oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Advances on Satellite Remote Sensing Technique for Algal Blooms Detection
赤潮卫星遥感监测与应用研究进展

MA Jin-feng,ZHAN Hai-gang,CHEN Chu-qun,TANG Shi-lin,
马金峰
,詹海刚,陈楚群,唐世林

遥感技术与应用 , 2008,
Abstract: Remotely-sensed monitoring for algal blooms is one of the important subjects of remote sensing application.With the development of almost 30 years,many algorithms for detection of algal blooms based on satellite data were developed by scholars both at home and abroad.The history of satellite remote sensing detection for algal blooms is reviewed,the remote sensing monitoring algorithms of several sensors are summarized,and their performance and application range are analyzed.Finally,the challenge of remotely-sensed monitoring for algal blooms is discussed,and the prospect of remotely-sensed monitoring for algal blooms is proposed.
Satellite Remote Sensing of Harmful Algal Blooms (HABs) and a Potential Synthesized Framework  [PDF]
Li Shen,Huiping Xu,Xulin Guo
Sensors , 2012, DOI: 10.3390/s120607778
Abstract: Harmful algal blooms (HABs) are severe ecological disasters threatening aquatic systems throughout the World, which necessitate scientific efforts in detecting and monitoring them. Compared with traditional in situ point observations, satellite remote sensing is considered as a promising technique for studying HABs due to its advantages of large-scale, real-time, and long-term monitoring. The present review summarizes the suitability of current satellite data sources and different algorithms for detecting HABs. It also discusses the spatial scale issue of HABs. Based on the major problems identified from previous literature, including the unsystematic understanding of HABs, the insufficient incorporation of satellite remote sensing, and a lack of multiple oceanographic explanations of the mechanisms causing HABs, this review also attempts to provide a comprehensive understanding of the complicated mechanism of HABs impacted by multiple oceanographic factors. A potential synthesized framework can be established by combining multiple accessible satellite remote sensing approaches including visual interpretation, spectra analysis, parameters retrieval and spatial-temporal pattern analysis. This framework aims to lead to a systematic and comprehensive monitoring of HABs based on satellite remote sensing from multiple oceanographic perspectives.
Development of Sub-Seasonal Remote Sensing Chlorophyll-A Detection Models  [PDF]
Carly Hansen, Nathan Swain, Kate Munson, Zola Adjei, Gustavious Paul Williams, Wood Miller
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.412A2003
Abstract:

Remote sensing techniques are proven methods for quantifying chlorophyll-a levels by inference algal concentrations in reservoirs. One traditional method is to use Landsat imagery and field data from a limited time period to develop a model for a reservoir which relates reflectance in various bands to measured algal (or chlorophyll-a) concentrations and use that model and associated imagery to determine spatial algal concentrations in the reservoir. In this work, we extend these techniques to use historical Landsat data over long time periods to develop seasonal models that will more accurately describe the conditions throughout the growing season. Previous work at Deer Creek included the development of a chlorophyll-a model using data from the months of August to September. This model did not account for seasonal variation and algal succession, which affects the relationship between measured reflectance and algal concentration. Early summer algal blooms are dominated by diatoms (yellow-brown), while the algae vary from chlorophyta (green) in the mid-summer to cyanobacteria (blue-green) in late summer months. This study presents and explores the development and use of seasonal algorithms based on reflective characteristics of various algal communities to create a more accurate model for the reservoir. This study uses water quality data collected over a 20-year period during non-ice conditions along with associated Landsat data. As the field measurements were not taken to support remote sensing measurements, this study evaluates the use of historical data to support remote sensing analysis. It is assumed that reservoir conditions do not change rapidly, the field data can be used to develop correlations with satellite imagery taken within a day of the field measurements, and the seasonal algal communities have different reflective properties (or colors). We present statistical analysis that shows the seasonal algorithms better fit the data than the non-seasonal model and the traditional model calibrated with late-season data. We recommend the use of sub-seasonal algorithms to more accurately model and predict water quality throughout the growing season.

Long-Term Application of Remote Sensing Chlorophyll Detection Models: Jordanelle Reservoir Case Study  [PDF]
Carly Hyatt Hansen, Gustavious P. Williams, Zola Adjei
Natural Resources (NR) , 2015, DOI: 10.4236/nr.2015.62011
Abstract: Algae blooms pose a threat to water quality by depleting oxygen during decomposition and also cause other issues with water quality and water use. Algae biomass is traditional monitored through field samples analyzed for chlorophyll-a, a pigment present in all algae. Field sampling can be time- and cost-intensive, especially in areas that are difficult to access and provides only limited spatial coverage. Estimations of algal biomass based on remote sensing data have been explored over the past two decades as a supplement to information obtained from limited field samples. We use Landsat data to develop and demonstrate seasonal remote sensing models, a relatively recent method, to evaluate spatial and temporal algae distributions for the Jordanelle Reservoir, located in north-central Utah. Remote sensing of chlorophyll as a monitoring and analysis method can provide a more spatially complete representation of algae distribution and biomass; information that is difficult to obtain using point samples.
Spatial-Temporal Variations of Turbidity and Ocean Current Velocity of the Ariake Sea Area, Kyushu, Japan Through Regression Analysis with Remote Sensing Satellite Data  [PDF]
Kohei Arai,Yuichi Sarusawa
International Journal of Advanced Computer Sciences and Applications , 2013,
Abstract: Regression analysis based method for turbidity and ocean current velocity estimation with remote sensing satellite data is proposed. Through regressive analysis with MODIS data and measured data of turbidity and ocean current velocity, regressive equation which allows estimation of turbidity and ocean current velocity is obtained. With the regressive equation as well as long term MODIS data, turbidity and ocean current velocity trends in Ariake Sea area are clarified. It is also confirmed that the negative correlation between ocean current velocity and turbidity.
Is Occurrence of Harmful Algal Blooms in the Exclusive Economic Zone of India on the Rise?  [PDF]
K. B. Padmakumar,N. R. Menon,V. N. Sanjeevan
International Journal of Oceanography , 2012, DOI: 10.1155/2012/263946
Abstract: Occurrence, increase in frequency, intensity and spatial coverage of harmful algal blooms during the past decade in the EEZ of India are documented here. Eighty algal blooms were recorded during the period 1998–2010. Of the eighty algal blooms, 31 blooms were formed by dinoflagellates, 27 by cyanobacteria, and 18 by diatoms. Three raphidophyte and one haptophyte blooms were also observed. Potentially toxic microalgae recorded from the Indian waters were Alexandrium spp., Gymnodinium spp. Dinophysis spp., Coolia monotis, Prorocentrum lima, and Pseudo-nitzschia spp. Examination of available data from the literature during the last hundred years and in situ observations during 1998–2010 indicates clear-cut increase in the occurrence of HABs in the Indian EEZ.
Prevention of Harmful Algal Blooms by Control of Growth Parameters  [PDF]
Tai-Jin Kim
Advances in Bioscience and Biotechnology (ABB) , 2018, DOI: 10.4236/abb.2018.911043
Abstract: Harmful Algal Blooms (HAB) were investigated to prevent the outbreak of HAB in both freshwater and seawater. Parameters inducing HAB were volcanic eruption, sunlight, aeolian dust, environmental factors (current, pH, dissolved oxygen, food web, turbulence, growth phase), enzyme, iron, nutrients (carbon, nitrogen, phosphorus, sulfur, silicon, minerals) while the critical growth parameter for the outbreak of HAB was iron (Fe). HAB development was halted in freshwater and seawater due to the sulfur compounds (H2S, sulfates) inducing the deficiency of the dissolved Fe in the water. The atomic ratio of N/P is commonly known to be 16/1 in freshwater and 176/1 in seawater for HAB. Therefore, nitrogen can be a relatively limiting factor in seawater while phosphorus in freshwater. HAB could be prevented by control of growth parameters such as pH, temperature, sunlight, turbulence, nitrogen, phosphorus, iron, and sulfur compounds prior to reaching the early exponential phase of algal growth.
Is Occurrence of Harmful Algal Blooms in the Exclusive Economic Zone of India on the Rise?  [PDF]
K. B. Padmakumar,N. R. Menon,V. N. Sanjeevan
International Journal of Oceanography , 2012, DOI: 10.1155/2012/263946
Abstract: Occurrence, increase in frequency, intensity and spatial coverage of harmful algal blooms during the past decade in the EEZ of India are documented here. Eighty algal blooms were recorded during the period 1998–2010. Of the eighty algal blooms, 31 blooms were formed by dinoflagellates, 27 by cyanobacteria, and 18 by diatoms. Three raphidophyte and one haptophyte blooms were also observed. Potentially toxic microalgae recorded from the Indian waters were Alexandrium spp., Gymnodinium spp. Dinophysis spp., Coolia monotis, Prorocentrum lima, and Pseudo-nitzschia spp. Examination of available data from the literature during the last hundred years and in situ observations during 1998–2010 indicates clear-cut increase in the occurrence of HABs in the Indian EEZ. 1. Introduction The International Council for the Exploration of the Seas [1] has defined phytoplankton blooms as, those, which are noticeable, particularly to general public, directly or indirectly through their effects such as visible discolouration of the waters, foam production, and fish or invertebrate mortality or toxicity to humans. Among around 5000 species of marine phytoplankton, around 300 species including diatoms, dinoflagellate, raphidophytes, prymnesiophytes, cyanophytes, and silicoflagellates can at times cause algal blooms. Only a few dozen of these species have the ability to produce potent toxins. Harmful Algal Blooms (HABs) are global phenomenon, reported from over 30 countries including India. Number of HABs, economic losses from them, the types of resources affected, and number of toxins and toxic species have also increased dramatically in recent years [2–4]. The first recorded observation on algal blooms in Indian waters is by Hornell in 1908 [5]. He witnessed massive fish mortality, largely of sardines floating on the dark yellow coloured water that contained plankton. In 1916, he found Euglena and Noctiluca species to be responsible for such episodes. Subrahmanyan [6] identified this organism as Hornellia marina, and later in 1982 Hara and Chihara [7] reclassified this as the raphidophyte Chattonella marina. Since then, there have been several reports on various algal blooms dominated by blooms of Noctiluca scintillans (= N. miliaris) and Trichodesmium spp. from the EEZ of India. Episodic observations on algal blooms were reported from 1917 onwards. First record of Paralytic Shellfish Poisoning (PSP) was during 1981 from coastal Tamilnadu, Karnataka, and Maharashtra [8]. In 1981, PSP resulted in death of 3 persons and hospitalization of 85 people due to consumption of
Biological control of Microcystis dominated harmful algal blooms
RJ Gumbo, G Ross, ET Cloete
African Journal of Biotechnology , 2008,
Abstract: Freshwater resources are now threatened by the presence and increase of harmful algal blooms (HAB) all over the world. The HABs are sometimes a direct result of anthropogenic pollution entering water bodies, such as partially treated nutrient-rich effluents and the leaching of fertilisers and animal wastes. The impact of HABs on aquatic ecosystems and water resources, as well as their human health implications are well documented. Countermeasures have been proposed and implemented to manage HABs with varying levels of success. The use of copper algicides, though effective in managing HABs, often results in negative impacts such as copper toxicity and release of microcystins into surrounding water after cyanobacterial lysis. Biological control of HABs presents a possible solution. Predatory bacteria that have been isolated as potential biological control agents include members of the Bacteroides-Cytophaga-Flavobacterium, ranging from Bacillus spp. to Flexibacter spp., Cytophaga and Myxobacteria. Various mechanisms of predation have been proposed, including; physical contact between prey and predator, release of extracellular substances, entrapment of prey by the predator followed by antibiosis and endoparasitism or ectoparasitism of the host by the predator. Despite an increasing amount of work being done in this field, research is usually limited to laboratory cultures; assessment of microbial control agents is seldom extrapolated to field conditions.
Longitudinal Hydrodynamic Characteristics in Reservoir Tributary Embayments and Effects on Algal Blooms  [PDF]
Huichao Dai, Jingqiao Mao, Dingguo Jiang, Lingling Wang
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0068186
Abstract: Three Gorges Reservoir (TGR) is one of the largest man-made lakes in the world. Since the impoundment in 2003, however, algal blooms have been often observed in the tributary embayments. To control the algal blooms, a thorough understanding of the hydrodynamics (e.g., flow regime, velocity gradient, and velocity magnitude and direction) in the tributary embayments is particularly important. Using a calibrated three-dimensional hydrodynamic model, we carried out a hydrodynamic analysis of a typical tributary embayment (i.e., Xiangxi Bay) with emphasis on the longitudinal patterns. The results show distinct longitudinal gradients of hydrodynamics in the study area, which can be generally characterized as four zones: riverine, intermediate, lacustrine, and mainstream influenced zones. Compared with the typical longitudinal zonation for a pure reservoir, there is an additional mainstream influenced zone near the mouth due to the strong effects of TGR mainstream. The blooms are prone to occur in the intermediate and lacustrine zones; however, the hydrodynamic conditions of riverine and mainstream influence zones are not propitious for the formation of algal blooms. This finding helps to diagnose the sensitive areas for algal bloom occurrence.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.