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Chlorophyll-a

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Articles 1 - 19 of 19

Full-Text Articles in Physical Sciences and Mathematics

Nutrient Pollution And Chlorophyll-A As A Precursor To Harmful Algal Blooms And Cyanotoxins In Rehabilitated Machado Lake, California, Michael E. Shiang Jan 2023

Nutrient Pollution And Chlorophyll-A As A Precursor To Harmful Algal Blooms And Cyanotoxins In Rehabilitated Machado Lake, California, Michael E. Shiang

Walden Dissertations and Doctoral Studies

Algal blooms result in the formation of cyanotoxic conditions in a freshwater lake causing severe detrimental impacts to community and public health. Nitrogen, phosphorous, and ammonia stimulate the growth of phytoplankton biomass and algae, as measured by chlorophyll. This retrospective quantitative research study, grounded in the socioecological model, examined the relationship between nutrient pollutants and chlorophyll-a (Chl-a) that forecast harmful algal blooms, a precursor to cyanotoxins. A former impaired lake, Machado Lake in California, provided an ideal setting to assess relationships among nutrient indicators and Chl-a post-lake rehabilitation. Correlation and multiple regression analyses were performed to determine if a relationship …

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Nutrient Pollution And Chlorophyll-A As A Precursor To Harmful Algal Blooms And Cyanotoxins In Rehabilitated Machado Lake, California, Michael E. Shiang Jan 2023

Nutrient Pollution And Chlorophyll-A As A Precursor To Harmful Algal Blooms And Cyanotoxins In Rehabilitated Machado Lake, California, Michael E. Shiang

Walden Dissertations and Doctoral Studies

Algal blooms result in the formation of cyanotoxic conditions in a freshwater lake causing severe detrimental impacts to community and public health. Nitrogen, phosphorous, and ammonia stimulate the growth of phytoplankton biomass and algae, as measured by chlorophyll. This retrospective quantitative research study, grounded in the socioecological model, examined the relationship between nutrient pollutants and chlorophyll-a (Chl-a) that forecast harmful algal blooms, a precursor to cyanotoxins. A former impaired lake, Machado Lake in California, provided an ideal setting to assess relationships among nutrient indicators and Chl-a post-lake rehabilitation. Correlation and multiple regression analyses were performed to determine if a relationship …

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Effects Of Hydrological And Climatic Variables On Cyanobacterial Blooms In Four Large Shallow Lakes Fed By The Yangtze River, Jian Huang, Qiujin Xu, Xixi Wang, Hao Ji, Edward J. Quigley, Mohamadali Sharbatmaleki, Simeng Li, Beidou Xi, Biao Sun, Caole Li Jan 2021

Effects Of Hydrological And Climatic Variables On Cyanobacterial Blooms In Four Large Shallow Lakes Fed By The Yangtze River, Jian Huang, Qiujin Xu, Xixi Wang, Hao Ji, Edward J. Quigley, Mohamadali Sharbatmaleki, Simeng Li, Beidou Xi, Biao Sun, Caole Li

Civil & Environmental Engineering Faculty Publications

Shallow lakes, one of the most widespread water bodies in the world, are easily shifted to a new trophic state due to external interferences. Shifting hydrologic conditions and climate change can cause cyanobacterial harmful algal blooms (CyanoHABs) in shallow lakes, which pose serious threats to ecological integrity and human health. This study analyzed the effects of hydrologic and meteorological variables on cyanobacterial blooms in Yangtze-connected lakes (Lake Dongting and Poyang) and isolated lakes (Lake Chao and Tai). The results show that (i) chlorophyll-a (Chl-a) concentration tends to decrease exponentially with increasing relative lake level fluctuations (RLLF) and precipitation, but to …

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Employing Earth Observations And Artificial Intelligence To Address Key Global Environmental Challenges In Service Of The Sdgs, Wenzhao Li Dec 2019

Employing Earth Observations And Artificial Intelligence To Address Key Global Environmental Challenges In Service Of The Sdgs, Wenzhao Li

Computational and Data Sciences (PhD) Dissertations

Earth Observation (EO) data provides the capability to integrate data from multiple sources and helps to produce more relevant, frequent, and accurate information about complex processes. EO, empowered by methodologies from Artificial Intelligence (AI), supports various aspects of the UN’s Sustainable Development Goals (SDGs). This dissertation presents author’s major studies using EO to fill in knowledge gaps and develop methodologies and cloud-based applications in selected SDGs, including SDG 6 (Clean Water and Sanitation), SDG 11 (Sustainable Cities and Communities), SDG 14 (Life below Water) and SDG 15 (Life on Land). For SDG 6, the study focuses on spatiotemporal water recharge …

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The Stability Of Temperate Lakes Under The Changing Climate, Aleksey Paltsev Sep 2019

The Stability Of Temperate Lakes Under The Changing Climate, Aleksey Paltsev

Electronic Thesis and Dissertation Repository

There is a collective prediction among ecologists that climate change will enhance phytoplankton biomass in temperate lakes. Yet there is noteworthy variation in the structure and regulating functions of lakes to make this statement challengeable and, perhaps, inaccurate. To generate a common understanding on the trophic transition of lakes, I examined the interactive effects of climate change and landscape properties on phytoplankton biomass in 12,644 lakes located in relatively intact forested landscapes. Chlorophyll-a (Chl-a) concentration was used as a proxy for phytoplankton biomass. Chl-a concentration was obtained via analyzing Landsat satellite imagery data over a 28-year period (1984-2011) and using …

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Optimal Algorithms For Deriving Estimates Of Phytoplankton Biomass In Lakes From Landsat Satellite Imagery, Michael A. Dallosch Apr 2019

Optimal Algorithms For Deriving Estimates Of Phytoplankton Biomass In Lakes From Landsat Satellite Imagery, Michael A. Dallosch

Electronic Thesis and Dissertation Repository

The frequency, intensity, and geographical distribution of harmful phytoplankton blooms are on the rise globally. There is a scientific need for estimates of historical and current phytoplankton data. This research develops mathematical algorithms for accurate assessment of surface chlorophyll-a (chl-a), a proxy for phytoplankton biomass, within freshwater lakes. Landsat satellite images (4-5 TM, 7 ETM and 8 OLI) were used to create predictive models (from 1984 to 2017) for seven ecoregions (ranging from the tropics to arctic). Correlation tests for 82 algorithms were conducted to establish the best fit models (linear, exponential, logarithmic, power) for chl-a …

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Ecological Response Of Phytoplankton To The Oil Spills In The Oceans, Danling Tang, Jing Sun, Li Zhou, Sufen Wang, Ramesh P. Singh, Gang Pan Feb 2019

Ecological Response Of Phytoplankton To The Oil Spills In The Oceans, Danling Tang, Jing Sun, Li Zhou, Sufen Wang, Ramesh P. Singh, Gang Pan

Mathematics, Physics, and Computer Science Faculty Articles and Research

Oil spills in oceans have substantial influence on marine ecosystems. This study investigates 21 oil spills in the world. Analyzing Chlorophyll-a (Chl-a) from Moderate Resolution Imaging Spectroradiomerer (MODIS) data after Penglai oil spills on 4 June 2011, found a bloom with peak value of Chl-a (13.66 mg m−3) spread over an area of 800 km2 during 18–25 June 2011, and a pronounced increase in the monthly Chl-a concentration (6.40 mg m−3) on June 2012 in the Bohai Sea. Out of the 21 oil spills, 14 blooms were observed, while 11 …

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Developing Ocean Color Algorithm Using Moderate Resolution Imaging Spectroradiometer (Modis) Sensor For Shallow Coastal Water Bodies, Mohd Manzar Abbas Jun 2018

Developing Ocean Color Algorithm Using Moderate Resolution Imaging Spectroradiometer (Modis) Sensor For Shallow Coastal Water Bodies, Mohd Manzar Abbas

FIU Electronic Theses and Dissertations

This study analyses the spatial and temporal variability of chlorophyll-a in Chesapeake Bay; assesses the performance of Ocean Color 3M (OC3M) algorithm; and develops a novel algorithm to estimate chlorophyll-a for coastal shallow water. The OC3M algorithm yields an accurate estimate of chlorophyll-a concentration for deep ocean water (RMSE=0.016), but it failed to perform well in the coastal water system (RMSE=23.17) of Chesapeake Bay. A novel algorithm was developed which utilizes green and red bands of the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. The novel algorithm derived the chlorophyll-a concentration more accurately in Chesapeake Bay (RMSE=4.20) than the OC3M algorithm. …

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Applications Of Reservoir Limnology Theory And Steady-State Modeling To Eutrophication Management In Beaver Lake, Arkansas, Matthew Rich May 2018

Applications Of Reservoir Limnology Theory And Steady-State Modeling To Eutrophication Management In Beaver Lake, Arkansas, Matthew Rich

Graduate Theses and Dissertations

Reservoir limnology theory predicts that phytoplankton biomass (PB) is greatest in riverine-transition zones and least in lacustrine zones leading to an inverse pattern in water clarity. These theoretical patterns were utilized to create a statistical model of chlorophyll-a (Chl-a), an indicator of PB, and Secchi transparency (ST), an indicator of Chl-a, in Beaver Lake, Arkansas, a 12,800-ha reservoir, in order to hindcast historical conditions. Sampling for Chl-a, ST, and photic depth occurred semimonthly at 12 locations along a 78-km transect from the river inflow to the dam during the 2015 growing season. The ratio of Chl-a and ST measured at …

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An Assessment Of Atmospheric And Meteorological Factors Regulating Red Sea Phytoplankton Growth, Wenzhao Li, Hesham El-Askary, Mohamed A. Qurban, Emmanouil Proestakis, Michael J. Garay, Olga V. Kalishnikova, Vassilis Amiridis, Antonis Gkikas, Eleni Marinou, Thomas Piechota, K. P. Manikandan Apr 2018

An Assessment Of Atmospheric And Meteorological Factors Regulating Red Sea Phytoplankton Growth, Wenzhao Li, Hesham El-Askary, Mohamed A. Qurban, Emmanouil Proestakis, Michael J. Garay, Olga V. Kalishnikova, Vassilis Amiridis, Antonis Gkikas, Eleni Marinou, Thomas Piechota, K. P. Manikandan

Mathematics, Physics, and Computer Science Faculty Articles and Research

This study considers the various factors that regulate nutrients supply in the Red Sea. Multi-sensor observation and reanalysis datasets are used to examine the relationships among dust deposition, sea surface temperature (SST), and wind speed, as they may contribute to anomalous phytoplankton blooms, through time-series and correlation analyses. A positive correlation was found at 0–3 months lag between chlorophyll-a (Chl-a) anomalies and dust anomalies over the Red Sea regions. Dust deposition process was further examined with dust aerosols’ vertical distribution using satellite lidar data. Conversely, a negative correlation was found at 0–3 months lag between SST anomalies …

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Synergistic Use Of Remote Sensing And Modeling To Assess An Anomalously High Chlorophyll-A Event During Summer 2015 In The South Central Red Sea, Wenzhao Li, Hesham El-Askary, K. P. Manikandan, Mohamed A. Qurban, Michael J. Garay, Olga V. Kalishnikova Jul 2017

Synergistic Use Of Remote Sensing And Modeling To Assess An Anomalously High Chlorophyll-A Event During Summer 2015 In The South Central Red Sea, Wenzhao Li, Hesham El-Askary, K. P. Manikandan, Mohamed A. Qurban, Michael J. Garay, Olga V. Kalishnikova

Mathematics, Physics, and Computer Science Faculty Articles and Research

An anomalously high chlorophyll-a (Chl-a) event (>2 mg/m3) during June 2015 in the South Central Red Sea (17.5° to 22°N, 37° to 42°E) was observed using Moderate Resolution Imaging Spectroradiometer (MODIS) data from the Terra and Aqua satellite platforms. This differs from the low Chl-a values (<0.5 mg/m3) usually encountered over the same region during summertime. To assess this anomaly and possible causes, we used a wide range of oceanographical and meteorological datasets, including Chl-a concentrations, sea surface temperature (SST), sea surface height (SSH), mixed layer depth (MLD), ocean current velocity and aerosol optical depth (AOD) obtained from different sensors and models. Findings confirmed this anomalous behavior in the spatial domain using Hovmöller data analysis techniques, while a time series analysis addressed monthly and daily variability. Our analysis suggests that a combination of factors controlling nutrient supply contributed to the anomalous phytoplankton growth. These factors include horizontal transfer of upwelling water through eddy circulation and possible mineral fertilization from atmospheric dust deposition. Coral reefs might have provided extra nutrient supply, yet this is out of the scope of our analysis. We thought that dust deposition from a coastal dust jet event in late June, coinciding with the phytoplankton blooms in the area under investigation, might have also contributed as shown by our AOD findings. However, a lag cross correlation showed a two- month lag between strong dust outbreak and the high Chl-a anomaly. The high Chl-a concentration at the edge of the eddy emphasizes the importance of horizontal advection in fertilizing oligotrophic (nutrient poor) Red Sea waters.

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Spatiotemporal Distribution Of Eutrophication In Lake Tai As Affected By Wind, Wenhui Zhang, Qiujin Xu, Xixi Wang, Xiaozhen Hu, Cheng Wang, Yan Pang, Yanbin Hu, Yang Zhao, Xiao Zhao Jan 2017

Spatiotemporal Distribution Of Eutrophication In Lake Tai As Affected By Wind, Wenhui Zhang, Qiujin Xu, Xixi Wang, Xiaozhen Hu, Cheng Wang, Yan Pang, Yanbin Hu, Yang Zhao, Xiao Zhao

Civil & Environmental Engineering Faculty Publications

One common hypothesis is that wind can affect concentrations of nutrients (i.e., nitrogen and phosphorus) and chlorophyll-a (Chl-a) in shallow lakes. However, the tests of this hypothesis have yet to be conclusive in existing literature. The objective of this study was to use long-term data to examine how wind direction and wind speed affect the spatiotemporal variations of total nitrogen (TN), total phosphorus (TP) and Chl-a in Lake Tai, a typical shallow lake located in east China. The results indicated that the concentrations of nutrients and Chl-a tended to decrease from the northwest to the southeast of Lake Tai, with …

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Impacts To Phytoplankton After The Establishment Of Quagga Mussels In Lake Mead, Nevada, Warren Bruce Turkett May 2016

Impacts To Phytoplankton After The Establishment Of Quagga Mussels In Lake Mead, Nevada, Warren Bruce Turkett

UNLV Theses, Dissertations, Professional Papers, and Capstones

Quagga mussels (Dreissena rostriformis bugensis) are an invasive species that were discovered in Lake Mead in January of 2007, and rapidly spread throughout the lake. Quagga mussels are about the size of a fingernail, but are known to clog pipes, damage infrastructure and alter ecosystems. In large numbers, mussels can have a dramatic impact on an ecosystem by reducing the phytoplankton and potentially increasing toxin producing cyanobacteria. This research analyzed data collected from three separate basins in Lake Mead to determine if water quality characteristics that are commonly impacted by invasive mussels have changed. Transparency, chlorophyll-a, phytoplankton and zooplankton samples …

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Estimation Of Chlorophyll-A Concentration In Turbid Productive Waters Using Airborne Hyperspectral Data, Wesley J. Moses, Anatoly Gitelson, Richard L. Perk, Daniela Gurlin, Donald C. Rundquist, Bryan C. Leavitt, Tadd M. Barrow, Paul Brakhage Jan 2012

Estimation Of Chlorophyll-A Concentration In Turbid Productive Waters Using Airborne Hyperspectral Data, Wesley J. Moses, Anatoly Gitelson, Richard L. Perk, Daniela Gurlin, Donald C. Rundquist, Bryan C. Leavitt, Tadd M. Barrow, Paul Brakhage

School of Natural Resources: Faculty Publications

Algorithms based on red and near infra-red (NIR) reflectances measured using field spectrometers have been previously shown to yield accurate estimates of chlorophylla concentration in turbid productive waters, irrespective of variations in the bio-optical characteristics of water. The objective of this study was to investigate the performance of NIR-red models when applied to multi-temporal airborne reflectance data acquired by the hyperspectral sensor, Airborne Imaging Spectrometer for Applications (AISA), with non-uniform atmospheric effects across the dates of data acquisition. The results demonstrated the capability of the NIR-red models to capture the spatial distribution of chlorophyll-a in surface waters without the need …

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Operational Meris-Based Nir-Red Algorithms For Estimating Chlorophyll-A Concentrations In Coastal Waters — The Azov Sea Case Study, Wesley J. Moses, Anatoly A. Gitelson, Sergey Berdnikov, Vladislav Saprygin, Vasily Povazhnyi Jan 2012

Operational Meris-Based Nir-Red Algorithms For Estimating Chlorophyll-A Concentrations In Coastal Waters — The Azov Sea Case Study, Wesley J. Moses, Anatoly A. Gitelson, Sergey Berdnikov, Vladislav Saprygin, Vasily Povazhnyi

School of Natural Resources: Faculty Publications

We present here results that strongly support the use of MERIS-based NIR-red algorithms as standard tools for estimating chlorophyll-a (chl-a) concentration in turbid productive waters. The study was carried out as one of the steps in testing the potential of the universal applicability of previously developed NIR-red algorithms, which were earlier calibrated using a limited set of MERIS imagery and in situ data from the Azov Sea and the Taganrog Bay, Russia, and data that were synthetically generated using a radiative transfer model. We used an extensive set of MERIS imagery and in situ data collected over …

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Satellite-Based Estimation Of Chlorophyll-A Concentration In Turbid Productive Waters, Wesley Moses Dec 2009

Satellite-Based Estimation Of Chlorophyll-A Concentration In Turbid Productive Waters, Wesley Moses

School of Natural Resources: Dissertations, Theses, and Student Research

Inland, coastal, and estuarine waters, which are often turbid and biologically productive, play a crucial role in maintaining global bio-diversity and are of immense value to aquatic life as well as human-beings. Concentration of chlorophyll-a (chl-a) is a key indicator of the trophic status of these waters, which should be regularly monitored to ensure that their ecological balance is not disturbed. Remote sensing is a powerful tool for this.

Due to the optical complexity of turbid productive waters, standard algorithms that use blue and green reflectances are unreliable for estimating chl-a concentration. Algorithms based on red and near-infrared (NIR) reflectances …

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Estimation Of Chlorophyll-A Concentration In Case Ii Waters Using Modis And Meris Data—Successes And Challenges, Wesley Moses, Anatoly Gitelson, Sergey Berdnikov, Vasiliy Povazhnyi Oct 2009

Estimation Of Chlorophyll-A Concentration In Case Ii Waters Using Modis And Meris Data—Successes And Challenges, Wesley Moses, Anatoly Gitelson, Sergey Berdnikov, Vasiliy Povazhnyi

School of Natural Resources: Faculty Publications

We present and discuss here the results of our work using MODIS (moderate resolution imaging spectroradiometer) and MERIS (medium resolution imaging spectrometer) satellite data to estimate the concentration of chlorophyll-a (chl-a) in reservoirs of the Dnieper River and the Sea of Azov, which are typical case II waters, i.e., turbid and productive. Our objective was to test the potential of satellite remote sensing as a tool for near-real-time monitoring of chl-a distribution in these water bodies. We tested the performance of a recently developed three-band model, and its special case, a two-band model, which use the reflectance at red and …

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Wavelength-Specific Fluorescence Coefficients For Simulating Hyperspectral Reflectance Signatures Of Water, Charles R. Bostater, Jan Rebman Dec 1999

Wavelength-Specific Fluorescence Coefficients For Simulating Hyperspectral Reflectance Signatures Of Water, Charles R. Bostater, Jan Rebman

Ocean Engineering and Marine Sciences Faculty Publications

A model1'2 which describes the transfer of irradiant light in water is used to predict the fluorescence response ofthe water surface reflectance under solar induced or an artificial light source such as a laser. Formulations for the estimation of wavelength dependent fluorescent coefficients. The techniques allows the description ofa fluorescence reflectance response in deep and shallow waters with various bottom reflectance signatures such as submerged vegetation, corals and sand. Recent advances in the model are presented for obtaining wavelength dependent fluorescence spectrum responses from the solutions of the two flow equations following the procedures developed by Bostater1'2'3. Synthetic or modeled …

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Application Of A Flow-Through Absorption Tube For Remotely Estimating Water-Quality Parameters, Charles Bostater, Melissa Keller, Manuel Gimond Jan 1997

Application Of A Flow-Through Absorption Tube For Remotely Estimating Water-Quality Parameters, Charles Bostater, Melissa Keller, Manuel Gimond

Ocean Engineering and Marine Sciences Faculty Publications

A flow through absorption tube is described and applied. The tube is similar in concept to a 50 cm pathlength cylindrical cuvette described previously by Bostater and Gimond.' The new absorption tube allows for continuous, underway measurements of water absorption signatures. Water is allowed to flow through the tube, and in this way the spectral change or track ofabsorption can be measured as a function oftime or space when operated from a stationary or moving platform. Data gathered from various environments ranging from very turbid to clear water is analyzed and described. Concentrations of chlorophyll-a, suspended matter, and dissolved organic …

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