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11.
Multiple behavioral and chemical studies indicate that ant nestmate recognition cues are low-volatile substances, in particular hydrocarbons (HCs) located on the cuticular surface. We tested the hypothesis that in the ant Camponotus fellah, nest environment, in particular nest volatile odors, can modulate nestmate-recognition-mediated aggression. Workers were individually confined within their own nest in small cages having either a single mesh (SM = limited physical contact permitted) or a double mesh (DM = exposed to nest volatiles only) screen. Individual workers completely isolated outside their nest (CI) served as control. When reintroduced into a group of 50 nestmates, the CI workers were attacked as alien ants after only 2 weeks of separation, whereas the SM workers were treated as nestmates even after 2 months of separation. Aggression towards DM ants depended on the period of isolation. Only DM workers isolated for over 2 months were aggressed by their nestmates, which did not significantly differ from the CI nestmates. Cuticular HC analyses revealed that the profile of the non-isolated ants (NI) was clearly distinct from that of CI, SM and DM ants. Profile differences matched the aggressive response in the case of CI ants but were uncorrelated in the case of SM or DM ants. This suggests that keeping the ants within the nest environment affected nestmate recognition in additional ways than merely altering their HC profile. Nest environment thus appears to affect label–template mismatch by modulating aggressive behavior, as well as the direction at which cuticular HCs diverged during the separation period. 相似文献
12.
Three-dimensional data interpolation for environmental purpose: lead in contaminated soils in southern Brazil 总被引:1,自引:0,他引:1
Tales Campos Piedade Vander Freitas Melo Luiz Cláudio Paula Souza Jeferson Dieckow 《Environmental monitoring and assessment》2014,186(9):5625-5638
Monitoring of heavy metal contamination plume in soils can be helpful in establishing strategies to minimize its hazardous impacts to the environment. The objective of this study was to apply a new approach of visualization, based on tridimensional (3D) images, of pseudo-total (extracted with concentrated acids) and exchangeable (extracted with 0.5 mol L?1 Ca(NO3)2) lead (Pb) concentrations in soils of a mining and metallurgy area to determine the spatial distribution of this pollutant and to estimate the most contaminated soil volumes. Tridimensional images were obtained after interpolation of Pb concentrations of 171 soil samples (57 points × 3 depths) with regularized spline with tension in a 3D function version. The tridimensional visualization showed great potential of use in environmental studies and allowed to determine the spatial 3D distribution of Pb contamination plume in the area and to establish relationships with soil characteristics, landscape, and pollution sources. The most contaminated soil volumes (10,001 to 52,000 mg Pb kg?1) occurred near the metallurgy factory. The main contamination sources were attributed to atmospheric emissions of particulate Pb through chimneys. The large soil volume estimated to be removed to industrial landfills or co-processing evidenced the difficulties related to this practice as a remediation strategy. 相似文献
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14.
R. W. P. M. Laane J. Van Der Meer A. De Vries A. Van Der Giessen 《Environmental management》1990,14(2):221-227
During the winter period an inverse linear relation is found between the concentration of dissolved nutrients (phosphorus
and nitrogen) and salinity in the Dutch coastal zone. This indicates a conservative behavior of these compounds from the river,
through the estuary to the sea. During summer this relation is much more scattered because of biological processes. The physical
and statistical properties of the relationship between salinity and the concentration of dissolved inorganic phosphorus and
nitrogen are used to calculate when, where, and how many samples have to be taken in order to monitor a reduction of a compound
accurately. It appeared that at any given salinity in the estuary and in the sea, the winter period is the most suitable season
to detect a reduction of a given dissolved compound. The higher the salinity in the estuary, the more samples are required
to prove the reduction significantly. A reduction of only 10% cannot even be demonstrated by field measurements during summer
at salinities above 25. It is concluded that one cruise from the river to the sea, covering the salinities from 0 to 35 during
the winter period, aimed at establishing the relationship between the concentration and salinity by taking samples at a salinity
interval of for instance 1%, is sufficient to monitor a wide-ranging reduction of 10%–50% in both the fresh water and marine
water. This program must be combined with a sampling at a salinity of 0, directed to determine the riverine temporal variability. 相似文献
15.
Landscape Planning for Agricultural Nonpoint Source Pollution Reduction I: A Geographical Allocation Framework 总被引:1,自引:1,他引:0
Agricultural nonpoint source pollution remains a persistent environmental problem, despite the large amount of money that
has been spent on its abatement. At local scales, agricultural best management practices (BMPs) have been shown to be effective
at reducing nutrient and sediment inputs to surface waters. However, these effects have rarely been found to act in concert
to produce measurable, broad-scale improvements in water quality. We investigated potential causes for this failure through
an effort to develop recommendations for the use of riparian buffers in addressing nonpoint source pollution in Wisconsin.
We used frequency distributions of phosphorus pollution at two spatial scales (watershed and field), along with typical stream
phosphorus (P) concentration variability, to simulate benefit/cost curves for four approaches to geographically allocating
conservation effort. The approaches differ in two ways: (1) whether effort is aggregated within certain watersheds or distributed
without regard to watershed boundaries (dispersed), and (2) whether effort is targeted toward the most highly P-polluting
fields or is distributed randomly with regard to field-scale P pollution levels. In realistic implementation scenarios, the
aggregated and targeted approach most efficiently improves water quality. For example, with effort on only 10% of a model
landscape, 26% of the total P load is retained and 25% of watersheds significantly improve. Our results indicate that agricultural
conservation can be more efficient if it accounts for the uneven spatial distribution of potential pollution sources and the
cumulative aspects of environmental benefits. 相似文献
16.
On the relative contributions of wind vs. animals to seed dispersal of four Sierra Nevada pines 总被引:2,自引:0,他引:2
Vander Wall SB 《Ecology》2008,89(7):1837-1849
Selective pressures that influence the form of seed dispersal syndromes are poorly understood. Morphology of plant propagules is often used to infer the means of dispersal, but morphology can be misleading. Several species of pines, for example, have winged seeds adapted for wind dispersal but owe much of their establishment to scatter-hoarding animals. Here the relative importance of wind vs. animal dispersal is assessed for four species of pines of the eastern Sierra Nevada that have winged seeds but differed in seed size: lodgepole pine (Pinus contorta murrayana, 8 mg); ponderosa pine (Pinus ponderosa ponderosa, 56 mg); Jeffrey pine (Pinus jeffreyi, 160 mg); and sugar pine (Pinus lambertiana, 231 mg). Pre-dispersal seed mortality eliminated much of the ponderosa pine seed crop (66%), but had much less effect on Jeffrey pine (32% of seeds destroyed), lodgepole pine (29%), and sugar pine (7%). When cones opened most filled seeds were dispersed by wind. Animals removed > 99% of wind-dispersed Jeffrey and sugar pine seeds from the ground within 60 days, but animals gathered only 93% of lodgepole pine seeds and 38% of ponderosa pine seeds during the same period. Animals gathered and scatter hoarded radioactively labeled ponderosa, Jeffrey, and sugar pine seeds, making a total of 2103 caches over three years of study. Only three lodgepole pine caches were found. Caches typically contained 1-4 seeds buried 5-20 mm deep, depths suitable for seedling emergence. Although Jeffrey and sugar pine seeds are initially wind dispersed, nearly all seedlings arise from animal caches. Lodgepole pine is almost exclusively wind dispersed, with animals acting as seed predators. Animals treated ponderosa pine in an intermediate fashion. Two-phased dispersal of large, winged pine seeds appears adaptive; initial wind dispersal helps to minimize pre-dispersal seed mortality whereas scatter hoarding by animals places seeds in sites with a higher probability of seedling establishment. 相似文献
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18.
Agricultural non–point source (NPS) pollution poses a severe threat to water quality and aquatic ecosystems. In response,
tremendous efforts have been directed toward reducing these pollution inputs by implementing agricultural conservation practices.
Although conservation practices reduce pollution inputs from individual fields, scaling pollution control benefits up to the
watershed level (i.e., improvements in stream water quality) has been a difficult challenge. This difficulty highlights the
need for NPS reduction programs that focus efforts within target watersheds and at specific locations within target watersheds,
with the ultimate goal of improving stream water quality. Fundamental program design features for NPS control programs—i.e.,
number of watersheds in the program, total watershed area, and level of effort expended within watersheds—have not been considered
in any sort of formal analysis. Here, we present an optimization model that explores the programmatic and environmental trade-offs
between these design choices. Across a series of annual program budgets ranging from $2 to $200 million, the optimal number
of watersheds ranged from 3 to 27; optimal watershed area ranged from 29 to 214 km2; and optimal expenditure ranged from $21,000 to $35,000/km2. The optimal program configuration was highly dependent on total program budget. Based on our general findings, we delineated
hydrologically complete and spatially independent watersheds ranging in area from 20 to 100 km2. These watersheds are designed to serve as implementation units for a targeted NPS pollution control program currently being
developed in Wisconsin. 相似文献
19.
20.
Landscape Planning for Agricultural Nonpoint Source Pollution Reduction III: Assessing Phosphorus and Sediment Reduction Potential 总被引:2,自引:0,他引:2
Riparian buffers have the potential to improve stream water quality in agricultural landscapes. This potential may vary in
response to landscape characteristics such as soils, topography, land use, and human activities, including legacies of historical
land management. We built a predictive model to estimate the sediment and phosphorus load reduction that should be achievable
following the implementation of riparian buffers; then we estimated load reduction potential for a set of 1598 watersheds
(average 54 km2) in Wisconsin. Our results indicate that land cover is generally the most important driver of constituent loads in Wisconsin
streams, but its influence varies among pollutants and according to the scale at which it is measured. Physiographic (drainage
density) variation also influenced sediment and phosphorus loads. The effect of historical land use on present-day channel
erosion and variation in soil texture are the most important sources of phosphorus and sediment that riparian buffers cannot
attenuate. However, in most watersheds, a large proportion (approximately 70%) of these pollutants can be eliminated from
streams with buffers. Cumulative frequency distributions of load reduction potential indicate that targeting pollution reduction
in the highest 10% of Wisconsin watersheds would reduce total phosphorus and sediment loads in the entire state by approximately
20%. These results support our approach of geographically targeting nonpoint source pollution reduction at multiple scales,
including the watershed scale. 相似文献