scholarly journals Nitrate Runoff Contributing from the Agriculturally Intensive San Joaquin River Watershed to Bay-Delta in California

2019 ◽  
Vol 11 (10) ◽  
pp. 2845 ◽  
Author(s):  
Ruoyu Wang ◽  
Huajin Chen ◽  
Yuzhou Luo ◽  
Patrick Moran ◽  
Michael Grieneisen ◽  
...  
Keyword(s):  
Critical Role ◽  
Agricultural Landscapes ◽  
Nitrogen Loading ◽  
Aquatic Weed ◽  
Ecological Implication ◽  
Aquatic Weeds ◽  
River Watershed ◽  
San Joaquin River ◽  
Study Results ◽  
San Joaquin River Watershed

Nitrogen loading from agricultural landscapes can trigger a cascade of detrimental effects on aquatic ecosystems. Recently, the spread of aquatic weed infestations (Eichhornia crassipes, Egeria densa, Ludwigia spp., and Onagraceae) in the Sacramento-San Joaquin Delta of northern California has raised concerns, and nitrogen loading from California’s intensive farming regions is considered as one of the major contributors. In this study, we employed the Soil and Water Assessment Tool (SWAT) to simulate nitrogen exports from the agriculturally intensive San Joaquin River watershed to the Delta. The alternate tile drainage routine in SWAT was tested against monitoring data in the tile-drained area of the watershed to examine the suitability of the new routine for a tile nitrate simulation. We found that the physically based Hooghoudt and Kirkham tile drain routine improved model performance in representing tile nitrate runoff, which contributed to 40% of the nitrate loading to the San Joaquin River. Calibration results show that the simulated riverine nitrate loads matched the observed data fairly well. According to model simulation, the San Joaquin River plays a critical role in exporting nitrogen to the Delta by exporting 3135 tons of nitrate-nitrogen annually, which has a strong ecological implication in supporting the growth of aquatic weeds, which has impeded water flow, impairs commercial navigation and recreational activities, and degrades water quality in Bay-Delta waterways. Since nitrate loadings contributed by upstream runoff are an important nutrient to facilitate weed development, our study results should be seen as a prerequisite to evaluate the potential growth impact of aquatic weeds and scientific evidence for area-wide weed control decisions.

scholarly journals Hydrologic sensitivity of the Upper San Joaquin River Watershed in California to climate change scenarios

2012 ◽  
Vol 44 (4) ◽  
pp. 723-736 ◽  
Author(s):  
Zili He ◽  
Zhi Wang ◽  
C. John Suen ◽  
Xiaoyi Ma
Keyword(s):  
Climate Change ◽  
Sierra Nevada ◽  
Climate Change Scenarios ◽  
Intergovernmental Panel ◽  
Hydrological Simulation ◽  
River Watershed ◽  
System Sensitivity ◽  
Hspf Model ◽  
San Joaquin River ◽  
San Joaquin River Watershed

To examine the hydrological system sensitivity of the southern Sierra Nevada Mountains of California to climate change scenarios (CCS), five headwater basins in the snow-dominated Upper San Joaquin River Watershed (USJRW) were selected for hydrologic simulations using the Hydrological Simulation Program-Fortran (HSPF) model. A pre-specified set of CCS as projected by the Intergovernmental Panel on Climate Change (IPCC) were adopted as inputs for the hydrologic analysis. These scenarios include temperature increases between 1.5 and 4.5 °C and precipitation variation between 80 and 120% of the baseline conditions. The HSPF model was calibrated and validated with measured historical data. It was then used to simulate the hydrologic responses of the watershed to the projected CCS. Results indicate that the streamflow of USJRW is sensitive to the projected climate change. The total volume of annual streamflow would vary between −41 and +16% compared to the baseline years (1970–1990). Even if the precipitation remains unchanged, the total annual flow would still decrease by 8–23% due to temperature increases. A larger portion of the streamflow would occur earlier in the water year by 15–46 days due to the temperature increases, causing higher seasonal variability of streamflow.

scholarly journals The Moderating Effect of Debriefing on Learning Outcomes of IVR-Based Instruction: An Experimental Research

2021 ◽  
Vol 11 (21) ◽  
pp. 10426
Author(s):  
Qinna Feng ◽  
Heng Luo ◽  
Wenhao Li ◽  
Ying Chen ◽  
Jiakai Zhang
Keyword(s):  
Virtual Reality ◽  
Experiential Learning ◽  
Learning Environments ◽  
Learning Experience ◽  
Controlled Trial ◽  
Critical Role ◽  
Moderating Effect ◽  
Learning Program ◽  
Study Results ◽  
Based Instruction

With its ability to afford immersive and interactive learning experiences, virtual reality has been widely used to support experiential learning, of which the learning effectiveness is promoted by the instructional component of debriefing. The current literature on debriefing mainly focuses on the traditional learning contexts while little is known on its effectiveness in immersive virtual reality (IVR) learning environments. Based on the theories of experiential learning and debriefing, this study designed a debriefing strategy based on simulated learning experience and investigated its effectiveness on knowledge and behavioral learning in an IVR learning program, using a randomized controlled trial with 77 elementary students from Hubei province in China. The study results support the efficacy of IVR on improving knowledge acquisition and behavioral performance, and reveal a significant moderating effect of debriefing on the effectiveness of IVR learning environments. The study confirms the critical role of debriefing in IVR-based instruction and provides theoretical and practical implications for the design and implementation of effective IVR learning environments.

A Review of Literature on Adjustment Issues of International Students

2016 ◽  
pp. 223-242
Author(s):  
Eunjin Hwang ◽  
Nara M. Martirosyan ◽  
George W. Moore
Keyword(s):  
International Students ◽  
Theoretical Model ◽  
Support Services ◽  
Critical Review ◽  
Academic Adjustment ◽  
Critical Role ◽  
Review Of Literature ◽  
Study Results ◽  
Diverse Groups ◽  
Adjustment Issues

There is a scarcity of studies wherein a critical review or synthesis exists on the adjustment of international students with a few exceptional works. Therefore, through critical analyses of recent studies from various disciplines, the authors examine conceptual applications of existing models or typologies incorporated in previous studies, and redefine the nature of problems encountered by international students with a synthesis of study results on their adjustment issues: psychological, socio-cultural, and academic adjustment. Furthermore, suggestions for both practitioners and researchers are elaborated in the chapter. These suggestions include creating a new conceptual/theoretical model, emphasizing a critical role played by the host university, and tailoring support services to satisfy specific needs of diverse groups of international students within the specific campus context.

Optimization of nitrogen removal from piggery waste by nitrite nitrification

2002 ◽  
Vol 45 (12) ◽  
pp. 89-96 ◽  
Author(s):  
Y. Eum ◽  
E. Choi
Keyword(s):  
Nitrogen Removal ◽  
Volume Ratio ◽  
Ph Control ◽  
Nitrogen Loading ◽  
Optimum Operating ◽  
Optimum Operating Condition ◽  
Nitrogen Loads ◽  
Study Results ◽  
Waste Characteristics ◽  
Nitrification And Denitrification

The piggery waste characteristics greatly vary with types of manure collections and the amount of water used. If solids are separated well, the waste strength will be greatly reduced resulting in lower TCOD/TKN ratio of 4 (average). If solids are separated by a mechanical scraper, some solids will remain and the waste strength will be increased with a TCOD/TKN ratio of 7. This study was conducted to find an optimum operating condition for nitrogen removal with these two ratios. Nitrite nitrification was targeted because it could be a short cut process for savings in oxygen for nitrification and carbon requirements for denitrification. The study results indicated that nitrogen loading rate and pH were the most important factors to be considered for stable nitrite nitrification. The applicable nitrogen loads were estimated to be 0.3 to 2.0 kgTKN/oxic m3/d for high TCOD/TKN ratio without pH control. With higher pH > 8, NO2N/NOxN ratios in oxic stages even with lower nitrogen loads were increased. The SBR with low TCOD/TKN ratio less than 4 required additional alkalinity. For a complete denitrification, the influent TCOD/TKN ratio must exceed 6 with oxic/total reactor volume ratio of 0.5. Nitrite nitrification and denitrification could save about 35% in tank volume and 50% in carbon requirement, respectively. However, 9.5% oxygen saving could be expected during the operation with low TCOD/TKN ratio. The elevated temperature due to the heat released from COD removal also enhanced microbial activities for nitrification and denitrification as well as ammonia stripping. However, careful attention must be provided for the reactor temperature not to inhibit the nitrification process.

Improving child and adolescent adherence to evidence-based mental health interventions

2011 ◽  
Vol 26 (S2) ◽  
pp. 1307-1307
Author(s):  
R. Gearing ◽  
C. Schwalbe
Keyword(s):  
Mental Health ◽  
Mental Health Problems ◽  
Critical Role ◽  
Psychosocial Interventions ◽  
Adolescent Mental Health ◽  
Child And Adolescent ◽  
Drop Out ◽  
Evidence Based ◽  
Client Participation ◽  
Study Results

IntroductionThe exponential growth of evidence-based practice (EBP) interventions offers clinicians a growing number of empirically-supported psychosocial treatments for youth mental disorders. These interventions are likely to be ineffective with clients who drop out of treatment prematurely or who fail to adhere to the required intervention protocols. However, despite the critical role of client adherence, systematic evidence about strategies to support client adherence is lacking.ObjectivesThe primary aim of this present study is to establish an empirical base for developing adjunctive adherence promoters to enhance client participation in psychosocial interventions.MethodsMental health child and adolescent intervention researchers who published RCT on three psychosocial interventions (CBT, IPT. Psycho-ed) were surveyed on type, use, and efficacy of intervention adherence promoters.ResultsInterventions included an average of 13.4 sessions (SD = 7.8) across 5 months. Most researchers reported using multiple adherence promoting interventions throughout their studies. On average, respondents reported using little more than one promoter per session and devoting approximately 12.4 minutes per session on all adherence promoters.ConclusionsResults of this study will assist practitioners and researchers in improving adherence to psychiatric interventions for children and adolescents. Specifically, study results fill gaps in the literature on active efforts to sustain and increase client adherence to treatment for childhood and adolescent mental health disorders. Findings of this study support best practices for adherence promotion and open new avenues for research into the tailoring of adherence to EBP interventions for child and adolescent mental health problems.

scholarly journals Influence of climate change on river discharges over the Sava River watershed in Bosnia and Herzegovina

Időjárás ◽  
2021 ◽  
Vol 125 (3) ◽  
pp. 449-462
Author(s):  
Slobodan Gnjato ◽  
Tatjana Popov ◽  
Dragutin Adžić ◽  
Marko Ivanišević ◽  
Goran Trbić ◽  
...  
Keyword(s):  
Air Temperature ◽  
Kendall Test ◽  
River Watershed ◽  
Study Results ◽  
Abrupt Changes ◽  
Sava River ◽  
Slope Estimator ◽  
Annual Scale ◽  
Hydroclimatic Variables ◽  
The Sava River

The paper examines changes in air temperature, precipitation, and river discharges on seasonal and annual scale over the Sava River watershed in Bosnia & Herzegovina during the period 1961–2016. Based upon data gathered from 11 meteorological stations and 3 hydrological stations, hydroclimatic variables trends were established by utilizing the nonparametric Mann-Kendall test and the nonparametric Sen’s slope estimator. The results show significant positive seasonal and annual trends (expect for autumn, during which upward trends were insignificant) in air temperature, whereas both positive and negative insignificant seasonal and annual precipitation trends are shown where determined for the entire watershed. Most prominent upward trends in air temperature were found in summer and afterwards in winter and spring, indicating a pronounced warming tendency over the Sava River watershed. Trends in river discharge displayed a negative tendency in all seasons. Nevertheless, a majority of estimated trends of river discharges were weak and statistically insignificant. Throughout the year, river discharges showed significant positive correlation with precipitation, whilst connection with air temperature was mostly significant and negative. The study results suggest that climate is an important factor affecting river regimes, as well as that changes in river discharges are reflecting recent abrupt changes in climatic variables.

Sign in / Sign up

Export Citation Format

Share Document