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排序方式: 共有293条查询结果,搜索用时 31 毫秒
1.
Adam C. Landon Maarten H. Jacobs Craig A. Miller Jerry J. Vaske Brent D. Williams 《社会与自然资源》2020,33(5):574-593
AbstractIncreasing wolf populations are a concern for wildlife managers in the Midwestern U.S. Understanding the psychological mechanisms that contribute to public perceptions of risk will enable development of strategies that seek to mitigate these risks, and suggest where outreach efforts may facilitate acceptance of wolves. We examined the psychological factors that influence Illinois residents’ perceived risks from wolves. We hypothesized that individuals’ perceived risks from wolves were a function of their attitudes toward wolves, negative affect toward wolves, and basic beliefs about wildlife. Data were obtained from a survey of the Illinois public (n?=?784). Negative affect and attitudes toward wolves were direct predictors of perceived risks. Basic beliefs predicted attitudes and negative affect toward wolves. Negative affect predicted attitudes. Basic beliefs had direct and indirect effects on perceived risks. 相似文献
2.
Recent studies have suggested that poikilothermic animals, such as fish, may represent a previously overlooked source of the faecal indicator bacteria (FIB) used for the assessment of water quality. However, quantitative studies of FIB in poikilotherms are scarce. We investigated the presence of FIB in the faeces of five freshwater fish species. E. coli and enterococci were detected in 71 and 76% of faecal samples, respectively. Concentrations were highly variable, with maximum concentrations (2.1?×?104 E. coli and 1.3?×?106 enterococci per gram of faecal material) up to four orders of magnitude higher than present in the water column. FIB were not detected in faecal samples from marine fish. Our findings suggest that FIB ingested from the environment may be capable of replication within the fish gut, making fish a potential source and transport mechanism for FIB in New Zealand freshwaters. This may have implications for water quality monitoring. 相似文献
3.
4.
Natural Hazards - Urban flooding is a reoccurring disaster, and its frequency and intensity are likely to increase in the future due to the increasing frequency of storm events. Up-to-date... 相似文献
5.
Natural Hazards - How have property buyouts and disaster recovery assistance programs been implemented in Canadian communities? This paper compares contrasting policies and programs in two Canadian... 相似文献
6.
Troy P. Sampere Thomas S. Bianchi Mead A. Allison Brent A. McKee 《Estuarine, Coastal and Shelf Science》2011
The primary focus of this paper is to better understand carbon burial on the Louisiana continental margin using spatial scales that covered various shelf depositional areas far-field and near-field (sediment and organic carbon inputs relative to river mouth proximity) and covering a variety of sedimentation rates. Box-cores samples were collected in July 2003; cores were collected along two depositional transects extending westward and southward from the Southwest Pass (SW Pass). A key difference between the two transects sampled in this study was the greater occurrence of mobile muds derived from spillover from shallower regions along the westward 50 m isobaths. The dominant mechanism for mixing in the surface active zone (SAZ) on the inner Louisiana shelf was due to physical, not biological, forces. Burial efficiencies for organic carbon (57.2–91.5%) and total nitrogen (44.2–86.9%) ranged widely across all shelf stations. Lower burial efficiencies for bulk organic carbon, total nitrogen, and pigment biomarkers were associated with mobile muds west of Southwest Pass. Chlorophyll a concentrations were significantly higher than pheopigments at depth at the Mississippi River and Southwest Pass stations, making up 40.4 and 77.4% of total pigment concentrations in the (SAZ) and 46.2 and 63.2% in the accumulation zone (AZ), respectively. These results are in agreement with earlier plant pigment studies which showed that a large fraction of the phytodetritus delivered to the inner shelf was derived from coastal and river diatoms. The amount of lignin preserved with depth decreased with increasing residence time in the SAZ and diagenetic zone (DZ) along the canyon transect but not along the western transect. Trends for lignin concentration followed previously identified surface sediment trends indicating overall lower burial of refractory terrestrial material at depth with greater distance offshore. 相似文献
7.
The Permo‐Carboniferous to Eocene Sverdrup Basin in Canada's Arctic Archipelago is strongly influenced by evaporite diapirism. However, salt structures within the basin have not been extensively investigated recently due to their remote location. This study includes the interpretation of legacy seismic reflection and borehole data to characterize the geometry of selected evaporite domes, and 1D backstripping of wells to investigate tectonic and sedimentary influences on diapirism. Extensional rift‐structures appear to have played a significant role in the formation of evaporite domes by triggering and directing salt movement. Diapirism was initiated by at least the Middle Triassic and continued to develop during the Mesozoic. Differential loading of salt on opposing east–west dome margins led to their present day asymmetric geometries. Diapir growth rates in the Mesozoic were closely linked to the rate of sedimentation and influenced by regional tectonism. 相似文献
8.
Gwen C. Woods Brent G. Pautler Melissa J. Lafrenière 《Geochimica et cosmochimica acta》2011,75(22):7226-7241
Arctic landscapes are believed to be highly sensitive to climate change and accelerated disturbance of permafrost is expected to significantly impact the rate of carbon cycling. While half the global soil organic matter (SOM) is estimated to reside in Arctic soils, projected warmer temperatures and permafrost disturbance will release much of this SOM into waterways in the form of dissolved organic matter (DOM). The spring thaw and subsequent flushing of soils releases the highest contributions of DOM annually but has historically been undersampled due to the difficulties of sampling during this period. In this study, passive samplers were placed throughout paired High Arctic watersheds during the duration of the 2008 spring flush in Nunavut, Canada. The watersheds are very similar with the exception of widespread active layer detachments (ALDs) that occurred within one of the catchments during a period of elevated temperatures in the summer of 2007. DOM samples were analyzed for structural and spectral characteristics via nuclear magnetic resonance (NMR) and fluorescence spectroscopy as well as vulnerability to degradation with simulated solar exposure. Lignin-derived phenols were further assessed utilizing copper(II) oxide (CuO) oxidation and gas chromatography/mass spectrometry (GC/MS). The samples were found to have very low dissolved lignin phenol content (∼0.07% of DOC) and appear to originate from primarily non-woody angiosperm vegetation. The acid/aldehyde ratios for dissolved vanillyl phenols were found to be high (up to 3.6), indicating the presence of highly oxidized lignin. Differences between DOM released from the ALD vs. the undisturbed watershed suggest that these shallow detachment slides have significantly impacted the quality of Arctic DOM. Although material released from the disturbed catchment was found to be highly oxidized, DOM in the lake into which this catchment drained had chemical characteristics indicating high contributions from microbial and/or primary productivity. The resulting pool of dissolved carbon within the lake appears to be more biologically- and photochemically-labile than material from the undisturbed system. These disturbances may have implications for projected climate warming; sustained elevated temperatures would likely perpetuate widespread ALDs and further affect carbon cycling in this environment. 相似文献
9.
Francesca A. McInerney Brent R. Helliker Katherine H. Freeman 《Geochimica et cosmochimica acta》2011,75(2):541-554
We analyzed hydrogen isotope ratios of high-molecular weight n-alkanes (δDl) and oxygen isotope ratios of α-cellulose (δ18OC) for C3 and C4 grasses grown in the field and in controlled-environment growth chambers. The relatively firm understanding of 18O-enrichment in leaf water and α-cellulose was used to elucidate fractionation patterns of δDl signatures. In the different relative humidity environments of the growth chambers, we observed clear and predictable effects of leaf-water enrichment on δ18OC values. Using a Craig-Gordon model, we demonstrate that leaf water in the growth chamber grasses should have experienced significant D-enriched due to transpiration. Nonetheless, we found no effect of transpirational D-enrichment on the δDl values. In field samples, we saw clear evidence of enrichment (correlating with relative humidity of the field sites) in both δ18OC and δDl. These seemingly contrasting results could be explained if leaf waxes are synthesized in an environment that is isotopically similar to water entering plant roots due to either temporal or spatial isolation from evaporatively enriched leaf waters. For grasses in the controlled environment, there was no enrichment of source water, whereas enrichment of grass source water via evaporation from soils and/or stems was likely for grass samples grown in the field.Based on these results, evaporation from soils and/or stems appears to affect δDl, but transpiration from leaves does not. Further evidence for this conclusion is found in modeling expected net evapotranspirational enrichment. A Craig-Gordon model applied to each of the field sites yields leaf water oxygen isotope ratios that can be used to accurately predict the observed δ18OC values. In contrast, the calculated leaf water hydrogen isotope ratios are more enriched than what is required to predict observed δDl values. These calculations lend support to the conclusion that while δ18OC reflects both soil evaporation and transpiration, δDl appears to only record evaporation from soils and/or stems. Therefore, the δD of n-alkanes can likely be used to reconstruct the δD of water entering a leaf, supporting the soil-enrichment model of Smith and Freeman (2006). In both the field and controlled studies, we found significant photosynthetic pathway effects on n-alkane δD suggesting that biochemical pathways or plant phylogeny have a greater effect on leaf wax δD than leaf-water enrichment in grasses. 相似文献
10.
Stephen Walsh Kevin Anderson John Hathaway Brent Pulsipher 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(6):805-814
We present a statistical methodology which aims to monitor and assess the progress of unexploded ordnance remediation. We
explicitly quantify the probability that each buried sensor-identified anomaly is not a target of interest conditional on
the information gleaned from anomalies which have been dug and identified. We provide a measure of confidence that the anomalies
which remain onsite after remediation are not unexploded ordnance—this measure of confidence is gleaned through Monte Carlo
methods. The methodology is iterative in that, at any point in the remediation process, we can assess remediation progress
and compute the probability that no targets of interest remain given the available dig information. 相似文献