bluuebunny/crossref_metadata_2025_split huggingface dataset:
Factors Influencing the Level of Conversion of Rice Fields into Catfish Farms in Los Amigos, Davao City, Philippines
Authors: Borres Beltran C. , Garillos Emmalinda A. 
Published: November 2016

This descriptive-correlational study is used to determine the relationship between the level of conversion of rice fields into catfish farms and the current status of the factors which are rice farming, catfish farming, government programs in rice production, and environmental conditions. There were 33 respondents considered in this study who were the catfish growers. Data gathered were analyzed using frequency counts and percentages, mean, and Pearson product correlation or Pearson r. The study found out that the level of perception of respondents was high on the current status of catfish farming and environmental conditions. For government programs on rice production, respondents had a moderately high level of perception. There is also a high level of conversion of rice fields into catfish farms. The test of difference showed that there is a highly significant difference in the level of conversion of rice fields into catfish farms when grouped according to rice farm area. There is no significant difference in the level of conversion of rice fields into catfish farms when grouped according to demographic profile such as age, sex, educational attainment, seminars or training attended and high length of experience. The test of relationship showed that there is a significant relationship between the level of conversion of rice farming and the current status of catfish farming. Instead of fishing in the rivers, farmers may convert the lower portion of their rice fields into fish ponds. However, the test of relationship showed that there is no significant relationship between the level of conversion and the current status of rice farming, government programs on rice production, and environmental conditions.
Integrated Organic Farming for Community Development Effectively Bridges the Gaps in Agricultural Instruction, Research, and Extension: Experience of a Public University in an Asian Developing Country
Authors: GARAN LINA M. 
Published: November 2016

This study was conducted in 2011 to 2012 under the aegis of the Cagayan State University-Sanchez Mira campus and the National Economic Development Authority under its Productivity Enhancement Program. The study employed technology-demonstration on organic farming as an entry point in the community. Using the descriptive design, 90 farmers were trained on organic farming technologies and structured survey questionnaire and interviews were used to document the results. The concept was designed to facilitate farmers’ adoption of sustainable and environment-friendly technology in organic farming by integrating the following components: On-Site School on Organic Farming, Technology-Demonstration, Extension and Technical Assistance, and Research. The on-site school included greenhouses, field research, and techno-demo plots on vegetable and livestock, vermi-compost, apiary, and houses for native pigs and chickens. To showcase organic farming practices, a field day was conducted which was attended by 165 farmers, entrepreneurs, and other stakeholders. Finally, the results showed that 90%, 80%, and 85% of the farmers from the three municipalities followed the technologies demonstrated to them. Around 85% of the total respondents reported an 80% increase in their monthly income. This was attributed to production of food and farm inputs. These results conclude that technology-demonstration was effective in bridging the gaps in agricultural instruction, research, and extension for the adaptation of farmers.
Debates—Stochastic subsurface hydrology from theory to practice: The relevance of stochastic subsurface hydrology to practical problems of contaminant transport and remediation. What is characterization and stochastic theory good for?
Authors: Fiori A. , Cvetkovic V. , Dagan G. , Attinger S. , Bellin A. , Dietrich P. , Zech A. , Teutsch G. 
Published: November 2016

AbstractThe emergence of stochastic subsurface hydrology stemmed from the realization that the random spatial variability of aquifer properties has a profound impact on solute transport. The last four decades witnessed a tremendous expansion of the discipline, many fundamental processes and principal mechanisms being identified. However, the research findings have not impacted significantly the application in practice, for several reasons which are discussed. The paper discusses the current status of stochastic subsurface hydrology, the relevance of the scientific results for applications and it also provides a perspective to a few possible future directions. In particular, we discuss how the transfer of knowledge can be facilitated by identifying clear goals for characterization and modeling application, relying on recent recent advances in research in these areas.
Modeled Chl:C ratio and derived estimates of phytoplankton carbon biomass and its contribution to total particulate organic carbon in the global surface ocean
Authors: Arteaga Lionel , Pahlow Markus , Oschlies Andreas 
Published: November 2016

AbstractChlorophyll (Chl) is a distinctive component of autotrophic organisms, often used as an indicator of phytoplankton biomass in the ocean. However, assessment of phytoplankton biomass from Chl relies on the accurate estimation of the Chl:carbon(C) ratio. Here we present global patterns of Chl:C ratios in the surface ocean obtained from a phytoplankton growth model that accounts for the optimal acclimation of phytoplankton to ambient nutrient, light, and temperature conditions. The model agrees largely with observed/expected global patterns of Chl:C. Combining our Chl:C estimates with satellite Chl and particulate organic carbon (POC), we infer phytoplankton C concentration in the surface ocean and its contribution to the total POC pool. Our results suggest that the portion of POC corresponding to living phytoplankton is higher in subtropical latitudes and less productive regions (∼30–70%) and decreases to ∼10–30% toward high latitudes and productive regions. An important caveat of our model is the lack of iron limiting effects on phytoplankton physiology. Comparison of our predicted phytoplankton biomass with an independent estimate of total POC reveals a positive correlation between nitrate concentrations and nonphotosynthetic POC in the surface ocean. This correlation disappears when a constant Chl:C is applied. Our analysis is not constrained by assumptions of constant Chl:C or phytoplankton:POC ratio, providing a novel independent analysis of phytoplankton biomass in the surface ocean. These results highlight the importance of accounting for the variability in Chl:C and its application in distinguishing the autotrophic and heterotrophic components in the assemblage of the marine plankton ecosystem.
Dynamics of primary productivity in the northern South China Sea over the past 24,000 years
Authors: Zhang Hongrui , Liu Chuanlian , Jin Xiaobo , Shi Jiangnan , Zhao Shaohua , Jian Zhimin 
Published: November 2016

AbstractIn this study, paleoproductivity on millennial scales was precisely reconstructed from core MD12‐3428cq in the northern South China Sea (SCS) over the past 24 kyr, based on a transfer function derived from the strong exponential negative correlation between relative abundance of Florisphaera profunda (%FP) in core top sediments and basin‐wide satellite‐based primary productivity (PP) in the SCS. To detect the potential driving mechanisms of PP, correlation analyses were carried out among our PP records and other paleoenvironment parameters. PP peaked during 18–15 ka in parallel with the strong East Asian Winter Monsoon (EAWM). From 15 ka to the early Holocene, a decrease in PP coincided with sea level progradation and weakening of EAWM, which ultimately reduced fluvial nutrient levels and wind‐driven upper water column mixing. Since the middle Holocene, gradually more frequent El Niño‐Southern Oscillation (ENSO) events have taken place, further decreasing PP by injecting oligotrophic Kuroshio water masses into the northern SCS. Associated findings conclusively indicated that the main controlling factors of PP in the northern SCS have shifted from EAWM (glacial) to ENSO (interglacial) over the past 24 kyr.
Imaging crustal structure beneath the southern Appalachians with wavefield migration
Authors: Hopper E. , Fischer K. M. , Rondenay S. , Hawman R. B. , Wagner L. S. 
Published: November 2016

AbstractTo constrain crustal structures in the southern Appalachians and the suture zone with the Gondwanan‐affinity Suwannee terrane, we applied the 2‐D generalized Radon transform wavefield migration method to the scattered incident P wavefield recorded by the EarthScope Southeastern Suture of the Appalachian Margin Experiment and adjacent Transportable Array stations. We resolve the root of thickened crust beneath the high topography of the Blue Ridge Mountains and estimate its density contrast with the mantle to be only 104 ± 20 kg/m3. A weak velocity contrast across the crustal root Moho is observed and may be related to an ongoing crustal delamination event, possibly contributing to local tectonic rejuvenation. Beneath the Suwannee terrane, we confirm prior observations of a gently south‐southeastward dipping crustal suture, indicating the terminal collision of Laurentia and Gondwana involved several hundred kilometers of overthrusting.
Detection of human‐induced evapotranspiration using GRACE satellite observations in the Haihe River basin of China
Authors: Pan Yun , Zhang Chong , Gong Huili , Yeh Pat J.‐F. , Shen Yanjun , Guo Ying , Huang Zhiyong , Li Xiaojuan 
Published: November 2016

AbstractRegional evapotranspiration (ET) can be enhanced by human activities such as irrigation or reservoir impoundment. Here the potential of using Gravity Recovery and Climate Experiment (GRACE) terrestrial water storage data in water budget calculations to detect human‐induced ET change is investigated over the Haihe River basin of China. Comparison between GRACE‐based monthly ET estimate (2005–2012) and Global Land Data Assimilation System (GLDAS)‐modeled ET indicates that human‐induced ET due to intensive groundwater irrigation from March to May can only be detected by GRACE. GRACE‐based ET (521.7 ± 21.1 mm/yr), considerably higher than GLDAS ET (461.7 ± 29.8 mm/yr), agrees well with existing estimates found in the literature and indicates that human activities contribute to a 12% increase in ET. The double‐peak seasonal pattern of ET (in May and August) as reported in published studies is well reproduced by GRACE‐based ET estimate. This study highlights the unique capability of GRACE in detecting anthropogenic signals over regions with large groundwater consumption.
Skillful seasonal forecasts of Arctic sea ice retreat and advance dates in a dynamical forecast system
Authors: Sigmond M. , Reader M. C. , Flato G. M. , Merryfield W. J. , Tivy A. 
Published: November 2016

AbstractThe need for skillful seasonal forecasts of Arctic sea ice is rapidly increasing. Technology to perform such forecasts with coupled atmosphere‐ocean‐sea ice systems has only recently become available, with previous skill evaluations mainly limited to area‐integrated quantities. Here we show, based on a large set of retrospective ensemble model forecasts, that a dynamical forecast system produces skillful seasonal forecasts of local sea ice retreat and advance dates—variables that are of great interest to a wide range of end users. Advance dates can generally be skillfully predicted at longer lead times (~5 months on average) than retreat dates (~3 months). The skill of retreat date forecasts mainly stems from persistence of initial sea ice anomalies, whereas advance date forecasts benefit from longer time scale and more predictable variability in ocean temperatures. These results suggest that further investments in the development of dynamical seasonal forecast systems may result in significant socioeconomic benefits.
Inverse electron energy dispersion from moving auroral forms
Authors: Cameron Taylor , Knudsen David 
Published: November 2016

AbstractNumerous published examples of energy‐dispersed bursts show electron energies reaching as high as several keV and decaying to lower energies over a fraction of 1 s. This signature has been interpreted by some authors as due to impulsive acceleration to a broad range of energies in a localized region and by others as the result of impulsive, dispersive Alfvén waves, in which case the acceleration takes place over an extended distance along magnetic field lines. A survey by the Suprathermal (0–350 eV) Electron Imager on the Enhanced Polar Outflow Probe (ePOP) in the topside ionosphere has produced examples of high‐to‐low (“regular”) energy dispersion, but also a smaller number of examples exhibiting low‐to‐high (“inverse”) dispersion, which to our knowledge has not been reported before. Motivated by a recent report of regular electron dispersion produced by auroral rays moving faster than the E × B drift speed, we investigate a heuristic model of electron acceleration within a region of uniform electric field parallel to B which extends a distance La along magnetic field lines. We show that in addition to a broad range of energies, this model produces inverse dispersion when the detector is less than La beneath the bottom of the acceleration region and regular dispersion for detector distances larger than La. This simple model is meant to inform future efforts to construct a more physical model of suprathermal electron acceleration within moving auroral forms and suggests that inverse dispersion indicates relative proximity to an altitude‐extended acceleration region.
Predicting electromagnetic ion cyclotron wave amplitude from unstable ring current plasma conditions
Authors: Fu Xiangrong , Cowee Misa M. , Jordanova Vania K. , Gary S. Peter , Reeves Geoffrey D. , Winske Dan 
Published: November 2016

AbstractElectromagnetic ion cyclotron (EMIC) waves in the Earth's inner magnetosphere are enhanced fluctuations driven unstable by ring current ion temperature anisotropy. EMIC waves can resonate with relativistic electrons and play an important role in precipitation of MeV radiation belt electrons. In this paper, we investigate the excitation and saturation of EMIC instability in a homogeneous plasma using both linear theory and nonlinear hybrid simulations. We have explored a four‐dimensional parameter space, carried out a large number of simulations, and derived a scaling formula that relates the saturation EMIC wave amplitude to initial plasma conditions. Such scaling can be used in conjunction with ring current models like ring current‐atmosphere interactions model with self‐consistent magnetic field to provide global dynamic EMIC wave maps that will be more accurate inputs for radiation belt modeling than statistical models.
Remote sensing of mesospheric dust layers using active modulation of PMWE by high‐power radio waves
Authors: Mahmoudian A. , Mohebalhojeh A. R. , Farahani M. M. , Scales W. A. , Kosch M. 
Published: November 2016

AbstractThis paper presents the first study of the modulation of polar mesospheric winter echoes (PMWE) by artificial radio wave heating using computational modeling and experimental observation in different radar frequency bands. The temporal behavior of PMWE response to HF pump heating can be employed to diagnose the charged dust layer associated with mesospheric smoke particles. Specifically, the rise and fall time of radar echo strength as well as relaxation and recovery time after heater turn‐on and turnoff are distinct parameters that are a function of radar frequency. The variation of PMWE strength with PMWE source region parameters such as electron‐neutral collision frequency, photodetachment current, electron temperature enhancement ratio, dust density, and radius is considered. The comparison of recent PMWE measurements at 56 MHz and 224 MHz with computational results is discussed, and dust parameters in the PMWE generation regime are estimated. Predictions for HF PMWE modification and its connection to the dust charging process by free electrons is investigated. The possibility for remote sensing of dust and plasma parameters in artificially modified PMWE regions using simultaneous measurements in multiple frequency bands are discussed.
Nitrate source apportionment using a combined dual isotope, chemical and bacterial property, and Bayesian model approach in river systems
Authors: Xia Yongqiu , Li Yuefei , Zhang Xinyu , Yan Xiaoyuan 
Published: November 2016

AbstractNitrate (NO3−) pollution is a serious problem worldwide, particularly in countries with intensive agricultural and population activities. Previous studies have used δ15N‐NO3− and δ18O‐NO3− to determine the NO3− sources in rivers. However, this approach is subject to substantial uncertainties and limitations because of the numerous NO3− sources, the wide isotopic ranges, and the existing isotopic fractionations. In this study, we outline a combined procedure for improving the determination of NO3− sources in a paddy agriculture‐urban gradient watershed in eastern China. First, the main sources of NO3− in the Qinhuai River were examined by the dual‐isotope biplot approach, in which we narrowed the isotope ranges using site‐specific isotopic results. Next, the bacterial groups and chemical properties of the river water were analyzed to verify these sources. Finally, we introduced a Bayesian model to apportion the spatiotemporal variations of the NO3− sources. Denitrification was first incorporated into the Bayesian model because denitrification plays an important role in the nitrogen pathway. The results showed that fertilizer contributed large amounts of NO3− to the surface water in traditional agricultural regions, whereas manure effluents were the dominant NO3− source in intensified agricultural regions, especially during the wet seasons. Sewage effluents were important in all three land uses and exhibited great differences between the dry season and the wet season. This combined analysis quantitatively delineates the proportion of NO3− sources from paddy agriculture to urban river water for both dry and wet seasons and incorporates isotopic fractionation and uncertainties in the source compositions.
Seasonal hyporheic dynamics control coupled microbiology and geochemistry in Colorado River sediments
Authors: Danczak Robert E. , Sawyer Audrey H. , Williams Kenneth H. , Stegen James C. , Hobson Chad , Wilkins Michael J. 
Published: November 2016

AbstractRiverbed microbial communities play an oversized role in many watershed ecosystem functions, including the processing of organic carbon, cycling of nitrogen, and alterations to metal mobility. The structure and activity of microbial assemblages depend in part on geochemical conditions set by river‐groundwater exchange or hyporheic exchange. To assess how seasonal changes in river‐groundwater mixing affect these populations in a snowmelt‐dominated fluvial system, vertical sediment and pore water profiles were sampled at three time points at one location in the hyporheic zone of the Colorado River and analyzed by using geochemical measurements, 16S rRNA gene sequencing, and ecological modeling. Oxic river water penetrated deepest into the subsurface during peak river discharge, while under base flow conditions, anoxic groundwater dominated shallower depths. Over a 70 cm thick interval, riverbed sediments were therefore exposed to seasonally fluctuating redox conditions and hosted microbial populations statistically different from those at both shallower and deeper locations. Additionally, microbial populations within this zone were shown to be the most dynamic across sampling time points, underlining the critical role that hyporheic mixing plays in constraining microbial abundances. Given such mixing effects, we anticipate that future changes in river discharge in mountainous, semiarid western U.S. watersheds may affect microbial community structure and function in riverbed environments, with potential implications for biogeochemical processes in riparian regions.
Biophysical controls over concentration and depth distribution of soil organic carbon and nitrogen in desert playas
Authors: McKenna Owen P. , Sala Osvaldo E. 
Published: November 2016

AbstractPlaya wetlands are important areas of soil organic carbon and nutrient storage in drylands. We conducted this study to assess how catchment biophysical variables control soil organic carbon and nitrogen in playas and how playas function differently than upland ecosystems. We found that playa organic carbon and nitrogen corresponded primarily with catchment vegetation cover and secondarily with catchment area, slope, and soil texture. The effect of increased organic matter production associated with high catchment vegetation cover overshadowed the potential effect of reduced run‐on. We also found soil carbon and nitrogen profiles to be significantly shallower in playas than uplands. This trend is correlated with evidence of sedimentation and shallow‐rooted plants in playas. Upland soils had a deeper carbon and nitrogen profile, which correlated with organic matter being generated by deeply rooted vegetation. In playas, C:N ratios remained constant through depth but in uplands, C:N ratios increased through depth. We found evidence that differences in rooting depth distributions and soil texture may explain these C:N variations between uplands and playas. In uplands, clay concentration increased with depth, whereas in playas, clay concentration did not change with depth, which highlighted the important role of sedimentation in these ecosystems. Our results suggest that small changes in playa catchment vegetation cover in response to climate change or grazing intensity would greatly impact playa soil organic carbon and nitrogen stocks. This effect would be due to the playa soils dependence on allochthonous organic matter and the large upland area that drains into playas.
Variable phase propagation velocity for long‐range lightning location system
Authors: Liu Zhongjian , Koh Kuang Liang , Mezentsev Andrew , Enno Sven‐Erik , Sugier Jacqueline , Füllekrug Martin 
Published: November 2016

AbstractThe electromagnetic wave propagation velocity at low radio frequencies is an important input parameter for lightning location systems that use time of arrival (TOA) method. This velocity is normally fixed at or near the speed of light. However, this study finds that the radio waves from two submarine communication transmitters at 20.9 kHz and 23.4 kHz exhibit phase propagation velocities that are ~0.51% slower and ~0.64% faster than the speed of light as a result of sky wave contributions and ground effects. Therefore, a novel technique with a variable phase propagation velocity is implemented for the first time in the TOA method and applied to electric field recordings with a long‐baseline lightning location system that consists of four radio receivers in western Europe. The lightning locations inferred from variable velocities improve the accuracy of locations inferred from a fixed velocity by ~0.89–1.06 km when compared to the lightning locations reported by the UK MetOffice. The normal distributions of the observed phase propagation velocities in small geographic areas are not centered at the speed of light. Consequently, representative velocities can be calculated for many small geographic areas to produce a velocity map over central France where numerous lightning discharges occurred. This map reflects the impact of sky waves and ground effects on the calculation of lightning locations as a result of the network configuration. It is concluded that the use of variable phase propagation velocities mitigates the influence of sky waves and ground effects in long‐range lightning location networks.