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排序方式: 共有349条查询结果,搜索用时 46 毫秒
1.
Samson G. Mengistu Heather E. Golden Charles R. Lane Jay R. Christensen Michael L. Wine Ellen D’Amico Amy Prues Scott G. Leibowitz Jana E. Compton Marc H. Weber Ryan A. Hill 《Journal of the American Water Resources Association》2023,59(5):1162-1179
Eutrophication, harmful algal blooms, and human health impacts are critical environmental challenges resulting from excess nitrogen and phosphorus in surface waters. Yet we have limited information regarding how wetland characteristics mediate water quality across watershed scales. We developed a large, novel set of spatial variables characterizing hydrological flowpaths from wetlands to streams, that is, “wetland hydrological transport variables,” to explore how wetlands statistically explain the variability in total nitrogen (TN) and total phosphorus (TP) concentrations across the Upper Mississippi River Basin (UMRB) in the United States. We found that wetland flowpath variables improved landscape-to-aquatic nutrient multilinear regression models (from R2 = 0.89 to 0.91 for TN; R2 = 0.53 to 0.84 for TP) and provided insights into potential processes governing how wetlands influence watershed-scale TN and TP concentrations. Specifically, flowpath variables describing flow-attenuating environments, for example, subsurface transport compared to overland flowpaths, were related to lower TN and TP concentrations. Frequent hydrological connections from wetlands to streams were also linked to low TP concentrations, which likely suggests a nutrient source limitation in some areas of the UMRB. Consideration of wetland flowpaths could inform management and conservation activities designed to reduce nutrient export to downstream waters. 相似文献
2.
Peggy S. M. Hill 《Die Naturwissenschaften》2009,96(12):1355-1371
Animal communication is a dynamic field that promotes cross-disciplinary study of the complex mechanisms of sending and receiving
signals, the neurobiology of signal detection and processing, and the behaviors of animals creating and responding to encoded
messages. Alongside visual signals, songs, or pheromones exists another major communication channel that has been rather neglected
until recent decades: substrate-borne vibration. Vibrations carried in the substrate are considered to provide a very old
and apparently ubiquitous communication channel that is used alone or in combination with other information channels in multimodal
signaling. The substrate could be ‘the ground’, or a plant leaf or stem, or the surface of water, or a spider’s web, or a
honeybee’s honeycomb. Animals moving on these substrates typically create incidental vibrations that can alert others to their
presence. They also may use behaviors to create vibrational waves that are employed in the contexts of mate location and identification,
courtship and mating, maternal care and sibling interactions, predation, predator avoidance, foraging, and general recruitment
of family members to work. In fact, animals use substrate-borne vibrations to signal in the same contexts that they use vision,
hearing, touch, taste, or smell. Study of vibrational communication across animal taxa provides more than just a more complete
story. Communication through substrate-borne vibration has its own constraints and opportunities not found in other signaling
modalities. Here, I review the state of our understanding of information acquisition via substrate-borne vibrations with special
attention to the most recent literature. 相似文献
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Norman S. Allen Robert McIntyre Julie Maltby Kerrod Claire Hill Michele Edge 《Journal of Polymers and the Environment》2018,26(11):4243-4257
Surface treated macro and nanoparticle TiO2 samples have been prepared, characterised and their efficiency as UV blockers evaluated in clear coatings and paints. The particle size of the ‘base’ TiO2 has been optimised to block UV radiation and the surface treatment developed to deactivate the photocatalytic activity of the surface of the TiO2 particles. The resultant UV blockers have been evaluated in both solvent and water-based clear coatings. Nanoparticle TiO2 has been prepared from ‘seed’ and the particle size was controlled by calcination. It was found that the choice of particle size is a compromise between UVA absorption, UVB absorption, visible transmission and photoactivity. It has been demonstrated that TiO2 with a crystallite size of 25 nm yields a product with the optimum properties. A range of dispersants was successfully used to disperse and mill the TiO2. Both organic and inorganic dispersants were used; 2-amino-2-methyl-1-propanol and 1-amino-2-propanol (MIPA) and P2O5 and Na2SiO3 respectively. The surface of the nano-TiO2 was coated with mixed oxides of silicon, aluminium, zirconium and phosphorous. Addition of the resultant coated nano-rutiles to an Isocyanate Acrylic clear coating prolonged the lifetime of that coating compared to the blank. Generally, a surface treatment based on SiO2, Al2O3 and P2O5 was more successful than one based on ZrO2, Al2O3 and P2O5. Higher addition levels of the surface treatment were beneficial for protecting the polymeric coating. The UV blocker products were also evaluated in a water-based acrylic, first a water-based dispersion of the UV blocker was prepared before addition to the acrylic. The dispersions and resultant acrylic thin films were evaluated using UV/Vis spectroscopy and durability assessed. The ratio of absorbance at 300:500 nm for the water-based dispersion was shown to be a good predictor of both the transparency of the resultant acrylic thin film and the durability of that film, in terms of weight loss. Macro grade titanium dioxide pigments were also prepared and coated with treatments of silica, alumina and siloxane and their photo-stabilising activity in alkyd paint film assessed and found to be directly related to the electron–hole pair mobility and trapping as determined by micro-wave spectroscopy. 相似文献
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6.
The ecosystem services (ES) concept is being increasingly incorporated into environmental policy formulation and management approaches. The Corporate Ecosystem Services Review (ESR) is a framework used to assess the dependence and impact that a business has on ES. The success of the corporate experience of ES assessment provides an opportunity for adaption for local authority decision making. In this paper, the ESR tool was adapted to the South African setting at a local government level, and tested at two sites in the Msunduzi Municipality, KwaZulu-Natal. In testing the tool and gathering feedback from key stakeholders, it was found that there are both opportunities and challenges to this approach. Overall, however, it provides an opportunity for the systematic inclusion of ES assessment into existing regulatory frameworks for land-use planning and Integrated Environmental Management, whether in a strategic application, at a broader spatial (municipal) scale or in a specific locale within the municipality. 相似文献
7.
Cane rats (Thryonomyidae) are represented today by two species inhabiting sub-Saharan Africa. Their fossil record is predominately African, but includes several Miocene species from Arabia and continental Asia that represent dispersal events from Africa. For example, Paraulacodus indicus, known from the Miocene of Pakistan, is closely related to living Thryonomys. Here we describe a new thryonomyid, Protohummus dango, gen. et sp. nov., from the late Miocene Baynunah Formation of the United Arab Emirates. The new thryonomyid is less derived than “Thryonomys” asakomae from the latest Miocene of Ethiopia and clarifies the origin of crown Thryonomys and the evolutionary transition from Paraulacodus. A phylogenetic analysis shows Protohummus dango to be morphologically intermediate between Paraulacodus spp. and extinct and living Thryonomys spp. The morphological grade and phylogenetic position of Protohummus dango further supports previous biochronological estimates of the age of the Baynunah Formation (ca. 6–8 Ma). 相似文献
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9.
Robert H. Hill Jr. Donald G. Patterson Donna L. Orti James S. Holler Larry L. Needham Sandra L. Sirmans 《Journal of environmental science and health. Part. B》2013,48(1):19-33
Abstract Soil samples obtained from the former polybrominated biphenyls (PBB) manufacturing site in Michigan were analyzed by gas chromatography and gas chromatography with mass spectrometric detection. The results indicate significant degradation of the PBB residue in the soil sample. The soil sample with the highest concentration of PBB has the greatest degree of degradation. Principal degradation products include 2,3’,4,4’,5‐pentabromo‐biphenyl, 2,2’,4,4’,5‐pencabromobiphenyl and two unidentified tetrabromobiphenyls. The degradation pattern observed supports a photochemical decomposition mechanism. These degraded residues may be more toxic than the original Firemaster residues. The implications of the results are discussed. 相似文献
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