10 research outputs found
Sedimentary redox geochemistry of the Lower Triassic Montney Formation, British Columbia
No full textThe end-Permian mass extinction ~252 Mya was the most severe biotic crisis in Earth history, with \u3e90 % of marine species going extinct. It was followed by 5 million years of reduced biodiversity and large perturbations in global biogeochemical cycling. Delayed earth system recovery after the Permian-Triassic mass extinction is often attributed to marine anoxia. However, the extent of marine anoxia and the influence of global versus local drivers remains poorly constrained. To further evaluate the role of redox conditions during the recovery period after the Permian-Triassic mass extinction we conducted geochemical analyses on 395 m of core through the Lower Triassic Montney Formation. Samples were analyzed for pyrite sulfur contents, iron speciation, major and minor elemental compositions, and total organic carbon measurements. These proxies, used as signals of shifting redox conditions, can be used to interpret the depositional environment and correlate to other time-equivalent basins. Additionally, 22 thin sections were prepared to determine mineralogy trends in relation to redox changes. Stratigraphic trends of iron proxies show that the Montney Formation was deposited under persistent anoxic conditions. These geochemical data also suggest that redox conditions shifted towards euxinic conditions at 3 intervals: after the PTB, during the Smithian-Spathian boundary and the at the beginning of Lower Anisian. Occurrences of glauconitic grains near the Permian Triassic boundary and into the Griesbachian also point towards more complex variations in redox conditions associated with the end-Permian mass extinction. The Early Triassic was also a period of recurrent carbon isotope perturbations as observed in Triassic sections across the Tethys ocean. Repeated disturbances to the carbon cycle combined with persistent anoxia and shifts to euxinia ma
Effects of laboratory experiements on the learning of science by visually impared pupils: the case of Magwero Basic and Katete Integrated Schools
No full textThis study investigated effects of laboratory experiments on the learning of
science subjects by visually impaired pupils for grade nine (9) and twelve
(12)pupils in the two selected schools (Magwero school for the Blind and Katete
integrated Boarding school) in Eastern Province of Zambia. Data was analyzed by
describing and explaining results from laboratory experiments and sixty (60)
responses were analyzed using tables, graphs, means and percentages. The study results show that lack of vision, teaching and learning resources, poor or absence of laboratory infrastructures and lack of science trained and specialist teachers contributed to poor performance of the visually impaired students in laboratory experiments in the two (special and integrated) schools. The study revealed that the visually impaired pupils had problems in determining concreteness and unifying experiences of ordinary materials and apparatus used in laboratory experiments. As a result of the above findings the author made these recommendations:
1. The Ministry of Education should increase funding for special education from
ten (10%) percent to forty (40%) percent.
2. The Ministry of Education should renovate and build laboratorie.
3. The Ministry of Education should train non-special education teachers and specialist teachers in braille and science respectively.
4. Teachers of science should modify the existing ordinary materials to suit the visually impaired pupils
Environmental controls on green bands in marine sediments
No full textWidely observed banding in marine sediments is believed to be connected to oxygen-sensitive diagenetic processes in shallow sediments. This study combines a spatial survey of distinctive banding in shallow sediments (<1 m below seafloor) with novel 1 million-year long records of banding occurrence at International Ocean Discovery Program (IODP) Sites U1474 and U1313 to assess the link between sedimentary diagenetic band and bottom water oxygen across the middle to late Pleistocene. The spatial survey of banding in shallow sediments indicates that bands at active redox fronts are connected to high bottom-water oxygen concentrations, while the stratigraphic survey shows numerous instances of the synchronous development of banding in both hemispheres during the glaciations of the Pleistocene in tandem with low bottom-water oxygen events. A review of available evidence suggests that the diagenetic bands form due to rising bottom-water oxygen concentrations, which trap reduced iron sourced from organic matter-enriched deposits from a preceding low-oxygen interval. Connections among Southern Ocean productivity, green-band abundance, Mediterranean sapropel occurrence, and the 400-kyr benthic δ13C cycle point to the possibility of long-term variability in deep-ocean oxygenation across the Pleistocene
ARE ALL SHALES CREATED EQUAL?: A COMPARATIVE, MULTI-PROXY GEOCHEMICAL STUDY OF PALEOZOIC AND MESOZOIC PRODUCING SHALE BASINS IN NORTH AMERICA
No full text
Study protocol: the impact of growth charts and nutritional supplements on child growth in Zambia (ZamCharts): a cluster randomized controlled trial
No full texthttps://www.researchsquare.com/article/rs-2816403/v1First author draf
Smallholder Cassava Planting Material Movement and Grower Behavior in Zambia: Implications for the Management of Cassava Virus Diseases.
No full textCassava (Manihot esculenta) is an important food crop across sub-Saharan Africa, where production is severely inhibited by two viral diseases, cassava mosaic disease (CMD) and cassava brown streak disease (CBSD), both propagated by a whitefly vector and via human-mediated movement of infected cassava stems. There is limited information on growers' behavior related to movement of planting material, as well as growers' perception and awareness of cassava diseases, despite the importance of these factors for disease control. This study surveyed a total of 96 cassava subsistence growers and their fields across five provinces in Zambia between 2015 and 2017 to address these knowledge gaps. CMD symptoms were observed in 81.6% of the fields, with an average incidence of 52% across the infected fields. No CBSD symptoms were observed. Most growers used planting materials from their own (94%) or nearby (<10 km) fields of family and friends, although several large transactions over longer distances (10 to 350 km) occurred with friends (15 transactions), markets (1), middlemen (5), and nongovernmental organizations (6). Information related to cassava diseases and certified clean (disease-free) seed reached only 48% of growers. The most frequent sources of information related to cassava diseases included nearby friends, family, and neighbors, while extension workers were the most highly preferred source of information. These data provide a benchmark on which to plan management approaches to controlling CMD and CBSD, which should include clean propagation material, increasing growers' awareness of the diseases, and increasing information provided to farmers (specifically disease symptom recognition and disease management options).[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY 4.0 International license
The Sedimentary Geochemistry and Paleoenvironments project
No full textAuthors thank the donors of The American Chemical Society Petroleum Research Fund for partial support of SGP website development (61017-ND2). EAS is funded by National Science Foundation grant (NSF) EAR-1922966. BGS authors (JE, PW) publish with permission of the Executive Director of the British Geological Survey, UKRI.Peer reviewe
