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Full-Text Articles in Physical Sciences and Mathematics

Fabrication Of Black Phosphorus Terahertz Photoconductive Antennas, Nathan Tanner Sawyers May 2023

Fabrication Of Black Phosphorus Terahertz Photoconductive Antennas, Nathan Tanner Sawyers

Physics Undergraduate Honors Theses

Terahertz (THz) photoconductive antennas (PCAs) using 40nm thin-film flakes of black phosphorus (BP) and hexagonal boron nitride (hBN) have been shown computationally to be capable of THz emission comparable to those based on GaAs [2]. In this paper, I briefly describe the scientific and practical interest in THz emissions and explain what warrants research into black phosphorus as a photoconductive semiconductor in THz devices. Furthermore, I outline the basic principle of how these antennas work and mention alternative designs produced by other researchers in the past. Finally, I summarize the fabrication process of these antennas, as well as the measurements …


Defining Critical Or Hydrologic Conditions As Sampled During The Joint Study, Brian E. Haggard, Erin Grantz, J. T. Scott Jul 2022

Defining Critical Or Hydrologic Conditions As Sampled During The Joint Study, Brian E. Haggard, Erin Grantz, J. T. Scott

Technical Reports

The “Joint Study” was conducted to fulfill the obligations of the second “Statement of Joint Principles and Actions” agreed to by the states of Arkansas and Oklahoma. The “Joint Study” affirmed the magnitude of Oklahoma’s Scenic River total phosphorus (TP) criteria (i.e., 0.037 mg/L), but it added the new caveat of applying the criteria to “critical conditions.” The primary purpose of this paper was to define “critical conditions” based on the range in base flow proportions (BFP) of total streamflow on days that were sampled in the “Joint Study,” where BFP is base flow discharge divided by total stream flow …


Field Evaluation Of Struvite As A Phosphorus Source, Niyi Sunday Omidire Dec 2021

Field Evaluation Of Struvite As A Phosphorus Source, Niyi Sunday Omidire

Graduate Theses and Dissertations

Phosphorus (P) is an element that is crucial in many biological processes in all forms of life and is not substitutable. Excess P in wastewaters leading to the degradation of receiving waters or eutrophication once released is a major environmental concern. Removal of excess P from wastewater as the mineral struvite (MgNH4PO4·6H2O) could be a promising solution to reduce P discharge into receiving waters and can potentially provide a valuable fertilizer-P source for agricultural production. The objectives of this project were to evaluate the effects of: 1) chemically precipitated struvite (CPST), compared to triple superphosphate (TSP) and an unamended control …


Nutrient Sources, Loads And Trends Vary Spatially And Temporally Within The Poteau River Watershed And Lake Wister, Oklahoma, Abbie Lasater Jul 2021

Nutrient Sources, Loads And Trends Vary Spatially And Temporally Within The Poteau River Watershed And Lake Wister, Oklahoma, Abbie Lasater

Graduate Theses and Dissertations

Excess inputs of nutrients and sediments jeopardize drinking water sources, aquatic life habitats, and aesthetic quality of freshwater resources for recreation. The purpose of this dissertation was to analyze long-term water quality trends and loads in the Upper Poteau River Watershed (UPRW) and the Lake Wister Watershed (LWW), and analyze internal phosphorus (P) loads in Lake Wister, Oklahoma. Additionally, this dissertation sought to review the literature for methods of prioritizing subwatersheds for watershed management using watershed models, implement a cost efficient method to remotely monitor streamflow and estimate constituent loads in small-scale watersheds, and finally, to validate the Soil Water …


Corn And Soybean Response To Wastewater-Recycled Phosphorus Fertilizers, Shane Ylagan Dec 2020

Corn And Soybean Response To Wastewater-Recycled Phosphorus Fertilizers, Shane Ylagan

Crop, Soil and Environmental Sciences Undergraduate Honors Theses

The ability to recycle phosphorus (P) from wastewaters could provide a sustainable, continuous source of P that might also help protect surface water quality from P enrichment. The mineral struvite (MgNH4PO4·6H2O) is an understudied material that can be created from Pcontaining wastewater and has been shown to have agricultural fertilizer value. The objective of this study was to evaluate the effects of electrochemically precipitated struvite (ECST), chemically precipitated struvite (Crystal Green; CG), diammonium phosphate (DAP), monoammonium phosphate (MAP), rock phosphate (RP), and triple super phosphate (TSP) on corn (Zea mays) and soybean (Glycine max) response in a 79-day greenhouse pot …


The Release, Transport, And Utilization Of Phosphorus From Bed-Sediments: A Study Of A Eutrophic Littoral Cove On Beaver Lake In Northwest Arkansas, James A. Mccarty May 2020

The Release, Transport, And Utilization Of Phosphorus From Bed-Sediments: A Study Of A Eutrophic Littoral Cove On Beaver Lake In Northwest Arkansas, James A. Mccarty

Graduate Theses and Dissertations

Eutrophication of surface waters not only impacts the environment but also water treatment processes, the most significant of which is from the effects of algae. During peak algal growth in many southern U.S. reservoirs, inflows that bring nutrients are at an annual minimum, and phosphorus released from bed-sediments is trapped in the hypolimnion. Littoral areas, described as the most productive zone of the lake, may be a possible source of phosphorus that fuels algal growth in the reservoir. I studied an isolated shallow cove in the War Eagle Creek arm of Beaver Lake in Northwest Arkansas to measure, quantify, and …


Wayne E. Sabbe Arkansas Soil Fertility Studies 2019, Nathan A. Slaton May 2020

Wayne E. Sabbe Arkansas Soil Fertility Studies 2019, Nathan A. Slaton

Arkansas Agricultural Experiment Station Research Series

Rapid technological changes in crop management and production require that the research efforts be presented in an expeditious manner. The contributions of soil fertility and fertilizers are major production factors in all Arkansas crops. The studies described within will allow producers to compare their practices with the university’s research efforts. Additionally, soil-test data and fertilizer sales are presented to allow comparisons among years, crops, and other areas within Arkansas.


Corn Response To Wastewater-Recycled Phosphorus Fertilizers, Shane R. Ylagan, Kristofor R. Brye Jan 2020

Corn Response To Wastewater-Recycled Phosphorus Fertilizers, Shane R. Ylagan, Kristofor R. Brye

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

The ability to recycle phosphorus (P) from wastewaters could provide a sustainable, continuous source of P that might also help protect surface water quality from P enrichment. The mineral struvite (MgNH4PO4 · 6H2O) is an understudied material that can be created from P- and nitrogen (N)-containing wastewater and has been shown to have agricultural fertilizer value. The objective of this study was to evaluate the effects of electrochemically precipitated struvite (ECST), chemically precipitated struvite (Crystal Green; CG), diammonium phosphate (DAP), monoammonium phosphate (MAP), rock phosphate (RP), and triple superphosphate (TSP) on corn (Zea mays) response in a greenhouse pot study. …


Effect Of Macrograzers (Campostoma Spp. And Faxonius Spp.) On Periphyton In Ozark Streams With Considerations Given To Macrograzer Biomass, Phosphorus, And Season: Mensurative And Manipulative Studies, Kayla R. Sayre Dec 2018

Effect Of Macrograzers (Campostoma Spp. And Faxonius Spp.) On Periphyton In Ozark Streams With Considerations Given To Macrograzer Biomass, Phosphorus, And Season: Mensurative And Manipulative Studies, Kayla R. Sayre

Graduate Theses and Dissertations

Nutrient and benthic algal biomass relationships can guide numeric nutrient criteria development in lotic systems. However, herbivorous macrograzers may confound this relationship by reducing the slope of the positive relationship between nutrients and periphyton biomass in streams. I conducted a mensurative field study to determine if stoneroller and crayfish abundance related to algal biomass at varying nutrient concentrations and manipulated macrograzer presence with electrical exclosures in streams to examine macrograzer effects on algal biomass and understand whether these effects on periphyton varied with total phosphorus (TP) or season. Macrograzer density was quantified across a TP gradient (n=15 streams; range = …


The Potential For Phosphorus Release From Floodplain Soils: Temporal Variability And Management Strategies, Megan Amanda Reavis Jan 2017

The Potential For Phosphorus Release From Floodplain Soils: Temporal Variability And Management Strategies, Megan Amanda Reavis

Graduate Theses and Dissertations

Soils may contain large amounts of legacy phosphorus (P) due to past application of excess fertilizers, releasing P during runoff and flood events. As the level of P in soils increases, the release of P from the soils increases, but the temporal fluctuations of this release are not well known. Experiments were conducted to examine 1) the variability of soluble reactive P (SRP) release from the soil throughout a year and 2) the effect of repeated flooding and drying cycles on release rates. Soil cores were collected 7 times throughout a year from 2 sites within the Watershed Research and …


Dietary Effects On The Stoichiometry Of Growth, Regulation, And Wastes Of Ozark Stream Insect Detritivores, Halvor Matthew Halvorson May 2016

Dietary Effects On The Stoichiometry Of Growth, Regulation, And Wastes Of Ozark Stream Insect Detritivores, Halvor Matthew Halvorson

Graduate Theses and Dissertations

A widespread stressor, anthropogenic nitrogen (N) and phosphorus (P) pollution can increase resource nutrient content and alter animal community composition in freshwater ecosystems. In this dissertation, I used ecological stoichiometry theory to examine effects of diet nutrient content and leaf litter type on growth, regulation, and wastes of aquatic invertebrate detritivores. I tested effects of leaf litter diet carbon:phosphorus (C:P) on growth and stoichiometric regulation of the detritivorous caddisfly Pycnopsyche lepida and used results to determine a threshold elemental ratio of oak litter C:P=1620 that confers peak growth of this species. This empirical, growth-based approach provided a more accurate estimate …


Validation Of Soil-Test-Based Phosphorus And Potassium Fertilizer Recommendations For Rice And Soybean, Matthew Scott Fryer Dec 2015

Validation Of Soil-Test-Based Phosphorus And Potassium Fertilizer Recommendations For Rice And Soybean, Matthew Scott Fryer

Graduate Theses and Dissertations

The science of soil-testing for nutrient management and fertilizer recommendations is widely accepted among scientists and agronomists. Although this science is unsurpassed in predicting soil nutrient availability, soil-test interpretations are seldom validated. Major research objectives for irrigated soybean [Glycine max (L.) Merr.] and direct-seeded, delayed-flood rice (Oryza sativa L.) were to: i) validate the accuracy of Mehlich-3 soil-test P (STP) and K (STK) interpretations and ii) published critical tissue-P and -K interpretations in predicting the yield response to fertilizer at different significance levels (p≤0.05 to 0.25), iii) examine how seed nutrient concentrations are influenced by fertilization and crop response to …


Reducing Nutrient Runoff From Poultry Production Facilities Using Locally-Sourced Iron And Aluminum Byproducts, Sheri Lynn Herron Jul 2015

Reducing Nutrient Runoff From Poultry Production Facilities Using Locally-Sourced Iron And Aluminum Byproducts, Sheri Lynn Herron

Graduate Theses and Dissertations

Phosphorus (P) inputs to fresh waters can accelerate the eutrophication process. Agricultural nutrient runoff has been shown to be a contributor of P and nitrogen (N). Broiler production areas were evaluated for their potential to contribute P and N to runoff. Broiler house dust (BHD) samples were analyzed and compared to broiler litter (BL), rainfall simulations were conducted on plots adjacent to broiler house fans to evaluate nutrient enrichment in runoff from deposited dust, and runoff was automatically sampled at two culverts draining the land around broiler houses. Following this, an on-farm byproduct containment and nutrient removal structure was designed …


Estimating Nitrogen Fixation Rates, Importance, And Short-Term Efficiency In Small, Temperate Reservoirs Using Delta15n Techniques, Bryant Christopher Baker May 2014

Estimating Nitrogen Fixation Rates, Importance, And Short-Term Efficiency In Small, Temperate Reservoirs Using Delta15n Techniques, Bryant Christopher Baker

Graduate Theses and Dissertations

Nitrogen (N2) fixation can give certain species of cyanobacteria a competitive advantage in lake and reservoir phytoplankton. These species of cyanobacteria, along with others that cannot fix N2, can form toxic compounds that impair water quality when present in high concentrations. N2 fixation rates may be substantial in small (< 1.0 km2), temperate reservoirs since these systems experience thermal stratification and often nitrogen (N) limitation throughout a substantial proportion of the year. However, the effects of N2 fixation on N cycling, alleviation of short-term N limitation, and water quality are not well-understood. A mesocosm experiment and ecosystem-scale observational study were conducted to 1) determine the efficiency of N2 fixation under varying N relative to phosphorus (P) supply, 2) examine the effects of N2 fixation on autotrophic biomass accumulation and microcystin production, and 3) measure N2 fixation rates and importance to autotrophic N demand and zooplankton N assimilation. Results of the mesocosm experiment indicated that N2 fixation was increased at low N:P supply under high P. However, N2 fixation was inefficient at alleviating N limitation when fixed N was the primary source of N. Additionally, microcystin production occurred only at high N:P supply when N2 fixation was low, indicating that reducing external N inputs may have a positive effect on water quality. Results of whole-reservoir determination of N2 fixation using seston δ15N natural abundances indicated that N2 fixation rates throughout the warm season were substantial and influenced by water temperature. Annual N2 fixation rates ranged from 2.2 - 6.6 g N m-2 yr-1, and contributed up to 19% of the annual autotrophic N demand. Zooplankton were assimilating fixed N in most of the study reservoirs, representing a possible mechanism of ecosystem fixed N retention. Collectively, these results suggest that N2 fixation plays a substantial role in N cycling in small, temperate reservoirs, but likely cannot alleviate short-term N limitation.


The Potential Release Of Phosphorus In Floodplains, Maria S. Rossetti, Nicole K. Ownby, Erin Scott, Brian E. Haggard Jan 2014

The Potential Release Of Phosphorus In Floodplains, Maria S. Rossetti, Nicole K. Ownby, Erin Scott, Brian E. Haggard

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

In the Illinois River Watershed, there has been growing concern over elevated phosphorus concentrations in the water column. This study evaluated how much phosphorus is contributed from floodplain soils into surface waters, examining the relationship between the flux of phosphorus released and the amount of phosphorus stored in the soil. This was investigated by artificially inundating soil cores from four sites and determining the soluble reactive phosphorus concentrations of the overlying water and the levels of Water and Mehlich-3 extractable phosphorus in the soil. The flux of phosphorus to the overlying water ranged from 0.43 to 6.61 mg m-2 hr-1 …


Reducing Water Extractable Phosphorus In Poultry Litter Using Chitosan Treatment, Zachary Simpson, Brina Smith, David A. Zaharoff, Brian E. Haggard Jan 2014

Reducing Water Extractable Phosphorus In Poultry Litter Using Chitosan Treatment, Zachary Simpson, Brina Smith, David A. Zaharoff, Brian E. Haggard

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

Phosphorus (P) is an important factor in the eutrophication of freshwater, and watershed sources include effluent discharges and the landscape. Poultry litter applied to the landscape can be a potential source of P, which is dependent on rainfall, runoff and dissolution. Chitosan, the deacetylated form of the biopolymer chitin, has been shown to have an effect on reducing water extractable phosphorus (WEP) in poultry litter when applied as a powder. The intent of this study was to measure the effect that poultry litter treatment (PLT), acetic acid and incubation time have on chitosan’s ability to reduce WEP in poultry litter. …


Water Quality Trends Across Select 319 Monitoring Sites In Northwest Arkansas, Bryan W. Bailey, Brian E. Haggard, Leslie B. Massey Jan 2012

Water Quality Trends Across Select 319 Monitoring Sites In Northwest Arkansas, Bryan W. Bailey, Brian E. Haggard, Leslie B. Massey

Technical Reports

Northwest Arkansas contains two 319 priority watersheds that the Arkansas Natural Resources Commission has identified as being impacted by point source and nonpoint source pollution (i.e., phosphorus, nitrogen, and sediment). This project specifically focused on determining water quality trends at select sites within the Illinois River (HUC# 11110103) and Beaver Reservoir (HUC# 11010001) priority watersheds, including Ballard Creek, Osage Creek, Illinois River, White River, West Fork White River and the Kings River where sufficient constituent data were available. Water quality trends were analyzed using flow‐adjusted constituent concentrations of phosphorus, nitrogen, sediment, sulfate and chloride, and parametric and non‐parametric statistical techniques …


Phosphorus Release From Bottom Sediments At Lake Wister, Oklahoma, Summer 2010, B.E. Haggard, J.T. Scott Jan 2011

Phosphorus Release From Bottom Sediments At Lake Wister, Oklahoma, Summer 2010, B.E. Haggard, J.T. Scott

Technical Reports

A previous reservoir model of Lake Wister, Oklahoma suggested that internal P sources were dominant, and that a watershed management plan need not be developed to address external sources. The objectives of this study were to collect intact sediment cores from three sites at Lake Wister and measure sediment O₂ demand (SOD) and soluble reactive P (SRP) release to the overlying water during lab incubations under quiescent conditions. The measured SOD rates were between 9.9 and 22.6 mg m⁻² hr⁻¹ on average across the three sites, where the shallow headwaters site had the least SOD. The SRP release rates were …


Continuation Of Water Quality Monitoring Of The Osage Creek Above The Highway 112 Bridge Near Cave Springs, Arkansas, Marc Nelson, Luanna Diffin May 2007

Continuation Of Water Quality Monitoring Of The Osage Creek Above The Highway 112 Bridge Near Cave Springs, Arkansas, Marc Nelson, Luanna Diffin

Technical Reports

The City of Rogers is one of the fastest growing communities in Arkansas. Located in Northwest Arkansas, Rogers lies in two primary watersheds; the Illinois River Watershed and Beaver Lake Watershed. The Illinois River Watershed receives municipal wastewater discharge from most of the metropolitan communities in Northwest Arkansas, along with nonpoint source urban and agricultural runoff. The Illinois River originates in Arkansas and flows west into Oklahoma where it is classified as a scenic river. The river has been a source of interstate disputes for a number of years. A federal interstate compact commission was established to mediate these disputes, …


Water Quality Sampling, Analysis And Annual Load Determinations For Tss, Nitrogen And Phosphorus In The Bayou Bartholomew At Garrett Bridge, Arkansas And Near Portland, Arkansas, Marc Nelson, Wade Cash, Keith Trost, Jennifer Purtle, Ralph Davis, K. Steele Jun 2006

Water Quality Sampling, Analysis And Annual Load Determinations For Tss, Nitrogen And Phosphorus In The Bayou Bartholomew At Garrett Bridge, Arkansas And Near Portland, Arkansas, Marc Nelson, Wade Cash, Keith Trost, Jennifer Purtle, Ralph Davis, K. Steele

Technical Reports

Water quality sampling stations were installed at the Bayou Bartholomew at Garrett Bridge, AR and near Portland, AR. These stations are coordinated with USGS gauging stations at the same locations. These stations are instrumented to collect samples at sufficient intervals across the hydrograph to accurately estimate the flux of total suspended solids, nitrogen and phosphorus in the River. Bayou Bartholomew watershed is about 437,000 hectares and is located in the south east corner of the state. The land use in the watershed is mostly in forest and cropland agriculture with some urban area. High turbidity levels and excessive silt loads …


Estimating Surface Runoff In The Illinois River Basin For The Management Of Nonpoint-Source Phosphorus Loads, Adam T. Mcclymont, Mary C. Savin, Brian E. Haggard Jan 2006

Estimating Surface Runoff In The Illinois River Basin For The Management Of Nonpoint-Source Phosphorus Loads, Adam T. Mcclymont, Mary C. Savin, Brian E. Haggard

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

With the growing concern about elevated phosphorus (P) concentrations in regional lakes, rivers, and streams, it is essential to investigate factors contributing to P transport from the landscape. Phosphorus fluxes from nonpoint sources, particularly land applications of poultry litter and other animal manures, are closely related to the amount and production of surface runoff. Daily stream discharge and the software program, Base Flow Index (BFI), were used to estimate the amount and temporal patterns of surface runoff at different locations within the Illinois River Basin, including selected tributaries in northwest Arkansas and northeast Oklahoma. Daily streamflow data from nine U.S. …


Method Analysis Of Laboratory Measures Of Stream Sediment And Water Phosphorus Equilibrium, Anna L. Erickson, Stephanie M. Williamson, Brian E. Haggard Jan 2004

Method Analysis Of Laboratory Measures Of Stream Sediment And Water Phosphorus Equilibrium, Anna L. Erickson, Stephanie M. Williamson, Brian E. Haggard

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

Elevated phosphorus concentrations in aquatic ecosystems of northwest Arkansas prompted an investigation of the effects of sample preparation and extraction methods on laboratory measures of sediment-phosphorus interactions. Two streams of contrasting phosphorus (P) concentrations were selected to determine the effect of using a CaCl2 solution instead of filtered stream water, refrigerated or dried sediments instead of fresh wet sediments, and vortexing the suspensions instead of shaking them. Sediment equilibrium P concentration (EPC0) and P buffering capacity (K) were used to determine differences in extraction methods. EPC0 and K from extractions using fresh sediments and a CaCl2 solution matching the electrical …


Illinois River Phosphorus Sampling Results And Mass Balance Computation, Marc Nelson, K.L. White, T.S. Soerens Jan 2002

Illinois River Phosphorus Sampling Results And Mass Balance Computation, Marc Nelson, K.L. White, T.S. Soerens

Technical Reports

Phosphorus levels in the Illinois River are of great interest to the people of the States of Arkansas and Oklahoma. A great deal of effort has been expended to ascertain and modify the phosphorus impacts on the river. An automatic water sampling station was installed on the Illinois River just upstream from the State line in 1996 to accurately quantify the phosphorus in the Arkansas portion of the watershed. This paper summarizes five years worth of phosphorus sampling results at that site. In addition, a simple mass balance for phosphorus in the Illinois River Watershed above the sampling station was …


Correlating Soil Test Phosphorus Losses In Runoff, D. H. Pote, T. C. Daniel, P. A. Moore Jr., D. J. Nichols, D. R. Edwards, A. N. Sharpley Jun 1994

Correlating Soil Test Phosphorus Losses In Runoff, D. H. Pote, T. C. Daniel, P. A. Moore Jr., D. J. Nichols, D. R. Edwards, A. N. Sharpley

Technical Reports

Phosphorus in agricultural runoff is often a major cause of accelerated eutrophication of lakes and streams. Previous research has indicated that the amount of dissolved P (DP) in runoff is directly related to P content of the surface soil. Decades of fertilizer application at rates exceeding those of crop uptake have elevated soil test P (STP) levels in areas of intensive crop and livestock production, making this the major source of DP loss in runoff. The objective of our experiment was to relate STP content of Captina silt loam to P concentration and loss in runoff, and determine which STP …


Focus On Phosphorus: Arkansas Water Resources Center Research Conference, Kenneth F. Steele Apr 1993

Focus On Phosphorus: Arkansas Water Resources Center Research Conference, Kenneth F. Steele

Technical Reports

No abstract provided.


Evaluation Of Nitrogen And Phosphorus Enrichment Using In Situ Enclosure Bags With Temporal Indigenous Phytoplankton Populations, Richard L. Meyer, W. Reed Green Sep 1984

Evaluation Of Nitrogen And Phosphorus Enrichment Using In Situ Enclosure Bags With Temporal Indigenous Phytoplankton Populations, Richard L. Meyer, W. Reed Green

Technical Reports

An in situ experimental procedure and protocol was developed to evaluate nitrate and phosphate enrichment using isolated indigenous phytoplankton assemblages during different seasons. Results of the comparison of the parameters-temperature, pH, alkalinity, conductivity, and dissolved oxygen between the open water and enclosed systems indicated that there was no significant influence of the physicochemical factors on the isolated biological processes. Growth responses were measured by turbidity, biomass and chlorophyll-a, the most sensitive being chlorophyll-a. Additions of nitrate and phosphate were added in known concentrations and in different magnitudes of concentration based upon ambient conditions and ratio. During the fall, phosphorus influenced …


A Study Of Phytoplankton Dynamics In Lake Fayetteville As A Means Of Assessing Water Quality, Richard L. Meyer Aug 1971

A Study Of Phytoplankton Dynamics In Lake Fayetteville As A Means Of Assessing Water Quality, Richard L. Meyer

Technical Reports

Phytoplankton community was analyzed for seasonal and vertical distribution in Lake Fayetteville. This northwest Arkansas reservoir maintains a stable water level and chemical input with a relatively constant, slow overflow. Its source is groundwater seepage through a calcareous substrate with little contribution from the limited drainage basin. Phytoplankton community development with its associations and assemblages, chlorophylls -a, -b and c, and biomass distribution are described. The seasonal cycles of the chemical parameters NH4-N, NO2-N, NO3-N, ortho-phosphate, silicon, pH, HCO3- and total-alkalinity plus oxygen are described and discussed. The physical parameters of temperature, light and climate are included. The interaction of …