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21.
Pilkington MG Caporn SJ Carroll JA Cresswell N Lee JA Ashenden TW Brittain SA Reynolds B Emmett BA 《Environmental pollution (Barking, Essex : 1987)》2005,135(1):29-40
This study was designed to investigate the leaching response of an upland moorland to long-term (10 yr) ammonium nitrate additions of 40, 80 and 120 kg N ha(-1) yr(-1) and to relate this response to other indications of potential system damage, such as acidification and cation displacement. Results showed increases in nitrate leaching only in response to high rates of N input, in excess of 96 and 136 kg total N input ha(-1) yr(-1) for the organic Oh horizon and mineral Eag horizon, respectively. Individual N additions did not alter ammonium leaching from either horizon and ammonium was completely retained by the mineral horizon. Leaching of dissolved organic nitrogen (DON) from the Oh horizon was increased by the addition of 40 kg N ha(-1) yr(-1), but in spite of increases, retention of total dissolved nitrogen reached a maximum of 92% and 95% of 80 kg added N ha(-1) yr(-1) in the Oh and Eag horizons, respectively. Calcium concentrations and calcium/aluminium ratios were decreased in the Eag horizon solution with significant acidification mainly in the Oh horizon leachate. Nitrate leaching is currently regarded as an early indication of N saturation in forest systems. Litter C:N ratios were significantly lowered but values remained above a threshold predicted to increase leaching of N in forests. 相似文献
22.
Carroll WF Berger TC Borrelli FE Garrity PJ Jacobs RA Ledvina J Lewis JW McCreedy RL Smith TP Tuhovak DR Weston AF 《Chemosphere》2001,43(4-7):689-700
This is the consolidated report of emissions of PCDD/F from facilities in the organic chemical manufacturing chain leading to polyvinyl chloride. Data have been gathered from facilities in the US and Canada from a number of manufacturers and at various steps in the manufacturing process. Estimates of US emissions or transfers of PCDD/F were generated on an "Upper Bound" and "Most Likely" basis. The Most Likely estimate of US emissions of PCDD/F to the open environment, that is, air, water and land surface by facilities in this chain, based on evaluation of non-detects at one-half the detection limit is about 12 g I-TEQ per year. On this same basis, an estimated 19 g is disposed of in secure landfills. 相似文献
23.
Centrality metrics evaluate paths between all possible pairwise combinations of sites on a landscape to rank the contribution of each site to facilitating ecological flows across the network of sites. Computational advances now allow application of centrality metrics to landscapes represented as continuous gradients of habitat quality. This avoids the binary classification of landscapes into patch and matrix required by patch-based graph analyses of connectivity. It also avoids the focus on delineating paths between individual pairs of core areas characteristic of most corridor- or linkage-mapping methods of connectivity analysis. Conservation of regional habitat connectivity has the potential to facilitate recovery of the gray wolf (Canis lupus), a species currently recolonizing portions of its historic range in the western United States. We applied 3 contrasting linkage-mapping methods (shortest path, current flow, and minimum-cost-maximum-flow) to spatial data representing wolf habitat to analyze connectivity between wolf populations in central Idaho and Yellowstone National Park (Wyoming). We then applied 3 analogous betweenness centrality metrics to analyze connectivity of wolf habitat throughout the northwestern United States and southwestern Canada to determine where it might be possible to facilitate range expansion and interpopulation dispersal. We developed software to facilitate application of centrality metrics. Shortest-path betweenness centrality identified a minimal network of linkages analogous to those identified by least-cost-path corridor mapping. Current flow and minimum-cost-maximum-flow betweenness centrality identified diffuse networks that included alternative linkages, which will allow greater flexibility in planning. Minimum-cost-maximum-flow betweenness centrality, by integrating both land cost and habitat capacity, allows connectivity to be considered within planning processes that seek to maximize species protection at minimum cost. Centrality analysis is relevant to conservation and landscape genetics at a range of spatial extents, but it may be most broadly applicable within single- and multispecies planning efforts to conserve regional habitat connectivity. 相似文献
24.
Gro Harlaug Olsen Michael L. Carroll Paul E. Renaud William G. AmbroseJr Ragni Olssøn JoLynn Carroll 《Marine Biology》2007,151(6):2167-2176
We assessed the effects of crude oil and drill cuttings on sediment oxygen demand (SOD) of marine benthic communities from
Arctic (Barents Sea) and temperate (Oslofjord) areas of the Norwegian continental shelf. Field-collected cores in both areas
were subjected to three different treatments: two concentrations of hydrocarbon-contaminated sediments, and drill cuttings
(DC). Cores were incubated for 21 days at 5°C (Barents Sea) and at 10°C (Oslofjord) during which SOD was measured five times.
We observed significantly higher SOD in the high oil concentration (HOC) and DC treatments compared to control cores from
the Arctic, but not in the temperate Oslofjord. No difference was observed between the low oil concentration (LOC) and control
at either location. The clear differences in the response of Arctic benthic communities to petroleum compounds compared to
temperate benthic communities is likely related to differences in community structure, sensitivity of individual taxa to petroleum-related
compounds and different contamination history of the two study areas. 相似文献
25.
Evenset A Christensen GN Carroll J Zaborska A Berger U Herzke D Gregor D 《Environmental pollution (Barking, Essex : 1987)》2007,146(1):196-205
Ellasj?en receives contaminants from both atmospheric and biological transport (seabird guano). Historical trends of selected persistent organic pollutants and metals were determined by interpretation of down-core contaminant profiles in conjunction with sediment layer ages, determined by the (210)Pb method. Polychlorinated biphenyls (PCBs) and dichloro-diphenyl-trichloroethane and metabolites (DDTs) increased from about 1930 until 1970 (max. sum PCBs 71.8 ng/g dry weight (dw), max sum DDTs 4.0 ng/g dw), declining afterwards to 46.4 ng/g dw and 1.6 ng/g dw, respectively. Polybrominated diphenylethers (PBDEs) concentrations are increasing in Ellasj?en, reaching 0.73 ng/g dw in 2001. Hexabromocyclododekane (HBCD) was measured only in sediment from 1-2 cm depth (0.43 and 3.88 ng/g dw of alpha- and gamma-HBCD, respectively). Most metals (As, Cd, Co, Ni and Zn) showed a similar pattern as PCBs. No clear trends were observed for Cr, Pb or V. Mercury (Hg) has increased gradually since the beginning of the industrial era. 相似文献
26.
J. C. Coll B. F. Bowden G. V. Meehan G. M. Konig A. R. Carroll D. M. Tapiolas P. M. Aliño A. Heaton R. De Nys P. A. Leone M. Maida T. L. Aceret R. H. Willis R. C. Babcock B. L. Willis Z. Florian M. N. Clayton R. L. Miller 《Marine Biology》1994,118(2):177-182
This paper provides the first evidence for sperm chemotaxis in the Scleractinia. Montipora digitata Dana, 1845 (Scleractinia: Coelenterata) is a hermaphroditic coral which reproduces bi-annually, releasing egg-sperm bundles during the mass spawning at Magnetic Island (19°10S; 146°52E) in late spring-early summer, and autumn each year. The buoyant egg-sperm bundles float to the surface where they break apart, releasing eggs and sperm into the ocean. Fertilisation occurs after 30 min. Unfertilized eggs were collected, washed free of sperm, and freeze-dried. The eggs were extracted with dichloromethane, fractionated by chromatography on silica gel, and the fractions assayed for their ability to attract M. digitata sperm. The active fraction was further fractionated by high-performance liquid chromatography, resulting in the isolation of three highly unsaturated fatty alcohols: (1) dodeca-2,4-diynol; (2) tetradec-13-ene-2,4-diynol; (3) (14Z)-heptadeca-14,16-diene-2,4-diynol. Of these three compounds, only Compound 1 attracted sperm of M. digitata. Synthetic Compound 1, produced from simple precursors by known reactions, possessed sperm-attracting activity comparable to the naturally derived attractant. Preliminary experiments suggest that the natural mixture of Compounds 1, 2 and 3 in the ratio 1:4:9 is more effective in attracting sperm from M. digitata than sperm from other Montipora species. Sperm attractants may act to reduce the incidence of hybridisation between different species of Montipora. 相似文献
27.
This paper examines the underlying assumptions and consequences of applying a steady-state equation to sediment profiles of radioactive tracers in order to deconvolute sedimentation from bioturbation processes modelled as a diffusive type process.Several factors follow immediately from this investigation:
- (i)
- if the observed radioactive concentration increases with depth over any finite depth range then the proposed steady-state, constant flux equation is not applicable. Any increase in radioactive concentration with depth implies a negative mixing coefficient which is a physical impossibility;
- (ii)
- when the radioactive concentration systematically decreases with increasing sedimentary depth then solutions to the steady-state conservation equation exist only when either the constant solid state flux to the sediment surface is small enough so that a positive mixing coefficient results or when the mixing coefficient is small enough so that a positive flux results.
28.
Travis B. Paveglio Pamela J. Jakes Matthew S. Carroll Daniel R. Williams 《Environmental management》2009,43(6):1085-1095
The lack of knowledge regarding social diversity in the Wildland Urban Interface (WUI) or an in-depth understanding of the
ways people living there interact to address common problems is concerning, perhaps even dangerous, given that community action
is necessary for successful wildland fire preparedness and natural resource management activities. In this article, we lay
out the knowledge and preliminary case study evidence needed to begin systematically documenting the differing levels and
types of adaptive capacity WUI communities have for addressing collective problems such as wildland fire hazard. In order
to achieve this end, we draw from two theoretical perspectives encompassing humans' interactions with their environment, including
(1) Kenneth Wilkinson's interactional approach to community, (2) and certain elements of place literature. We also present
case study research on wildfire protection planning in two drastically different California communities to illustrate how
social diversity influences adaptive capacity to deal with hazards such as wildland fire. These perspectives promote an image
of the WUI not as a monolithic entity but a complex mosaic of communities with different needs and existing capacities for
wildland fire and natural resource management. 相似文献
29.
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