwater as a source of water supply.Glenn Harris is with the Environmental Studies Programme of St Lawrence University in Canton, New York. Brian Henry is with the Department of Entomology at the University of Georgia in Athens, Georgia. Jeffrey Deyette is with the joint International Relations and Resource and Environmental Management Programme at Boston University in Boston, Massachusetts. This research was performed as a Community Service Project sponsored by the Mergardt Fund while Mr Henry and Mr Deyette were students under the supervision of Dr Harris at St Lawrence University. 相似文献
103.
Probability plots of trace element concentrations may be used to partition, or segregate, sample data into its constituent
populations. Two populations are typically present in data from sites requiring remedial action, one representing clean, uncontaminated
soil or sediment (background) and the other representing contaminated ground. The use of such plots in the analysis and evaluation
of environmental data permits a statistical characterization of the background populations, from which defensible cleanup
criteria may be developed. These criteria will be environmentally conservative, yet will minimize the amount of soil removed
in a remedial action. An example is given from a successful cleanup of a surface impoundment. 相似文献
104.
Marie Boehm Henry Janzen Bob MacGregor Murray Fulton 《Mitigation and Adaptation Strategies for Global Change》2004,9(4):503-504
Subject Index
Subject Index 相似文献105.
106.
107.
Mycoplasma pneumoniae is a pathogenic eubacterium lacking a cell wall. Three decades ago, a "rod", an intracellular cytoskeletal structure, was discovered that was assumed to define and stabilize the elongated cell shape. Later, by treatment with detergent, a "Triton shell" (i.e. a fraction of detergent-insoluble cell material) could be obtained, believed to contain additional cytoskeletal elements. Now, by application of a modified Triton X-100 treatment, we are able to demonstrate that M. pneumoniae possesses a cytoskeleton consisting of a blade-like rod and a peripheral lining located close to the inner face of the cytoplasmic membrane, exhibiting features of a highly regular network. Attached "stalks" may support the cytoplasmic membrane. The rod was connected to the cell periphery by "spokes" and showed a defined ultrastructure. Its proximal end was found to be attached to a wheel-like complex. Fibrils extended from the proximal end of the rod into the cytoplasm. 相似文献
108.
Venema Henry D. Schiller Eric J. Bass Brad 《Mitigation and Adaptation Strategies for Global Change》1996,1(2):139-165
The ongoing drought in the Sahel region of West Africa highlights the vulnerability of food-producing systems to climate change
and variability. Adaptation to climate should therefore increase the sustainability of agriculture under a long-term drought.
Progress towards sustainability and adaptation in the the Senegal River Basin is hampered by an existing set of social and
ecological relationships that define the control over the means of production and how people interact with their environment.
These relationships are sensitive to the technological inputs and the administration of food production, or the factor bias
in the different policy alternatives for rural development. One option is based on state-controlled, irrigated plantations
to provide rice (Oryza) for the capital, Dakar. This policy emphasizes a top-down management approach, mechanized agriculture and a reliance on
external inputs which strengthens the relationships introduced during the colonial period.
A time series decomposition of the annual flow in the Senegal River at Bakel in Senegal suggests that water resources availability
has been substantially curtailed since 1960, and a review of the water resources budget or availability in the basin suggests
that this policy's food production system is not sustainable under the current climate of the basin. Under these conditions,
this program is exacerbating existing problems of landscape degradation and desertification, which increases rural poverty.
A natural resource management policy offers two adaptation strategies that favour decentralized management and a reduction
of external inputs. The first alternative, “Les Perimetres Irrigués”, emphasizes village-scale irrigation, low water consumption
cereal crops and traditional socio-political structures. The second alternative emphasizes farm-level irrigation and agro-forestry
projects to redress the primary effects of desertification. 相似文献
109.
Spencer E. Fire Deborah Fauquier Leanne J. Flewelling Michael Henry Jerome Naar Richard Pierce Randall S. Wells 《Marine Biology》2007,152(4):827-834
Bottlenose dolphins (Tursiops truncatus) face a variety of threats, including risk of exposure to brevetoxins produced by blooms of the harmful alga Karenia brevis. This study investigated brevetoxin exposure in a population of dolphins inhabiting Sarasota Bay, Florida, USA (27°N, 82°W),
utilizing tissues from dolphins recovered between 1994 and 2003. Brevetoxin levels detected by ELISA in tissues, gastric samples
and excreta from dolphin carcasses (n = 19) associated with K. brevis blooms were compared with with levels in carcasses (n = 16) associated with background K. brevis conditions. In the K. brevis-exposed set, 84% of dolphin carcasses recovered during K. brevis blooms had detectable brevetoxin levels, with values ranging between 7 and 2,896 ng PbTx-3 eq g−1. Over 50% of dolphin carcasses recovered during non-bloom conditions also tested positive by ELISA for brevetoxins, with
concentrations ranging from 6 to 44 ng PbTx-3 eq g−1. Control samples from the east coast of Florida were negative by the ELISA. Results from this study establish baseline brevetoxin
body burdens in a dolphin population frequently exposed to K. brevis blooms, and data indicate that dolphin carcasses not associated with large-scale mortality events can contain levels of brevetoxins
comparable to carcasses stranding during such events. 相似文献
110.
Henry RC 《Journal of the Air & Waste Management Association (1995)》2005,55(11):1760-1766
Regional haze regulations require progress toward reducing atmospheric haze as measured by particle scattering coefficient of visible light. From a practical perspective, this raises the following question: Given a decrease in extinction, what is the probability that people will notice an improvement in visibility? This paper proposes a quantitative definition of the probability of a perceptible increase in visibility given a decrease in light extinction and a general method to estimate this probability from perception measurements made in the field under realistic conditions. Using data from a recent study of visibility perception by 8 observers, it is estimated that a 2-4 deciview change gives a 67% maximum probability of detecting the improvement. Stated another way, the odds of seeing a difference are at most 2:1 for a change of 2-4 deciviews. A 90% probability requires a change of at least 3.5-7.0 deciviews. The limitations and possible bias in the results of this study are discussed. These results may have a major effect on the cost-benefit analysis of regulatory actions to improve visibility. 相似文献