6,611 research outputs found

    PROFILE OF ANIMATION INTERACTIVE MEDIA ON BIOGEOCHEMICAL CYCLE MATTER FOR SENIOR HIGH SCHOOL

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    Animation interactive media can explain an abstract concept to more real. This research aimed to produce biogeochemical cycle animation interactive media which is fesiable theoretically. Feasibility theoretically got from a results of media validity by biology lecturers and teachers. The validation media aspects are graph quality, animation quality, program quality, physical quality, present quality, matter quality, and illustration quality. This development research used ASSURE model which consist of six phases. The validation media result percentage was 85,26% and got very feasible category that implementation feasible in the learning. Keywords: animation interactive media, biogeochemical cycle, feasibility theoreticall

    Anthropogenic perturbations to the biogeochemical cycle of silicon

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    Globally, human activities are altering nutrient biogeochemical cycles. The impact of humans on silicon (Si) cycles remains largely unexplored. Understanding the cycle of Si is important because weathering of siliceous rocks is a substantial sink of atmospheric carbon. Additionally, Si is required by diatoms. Diatoms form the base of important socioeconomic food webs, responsible for ~50% of oceanic net primary production, and deliver atmospheric carbon to ocean sediments as part of the ocean’s biological pump. My dissertation aims to assess the role of anthropogenic activities in altering Si cycling across the land-ocean continuum. Chapter 2 focuses on how assimilation of biogenic silica (BSi) by trees may be impacted by projected changes in climate. Using samples collected during a multi-year, snow removal experiment, I show that increased frequency and duration of soil freezing in winter significantly decreased (-28%) BSi in sugar maple (Acer saccharum) fine roots compared to control plots. Importantly, I observed that fine roots are a previously undescribed pool of BSi within sugar maples, accounting for 29% of total sugar maple BSi while only 4% of sugar maple biomass. Chapter 3 examines the origin and fate of Si within wastewater for the City of Boston. I determined the total dissolved silica (DSi) load in wastewater influent (69,500 kmol DSi year-1), then parsed the total DSi flux between Si contributions of sewage (49%), groundwater infiltration (39%), and surface runoff inflow (12%). In Chapter 4, I study the DSi load carried by treated effluent. I determined that effluent load (67,800 kmol DSi year-1) is not statistically different from influent load, indicating that wastewater treatment does not remove DSi. In Chapter 5 I demonstrate how humans impact concentrations of DSi in urban groundwater. Groundwater DSi increases with human presence and urban areas have significantly higher concentrations of DSi compared to groundwater conditions along the Massachusetts coast. I demonstrate that historic variables defining fill techniques, fill material, and pre-fill land-use out preform geologic variables in predicting urban groundwater DSi concentrations. This dissertation highlights human alterations to biological assimilation, fate, and effects of Si in sewage, and centuries-long subsurface Si impacts that perturb the distribution and availability of a nutrient intimately tied to water quality and climate

    STIMULASI AKTIVITAS KOGNITIF MELALUI MODELING EXAMPLE SERTA HUBUNGANNYA DENGAN BEBAN KOGNITIF DAN KEMAMPUAN PENALARAN SISWA SMA PADA PEMBELAJARAN SIKLUS BIOGEOKIMIA

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    Siswa masih banyak yang mengalami kegagalan dalam menguraikan siklus biogeokimia, terutama siklus karbon dan nitrogen. Ketika memperoleh informasi mengenai siklus biogeokimia, terjadi aktivitas kognitif dalam diri siswa. Kompleksitas siklus biogeokimia mengakibatkan kognitif siswa terbebani oleh tugas memproses informasi yang ada dalam siklus biogeokimia. Salah satu pendekatan yang dapat diterapkan pada pembelajaran siklus biogeokimia yaitu modeling example. Penelitian ini bertujuan untuk stimulasi aktivitas kognitif melalui modeling example serta hubungannya dengan beban kognitif dan kemampuan penalaran siswa pada pembelajaran siklus biogeokimia. Metode penelitian yang digunakan yaitu quasi experiment dengan desain penelitian non equivalent control group post-test only design. Subjek penelitian berjumlah 60 siswa dari dua kelas X MIPA tahun ajaran 2019/2020 pada pembelajaran siklus biogeokimia (siklus air, siklus nitrogen, dan siklus karbon). Instrumen yang digunakan dalam penelitian ini yaitu lembar observasi aktivitas kognitif, task complexity worksheet, angket subjective rating scale dan soal pilihan ganda beralasan (two-tier test). Hasil penelitian menunjukkan bahwa aktivitas kognitif siswa yang belajar dengan modeling example termasuk dalam kategori tinggi. Selain itu, intrinsic cognitive load (ICL) dan extraneous cognitive load (ECL) siswa termasuk dalam kategori rendah. Kemampuan penalaran siswa termasuk dalam kategori sangat tinggi.Terdapat hubungan antara aktivitas kognitif dengan intrinsic cognitive load (ICL). Hubungan antara aktivitas kognitif dengan kemampuan penalaran siswa yang belajar dengan modeling example sifatnya bukan korelasional, tetapi menunjukkan hubungan sebab akibat. Terdapat hubungan yang signifikan antara kemampuan menerima dan memproses informasi (MMI) dengan kemampuan penalaran siswa. There are still many students who experience failures in deciphering the biogeochemical cycle, especially the carbon and nitrogen cycle. When obtaining information about the biogeochemical cycle, cognitive activity occurs in students. The complexity of the biogeochemical cycle results in students' cognitive load by the task of processing information in the biogeochemical cycle. One approach that can be applied to biogeochemical cycle learning is modeling examples. This study aims to stimulate cognitive activity through modeling examples and its relationship with the cognitive load and reasoning abilities of students in learning biogeochemical cycles. The research method used was a quasi-experiment with a non-equivalent control group post-test only design. The research subjects were 60 students from two classes X MIPA in the 2019/2020 academic year on learning the biogeochemical cycle (water cycle, nitrogen cycle, and carbon cycle). The instruments used in this study were cognitive activity observation sheets, task complexity worksheets, a subjective rating scale questionnaire, and two-tier reasoned questions. The results showed that the cognitive activity of students who studied with modeling example was in the high category. Also, students' intrinsic cognitive load (ICL) and extraneous cognitive load (ECL) were included in the low category. Students' reasoning abilities are in the very high category. There is a relationship between cognitive activity and intrinsic cognitive load (ICL). The relationship between cognitive activities and the reasoning abilities of students who learn using modeling examples is not correlational, but shows a causal relationship. There is a significant relationship between the ability to receive and process information (MMI) and students' reasoning abilities

    The Terrestrial Biogeochemical Cycle of barium: A proposed study to examine barium flux in Mojave Desert dust

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    Barium is a relatively abundant element in the crustal environments, Ba quantities can range from anywhere between 200ppm to 900ppm. Most common forms of Ba-minerals found in the environment are barite (BaSO4), witherite (BaCO3) and hollandite (Ba2Mn8O16). Ba is a useful element; it is used in various industries as a component in drilling fluids, in medical research and in manufacturing of various substances such as glass, ceramics, printing paper etc. However high quantity of Ba can be potentially toxic for the human body and can impair plant growth. It is therefore, important to review the terrestrial biogeochemical cycle of Ba, which is less studied and less understood than the oceanic biogeochemical cycle of Ba. Additionally, terrestrial systems face a diverse climate and are not as stable as the oceanic systems. Due to this the terrestrial biogeochemical cycle of barium is continuously changing and is more dynamic than the oceanic cycle. By studying one part of the cycle, i.e. the interaction of Ba in the atmosphere with the geosphere in the Mojave desert, NV, I propose a study to test the hypothesis that occurrence of, Ba-mineral, barite, in desert soils is mainly driven by dust flux. The proposal includes methodology for dust collection, sample analysis using XRF, XRD and SEM.EDS techniques and potential budget and timeline. Evidence supporting this claim would suggest that dust transports such minerals, affects the soil chemistry of desert soils and the interaction of various terrestrial systems

    Extreme-halophiles: their role in the arsenic biogeochemical cycle

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    Biofilms, mats and microbialites dwell under extreme environmental conditions (high salinity, extreme aridity, pH and arsenic concentration) in the Argentinean Puna and the Atacama Desert. Microbial communities inhabiting those ecosystems are poorly known. Arsenic metabolism is proposed to be an ancient mechanism in microbial life. Besides, some bacteria and archaea are not only able to use detoxification processes to grow under high arsenic concentration, but also, some of them are able to exploit arsenic as a bioenergetic substrate in either anaerobic arsenate respiration or chemolithotrophic growth on arsenite. Only four aioAB coding for arsenite oxidase and two arrA coding for arsenate reductase sequences from haloarchaea were previously deposited in the NCBI Database, but have not been reported in the literature. The arrA arsenate reductases are reliable indicators of anaerobic As (V) respiration and catalyze the electron transfer to the As (V) terminal acceptor in dissimilatory arsenatereducing prokaryotes (DARPs). In this work, we are presenting our first steps in the study of the arsenic biogeochemical cycle in these ecosystems. Thus, the aim of this study was to isolate and to study the arsenic metabolism genes of the isolated extreme halophile microorganisms as well as to test the growth in minimal medium using different carbon sources. Mats and microbialites samples were taken from the water’s edge of Laguna Tebenquiche, Laguna Brava (Salar de Atacama, Chile) during December 2012 and from gaylusite crystals (Laguna Diamante) in August 2014. Samples were enriched and plated in WS medium supplemented with arsenic (AsIII 0.5mM and AsV 20mM). Arsenite oxidase (aioB) and Arsenate reductase (arrA) primers specific for haloarchaea were designed using PrimerProspector software. Selected primers were aioB-1190F (5’-GCTCMTSACCGGCAGCGTCG-3’), aioB-1507R (5’-YGATCTCGTCGATGTCGGCG-3’), arrA-417F (5’CCCGAGTTCGAGCCSATCTC-3’) and arrA-614R (5’GCRCAGATCGMGCTGTGGGA-3’). In order to identify the isolates we used Archaea-specific primers for 16S rDNA gene amplification: 344F (5´- ACG GGG YGC AGC AGG CGC GA-3´) and 915R (5´- GTG CTC CCC CGC CAA TTC CT -3´). Fragments of 577 bp, 317pb and 197pb were obtained from 16S rDNA, aioB and arrA genes respectively. Universal primers 27F and 1492R were used to amplify 16S rDNA in bacterial isolates. 25 isolates belonging to Archaea and Bacteria Domain were obtained; they are related to the Phylum Euryarchaeota, Firmicutes and Proteobacteria. AioB and arrA genes were found in most of the isolates and DNA from the samples (mats, microbialites and biofilm). The best carbon source tested was pyruvate and acetate, being pyruvate better in all cases. Promising results were obtained in the search of organisms able to use arsenic in their bioenergetic metabolism. More studies are underway to try to better understand these very interesting systems.Fil: Rasuk, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Ordoñez, Omar Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Soria, Mariana Noelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaXI Congreso Argentino de Microbiología GeneralCordobaArgentinaSociedad Argentina de Microbiología Genera

    Biogeochemical modeling at mass extinction boundaries

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    The causes of major mass extinctions is a subject of considerable interest to those concerned with the history and evolution of life on earth. The primary objectives of the proposed plan of research are: (1) to develop quantitative time-dependent biogeochemical cycle models, coupled with an ocean atmosphere in order to improve the understanding of global scale physical, chemical, and biological processes that control the distribution of elements important for life at times of mass extinctions; and (2) to develop a comprehensive data base of the best available geochemical, isotopic, and other relevant geologic data from sections across mass extinction boundaries. These data will be used to constrain and test the biogeochemical model. These modeling experiments should prove useful in: (1) determining the possible cause(s) of the environmental changes seen at bio-event boundaries; (2) identifying and quantifying little-known feedbacks among the oceans, atmosphere, and biosphere; and (3) providing additional insights into the possible responses of the earth system to perturbations of various timescales. One of the best known mass extinction events marks the Cretaceous/Tertiary (K/T) boundary (66 Myr ago). Data from the K/T boundary are used here to constrain a newly developed time-dependent biogeochemical cycle model that is designed to study transient behavior of the earth system. Model results predict significant fluctuations in ocean alkalinity, atmospheric CO2, and global temperatures caused by extinction of calcareous plankton and reduction in the sedimentation rates of pelagic carbonates and organic carbon. Oxygen-isotome and other paleoclimatic data from K/T time provide some evidence that such climatic fluctuations may have occurred, but stabilizing feedbacks may have acted to reduce the ocean alkalinity and carbon dioxide fluctuations

    A Cenozoic-style scenario for the end-Ordovician glaciation

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    The end-Ordovician was an enigmatic interval in the Phanerozoic, known for massive glaciation potentially at elevated CO2 levels, biogeochemical cycle disruptions recorded as large isotope anomalies and a devastating extinction event. Ice-sheet volumes claimed to be twice those of the Last Glacial Maximum paradoxically coincided with oceans as warm as today. Here we argue that some of these remarkable claims arise from undersampling of incomplete geological sections that led to apparent temporal correlations within the relatively coarse resolution capability of Palaeozoic biochronostratigraphy. We examine exceptionally complete sedimentary records from two, low and high, palaeolatitude settings. Their correlation framework reveals a Cenozoic-style scenario including three main glacial cycles and higher-order phenomena. This necessitates revision of mechanisms for the end-Ordovician events, as the first extinction is tied to an early phase of melting, not to initial cooling, and the largest δ13C excursion occurs during final deglaciation, not at the glacial apex

    Dimethyl sulfide production: what is the contribution of the coccolithophores?

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