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Sample records for defining chlorophyll-a reference

  1. Defining Chlorophyll-a Reference Conditions in European Lakes

    PubMed Central

    Alves, Maria Helena; Argillier, Christine; van den Berg, Marcel; Buzzi, Fabio; Hoehn, Eberhard; de Hoyos, Caridad; Karottki, Ivan; Laplace-Treyture, Christophe; Solheim, Anne Lyche; Ortiz-Casas, José; Ott, Ingmar; Phillips, Geoff; Pilke, Ansa; Pádua, João; Remec-Rekar, Spela; Riedmüller, Ursula; Schaumburg, Jochen; Serrano, Maria Luisa; Soszka, Hanna; Tierney, Deirdre; Urbanič, Gorazd; Wolfram, Georg

    2010-01-01

    The concept of “reference conditions” describes the benchmark against which current conditions are compared when assessing the status of water bodies. In this paper we focus on the establishment of reference conditions for European lakes according to a phytoplankton biomass indicator—the concentration of chlorophyll-a. A mostly spatial approach (selection of existing lakes with no or minor human impact) was used to set the reference conditions for chlorophyll-a values, supplemented by historical data, paleolimnological investigations and modelling. The work resulted in definition of reference conditions and the boundary between “high” and “good” status for 15 main lake types and five ecoregions of Europe: Alpine, Atlantic, Central/Baltic, Mediterranean, and Northern. Additionally, empirical models were developed for estimating site-specific reference chlorophyll-a concentrations from a set of potential predictor variables. The results were recently formulated into the EU legislation, marking the first attempt in international water policy to move from chemical quality standards to ecological quality targets. PMID:20401659

  2. The celestial reference frame defined by VLBI

    NASA Technical Reports Server (NTRS)

    Ma, C.; Shaffer, D. B.

    1988-01-01

    VLBI currently produces the most accurate positions of celestial objects. From 1979 to 1987, 114 extragalactic radio sources have been observed with dual-frequency Mark III VLBI as part of the NASA Crustal Dynamics Project and the NGS POLARIS/IRIS program. The formal statistical errors of conventional celestial coordinates are as small as 0.3 milliarcseconds. The fundamental quantity measured by VLBI is the arc length between radio sources. Thus, it is suggested that VLBI be used to establish a coordinate reference frame based solely on radio positions, and that this system not necessarily be coupled to right ascension and declination.

  3. Marine chlorophyll a analysis

    NASA Technical Reports Server (NTRS)

    Johnson, R. W.

    1979-01-01

    Quantitative distribution maps of chlorophyll a and other important environmental parameters of coastal zones are prepared by regression analysis of sea-truth data and data collected by aircraft multispectral scanners.

  4. Approaches to defining reference regimes for river restoration planning

    NASA Astrophysics Data System (ADS)

    Beechie, T. J.

    2014-12-01

    Reference conditions or reference regimes can be defined using three general approaches, historical analysis, contemporary reference sites, and theoretical or empirical models. For large features (e.g., floodplain channels and ponds) historical data and maps are generally reliable. For smaller features (e.g., pools and riffles in small tributaries), field data from contemporary reference sites are a reasonable surrogate for historical data. Models are generally used for features that have no historical information or present day reference sites (e.g., beaver pond habitat). Each of these approaches contributes to a watershed-wide understanding of current biophysical conditions relative to potential conditions, which helps create not only a guiding vision for restoration, but also helps quantify and locate the largest or most important restoration opportunities. Common uses of geomorphic and biological reference conditions include identifying key areas for habitat protection or restoration, and informing the choice of restoration targets. Examples of use of each of these three approaches to define reference regimes in western USA illustrate how historical information and current research highlight key restoration opportunities, focus restoration effort in areas that can produce the largest ecological benefit, and contribute to estimating restoration potential and assessing likelihood of achieving restoration goals.

  5. Selecting objectively defined reference sites for stream bioassessment programs.

    PubMed

    Yates, Adam Gordon; Bailey, Robert C

    2010-11-01

    Our study develops and demonstrates an objective method for selecting reference sites for the assessment of ecological condition in freshwater ecosystems. The method uses widely available GIS data to group potential sites based on their natural environments. It then establishes the degree and types of human activities each site is exposed to prior to scoring the sites in each group by the relative amount of human activity present. Finally, the sites in each group with the least amount of human activity are categorized as reference sites, with the boundary between reference and test sites defined to maximize the distinctiveness of the two categories with respect to human activity. Application of this technique for the purpose of identifying headwater reference basins in rural areas of southwestern Ontario resulted in the classification of basins into six natural groups based on the dominant texture of the surface geology. Development of a human activity gradient indicated that basins varied according to the amount of exposure to agricultural activities with most basins having at least moderate exposure. Establishment of the reference test boundary indicated that the selected reference basins exhibited substantively lower extents of agricultural activity than test sites for most groups. Because this method uses only widely available GIS data, it enables rapid and cost-effective identification of candidate reference sites, even for large, remote, and understudied regions. PMID:19902368

  6. Defining laboratory reference values and decision limits: populations, intervals, and interpretations

    PubMed Central

    Boyd, James C.

    2010-01-01

    This article provides a brief overview of various approaches that may be utilized for the analysis of human semen test results. Reference intervals are the most widely used tool for the interpretation of clinical laboratory results. Reference interval development has classically relied on concepts elaborated by the International Federation of Clinical Chemistry Expert Panel on Reference Values during the 1980s. These guidelines involve obtaining and classifying samples from a healthy population of at least 120 individuals and then identifying the outermost 5% of observations to use in defining limits for two-sided or one-sided reference intervals. More recently, decision limits based on epidemiological outcome analysis have also been introduced to aid in test interpretation. The reference population must be carefully defined on the basis of the intended clinical use of the underlying test. To determine appropriate reference intervals for use in male fertility assessment, a reference population of men with documented time to pregnancy of < 12 months would be most suitable. However, for epidemiological assessment of semen testing results, a reference population made up of unselected healthy men would be preferred. Although reference and decision limits derived for individual semen analysis test results will undoubtedly be the interpretational tools of choice in the near future, in the long term, multivariate methods for the interpretation of semen analysis alone or in combination with information from the female partner seem to represent better means for assessing the likelihood of achieving a successful pregnancy in a subfertile couple. PMID:20111086

  7. Defining reference levels for intra-operative radiation exposure in orthopaedic trauma: A retrospective multicentre study.

    PubMed

    Hardman, J; Elvey, M; Shah, N; Simson, N; Patel, S; Anakwe, R

    2015-12-01

    There is currently limited data to define reference levels for the use of ionising radiation in orthopaedic trauma surgery. In this multicentre study, we utilise methodology employed by the Health Protection Agency in establishing reference levels for diagnostic investigations in order to define analogous levels for common and reproducible orthopaedic trauma procedures. Four hundred ninety-five procedures were identified across four Greater London hospitals over a 1-year period. Exposure was defined in terms of both time and dose area product (DAP). Third quartile mean values for either parameter were used to define reference levels. Variations both between centres and grades of lead surgeon were analysed as secondary outcomes. Reference levels; dynamic hip screw (DHS) 1.9225000 Gycm(2)/70.50 s, intramedullary (IM) femoral nail 1.5837500 Gycm(2)/126.00 s, open reduction internal fixation (ORIF) clavicle 0.2042500 Gycm(2)/21.50 s, ORIF lateral malleolus 0.32250500 Gycm(2)/35.00 s, ORIF distal radius 0.1300000 Gycm(2)/56.00 s. Grade of surgeon did not influence exposure in dynamic hip screw, and was inversely related to exposure in intramedullary femoral nails. Less variation was observed with exposure time than with DAP. This study provides the most comprehensive reference to guide fluoroscopy use in orthopaedic trauma to date, and is of value both at the point of delivery and for audit of local practice. PMID:26604035

  8. Defining Top-of-Atmosphere Flux Reference Level for Earth Radiation Budget Studies

    NASA Technical Reports Server (NTRS)

    Loeb, N. G.; Kato, S.; Wielicki, B. A.

    2002-01-01

    To estimate the earth's radiation budget at the top of the atmosphere (TOA) from satellite-measured radiances, it is necessary to account for the finite geometry of the earth and recognize that the earth is a solid body surrounded by a translucent atmosphere of finite thickness that attenuates solar radiation differently at different heights. As a result, in order to account for all of the reflected solar and emitted thermal radiation from the planet by direct integration of satellite-measured radiances, the measurement viewing geometry must be defined at a reference level well above the earth s surface (e.g., 100 km). This ensures that all radiation contributions, including radiation escaping the planet along slant paths above the earth s tangent point, are accounted for. By using a field-of- view (FOV) reference level that is too low (such as the surface reference level), TOA fluxes for most scene types are systematically underestimated by 1-2 W/sq m. In addition, since TOA flux represents a flow of radiant energy per unit area, and varies with distance from the earth according to the inverse-square law, a reference level is also needed to define satellite-based TOA fluxes. From theoretical radiative transfer calculations using a model that accounts for spherical geometry, the optimal reference level for defining TOA fluxes in radiation budget studies for the earth is estimated to be approximately 20 km. At this reference level, there is no need to explicitly account for horizontal transmission of solar radiation through the atmosphere in the earth radiation budget calculation. In this context, therefore, the 20-km reference level corresponds to the effective radiative top of atmosphere for the planet. Although the optimal flux reference level depends slightly on scene type due to differences in effective transmission of solar radiation with cloud height, the difference in flux caused by neglecting the scene-type dependence is less than 0.1%. If an inappropriate

  9. Hematological and biochemical parameters in apparently healthy Indian population: defining reference intervals.

    PubMed

    Sairam, Shrilekha; Domalapalli, Suhasini; Muthu, Sundaram; Swaminathan, Jayanthi; Ramesh, Vivek A; Sekhar, Lalitha; Pandeya, Palak; Balasubramaniam, Udhaya

    2014-07-01

    Clinical reference intervals among Indian population are poorly defined. Therefore, there is an urgent need to establish local clinical laboratory reference intervals for healthy Indian population. The present study aimed to identify the 95 % reference interval for hematological and biochemical parameters in apparently healthy Indian population. We undertook a multicentric cross-sectional study conducted at Apollo Hospitals Educational and Research Foundation across India. Of which 10,665 reference individuals identified as healthy by physicians. The 95 % of the reference distribution was estimated using 2.5th and 97.5th percentile reference limits. The 95 % reference intervals for hemoglobin (Males: 12.3-17 g/dL; Females: 9.9-14.3 g/dL), platelet count (Males: 1.3-3.8; Females: 1.3-4.2 Lakhs/µL), erythrocyte sedimentation rate (Males: 2-22; Females: 4-55 mm/h), serum uric acid in males: 3.5-8.2 mg/dL, gamma glutamyl transferase (Males: 13-61 U/L), fasting blood glucose (Males: 78-110 mg/dL), total cholesterol (Males: 115-254 mg/dL), low density lipoprotein (Males: 60-176 mg/dL) and triglycerides (Males: 55-267 mg/dL, Females: 52-207 mg/dL) were different from currently used reference values. Additionally need for gender based partitioning were observed for triglycerides and gamma glutamyl transferase. The observed findings are of clinical significance and it needs to be validated with additional community based studies. PMID:24966476

  10. Similar prevalence of vertebral fractures despite different approaches to define reference data.

    PubMed

    Szulc, P; Munoz, F; Marchand, F; Sornay-Rendu, E; Delmas, P D

    2003-04-01

    Morphometric detection of vertebral fractures requires the use of reference normal values. In previous studies, normal values were obtained in young healthy adults or in adults of various ages in whom abnormal radiographs were excluded using trimming algorithms. We established four sets of normal values defined according to different approaches. We used a group of 102 young healthy women with normal spine radiographs and a population-based cohort of 260 women 51 to 85 years old (EVOS study) to select those with normal spine radiographs based on the semiquantitative method of Genant, the trimming algorithm defined by Melton, and the trimming algorithm defined by Black. Using the four sets of reference data, we applied two diagnostic criteria, the mean - 3SD and the 0.85 x mean to detect prevalent vertebral fractures in two groups of women: the population-based cohort of 260 women recruited for the EVOS study and 176 osteoporotic women 54 to 88 years old with at least one vertebral fracture. In the population-based cohort, the number of vertebral fractures varied from 53 to 57 for the 0.85 x mean cutoff and from 93 to 115 for the mean - 3SD cutoff. In the osteoporotic women, the number of vertebral fractures varied from 255 to 273 for the 0.85 x mean cutoff and from 372 to 404 for the mean - 3SD cutoff. In both groups, the number of vertebral fractures detected with the 0.85 x mean cutoff was close to the number detected by the semiquantitative method of Genant, which does not require a reference population. For the 0.85 x mean cutoff, agreement of diagnosis using different reference values was excellent (kappa = 0.96-0.99). For the mean - 3SD cutoff, agreement of vertebral fracture detection based on the four reference sets was good (kappa = 0.79-0.93). Agreement of diagnosis was lower when two cutoffs were compared using the same set of reference values (kappa = 0.60-0.81). In conclusion, reference data derived using different approaches give similar rates of

  11. Defining biophysical reference conditions for dynamics river systems: an Alaskan example

    NASA Astrophysics Data System (ADS)

    Pess, G. R.

    2008-12-01

    Defining reference conditions for dynamic river ecosystems is difficult for two reasons. First long-term, persistent anthropogenic influences such as land development, harvest of biological resources, and invasive species have resulted in degraded, reduced, and simplified ecological communities and associated habitats. Second, river systems that have not been altered through human disturbance rarely have a long-term dataset on ecological conditions. However there are exceptions which can help us define the dynamic nature of river ecosystems. One large-scale exception is the Wood River system in Bristol Bay, Alaska, where habitat and salmon populations have not been altered by anthropogenic influences such as land development, hatchery production, and invasive species. In addition, the one major anthropogenic disturbance, salmon (Oncorhynchus spp.) harvest, has been quantified and regulated since its inception. First, we examined the variation in watershed and stream habitat characteristics across the Wood River system. We then compared these stream habitat characteristics with data that was collected in the 1950s. Lastly, we examined the correlation between pink (Oncorhynchus gorbuscha), chum (O. keta), and Chinook (O. tshawytscha), and sockeye salmon (O. nerka), and habitat characteristics in the Wood River system using four decades of data on salmon. We found that specific habitat attributes such as stream channel wetted width, depth, cover type, and the proportion of spawnable area were similar to data collected in the 1950s. Greater stream habitat variation occurred among streams than over time. Salmon occurrence and abundance, however was more temporal and spatially variable. The occurrence of pink and chum salmon increased from the 1970's to the present in the Wood River system, while sockeye abundance has fluctuated with changes in ocean conditions. Pink, Chinook and chum salmon ranged from non-existent to episodic to abundantly perennial, while sockeye

  12. A generalized complementary relationship between actual and potential evaporation defined by a reference surface temperature

    NASA Astrophysics Data System (ADS)

    Aminzadeh, Milad; Roderick, Michael L.; Or, Dani

    2016-01-01

    The definition of potential evaporation remains widely debated despite its centrality for hydrologic and climatic models. We employed an analytical pore-scale representation of evaporation from terrestrial surfaces to define potential evaporation using a hypothetical steady state reference temperature that is common to both air and evaporating surface. The feedback between drying land surfaces and overlaying air properties, central in the Bouchet (1963) complementary relationship, is implicitly incorporated in the hypothetical steady state where the sensible heat flux vanishes and the available energy is consumed by evaporation. Evaporation rates predicted based on the steady state reference temperature hypothesis were in good agreement with class A pan evaporation measurements suggesting that evaporation from pans occurs with negligible sensible heat flux. The model facilitates a new generalization of the asymmetric complementary relationship with the asymmetry parameter b analytically predicted for a wide range of meteorological conditions with initial tests yielding good agreement between measured and predicted actual evaporation.

  13. Defining suitable reference genes for RT-qPCR analysis on intestinal epithelial cells.

    PubMed

    Sirakov, Maria; Borra, Marco; Cambuli, Francesca Maria; Plateroti, Michelina

    2013-07-01

    The study of the mammalian intestinal epithelium concerns several aspects of cellular and molecular biology. In fact, most of these studies aim to define molecular components or mechanisms related with the control of stemness and the balance between cell proliferation and differentiation in physiopathological conditions. It is worth mentioning that real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR) approaches are commonly used, but only a few studies are available regarding suitable reference genes to normalize gene expression data. The present study was designed to validate potential reference genes in freshly isolated proliferating or differentiated epithelial cells from the mouse intestine. We also extended our analysis to the IEC6 intestinal epithelial cells, as a promising model to study intestinal physiopathology in vitro. The stability of six potential reference genes (Hprt1, Ppia, Gapdh, Rplp0, Ppib, and Vil1) has been tested both in epithelial cells isolated from the mouse intestine and in the IEC6 cell line. The software programs-geNorm and Normfinder-were used to obtain an estimation of the expression stability of each gene and, by comparing the results, to identify the most suitable genes for RT-qPCR data normalization. These multiple approaches allowed us to select different suitable reference genes for the correct quantification of mRNAs depending on the differentiated or proliferative nature of the cells. PMID:23292893

  14. Structure and expression of a pea nuclear gene encoding a chlorophyll a/b-binding polypeptide

    SciTech Connect

    Cashmore, A.R.

    1984-05-01

    A nuclear gene AB80 has been isolated from a phage lambda Charon 4 library of pea DNA. The sequence of the gene has been determined and it has been shown to contain an interrupted reading frame of 269 amino acids, corresponding to a precursor to a constituent polypeptide of the light-harvesting chlorophyll a/b-protein complex. Primer extension and S1 nuclease studies defined a cap site for AB80. The first methionine codon 3' from this site is 69 nucleotides away and is the initiating codon of the open reading frame. A TATA sequence occurs 31 nucleotides 5' from the cap site. A second TATA sequence is found 7 nucleotides on the 5' side of the initiating methionine codon and the sequences surrounding this TATA sequence are strikingly similar to those surrounding the first TATA sequence. The mature polypeptide encoded by AB80 differs by 5 amino acids from the polypeptide corresponding to a previously characterized cDNA sequence pAB96. This result is indicative of heterogeneity within the constituent polypeptides of the light-harvesting chlorophyll a/b-protein complex. The sequence Arg-Lys-Ser-Ala-Thr-Thr-Lys-Lys occurs at, or near, the NH/sub 2/-terminus of the mature polypeptide encoded by AB80. This basic peptide is of interest because of its apparent involvement in changes in excitation-energy distribution in chloroplast membranes. Some general similarities, but no extensive sequence homology, is found on comparing the transit sequence for the precursor to the chlorophyll a/b-binding polypeptide with the transit sequences previously determined for the precursors to the small subunit of ribulose-1,5-bisphosphate carboxylase. 40 references, 3 figures.

  15. Analytical Complementary Relationship Between Actual and Potential Evaporation Defined by Steady State Reference Surface Temperature

    NASA Astrophysics Data System (ADS)

    Or, D.; Aminzadeh, M.; Roderick, M. L.

    2015-12-01

    The definition of potential evaporation remains widely debated despite its centrality for hydrologic and climatic models. We employed an analytical pore-scale representation of evaporation from porous surfaces to define potential evaporation using a hypothetical steady-state reference temperature for air and evaporating surface. The feedback between drying land surfaces and overlaying air properties is implicitly incorporated in the hypothetical steady-state where the sensible heat flux vanishes and available energy is consumed by evaporation. Potential evaporation based on steady-state surface temperature was in surprisingly good agreement with class A pan evaporation measurements suggesting that pan evaporation occurs with negligible sensible heat flux. The model facilitates a new analytical generalization of the asymmetric complementary relationship across a wide range of meteorological conditions with good agreement between measured and predicted actual evaporation.

  16. The Reference Value of Skeletal Muscle Mass Index for Defining the Sarcopenia of Women in Korea

    PubMed Central

    Kwon, Hyoung-Joon; Ha, Yong-Chan

    2015-01-01

    Background Sarcopenia is considering important disease entity in elderly. Several study groups define the sum of the muscle masses of the four limbs as appendicular skeletal mass (ASM) to calculate skeletal muscle index (SMI). The purpose of this study was to determine cut point of SMI for sarcopenia in Korean women. Methods This study was based on data obtained from the 2008 to 2011 Korean National Health and Nutrition Examination Survey (KNHANES) IV and V. A whole body dual energy X-ray absorptiometry scan were performed on individuals of ≥10 years old from July 2008 to May 2011. In the analysis, 11,633 women were included. ASM was calculated and SMI was obtained as ASM/height2. Cutoff value was defined two standard deviations below mean values for young reference group. Results Of 11,633 women aged 10 to 97 years, mean and standard deviation of year was 46.73±18.54 years. The highest level of height was noted in 20's and the highest total sum of skeletal mass was seen 14.87 kg in 40's. The highest value of SMI was noted in 60's in Korean women. Cutoff value as mean value of young women was decided with SMI of 30's and 40's that have peak ASM. Mean and standard deviation of SMI in those ages was 5.9±0.7 kg/m2. A SMI of two standard deviations below the mean SMI of reference groups was 4.4 kg/m2 as cutoff value. Conclusions This study shows that 4.4 kg/m2 of SMI in Korean women was cutoff value of sarcopenia. Further study is clearly required to decide cutoff value of SMI for sarcopenia, especially for Korean women. PMID:26082916

  17. Characterisation of chlorophyll a solubilised in sodium lauryl sulphate micelles

    NASA Astrophysics Data System (ADS)

    Mukherjee, T.; Sapre, A. V.; Mittal, Jai P.

    1980-01-01

    Poisson statistics has been applied to the problem of solubilisation of chlorophyll a in sodium lauryl sulphate micelles. Dilution experiments have been carried out to support the finding that each unit of chlorophyll a contributing to the 740 nm band contains just one chlorophyll a molecule.

  18. The Salmonid Rivers Observatory Network: Defining Reference Conditions for Salmon Rivers Around the Pacific.

    NASA Astrophysics Data System (ADS)

    Chilcote, S. D.; Stanford, J. A.

    2008-12-01

    The Salmonid Rivers Observatory River Project (SaRON) is a multi-year, multi-disciplinary project which has been assessing the state of intact, pristine salmon rivers around the Pacific Rim. The goal of this research is to illuminate the natural ecological functions of these dynamic and diverse systems as well as use the information to describe targets for restoration of impacted rivers. Our research has shown that the Shifting Habitat Mosaic (SHM) of unconstrained floodplain reaches is important in structuring the freshwater and riparian components of salmon ecosystems. The amount and productivity of available habitat in flood plains is a primary control on salmon abundance. Our research around the Pacific Rim has found that channel complexity is correlated with salmon abundance. Juvenile fish density linearly increased, R2=0.95, with a greater number of channel separations and returns. Some rivers with high habitat values had low salmon abundances. For example, the Kitlope River in British Columbia has channel complexity, 0.09 nodes per square km of watershed area, showing high habitat availability. Thus, our model predicted 3.48 fish per square meter but measured values 0.56 fishes per square meter. Paleolimnological study demonstrated a legacy over-harvest in this system, explaining the discrepancy between the actual and reference value. These results will be establishing reference values and ranges in natural variation.

  19. Using Gradient Analysis to Determine and Compare Invertebrate Responses to Urbanization: Can We Achieve Understanding Without Defining Reference Conditions?

    NASA Astrophysics Data System (ADS)

    Cuffney, T. F.; Giddings, E. M.; Coles, J. F.; Zappia, H.

    2005-05-01

    The U.S. Geological Survey's National Water-Quality Assessment Program uses a gradient design to investigate the effects of urbanization across the U.S. This design has successfully defined invertebrate responses in metropolitan areas associated with Boston, MA, Birmingham, AL, Salt Lake City, UT, and Raleigh, NC. An urban intensity index (UII) based on population, land use, land cover, and infrastructure is used to define the gradient without explicitly identifying reference sites, although the low end of the urban gradient may include such sites. Many invertebrate metrics (e.g., tolerance, biotic integrity, richness) are significantly related to UII. Detection of responses is not dependent upon reference conditions and this design can detect responses even when many low intensity (UII < 20) sites are excluded. Reference conditions can be inferred from regressions of metrics and UII by creating a "dummy" site where the components of the UII are set to background values (e.g., population = 0, road density = 0) and then extrapolating metrics for this site (UII = 0). Unfortunately, these end members (reference site conditions) tend to be highly variable and it is more difficult to determine these values than to detect the existence, form, and rate of response across the urban gradient.

  20. Modulated Chlorophyll "a" Fluorescence: A Tool for Teaching Photosynthesis

    ERIC Educational Resources Information Center

    Marques da Silva, Jorge; Bernardes da Silva, Anabela; Padua, Mario

    2007-01-01

    "In vivo" chlorophyll "a" fluorescence is a key technique in photosynthesis research. The recent release of a low cost, commercial, modulated fluorometer enables this powerful technology to be used in education. Modulated chlorophyll a fluorescence measurement "in vivo" is here proposed as a tool to demonstrate basic photosynthesis phenomena to…

  1. Mapping of chlorophyll a distributions in coastal zones

    NASA Technical Reports Server (NTRS)

    Johnson, R. W.

    1978-01-01

    It is pointed out that chlorophyll a is an important environmental parameter for monitoring water quality, nutrient loads, and pollution effects in coastal zones. High chlorophyll a concentrations occur in areas which have high nutrient inflows from sources such as sewage treatment plants and industrial wastes. Low chlorophyll a concentrations may be due to the addition of toxic substances from industrial wastes or other sources. Remote sensing provides an opportunity to assess distributions of water quality parameters, such as chlorophyll a. A description is presented of the chlorophyll a analysis and a quantitative mapping of the James River, Virginia. An approach considered by Johnson (1977) was used in the analysis. An application of the multiple regression analysis technique to a data set collected over the New York Bight, an environmentally different area of the coastal zone, is also discussed.

  2. Photoadaptation in marine phytoplankton: changes in spectral absorption and excitation of chlorophyll a fluorescence

    SciTech Connect

    Neori, A.; Holm-Hansen, O.; Mitchell, B.G.; Kiefer, D.A.

    1984-10-01

    The optical properties of marine phytoplankton were examined by measuring the absorption spectra and fluorescence excitation spectra of chlorophyll a for natural marine particles collected on glass fiber filters. Samples were collected at different depths from stations in temperate waters of the Southern California Bight and in polar waters of the Scotia and Ross Seas. At all stations, phytoplankton fluorescence excitation and absorption spectra changed systematically with depth and vertical stability of the water columns. In samples from deeper waters, both absorption and chlorophyll a fluorescence excitation spectra showed enhancement in the blue-to-green portion of the spectrum (470-560 nm) relative to that at 440 nm. Since similar changes in absorption and excitation were induced by incubating sea water samples at different light intensities, the changes in optical properties can be attributed to photoadaptation of the phytoplankton. The data indicate that in the natural populations studied, shade adaptation caused increases in the concentration of photosynthetic accessory pigments relative to chlorophyll a. These changes in cellular pigment composition were detectable within less than 1 day. Comparisons of absorption spectra with fluorescence excitation spectra indicate an apparent increase in the efficiency of sensitization of chlorophyll a fluorescence in the blue and green spectral regions for low light populations. 30 references, 6 figures.

  3. Time-Dependent Selection of an Optimal Set of Sources to Define a Stable Celestial Reference Frame

    NASA Technical Reports Server (NTRS)

    Le Bail, Karine; Gordon, David

    2010-01-01

    Temporal statistical position stability is required for VLBI sources to define a stable Celestial Reference Frame (CRF) and has been studied in many recent papers. This study analyzes the sources from the latest realization of the International Celestial Reference Frame (ICRF2) with the Allan variance, in addition to taking into account the apparent linear motions of the sources. Focusing on the 295 defining sources shows how they are a good compromise of different criteria, such as statistical stability and sky distribution, as well as having a sufficient number of sources, despite the fact that the most stable sources of the entire ICRF2 are mostly in the Northern Hemisphere. Nevertheless, the selection of a stable set is not unique: studying different solutions (GSF005a and AUG24 from GSFC and OPA from the Paris Observatory) over different time periods (1989.5 to 2009.5 and 1999.5 to 2009.5) leads to selections that can differ in up to 20% of the sources. Observing, recording, and network improvement are some of the causes, showing better stability for the CRF over the last decade than the last twenty years. But this may also be explained by the assumption of stationarity that is not necessarily right for some sources.

  4. Optical fiber underwater fluorometer for measuring chlorophyll-a concentration

    NASA Astrophysics Data System (ADS)

    Zheng, Longjiang; Hou, Peiguo; Wang, Yutian

    2000-10-01

    This paper describes an efficient method for in-situ measurement of chlorophyll-a concentration in the seawater with fluorescence method and optical fiber techniques. The instrument uses the pulsed xenon lamp as the excited light resources. Both the exciting light and the fluorescence from algae chlorophyll-a are transmitted along two fiber bundles. The fluorescent signal is detected by using the relevant pulsed detecting technology. The minimal detecting concentration of chlorophyll-a in the ocean can reach 1x10-5mg/cm3. The system has advantages of simple structure, passive sensor head and high sensitivity. The experimental results show that this measurement method is realizable.

  5. Spectral Feature Analysis for Quantitative Estimation of Cyanobacteria Chlorophyll-A

    NASA Astrophysics Data System (ADS)

    Lin, Yi; Ye, Zhanglin; Zhang, Yugan; Yu, Jie

    2016-06-01

    estimation of chlorophyll-a, and more effective than the traditional single band model; the best regression models for SR, NDVI with chlorophyll-a are linear and power, respectively. Under the condition without water disturbance, the single band model works the best. For the SR index, there are two optimal band combinations, which is comprised of infrared (700nm-900nm) and blue-green range (450nm-550nm), infrared and red range (600nm-650nm) respectively, with band width between 45nm to 125nm. For NDVI, the optimal band combination includes the range from 750nm to 900nm and 700nm to 750nm, with band width less than 30nm. For single band model, band center located between 733nm-935nm, and its width mustn't exceed the interval where band center located in. This study proved , as for SR or NDVI, the centers and widths are crucial factors for quantitative estimating chlorophyll-a. As for remote sensor, proper spectrum channel could not only improve the accuracy of recognizing cyanobacteria bloom, but reduce the redundancy of hyperspectral data. Those results will provide better reference for designing the suitable spectrum channel of customized sensors for cyanobacteria bloom monitoring at a low altitude. In other words, this study is also the basic research for developing the real-time remote sensing monitoring system with high time and high spatial resolution.

  6. Modeling of estuarne chlorophyll a from an airborne scanner

    USGS Publications Warehouse

    Khorram, Siamak; Catts, Glenn P.; Cloern, James E.; Knight, Allen W.

    1987-01-01

    Near simultaneous collection of 34 surface water samples and airborne multispectral scanner data provided input for regression models developed to predict surface concentrations of estuarine chlorophyll a. Two wavelength ratios were employed in model development. The ratios werechosen to capitalize on the spectral characteristics of chlorophyll a, while minimizing atmospheric influences. Models were then applied to data previously acquired over the study area thre years earlier. Results are in the form of color-coded displays of predicted chlorophyll a concentrations and comparisons of the agreement among measured surface samples and predictions basedon coincident remotely sensed data. The influence of large variations in fresh-water inflow to the estuary are clearly apparent in the results. The synoptic view provided by remote sensing is another method of examining important estuarine dynamics difficult to observe from in situ sampling alone.

  7. Chlorophyll-a in the rivers of eastern England.

    PubMed

    Neal, Colin; Hilton, John; Wade, Andrew J; Neal, Margaret; Wickham, Heather

    2006-07-15

    Chlorophyll-a concentration variations are described for two major river basins in England, the Humber and the Thames and related to catchment characteristics and nutrient concentrations across a range of rural, agricultural and urban/industrial settings. For all the rivers there are strong seasonal variations, with concentrations peaking in the spring and summer time when biological activity is at its highest. However, there are large variations in the magnitude of the seasonal effects across the rivers. For the spring-summer low-flow periods, average concentrations of chlorophyll-a correlate with soluble reactive phosphorus (SRP). Chlorophyll-a is also correlated with particulate nitrogen (PN), organic carbon (POC) and suspended sediments. However, the strongest relationships are with catchment area and flow, where two straight line relationships are observed. The results indicate the importance of residence times for determining planktonic growth within the rivers. This is also indicated by the lack of chlorophyll-a response to lowering of SRP concentrations in several of the rivers in the area due to phosphorus stripping of effluents at major sewage treatment works. A key control on chlorophyll-a concentration may be the input of canal and reservoir waters during the growing period: this too relates to issues of residence times. However, there may well be a complex series of factors influencing residence time across the catchments due to features such as inhomogeneous flow within the catchments, a fractal distribution of stream channels that leads to a distribution of residence times and differences in planktonic inoculation sources. Industrial pollution on the Aire and Calder seems to have affected the relationship of chlorophyll-a with PN and POC. The results are discussed in relation to the Water Framework Directive. PMID:16626783

  8. Associations between chlorophyll a and various microcystin health advisory concentrations

    PubMed Central

    Hollister, Jeffrey W.; Kreakie, Betty J.

    2016-01-01

    Cyanobacteria harmful algal blooms (cHABs) are associated with a wide range of adverse health effects that stem mostly from the presence of cyanotoxins. To help protect against these impacts, several health advisory levels have been set for some toxins. In particular, one of the more common toxins, microcystin, has several advisory levels set for drinking water and recreational use. However, compared to other water quality measures, field measurements of microcystin are not commonly available due to cost and advanced understanding required to interpret results. Addressing these issues will take time and resources. Thus, there is utility in finding indicators of microcystin that are already widely available, can be estimated quickly and in situ, and used as a first defense against high levels of microcystin. Chlorophyll a is commonly measured, can be estimated in situ, and has been shown to be positively associated with microcystin. In this paper, we use this association to provide estimates of chlorophyll a concentrations that are indicative of a higher probability of exceeding select health advisory concentrations for microcystin. Using the 2007 National Lakes Assessment and a conditional probability approach, we identify chlorophyll a concentrations that are more likely than not to be associated with an exceedance of a microcystin health advisory level. We look at the recent US EPA health advisories for drinking water as well as the World Health Organization levels for drinking water and recreational use and identify a range of chlorophyll a thresholds. A 50% chance of exceeding one of the specific advisory microcystin concentrations of 0.3, 1, 1.6, and 2 μg/L is associated with chlorophyll a concentration thresholds of 23, 68, 84, and 104 μg/L, respectively. When managing for these various microcystin levels, exceeding these reported chlorophyll a concentrations should be a trigger for further testing and possible management action. PMID:27127617

  9. Chlorophyll a algorithms for oligotrophic oceans: A novel approach based on three-band reflectance difference

    NASA Astrophysics Data System (ADS)

    Hu, Chuanmin; Lee, Zhongping; Franz, Bryan

    2012-01-01

    A new empirical algorithm is proposed to estimate surface chlorophyll a (Chl) concentrations in the global ocean for Chl ≤ 0.25 mg m-3(˜78% of the global ocean area). The algorithm is based on a color index (CI), defined as the difference between remote-sensing reflectance (Rrs, sr-1) in the green and a reference formed linearly between Rrsin the blue and red. For low-Chl waters, in situ data showed a tighter (and therefore better) relationship between CI and Chl than between traditional band ratios and Chl, which was further validated using global data collected concurrently by ship-borne and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer (MODIS)/Aqua instruments. Model simulations showed that for low-Chl waters, compared with the band-ratio algorithm, the CI-based algorithm (CIA) was more tolerant to changes in chlorophyll-specific backscattering coefficient and performed similarly for different relative contributions of nonphytoplankton absorption. Simulations using existing atmospheric correction approaches further demonstrated that the CIA was much less sensitive than band-ratio algorithms to various errors induced by instrument noise and imperfect atmospheric correction (including sun glint and whitecap corrections). Image and time series analyses of SeaWiFS and MODIS/Aqua data also showed improved performance in terms of reduced image noise, more coherent spatial and temporal patterns, and better consistency between the two sensors. The reduction in noise and other errors is particularly useful to improve the detection of various ocean features such as eddies. Preliminary tests over Medium-Resolution Imaging Spectrometer and Coastal Zone Color Scanner data indicate that the new approach should be generally applicable to all past, current, and future ocean color instruments.

  10. Chlorophyll a spatial inference using artificial neural network from multispectral images and in situ measurements.

    PubMed

    Ferreira, Monique S; Galo, Maria De Lourdes B T

    2013-01-01

    Considering the importance of monitoring the water quality parameters, remote sensing is a practicable alternative to limnological variables detection, which interacts with electromagnetic radiation, called optically active components (OAC). Among these, the phytoplankton pigment chlorophyll a is the most representative pigment of photosynthetic activity in all classes of algae. In this sense, this work aims to develop a method of spatial inference of chlorophyll a concentration using Artificial Neural Networks (ANN). To achieve this purpose, a multispectral image and fluorometric measurements were used as input data. The multispectral image was processed and the net training and validation dataset were carefully chosen. From this, the neural net architecture and its parameters were defined to model the variable of interest. In the end of training phase, the trained network was applied to the image and a qualitative analysis was done. Thus, it was noticed that the integration of fluorometric and multispectral data provided good results in the chlorophyll a inference, when combined in a structure of artificial neural networks. PMID:23828358

  11. AIRBONE LASER FLUOROSENSING OF SURFACE WATER CHLOROPHYLL 'A'

    EPA Science Inventory

    A prototype airborne laser fluorosensor for monitoring surface water chlorophyll 'a' has been tested over Lake Mead, Nevada. Trends in the remotely sensed data are in close correspondence with ground truth data. It is suggested that system performance can be improved by concurren...

  12. Cool, elevated chlorophyll-a waters off northern Mozambique

    NASA Astrophysics Data System (ADS)

    Malauene, B. S.; Shillington, F. A.; Roberts, M. J.; Moloney, C. L.

    2014-02-01

    Direct in-situ observations from a shallow underwater temperature recorder on the continental shelf and from a shipboard oceanographic survey, were combined with MODIS satellite data (sea surface temperature and chlorophyll-a) to assess the temporal and spatial variability of temperature and chlorophyll-a in the Mozambique Channel near the coastal town of Angoche, 16°S. Intermittent, relatively cool surface water and elevated chlorophyll-a signatures were found, indicating upwelling near Angoche over an area between 15°S and 18°S. A 5-year (2002-2007) analysis of temperature (from both in-situ and satellite) revealed two distinct periods: (1) the August-March period with highly variable intermittent "cool water" events and (2) the April-July period with little temperature variability. Generally, periods of cooling occurred at about 2 months intervals, but shorter period occurrences (8-30 days) of cool coastal events were also observed. Two possible forcing mechanisms are discussed: (1) wind derived coastal upwelling (using satellite blended sea surface wind derived from NOAA/NCDC) and (2) the effect of passing transient southward moving eddies (using sea level anomalies from AVISO altimetry). It is suggested that the cool surface, elevated chlorophyll-a waters are primed and formed by favourable wind-driven Ekman-type coastal upwelling, responding to alongshore northeasterly monsoon winds prevailing between August and March. These waters are then enhanced in chlorophyll-a and advected further offshore by anti-cyclonic/cyclonic eddy pairs interacting with the shelf.

  13. Defining the Reference Condition for Wadeable Streams in the Sand Hills Subdivision of the Southeastern Plains Ecoregion, USA

    NASA Astrophysics Data System (ADS)

    Kosnicki, Ely; Sefick, Stephen A.; Paller, Michael H.; Jarrell, Miller S.; Prusha, Blair A.; Sterrett, Sean C.; Tuberville, Tracey D.; Feminella, Jack W.

    2014-09-01

    The Sand Hills subdivision of the Southeastern Plains ecoregion has been impacted by historical land uses over the past two centuries and, with the additive effects of contemporary land use, determining reference condition for streams in this region is a challenge. We identified reference condition based on the combined use of 3 independent selection methods. Method 1 involved use of a multivariate disturbance gradient derived from several stressors, method 2 was based on variation in channel morphology, and method 3 was based on passing 6 of 7 environmental criteria. Sites selected as reference from all 3 methods were considered primary reference, whereas those selected by 2 or 1 methods were considered secondary or tertiary reference, respectively. Sites not selected by any of the methods were considered non-reference. In addition, best professional judgment (BPJ) was used to exclude some sites from any reference class, and comparisons were made to examine the utility of BPJ. Non-metric multidimensional scaling indicated that use of BPJ may help designate non-reference sites when unidentified stressors are present. The macroinvertebrate community measures Ephemeroptera, Plecoptera, Trichoptera richness and North Carolina Biotic Index showed no differences between primary and secondary reference sites when BPJ was ignored. However, there was no significant difference among primary, secondary, and tertiary reference sites when BPJ was used. We underscore the importance of classifying reference conditions, especially in regions that have endured significant anthropogenic activity. We suggest that the use of secondary reference sites may enable construction of models that target a broader set of management interests.

  14. Transmit-reference methods in software defined radio platforms for communication in harsh propagation environments and systems thereof

    DOEpatents

    Dowla, Farid U; Nekoogar, Faranak

    2015-03-03

    A method for adaptive Radio Frequency (RF) jamming according to one embodiment includes dynamically monitoring a RF spectrum; detecting any undesired signals in real time from the RF spectrum; and sending a directional countermeasure signal to jam the undesired signals. A method for adaptive Radio Frequency (RF) communications according to another embodiment includes transmitting a data pulse in a RF spectrum; and transmitting a reference pulse separated by a predetermined period of time from the data pulse; wherein the data pulse is modulated with data, wherein the reference pulse is unmodulated. A method for adaptive Radio Frequency (RF) communications according to yet another embodiment includes receiving a data pulse in a RF spectrum; and receiving a reference pulse separated in time from the data pulse, wherein the data pulse is modulated with data, wherein the reference pulse is unmodulated; and demodulating the pulses.

  15. Elucidation of Genetic Backgrounds Necessary for Chlorophyll a Biosynthesis Toward Artificial Creation of Oxygenic Photosynthesis

    NASA Astrophysics Data System (ADS)

    Tsukatani, Yusuke; Masuda, Shinji

    2015-09-01

    We succeeded to create the genetically modified purple photosynthetic bacterium capable of synthesizing chlorophyll a. The results indicate that not only chlorophyll synthase, but also an enzyme for galactolipid synthesis and reaction center proteins are required for accumulating chlorophyll a.

  16. Use of Expert Panels to Define the Reference Standard in Diagnostic Research: A Systematic Review of Published Methods and Reporting

    PubMed Central

    Bertens, Loes C. M.; Broekhuizen, Berna D. L.; Naaktgeboren, Christiana A.; Rutten, Frans H.; Hoes, Arno W.; van Mourik, Yvonne; Moons, Karel G. M.; Reitsma, Johannes B.

    2013-01-01

    Background In diagnostic studies, a single and error-free test that can be used as the reference (gold) standard often does not exist. One solution is the use of panel diagnosis, i.e., a group of experts who assess the results from multiple tests to reach a final diagnosis in each patient. Although panel diagnosis, also known as consensus or expert diagnosis, is frequently used as the reference standard, guidance on preferred methodology is lacking. The aim of this study is to provide an overview of methods used in panel diagnoses and to provide initial guidance on the use and reporting of panel diagnosis as reference standard. Methods and Findings PubMed was systematically searched for diagnostic studies applying a panel diagnosis as reference standard published up to May 31, 2012. We included diagnostic studies in which the final diagnosis was made by two or more persons based on results from multiple tests. General study characteristics and details of panel methodology were extracted. Eighty-one studies were included, of which most reported on psychiatry (37%) and cardiovascular (21%) diseases. Data extraction was hampered by incomplete reporting; one or more pieces of critical information about panel reference standard methodology was missing in 83% of studies. In most studies (75%), the panel consisted of three or fewer members. Panel members were blinded to the results of the index test results in 31% of studies. Reproducibility of the decision process was assessed in 17 (21%) studies. Reported details on panel constitution, information for diagnosis and methods of decision making varied considerably between studies. Conclusions Methods of panel diagnosis varied substantially across studies and many aspects of the procedure were either unclear or not reported. On the basis of our review, we identified areas for improvement and developed a checklist and flow chart for initial guidance for researchers conducting and reporting of studies involving panel

  17. Integrating Biology into the General Chemistry Laboratory: Fluorometric Analysis of Chlorophyll "a"

    ERIC Educational Resources Information Center

    Wesolowski, Meredith C.

    2014-01-01

    A laboratory experiment that introduces fluorometry of chlorophyll "a" at the general chemistry level is described. The use of thin-layer chromatography to isolate chlorophyll "a" from spirulina and leaf matter enables quantification of small amounts of chlorophyll "a" via fluorometry. Student results were reasonably…

  18. Relations between water physico-chemistry and benthic algal communities in a northern Canadian watershed: defining reference conditions using multiple descriptors of community structure.

    PubMed

    Thomas, Kathryn E; Hall, Roland I; Scrimgeour, Garry J

    2015-09-01

    Defining reference conditions is central to identifying environmental effects of anthropogenic activities. Using a watershed approach, we quantified reference conditions for benthic algal communities and their relations to physico-chemical conditions in rivers in the South Nahanni River watershed, NWT, Canada, in 2008 and 2009. We also compared the ability of three descriptors that vary in terms of analytical costs to define algal community structure based on relative abundances of (i) all algal taxa, (ii) only diatom taxa, and (iii) photosynthetic pigments. Ordination analyses showed that variance in algal community structure was strongly related to gradients in environmental variables describing water physico-chemistry, stream habitats, and sub-watershed structure. Water physico-chemistry and local watershed-scale descriptors differed significantly between algal communities from sites in the Selwyn Mountain ecoregion compared to sites in the Nahanni-Hyland ecoregions. Distinct differences in algal community types between ecoregions were apparent irrespective of whether algal community structure was defined using all algal taxa, diatom taxa, or photosynthetic pigments. Two algal community types were highly predictable using environmental variables, a core consideration in the development of Reference Condition Approach (RCA) models. These results suggest that assessments of environmental impacts could be completed using RCA models for each ecoregion. We suggest that use of algal pigments, a high through-put analysis, is a promising alternative compared to more labor-intensive and costly taxonomic approaches for defining algal community structure. PMID:26255271

  19. Testing Three Species Distribution Modelling Strategies to Define Fish Assemblage Reference Conditions for Stream Bioassessment and Related Applications

    PubMed Central

    Rose, Peter M.; Kennard, Mark J.; Moffatt, David B.; Sheldon, Fran; Butler, Gavin L.

    2016-01-01

    Species distribution models are widely used for stream bioassessment, estimating changes in habitat suitability and identifying conservation priorities. We tested the accuracy of three modelling strategies (single species ensemble, multi-species response and community classification models) to predict fish assemblages at reference stream segments in coastal subtropical Australia. We aimed to evaluate each modelling strategy for consistency of predictor variable selection; determine which strategy is most suitable for stream bioassessment using fish indicators; and appraise which strategies best match other stream management applications. Five models, one single species ensemble, two multi-species response and two community classification models, were calibrated using fish species presence-absence data from 103 reference sites. Models were evaluated for generality and transferability through space and time using four external reference site datasets. Elevation and catchment slope were consistently identified as key correlates of fish assemblage composition among models. The community classification models had high omission error rates and contributed fewer taxa to the ‘expected’ component of the taxonomic completeness (O/E50) index than the other strategies. This potentially decreases the model sensitivity for site impact assessment. The ensemble model accurately and precisely modelled O/E50 for the training data, but produced biased predictions for the external datasets. The multi-species response models afforded relatively high accuracy and precision coupled with low bias across external datasets and had lower taxa omission rates than the community classification models. They inherently included rare, but predictable species while excluding species that were poorly modelled among all strategies. We suggest that the multi-species response modelling strategy is most suited to bioassessment using freshwater fish assemblages in our study area. At the species level

  20. Determination of chlorophyll-a concentration under desertic dust.

    NASA Astrophysics Data System (ADS)

    Brajard, Julien; Diouf, Daouda; Brehmer, Patrice; Crépon, Michel; Lazar, Alban; Machu, Eric; Thiria, Sylvie; Capet, Xavier

    2015-04-01

    One major challenge in ocean colour remote sensing is the so-called atmospheric correction. It consists in removing the atmospheric signal from the signal measured from space by a radiometer. If an accurate atmospheric correction is performed, it is thus possible to invert the water-leaving reflectance signal to estimate in-water properties such as the chlorophyll-a concentration. Ocean colour data centers proposed a standard atmospheric correction scheme specific to the sensor they processed (SeaWiFS, MERIS, MODIS, VIIRS, …). They are accurate in most situations (open ocean waters, weakly absorbing aeorols) but fail in some specific cases such as the presence of desertic dust in the atmosphere. In some region, they can lead to exclude large regions of the image from the treatment. In this work, we propose an algorithm to perform the atmospheric correction and to determine the chlorophyll-a concentration under desertic dust. This algorithm, called SOM-NV, is a combination of a classification of the aerosol type using a self-organizing map and an inversion scheme called NeuroVaria. It has been applied to the Senegalo-Mauritanean upwelling using SeaWiFS, MODIS and VIIRS data. The results of SOM-NV have been compared with in-situ measurements (HPLC and microscope) sampled during the UPSEN (UPwelling SENegal) campaigns in 2012 and 2013.

  1. Fuel oil effect on the population growth, species diversity and chlorophyll (a) content of freshwater microalgae.

    PubMed

    El-Dib, M A; Abou-Waly, H F; El-Naby, A H

    2001-06-01

    Fresh water algae were subjected to different concentrations (0.03, 0.07, 0.12, 0.25 and 0.5 g x l(-1)) of aqueous extract of reference fuel oil (EPA, USA, API Oil No. 2, 38% aromatic, 1274). Significant decrease in Chlorophyll. (a) was observed as the concentration of fuel oil was increased. The EC50 value of fuel oil after 7 days was 0.29 g x l(-1). Total algal counts and growth rate decreased in response to the studied fuel oil. High diversity values in diatoms were observed in all treated aqueous cultures. High concentrations of fuel oil significantly decreased carbohydrate and protein contents of algal cells. PMID:11382351

  2. Chlorophyll-a Algorithms for Oligotrophic Oceans: A Novel Approach Based on Three-Band Reflectance Difference

    NASA Technical Reports Server (NTRS)

    Hu, Chuanmin; Lee, Zhongping; Franz, Bryan

    2011-01-01

    A new empirical algorithm is proposed to estimate surface chlorophyll-a concentrations (Chl) in the global ocean for Chl less than or equal to 0.25 milligrams per cubic meters (approximately 77% of the global ocean area). The algorithm is based on a color index (CI), defined as the difference between remote sensing reflectance (R(sub rs), sr(sup -1) in the green and a reference formed linearly between R(sub rs) in the blue and red. For low Chl waters, in situ data showed a tighter (and therefore better) relationship between CI and Chl than between traditional band-ratios and Chl, which was further validated using global data collected concurrently by ship-borne and SeaWiFS satellite instruments. Model simulations showed that for low Chl waters, compared with the band-ratio algorithm, the CI-based algorithm (CIA) was more tolerant to changes in chlorophyll-specific backscattering coefficient, and performed similarly for different relative contributions of non-phytoplankton absorption. Simulations using existing atmospheric correction approaches further demonstrated that the CIA was much less sensitive than band-ratio algorithms to various errors induced by instrument noise and imperfect atmospheric correction (including sun glint and whitecap corrections). Image and time-series analyses of SeaWiFS and MODIS/Aqua data also showed improved performance in terms of reduced image noise, more coherent spatial and temporal patterns, and consistency between the two sensors. The reduction in noise and other errors is particularly useful to improve the detection of various ocean features such as eddies. Preliminary tests over MERIS and CZCS data indicate that the new approach should be generally applicable to all existing and future ocean color instruments.

  3. [Retrieving for chlorophyll-a concentration and suspended substance concentration based on HJ-1A HIS image].

    PubMed

    Yang, Ting; Zhang, Hui; Wang, Qiao; Zhao, Qiao-Hua

    2011-11-01

    Based on geometry correction using ERDAS software and radiation correction using 6S model for HJ-1A hyper-spectrum image (HSI) on May 2 in 2010 and the analysis of spectrum for water data and spectral data of hyper-spectrum image, this paper processes original spectrum data of 28 sample points using method of normalization and method of first-order derivation. Single-band and band combination are selected to establish inversion models of the concentration of chlorophyll-a and solid suspensions. Choosing the model with biggest correlation coefficient, the spatial distribution map of the concentration of chlorophyll-a and solid suspensions content in Taihu Lake is acquired. The research results show: Band-73 of hyper-spectrum image which has been normalized shows the biggest correlation coefficient of the concentration of chlorophyll-a, remote sensing sediment parameter shows the biggest correlation coefficient of the concentration of solid suspensions, the result is consistent with analysis of spectral data of hyper-spectrum image. Average relative errors of predicted and measured values are within 30 percent. Spatial distribution map of water quality is consistent with the result of field surveys. Therefore, based on reference of the analysis of sensitive band of spectrum for water data, HJ-1A hyper-spectrum image can give quantitative estimation of water quality parameters in Taihu Lake. PMID:22295614

  4. Decadal variability of chlorophyll a in the South China Sea: a possible mechanism

    NASA Astrophysics Data System (ADS)

    Liu, Fenfen; Chen, Chuqun; Zhan, Haigang

    2012-11-01

    Four climatologies on a monthly scale (January, April, May and November) of chlorophyll a within the South China Sea (SCS) were calculated using a Coastal Zone Color Scanner (CZCS) (1979-1983) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) (1998-2002). We analyzed decadal variability of chlorophyll a by comparing the products of the two observation periods. The relationships of variability in chlorophyll a with sea surface wind speed (SSW), sea surface temperature (SST), wind stress (WS), and mixed layer depth (MLD) were determined. The results indicate that there is obvious chlorophyll a decadal variability in the SCS. The decadal chlorophyll a presents distinct seasonal variability in characteristics, which may be as a result of various different dynamic processes. The negative chlorophyll a concentration anomaly in January was associated with the warming of SST and a shallower MLD. Generally, there were higher chlorophyll a concentrations in spring during the SeaWiFS period compared with the CZCS period. However, the chlorophyll a concentration exhibits some regional differences during this season, leading to an explanation being diffi cult. The deepened MLD may have contributed to the positive chlorophyll a concentration anomalies from the northwestern Luzon Island to the northeastern region of Vietnam during April and May. The increases of chlorophyll a concentration in northwestern Borneo during May may be because the stronger SSW and higher WS produce a deeper mixed layer and convective mixing, leading to high levels of nutrient concentrations. The higher chlorophyll a off southeastern Vietnam may be associated with the advective transport of the colder water extending from the Karimata Strait to southeastern Vietnam.

  5. Chlorophyll a triplet-state ESR in frozen phosphatidylcholine vesicles

    SciTech Connect

    Hiromitsu, I.; Kevan, L.

    1988-05-19

    Photoexcited chlorophyll a (Chla) triplet state in rapidly frozen egg phosphatidylcholine (EPC) vesicles is investigated at 77 K by electron spin resonance (ESR) spectroscopy using light intensity modulation. The electron spin polarization (ESP) intensity is stronger for 0.2 mM Chla than for 1.0 mM Chla. The absolute values of the zero field splitting parameter, D, are 283 (+/-1) x 10/sup -4/ and 276 (+/-2) x 10/sup -4/ cm/sup -1/, and the average depopulation rates of the triplet state are 0.671 +/- 0.052 and 1.054 +/- 0.036 ms/sup -1/ for 0.2 mM Chla and 1.0 mM Chla, respectively. This difference can be consistently attributed to faster triplet-state migration between adjacent Chla's at the higher 1.0 mM Chla concentration. A characteristic migration time of 2.6 ms is obtained. The ESP pattern of the Chla triplet state in the frozen EPC vesicles resembles that in polycrystals more than that in glasses. This suggests that the local environment around Chla in the vesicles is more structured than in glasses.

  6. Elucidation of Genetic Backgrounds Necessary for Chlorophyll a Biosynthesis Toward Artificial Creation of Oxygenic Photosynthesis.

    PubMed

    Tsukatani, Yusuke; Masuda, Shinji

    2015-09-01

    We succeeded to create the genetically modified purple photosynthetic bacterium capable of synthesizing chlorophyll a. The results indicate that not only chlorophyll synthase, but also an enzyme for galactolipid synthesis and reaction center proteins are required for accumulating chlorophyll a. PMID:26021277

  7. Peridinin-Chlorophyll a Proteins of the Dinoflagellate Amphidinium carterae (Plymouth 450) 1

    PubMed Central

    Haxo, Francis T.; Kycia, J. Helen; Somers, G. Fred; Bennett, Allen; Siegelman, Harold W.

    1976-01-01

    The marine dinoflagellate Amphidinium carterae (Plymouth 450) releases several water-soluble peridinin-chlorophyll a proteins after freezethawing. These chromoproteins have a molecular weight of 39.2 × 103 and are comprised of noncovalently bound peridinin and chlorophyll a and a nonoligomeric protein. They have distinct isoelectric points and may be resolved into six components by either isoelectric focusing on polyacrylamide gel or ion exchange chromatography. The predominant chromoprotein, which has a pI of 7.5, constitutes about 90% of the extractable peridinin-chlorophyll a protein. It consists of an alanine-rich apoprotein of molecular weight 31.8 × 103 stoichiometrically associated with 9 peridinin and 2 chlorophyll a molecules. Additionally, the peridinin-chlorophyll a proteins with pI values of 7.6 and 6.4 were purified and found to have amino acid and chromophore composition essentially identical with the pI 7.5 protein. Peridinin-chlorophyll a protein, pI 7.5, after treatment at alkaline pH was transformed into several more acid pI forms of the protein, strongly suggesting that the naturally occurring proteins are deamidation products of a single protein. Fluorescence excitation and emission spectra demonstrate that light energy absorbed by peridinin induces chlorophyll a fluorescence presumably by intramolecular energy transfer. The peridinin-chlorophyll a proteins presumably function in vivo as photosynthetic light-harvesting pigments. PMID:16659470

  8. Measuring chlorophyll a concentrations in the Sea of Japan using probe and flow fluorimeters

    NASA Astrophysics Data System (ADS)

    Zakharkov, S. P.; Shtraikhert, E. A.; Shambarova, Y. V.; Gordeichuk, T. N.; Shi, X.

    2016-05-01

    The spatial variability of chlorophyll a concentrations was studied from the data of two near-shore expeditions and the cruise of the R/V Akademik M.A. Lavrent'ev in October-November 2010 over the northwestern part of the Sea of Japan. The sections across eddies showed a maximum of chlorophyll a at a depth of 40 m. According to the data from the cruise, the chlorophyll a concentration was maximum in the north of the sea and decreased to the south. In parallel, the procedures for chlorophyll a determination were compared for spectrophotometry with a fluorescence probe and a fluorescence flow system. The probe data of chlorophyll a fluorescence showed a high correlation with the chlorophyll a concentrations by spectrophotometry. On the contrary, data on chlorophyll a concentrations from spectrophotometry did not agree with those from the flow system. It was shown that a fluorimeter in the flow system recorded dissolved organic matter along with the chlorophyll a fluorescence.

  9. Serum erythropoietin and its relation with soluble transferrin receptor in patients with different types of anaemia in a locally defined reference population.

    PubMed

    Roque, M E; Sandoval, M J; Aggio, M C

    2001-10-01

    Serum erythropoietin (Epo) and soluble transferrin receptor (sTR) were measured in a locally defined reference population (n=100): healthy volunteers (n=50); iron- deficiency anaemia (n=41) and haemolytic anaemia (n=9) (beta-thalassaemia, n = 4; autoimmune, n=5). Our data demonstrated an inverse relationship between erythroid activity and Epo levels. The regression line between Ln Epo and haemoglobin (Hb) was highly significant: P < 0.0001, r2=0.8275, Ln Epo=8.5346-0.04275 Hb, confidence limit 95%. The mean observed/predicted (O/P) ratio of Ln (Epo) was 1.01 +/- 0.11. We demonstrated that the serum Epo concentration in this particular population correlated consistently with clinical measures of erythropoietic activity. sTR, a new index of erythropoiesis, varied from 16.1 to 148 nmol/l, mean 62.0 nmol/l in the anaemic patients' group. The relationship between Ln Epo and Ln sTR was highly significant: P < 0.0001. We conclude that locally defined regression analyses are crucial for correct data interpretation and can indicate whether or not Epo production is appropriate or inappropriate. Serial determinations of sTR could help in the assessment of response to therapeutic doses of Epo. PMID:11703410

  10. Internal Conversion and Vibrational Energy Redistribution in Chlorophyll A.

    PubMed

    Shenai, Prathamesh M; Fernandez-Alberti, Sebastian; Bricker, William P; Tretiak, Sergei; Zhao, Yang

    2016-01-14

    We have computationally investigated the role of intramolecular vibrational modes in determining nonradiative relaxation pathways of photoexcited electronic states in isolated chlorophyll A (ChlA) molecules. To simulate the excited state relaxation from the initially excited Soret state to the lowest excited state Qy, the approach of nonadiabatic excited state molecular dynamics has been adopted. The intramolecular vibrational energy relaxation and redistribution that accompany the electronic internal conversion process is followed by analyzing the excited state trajectories in terms of the ground state equilibrium normal modes. The time dependence of the normal mode velocities is determined by projecting instantaneous Cartesian velocities onto the normal mode vectors. Our analysis of the time evolution of the average mode energies uncovers that only a small subset of the medium-to-high frequency normal modes actively participate in the electronic relaxation processes. These active modes are characterized by the highest overlap with the nonadiabatic coupling vectors (NACRs) during the electronic transitions. Further statistical analysis of the nonadiabatic transitions reveals that the electronic and vibrational energy relaxation occurs via two distinct pathways with significantly different time scales on which the hopping from Soret to Qx occurs thereby dictating the overall dynamics. Furthermore, the NACRs corresponding to each of the transitions have been consistently found to be predominantly similar to a set of normal modes that vary depending upon the transition and the identified categories. Each pathway exhibits a differential time scale of energy transfer and also a differential set of predominant active modes. Our present analysis can be considered as a general approach allowing identification of a reduced subset of specific vibrational coordinates associated with nonradiative relaxation pathways. Therefore, it represents an adequate prior strategy that

  11. Horizontal distributions of surface chlorophyll a and nitrogenous nutrients near Bering Strait and Unimak Pass

    NASA Astrophysics Data System (ADS)

    Koike, Isao; Furuya, Ken; Otobe, Hirotake; Nakai, Toshisuke; Memoto, Takahisa; Hattori, Akihiko

    1982-02-01

    Surface temperature, salinity, nitrate,aammonium, and chlorophyll a were continuously monitored along a north-south transect across the Bering Strait and Unimak Pass region of the southeastern Bering Sea in July 1978. A cold water mass, rich in nitrate and chlorophyll a, north of the Bering Strait, was examined over a distance of 40 km; it was probably associated with local upwelling. Near Unimak Pass, chlorophyll a was inversely correlated with nitrate, suggesting rapid growth of phytoplankton in nutrient-rich Alaskan Stream water during its travel into the Bering Sea. Phytoplankton species composition was consistent with this inference.

  12. Reflectance model for quantifying chlorophyll a in the presence of productivity degradation products

    NASA Technical Reports Server (NTRS)

    Carder, K. L.; Hawes, S. K.; Steward, R. G.; Baker, K. A.; Smith, R. C.; Mitchell, B. G.

    1991-01-01

    A reflectance model developed to estimate chlorophyll a concentrations in the presence of marine colored dissolved organic matter, pheopigments, detritus, and bacteria is presented. Nomograms and lookup tables are generated to describe the effects of different mixtures of chlorophyll a and these degradation products on the R(412):R(443) and R(443):R(565) remote-sensing reflectance or irradiance reflectance ratios. These are used to simulate the accuracy of potential ocean color satellite algorithms, assuming that atmospheric effects have been removed. For the California Current upwelling and offshore regions, with chlorophyll a not greater than 1.3 mg/cu m, the average error for chlorophyll a retrievals derived from irradiance reflectance data for degradation product-rich areas was reduced from +/-61 percent to +/-23 percent by application of an algorithm using two reflectance ratios rather than the commonly used algorithm applying a single reflectance ratio.

  13. An algorithm for computing chlorophyll-a concentrations using a dual-frequency fluorosensor

    NASA Technical Reports Server (NTRS)

    Campbell, J. W.

    1981-01-01

    An algorithm to be used on data from a dual-frequency fluorosensor (i.e. one using two wavelengths for excitation of chlorophyll-a fluorescence) to compute total chlorophyll-a concentration and to partition that chlorophyll between two color groups present in a mixed phytoplankton population is described. The algorithm is based on laboratory and field-testing experience gained with the airborne lidar oceanographic probing experiment fluorosensor.

  14. Modeling chlorophyll-a concentration in Taihu Lake based on different trophic state

    NASA Astrophysics Data System (ADS)

    Wang, Li-zhen; Li, Yun-mei; Le, Cheng-feng; Sun, De-yong

    2008-10-01

    In this paper, we want to search for the hyperspectral remote sensing bands most sensitive to chlorophyll-a concentration in different trophic states. Through repeated measurements in Taihu Lake, a large quantity of hyperspectral reflectance data and chlorophyll-a concentration data of lake were obtained from June to September of 2004 and 2005. The eligible hyperspectral data were analyzed to calculate remote sensing reflectance of water in Taihu Lake, and the data of chlorophyll-a concentration obtained from laboratory analysis were used to calculate Trophic State Index. According to the actual condition of Taihu Lake, the hyperspectral data were divided into three groups: mesotropher, eutropher and hyper eutropher. In each trophic state, chlorophyll-a concentration was then regressed against to identify the most sensitive hyperspectral bands. From the established regression models, we can get the conclusion: chlorophyll-a concentration is correspondingly lower under mesotrophic state, badly influenced by suspended matter, the spectral feature of chlorophyll-a is not evident, and the accuracy of regression model in this trophic state is not so satisfactory; in eutrophic state, differential algorithm has better retrieval result, the linear model based on this algorithm has the best estimation result; under hyper eutrophic state, the estimation accuracy is higher than the other two states as a whole. The fitting precision is the highest using the band ratio R719/R670 as independent variable in the quadratic equation model.

  15. [Estimation and forecast of chlorophyll a concentration in Taihu Lake based on ensemble square root filters].

    PubMed

    Li, Yuan; Li, Yun-Mei; Wang, Qiao; Zhang, Zhuo; Guo, Fei; Lü, Heng; Bi, Kun; Huang, Chang-Chun; Guo, Yu-Long

    2013-01-01

    Chlorophyll a concentration is one of the important parameters for the characterization of water quality, which reflects the degree of eutrophication and algae content in the water body. It is also an important factor in determining water spectral reflectance. Chlorophyll a concentration is an important water quality parameter in water quality remote sensing. Remote sensing quantitative retrieval of chlorophyll a concentration can provide new ideas and methods for the monitoring and evaluation of lake water quality. In this work, we developed a data assimilation scheme based on ensemble square root filters and three-dimensional numerical modeling for wind-driven circulation and pollutant transport to assimilate the concentration of chlorophyll a. We also conducted some assimilation experiments using buoy observation data on May 20, 2010. We estimated the concentration of chlorophyll a in Taihu Lake, and then used this result to forecast the concentration of chlorophyll a. During the assimilation stage, the root mean square error reduced from 1.58, 1.025, and 2.76 to 0.465, 0.276, and 1.01, respectively, and the average relative error reduced from 0.2 to 0.05, 0.046, and 0.069, respectively. During the prediction stage, the root mean square error reduced from 1.486, 1.143, and 2.38 to 0.017, 0.147, and 0.23, respectively, and the average relative error reduced from 0.2 to 0.002, 0.025, and 0.019, respectively. The final results indicate that the method of data assimilation can significantly improve the accuracy in the estimation and prediction of chlorophyll a concentration in Taihu Lake. PMID:23487919

  16. Satellite Remote Sensing of Chlorophyll-a Concentrations in the Galveston Bay, Texas

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Zheng, G.; Gao, H.; Roelke, D.

    2014-12-01

    Galveston Bay (Texas) is characterized by the unique and complex mixing of waters allowing the bay to produce more seafood than any bay in the United States with the exception of Chesapeake Bay (Maryland). The concentration of Chlorophyll-a plays a key role in ecosystem productivity. Since field measurements are complicated and expensive, satellite remote sensing provides an opportunity to observe real-time variations of Chlorophyll-a at a large spatial scale. However, because of the notable influences caused by the absorption and scattering of other substances (such as total suspended solids, dissolved organic matters and tripton), the use of ocean color remote sensing images to estimate Chlorophyll-a in coastal waters is usually limited. In order to monitor the variation of Chlorophyll-a with high accuracy (and at a high temporal resolution), an algorithm was developed using Terra Moderate Resolution Imaging Spectroradiometer (MODIS) reflectance data, Landsat Thematic Mapper (TM) images, and in-situ measurements. This approach mainly contains two steps. First, based on the relatively high spatial resolution of Landsat images (30m), an exponential regression relationship was found between the Landsat reflectance ratio (i.e., band 3/band 4) and the in-situ measured Chlorophyll-a concentrations (R2 = 0.81) during the two-year sampling period (2005- 2006). By using an automatic outlier detection technique for quality control, a Landsat Chlorophyll-a concentration product from 2000- 2011 was generated. Second, in order to improve the temporal resolution over the bay area, an 8-day MODIS product at 500 m spatial resolution from 2000 to 2013 was created. Landsat results from the first step were employed to calibrate the parameters used in NASA's existing operational product algorithm. This way, the MODIS product from this study can best represent the phytoplankton productivity in Galveston Bay. Using the remotely sensed Chlorophyll-a product, further comparisons were

  17. [Quantitative retrieval of chlorophyll a concentration in Taihu Lake using machine learning methods].

    PubMed

    Zhang, Yu-Chao; Qian, Xin; Qian, Yu; Liu, Jian-Ping; Kong, Fan-Xiang

    2009-05-15

    We evaluated the performance of two machine learning methods, artificial neural net (ANN) and support vector machine (SVM), for estimation of chlorophyll a in Taihu Lake from remote sensing data. The theoretical analysis has been done from basic theory and learning target of these two methods first. Then two empirical algorithms have been developed to relate reflectance of MODIS to in situ concentrations of chlorophyll a. The performance of ANN and SVM is comparatively analyzed in terms of validation, stability and robustness assessment and chlorophyll a distribution of Taihu Lake from two algorithms. The root of mean square deviation (RMSE) and average relative error (ARE) of validation data is only 5.85 and 26.5% of SVM retrieval model, however, RMSE and ARE of ANN model is 13.04 and 46.8%. Stability and robustness assessment suggest that SVM provides the better performance than ANN. And the retrieval results show that the chlorophyll a distribution of the whole lake from two algorithms is similar, however, the chlorophyll a concentration in the eastern region and central region of Taihu Lake is distorted by ANN model because of the limitations, such as learning target setting and over-learning in net construction. PMID:19558096

  18. [Monitoring of the Moskva River Water Using Microbiological Parameters and Chlorophyll a Fluorescence].

    PubMed

    Mosharova, I V; Il'inskii, V V; Matorin, D N; Mosharov, S A; Akulova, A Yu; Protopopov, F F

    2015-01-01

    The results of investigations of three Moskva River sites with different degree of pollution using a complex of microbiological characteristics and the parameters of chlorophyll a fluorescence are presented. We determined that the bacterioplankton seasonal dynamics at less polluted waters (Tushino and Vorobyovy Gory) were similar and differed significantly from one in more polluted waters (Dzerzhinskii). The number of bacteria with active electron transport chain, as well as their share in the bacterioplankton structure, was higher in the water of Dzerzhinskii (average annual values of 0.23 x 10(6) cells/mL and 14%), that in the less polluted water of Tushino and Vorobyovy Gory (0.14 x 10(6) cells/mL; 6% and 0.15 x 10(6) cells/mL; 7%, respectively). From April to October, the content of chlorophyll a and its photosynthetic activity were the highest in Tushino. In Dzerzhinskii, during spring the increase in photosynthetic activity commenced earlier and was more intensive that the increase in chlorophyll a content, i.e., the increase in phytoplankton biomass was temporarily suppressed. We suggest association of this phenomenon with suppression of organic matter synthesis by phytoplankton due to the high water pollution in Dzerzhinskii. The second autumn peak of chlorophyll a content, that was typical of clear water and was observed in Tushino, did not occur in Dzerzhinskii. We recommend combined application of these microbiological parameters and characteristics of chlorophyll a fluorescence for a monitoring. PMID:26964361

  19. The calculated in vitro and in vivo chlorophyll a absorption bandshape.

    PubMed Central

    Zucchelli, Giuseppe; Jennings, Robert C; Garlaschi, Flavio M; Cinque, Gianfelice; Bassi, Roberto; Cremonesi, Oliviero

    2002-01-01

    The room temperature absorption bandshape for the Q transition region of chlorophyll a is calculated using the vibrational frequency modes and Franck-Condon (FC) factors obtained by line-narrowing spectroscopies of chlorophyll a in a glassy (Rebane and Avarmaa, Chem. Phys. 1982; 68:191-200) and in a native environment (Gillie et al., J. Phys. Chem. 1989; 93:1620-1627) at low temperatures. The calculated bandshapes are compared with the absorption spectra of chlorophyll a measured in two different solvents and with that obtained in vivo by a mutational analysis of a chlorophyll-protein complex. It is demonstrated that the measured distributions of FC factors can account for the absorption bandshape of chlorophyll a in a hexacoordinated state, whereas, when pentacoordinated, reduced FC coupling for vibrational frequencies in the range 540-850 cm(-1) occurs. The FC factor distribution for pentacoordinated chlorophyll also describes the native chlorophyll a spectrum but, in this case, either a low-frequency mode (nu < 200 cm(-1)) must be added or else the 262-cm(-1) mode must increase in coupling by about one order of magnitude to describe the skewness of the main absorption bandshape. PMID:11751324

  20. Mixed layer depth and chlorophyll a: Profiling float observations in the Kuroshio-Oyashio Extension region

    NASA Astrophysics Data System (ADS)

    Itoh, Sachihiko; Yasuda, Ichiro; Saito, Hiroaki; Tsuda, Atsushi; Komatsu, Kosei

    2015-11-01

    Variability in the chlorophyll a concentration (Chl) in relation to fluctuations in the mixed layer (ML) was investigated together with turbidity (Tur) in the Kuroshio-Oyashio Extension region, using profiling floats. A particular focus was the validity of two hypotheses concerning the spring bloom: the critical depth hypothesis (CDH) and the recently proposed alternative, the disturbance-recovery hypothesis (DRH). During the period from winter to early spring, Chl and Tur integrated over the photosynthetically active layer (PL; defined as the greatest depth of the ML and the euphotic layer) increased with increasing PL depth (PLD), indicating an increase in the phytoplankton biomass. This result is partly consistent with the DRH in that the observed increase in biomass was not explained by an increase in production. Instead, it was more likely attributable to a reduction in the loss rate. However, theoretical analyses revealed that grazer dilution alone could not cause this increase in biomass because such an increase in the ML in the real ocean (as opposed to a dilution experiment within a bottle) would cause a reduction in the mean light intensity. Despite the loss-controlled fluctuation in biomass during the period of low light, a production-driven fluctuation in biomass was also revealed. This occurred when the light intensity was elevated, particularly after late spring, and was consistent with the CDH. Thus, the present study suggests that both the production-driven and loss-driven hypotheses are responsible for the dynamics of the phytoplankton dynamics from winter to spring in the Kuroshio-Oyashio Extension region.

  1. Four wavelength lidar applied to determination of chlorophyll a concentration and algae color group

    NASA Technical Reports Server (NTRS)

    Jarrett, O., Jr.; Mumola, P. B.; Brown, C. A., Jr.

    1973-01-01

    A technique for remote measurement of chlorophyll a density and determination of algae color group is described. In vivo fluorescence measurements of chlorophyll a for four color groups of algae (green, golden-brown, red, and blue-green) are described, and representative spectra are shown. The lidar equation is developed for the general case of a mixture of color groups showing the need for multicolor excitation. The lidar instrument which has been designed and fabricated at Langley Research Center for helicopter flights over surrounding portions of the Chesapeake Bay is described. The lidar package contains a unique four-color dye laser which permits multicolor excitation of chlorophyll a fluorescence from the various color groups of algae.

  2. Multiwavelength LIDAR for remote sensing of chlorophyll A in algae and phytoplankton

    NASA Technical Reports Server (NTRS)

    Mumola, P. B.; Jarrett, O., Jr.; Brown, C. A., Jr.

    1975-01-01

    A theoretical and experimental analysis of laser induced fluorescence for remote detection of chlorophyll A in living algae and phytoplankton is presented. The fluorescent properties of various species of algae representative of the different color groups are described. Laboratory measurements of fluorescent scattering cross sections is discussed and quantitive data presented. A scattering matrix model is developed to demonstrate the essential requirement of multiwavelength laser excitation in order to make accurate quantitative measurements of chlorophyll A concentration when more than one color group of algae is present in the water. A practical airborne laser fluorosensor design is considered and analysis of field data discussed. Successful operation of the Langley ALOPE (airborne LIDAR oceanographic probing experiment) system is described and field measurements presented. Accurate knowledge of alpha, the optical attenuation coefficient of the water, is shown to be essential for quantitative analysis of chlorophyll A concentration. The feasibility of remotely measuring alpha by laser radar is discussed.

  3. Defining suitable reference genes for RT-qPCR analysis on human sertoli cells after 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure.

    PubMed

    Ribeiro, Mariana Antunes; dos Reis, Mariana Bisarro; de Moraes, Leonardo Nazário; Briton-Jones, Christine; Rainho, Cláudia Aparecida; Scarano, Wellerson Rodrigo

    2014-11-01

    Quantitative real-time RT-PCR (qPCR) has proven to be a valuable molecular technique to quantify gene expression. There are few studies in the literature that describe suitable reference genes to normalize gene expression data. Studies of transcriptionally disruptive toxins, like tetrachlorodibenzo-p-dioxin (TCDD), require careful consideration of reference genes. The present study was designed to validate potential reference genes in human Sertoli cells after exposure to TCDD. 32 candidate reference genes were analyzed to determine their applicability. geNorm and NormFinder softwares were used to obtain an estimation of the expression stability of the 32 genes and to identify the most suitable genes for qPCR data normalization. PMID:25078986

  4. Spectral luminescence and photochemical properties of chlorophyll a in solution containing carbon tetrachloride

    SciTech Connect

    Gruzinskii, V.V.; Gurinovich, V.V.; Sagun, E.I.; Tsvirko, M.P.

    1987-08-01

    Studies were conducted on photophysical and photochemical processes in chlorophyll a in carbon tetrachloride and ether by means of flash photolysis, electron spin resonance, and fluorescence spectroscopy. Lifetimes and quenching of triplet states were analyzed and absorption spectra and fluorescence decay times are given. The kinetics of triplet-triplet absorption and hyperfine structure were determined. An absolute quantum yield of the photochemical reaction was measured within the range of linear dependence of the optical density on the time of chlorophyll a irradiation by a krypton laser and the excitation wavelength of 647.1 nm.

  5. Quantitative mapping of chlorophyll a distributions in coastal zones by remote sensing

    NASA Technical Reports Server (NTRS)

    Johnson, R. W.

    1977-01-01

    Results of experiments conducted in the James River, Virginia and the New York Bight indicate that concurrently collected sea-truth measurements may be used to calibrate remotely sensed multispectral scanner data collected over each of these environmentally different scenes. Statistical stepwise regression analysis was used in both experiments to incorporate significant bands of MSS data into regression equations that quantitatively relate remotely sensed data to water quality parameters, such as chlorophyll a and suspended sediment. These regression equations are used to map synoptic distributions of chlorophyll a in the remotely sensed scenes.

  6. Isolation of chlorophylls a and b from spinach by counter-current chromatography.

    PubMed

    Jubert, Carole; Bailey, George

    2007-01-26

    A method for the isolation of chlorophylls from spinach by counter-current chromatography was developed. An initial extraction protocol was devised to avoid the notorious sensitivity of chlorophylls to degradation by light, heat, oxygen, acids and bases. Further purification and separation of chlorophylls a and b were achieved using counter-current chromatography. Chlorophyll structures and purities were established by HPLC, fast atom bombardment mass spectrometry and nuclear magnetic resonance. Purity was estimated to be >95% (100% by HPLC). Typical yields from 30g of freeze-dried spinach were 300mg of chlorophyll a and 100mg of chlorophyll b. PMID:17164074

  7. Defining nutrient and biochemical oxygen demand baselines for tropical rivers and streams in São Paulo State (Brazil): a comparison between reference and impacted sites.

    PubMed

    Cunha, Davi G F; Dodds, Walter K; Carmo Calijuri, Maria do

    2011-11-01

    Determining reference concentrations in rivers and streams is an important tool for environmental management. Reference conditions for eutrophication-related water variables are unavailable for Brazilian freshwaters. We aimed to establish reference baselines for São Paulo State tropical rivers and streams for total phosphorus (TP) and nitrogen (TN), nitrogen-ammonia (NH(4) (+)) and Biochemical Oxygen Demand (BOD) through the best professional judgment and the trisection methods. Data from 319 sites monitored by the São Paulo State Environmental Company (2005 to 2009) and from the 22 Water Resources Management Units in São Paulo State were assessed (N = 27,131). We verified that data from different management units dominated by similar land cover could be analyzed together (Analysis of Variance, P = 0.504). Cumulative frequency diagrams showed that industrialized management units were characterized by the worst water quality (e.g. average TP of 0.51 mg/L), followed by agricultural watersheds. TN and NH(4) (+) were associated with urban percentages and population density (Spearman Rank Correlation Test, P < 0.05). Best professional judgment and trisection (median of lower third of all sites) methods for determining reference concentrations showed agreement: 0.03 & 0.04 mg/L (TP), 0.31 & 0.34 mg/L (TN), 0.06 & 0.10 mg-N/L (NH(4) (+)) and 2 & 2 mg/L (BOD), respectively. Our reference concentrations were similar to TP and TN reference values proposed for temperate water bodies. These baselines can help with water management in São Paulo State, as well as providing some of the first such information for tropical ecosystems. PMID:21858554

  8. CHLOROPHYLL A DISTRIBUTION IN NARRAGANSETT BAY, RI: USING A SPECTRAL CURVATURE ALGORITHM

    EPA Science Inventory

    Chlorophyll a, a primary indicator of eutrophication in estuarine waters, varies enough in time and space to create spatial problems when monitored by satellite, and temporal problems when measured with in situ field programs. Using aircraft to sense ocean color of local waters, ...

  9. Cross-system comparison of factors influencing chlorophyll-a concentration in Oregon estuaries

    EPA Science Inventory

    Water column chlorophyll-a (chla) is a proxy for phytoplankton biomass and is often used as a biological response indicator of eutrophication. Although watershed nutrient loading may influence chla concentration in estuaries, factors such as freshwater inflow, residence time, and...

  10. PREDICTING CONCENTRATION OF TOTAL PHOSPHORUS AND CHLOROPHYLL 'A' IN A LAKE WITH SHORT HYDRAULIC RESIDENCE TIME

    EPA Science Inventory

    The relationship between total phosphorus and chlorophyll a concentration was determined for Skinner Lake, Indiana over an annual cycle in 1978-79. Total nitrogen: total phosphorus ratios in the epilimnion ranged from 19 to 220 suggesting a phosphorus-dependent algal yield in the...

  11. Enhanced charge separation in chlorophyll a solar cell by gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Barazzouk, Saïd; Hotchandani, Surat

    2004-12-01

    An efficient organic photoelectrochemical cell based on chlorophyll a (Chla) and gold nanoparticles is constructed. The enhanced performance of this cell is due to the beneficial role of gold nanoparticles in accepting and shuttling the photogenerated electrons in Chla to the collecting electrode. This produces a long-distance charge-separated state, resulting into an enhancement in charge separation efficiency.

  12. Preparation of native and recombinant light-harvesting chlorophyll-a/b complex.

    PubMed

    Rühle, Wolfgang; Paulsen, Harald

    2011-01-01

    Procedures to isolate native light-harvesting chlorophyll-a/b complex (LHCIIb) and to reconstitute recombinant LHCIIb are described. Separation of trimeric from monomeric forms and free pigment by sucrose density-gradient ultracentrifugation can be applied to both native and reconstituted complexes. The preparations are characterized by their pigment composition, protein pattern, and spectral properties. PMID:20960126

  13. Preparation of native and recombinant light-harvesting chlorophyll-a/b complex.

    PubMed

    Rühle, Wolfgang; Paulsen, Harald

    2004-01-01

    Procedures to isolate native light-harvesting chlorophyll-a/b complex (LHCIIb) and to reconstitute recombinant LHCIIb are described. Separation of trimeric from monomeric forms and free pigment by sucrose density-gradient ultracentrifugation can be applied to both native and reconstituted complexes. The preparations are characterized by their pigment composition, protein pattern and spectral properties. PMID:15187272

  14. Effect of discharge on the chlorophyll a distribution in the tidally-influenced Potomac River

    USGS Publications Warehouse

    Bennett, J.P.; Woodward, J.W.; Shultz, D.J.

    1986-01-01

    In the tidal Potomac River, high river discharges during the spring are associated with high chlorophyll a concentrations in the following in the following summer, assuming that summertime light and temperature conditions are favorable. Spring floods deliver large loads of particulate N and P to the tidal river. This particulate N and P could be mineralized by bacteria to inorganic N and P and released to the water column where it is available for phytoplankton use during summertime. However, during the study period relatively low concentrations of chlorophyll a (less than 50 ??g l-1 occurred in the tidal river if average monthly discharge during July or August exceeded 200 m3s-1. Discharge and other conditions combined to produce conditions favorable for nuisance levels of chlorophyll a (greater than 100 ??g l-1 approximately one year out of four. Chlorophyll a maxima occurred in the Potomac River transition zone and estuary during late winter (dinoflagellates) and spring (diatoms). Typical seasonal peak concentrations were achieved at discharges as high as 970 m3 s-1, but sustained discharges greater than 1,100 m3 s-1 retarded development. Optimum growth conditions occurred following runoff events of 10 to 15 d duration which produced transit times to the transition zone of 7 to 10 d. Wet years with numerous moderate-sized runoff events, such as 1980, tend to produce greater biomass in the transition zone and estuary than do dry years such as 1981. ?? 1986 Estuarine Research Federation.

  15. Algae (Microcystis and Scenedesmus) absorption spectra and its application on Chlorophyll a retrieval

    NASA Astrophysics Data System (ADS)

    Wu, Di; Chen, Maosi; Wang, Qiao; Gao, Wei

    2013-12-01

    Blue algae and green algae are the dominant phytoplankton groups that contribute to the eutrophication and the water bloom in inland water of China. The absorption coefficients (spectra) of the algae, which do not change with its intrinsic optical characteristics and the observation geometry, are strictly additive quantities. The characteristics of the absorption spectra of the two algae are presented. The pure blue algae and the pure green algae cultured in the laboratory environment are diluted and mixed at ten volume ratios. The Quantitative Filter Technique was applied to measure their absorption spectra. The "hot-ethanol extraction" method was chosen to calculate their concentration of Chlorophyll a. The retrieval algorithm developed in this study extracts the mapping information between each individual alga and their Chlorophyll a concentration via Continuous Wavelet Transform, and retrieves the Chlorophyll a concentration of each alga in their mixture using a trust region optimizer. The results show that the retrieved and the measured Chlorophyll a concentrations of the blue algae and the green algae components in the ten mixture match well with the average relative error of 5.55%.

  16. Technological applications of chlorophyll a fluorescence for the assessment of environmental pollutants.

    PubMed

    Buonasera, K; Lambreva, M; Rea, G; Touloupakis, E; Giardi, M T

    2011-09-01

    Chlorophyll a fluorescence has been extensively studied over the last few years. As demonstrated, this phenomenon is closely related to the state of photosystem II, which plays a leading role in the photosynthetic process, and therefore it has become a powerful tool to investigate this complex and any damage occurring in it as a result of physical or chemical stresses. This means that by using photosynthetic organisms as biological probes, one can consider chlorophyll a fluorescence as one of the techniques of choice to reveal the presence of some hazardous toxicants widely spread in the environment. Herbicides, pesticides, and heavy metals, whose concentration in water and food products is generally subject to extremely severe restrictions, are a concrete example of compounds detectable by chlorophyll a fluorescence. These dangerous substances react with the photosystem II, modifying the fluorescence emitted and giving responses which vary in a concentration-dependent manner. The possibility of performing easy, fast, and direct measurements of the fluorescence, even under light conditions, has opened new frontiers for the analysis in situ of pollutants. The aim of this review is to give an overview of the different techniques based on chlorophyll a fluorescence spectrometry, focusing in particular on those which represented the starting point for applications addressed to the assessment of toxic compounds in environmental samples. PMID:21701849

  17. Isolation and Characterization of a Light-Harvesting Chlorophyll a/b Protein Complex Associated with Photosystem I 1

    PubMed Central

    Lam, Eric; Oritz, William; Mayfield, Stephen; Malkin, Richard

    1984-01-01

    A chlorophyll a/b protein complex has been isolated from a resolved native photosystem I complex by mildly dissociating sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The chlorophyll a/b protein contains a single polypeptide of molecular weight 20 kilodaltons, and has a chlorophyll a/b ratio of 3.5 to 4.0. The visible absorbance spectrum of the chlorophyll a/b protein complex showed a maximum at 667 nanometers in the red region and a 77 K fluorescence emission maximum at 681 nanometers. Alternatively, by treatment of the native photosystem I complex with lithium dodecyl sulfate and Triton, the chlorophyll a/b protein complex could be isolated by chromatography on Sephadex G-75. Immunological assays using antibodies to the P700-chlorophyll a-protein and the photosystem II light-harvesting chlorophyll a/b protein show no cross-reaction between the photosystem I chlorophyll a/b protein and the other two chlorophyll-containing protein complexes. Images Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:16663476

  18. Variability of satellite derived chlorophyll-a in the southern Caspian Sea following an invasion of ctenophore Mnemiopsis leidyi

    NASA Astrophysics Data System (ADS)

    Moradi, Masoud

    2013-01-01

    The comb jellyfish Mnemiopsis leidyi invaded vastly the whole Caspian Sea in summer 2001. Sea-viewing wide field-of-view sensor and moderate resolution imaging spectroradiometer (MODIS) satellite data from 1998 to 2006 and bio-optical field measurements along six transects in the southern Caspian Sea from 2001 to 2006 were used to detect the relationships between M. leidyi abundances with satellite driven sea surface temperature (SST) and chlorophyll-a. MODIS chlorophyll-a and SST monthly composite average value showed a positive linear correlation with M. leidyi abundance in the southern Caspian Sea. Spatiotemporal distribution of MODIS chlorophyll-a high-level patches (˜5 mg.m-3) were also confirmed with the highest recorded M. leidyi and the lowest zooplankton abundances. However, there are several other factors that affect the concentration of chlorophyll-a, and it is not clear how much of the chlorophyll-a variation is related to M. leidyi abundances.

  19. The Characterization of Chlorophyll-A and Microalgae Isolation Process of Wastewater Collected at Sembrong Dam

    NASA Astrophysics Data System (ADS)

    Wellson, R.; Othman, N.; Matias-Peralta, H. M.

    2016-07-01

    Recently, there has been an increasing number of river water quality deterioration that has brought into water quality disruptions that entering dams including in Johor and one of them is occurred in Sembrong Dam in Johor. Sembrong Dam is a major water source for some 120,000 people in the districts of Kluang and parts of Batu Pahat. The quality of water in Sembrong should be well-monitored in ensuring the continuous distribution of clean and safe water supply to peoples. Based on the news reported by The Star news dated on 11 May 2015, the water bodies in Sembrong Dam are polluted by the algae blooms which has started to cause problems in treating water phase by clogging up the filters and causing the production to be reduced and finally resulting in frequent water disruptions to residents. Therefore, there is a need to study the water quality of the dam water prior to further water treatment. One of important characterizations is by measuring chlorophyll-a and the isolation of the dominant microalgae species in the water body in which they are able to indicate the level of water pollution. This paper presents the determination of chlorophyll-a and the isolation of microalgae strains collected from Sembrong Dam. Chlorophyll-a is a photosynthetic pigment present in all species of phytoplankton, including algae and in some photosynthetic bacteria, known as cyanobacteria. The method used in measuring the chlorophyll-a is based on the standard method of IS0 10 260. The average chlorophyll-a concentration measured at Sembrong Dam is 175.9 µg L-1 and it is responsible for the appearance of green color in the sample and it is categorized into hypereutrophic state which is highly polluted. The technique used for isolation of microalgae strains is traditional method which is by spreading the sample on agar. The pure isolate indicated that the genus Botryococcus is the dominant algae species which is characterized morphologically. Both chlorophyll-a and microalgae

  20. IO columns and the relation to chlorophyll-a as observed from satellite

    NASA Astrophysics Data System (ADS)

    Schönhardt, A.; Richter, A.; Burrows, J. P.

    2012-04-01

    Halogens and their oxides are important for atmospheric composition. In the troposphere, relevance of iodine is linked to the depletion of ozone, the alteration of the HOx and NOx ratios, and the formation of new atmospheric particles. The release pathways, relations and implications of atmospheric iodine are currently being investigated by means of field measurements, satellite observations, laboratory studies and modeling activities. Some biogenic sources of iodine such as from algae and phytoplankton have been identified, however, their overall importance, relative and absolute, is not yet clarified. This presentation concentrates on measurements of iodine monoxide (IO) from satellite, their analysis and interpretation. Using a long term data set of up to 8 years signal quality can be improved by suitable temporal averaging. Applying basic radiative transfer, IO vertical columns are computed in spite of unknowns such as the IO vertical profile. The retrieval of IO, its challenges, and the air mass factor calculations are explained. In order to investigate the relation between biological activity and IO, chlorophyll-a concentrations in the oceans are compared to IO maps. For these comparisons, observations from the SCIAMACHY and SeaWiFS sensors are used. Especially interesting regions are the ocean upwelling areas, where biology is active, and emissions of biogenic compounds to the atmosphere take place. Observation of IO above water bodies is challenging as the present amounts are close to the detection limit, and absolute amounts need to be treated with care. The application of a large IO satellite data set improves this situation to some extent. Largest amounts of wide spread enhanced IO are found around the Antarctic, an area where chlorophyll-a concentrations in the Southern Ocean reveal a similar spatial pattern as IO. Above the sea ice, where chlorophyll-a measurements are not possible, IO appears mainly in late spring time, when the ice porousness and

  1. Abundance of a chlorophyll a precursor and the oxidation product hydroxychlorophyll a during seasonal phytoplankton community progression in the Western English Channel

    NASA Astrophysics Data System (ADS)

    Steele, Deborah J.; Tarran, Glen A.; Widdicombe, Claire E.; Woodward, E. Malcolm S.; Kimmance, Susan A.; Franklin, Daniel J.; Airs, Ruth L.

    2015-09-01

    This study presents the first in-situ measurements of the chlorophyll a oxidation product, hydroxychlorophyll a as well as the chlorophyll a precursor, chlorophyll aP276 conducted over an annual cycle. Chlorophyll a oxidation products, such as hydroxychlorophyll a may be associated with the decline of algal populations and can act as an initial step in the degradation of chlorophyll a into products which can be found in the geochemical record, important for studying past climate change events. Here, hydroxychlorophyll a and chlorophyll aP276 were measured at the long-term monitoring station L4, Western Channel Observatory (UK, http://www.westernchannelobservatory.org)

  2. The optimal hyperspectral quantitative models for chlorophyll-a of chlorella vulgaris

    NASA Astrophysics Data System (ADS)

    Cheng, Qian; Wu, Xiuju

    2009-09-01

    Chlorophyll-a of Chlorella vulgaris had been related with spectrum. Based on hyperspectral measurement for Chlorella vulgaris, the hyperspectral characteristics of Chlorella vulgaris and their optimal hyperspectral quantitative models of chlorophyll-a (Chla) estimation were researched in situ experiment. The results showed that the optimal hyperspectral quantitative model of Chlorella vulgaris was Chla=180.5+1125787(R700)'+2.4 *109[(R700)']2 (P0<.01), and the suitability order of corresponding methods was spectral ratio

  3. [A Three Band Chlorophyll-a Concentration Estimation Model Based on GOCI Imagery].

    PubMed

    Guo, Yu-long; Li, Yun-mei; Li, Yuan; Lü, Heng; Liu, Ge; Wang, Xu-dong; Zhang, Si-min

    2015-09-01

    A GOCI-based three band model is proposed for chlorophyll-a concentration estimation based on the classical three band model. The model was built based on 289 in-situ measured chlorophyll-a concentration and hyperspectral spectrums-simulated GOCI spectrums, and was compared with MERIS-based three band model and GOCI band ratio model. At last, the model was validated using several GOCI images and an independent in-situ sampling dataset. The results showed that: (1) For the current dataset, the ratio of aph (680) and aph (660) was relatively stable. (2) The GOCI-based three band algorithm had a similar performance with MERIS-based three band algorithm in the modeling dataset. The R2 value of the GOCI-based three band model was 0. 809, which was a little lower than that of the MERIS-based three band model (R2 = 0. 820), but was obviously higher than that of GOCI band ratio model (R2 = 0. 450). (3) The performance of GOCI-based three band model in the validation dataset was similar with that in the modeling dataset, which was close to that of the MERIS-based three band model, and significantly better than that of GOCI band ratio model. (4) The GOCI image data validation indicated that GOCI band ratio model would clearly underestimate chlorophyll-a concentration in Taihu Lake. The spatial difference of chlorophyll-a concentration that yielded by the band ratio model was not clear. Compared with the widely used band ratio algorithm, the GOCI-based three band algorithm has higher stability, better accuracy, and stronger potential in application. PMID:26717676

  4. Did sulfate availability facilitate the evolutionary expansion of chlorophyll a+c phytoplankton in the oceans?

    PubMed

    Ratti, S; Knoll, A H; Giordano, M

    2011-07-01

    During the Mesozoic Era, dinoflagellates, coccolithophorids and diatoms became prominent primary producers in the oceans, succeeding an earlier biota in which green algae and cyanobacteria had been proportionally more abundant. This transition occurred during an interval marked by increased sulfate concentration in seawater. To test whether increasing sulfate availability facilitated the evolutionary transition in marine phytoplankton, the cyanobacterium Synechococcus sp., the green alga Tetraselmis suecica and three algae containing chlorophyll a+c (the diatom Thalassiosira weissflogii, the dinoflagellate Protoceratium reticulatum and the coccolithophorid Emiliania huxleyi) were grown in media containing 1, 5, 10, 20, or 30 mm SO(4) (2-) . The cyanobacterium and the green alga showed no growth response to varying [SO(4) (2-) ]. By contrast, the three chlorophyll a+c algae showed improved growth with higher [SO(4) (2-) ], but only up to 10 mm. The chlorophyll a+c algae, but not the green alga or cyanobacterium, also showed lower C:S with higher [SO(4) (2-) ]. When the same experiment was repeated in the presence of a ciliate predator (Euplotes sp.), T. suecica and T. weissflogii increased their specific growth rate in most treatments, whereas the growth rate of Synechococcus sp. was not affected or decreased in the presence of grazers. In a third experiment, T. suecica, T. weissflogii, P. reticulatum and Synechococcus sp. were grown in conditions approximating modern, earlier Paleozoic and Proterozoic seawater. In these treatments, sulfate availability, nitrogen source, metal availability and Pco(2) varied. Monospecific cultures exhibited their highest growth rates in the Proterozoic treatment. In mixed culture, T. weissflogii outgrew other species in modern seawater and T.suecica outgrew the others in Paleozoic water. Synechococcus sp. grew best in Proterozoic seawater, but did not outgrow eukaryotic species in any treatment. Collectively, our results suggest that

  5. Monolayers and multilayers of chlorophyll [correction of chlorophyl] a on a mercury electrode.

    PubMed

    Moncelli, M R; Becucci, L; Dolfi, A; Tadini Buoninsegni, F; Agostiano, A

    2002-05-15

    A novel experimental technique used to investigate chlorophyll films on a hanging mercury drop electrode is described. Two different procedures are employed to prepare self-assembled chlorophyll monolayers and multilayers on the mercury electrode. Upon illuminating the chlorophyll a (Chl)-coated mercury electrode with an appropriate light source, the photocurrents generated by the Chl aggregates are measured under short-circuit conditions in the absence of photoartefacts. The preliminary results obtained by this novel technique are presented. PMID:12009465

  6. Crystal Structure and Catalytic Mechanism of 7-Hydroxymethyl Chlorophyll a Reductase.

    PubMed

    Wang, Xiao; Liu, Lin

    2016-06-17

    7-Hydroxymethyl chlorophyll a reductase (HCAR) catalyzes the second half-reaction in chlorophyll b to chlorophyll a conversion. HCAR is required for the degradation of light-harvesting complexes and is necessary for efficient photosynthesis by balancing the chlorophyll a/b ratio. Reduction of the hydroxymethyl group uses redox cofactors [4Fe-4S] cluster and FAD to transfer electrons and is difficult because of the strong carbon-oxygen bond. Here, we report the crystal structure of Arabidopsis HCAR at 2.7-Å resolution and reveal that two [4Fe-4S]clusters and one FAD within a very short distance form a consecutive electron pathway to the substrate pocket. In vitro kinetic analysis confirms the ferredoxin-dependent electron transport chain, thus supporting a proton-activated electron transfer mechanism. HCAR resembles a partial reconstruction of an archaeal F420-reducing [NiFe] hydrogenase, which suggests a common mode of efficient proton-coupled electron transfer through conserved cofactor arrangements. Furthermore, the trimeric form of HCAR provides a biological clue of its interaction with light-harvesting complex II. PMID:27072131

  7. Algal photosynthetic responses to toxic metals and herbicides assessed by chlorophyll a fluorescence.

    PubMed

    Kumar, K Suresh; Dahms, Hans-Uwe; Lee, Jae-Seong; Kim, Hyung Chul; Lee, Won Chan; Shin, Kyung-Hoon

    2014-06-01

    Chlorophyll a fluorescence is established as a rapid, non-intrusive technique to monitor photosynthetic performance of plants and algae, as well as to analyze their protective responses. Apart from its utility in determining the physiological status of photosynthesizers in the natural environment, chlorophyll a fluorescence-based methods are applied in ecophysiological and toxicological studies to examine the effect of environmental changes and pollutants on plants and algae (microalgae and seaweeds). Pollutants or environmental changes cause alteration of the photosynthetic capacity which could be evaluated by fluorescence kinetics. Hence, evaluating key fluorescence parameters and assessing photosynthetic performances would provide an insight regarding the probable causes of changes in photosynthetic performances. This technique quintessentially provides non-invasive determination of changes in the photosynthetic apparatus prior to the appearance of visible damage. It is reliable, economically feasible, time-saving, highly sensitive, versatile, accurate, non-invasive and portable; thereby comprising an excellent alternative for detecting pollution. The present review demonstrates the applicability of chlorophyll a fluorescence in determining photochemical responses of algae exposed to environmental toxicants (such as toxic metals and herbicides). PMID:24632123

  8. Seasonal variation of nitrogen, phosphorus, and chlorophyll a in Lake Michigan and Green Bay, 1965

    USGS Publications Warehouse

    Allen, Herbert Ellis

    1973-01-01

    Total and dissolved phosphorus, nitrate, and chlorophyll a were measured at four stations in northern Lake Michigan (inshore Michigan, offshore Michigan, offshore Wisconsin, and inshore Wisconsin) and one station in southern Green Bay during 16 sampling periods in 1965. The nutrients were measured at depths of 2, 5, and 10 meters and chlorophyll a at 2 meters. In Green Bay total phosphorus (33.7 ppb) was about five times as high and dissolved phosphorus (7.0 ppb) more than twice as high as the averages for the four Lake Michigan stations, but nitrate nitrogen concentration (37.3 ppb) was only about onethird that in the lake. Total and dissolved phosphorus were about 50 percent higher in the inshore Michigan area than in the other three lake areas. Concentration and seasonal trends in nitrates differed relatively little among the four lake stations. Nitrate at all areas and depths sampled decreased to almost nondetectable levels during September. Chlorophyll a was 70 percent higher at the two inshore areas than at the two offshore areas in the lake and was more than four times higher in Green Bay than at any lake area.

  9. Development of ocean color algorithms for estimating chlorophyll-a concentrations and inherent optical properties using gene expression programming (GEP).

    PubMed

    Chang, Chih-Hua

    2015-03-01

    This paper proposes new inversion algorithms for the estimation of Chlorophyll-a concentration (Chla) and the ocean's inherent optical properties (IOPs) from the measurement of remote sensing reflectance (Rrs). With in situ data from the NASA bio-optical marine algorithm data set (NOMAD), inversion algorithms were developed by the novel gene expression programming (GEP) approach, which creates, manipulates and selects the most appropriate tree-structured functions based on evolutionary computing. The limitations and validity of the proposed algorithms are evaluated by simulated Rrs spectra with respect to NOMAD, and a closure test for IOPs obtained at a single reference wavelength. The application of GEP-derived algorithms is validated against in situ, synthetic and satellite match-up data sets compiled by NASA and the International Ocean Color Coordinate Group (IOCCG). The new algorithms are able to provide Chla and IOPs retrievals to those derived by other state-of-the-art regression approaches and obtained with the semi- and quasi-analytical algorithms, respectively. In practice, there are no significant differences between GEP, support vector regression, and multilayer perceptron model in terms of the overall performance. The GEP-derived algorithms are successfully applied in processing the images taken by the Sea Wide Field-of-view Sensor (SeaWiFS), generate Chla and IOPs maps which show better details of developing algal blooms, and give more information on the distribution of water constituents between different water bodies. PMID:25836776

  10. The effects of variability in the inherent optical properties on estimations of chlorophyll a by remote sensing in Swedish freshwaters.

    PubMed

    Strömbeck, N; Pierson, D C

    2001-03-14

    During late summer of 1997 measurements were made of the inherent optical properties in Lake Mälaren, Sweden. These included measurements of the total particulate absorption, phytoplankton absorption, yellow substance absorption and total backscattering. Measurements were also made of concentrations known to affect the inherent optical properties; chlorophyll a and suspended particulate organic and inorganic matter. At the same time measurements of underwater radiance reflectance were made. The above measurements were used to better define the relationships between the inherent optical properties and the concentrations affecting them. Correlation analyses were also made in order to study covariation of the concentrations of suspended and dissolved substances in the data set. These relationships were then used to better parameterize a semi-analytical model predicting remote sensing reflectance. Multivariate sensitivity analyses showed that large variations on the Rr(700-710)/Rr(678-685) ratio vs. chlorophyll concentrations could be expected in a heterogeneous environment such as Lake Mälaren. This could lead to large errors in subsequent estimates of chlorophyll concentrations. PMID:11315736

  11. Investigation of the spectra of luminescence and Raman scattering in water and chlorophyll "a" excited by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Biryukova, Yu. S.; Ilyin, A. A.; Golik, S. S.; Mayor, A. Y.

    2015-11-01

    The Raman spectra of femtosecond laser pulses in distilled and tap water, and luminescence spectra of aqueous solutions containing dissolved organic matter, chlorophyll "a" and biological objects excited by ultra-short laser pulses was investigated.

  12. Spatiotemporal chlorophyll-a dynamics on the Louisiana continental shelf derived from a dual satellite imagery algorithm

    EPA Science Inventory

    A monthly time series of remotely sensed chlorophyll-a (Chlars) over the Louisiana continental shelf (LCS) was developed and examined for its relationship to river discharge, nitrate concentration, total phosphorus concentration, photosynthetically available radiation (PAR), wind...

  13. Patterns of distribution and environmental correlates of macroalgal assemblages and sediment chlorophyll a in Oregon tidal wetlands

    EPA Science Inventory

    Algae have important functional roles in estuarine wetlands along the Pacific coast of the United States. We quantified differences in macroalgal abundance, composition and diversity, and sediment chlorophyll a and pheophytin a among three National Wetlands Inventory emergent mar...

  14. Direct observation of energy transfer in a photosynthetic membrane: Chlorophyll b to chlorophyll a transfer in LHC

    SciTech Connect

    Eads, D.D.; Castner, E.W. Jr.; Alberte, R.S.; Mets, L.; Fleming, G.R. )

    1989-12-28

    Subpicosecond fluorescence upconversion has been used to measure the rate of chlorophyll b to chlorophyll a electronic energy transfer in situ within the LHC pigment proteins of Chlamydomonas reinhardtii mutant C2. The time scale of energy transfer is 0.5 {plus minus} 0.2 ps as determined from the rise time of chlorophyll a fluorescence following chlorophyll b excitation. Estimates of the energy-transfer rate based on Foerster weak coupling theory are discussed.

  15. From Surface Chlorophyll a to Phytoplankton Community Composition in Oceanic Waters

    NASA Technical Reports Server (NTRS)

    Uitz, Julia; Claustre, Herve; Morel, Andre; Hooker, Stanford B.

    2004-01-01

    The objective of the present study is to examine the potential of using the near-surface total chlorophyll a concentration (C(sub surf)), as it can be derived from ocean color observation, to infer the column-integrated and the vertical distribution of the phytoplanktonic biomass, both in a quantitative way and in a qualitative way (z.e., in terms of community structure). Within this context, a large HPLC (High Performance Liquid Chromatography) pigment database has been analyzed. It includes 2419 vertical pigment profiles, all sampled in Case-1 waters with various trophic states. The relationshps between C(sub surf) and the total chlorophyll alpha vertical distribution, as previously derived by Morel and Berthon, are fully confirmed, as the present results coincide with the previous ones. This agreement allows to go further, namely to examine the possibility of extracting relationships between C(sub surf) and the vertical composition of the algal assemblages. Thanks to the detailed pigment composition available from HPLC measurements, the contribution of three size classes (micro-, nano-, and pico-phytoplankton) to the local total chlorophyll a concentration can be assessed. Corroborating previous findings (e.g., large species dominate in eutrophc environments, whereas tiny phytoplankton prevail in oligotrophic zones), the results lead to a statistically based parameterization. The predictive skill of this parameterization is successfully tested on a separate data set. With such a tool, the vertical total chlorophyll a profiles associated with each size class can be inferred from the sole knowledge of C(sub surf). By combining this tool with satellite ocean color data, it becomes conceivable to quantify on a global scale the phytoplankton biomass associated with each of the three size classes.

  16. Comparative study of resonance Raman and surface-enhanced resonance Raman chlorophyll a spectra using soret and red excitation

    SciTech Connect

    Thomas, L.L.; Kim, Jaeho; Cotton, T.M. )

    1990-12-05

    Surface-enhanced resonance Raman scattering (SERRS) spectra are reported for chlorophyll a adsorbed on a silver electrode at 298 and 77 K with 406.7-, 457.9-, 514.5-, and 647.1-nm excitation. Submerging the electrode in degassed water at 298 K was found to improve the spectral quality by minimizing sample heating and photooxidation. Spectral intensities and peak resolutions were greater at all excitation wavelengths at liquid nitrogen temperature. Most significantly, roughened silver at the low temperature quenched the fluorescence accompanying red excitation and minimized sample photooxidation, resulting in richly detailed SERRS spectra of chlorophyll a. The close correspondence between chlorophyll a resonance Raman (RR) and SERRS spectra suggests that an electromagnetic mechanism is the major source of the surface enhancement, rather than a chemical mechanism (e.g. a charge-transfer complex between chlorophyll a and the metal). The spectral similarities, together with the presence of the MgN{sub 4} vibration band in the SERRS spectra, also provide evidence that structural alterations (e.g. cleavage of ring V or loss of Mg) do not occur in chlorophyll a after adsorption at the electrode surface. A distinctive SERRS spectrum was obtained for each excitation wavelength. Selective excitation within the various electronic transitions can thus be utilized to verify assignments of the vibrational modes of chlorophyll a and to monitor its interactions and photochemical behavior in biomimetic systems.

  17. Validation of SeaWiFS chlorophyll a in Massachusetts Bay

    NASA Astrophysics Data System (ADS)

    Hyde, Kimberly J. W.; O'Reilly, John E.; Oviatt, Candace A.

    2007-07-01

    Massachusetts Bay, a semi-enclosed embayment (50×100 km) in the Northwest Atlantic, is the focus of a monitoring program designed to measure the effects of relocating the Boston Harbor sewage outfall to a site 15 km offshore in Massachusetts Bay. The Massachusetts Water Resources Authority (MWRA) in situ monitoring program samples selected stations up to 17 times per year to observe seasonal changes in phytoplankton biomass and other water quality variables. We investigated the feasibility of augmenting the monitoring data with satellite ocean color data to increase the spatial and temporal resolution of quantitative phytoplankton measurements. In coastal regions such as Massachusetts Bay, ocean color remote sensing can be complicated by in-water constituents whose concentrations vary independently of phytoplankton and by inaccurate modeling of absorbing aerosols that tend to be concentrated near the coast. An evaluation of in situ and sea-viewing wide field-of-view sensor (SeaWiFS) measurements from 1998 to 2005 demonstrated that SeaWiFS overestimated chlorophyll a mainly due to atmospheric correction errors that were amplified by absorption from elevated concentrations of chlorophyll a and colored dissolved organic matter. Negative water-leaving radiances in the 412 nm band, an obvious artifact of inadequate atmospheric correction, were recorded in approximately 60-80% of the cloud-free images along the coast, while the remaining portions of the Bay only experience negative radiances 35-55% of the time with a clear nearshore to offshore decrease in frequency. Seasonally, the greatest occurrences of negative 412 nm radiances were in November and December and the lowest were recorded during the summer months. Concentrations of suspended solids in Massachusetts Bay were low compared with other coastal regions and did not have a significant impact on SeaWiFS chlorophyll a measurements. A regional empirical algorithm was developed to correct the SeaWiFS data to agree

  18. The Unique Photophysical Properties of the Peridinin-Chlorophyll-a-Protein

    PubMed Central

    Carbonera, Donatella; Valentin, Marilena Di; Spezia, Riccardo; Mezzetti, Alberto

    2014-01-01

    Peridinin-Chlorophyll-a-Proteins (PCPs) are water-soluble light harvesting complexes from dinoflagellates. They have unique light-harvesting and energy transfer properties which have been studied in details in the last 15 years. This review aims to give an overview on all the main aspects of PCPs photophysics, with an emphasis on some aspects which have not been reviewed in details so far, such as vibrational spectroscopy studies, theoretical calculations, and magnetic resonance studies. A paragraph on the present development of PCPs towards technological applications is also included. PMID:24678668

  19. Assessment of predictive models for chlorophyll-a concentration of a tropical lake

    PubMed Central

    2011-01-01

    Background This study assesses four predictive ecological models; Fuzzy Logic (FL), Recurrent Artificial Neural Network (RANN), Hybrid Evolutionary Algorithm (HEA) and multiple linear regressions (MLR) to forecast chlorophyll- a concentration using limnological data from 2001 through 2004 of unstratified shallow, oligotrophic to mesotrophic tropical Putrajaya Lake (Malaysia). Performances of the models are assessed using Root Mean Square Error (RMSE), correlation coefficient (r), and Area under the Receiving Operating Characteristic (ROC) curve (AUC). Chlorophyll-a have been used to estimate algal biomass in aquatic ecosystem as it is common in most algae. Algal biomass indicates of the trophic status of a water body. Chlorophyll- a therefore, is an effective indicator for monitoring eutrophication which is a common problem of lakes and reservoirs all over the world. Assessments of these predictive models are necessary towards developing a reliable algorithm to estimate chlorophyll- a concentration for eutrophication management of tropical lakes. Results Same data set was used for models development and the data was divided into two sets; training and testing to avoid biasness in results. FL and RANN models were developed using parameters selected through sensitivity analysis. The selected variables were water temperature, pH, dissolved oxygen, ammonia nitrogen, nitrate nitrogen and Secchi depth. Dissolved oxygen, selected through stepwise procedure, was used to develop the MLR model. HEA model used parameters selected using genetic algorithm (GA). The selected parameters were pH, Secchi depth, dissolved oxygen and nitrate nitrogen. RMSE, r, and AUC values for MLR model were (4.60, 0.5, and 0.76), FL model were (4.49, 0.6, and 0.84), RANN model were (4.28, 0.7, and 0.79) and HEA model were (4.27, 0.7, and 0.82) respectively. Performance inconsistencies between four models in terms of performance criteria in this study resulted from the methodology used in measuring

  20. Chlorophyll-a thin layers in the Magellan fjord system: The role of the water column stratification

    NASA Astrophysics Data System (ADS)

    Ríos, Francisco; Kilian, Rolf; Mutschke, Erika

    2016-08-01

    Fjord systems represent hotspots of primary productivity and organic carbon burial. However, the factors which control the primary production in mid-latitude fjords are poorly understood. In this context, results from the first fine-scale measurements of bio-oceanographic features in the water column of fjords associated with the Strait of Magellan are presented. A submersible fluorescence probe (FP) was used to measure the Chlorophyll-a (Chl-a) concentration in situ, along with conductivity, temperature, hydrostatic pressure (depth) and dissolved oxygen (CTD-O2) of the water column. The Austral spring results of 14 FP-CTD-O2 profiles were used to define the vertical and horizontal patches of the fluorescent pigment distribution and their spatial relations with respect to the observed hydrographic features. Three zones with distinct water structures were defined. In all zones, the 'brown' spectral group (diatoms and dinoflagellates) predominated accounting for >80 wt% of the phytoplankton community. Thin layers with high Chl-a concentration were detected in 50% of the profiles. These layers harbored a substantial amount (30-65 wt%) of the phytoplankton biomass. Stratification was positively correlated to the occurrence of Chl-a thin layers. In stable and highly stratified water columns the integrated Chl-a concentration was higher and frequently located within thin layers whereas well mixed water columns displayed lower values and more homogeneous vertical distribution of Chl-a. These results indicate that mixing/stability processes are important factors accounting to the vertical distribution of Chl-a in Magellan fjords.

  1. Spectral characterization in a supersonic beam of neutral chlorophyll a evaporated from spinach leaves

    NASA Astrophysics Data System (ADS)

    Shafizadeh, N.; Ha-Thi, M. H.; Soep, B.; Gaveau, M. A.; Piuzzi, F.; Pothier, C.

    2011-09-01

    The observation of the light absorption of neutral biomolecules has been made possible by a method implemented for their preparation in the gas phase, in supersonically cooled molecular beams, based upon the work of Focsa et al. [C. Mihesan, M. Ziskind, B. Chazallon, E. Therssen, P. Desgroux, S. Gurlui, and C. Focsa, Appl. Surf. Sci. 253, 1090 (2006)], 10.1016/j.apsusc.2006.01.082. The biomolecules diluted in frozen water solutions are entrained in the gas plume of evaporated ice generated by an infrared optical parametric oscillators (OPO) laser tuned close to its maximum of absorption, at ˜3 μm. The biomolecules are then picked up in the flux of a supersonic expansion of argon. The method was tested with indole dissolved in water. The excitation spectrum of indole was found cold and large clusters of indole with water were observed up to n = 75. Frozen spinach leaves were examined with the same method to observe the chlorophyll pigments. The Qy band of chlorophyll a has been observed in a pump probe experiment. The Qy bands of chlorophyll a is centred at 647 nm, shifted by 18 nm from its position in toluene solutions. The ionization threshold could also be determined as 6.1 ± 0.05 eV.

  2. Toxicological effects of chlorpyrifos on growth, enzyme activity and chlorophyll a synthesis of freshwater microalgae.

    PubMed

    Chen, Shangchao; Chen, Mindong; Wang, Zhuang; Qiu, Weijian; Wang, Junfeng; Shen, Yafei; Wang, Yajun; Ge, Shun

    2016-07-01

    This paper aims to acquire the experimental data on the eco-toxicological effects of agricultural pollutants on the aquatic plants and the data can support the assessment of toxicity on the phytoplankton. The pesticide of Chlorpyrifos used as a good model to investigate its eco-toxicological effect on the different microalgae in freshwater. In order to address the pollutants derived from forestry and agricultural applications, freshwater microalgae were considered as a good sample to investigate the impact of pesticides such as Chlorpyrifos on aquatic life species. Two microalgae of Chlorella pyrenoidosa and Merismopedia sp. were employed to evaluate toxicity of Chlorpyrifos in short time and long time by means of measuring the growth inhibition rate, the redox system and the content of chlorophyll a, respectively. In this study, the results showed that EC50 values ranging from 7.63 to 19.64mg/L, indicating the Chlorpyrifos had a relatively limited to the growth of algae during the period of the acute toxicity experiment. Moreover, when two kinds of algae were exposed to a medium level of Chlorpyrifos, SOD and CAT activities were importantly advanced. Therefore, the growth rate and SOD and CAT activities can be highly recommended for the eco-toxicological assessment. In addition, chlorophyll a also could be used as a targeted parameter for assessing the eco-toxicity of Chlorpyrifos on both Chlorella pyrenoidosa and Merismopedia sp. PMID:27314761

  3. Simultaneous Measurement of Oscillations in Oxygen Evolution and Chlorophyll a Fluorescence in Leaf Pieces 1

    PubMed Central

    Walker, David A.; Sivak, Mirta N.; Prinsley, Roslyn T.; Cheesbrough, John K.

    1983-01-01

    In spinach (Spinacia oleracea) and barley (Hordeum vulgare) leaves, chlorophyll a fluorescence and O2 evolution have been measured simultaneously following re-illumination after a dark interval or when steady state photosynthesis has been perturbed by changes in the gas phase. In high CO2 concentrations, both O2 and fluorescence can display marked dampening oscillations that are antiparallel but slightly out of phase (a rise or fall in fluorescence anticipating a corresponding fall or rise in O2 by about 10 to 15 seconds). Infrared gas analysis measurements showed that CO2 uptake behaved like O2 evolution both in the period of oscillation (about 1 minute) and in its relation to fluorescence. In the steady state, oscillations were initiated by increases in CO2 or by increases or decreases in O2. Oscillations in O2 or CO2 did not occur without associated oscillations in fluorescence and the latter were a sensitive indicator of the former. The relationship between such oscillations in photosynthetic carbon assimilation and chlorophyl a fluorescence is discussed in the context of the effect of ATP or NADPH consumption on known quenching mechanisms. PMID:16663255

  4. Sensitive Detection of Phosphorus Deficiency in Plants Using Chlorophyll a Fluorescence.

    PubMed

    Frydenvang, Jens; van Maarschalkerweerd, Marie; Carstensen, Andreas; Mundus, Simon; Schmidt, Sidsel Birkelund; Pedas, Pai Rosager; Laursen, Kristian Holst; Schjoerring, Jan K; Husted, Søren

    2015-09-01

    Phosphorus (P) is a finite natural resource and an essential plant macronutrient with major impact on crop productivity and global food security. Here, we demonstrate that time-resolved chlorophyll a fluorescence is a unique tool to monitor bioactive P in plants and can be used to detect latent P deficiency. When plants suffer from P deficiency, the shape of the time-dependent fluorescence transients is altered distinctively, as the so-called I step gradually straightens and eventually disappears. This effect is shown to be fully reversible, as P resupply leads to a rapid restoration of the I step. The fading I step suggests that the electron transport at photosystem I (PSI) is affected in P-deficient plants. This is corroborated by the observation that differences at the I step in chlorophyll a fluorescence transients from healthy and P-deficient plants can be completely eliminated through prior reduction of PSI by far-red illumination. Moreover, it is observed that the barley (Hordeum vulgare) mutant Viridis-zb(63), which is devoid of PSI activity, similarly does not display the I step. Among the essential plant nutrients, the effect of P deficiency is shown to be specific and sufficiently sensitive to enable rapid in situ determination of latent P deficiency across different plant species, thereby providing a unique tool for timely remediation of P deficiency in agriculture. PMID:26162430

  5. Simultaneous measurement of oscillations in oxygen evolution and chlorophyll a fluorescence in leaf pieces.

    PubMed

    Walker, D A; Sivak, M N; Prinsley, R T; Cheesbrough, J K

    1983-11-01

    In spinach (Spinacia oleracea) and barley (Hordeum vulgare) leaves, chlorophyll a fluorescence and O(2) evolution have been measured simultaneously following re-illumination after a dark interval or when steady state photosynthesis has been perturbed by changes in the gas phase. In high CO(2) concentrations, both O(2) and fluorescence can display marked dampening oscillations that are antiparallel but slightly out of phase (a rise or fall in fluorescence anticipating a corresponding fall or rise in O(2) by about 10 to 15 seconds). Infrared gas analysis measurements showed that CO(2) uptake behaved like O(2) evolution both in the period of oscillation (about 1 minute) and in its relation to fluorescence. In the steady state, oscillations were initiated by increases in CO(2) or by increases or decreases in O(2). Oscillations in O(2) or CO(2) did not occur without associated oscillations in fluorescence and the latter were a sensitive indicator of the former. The relationship between such oscillations in photosynthetic carbon assimilation and chlorophyl a fluorescence is discussed in the context of the effect of ATP or NADPH consumption on known quenching mechanisms. PMID:16663255

  6. Differential heat sensitivity index in barley cultivars (Hordeum vulgare L.) monitored by chlorophyll a fluorescence OKJIP.

    PubMed

    Oukarroum, Abdallah; El Madidi, Saïd; Strasser, Reto J

    2016-08-01

    The objective of this study was to differentiate the heat tolerance in ten varieties of barley (Hordeum vulgare L.) originating from Morocco. Five modern varieties and five landraces (local varieties) collected at five different geographical localities in the south of Morocco were investigated in the present study. After two weeks of growth, detached leaves were short term exposure to various temperatures (25, 30, 35, 40, and 45 °C) for 10 min in the dark. Two chlorophyll a fluorescence parameters derived from chlorophyll a fluorescence transient (OKJIP) (performance index (PIABS) and relative variable fluorescence at the K-step (VK)) were analysed. Heat treatment had a significant effect on the PIABS and VK at 45 °C treatment and the analysis of variance for PIABS and VK is highly significant between all varieties. The slope of the relationship between logPIABS and VK named heat sensitivity index (HSI) was used to evaluate the thermotolerance of photosystem II (PSII) between the studied barley varieties. According to this approach, barley varieties were screened and ranked for improving heat tolerance. HSI was found to be a new indicator with regard to distinguishing heat tolerance of different barley cultivars. PMID:27093113

  7. Defining "Development".

    PubMed

    Pradeu, Thomas; Laplane, Lucie; Prévot, Karine; Hoquet, Thierry; Reynaud, Valentine; Fusco, Giuseppe; Minelli, Alessandro; Orgogozo, Virginie; Vervoort, Michel

    2016-01-01

    Is it possible, and in the first place is it even desirable, to define what "development" means and to determine the scope of the field called "developmental biology"? Though these questions appeared crucial for the founders of "developmental biology" in the 1950s, there seems to be no consensus today about the need to address them. Here, in a combined biological, philosophical, and historical approach, we ask whether it is possible and useful to define biological development, and, if such a definition is indeed possible and useful, which definition(s) can be considered as the most satisfactory. PMID:26969977

  8. Defining Infertility

    MedlinePlus

    ... of the American Society for Reproductive Medicine Defining infertility What is infertility? Infertility is “the inability to conceive after 12 months ... to conceive after 6 months is generally considered infertility. How common is it? Infertility affects 10%-15% ...

  9. Defining Risk.

    ERIC Educational Resources Information Center

    Tholkes, Ben F.

    1998-01-01

    Defines camping risks and lists types and examples: (1) objective risk beyond control; (2) calculated risk based on personal choice; (3) perceived risk; and (4) reckless risk. Describes campers to watch ("immortals" and abdicators), and several "treatments" of risk: avoidance, safety procedures and well-trained staff, adequate insurance, and a…

  10. Environmental factors associated with long-term changes in chlorophyll-a concentration in the Amazon floodplain

    NASA Astrophysics Data System (ADS)

    Alcântara, E.; Novo, E. M.; Barbosa, C. F.; Bonnet, M.-P.; Stech, J.; Ometto, J. P.

    2011-04-01

    Long-term environmental time series of continuously collected data are fundamental to identify and classify pulses and determine their role in aquatic systems. This paper presents in situ daily mean chlorophyll-a concentration time series, key information for the current understanding of carbon fluxes in and out of the Amazonian floodplain system. This paper also investigates how seasonal fluctuations in water level affect the relationship between chlorophyll-a concentration and some of its controlling limnological (water level, water surface temperature, pH and turbidity) and meteorological (wind intensity, relative humidity and short wave radiation) variables provided by an automatic monitoring system (Integrated System for Environmental Monitoring-SIMA) deployed at Curai Lake. The data are collected in preprogrammed time interval (1 h) and are transmitted by satellite in quasi-real time for any user in a range of 2500 km from the acquisition point. We used Pearson correlation to determine the quantitative relationship between chlorophyll-a time series and others environmental parameters. Fourier power spectrum analyses were applied to identify periods of high variability in chlorophyll-a time series and wavelet power spectrum analyses helped to characterize their time-frequency structure. To further investigate the relationship between chlorophyll-a and the statistically significant variable highlighted by Pearson's correlation, the set of time series was submitted to cross wavelet analysis. The time series of chlorophyll-a shows two high peaks (47 μg L-1 and 53.30 μg L-1) of concentration during a year: first during the rising water and second during the low water level. A small peak was observed during the high water level (10 μg L-1). For the most part of rising, high and receding water level, the chlorophyll-a concentration is often low (from 2.20 μg L-1 to 9.10 μg L-1). chlorophyll-a concentration displays periodicities ranging from 2-60 days, with a

  11. Can upper ocean vertical mixing be determined from ocean surface chlorophyll-a concentrations using data-assimilation?

    NASA Astrophysics Data System (ADS)

    Hahn-Woernle, Lisa; Dijkstra, Henk A.; van der Woerd, Hans J.

    2015-04-01

    While an essential upper-ocean process like the vertical mixing still needs to be determined by complicated in-situ measurements, a wide range of physical and biological surface data of the ocean are provided by remote sensing. Remotely sensed surface chlorophyll-a concentration show for example a strong variation in the seasonal and the latitudinal distribution of phytoplankton growth. Such differences in the growth behaviour are known to be strongly affected by the vertical mixing in the upper ocean. This motivated us to assimilate ocean surface chlorophyll-a concentrations in a turbulence-phytoplankton model to estimate properties of vertical mixing. The Global Ocean Turbulence Model (GOTM) is thereto coupled to an one-dimensional biological model. The parameters of the biological model are calibrated to different locations in the North Atlantic. First we show that the modelled surface chlorophyll-a concentration are sensitive to the vertical mixing coefficient; this sensitivity is a key factor for successful data assimilation. Next, with fixed biological model parameters, we assimilate surface chlorophyll-a concentrations into the model to estimate parameters in the turbulence model using a particle filtering technique. The presentation will focus on the issue how accurately the profile of the vertical mixing coefficient can be determined by assimilating ocean surface chlorophyll-a data into the turbulence-phytoplankton model.

  12. Defining cure.

    PubMed

    Hilton, Paul; Robinson, Dudley

    2011-06-01

    This paper is a summary of the presentations made as Proposal 2-"Defining cure" to the 2nd Annual meeting of the ICI-Research Society, in Bristol, 16th June 2010. It reviews definitions of 'cure' and 'outcome', and considers the impact that varying definition may have on prevalence studies and cure rates. The difference between subjective and objective outcomes is considered, and the significance that these different outcomes may have for different stakeholders (e.g. clinicians, patients, carers, industry etc.) is discussed. The development of patient reported outcome measures and patient defined goals is reviewed, and consideration given to the use of composite end-points. A series of proposals are made by authors and discussants as to how currently validated outcomes should be applied, and where our future research activity in this area might be directed. PMID:21661023

  13. Chlorophyll a Fluorescence in Evaluation of the Effect of Heavy Metal Soil Contamination on Perennial Grasses

    PubMed Central

    Żurek, Grzegorz; Rybka, Krystyna; Pogrzeba, Marta; Krzyżak, Jacek; Prokopiuk, Kamil

    2014-01-01

    Chlorophyll a fluorescence gives information about the plant physiological status due to its coupling to the photosynthetic electron transfer chain and to the further biochemical processes. Environmental stresses, which acts synergistically, disturbs the photosynthesis. The OJIP test, elaborated by Strasser and co-workers, enables comparison of the physiological status of plants grown on polluted vs. control areas. The paper shows that the Chl a measurements are very useful tool in evaluating of heavy metal ions influence on perennial grasses, tested as potential phytoremediators. Among 5 cultivars tested, the highest concentration of Cd and Zn ions, not associated with the yield reduction, was detected in the biomass of tall fescue cv. Rahela. Chl a fluorescence interpreted as double normalized curves pointed out Rahela as the outstanding cultivar under the HM ions stress. PMID:24633293

  14. Tracing the evolution of the light-harvesting antennae in chlorophyll a/b-containing organisms.

    PubMed

    Koziol, Adam G; Borza, Tudor; Ishida, Ken-Ichiro; Keeling, Patrick; Lee, Robert W; Durnford, Dion G

    2007-04-01

    The light-harvesting complexes (LHCs) of land plants and green algae have essential roles in light capture and photoprotection. Though the functional diversity of the individual LHC proteins are well described in many land plants, the extent of this family in the majority of green algal groups is unknown. To examine the evolution of the chlorophyll a/b antennae system and to infer its ancestral state, we initiated several expressed sequence tag projects from a taxonomically broad range of chlorophyll a/b-containing protists. This included representatives from the Ulvophyceae (Acetabularia acetabulum), the Mesostigmatophyceae (Mesostigma viride), and the Prasinophyceae (Micromonas sp.), as well as one representative from each of the Euglenozoa (Euglena gracilis) and Chlorarachniophyta (Bigelowiella natans), whose plastids evolved secondarily from a green alga. It is clear that the core antenna system was well developed prior to green algal diversification and likely consisted of the CP29 (Lhcb4) and CP26 (Lhcb5) proteins associated with photosystem II plus a photosystem I antenna composed of proteins encoded by at least Lhca3 and two green algal-specific proteins encoded by the Lhca2 and 9 genes. In organisms containing secondary plastids, we found no evidence for orthologs to the plant/algal antennae with the exception of CP29. We also identified PsbS homologs in the Ulvophyceae and the Prasinophyceae, indicating that this distinctive protein appeared prior to green algal diversification. This analysis provides a snapshot of the antenna systems in diverse green algae, and allows us to infer the changing complexity of the antenna system during green algal evolution. PMID:17307901

  15. Cross-shelf variation in carbon-to-chlorophyll a ratios in the East China Sea, summer 1998

    NASA Astrophysics Data System (ADS)

    Chang, Jeng; Shiah, Fuh-Kwo; Gong, Gwo-Ching; Chiang, Kuo Ping

    2003-03-01

    Spatial variations of the phytoplankton carbon-to-chlorophyll a ratio (C:chl a) in the East China Sea were investigated during a June 1998 cruise. Based on a regression analysis between particulate organic carbon and chlorophyll a concentrations measured at 2-m depths, estimated values of C:chl a were 13.0 and 92.8 g g -1 for coastal and offshore waters, respectively. In addition, water samples were collected from 5-m depths at three stations with different hydrographic characteristics, and phytoplankton carbon biomass was estimated from microscope-measured cell volumes. At the coastal zone station, chlorophyll a concentration reached 7.9 mg m -3 with Skeletonema costatum as the dominant species. The total phytoplankton carbon was 142.8 mg m -3, and the estimated C:chl a was 18.0 g g -1. At the midshelf station, Synechococcus spp. and Pseudosolenia calcar-avis were the major contributors to phytoplankton carbon. The chlorophyll a concentration was 1.3 mg m -3, and C:chl a was 67.4 g g -1. In contrast, chlorophyll a concentration decreased to 0.1 mg m -3 at the Kuroshio station, where the filamentous cyanobacteria Trichodesmium spp., contributed to most of the phytoplankton carbon, and C:chl a was estimated to be 94.4 g g -1. The C:chl a ratios estimated by the two methods were in close agreement, and a linear relationship was established between the logarithm of chlorophyll a concentration and phytoplankton carbon. The estimated carbon biomass was used to calculate intrinsic growth rates of phytoplankton in the East China Sea. The results indicate that phytoplankton grow actively in the coastal zone, with growth rates often higher than 1.4 day -1, but much lower rates were observed near the margin of the continental shelf.

  16. [Temporal and Spatial Variation of Nutrients and Chlorophyll a, and Their Relationship in Pengxi River Backwater Area, Three Gorges Reservoir].

    PubMed

    Zhang, Lei; Wei, Jian-jun; Fu, Li; Zhou, Chuan; Haffner, Douglas G

    2015-06-01

    In order to explore the temporal and spatial variation of nutrients and chlorophyll a and their relationship in the Three Gorges Reservoir, nutrients and chlorophyll a were monitored chronically and frequently in Gaoyang Lake in Pengxi River in the Three Gorges Reservoir from May 2013 to May 2014. The study showed that the thermal stratification affected the vertical distribution of chlorophyll a and nutrients. The water thermal stratification in Gaoyang Lake occurred in early March and disappeared in the middle of September, and there was no stratification in winter ( November to February of the second year). Chlorophyll a in the surface water increased from 14.92 microg x L(-1) to 183.73 microg x L(-1) and then the chlorophyll a concentration decreased with the increasing depth of the mixing layer ( epilimnion) in the spring of 2014. Furthermore, phosphorus concentration was significantly different among layers when the water stratified and the concentration gradient of TP between the surface and the bottom was (0.18 +/- 0.04) mg x L(-1). When water was not stratified in Gaoyang Lake, the surface, middle and bottom layers had similar concentrations of chlorophyll a and nutrients, respectively. Nitrate N and dissolved phosphorus were the major components of TN and TP, respectively, during the high water level period in Gaoyang Lake with nitrate N accounting for 71.4%-95.4% of TN and dissolved phosphorus 42.7%-94.% of TP, showing that the backwater from the mainstream of Yangtze was the main source of nitrate N and dissolved phosphorus in Gaoyang Lake. PMID:26387308

  17. Molecular topology of the photosynthetic light-harvesting pigment complex, peridinin-chlorophyll a-protein, from marine dinoflagellates.

    PubMed

    Song, P S; Koka, P; Prézelin, B B; Haxo, F T

    1976-10-01

    The photosynthetic light-harvesting complex, peridinin-chlorophyll a-protein, was isolated from several marine dinoflagellates including Glenodinium sp. by Sephadex and ion-exchange chromatography. The carotenoid (peridinin)-chlorophyll a ratio in the complex is estimated to be 4:1. The fluorescence excitation spectrum of the complex indicates that energy absorbed by the carotenoid is transferred to the chlorophyll a molecule with 100% efficiency. Fluorescence lifetime measurements indicate that the energy transfer is much faster than fluorescence emission from chlorophyll a. The four peridinin molecules within the complex appear to form two allowed exciton bands which split the main absorption band of the carotenoid into two circular dichronic bands (with negative ellipticity band at 538 nm and positive band at 463 nm in the case of peridinin-chlorophyl a-protein complex from Glenodinium sp.). The fluorescence polarization of chlorophyll a in the complex at 200 K is about 0.1 in both circular dichroic excitation bands of the carotenoid chromophore. From these circular dichroic and fluorescence polarization data, a possible molecular arrangement of the four peridinin and chlorophyll molecules has been deduced for the complex. The structure of the complex deduced is also consistent with the magnitude of the exciton spliting (ca. greater than 3000 cm-1) at the intermolecular distance in the dimer pair of peridinin (ca. 12 A). This structural feature accounts for the efficient light-harvesting process of dinoflagellates as the exciton interaction lengthens the lifetime of peridinin (radiative) and the complex topology increases the energy transfer probability. The complex is, therefore, a useful molecular model for elucidating the mechanism and efficiency of solar energy conversion in vivo as well as in vitro. PMID:987799

  18. Synthesis of chlorophyll-a derivatives methylated in the 3-vinyl group and their intrinsic site energy.

    PubMed

    Tamiaki, Hitoshi; Tsuji, Kazuki; Kuno, Masaki; Kimura, Yuki; Watanabe, Hiroaki; Miyatake, Tomohiro

    2016-07-01

    Wittig reaction of methyl pyropheophorbide-d possessing the 3-formyl group gave readily methyl pyropheophorbides-a bearing a variety of 3-alkenyl groups as semi-synthetic models of chlorophyll-a. The 3-substituents rotated around the C3-C3(1) bond from the coplanar conformation with the chlorin π-system, moving the redmost visible absorption maxima to a shorter wavelength. The model experiments showed that natural chlorophyll-a carrying the 3-vinyl group would take a similar rotamer to control its intrinsic site energy. PMID:27210434

  19. Defining chaos

    SciTech Connect

    Hunt, Brian R.; Ott, Edward

    2015-09-15

    In this paper, we propose, discuss, and illustrate a computationally feasible definition of chaos which can be applied very generally to situations that are commonly encountered, including attractors, repellers, and non-periodically forced systems. This definition is based on an entropy-like quantity, which we call “expansion entropy,” and we define chaos as occurring when this quantity is positive. We relate and compare expansion entropy to the well-known concept of topological entropy to which it is equivalent under appropriate conditions. We also present example illustrations, discuss computational implementations, and point out issues arising from attempts at giving definitions of chaos that are not entropy-based.

  20. The photosynthetic response to a shift in the chlorophyll a to chlorophyll B ratio of chlorella.

    PubMed

    Reger, B J; Krauss, R W

    1970-10-01

    The chlorophyll a:b ratio was shifted in Chlorella vannielii by varying the illuminance under which the cells were cultured-the ratio increased from 2.9, 3.0, 4.0, and 4.8 to 6.2, respectively, at 100, 300, 900, 2,700 and 6,000 foot candles. The 6,000-foot candle cells retained an optimal growth rate at the chlorophyll a:b ratio of 6.2 which was the upper limit of normal growth. Comparisons were made between the 300-and 6,000-foot candle cultures to determine the significance to the photosynthetic mechanism of a shift in the chlorophyll a:b ratio.The high light cells (6,000 foot candles) contained only one-tenth the total amount of chlorophyll of the low light cells (300 foot candles) based on dry weight. The total chlorophyll per cell of the high light cells was one-fifth of that in the low light cells. Electron micrographs indicated differences in chloroplast structure. An average of five or six thylakoids composed a granum-like region of the low light chloroplasts, whereas only a pair of thylakoids at most was found in the high light chloroplasts. The high light chloroplasts had more starch. On a dry weight basis, the high light cells had a respiration rate 3 times that of the low light cells. Based on chlorophyll, the respiration rate of the high light cells was 26 times greater. Based on dry weight, the oxygen evolution for both cultures was essentially the same at 6,000 foot candles; however, at 300 foot candles the rate for the low light cells was about 5 times faster than that of the high light cells. With chlorophyll as the index, the rates of the high light cells were higher than those of the low light cells-7 times faster at 6,000 and 2 times faster at 300 foot candles. At 10,000 foot candles, the low light-grown cells underwent photooxidation, whereas the high light grown cells photosynthesized at a rate slightly higher than at 6,000 foot candles.Action spectra of system II (oxygen evolution) from a modulated polarograph indicated photochemical

  1. Reconstitution of chlorophyll a/b light-harvesting complexes: xanthophyll-dependent assembly and energy transfer

    SciTech Connect

    Plumley, F.G.; Schmidt, G.W.

    1987-01-01

    A method for in vitro reconstitution of the chlorophyll a/b light-harvesting complex from LiDodSO/sub 4//heat-denatured or acetone-extracted photosynthetic membranes has been developed. Characterization of the minimum components necessary for the functional organization or pigments in these membrane complexes reveals that xanthophylls are essential structural components.

  2. Relationships Between Concentrations of Phytoplankton Chlorophyll a and Total Nitrogen in Estuaries: Implications for Development of Nutrient Criteria

    EPA Science Inventory

    Regression relationships between summer surface concentrations of phytoplankton chlorophyll a and total (inorganic + organic) nitrogen have been developed for four estuarine embayments and six riverine estuaries on the U.S. Atlantic and Gulf of Mexico coasts. All systems show spa...

  3. Method 445.0 In Vitro Determination of Chlorophyll a and Pheophytin ain Marine and Freshwater Algae by Fluorescence

    EPA Science Inventory

    This method provides a procedure for low level determination of chlorophyll a (chl a) and its magnesium free derivative, pheophytin a (pheo a), in marine and freshwater phytoplankton using fluorescence detection.(1,2) Phaeophorbides present in the sample are determined collective...

  4. Allelic variations of a light harvesting chlorophyll A/B protein gene (Lhcb1) associated with agronomic traits in Barley

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Light-harvesting chlorophyll a/b-binding protein (LHCP) is one of the most abundant chloroplast proteins in plants. Its main function is to collect and transfer light energy to photosynthetic reaction centers. However, the roles of different LHCPs in light-harvesting antenna systems remain obscure. ...

  5. Satellite Remote Sensing of Chlorophyll a in Support of Nutrient Management in the Neuse and Tar-Pamlico River Estuaries

    EPA Science Inventory

    The North Carolina Environmental Management Commission (EMC) has adopted as a water quality standard that chlorophyll a concentration should not exceed 40 ug/L in sounds, estuaries and other slow-moving waters. Exceedances require regulators to develop a Total Maximum Daily Limit...

  6. RELATIONSHIPS BETWEEN SUMMER CONCENTRATIONS OF TOTAL NITROGEN AND CHLOROPHYLL A IN TEN COASTAL SYSTEMS IN THE EASTERN UNITED STATES

    EPA Science Inventory

    We have examined relationships between summer (JuneAugust) average concentrations of total nitrogen (TN) and chlorophyll a (chl a) concentrations in the near-shore Mid-Atlantic Bight and nine bays and estuaries in the eastern United States: Boston Harbor/Massachusetts Bay, Long I...

  7. An Improved Method for the Extraction and Thin-Layer Chromatography of Chlorophyll A and B from Spinach

    ERIC Educational Resources Information Center

    Quach, Hao T.; Steeper, Robert L.; Griffin, William G.

    2004-01-01

    A simple and fast method, which resolves chlorophyll a and b from spinach leaves on analytical plates while minimizing the appearance of chlorophyll degradation products is shown. An improved mobile phase for the Thin-layer chromatographic analysis of spinach extract that allows for the complete resolution of the common plant pigments found in…

  8. Validation of MODIS FLH and In Situ Chlorophyll a from Tampa Bay, Florida (USA)

    NASA Technical Reports Server (NTRS)

    Fischer, Andrew; MorenoMadrinan, Max J.

    2012-01-01

    Satellite observation of phytoplankton concentration or chlorophyll-a (chla) is an important characteristic, critically integral to monitoring coastal water quality. However, the optical properties of estuarine and coastal waters are highly variable and complex and pose a great challenge for accurate analysis. Constituents such as suspended solids and dissolved organic matter and the overlapping and uncorrelated absorptions in the blue region of the spectrum renders the blue-green ratio algorithms for estimating chl-a inaccurate. Measurement of suninduced chlorophyll fluorescence, on the other hand, which utilizes the near infrared portion of the electromagnetic spectrum may, provide a better estimate of phytoplankton concentrations. While modelling and laboratory studies have illustrated both the utility and limitations of satellite algorithms based on the sun induced chlorophyll fluorescence signal, few have examined the empirical validity of these algorithms or compared their accuracy against bluegreen ratio algorithms . In an unprecedented analysis using a long term (2003-2011) in situ monitoring data set from Tampa Bay, Florida (USA), we assess the validity of the FLH product from the Moderate Resolution Imaging Spectrometer against a suite of water quality parameters taken in a variety of conditions throughout this large optically complex estuarine system. . Overall, the results show a 106% increase in the validity of chla concentration estimation using FLH over the standard chla estimate from the blue-green OC3M algorithm. Additionally, a systematic analysis of sampling sites throughout the bay is undertaken to understand how the FLH product responds to varying conditions in the estuary and correlations are conducted to see how the relationships between satellite FLH and in situ chlorophyll-a change with depth, distance from shore, from structures like bridges, and nutrient concentrations and turbidity. Such analysis illustrates that the correlations between

  9. Chlorophyll a Covalently Bonded to Organo-Modified Translucent Silica Xerogels: Optimizing Fluorescence and Maximum Loading.

    PubMed

    García-Sánchez, M A; Serratos, I N; Sosa, R; Tapia-Esquivel, T; González-García, F; Rojas-González, F; Tello-Solís, S R; Palacios-Enriquez, A Y; Esparza Schulz, J M; Arrieta, A

    2016-01-01

    Chlorophyll is a pyrrolic pigment with important optical properties, which is the reason it has been studied for many years. Recently, interest has been rising with respect to this molecule because of its outstanding physicochemical properties, particularly applicable to the design and development of luminescent materials, hybrid sensor systems, and photodynamic therapy devices for the treatment of cancer cells and bacteria. More recently, our research group has been finding evidence for the possibility of preserving these important properties of substrates containing chlorophyll covalently incorporated within solid pore matrices, such as SiO₂, TiO₂ or ZrO₂ synthesized through the sol-gel process. In this work, we study the optical properties of silica xerogels organo-modified on their surface with allyl and phenyl groups and containing different concentrations of chlorophyll bonded to the pore walls, in order to optimize the fluorescence that these macrocyclic species displays in solution. The intention of this investigation was to determine the maximum chlorophyll a concentration at which this molecule can be trapped inside the pores of a given xerogel and to ascertain if this pigment remains trapped as a monomer, a dimer, or aggregate. Allyl and phenyl groups were deposited on the surface of xerogels in view of their important effects on the stability of the molecule, as well as over the fluorescence emission of chlorophyll; however, these organic groups allow the trapping of either chlorophyll a monomers or dimers. The determination of the above parameters allows finding the most adequate systems for subsequent in vitro or in vivo studies. The characterization of the obtained xerogels was performed through spectroscopic absorption, emission and excitation spectra. These hybrid systems can be employed as mimics of natural systems; the entrapment of chlorophyll inside pore matrices indicates that it is possible to exploit some of the most physicochemical

  10. Chlorophyll a and phytoplankton in the Pomeranian Bay during and after the flood event

    NASA Astrophysics Data System (ADS)

    Gromisz, Sławomira; Zalewski, Mariusz; Ochocki, Stanisław; Kownacka, Janina M.

    1998-06-01

    Studies dealing with the impact of the flood event in the Odra River in July 1997 on the phytoplankton in the Pomeranian Bay were based on three cruises: in late July/early August, at the end of August, and in October 1997. During those studies, concentrations of chlorophyll a were measured. During the second cruise, the phytoplankton composition was investigated additionally. In August 1997, in the entire southern part of the Pomeranian Bay within a radius of about 30 km from the Swina mouth, chlorophyll concentrations were 3 4 times higher than in July 1996 and amounted to 5 15 mg/m3. Further offshore, concentrations were about 2 times higher (2 5 mg/m3) as compared to the 1996 values. At the beginning of August and in the first days of the second cruise, chlorophyll a concentrations were highest in the vicinity of the Swina mouth, reaching 15 25 mg/m3. They did not, however, differ much from the maximum values observed in July 1996. On 27 28 August 1997, a strong north-easterly wind caused open Bay waters to be transported towards the Swina outlet, leading to mixing of water masses and transport of phytoplankton with plume water towards the north-west. The chlorophyll concentrations measured on 19 29 October 1997 ranged from 2 9 mg/ m3 in the entire Bay and did not differ from those measured on 20 Sept. 3 Oct. 1993. A significant impact of the flood wave on phytoplankton composition in the Pomeranian Bay in August 1997 was not observed. Blue-green algae, blooms of which are typical of summer periods in the Baltic Sea, predominated in the entire area. Four potentially toxic species (Anabaena spiroides, Aphanizomenon flosaquae, Microcystis aeruginosa and Nodularia spumigena) appeared but did not occur in “bloom” quantities. The abundance of the dinoflagellate Prorocentrum minimum, which also is a potentially toxic species, was relatively high in the north-western part of the region studied, but this area is beyond the direct impact of estuarine waters. The

  11. [Algorithm for estimating chlorophyll-a concentration in case II water body based on bio-optical model].

    PubMed

    Yang, Wei; Chen, Jin; Mausushita, Bunki

    2009-01-01

    In the present study, a novel retrieval method for estimating chlorophyll-a concentration in case II waters based on bio-optical model was proposed and was tested with the data measured in the laboratory. A series of reflectance spectra, with which the concentration of each sample constituent (for example chlorophyll-a, NPSS etc.) was obtained from accurate experiments, were used to calculate the absorption and backscattering coefficients of the constituents of the case II waters. Then non-negative least square method was applied to calculate the concentration of chlorophyll-a and non-phytoplankton suspended sediments (NPSS). Green algae was firstly collected from the Kasumigaura lake in Japan and then cultured in the laboratory. The reflectance spectra of waters with different amounts of phytoplankton and NPSS were measured in the dark room using FieldSpec Pro VNIR (Analytical Spectral Devises Inc. , Boulder, CO, USA). In order to validate whether this method can be applied in multispectral data (for example Landsat TM), the spectra measured in the laboratory were resampled with Landsat TM bands 1, 2, 3 and 4. Different combinations of TM bands were compared to derive the most appropriate wavelength for detecting chlorophyll-a in case II water for green algae. The results indicated that the combination of TM bands 2, 3 and 4 achieved much better accuracy than other combinations, and the estimated concentration of chlorophyll-a was significantly more accurate than empirical methods. It is expected that this method can be directly applied to the real remotely sensed image because it is based on bio-optical model. PMID:19385201

  12. Study of the Conformational Changes of Chlorophyll a (Chl a) Colloids with the Atomic Force Microscope.

    PubMed

    Boussaad; Tazi; Leblanc

    1999-01-15

    Atomic force microscopic (AFM) images of chlorophyll a (Chl a) colloids deposited onto mica and Au(111) present two different shapes. The colloids appear as clouds on mica and as large chains on Au(111). This difference in topography is attributed to different interactions between the colloids and the substrate. The real-time changes occurring during the electrodeposition of the colloids are also monitored. For an applied electric field intensity varying between 5 x 10(3) and 25 x 10(4) V/m, the colloids are opened and flattened relative to a deposition in the absence of an electric field and the drop method. However, when these films are exposed to ethanol vapors, disaggregation occurrs. These changes indicate that the association of Chl a dimers can form nanocrystals with large size distribution: 45-100 nm. Arrangement of nanocrystals in colloids is a characteristic feature of microcrystalline Chl a. The interaction between the colloids and H2O can also provoke aggregate dissociation. Copyright 1999 Academic Press. PMID:9885260

  13. A bio-optical approach to estimating chlorophyll-a concentration from hyperspectral remote sensing

    NASA Astrophysics Data System (ADS)

    Li, Linhai; Li, Lin; Song, Kaishan

    2010-08-01

    Eagle Creek Reservoir is one of three central Indiana reservoirs supplying drinking water for the residents of Indianapolis. The occurrence of blue-green algae blooms resulting from high nutrient input has been a major public concern so that estimation of chlorophyll-a concentration of this reservoir is significantly important for assessing the reservoir's water quality. Empirical and semi-empirical methods were used in our previous studies for estimating CHL. Due to limitations to empirical and semi-empirical methods, a bio-optical model is tested in this study. Field campaigns were carried out in Eagle Creek Reservoir in central Indiana, and water samples analyzed for water quality parameter concentrations and their inherent optical properties (IOPs). A bio-optical model parameterized with these derived IOPs is used to estimate CHL concentration through a matrix inversion of hyperspectral data, and its performance is compared with those for empirical and semi-empirical models. The result demonstrates that the bio-optical model results in a higher correlation than empirical and semi-empirical models do.

  14. Paths of deactivation of excitation of chlorophyll a in various model systems

    NASA Astrophysics Data System (ADS)

    Frackowiak, Danuta; Zelent, Bogumil; Malak, Henryk M.; Cegielski, Roman; Planner, Alfons; Goc, Jacek; Niedbalska, Malgorzata

    1994-08-01

    Chlorophyll a (Chl) in most model systems (monolayers, fluid solvents, adsorbed layers, and polymer films) occurs in three forms: `dry monomers' (isolated from interaction with water), hydrated dimers and oligomers built from such dimers; but in nematic liquid crystal (LC) cell `dry monomers' are predominant. It is a competition between the various paths of deactivation of excited Chl. Excitation energy can be emitted as fluorescence, or delayed luminescence, transferred to other forms of Chl (ET), thermally deactivated or used for photochemical reactions. In order to compare the efficiency of these various paths the following measurements were done and analyzed: absorption, fluorescence, fluorescence excitation, photoacoustic spectra, and lifetime of fluorescence in ps range. There are some important differences between Chl in LC cell and polymer films: Chl in LC cell has a much lower concentration of aggregated forms and the pigment molecules are more uniformly distributed as compared to the Chl in polymer samples. To explain ET in polymer films the fractals model has to be used, whereas mean distances between solvated Chl molecules in LC can be obtained from dye concentration. In order to establish the interaction between Chl a and (beta) -carotene the LC cell with both pigments were also investigated.

  15. Spectral characteristics and colloidal properties of chlorophyll a{prime} in aqueous methanol

    SciTech Connect

    Oba, Toru; Mimuro, Mamoru; Wang, Z.Y.; Nozawa, Tsunenori; Yoshida, Shoichiro; Watanabe, Tadashi

    1997-04-17

    The `phase behavior` of chlorophyll a` (Chl a`, C13{sup 2}-epimer of Chl a) dissolved in aqueous methanol was examined in terms of the composition of the solvent. The study aimed at elucidating the property of Chl a`, the exotic pigment found in a photosynthetic reaction center complex, as well as at clarifying the nature of the Chl aggregation in aqueous media. Visible absorption, circular dichroism (CD), fluorescence and resonance Raman spectroscopies, dynamic light-scattering measurements, and electron microscopy were utilized. Chl a` formed either of two types of colloids depending on the solvent composition. The one formed over a wide methanol volume percentage (ca. 73-30%) commonly possessed a single microscopic structural unit that yielded the double-peaked absorption (ca. 690 and 715 nm) accompanied by a symmetric dispersed-type CD spectrum. Increasing methanol concentration within this solvent composition range enhanced the size of the colloid and finally caused critical opalescence, which was reminiscent of the critical behavior of the aqueous solution of nonionic surfactants. These findings indicate that the microscopic structure of the Chl a` aggregate was independent of the size and shape of the colloid. The difference between the aggregation behaviors of Chl a and a` suggests a narrower choice of possible molecular arrangements in the Chl a` aggregate as an inherent property of the pigment. 37 refs., 11 figs.

  16. Singlet and triplet energy transfer in the peridinin-chlorophyll a-protein from Amphidinium carterae

    SciTech Connect

    Bautista, J.A.; Frank, H.A.; Hiller, R.G.; Sharples, F.P.; Gosztola, D.; Wasielewski, M. |

    1999-04-08

    The spectroscopic properties of peridinin in solution, and the efficiency and dynamics of energy transfer from peridinin to chlorophyll a in the peridinin-chlorophyll-protein (PCP) from Amphidinium carterae, were studied by steady-state absorption, fluorescence, fluorescence excitation, and fast transient optical spectroscopy. Steady-state measurements of singlet energy transfer from peridinin to chlorophyll revealed an 88 {+-} 2% efficiency. Fast-transient absorption experiments showed that the excited S{sub 1} state of peridinin decayed in 13.4 {+-} 0.6 ps in methanol and 3.1 {+-} 0.4 ps in the PCP complex after direct excitation of the carotenoid. The onset of the bleaching of the chlorophyll absorption band at 672 nm, signifying the arrival of the excitation from the carotenoid, occurred in 3.2 {+-} 0.3 ps. These data show that the primary route of energy transfer from peridinin to chlorophyll in the PCP complex is through the S{sub 1} state of peridinin. Nanosecond time-resolved transient optical spectroscopy revealed that chlorophyll triplet states are efficiently quenched by peridinin whose triplet state subsequently decays with a lifetime of 10 {+-} 1 {micro}s in the PCP complex. Close association between the peridinins and chlorophyll, which is clearly evident in the 3-D structure of the PCP complex, along with proper alignment of pigments and energy state matching are responsible for the high efficiencies of the photochemical processes.

  17. Chlorophyll-a and nutrient distribution of Pahang coastal waters during southwest monsoon using satellite images

    NASA Astrophysics Data System (ADS)

    Shaari, F.; Mustapha, M. A.; Ali, M. M.; Lihan, T.

    2013-11-01

    The relationship of nutrients and phytoplankton chlorophyll-a (Chl-a) is a basis for understanding eutrophication in a coastal marine ecosystem. This study was conducted to determined Chl-a and nutrient distribution during the southwest monsoon in the coastal water of Pahang, Malaysia. Data of Chl-a from Level 1A data (1 km spatial resolution) were processed to monthly composites Level 3 of Aqua MODIS data from January 2006 to December 2011 to get climatological images. Distribution of Chl-a was described by the spatial map using satellite image of the ocean color properties. While nutrient distribution were explained using kriging technique and mapped using ArcGIS. Chl-a was higher near coastal area and lower towards off shore area due to the terrestrial influence especially from river discharge and aquaculture activity. High value of nitrate, ammonia and phosphate in Pahang coastal area during the southwest monsoon indicates influence of terrestrial discharge especially from river outflow and aquaculture. Distribution of Chl-a along the Pahang coastal area was influenced by nutrient.

  18. Excitonic dynamics of Chlorophyll-a molecules in chitosan hydrogel scaffold.

    PubMed

    Mandal, Pubali; Manna, Jhimli Sarkar; Das, Debmallya; Mitra, Manoj Kumar

    2015-04-01

    Biomimetic photo harvesting architecture has been proposed as an alternative for existing solar conversion systems. This fact led us to the successful realization of non-coherent electron hopping [hopping rate 4.28 ns(-1)] through excitonically coupled Chlorophyll-a (Chl-a) molecules within chitosan hydrogel matrix via TCSPC (Time Correlated Single Photon Count) and fluorescence anisotropy measurements. Chl-a molecules remain stable within the hydrogel matrix up to 3 months, as evidenced from UV-vis spectroscopy. The mono-exponential decay parameter with 78 picoseconds time scale, high initial anisotropy data [r0 = 0.33] and with reduced TCSPC lifetime [1.311 ns] of 23° in plane aligned Chl-a macrocycles, indicate that hopping excitonic cascade is prominent among chlorophyll molecules. From the Raman Spectra, it can be postulated that they form a highly co-ordinated closely packed structure via water molecules within chitosan hydrogel due to 6th co-ordination through central Mg of porphyrin macrocycle. All these data predict that this chlorophyll-chitosan hydrogel can be an active component in artificial light harvesting systems. PMID:25635616

  19. Assessment of remotely sensed chlorophyll-a concentration in Guanabara Bay, Brazil

    NASA Astrophysics Data System (ADS)

    Oliveira, Eduardo N.; Fernandes, Alexandre M.; Kampel, Milton; Cordeiro, Renato C.; Brandini, Nilva; Vinzon, Susana B.; Grassi, Renata M.; Pinto, Fernando N.; Fillipo, Alessandro M.; Paranhos, Rodolfo

    2016-04-01

    The Guanabara Bay (GB) is an estuarine system in the metropolitan region of Rio de Janeiro (Brazil), with a surface area of ˜346 km2 threatened by anthropogenic pressure. Remote sensing can provide frequent data for studies and monitoring of water quality parameters, such as chlorophyll-a concentration (Chl-a). Different combination of Medium Resolution Imaging Spectrometer (MERIS) remote sensing reflectance band ratios were used to estimate Chl-a. Standard algorithms such as Ocean Color 3-band, Ocean Color-4 band, fluorescence line height, and maximum chlorophyll index were also tested. The MERIS Chl-a estimates were statistically compared with a dataset of in situ Chl-a (2002 to 2012). Good correlations were obtained with the use of green, red, and near-infrared bands. The best performing algorithm was based on the red (665 nm) and green (560 nm) band ratio, named "RG3" algorithm (r2=0.71, chl-a=62,565*x1.6118). The RG3 was applied to a time series of MERIS images (2003- to 2012). The GB has a high temporal and spatial variability of Chl-a, with highest values found in the wet season (October to March) and in some of the most internal regions of the estuary. Lowest concentrations are found in the central circulation channel due to the flushing of ocean water masses promoted by pumping tide.

  20. Detailed investigation of ROS arisen from chlorophyll a/Chitosan based-biofilm.

    PubMed

    Rizzi, Vito; Fini, Paola; Semeraro, Paola; Cosma, Pinalysa

    2016-06-01

    The aim of this work is to study the nature of reactive oxygen species, ROS, arisen from Chitosan/2-HP-β-Cyclodextrin/Chlorophyll a (CH/CD/Chla) blended biofilm under a photodynamic activity. Suitable molecules, called primary acceptors, able to react selectively with ROS, in turn generated by the photosensitizer (PS), herein Chla, are used to attempt this purpose. The changes of the absorption and the emission spectra of these acceptors after the irradiation of aqueous solution containing the active biofilm have provided the specific nature of ROS and thus the main pathway of reaction followed by PS, in our condition. The (1)O2 formation was unveiled using Uric Acid (UA) and 9,10-diphenilanthracene (DPA). On the other hand, 2,7- dichlorofluorescin and Ferricytochrome c (Cyt-c) were used to detect the formation of hydrogen peroxide and superoxide radical anion, respectively. Results suggest that among the possible pathways of reaction, namely Type I and Type II, potentially followed by PSs, in our condition the hybrid biofilm CH/CD/Chla follows mainly Type II mechanism with the formation of (1)O2. However, the latter is involved in subsequent pathway of reaction involving Chla inducing, in addition, the formation of O2(-) and H2O2. PMID:26966998

  1. Retrieval of chlorophyll a and suspended solid concentrations by hyperspectral remote sensing in Taihu Lake, China

    NASA Astrophysics Data System (ADS)

    Yang, Dingtian; Pan, Delu; Zhang, Xiaoyu; Zhang, Xiaofeng; He, Xianqiang; Li, Shujing

    2006-12-01

    Chlorophyll a (chl- a) and suspended solid concentrations are two frequently used water quality parameters for monitoring a lake. Traditional measurement of chl- a and suspended solids, requiring laborious laboratory work, which is often expensive and time consuming. Hyperspectral remote-sensing measurement provides a fast and easy tool for estimating water trophic status. In situ hyperspectral data on March 7 8, July 6 7, September 20 and December 7 8, 2004 and the corresponding water chemical data were used to regress the algorithm of water quality parameters. Results showed that the peak of water leaving radiance around 700 nm ( R 700) varied proportionally with chl- a concentration, and moved to infrared when algal bloom occurred. The reflectance ratio of R 702/ R 685 was well correlated with chl- a when water surface in no algal bloom case and the correlation coefficient was better if absorption of phycocyanin was considered. The reflectance ratio R 620/ R 531 was highly correlated to the concentration of suspended solids. The relationship between suspended solids and other band groups were also compared. Secchi disk depth could be calculated by non-linear correlation with suspended solids concentration.

  2. Geomagnetic and strong static magnetic field effects on growth and chlorophyll a fluorescence in Lemna minor.

    PubMed

    Jan, Luka; Fefer, Dušan; Košmelj, Katarina; Gaberščik, Alenka; Jerman, Igor

    2015-04-01

    The geomagnetic field (GMF) varies over Earth's surface and changes over time, but it is generally not considered as a factor that could influence plant growth. The effects of reduced and enhanced GMFs and a strong static magnetic field on growth and chlorophyll a (Chl a) fluorescence of Lemna minor plants were investigated under controlled conditions. A standard 7 day test was conducted in extreme geomagnetic environments of 4 µT and 100 µT as well as in a strong static magnetic field environment of 150 mT. Specific growth rates as well as slow and fast Chl a fluorescence kinetics were measured after 7 days incubation. The results, compared to those of controls, showed that the reduced GMF significantly stimulated growth rate of the total frond area in the magnetically treated plants. However, the enhanced GMF pointed towards inhibition of growth rate in exposed plants in comparison to control, but the difference was not statistically significant. This trend was not observed in the case of treatments with strong static magnetic fields. Our measurements suggest that the efficiency of photosystem II is not affected by variations in GMF. In contrast, the strong static magnetic field seems to have the potential to increase initial Chl a fluorescence and energy dissipation in Lemna minor plants. PMID:25708622

  3. Is the trend in chlorophyll-a in the Arabian Sea decreasing?

    NASA Astrophysics Data System (ADS)

    Prakash, Prince; Prakash, Satya; Rahaman, Hasibur; Ravichandran, M.; Nayak, Shailesh

    2012-12-01

    Recent studies of satellite-derived Chlorophyll concentrations (Chl-a) in the western Arabian Sea (AS) have suggested an increasing temporal trend, but the length of the records used have typically been too short to resolve longer-term trends, if any. Our analysis of a long term satellite ocean color data shows a change of trend in the summer chlorophyll for the western AS before and after 2003; Chl-a concentration was indeed increasing till 2003, but appears to be declining since then, indicating a secular multi-year trend in Chl-a variability. However, this trend is not uniform over the entire region. Analysis of wind, sea surface temperature (SST), Sea Level Anomaly (SLA) and thermocline depth, suggests that the declining summer monsoon chlorophyll-a (Chl-a) concentration may be due to increasing SLA in this region. The earlier observed biological changes in the western AS could be an artifact of the change in local winds and ocean dynamics, which may be a part of the natural long-term variability.

  4. Chlorophyll a fluorescence lifetime reveals reversible UV-induced photosynthetic activity in the green algae Tetraselmis.

    PubMed

    Kristoffersen, Arne S; Hamre, Børge; Frette, Øyvind; Erga, Svein R

    2016-04-01

    The fluorescence lifetime is a very useful parameter for investigating biological materials on the molecular level as it is mostly independent of the fluorophore concentration. The green alga Tetraselmis blooms in summer, and therefore its response to UV irradiation is of particular interest. In vivo fluorescence lifetimes of chlorophyll a were measured under both normal and UV-stressed conditions of Tetraselmis. Fluorescence was induced by two-photon excitation using a femtosecond laser and laser scanning microscope. The lifetimes were measured in the time domain by time-correlated single-photon counting. Under normal conditions, the fluorescence lifetime was 262 ps, while after 2 h of exposure to UV radiation the lifetime increased to 389 ps, indicating decreased photochemical quenching, likely caused by a damaged and down-regulated photosynthetic apparatus. This was supported by a similar increase in the lifetime to 425 ps when inhibiting photosynthesis chemically using DCMU. Furthermore, the UV-stressed sample was dark-adapted overnight, resulting in a return of the lifetime to 280 ps, revealing that the damage caused by UV radiation is repairable on a relatively short time scale. This reversal of photosynthetic activity was also confirmed by [Formula: see text] measurements. PMID:26538330

  5. Photodynamic efficiency of a chlorophyll-a derivative in vitro and in vivo.

    PubMed

    Zhang, Xiang-Hua; Zhang, Li-Jun; Sun, Jing-Jian; Yan, Yi-Jia; Zhang, Li-Xin; Chen, Na; Chen, Zhi-Long

    2016-07-01

    This paper reports the antitumor activity of a chlorophyll-a derivative, 2-[1-hydroxyethyl]-2-devinylpyropheophorbide-a (HEPa). Photophysical characteristics of HEPa were measured. And its cytotoxicity, intracellular localization, biodistribution, efficiency of photodynamic therapy (PDT), histological analysis were investigated using human bile duct carcinoma cells (QBC-939) and QBC-939 tumor bearing BABL/c nude mice as animal model. The results showed that HEPa was localized mainly within the cytoplasmic region and partially in lysosome. Biodistribution of HEPa in QBC-939 tumor bearing BABL/c nude mice showed its fast rate of clearance and high tumor selectivity. In vitro, HEPa had low dark toxicity and high photoxicity against QBC-939 cells. The inhibition rate of QBC-939 tumor could increase up to 92.3%, and H&E staining confirmed that HEPa could cause serious damage to the tumor with light dose of 100J/cm(2), implying that HEPa has potential to be a new antitumor candidate for photodynamic therapy (PDT). PMID:27261603

  6. Alterations in chlorophyll a/b binding proteins in Solanaceae cybrids.

    PubMed

    Babiychuk, E; Schantz, R; Cherep, N; Weil, J H; Gleba, Y; Kushnir, S

    1995-12-20

    In this study we have constructed a number of plants (cybrids), in which the nuclear genome of Nicotiana plumbaginifolia is combined with the plastome of Atropa belladonna, or the nuclear genome of N. tabacum with plastomes of Lycium barbarum, Scopolia carniolica, Physochlaine officinalis or Nolana paradoxa. Our biochemical and immunological analyses prove that in these cybrids the biogenesis of the chlorophyll a/b binding proteins (CAB) of the light harvesting complex II (LHCII) is altered. Besides normal sized CAB polypeptides of 27, 25.5 and 25 kDa, which become less abundant, the cybrids analyzed have additional polypeptides of 26, 24.5 and 24 kDa. Direct protein micro-sequencing showed that at least two truncated 26 kDa CAB polypeptides in plant cells containing a nucleus of N. plumbaginifolia and plastids of A. belladonna are encoded by the type 1 Lhcb genes. These polypeptides are 11-12 amino acids shorter at the N-terminus than the expected size. Based on the available data we conclude that the biogenesis of the LHCII in vivo may depend on plastome-encoded factor(s). These results suggest that plastome-encoded factors that cause specific protein degradation and/or abnormal processing might determine compartmental genetic incompatibility in plants. PMID:8544830

  7. Volatile fractions of landfill leachates and their effect on Chlamydomonas reinhardtii: In vivo chlorophyll a fluorescence

    SciTech Connect

    Brack, W.; Rottler, H.; Frank, H.

    1998-10-01

    Volatile organic compounds such as short-chain halogenated hydrocarbons and alkylated benzenes are widely used as solvents or as intermediates in the chemical industry, and some of them are fuel components. Dichloromethane, trichloroethene, 1,1,1-trichloroethane, and tetrachloroethene have been produced in amounts of 500,000 to 1 million t/year, 80 to 100% of which are released to the environment. The production of toluene, a major component of fuels for internal combustion engines, amounts to about 30 million t/year. A method for identification of toxic volatile constituents of landfill leachates is presented that combines bioassay-compatible sample preparation, chemical analysis, and a bioassay based on in vivo chlorophyll a fluorescence of the green alga Chlamydomonas reinhardtii. Two major pathways of toxicity were identified by comparing fluorescence patterns: specific toxicity of hydrogen sulfide, and narcotic action of nonreactive organic compounds. For quantification, the contributions of identified compounds were calculated using toxic units. The ecotoxicologic relevance of volatile fractions from hazardous waste leachates was shown.

  8. Temporal-spatial variations and developing trends of Chlorophyll-a in the Bohai Sea, China

    NASA Astrophysics Data System (ADS)

    Fu, Yanzhao; Xu, Shiguo; Liu, Jianwei

    2016-05-01

    The patterns of sea surface Chlorophyll-a (Chl-a) have regional and dynamic features. An understanding of the Chl-a dynamics and whether its trends in the past will be persistent in the future is important for restoration of ecosystem. Spatial and temporal variations of sea surface Chl-a concentrations in the Bohai Sea were investigated with data remotely sensed by MODIS from 2003 to 2014. The goals of this research are to identify the phytoplankton dynamics and detect their correlation with environmental changes and anthropogenic activities. Based on an indicator system built with Mann-Kendall Test and Hurst Exponent, our research shows that the Chl-a concentration in the surface layer is heterogeneous in both temporal and spatial scale. It is higher in costal zones, particularly near the Qinhuangdao coast. The occurrence of spring and summer blooms has a one-month time lag from south to north. An increasing trend that was persistent is evident offshore and a decreasing trend that was persistent is seen near the coast, which may indicate an expansion of eutrophication from coast to deep sea. The seasonality of the phytoplankton bloom is basically driven by vertical structure of water column. Climate and mariculture activity are significant correlated with the Chl-a trends. River discharge and suspended sediment also influence Chl-a.

  9. Spatial scale of chlorophyll-a concentration in Lake Taihu by using remote sensing images

    NASA Astrophysics Data System (ADS)

    Bao, Ying; Tian, Qingjiu

    2010-09-01

    Chlorophyll-a concentration is one of the most important indexes of Lake Eutrophication. Fine temporal and spatial resolution remote sensing images provide an effective way to monitor blue-green algae in Lake Taihu by studying the spatial distribution regularities of chla concentration. However, both low spatial resolution remote sensing images (e.g. MODIS) due to their heterogeneity and high or moderate spatial resolution remote sensing images (e.g. TM/ETM+) due to their low temporal resolution give rise to unsatisfactory estimate of chla concentration. Therefore, in this study, an effective method for estimating chla concentration using remote sensing images at different scales was developed. Chla concentration was inferred from Hyperion images at 30m resolution and MODIS images at 250m resolution. The spatial variability of Chla concentration was analyzed and Taihu Lake was divided into area with low variability and area with high variability. The quadratic polynomial (R2=0.8709) and linear (R2=0.7387) correlation was established. Finally, the obtained relationship between chla concentration estimate at different spatial scales were applied to correct the estimate from MODIS data.

  10. CHANGES IN CHLOROPHYLL A FLUORENSCENCE AND PIGMENT RATIOS DURING DIFFERENT GROWTH PHASES OF A UNICELLULAR MARINE CHEATOSEROS (BACILLARIOPHYCEAE) IN BATCH CULTURE

    EPA Science Inventory

    Photosystem II reaction centers per cell decreased as the cultures began to decline. The degree of inactivation increased daily as the cell numbers continued to decrease. The concentration of chlorophyll a per cell and the ratio of the major accessory pigments to chlorophyll a (e...

  11. Method 446.0: In Vitro Determination of Chlorophylls a, b, c + c and Pheopigments in 1 2Marine And Freshwater Algae by Visible Spectrophotometry

    EPA Science Inventory

    This method provides a procedure for determination of chlorophylls a (chl a), b (chl b), c + c 1 2 (chl c + c ) and pheopigments of chlorophyll a (pheo a) 1 2 found in marine and freshwater phytoplankton. Chlorophyllide a is determined as chl a. Visible wavelength spectrophotomet...

  12. Algorithms for the remote estimation of chlorophyll-a in the Chesapeake Bay

    NASA Astrophysics Data System (ADS)

    Ioannou, I.; Gilerson, A.; Ondrusek, M.; Foster, Robert; El-Habashi, Ahmed; Bastani, K.; Ahmed, S.

    2014-05-01

    Remote estimation of chlorophyll-a concentration [Chl-a] in the Chesapeake Bay from reflectance spectra is challenging because of the optical complexity and variability of the water composition as well as atmospheric corrections for this area. This work is focused on algorithms for near surface measurements. The performance and tuning of several well established global inversion algorithms that use the NIR and Blue-Green parts of the spectrum are analyzed together with recently proposed algorithm that use the Red-Green part of the spectrum. These algorithms are evaluated and tuned on our field data collected during summer 2013 field campaign in the in the Chesapeake Bay region . These data consist of a full range of water optical properties as well as chlorophyll concentrations and specific absorption spectra from in water samples. We then compare these algorithms with a multiband retrieval algorithm that was developed using neural networks (NN) and which was trained on simulated data generated through bio-optical modeling typical for a broad range of coastal water parameters, including those known for the Chesapeake Bay. This NN algorithm was then applied to our field measurements and used to retrieve the phytoplankton absorption at 443nm which was then related to [Chl-a]. In this process, special attention was paid to field data consistency in terms of both measured reflectance and [Chl-a] values, to avoid undesirable biases and trends. All algorithm retrievals were finally evaluated by several statistical indicators to arrive at their relative merits and potential for further improvements and application to satellite data.

  13. Vegetation stress detection through chlorophyll a + b estimation and fluorescence effects on hyperspectral imagery.

    PubMed

    Zarco-Tejada, P J; Miller, J R; Mohammed, G H; Noland, T L; Sampson, P H

    2002-01-01

    Physical principles applied to remote sensing data are key to successfully quantifying vegetation physiological condition from the study of the light interaction with the canopy under observation. We used the fluorescence-reflectance-transmittance (FRT) and PROSPECT leaf models to simulate reflectance as a function of leaf biochemical and fluorescence variables. A series of laboratory measurements of spectral reflectance at leaf and canopy levels and a modeling study were conducted, demonstrating that effects of chlorophyll fluorescence (CF) can be detected by remote sensing. The coupled FRT and PROSPECT model enabled CF and chlorophyll a + b (Ca + b) content to be estimated by inversion. Laboratory measurements of leaf reflectance (r) and transmittance (t) from leaves with constant Ca + b allowed the study of CF effects on specific fluorescence-sensitive indices calculated in the Photosystem I (PS-I) and Photosystem II (PS-II) optical region, such as the curvature index [CUR; (R675.R690)/R2(683)]. Dark-adapted and steady-state fluorescence measurements, such as the ratio of variable to maximal fluorescence (Fv/Fm), steady state maximal fluorescence (F'm), steady state fluorescence (Ft), and the effective quantum yield (delta F/F'm) are accurately estimated by inverting the FRT-PROSPECT model. A double peak in the derivative reflectance (DR) was related to increased CF and Ca + b concentration. These results were consistent with imagery collected with a compact airborne spectrographic imager (CASI) sensor from sites of sugar maple (Acer saccharum Marshall) of high and low stress conditions, showing a double peak on canopy derivative reflectance in the red-edge spectral region. We developed a derivative chlorophyll index (DCI; calculated as D705/D722), a function of the combined effects of CF and Ca + b content, and used it to detect vegetation stress. PMID:12371159

  14. Influence of Typhoon Matsa on Phytoplankton Chlorophyll-a off East China

    PubMed Central

    Shao, Jinchao; Han, Guoqi; Yang, Dezhou

    2015-01-01

    Typhoons can cause strong disturbance, mixing, and upwelling in the upper layer of the oceans. Rich nutrients from the subsurface layer can be brought to the euphotic layer, which will induce the phytoplankton to breed and grow rapidly. In this paper, we investigate the impact of an intense and fast moving tropical storm, Typhoon Matsa, on phytoplankton chlorophyll-a (Chl-a) concentration off East China. By using satellite remote sensing data, we analyze the changes of Chl-a concentration, Sea Surface Temperature (SST) and wind speed in the pre- and post-typhoon periods. We also give a preliminary discussion on the different responses of the Chl-a concentration between nearshore and offshore waters. In nearshore/coastal regions where nutrients are generally rich, the Chl-a maximum occurs usually at the surface or at the layer close to the surface. And, in offshore tropical oligotrophic oceans, the subsurface maxima of Chl-a exist usually in the stratified water column. In an offshore area east of Taiwan, the Chl-a concentration rose gradually in about two weeks after the typhoon. However, in a coastal area north of Taiwan high Chl-a concentration decreased sharply before landfall, rebounded quickly to some degree after landfall, and restored gradually to the pre-typhoon level in about two weeks. The Chl-a concentration presented a negative correlation with the wind speed in the nearshore area during the typhoon, which is opposite to the response in the offshore waters. The phenomena may be attributable to onshore advection of low Chl-a water, coastal downwelling and intensified mixing, which together bring pre-typhoon surface Chl-a downward in the coastal area. In the offshore area, the typhoon may trigger increase of Chl-a concentration through uptake of nutrients by typhoon-induced upwelling and entrainment mixing. PMID:26407324

  15. Field experiments of multi-channel oceanographic fluorescence lidar for oil spill and chlorophyll- a detection

    NASA Astrophysics Data System (ADS)

    Li, Xiaolong; Zhao, Chaofang; Ma, Youjun; Liu, Zhishen

    2014-08-01

    A Multi-channel Oceanographic Fluorescence Lidar (MOFL), with a UV excitation at 355 nm and multiple receiving channels at typical wavelengths of fluorescence from oil spills and chlorophyll- a (Chl- a), has been developed using the Laser-induced Fluorescence (LIF) technique. The sketch of the MOFL system equipped with a compact multi-channel photomultiplier tube (MPMT) is introduced in the paper. The methods of differentiating the oil fluorescence from the background water fluorescence and evaluating the Chl- a concentration are described. Two field experiments were carried out to investigate the field performance of the system, i.e., an experiment in coastal areas for oil pollution detection and an experiment over the Yellow Sea for Chl- a monitoring. In the coastal experiment, several oil samples and other fluorescence substances were used to analyze the fluorescence spectral characteristics for oil identification, and to estimate the thickness of oil films at the water surface. The experiment shows that both the spectral shape of fluorescence induced from surface water and the intensity ratio of two channels ( I 495/ I 405) are essential to determine oil-spill occurrence. In the airborne experiment, MOFL was applied to measure relative Chl- a concentrations in the upper layer of the ocean. A comparison of relative Chl- a concentration measurements by MOFL and the Moderate Resolution Imaging Spectroradiometer (MODIS) indicates that the two datasets are in good agreement. The results show that the MOFL system is capable of monitoring oil spills and Chl- a in the upper layer of ocean water.

  16. Influence of Typhoon Matsa on Phytoplankton Chlorophyll-a off East China.

    PubMed

    Zhao, Hui; Shao, Jinchao; Han, Guoqi; Yang, Dezhou; Lv, Jianhai

    2015-01-01

    Typhoons can cause strong disturbance, mixing, and upwelling in the upper layer of the oceans. Rich nutrients from the subsurface layer can be brought to the euphotic layer, which will induce the phytoplankton to breed and grow rapidly. In this paper, we investigate the impact of an intense and fast moving tropical storm, Typhoon Matsa, on phytoplankton chlorophyll-a (Chl-a) concentration off East China. By using satellite remote sensing data, we analyze the changes of Chl-a concentration, Sea Surface Temperature (SST) and wind speed in the pre- and post-typhoon periods. We also give a preliminary discussion on the different responses of the Chl-a concentration between nearshore and offshore waters. In nearshore/coastal regions where nutrients are generally rich, the Chl-a maximum occurs usually at the surface or at the layer close to the surface. And, in offshore tropical oligotrophic oceans, the subsurface maxima of Chl-a exist usually in the stratified water column. In an offshore area east of Taiwan, the Chl-a concentration rose gradually in about two weeks after the typhoon. However, in a coastal area north of Taiwan high Chl-a concentration decreased sharply before landfall, rebounded quickly to some degree after landfall, and restored gradually to the pre-typhoon level in about two weeks. The Chl-a concentration presented a negative correlation with the wind speed in the nearshore area during the typhoon, which is opposite to the response in the offshore waters. The phenomena may be attributable to onshore advection of low Chl-a water, coastal downwelling and intensified mixing, which together bring pre-typhoon surface Chl-a downward in the coastal area. In the offshore area, the typhoon may trigger increase of Chl-a concentration through uptake of nutrients by typhoon-induced upwelling and entrainment mixing. PMID:26407324

  17. Migration of Electronic Energy from Chlorophyll b to Chlorophyll a in Solutions

    PubMed Central

    Bauer, R. K.; Szalay, L.; Tombacz, E.

    1972-01-01

    Absorption, emission, and fluorescence excitation spectra of pure solutions of chlorophyll a (Chl a) and chlorophyll b (Chl b) in diethyl ether and of equimolecular mixed solutions of the two pigments, were determined at room temperature as functions of concentration (in the range from 5 × 10-6 M to 4 × 10-3 M) and of wavelength of the exciting light (in the regions 380-465 and 550-650 nm). The efficiency of energy transfer from Chl b to Chl a, derived from these data, was found to depend on the wavelength of exciting light. Furthermore, the transfer efficiency calculated from sensitization of Chl a fluorescence by Chl b was substantially smaller than that calculated from quenching of Chl b fluorescence by Chl a. Both these effects are tentatively explained as evidence of superposition of a “fast” energy transfer (taking place before the Boltzmann distribution of vibrational energy had been reached) upon the “delayed” transfer, which takes place after vibrational equilibration. The first-named mechanism is made possible by overlapping of the absorption bands of the two pigments; the second, by overlapping of the emission band of Chl b and the absorption band of Chl a. The first mechanism can lead to repeated transfer of excitation energy between pigment molecules, the second only to a one-time transfer from the donor to the acceptor. Both mechanisms could be of the same, second-order type, with the transfer rate proportional to r-6. An alternative is for the fast mechanism to be of the first order, with the transfer rate proportional to r-3, but spectroscopic evidence seems to make this alternative less probable. PMID:5037334

  18. Linking chlorophyll a fluorescence to photosynthesis for remote sensing applications: mechanisms and challenges.

    PubMed

    Porcar-Castell, Albert; Tyystjärvi, Esa; Atherton, Jon; van der Tol, Christiaan; Flexas, Jaume; Pfündel, Erhard E; Moreno, Jose; Frankenberg, Christian; Berry, Joseph A

    2014-08-01

    Chlorophyll a fluorescence (ChlF) has been used for decades to study the organization, functioning, and physiology of photosynthesis at the leaf and subcellular levels. ChlF is now measurable from remote sensing platforms. This provides a new optical means to track photosynthesis and gross primary productivity of terrestrial ecosystems. Importantly, the spatiotemporal and methodological context of the new applications is dramatically different compared with most of the available ChlF literature, which raises a number of important considerations. Although we have a good mechanistic understanding of the processes that control the ChlF signal over the short term, the seasonal link between ChlF and photosynthesis remains obscure. Additionally, while the current understanding of in vivo ChlF is based on pulse amplitude-modulated (PAM) measurements, remote sensing applications are based on the measurement of the passive solar-induced chlorophyll fluorescence (SIF), which entails important differences and new challenges that remain to be solved. In this review we introduce and revisit the physical, physiological, and methodological factors that control the leaf-level ChlF signal in the context of the new remote sensing applications. Specifically, we present the basis of photosynthetic acclimation and its optical signals, we introduce the physical and physiological basis of ChlF from the molecular to the leaf level and beyond, and we introduce and compare PAM and SIF methodology. Finally, we evaluate and identify the challenges that still remain to be answered in order to consolidate our mechanistic understanding of the remotely sensed SIF signal. PMID:24868038

  19. Estimation of chlorophyll-a concentration of different seasons in outdoor ponds using hyperspectral imaging.

    PubMed

    Wang, Lu; Pu, Hongbin; Sun, Da-Wen

    2016-01-15

    Chlorophyll a (Chl-a) is regarded as one of the important components to estimate water quality and sustainability of freshwater aquaculture operations. In the current study, a hyperspectral imaging (HSI) system was used to determine the effect of season models on the accuracy of Chl-a estimation in outdoor aquaculture ponds. A visible and near infrared hyperspectral imaging system (400-1000nm) was used to measure surface spectral reflectance (R) of water collected from outdoor ponds in four different seasons. Firstly, values of surface spectral reflectance (R) were amplified by a baseline correction (740nm). Two-band, three-band and four-band spectral reflectance were used to compute Chl-a concentration and a new cross band ratio algorithm with six wavelengths was proposed in the study. Results indicated that two-band model established based on reflectance ratio (R702/R666) had better performances for Chl-a prediction with determination coefficients (r(2)) of 0.908 than those by (R675(-1)-R691(-1))*R743 and (R675(-1)-R691(-1))/(R743(-1)-R691(-1)) models with r(2) of 0.902 and 0.896, respectively. Six optimal wavelengths (410, 682, 691, 966, 972, and 997) were identified using successive projections algorithm (SPA). The optimized regression model (R410(-1)-R966(-1))/(R682(-1)-R972(-1))/(R691(-1)-R997(-1)) showed best result with r(2) of 0.961 for Chl-a prediction. Model of cross band ratio algorithm with six wavelengths was mapped to each pixel in the image to display Chl-a component in outdoor ponds under four different seasons. The current study showed that it was feasible to use the HSI system for monitoring the influence of seasons for outdoor aquaculture water quality. PMID:26592628

  20. [Distribution of Chlorophyll-a and Eutrophication State in Tianchi Lake of Tianshan Mountains in Summer].

    PubMed

    Wang, Bin; Ma, Jian; Wang, Yin-ya; Yin, Xiang-jiang

    2015-07-01

    From June to August in 2014, the distributions of chlorophyll-a (Chl-a) and correlations with environmental factors were investigated, the eutrophication status and causes were discussed in Tianchi Lake of Tianshan Mountains. The results showed that the Chl-a concentrations ranged from 2. 11 to 4. 06 µg. L -1 with a mean value of (2. 8 ± 0. 69) µg . L-1 in summer, the vertical distribution of Chl-a in different monitoring zones had a similar characteristic that the Chl-a concentration in epilimnionis (2-12 m) was higher than those at the surface (0-2 m) and hypolimnion (below 12 m). The Chl-a concentration had significant negative correlations with depth and conductivity, significant positive correlations with water temperature, pH value, the concentration of dissolved oxygen, the cell density of algae and TP, and less correlation with TN. The mean concentrations of TN and TP in Tianchi Lake in summer were 0.27 mg . L-1 and 0.035 mg. L-1 respectively, both of which exceeded the international standards of general eutrophic lakes. The modified Carlson trophic state index was used to assess the eutrophication status of Tianchi Lake, which is currently at a moderate eutrophication level. The reasons might be the increased nutrients attributed to soil erosion, and algae blooms due to the changes in the composition of hydrobios. Therefore, it is important to use ecological restoration and management to protect the water quality and surrounding vegetation, which may mitigate the risk of eutrophication in Tianchi Lake. PMID:26489313

  1. Ultrastructure, molecular phylogenetics, and chlorophyll a content of novel cyanobacterial symbionts in temperate sponges.

    PubMed

    Erwin, Patrick M; López-Legentil, Susanna; Turon, Xavier

    2012-10-01

    Marine sponges often harbor photosynthetic symbionts that may enhance host metabolism and ecological success, yet little is known about the factors that structure the diversity, specificity, and nature of these relationships. Here, we characterized the cyanobacterial symbionts in two congeneric and sympatric host sponges that exhibit distinct habitat preferences correlated with irradiance: Ircinia fasciculata (higher irradiance) and Ircinia variabilis (lower irradiance). Symbiont composition was similar among hosts and dominated by the sponge-specific cyanobacterium Synechococcus spongiarum. Phylogenetic analyses of 16S-23S rRNA internal transcribed spacer (ITS) gene sequences revealed that Mediterranean Ircinia spp. host a specific, novel symbiont clade ("M") within the S. spongiarum species complex. A second, rare cyanobacterium related to the ascidian symbiont Synechocystis trididemni was observed in low abundance in I. fasciculata and likewise corresponded to a new symbiont clade. Symbiont communities in I. fasciculata exhibited nearly twice the chlorophyll a concentrations of I. variabilis. Further, S. spongiarum clade M symbionts in I. fasciculata exhibited dense intracellular aggregations of glycogen granules, a storage product of photosynthetic carbon assimilation rarely observed in I. variabilis symbionts. In both host sponges, S. spongiarum cells were observed interacting with host archeocytes, although the lower photosynthetic activity of Cyanobacteria in I. variabilis suggests less symbiont-derived nutritional benefit. The observed differences in clade M symbionts among sponge hosts suggest that ambient irradiance conditions dictate symbiont photosynthetic activity and consequently may mediate the nature of host-symbiont relationships. In addition, the plasticity exhibited by clade M symbionts may be an adaptive attribute that allows for flexibility in host-symbiont interactions across the seasonal fluctuations in light and temperature characteristic of

  2. Chemical determination of particulate nitrogen in San Francisco Bay. Nitrogen: chlorophyll a ratios in plankton

    USGS Publications Warehouse

    Hager, S.W.; Harmon, D.D.; Alpine, A.E.

    1984-01-01

    Particulate nitrogen (PN) and chlorophyll a (Chla) were measured in the northern reach of San Francisco Bay throughout 1980. The PN values were calculated as the differences between unfiltered and filtered (0??4 ??m) samples analyzed using the UV-catalyzed peroxide digestion method. The Chla values were measured spectrophotometrically, with corrections made for phaeopigments. The plot of all PN Chla data was found to be non-linear, and the concentration of suspended particulate matter (SPM) was found to be the best selector for linear subsets of the data. The best-fit slopes of PN Chla plots, as determined by linear regression (model II), were interpreted to be the N: Chla ratios of phytoplankton. The Y-intercepts of the regression lines were considered to represent easily-oxidizable detrital nitrogen (EDN). In clear water ( < 10 mg l-1 SPM), the N: Chla ratio was 1??07 ??g-at N per ??g Chla. It decreased to 0??60 in the 10-18 mg l-1 range and averaged 0??31 in the remaining four ranges (18-35, 35-65, 65-155, and 155-470 mg l-1). The EDN values were less than 1 ??g-at N l-1 in the clear water and increased monotonically to almost 12 ??g-at N l-1 in the highest SPM range. The N: Chla ratios for the four highest SPM ranges agree well with data for phytoplankton in light-limited cultures. In these ranges, phytoplankton-N averaged only 20% of the PN, while EDN averaged 39% and refractory-N 41%. ?? 1984.

  3. Relationship of Northeast Atlantic albacore juveniles with surface thermal and chlorophyll-a fronts

    NASA Astrophysics Data System (ADS)

    Sagarminaga, Y.; Arrizabalaga, H.

    2014-09-01

    When the spring seasonal warming starts, North Atlantic albacore (Thunnus alalunga) juveniles and pre-adults perform a trophic migration to the northeastern Atlantic, to the Bay of Biscay, and to the southeast of Ireland. During this migration, albacore juveniles are mainly exploited by Spanish trolling and baitboat fleets. The present study analyzes the relationship between the albacore spatio-temporal distribution and the upper surface horizontal fronts in their migration paths and destinations. For this, albacore catches from personal fishing logbooks from Basque trolling and live-bait fleets and daily MODIS AQUA Chlorophyll-a and SST products covering the period 2003-2005 have being used. Gradients have been calculated with the front algorithm proposed by Belkin and O'Reilly (2009). The approach used to study the relationship of catches location with frontal areas is based in the comparison of distributions of gradient magnitude around catch locations versus gradient magnitudes in a Monthly Occupation Area. The results obtained show that there is a high spatio- temporal variability of SST and Chl-a fronts in the area. SST and Chl-a fronts are not coincident in time or in space. However, there is a clear seasonal pattern of SST and Chl-a frontal activity in the area with a peak in July for SST gradient magnitudes and a peak in April for Chl-a gradient magnitudes. The relationship of albacore juvenile catches with high gradient magnitude areas is different according to the months and fleets analysed. In general, there is no evidence of consistent adherence of albacore catches to areas with higher SST gradients. However, results suggest a potential association between both fleets catches and Chl-a high gradient magnitude areas in August and September.

  4. Genetic variability and heritability of chlorophyll a fluorescence parameters in Scots pine (Pinus sylvestris L.).

    PubMed

    Čepl, Jaroslav; Holá, Dana; Stejskal, Jan; Korecký, Jiří; Kočová, Marie; Lhotáková, Zuzana; Tomášková, Ivana; Palovská, Markéta; Rothová, Olga; Whetten, Ross W; Kaňák, Jan; Albrechtová, Jana; Lstibůrek, Milan

    2016-07-01

    Current knowledge of the genetic mechanisms underlying the inheritance of photosynthetic activity in forest trees is generally limited, yet it is essential both for various practical forestry purposes and for better understanding of broader evolutionary mechanisms. In this study, we investigated genetic variation underlying selected chlorophyll a fluorescence (ChlF) parameters in structured populations of Scots pine (Pinus sylvestris L.) grown on two sites under non-stress conditions. These parameters were derived from the OJIP part of the ChlF kinetics curve and characterize individual parts of primary photosynthetic processes associated, for example, with the exciton trapping by light-harvesting antennae, energy utilization in photosystem II (PSII) reaction centers (RCs) and its transfer further down the photosynthetic electron-transport chain. An additive relationship matrix was estimated based on pedigree reconstruction, utilizing a set of highly polymorphic single sequence repeat markers. Variance decomposition was conducted using the animal genetic evaluation mixed-linear model. The majority of ChlF parameters in the analyzed pine populations showed significant additive genetic variation. Statistically significant heritability estimates were obtained for most ChlF indices, with the exception of DI0/RC, φD0 and φP0 (Fv/Fm) parameters. Estimated heritabilities varied around the value of 0.15 with the maximal value of 0.23 in the ET0/RC parameter, which indicates electron-transport flux from QA to QB per PSII RC. No significant correlation was found between these indices and selected growth traits. Moreover, no genotype × environment interaction (G × E) was detected, i.e., no differences in genotypes' performance between sites. The absence of significant G × E in our study is interesting, given the relatively low heritability found for the majority of parameters analyzed. Therefore, we infer that polygenic variability of these indices is

  5. Assessing the influence of watershed characteristics on chlorophyll a in waterbodies at global and regional scales

    USGS Publications Warehouse

    Woelmer, Whitney; Kao, Yu-Chun; Bunnell, David; Deines, Andrew M.; Bennion, David; Rogers, Mark W.; Brooks, Colin N.; Sayers, Michael J.; Banach, David M.; Grimm, Amanda G.; Shuchman, Robert A.

    2016-01-01

    Prediction of primary production of lentic water bodies (i.e., lakes and reservoirs) is valuable to researchers and resource managers alike, but is very rarely done at the global scale. With the development of remote sensing technologies, it is now feasible to gather large amounts of data across the world, including understudied and remote regions. To determine which factors were most important in explaining the variation of chlorophyll a (Chl-a), an indicator of primary production in water bodies, at global and regional scales, we first developed a geospatial database of 227 water bodies and watersheds with corresponding Chl-a, nutrient, hydrogeomorphic, and climate data. Then we used a generalized additive modeling approach and developed model selection criteria to select models that most parsimoniously related Chl-a to predictor variables for all 227 water bodies and for 51 lakes in the Laurentian Great Lakes region in the data set. Our best global model contained two hydrogeomorphic variables (water body surface area and the ratio of watershed to water body surface area) and a climate variable (average temperature in the warmest model selection criteria to select models that most parsimoniously related Chl-a to predictor variables quarter) and explained ~ 30% of variation in Chl-a. Our regional model contained one hydrogeomorphic variable (flow accumulation) and the same climate variable, but explained substantially more variation (58%). Our results indicate that a regional approach to watershed modeling may be more informative to predicting Chl-a, and that nearly a third of global variability in Chl-a may be explained using hydrogeomorphic and climate variables.

  6. Measuring chlorophyll a and /sup 14/C-labeled photosynthate in aquatic angiosperms by the use of a tissue solubilizer

    SciTech Connect

    Beer, S.; Stewart, A.J.; Wetzel, R.G.

    1982-01-01

    A compound that quantitatively correlated with chlorophyll a could be measured fluorometrically in the extracts of leaves of three aquatic angiosperms (Myriophyllum heterophyllum Michx., Potamogeton crispus L., Elodea canadensis Michx.) treated with the tissue solubilizer BTS-450. Fluorescent characteristics of the solubilized plant tissues were stable for several weeks in the dark at temperatures up to 60/sup 0/C but rapidly degraded in sunlight or when acidified. /sup 14/C-Labeled photosynthate, which had been fixed by leaf discs during 1- to 10-hour exposure to H/sup 14/CO/sub 3/, was also readily extracted by the tissue solubilizer. Solubilizer extraction can, therefore, be use to determine both chlorophyll a content and /sup 14/C incorporation rates in the same leaf sample. The method is practical, because no grinding is required, the fluorescent characteristics of the extracts are stable, and analyses can be performed with very little plant material (about 3 milligrams).

  7. Remotely-sensed chlorophyll a observations of the northern Red Sea indicate seasonal variability and influence of coastal reefs

    NASA Astrophysics Data System (ADS)

    Acker, James; Leptoukh, Gregory; Shen, Suhung; Zhu, Tong; Kempler, Steven

    The biological dynamics of the open northern Red Sea (21.5°-27.5° N, 33.5°-40° E) have not been studied extensively, due in part to both the inaccessibility of this desert region and political considerations. Remotely-sensed chlorophyll a data therefore provide a framework to investigate the primary patterns of biological activity in this oceanic basin. Monthly chlorophyll a data from the 8-year Sea-viewing Wide Field-of-View sensor (SeaWiFS) mission, and data from the Moderate Resolution Imaging Spectroradiometer (MODIS), were analyzed with the Goddard Earth Sciences Data and Information Services Center (GES DISC) online data analysis system "Giovanni". The data indicate that despite the normal low chlorophyll a concentrations (0.1-0.2 mg m - 3 ) in these oligotrophic waters, there is a characteristic seasonal bloom in March-April in the northernmost open Red Sea (24° to 27.5° N) concurrent with minimum sea surface temperature. The location of the highest chlorophyll concentrations is consistent with a linear box model [Eshel, G., and Naik, N.H., 1997. Climatological coastal jet collision, intermediate water formation, and the general circulation of the Red Sea. J. Phys. Oceanogr. 27(7), 1233-1257.] of Red Sea circulation. Two years in the data set exhibited a different seasonal cycle consisting of a relatively weak northern spring bloom and elevated chlorophyll concentrations to the south (21.5° to 24° N). The data also indicate that large coral reef complexes may be sources of either nutrients or chlorophyll-rich detritus and sediment, enhancing chlorophyll a concentration in waters adjacent to the reefs.

  8. Complex interactions among nutrients, chlorophyll-a, and microcystins in three stormwater wet detention basins with floating treatment wetlands.

    PubMed

    Hartshorn, Nicholas; Marimon, Zachary; Xuan, Zhemin; Cormier, Jessica; Chang, Ni-Bin; Wanielista, Martin

    2016-02-01

    Stormwater wet detention ponds hold a permanent pool of water and offer many beneficial uses including flood mitigation, pollution prevention, downstream erosion control, increased aesthetics, and recreational uses. Although the removal of nutrients is generally low for stormwater wet detention ponds in urban areas, floating treatment wetlands (FTWs) can be installed to offer an innovative solution toward naturally removing excess nutrients and aiding in stormwater management. To improve the stormwater reuse potential, this study assessed nutrient, microcystin, and chlorophyll-a interactions in three Florida stormwater wet detention ponds with recently implemented FTWs. Both episodic (storm events) and routine (non-storm events) sampling campaigns were carried out at the three ponds located in Ruskin, Gainesville, and Orlando. The results showed a salient negative correlation between total phosphorus and microcystin concentrations for both storm and non-storm events across all three ponds. The dominant nutrient species in correlation seemed to be total phosphorus, which correlated positively with chlorophyll-a concentrations at all ponds and sampling conditions, with the exception of Orlando non-storm events. These results showed a correlation conditional to the candidate pond and sampling conditions for microcystin and chlorophyll-a concentrations. PMID:26386430

  9. Synthesis of methyl (13(2)R/S)-alkyl-pyropheophorbide a and a non-epimerized chlorophyll a mimic.

    PubMed

    Ogasawara, Shin; Tamiaki, Hitoshi

    2015-10-15

    The (13(2)R/S)-methoxycarbonyl group of methyl pheophorbides a/a' (chlorophyll a/a' derivatives) was converted to methyl, ethyl, propyl, and isopropyl groups through the C13(2)-alkylation under basic conditions followed by pyrolysis in 2,4,6-collidine with lithium iodide. All the resulting products, methyl 13(2)-alkyl-pyropheophorbides a, predominantly gave the (13(2)R)-stereoisomers with about one tenth of the (13(2)S)-epimers. Their stereochemistry was determined by 1D/2D NMR and their optical properties were characterized by visible absorption and circular dichroism spectroscopy. Methyl (13(2)R)-propyl-pyropheophorbide a was converted to (13(2)R)-propyl-pyrochlorophyll a by ester exchanging and magnesium chelating reactions. The synthetic chlorophyll a analogue showed non-epimerization at the 13(2)-position in pyridine-d5 at 40°C, while naturally occurring chlorophyll a was easily epimerized under the same conditions to give its epimeric mixture. PMID:26404409

  10. In Vivo Assessment of Cold Tolerance through Chlorophyll-a Fluorescence in Transgenic Zoysiagrass Expressing Mutant Phytochrome A

    PubMed Central

    Gururani, Mayank Anand; Venkatesh, Jelli; Ganesan, Markkandan; Strasser, Reto Jörg; Han, Yunjeong; Kim, Jeong-Il; Lee, Hyo-Yeon; Song, Pill-Soon

    2015-01-01

    Chlorophyll-a fluorescence analysis provides relevant information about the physiology of plants growing under abiotic stress. In this study, we evaluated the influence of cold stress on the photosynthetic machinery of transgenic turfgrass, Zoysia japonica, expressing oat phytochrome A (PhyA) or a hyperactive mutant phytochrome A (S599A) with post-translational phosphorylation blocked. Biochemical analysis of zoysiagrass subjected to cold stress revealed reduced levels of hydrogen peroxide, increased proline accumulation, and enhanced specific activities of antioxidant enzymes compared to those of control plants. Detailed analyses of the chlorophyll-a fluorescence data through the so-called OJIP test exhibited a marked difference in the physiological status among transgenic and control plants. Overall, these findings suggest an enhanced level of cold tolerance in S599A zoysiagrass cultivars as reflected in the biochemical and physiological analyses. Further, we propose that chlorophyll-a fluorescence analysis using OJIP test is an efficient tool in determining the physiological status of plants under cold stress conditions. PMID:26010864

  11. An improved algorithm for retrieving chlorophyll-a from the Yellow River Estuary using MODIS imagery.

    PubMed

    Chen, Jun; Quan, Wenting

    2013-03-01

    In this study, an improved Moderate-Resolution Imaging Spectroradiometer (MODIS) ocean chlorophyll-a (chla) 3 model (IOC3M) algorithm was developed as a substitute for the MODIS global chla concentration estimation algorithm, OC3M, to estimate chla concentrations in waters with high suspended sediment concentrations, such as the Yellow River Estuary, China. The IOC3M algorithm uses [Formula: see text] to substitute for switching the two-band ratio of max [R (rs) (443 nm), R (rs) (488 nm)]/R (rs) (551 nm) of the OC3M algorithm. In the IOC3M algorithm, the absorption coefficient of chla can be isolated as long as reasonable bands are selected. The performance of IOC3M and OC3M was calibrated and validated using a bio-optical data set composed of spectral upwelling radiance measurements and chla concentrations collected during three independent cruises in the Yellow River Estuary in September of 2009. It was found that the optimal bands of the IOC3M algorithm were λ(1) = 443 nm, λ(2) = 748 nm, λ(3) = 551 nm, and λ(4) = 870 nm. By comparison, the IOC3M algorithm produces superior performance to the OC3M algorithm. Using the IOC3M algorithm in estimating chla concentrations from the Yellow River Estuary decreases 1.03 mg/m(3) uncertainty from the OC3M algorithm. Additionally, the chla concentration estimated from MODIS data reveals that more than 90 % of the water in the Yellow River Estuary has a chla concentration lower than 5.0 mg/m(3). The averaged chla concentration is close to the in situ measurements. Although the case study presented herein is unique, the modeling procedures employed by the IOC3M algorithm can be useful in remote sensing to estimate the chla concentrations of similar aquatic environments. PMID:22707149

  12. Size-fractionated Chlorophyll a biomass in the northern South China Sea in summer 2014

    NASA Astrophysics Data System (ADS)

    Liu, Haijiao; Xue, Bing; Feng, Yuanyuan; Zhang, Rui; Chen, Mianrun; Sun, Jun

    2015-11-01

    Spatial distribution of phaeopigment and size-fractionated chlorophyll a (Chl a) concentrations were examined in relation to hydrographic conditions in the northern South China Sea (NSCS) during a survey from 20 August to 12 September, 2014. The total Chl a concentration varied from 0.006 to 1.488 µg/L with a mean value of 0.259±0.247 (mean±standard deviation) µg/L. Chl a concentration was generally higher in shallow water (<200 m) than in deep water (>200 m), with mean values of 0.364±0.311 µg/L and 0.206±0.192 µg/L respectively. Vertically, the maximum total Chl a concentration appeared at depths of 30-50 m and gradually decreased below 100 m. The size-fractionated Chl a concentrations of grid stations and time-series stations (SEATS and J4) were determined, with values of pico- (0.7-2 µm), nano- (2-20 µm) and micro-plankton (20-200 µm) ranging from 0.001-0.287 (0.093±0.071 µg/L), 0.004-1.149 (0.148±0.192 µg/L) and 0.001-0.208 (0.023±0.036 µg/L), respectively. Phaeopigment concentrations were determined at specific depths at ten stations, except for at station A9, and varied from 0.007 to 0.572 (0.127±0.164) µg/L. Nano-and pico-plankton were the major contributors to total phytoplankton biomass, accounting for 50.99%±15.01% and 39.30%±15.41%, respectively, whereas microplankton only accounted for 9.39%±8.66%. The results indicate that the contributions of microplankton to total Chl a biomass were less important than picoplankton or nanoplankton in the surveyed NSCS. Different sized-Chl a had similar spatial patterns, with peak values all observed in subsurface waters (30-50 m). The summer monsoon, Kuroshio waters, Zhujiang (Pearl) River plume, and hydrological conditions are speculated to be the factors controlling the abundance and spatial heterogeneity of Chl a biomass in the NSCS.

  13. Salinity predicts the distribution of chlorophyll a spring peak in the southern North Sea continental waters

    NASA Astrophysics Data System (ADS)

    Desmit, Xavier; Ruddick, Kevin; Lacroix, Geneviève

    2015-09-01

    In the North Sea, the coastal waters of Belgium and The Netherlands regularly exhibit intense spring phytoplankton blooms where species such as Phaeocystis recurrently form a potential ecological nuisance. In the Belgian and Dutch continental shelves (BCS and DCS), we observe a direct correlation between the chlorophyll a spring maximum (Chlmax) and the nutrients (DIN and DIP) available for the bloom. As the nutrients are themselves strongly correlated with salinity, a rationale is developed to predict Chlmax from winter salinity. The proposed rationale is first tested in a theoretical case with a 3D-biogeochemical model (3D-MIRO&CO). The method is then applied to independent sets of in situ observations over 20 years in the BCS and the DCS, and to continuous FerryBox data in April 2008. Linear regressions explain the relationships between winter nutrients and winter salinity (R2 = 0.88 to 0.97 with model results, and R2 = 0.83 to 0.96 with in situ data). The relationship between Chlmax and the available nutrients across the salinity gradient is also explained by yearly linear regressions (R2 = 0.82 to 0.94 with model results, and R2 = 0.46 to 0.98 with in situ data). Empirical 'DIP requirement' and 'DIN requirement' for the spring biomass bloom formation are derived from the latter relationships. They depend i.a. on the losses from phytoplankton during the spring bloom formation, and therefore show some interannual variability (8-12% for DIP and 13-20% for DIN). The ratio between nutrient requirements allows predicting in winter which nutrient will eventually limit the spring biomass bloom along the salinity gradient. DIP will generally be limiting in the coastal zone, whereas DIN will generally be limiting offshore, the switch occurring typically at salinity 33.5 in the BCS and 33.6 in the DCS. N reduction should be prioritized to limit Phaeocystis in the coastal zone, with target winter DIN:DIP ratios below 34.4 molN molP-1 in the BCS, or 28.6 molN molP- 1 in

  14. Size-fractionated Chlorophyll a biomass in the northern South China Sea in summer 2014

    NASA Astrophysics Data System (ADS)

    Liu, Haijiao; Xue, Bing; Feng, Yuanyuan; Zhang, Rui; Chen, Mianrun; Sun, Jun

    2016-07-01

    Spatial distribution of phaeopigment and size-fractionated chlorophyll a (Chl a) concentrations were examined in relation to hydrographic conditions in the northern South China Sea (NSCS) during a survey from 20 August to 12 September, 2014. The total Chl a concentration varied from 0.006 to 1.488 µg/L with a mean value of 0.259±0.247 (mean±standard deviation) µg/L. Chl a concentration was generally higher in shallow water (<200 m) than in deep water (>200 m), with mean values of 0.364±0.311 µg/L and 0.206±0.192 µg/L respectively. Vertically, the maximum total Chl a concentration appeared at depths of 30-50 m and gradually decreased below 100 m. The size-fractionated Chl a concentrations of grid stations and time-series stations (SEATS and J4) were determined, with values of pico- (0.7-2 µm), nano- (2-20 µm) and micro-plankton (20-200 µm) ranging from 0.001-0.287 (0.093±0.071 µg/L), 0.004-1.149 (0.148±0.192 µg/L) and 0.001-0.208 (0.023±0.036 µg/L), respectively. Phaeopigment concentrations were determined at specific depths at ten stations, except for at station A9, and varied from 0.007 to 0.572 (0.127±0.164) µg/L. Nano-and pico-plankton were the major contributors to total phytoplankton biomass, accounting for 50.99%±15.01% and 39.30%±15.41%, respectively, whereas microplankton only accounted for 9.39%±8.66%. The results indicate that the contributions of microplankton to total Chl a biomass were less important than picoplankton or nanoplankton in the surveyed NSCS. Different sized-Chl a had similar spatial patterns, with peak values all observed in subsurface waters (30-50 m). The summer monsoon, Kuroshio waters, Zhujiang (Pearl) River plume, and hydrological conditions are speculated to be the factors controlling the abundance and spatial heterogeneity of Chl a biomass in the NSCS.

  15. Oceanic And Terrestrial Controls On Chlorophyll -a Abundance Around The Island Of Okinawa, Japan

    NASA Astrophysics Data System (ADS)

    Ikema, T.; Bryant, R. G.; Bigg, G. R.

    2007-12-01

    This research aims to understand key factors affecting ocean surface chlorophyll-a (Chl-a) blooms at a range of scales (both regional and near the coastal zone) around the Island of Okinawa in the western Pacific. The study region is characterised by both the actions of the Kuroshio Current (which brings warm water) and the Asian Monsoon (which provides moist southwest winds in summer and dry northern winds in winter). Due to these influences, Okinawa has a subtropical climate, with a rainy season in the summer months (MJ), and prevailing northerly winds in winter (NDJ). In order to better understand factors which may influence the timing and magnitude of Chl-a blooms in the vicinity of Okinawa, we applied empirical orthogonal function (EOF) analysis to a time series of AVHRR (monthly mean SST from 1985-2006) and SeaWIFS (monthly mean Chl-a from 1998 to 2006) data over two different spatial scales: domain 1 (D1) - a region of the ocean southeast of Kuroshio, and domain 2 (D2) - a sub-region near coastline focused on Okinawa itself. The first EOF mode of SST in regions D1 and D2 (which accounted for more than 90 % in each domain) showed a clear radiation-driven annual cycle: high SST in summer and low SST in winter. The first EOF mode of Chl-a in D1 (which accounted for 51 %) also demonstrated an annual cycle, but in this instance one that mirrored that of SST (i.e. low Chl-a in summer and high Chl-a in winter). The first mode Chl-a EOF in D2 (accounting for 63 % of the total variance) also has a similar annual cycle, displaying a significant correlation (r=0.75, p<0.001) with northerly wind magnitudes, lagged by 2 months, suggesting that the winter monsoon is a major control on the observed Chl-a bloom. However, extreme events such as typhoons can also cause a Chl-a bloom around the coast. As a result of further analysis of daily Chl-a data along the western coastline of Okinawa, it was found that some of the peaks of Chl-a were closely correlated with river

  16. Satellite-based estimation of chlorophyll-a concentration in turbid productive waters

    NASA Astrophysics Data System (ADS)

    Moses, Wesley Jeremiah

    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 are preferable. Three-band and two-band NIR-red models based on the spectral channels of MODIS and MERIS satellites have been tested for numerous datasets collected with field spectrometers from inland, coastal, and estuarine waters. The NIR-red models, especially the two-band model with MERIS wavebands, gave consistently highly accurate estimates of chl- a concentration in waters from different geographic locations with widely varying biophysical characteristics, without the need to re-parameterize the algorithms for each different water body. The MODIS NIR-red model can be used to estimate moderate-to-high chl-a concentrations. The NIR-red models were applied to airborne AISA data acquired over several lakes in Nebraska on different days with non-uniform atmospheric conditions. Without atmospheric correction, the NIR-red models showed a close correlation with chl-a concentration for each image. With an effective relative correction for the non-uniform atmospheric effects on the multi-temporal images, the NIR-red models were shown to have a close correlation with chl- a concentration, with uniform slope and offset, for the whole dataset. The models were also applied to MODIS and MERIS images. Reliable results were obtained from the MERIS NIR-red models. Calibrated MERIS NIR-red algorithms were

  17. From the shape of the vertical profile of in vivo fluorescence to Chlorophyll-a concentration

    NASA Astrophysics Data System (ADS)

    Mignot, A.; Claustre, H.; D'Ortenzio, F.; Xing, X.; Poteau, A.; Ras, J.

    2011-04-01

    In vivo fluorescence of Chlorophyll-a (Chl-a) is a potentially useful property to study the vertical distribution of phytoplankton biomass. However the technique is presently not fully exploited as it should be, essentially because of the difficulties in converting the fluorescence signal into an accurate Chl-a concentration. These difficulties arise noticeably from natural variations in the Chl-a fluorescence relationship, which is under the control of community composition as well as of their nutrient and light status. As a consequence although vertical profiles of fluorescence are likely the most recorded biological property in the open ocean, the corresponding large databases are underexploited. Here with the aim to convert a fluorescence profile into a Chl-a concentration profile, we test the hypothesis that the Chl-a concentration can be gathered from the sole knowledge of the shape of the fluorescence profile. We analyze a large dataset from 18 oceanographic cruises conducted in case-1 waters from the highly stratified hyperoligotrophic waters (surface Chl-a = 0.02 mg m-3) of the South Pacific Gyre to the eutrophic waters of the Benguela upwelling (surface Chl-a = 32 mg m-3) and including the very deep mixed waters in the North Atlantic (Mixed Layer Depth = 690 m). This dataset encompasses more than 700 vertical profiles of Chl-a fluorescence as well as accurate estimations of Chl-a by High Performance Liquid Chromatography (HPLC). Two typical fluorescence profiles are identified, the uniform profile, characterized by a homogeneous layer roughly corresponding to the mixed layer, and the non-uniform profile, characterized by the presence of a Deep Chlorophyll Maximum. Using appropriate mathematical parameterizations, a fluorescence profile is subsequently represented by 3 or 5 shape parameters for uniform or non-uniform profiles, respectively. For both situations, an empirical model is developed to predict the "true" Chl-a concentration from these shape

  18. From the shape of the vertical profile of in vivo fluorescence to Chlorophyll-a concentration

    NASA Astrophysics Data System (ADS)

    Mignot, A.; Claustre, H.; D'Ortenzio, F.; Xing, X.; Poteau, A.; Ras, J.

    2011-08-01

    In vivo fluorescence of Chlorophyll-a (Chl-a) is a potentially useful property to study the vertical distribution of phytoplankton biomass. However the technique is presently not fully exploited as it should be, essentially because of the difficulties in converting the fluorescence signal into an accurate Chl-a concentration. These difficulties arise noticeably from natural variations in the Chl-a fluorescence relationship, which is under the control of community composition as well as of their nutrient and light status. As a consequence, although vertical profiles of fluorescence are likely the most recorded biological property in the open ocean, the corresponding large databases are underexploited. Here with the aim to convert a fluorescence profile into a Chl-a concentration profile, we test the hypothesis that the Chl-a concentration can be gathered from the sole knowledge of the shape of the fluorescence profile. We analyze a large dataset from 18 oceanographic cruises conducted in case-1 waters from the highly stratified hyperoligotrophic waters (surface Chl-a = 0.02 mg m-3) of the South Pacific Gyre to the eutrophic waters of the Benguela upwelling (surface Chl-a = 32 mg m-3) and including the very deep mixed waters in the North Atlantic (Mixed Layer Depth = 690 m). This dataset encompasses more than 700 vertical profiles of Chl-a fluorescence as well as accurate estimations of Chl-a by High Performance Liquid Chromatography (HPLC). Two typical fluorescence profiles are identified, the uniform profile, characterized by a homogeneous layer roughly corresponding to the mixed layer, and the non-uniform profile, characterized by the presence of a Deep Chlorophyll Maximum. Using appropriate mathematical parameterizations, a fluorescence profile is subsequently represented by 3 or 5 shape parameters for uniform or non-uniform profiles, respectively. For both situations, an empirical model is developed to predict the "true" Chl-a concentration from these shape

  19. Relative impact of seasonal and oceanographic drivers on surface chlorophyll a along a Western Boundary Current

    NASA Astrophysics Data System (ADS)

    Everett, Jason D.; Baird, Mark E.; Roughan, Moninya; Suthers, Iain M.; Doblin, Martina A.

    2014-01-01

    Strengthening Western Boundary Currents (WBCs) advect warm, low nutrient waters into temperate latitudes, displacing more productive waters. WBCs also influence phytoplankton distribution and growth through current-induced upwelling, mesoscale eddy intrusion and seasonal changes in strength and poleward penetration. Here we examine dynamics of chlorophyll a (Chl. a) in the western Pacific Ocean, a region strongly influenced by the East Australian Current (EAC). We interpreted a spatial and temporal analysis of satellite-derived surface Chl. a, using a hydrodynamic model, a wind-reanalysis product and an altimetry-derived eddy-census. Our analysis revealed regions of persistently elevated surface Chl. a along the continental shelf and showed that different processes have a dominant effect in different locations. In the northern and central zones, upwelling events tend to regulate surface Chl. a patterns, with peaks in phytoplankton biomass corresponding to two known upwelling locations south of Cape Byron (28.5°S) and Smoky Cape (31°S). Within the central EAC separation zone, positive surface Chl. a anomalies occurred 65% of the time when both wind-stress (τw) and bottom-stress (τB) were upwelling-favourable, and only 17% of the time when both were downwelling-favourable. The interaction of wind and the EAC was a critical driver of surface Chl. a dynamics, with upwelling-favourable τW resulting in a 70% increase in surface Chl. a at some locations, when compared to downwelling-favourable τW . In the southern zone, surface Chl. a was driven by a strong seasonal cycle, with phytoplankton biomass increasing up to 152% annually each spring. The Stockton Bight region (32.25-33.25°S) contained ⩾20% of the total shelf Chl. a on 27% of occasions due to its location downstream of upwelling locations, wide shelf area and reduced surface velocities. This region is analogous to productive fisheries regions in the Aghulus Current (Natal Bight) and Kuroshio Current

  20. Reference Ranges & What They Mean

    MedlinePlus

    ... be limited. Home Visit Global Sites Search Help? Reference Ranges and What They Mean Share this page: Was this page helpful? Overview | Reference range defined | Where are the reference ranges? | Limits ...

  1. Highs and lows: The effect of differently sized freshwater inflows on estuarine carbon, nitrogen, phosphorus, bacteria and chlorophyll a dynamics

    NASA Astrophysics Data System (ADS)

    Hitchcock, James N.; Mitrovic, Simon M.

    2015-04-01

    Freshwater inflows play a key role in the delivery of organic carbon to estuaries. However, our understanding of the dynamics between discharge and carbon globally is limited. In this study we performed a 30-month monitoring study on the Bega and Clyde River estuaries, Australia, to understand the influence that discharge had on carbon, nitrogen, phosphorus, bacteria and chlorophyll a dynamics. We hypothesised that 1) discharge would be the most important factor influencing carbon and nutrient concentrations, though during low flows chlorophyll a would also be positively related to carbon, 2) bacteria would be related to dissolved organic carbon (DOC), and chlorophyll a to temperature, nitrogen and phosphorus, and 3) that concentrations of carbon, nitrogen, phosphorus, bacterial biomass and chlorophyll a would be significantly different between large 'flood flows', smaller 'fresh flows' and base flow conditions. We found that discharge was always the most important factor influencing carbon and nutrient concentrations, and that primary production appeared to have little influence on the variation in DOC concentration even during base flow conditions. We suggest this relationship is likely due to highly episodic discharge that occurred during the study period. Bacteria were related to DOC in the lower estuary sites, but phosphorus in the upper estuary. We suggest this is likely due to the input of bioavailable carbon in the upper estuary leading bacteria to be P limited, which changes downstream to carbon limitation as DOC becomes more refractory. Chlorophyll a was positively related to temperature but not nutrients, which we suggest may be due to competition with bacteria for phosphorus in the upper estuary. Carbon, nitrogen and phosphorus concentrations were different under flood, fresh and base flow conditions, though these differences sometimes varied between estuary locations for different resources. Overall, the results demonstrate that discharge plays an

  2. Estimation of the depth of sunlight penetration in natural waters for the remote sensing of chlorophyll a via in vivo fluorescence

    NASA Technical Reports Server (NTRS)

    Gordon, H. R.

    1979-01-01

    In attempting to measure remotely the constituents of the ocean through spectral analysis of diffusely reflected sunlight, it is important to know the depth over which constituent concentrations can be estimated. Recently, considerable interest has been generated in the use of sunlight-excited fluorescence of chlorophyll a contained in photoplankton (in vivo) to determine remotely the chlorophyll a concentration in surface waters. In the present paper an estimate is provided for the depth to which chlorophyll a concentration can be determined from observations of the fluorescence.

  3. Defining Airflow Obstruction

    PubMed Central

    Eschenbacher, William L.

    2016-01-01

    Airflow obstruction has been defined using spirometric test results when the forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC) ratio is below a fixed cutoff (<70%) or lower limits of normal (LLN) from reference equations that are based on values from a normal population. However, similar to other positive or abnormal diagnostic test results that are used to identify the presence of disease, perhaps airflow obstruction should be defined based on the values of FEV1/FVC for a population of individuals with known disease such as chronic obstructive pulmonary disease (COPD). Unfortunately, we do not know such a distribution of values of FEV1/FVC for patients with COPD since there is no gold standard for this syndrome or condition. Yet, we have used this physiologic definition of airflow obstruction based on a normal population to identify patients with COPD. In addition, we have defined airflow obstruction as either being present or absent. Instead, we should use a different approach to define airflow obstruction based on the probability or likelihood that the airflow obstruction is present which in turn would give us the probability or likelihood of a disease state such as COPD. PMID:27239557

  4. Theoretical study of chlorophyll a hydrates formation in aqueous organic solvents.

    PubMed

    Ben Fredj, Arij; Ruiz-López, Manuel F

    2010-01-14

    A theoretical analysis of chlorophyll a (Chla) hydration processes in aqueous organic solvents has been carried out by means of quantum chemistry calculations. A detailed knowledge of the thermodynamics of these processes is fundamental in order to better understand the organization of chlorophyll molecules in vivo, specifically the structure of chlorophyll pairs in photosystems I and II. In the present work, we assumed a Chla model in which the phytyl chain is replaced by a methyl group. Calculations were performed at the B3LYP/6-31G(d) level corrected for basis set superposition errors and dispersion interaction energy. This computational scheme was previously shown to provide data close to MP2/6-311++(2d,2p) results. Solvents effects were taken into account using either continuum (for nonpolar solvents) or discrete-continuum (for polar coordinating solvents) methods. In the latter case, we first examined the structure of Chla in rigorously dry solutions. Two types of solvents were characterized according to Mg-atom coordination: In type I solvents (acetone, acetonitrile, DMSO), Mg exhibits five-coordination, whereas in type II solvents (THF, pyridine), Mg exhibits six-coordination. Hydration processes are quite dependent on solvent nature. In nonpolar or low-polarity solvents such as cyclohexane or chloroform, hydration is always exothermic and exergonic, despite a large entropy term that strongly opposes hydration. In polar solvents of type II, hydration is quite unfavorable, and essentially no hydrates are expected in these media, except perhaps at very large water concentrations (although, in such a case, the medium cannot be simply described as an organic solvent). In polar solvents of type I, the situation is intermediate, and dihydration is favorable in some cases (acetone, acetonitrile) and unfavorable in others (DMSO). It is interesting to note that first hydration processes in coordinating solvents (of either type I or type II), where a water molecule

  5. HPLC Analysis of Chlorophyll a, Chlorophyll b, and Beta-Carotene in Collard Greens: A Project for a Problem-Oriented Laboratory Course.

    ERIC Educational Resources Information Center

    Silveira, Augustine, Jr.; And Others

    1984-01-01

    High performance liquid chromatography (HPLC) is used to separate and quantitate beta-carotene, chlorophyll a, and chlorophyll b originating from collard greens. Experimental procedures used and typical results obtained are discussed. (JN)

  6. Analysis of the impact of cyclones on Chlorophyll-a in North Indian Ocean; a remote sensing approach

    NASA Astrophysics Data System (ADS)

    Rao Neerukattu, Srinivasa; H, Rao K.; v, Ramana I.; v, Rao M.; v, Murali Krishna I.; Anjanwyulu, A.

    Bay of Bengal (BOB) is considered to be less productive than the Arabian Sea (AS). Earlier studies attributed the reason to be strong stratified layer, which is not broken normally, for its less productivity. Monsoon winds with less wind speed are unable to break the stratified layer. Hypothetically, had there not been stratified layer in BOB, its productivity would have been comparable to that of AS. To meet the requirement of breaking stratified layer higher wind speeds are required, which are produced during cyclones. Thus the seasonal productivity comparisons has been done during cyclones, cyclones are quite common in different seasons in both BOB and AS. Four seasons of monsoon that North Indian Ocean (NIO) experience are; Spring intermonsoon (Apr - May), Southwest monsoon (June - Sep), Fall intermonsoon (Oct - Nov) and Northeast monsoon (Dec - Mar). Fourteen cyclones have been observed covering all the four seasons during for the years 1998 - 2006. During the southwest and fall seasons, cyclones occurred in either BOB or In AS and thus the comparison could not be done. Thus BOB and AS productivity during cyclones has been performed independently with out comparison between them. During the spring intermonsoon four cyclones, two in BOB (two in AS) have been observed. Four parameters of SST drop, MLD deepening, raise the percent of chlorophyll-a and increase in NPP have been derived. The parameters estimated in BOB (AS) during the cyclones are: SST drop of 5o C to 6.5o C (6.5o C to 8.5o C), MLD deepening of 30m to 90m (30m to 120m), raise in chlorophyll-a by 220 During northeast monsoon seven cyclones, four in BOB (three in AS) have been observed. In BOB, out of four cyclones, two were observed in north and two in south, where as in AS one in north and two in south were observed. Comparison was made based on latitude considering availability of sun light to be the same. The parameters estimated in northern BOB (AS) during the cyclones are: SST drop of 1.5o C to

  7. Variability in the correlation between Asian dust storms and chlorophyll a concentration from the North to Equatorial Pacific.

    PubMed

    Tan, Sai-Chun; Yao, Xiaohong; Gao, Hui-Wang; Shi, Guang-Yu; Yue, Xu

    2013-01-01

    A long-term record of Asian dust storms showed seven high-occurrence-frequency centers in China. The intrusion of Asian dust into the downwind seas, including the China seas, the Sea of Japan, the subarctic North Pacific, the North Pacific subtropical gyre, and the western and eastern Equatorial Pacific, has been shown to add nutrients to ocean ecosystems and enhance their biological activities. To explore the relationship between the transported dust from various sources to the six seas and oceanic biological activities with different nutrient conditions, the correlation between monthly chlorophyll a concentration in each sea and monthly dust storm occurrence frequencies reaching the sea during 1997-2007 was examined in this study. No correlations were observed between dust and chlorophyll a concentration in the <50 m China seas because atmospheric deposition is commonly believed to exert less impact on coastal seas. Significant correlations existed between dust sources and many sea areas, suggesting a link between dust and chlorophyll a concentration in those seas. However, the correlation coefficients were highly variable. In general, the correlation coefficients (0.54-0.63) for the Sea of Japan were highest, except for that between the subarctic Pacific and the Taklimakan Desert, where it was as high as 0.7. For the >50 m China seas and the North Pacific subtropical gyre, the correlation coefficients were in the range 0.32-0.57. The correlation coefficients for the western and eastern Equatorial Pacific were relatively low (<0.36). These correlation coefficients were further interpreted in terms of the geographical distributions of dust sources, the transport pathways, the dust deposition, the nutrient conditions of oceans, and the probability of dust storms reaching the seas. PMID:23460892

  8. Multivariate approach for chlorophyll-a and suspended matter retrievals in Case II waters using hyperspectral data

    NASA Astrophysics Data System (ADS)

    Ali, K.; Ortiz, J. D.

    2013-12-01

    Remote sensing has become very promising in providing temporal and spatial information regarding biogeodynamics in large and open freshwater bodies. However, in optically complex environments, such as in the Western Basin of Lake Erie (WBLE), the water contains multiple biogeochemical constituents or color producing agents (CPAs) such as, phytoplankton, suspend matter, and dissolved organic carbon. Identifying and analyzing in-water constituents in these waters is crucial for understanding and assessing many biogeochemical processes. For example, concentrations of chlorophyll-a and total suspended matter can be used as proxies to assess phytoplankton dynamics and particulate loading. However, quantitatively estimating concentrations of in-water constituents from satellite observations is complicated when working with mixed spectral signatures. With the advent of hyperspectral sensors, hyperspectral remote sensing is fast emerging as a key technology for advanced and improved understanding of optically complex waters. This study focuses on estimating concentration of chlorophyll-a and Total Suspended Matter (TSM) in the WBLE by applying partial least square (PLS) method to a full range (400 - 900 nm) of continuous narrow spectral bands. PLS models the covariance between hyperspectral bands and the CPAs and identifies the optimal bands that characterize most of the variance that exists in the CPAs. This method avoids the curse of dimensionality and the effects of multi-collinearity, a challenge that is associated with new generation hyperspectral satellite sensors. Validation parameters for the PLS - based models produced R2 of 0.84 for Chlorophyll-a with RMSE of 1.18μg/l, and R2 of 0.90 for TSM with RMSE = 1.26mg/l. This illustrates the potential of the PLS in isolating and extracting absorption features characterizing the various CPAs in optically complex Case II type waters.

  9. Satellite Monitoring of Chlorophyll-a Concentration in the Water Bodies of the Dnieper and Don River Basins

    NASA Astrophysics Data System (ADS)

    Moses, W. J.; Berdnikov, S.; Gitelson, A. A.

    2008-12-01

    We present and discuss here the results of our work using satellite data to estimate chlorophyll-a concentration 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 two-folded - (i) to test the potential of remote sensing as a tool for near-real-time monitoring of these water bodies, and (ii) to feed the results of our work into a larger project that involved the use of satellite technology to investigate and understand the effects on the bio-optical characteristics of these water bodies due to changes in the land use and land cover in the surrounding regions. MODIS and MERIS images were used. We tested the performance of a three-band model and a two- band model that use the reflectance at the red and NIR spectral bands for the retrieval of chlorophyll-a concentration. The higher spatial resolution and the availability of a spectral band at around 708 nm with the MERIS data offered great promise for the three-band model. We tested the applicability of two standard MODIS and MERIS algorithms for Case II waters. We compared results from several different atmospheric correction procedures available for MODIS and MERIS data. No one particular procedure was consistently and systematically better than the rest. Nevertheless, even in the absence of a perfect atmospheric correction procedure, both the three-band and the two-band models showed promising results when compared to in-situ chlorophyll-a measurements. The challenges and limitations involved in satellite remote monitoring of turbid productive waters are discussed.

  10. Variability in the Correlation between Asian Dust Storms and Chlorophyll a Concentration from the North to Equatorial Pacific

    PubMed Central

    Tan, Sai-Chun; Yao, Xiaohong; Gao, Hui-Wang; Shi, Guang-Yu; Yue, Xu

    2013-01-01

    A long-term record of Asian dust storms showed seven high-occurrence-frequency centers in China. The intrusion of Asian dust into the downwind seas, including the China seas, the Sea of Japan, the subarctic North Pacific, the North Pacific subtropical gyre, and the western and eastern Equatorial Pacific, has been shown to add nutrients to ocean ecosystems and enhance their biological activities. To explore the relationship between the transported dust from various sources to the six seas and oceanic biological activities with different nutrient conditions, the correlation between monthly chlorophyll a concentration in each sea and monthly dust storm occurrence frequencies reaching the sea during 1997–2007 was examined in this study. No correlations were observed between dust and chlorophyll a concentration in the <50 m China seas because atmospheric deposition is commonly believed to exert less impact on coastal seas. Significant correlations existed between dust sources and many sea areas, suggesting a link between dust and chlorophyll a concentration in those seas. However, the correlation coefficients were highly variable. In general, the correlation coefficients (0.54–0.63) for the Sea of Japan were highest, except for that between the subarctic Pacific and the Taklimakan Desert, where it was as high as 0.7. For the >50 m China seas and the North Pacific subtropical gyre, the correlation coefficients were in the range 0.32–0.57. The correlation coefficients for the western and eastern Equatorial Pacific were relatively low (<0.36). These correlation coefficients were further interpreted in terms of the geographical distributions of dust sources, the transport pathways, the dust deposition, the nutrient conditions of oceans, and the probability of dust storms reaching the seas. PMID:23460892

  11. Femtosecond Nonlinear Optical Studies of Radiationless Decay in Carotenoids and in the Peridinin-Chlorophyll a Protein

    NASA Astrophysics Data System (ADS)

    Ghosh, Soumen; Bishop, Michael; Mueller, Jenny Jo; Shepherd, Nolan; Beck, Warren; Frank, Harry

    2014-03-01

    Femtosecond transient-grating spectroscopy with optical heterodyne detection was employed to observe the time evolution of the absorption and dispersion components of the third-order nonlinear optical signal following resonant excitation of the S2 (1Bu+)states of βcarotene in benzonitrile and peridinin in methanol. The absorption and dispersion components exhibit distinct time profiles owing to the population of dark intermediate states. An initial intermediate is populated on an ultrashort (<30 fs) time scale in both carotenoids owing to the onset of torsional distortions on the S2-state potential surface. The time-resolved transient-grating spectra obtained for peridinin in the peridinin-chlorophyll a protein from Amphidinium carterae indicate that the intermediate is formed even more rapidly than in solution. This finding suggests that the twisted conformation of the peridinin chromophore is controlled in the binding site so as to optimize energy transfer to chlorophyll a by enhancing the formation of an intramolecular charge-transfer character. Supported by the Department of Energy, BES Photosynthetic Systems Program, under Award Number DE-SC0010847.

  12. Characterization of photosystem 1 chlorophyll a/b-binding apoprotein accumulation in developing soybean using type-specific antibodies

    NASA Technical Reports Server (NTRS)

    Henry, R. L.; Armbrust, T.; Gallegos, G.; Guikema, J. A.; Spooner, B. S. (Principal Investigator)

    1992-01-01

    The structure and supramolecular assembly of the soybean photosystem 1 (PS 1) chlorophyll a/b-binding antenna (LHC 1) was examined. We identified the subunit composition of LHC 1 in soybean and followed the accumulation of individual subunits during light-induced assembly. We observed four LHC 1 subunits, at 23, 22, 21 and 20.5 kDa, obtained partial sequence information by amino-terminal sequence analysis, and classified the 20.5, 22, and 21 kDa subunits as being encoded by type I, II, and IV chlorophyll a/b binding protein genes, respectively. Antisera against LHC 1 subunits were used to follow the accumulation of individual subunits during the light-initiated transition from etioplast to chloroplast. Several points are noteworthy. First, monospecific antibody against the 22 kDa subunit decorated a 25 kDa peptide in etiolated tissue, which declined during maturation. This decline correlated with the light-induced appearance of mature 22 kDa peptide, suggesting a precursor/product relationship. Second, the same antibody identified a 22 kDa protein in mature corn, but not a larger band in etiolated corn, suggesting that LHC 1 accumulation is regulated differently between species before the onset of chlorophyll biosynthesis. Third, the mature 22 kDa subunit appeared somewhat later than the other LHC 1 peptides during greening, implying that this subunit is less intimately associated with the PS1 core than are the subunits appearing earlier in development.

  13. Comparison of Chlorophyll-A Algorithms for the Transition Zone Between the North Sea and Baltic Sea

    NASA Astrophysics Data System (ADS)

    Huber, Silvia; Hansen, Lars B.; Rasmussen, Mads O.; Kaas, Hanne

    2015-12-01

    Monitoring water quality of the transition zone between the North Sea and Baltic Sea from space is still a challenge because of the optically complex waters. The presence of suspended sediments and dissolved substances often interfere with the phytoplankton signal and thus confound conventional case-1 algorithms developed for the open ocean. Specific calibration to case-2 waters may compensate for this. In this study we compared chlorophyll-a (chl-a) concentrations derived with three different case-2 algorithms: C2R, FUB/WeW and CoastColour using MERIS data as basis. Default C2R and FUB clearly underestimate higher chl-a concentrations. However, with local tuning we could significantly improve the fit with in-situ data. For instance, the root mean square error is reduced by roughly 50% from 3.06 to 1.6 μ g/L for the calibrated C2R processor as compared to the default C2R. This study is part of the FP7 project AQUA-USERS which has the overall goal to provide the aquaculture industry with timely information based on satellite data and optical in-situ measurements. One of the products is chlorophyll-a concentration.

  14. Development of empirical potential functions for the study of molecular geometry, and applications to chlorophyll a dimers

    SciTech Connect

    Oie, Tetsuro

    1980-07-28

    A purpose of the present studies is twofold: (1) development of an empirical potential function (EDF) and (2) application of it to the studies of photoreaction center chlorophyll a dimer. The reliable estimate of geometric structures and energies of large molecules by quantum mechanical methods is not possible at the present time. An alternative method is, therefore, needed for the studies of large molecular systems, and Chapter I is dedicated to the development of this tool, i.e., an empirical potential function, which could suffice this purpose. Because of a large number of variable chemical compositions and functional groups characteristically present in a large molecule, it is important to include a large number of structurally diverse molecules in the development of the EPF. In Chapter II, the EPF is applied to study the geometrical structure of a chlorophyll a (Ch1 a) dimer, which is believed to exist at the photoreaction center of green plants and is known to play an essential role in photosynthetic energy conversion. Although various models have been proposed for this dimer structure, there is still a great need for information concerning the detailed geometric structure of this dimer. Therefore, in this chapter the structural stabilities of various dimer models are examined by the EPF, and detailed and quantitative information on the structure and stability of these models is provided.

  15. Development of empirical potential functions for the study of molecular geometry, and applications to chlorophyll a dimers. [Dissertation

    SciTech Connect

    Oie, Tetsuro

    1980-01-01

    A purpose of the present studies is twofold: (1) development of an empirical potential function (EPF) and (2) application of it to the studies of photoreaction center chlorophyll a dimer. The reliable estimate of geometric structures and energies of large molecules by quantum mechanical methods is not possible at the present time. An alternative method is, therefore, needed for the studies of large molecular systems, and Chapter I is dedicated to the development of this tool, i.e., an empirical potential function, which could suffice this purpose. Because of a large number of variable chemical compositions and functional groups characteristically present in a large molecule, it is important to include a large number of structurally diverse molecules in the development of the EPF. In Chapter II, the EPF is applied to study the geometrical structure of a chlorophyll a (Chl a) dimer, which is believed to exist at the photoreaction center of green plants and is known to play an essential role in photosynthetic energy conversion. Although various models have been proposed for this dimer structure, there is still a great need for information concerning the detailed geometric structure of this dimer. Therefore, in this chapter the structural stabilities of various dimer models are examined by the EPF, and detailed and quantitative information on the structure and stability of these models is provided.

  16. Effects of sodium chloride on the properties of chlorophyll a submonolayer adsorbed onto hydrophobic and hydrophilic surfaces using broadband spectroscopy with single-mode integrated optical waveguides

    NASA Astrophysics Data System (ADS)

    Wiederkehr, Rodrigo S.; Hoops, Geoffrey C.; Mendes, Sergio B.

    2011-07-01

    In this work, we experimentally investigated the effects of sodium chloride on the molar absorptivity and surface density of a submonolayer of chlorophyll a adsorbed onto hydrophilic and hydrophobic solid/liquid interfaces. Those investigations were made possible by a broadband spectroscopic platform based on single-mode, integrated optical waveguides, which allows for extremely sensitive spectroscopic detection of analytes immobilized at submonolayer levels. Chlorophyll a with a constant bulk concentration (1.4 μM) was dissolved in phosphate buffer solutions (7 mM) of neutral pH, but with different sodium chloride concentrations. For a buffer solution of 1 mM of sodium chloride, the measured surface density of chlorophyll a was 0.209 pmol/cm2 for a hydrophilic and 0.125 pmol/cm2 for a hydrophobic surface. For a phosphate buffer solution of 10 mM of sodium chloride, the measured surface density of chlorophyll a was 0.528 pmol/cm2 for a hydrophilic and 0.337 pmol/cm2 for a hydrophobic surface. Additionally, a hypsochromic shift of the Soret band was observed for the adsorbed pigment in correlation with an increase in buffer ionic strength. The adsorption of chlorophyll a onto different surfaces can play an important role to elucidate several processes found in nature and provide a rationale for bio-inspired new material technologies.

  17. The potential impact of an inter-basin water transfer project on nutrients (nitrogen and phosphorous) and chlorophyll a of the receiving water system.

    PubMed

    Zeng, Qinghui; Qin, Lihuan; Li, Xuyong

    2015-12-01

    Any inter-basin water transfer project would cause complex physical, chemical, hydrological and biological changes to the receiving system. The primary channel of the middle route of the South-to-North Water Transfer Project has a total length of 1267 km. There is a significant difference between the physical, chemical and biological characteristics of the originating and receiving drinking water conservation districts. To predict the impacts of this long-distance inter-basin water transfer project on the N&P (nitrogen and phosphorus) concentrations and eutrophication risk of the receiving system, an environmental fluid dynamics code (EFDC) model was applied. The calibrated model accurately reproduced the hydrodynamic, water quality and the entire algal bloom process. Thirteen scenarios were defined to fully understand the N&P and chlorophyll a (Chl a) variation among different hydrological years, different quantity and timing of water transfer, and different inflows of N&P concentrations. The results showed the following: (a) The water transfer project would not result in a substantial difference to the trophic state of the Miyun reservoir in any of the hydrological years. (b) The area affected by the water transfer did not involve the entire reservoir. To minimize the impact of water transfer on N&P nutrients and Chl a, water should be transferred as uniform as possible with small discharge. (c) The variation in Chl a was more sensitive to an increase in P than an increase in N for the transferred water. The increased percentages of the average Chl a concentration when water was transferred in the spring, summer and autumn were 7.76%, 16.67% and 16.45%. Our findings imply that special attention should be given to prevent P increment of the transferred water from May to October to prevent algal blooms. The results provide useful information for decision makers about the quantity and timing of water transfers. PMID:26247693

  18. The Chlorophyll a Fluorescence Modulated by All-Trans-β-Carotene in the Process of Photosystem II

    PubMed Central

    Li, Tianyu; Zhang, Ye; Gong, Nan; Li, Zuowei; Sun, Chenglin; Men, Zhiwei

    2016-01-01

    Modulating the chlorophyll a (Chl-a) fluorescence by all-trans-β-Carotene (β-Car) in the polarity and non-polarity solutions was investigated. The fluorescence intensity of Chl-a decreased as the concentration of β-Car increased. The excited electronic levels of Chl-a and β-Car became much closer owing to the solvent effect, which led to the electron transfer between both two molecules. A electron-separated pair Chl−·Chl+ that is not luminous was formed due to electron transfer. The solution of Chl-a and β-car in C3H6O was similar to the internal environment of chloroplast. We conclude that the polar solvent is good for the fluorescent modulation in photosystem II. PMID:27338363

  19. Chlorophyll a in suspended particulate matter of the Caspian Sea as an indicator of biogenic sedimentation conditions

    NASA Astrophysics Data System (ADS)

    Kravchishina, M. D.; Klyuvitkin, A. A.; Pautova, L. A.; Politova, N. V.; Lein, A. Yu.; Lisitzin, A. P.

    2015-11-01

    The conditions of biogenic sedimentation (concentration of chlorophyll a (chl a), particulate organic carbon (POC), and its isotope composition (δ13CPOC)), as well as the quantitative characteristics of phytoplankton, and the total concentration of suspended particulate matter have been studied in the Caspian Sea in May and June 2012. The vertical (from the surface layer to bottom) distribution and precipitation of the biogenic component of suspended particulate matter have been determined. It was found that only 5% of the particulate matter and around 3% of POC reached the Middle Caspian after passing through a marginal filter (Volga River delta-Northern Caspian). The subsurface chl a maximum layer (around 20-60 m) with a cold-water phytoplankton community was revealed in the Middle and Southern Caspian. The subsurface region of accumulation of chl a and phytoplankton in the subthermocline layer has been extended from the southern periphery of the Derbent Depression to the Absheron Sill.

  20. Diffuse reflectance of the ocean - The theory of its augmentation by chlorophyll a fluorescence at 685 nm

    NASA Technical Reports Server (NTRS)

    Gordon, H. R.

    1979-01-01

    The radiative transfer equation is modified to include the effect of fluorescent substances and solved in the quasi-single scattering approximation for a homogeneous ocean containing fluorescent particles with wavelength independent quantum efficiency and a Gaussian shaped emission line. The results are applied to the in vivo fluorescence of chlorophyll a (in phytoplankton) in the ocean to determine if the observed quantum efficiencies are large enough to explain the enhancement of the ocean's diffuse reflectance near 685 nm in chlorophyll rich waters without resorting to anomalous dispersion. The computations indicate that the required efficiencies are sufficiently low to account completely for the enhanced reflectance. The validity of the theory is further demonstrated by deriving values for the upwelling irradiance attenuation coefficient at 685 nm which are in close agreement with the observations.

  1. Theoretical investigation of fluorescence concentration quenching in two-dimensional disordered systems. Application to chlorophyll a in monolayers of dioleylphosphatidylcholine

    SciTech Connect

    Boulu, L.G.; Patterson, L.K.; Chauvet, J.P.; Kozak, J.J.

    1987-01-15

    A master equation approach is used for investigating energy transfer and trapping in two-dimensional disordered systems, where the traps are statistical pairs of pigment molecules closer than a critical distance R/sub c/. Fluorescence decay curves are calculated over a range of concentrations as a function of R/sub c/ and the Foerster transfer radius R-bar/sub 0/. The concentration dependence of the lifetimes is compared to the fluorescence self-quenching data that Chauvet et al. obtained from real-time measurements in monolayers of chlorophyll a and dioleylphosphatidylcholine (DOL). This dependence is found to be close to second order and for a choice of R/sub c/ = 10 A the experimental data are fit if R-bar/sub 0/ = 78 +- 2 A. This value is in close agreement with those found in the literature from depolarization measurements.

  2. LETTERS TO THE EDITOR: Emission of fluorescence from chlorophyll a in vivo due to nanosecond pulsed laser excitation

    NASA Astrophysics Data System (ADS)

    Bunin, D. K.; Gorbunov, M. Yu; Fadeev, V. V.; Chekalyuk, A. M.

    1992-05-01

    A model was proposed and tested experimentally to describe the emission of fluorescence by chlorophyll a in vivo as a result of pulsed laser excitation. This model takes into account the migration of excitons between various photosynthetic units, singlet-singlet annihilation of excitons, pigment bleaching, and also the influence of various states of the photosystem II reaction centers. A method was developed to measure the average number of excitons reaching a photosystem II reaction center during a pulse. This involved two-pulse laser excitation. It was found that the rates of exciton capture by the reaction centers were the same for the PIQ and P +IQ - states of the photosystem II reaction centers, whereas the rate of exciton capture in the P +I -Q - state was half that for the PIQ - state.

  3. In Vivo and in Vitro Chlorophyll-a and Pheophytin-a Concentration Measurements by Laser Fluorometry

    NASA Technical Reports Server (NTRS)

    Demidov, A. A.; Baulin, E. V.; Chernyavskaya, E. A.

    1992-01-01

    Discussed here is the application of a laser fluorescent technique in in vivo and in vitro phyto- and zooplankton analysis involving popular lasers, an impulse YAG laser (lambda = 532 nm) and a steady state He-Cd (lambda = 440 nm). The YAG laser is widely used in laser remote sensing of seawater photoplankton in situ mode, but here we give special attention to its use in the precise estimation of phytoplankton pigments using laser induced fluorescence. The He-Cd laser is a novice in this field and, we believe, very promising. Our methods enable one to detect, in viro, chlorophyll-a (Chl-a) concentration in the water probe up to 10 nanograms per liter, and to measure, in vitro, Chl-a and pheophytin-a (Ph-a) concentrations in acetone extracts of phyto- and zooplankton up to 1 nanogram per liter.

  4. The Chlorophyll a Fluorescence Modulated by All-Trans-β-Carotene in the Process of Photosystem II.

    PubMed

    Li, Tianyu; Zhang, Ye; Gong, Nan; Li, Zuowei; Sun, Chenglin; Men, Zhiwei

    2016-01-01

    Modulating the chlorophyll a (Chl-a) fluorescence by all-trans-β-Carotene (β-Car) in the polarity and non-polarity solutions was investigated. The fluorescence intensity of Chl-a decreased as the concentration of β-Car increased. The excited electronic levels of Chl-a and β-Car became much closer owing to the solvent effect, which led to the electron transfer between both two molecules. A electron-separated pair Chl(-)·Chl⁺ that is not luminous was formed due to electron transfer. The solution of Chl-a and β-car in C₃H₆O was similar to the internal environment of chloroplast. We conclude that the polar solvent is good for the fluorescent modulation in photosystem II. PMID:27338363

  5. Moving toward finer scales in oceanography: Predictive linear functional model of Chlorophyll a profile from light data

    NASA Astrophysics Data System (ADS)

    Bayle, Séverine; Monestiez, Pascal; Guinet, Christophe; Nerini, David

    2015-05-01

    The Southern Ocean plays a key role in ocean-atmosphere carbon dioxide fluxes. Estimation of carbon exchanges between ocean and atmosphere must rely on accurate estimations of primary productivity which require measurements of phytoplankton concentration within the water column. In this paper, we are interested in relationships between primary productivity and light in the Antarctic ocean. The originality of this work is twofold. Starting from physical hypothesis, a statistical model is constructed for the prediction of Chlorophyll a (Chl a) profiles where light profiles are used as a covariate. Taking into account of the functional nature of the data, solutions are proposed to estimate continuous vertical profiles from discrete data sampled by elephant seals equipped with a new generation of oceanographic tags. Bootstrapped prediction intervals show a good quality of prediction of Chl a profiles, giving access to the shape of the profiles along depth and to the submesoscale structure of phytoplankton within the euphotic layer of the Southern Ocean.

  6. Vibrational relaxation as the driving force for wavelength conversion in the peridinin-chlorophyll a-protein.

    PubMed

    Götze, Jan P; Karasulu, Bora; Patil, Mahendra; Thiel, Walter

    2015-12-01

    We present a computationally derived energy transfer model for the peridinin-chlorophyll a-protein (PCP), which invokes vibrational relaxation in the two lowest singlet excited states rather than internal conversion between them. The model allows an understanding of the photoinduced processes without assuming further electronic states or a dependence of the 2Ag state character on the vibrational sub-state. We report molecular dynamics simulations (CHARMM22 force field) and quantum mechanics/molecular mechanics (QM/MM) calculations on PCP. In the latter, the QM region containing a single peridinin (Per) chromophore or a Per-Chl a (chlorophyll a) pair is treated by density functional theory (DFT, CAM-B3LYP) for geometries and by DFT-based multireference configuration interaction (DFT/MRCI) for excitation energies. The calculations show that Per has a bright, green light absorbing 2Ag state, in addition to the blue light absorbing 1Bu state found in other carotenoids. Both states undergo a strong energy lowering upon relaxation, leading to emission in the red, while absorbing in the blue or green. The orientation of their transition dipole moments indicates that both states are capable of excited-state energy transfer to Chl a, without preference for either 1Bu or 2Ag as donor state. We propose that the commonly postulated partial intramolecular charge transfer (ICT) character of a donating Per state can be assigned to the relaxed 1Bu state, which takes on ICT character. By assuming that both 1Bu and 2Ag are able to donate to the Chl a Q band, one can explain why different chlorophyll species in PCP exhibit different acceptor capabilities. PMID:26231454

  7. Novel decomposition products of chlorophyll- a in continental shelf (Louisiana shelf) sediments: formation and transformation of carotenol chlorin esters

    NASA Astrophysics Data System (ADS)

    Chen, Nianhong; Bianchi, Thomas S.; Bland, John M.

    2003-06-01

    In April 2000, we collected box cores from five stations along a cross-shelf transect on the Louisiana (LA) continental shelf. Novel esters of carotenols and chlorins (carotenoid chlorin esters, CCEs), which are highly specific grazing markers, were identified in surface and deep sediments (>10 cm) from the LA shelf. Chlorophyll- a inventory indicated that CCEs are one of the major decay products of chlorophyll- a in shelf sediments. Abundances of total CCEs (9-18%) in surface sediments along the cross-shelf transect were comparable to the abundance of pheophytin- a, pyropheophytin- a, and total steryl chlorin esters (SCEs). Prior work has identified four CCEs which have dehydrated fucoxanthin/fucoxanthinol as a substitute alcohol of phytol. We report on four newly identified CCEs associated with nondehydrated fuxocanthin/fucoxanthinol esterified to (pyro)pheophorbide- a. These nondehydrated CCEs were generally present in lower concentrations than their dehydrated counterparts, but were detectable by atmospheric pressure chemical ionization (APCI) mass spectrometry coupled with high-performance liquid chromatography (HPLC). We attributed differences between this study and previous work to the time allowed for predepositional decay and grazing processes to occur. The rapid sedimentation of CCEs in the shallow water column (ca. 10 m) on the LA shelf allowed for effective burial of all CCEs compared to the deeper water column regions sampled by previous work. This speculation is supported by the fact that the concentrations of CCEs with nondehydrated fucoxanthin/fucoxanthinol were extremely low in sediments from the site on the outer LA shelf with a deeper (253 m) water column. We also tentatively identified an additional CCE and its isomer as fucoxanthinol didehydrate pyropheophorbide- a ester. We suggest that the formation and transformation of CCEs are primarily controlled by the following three biologically mediated reactions: demethoxycarbonylation, dehydration

  8. Are Bryophytes Shade Plants? Photosynthetic Light Responses and Proportions of Chlorophyll a, Chlorophyll b and Total Carotenoids

    PubMed Central

    MARSCHALL, MARIANN; PROCTOR, MICHAEL C. F.

    2004-01-01

    • Background and Aims Data are presented from 39 species of mosses and 16 liverworts for ratios of chlorophylls and total carotenoids, and light saturation of photosynthetic electron flow or photosynthetic CO2 uptake, in relation to the postulate that bryophyte cells in general show shade-plant characteristics. • Methods Pigment concentrations were measured by spectrophotometer in 80 % acetone extracts. Light-saturation curves were constructed by (modulated) chlorophyll florescence and for some species by infra-red gas analysis. • Key Results The pigment measurements were widely variable but broadly in line with the findings of previous authors. Median values (mosses/liverworts) were: total chlorophyll, 1·64/3·76 mg g−1; chlorophyll a : b, 2·29/1·99; chlorophylls : carotenoids, 4·74/6·75). The PPFD values at 95 % saturation (estimated from fitted curves) also ranged widely, but were almost all <1000 µmol m−2 s−1; the median for mosses was 583 and for liverworts 214 µmol m−2 s−1. The two highest PPFD95% values were from Polytrichum species with lamella systems forming a ventilated photosynthetic tissue. Total chlorophyll, chlorophyll a : b and chlorophylls : carotenoids all correlated significantly with PPFD95%. • Conclusions Bryophytes include but are not inherently shade plants. Light-saturation levels for species of open sun-exposed habitats are lower than for vascular sun plants and are probably limited by CO2 diffusion into unistratose leaves; this limit can only be exceeded by bryophytes with ventilated photosynthetic tissues which provide increased area for CO2 uptake. PMID:15319230

  9. Evaluation of chlorophyll-a retrieval algorithms based on MERIS bands for optically varying eutrophic inland lakes.

    PubMed

    Lyu, Heng; Li, Xiaojun; Wang, Yannan; Jin, Qi; Cao, Kai; Wang, Qiao; Li, Yunmei

    2015-10-15

    Fourteen field campaigns were conducted in five inland lakes during different seasons between 2006 and 2013, and a total of 398 water samples with varying optical characteristics were collected. The characteristics were analyzed based on remote sensing reflectance, and an automatic cluster two-step method was applied for water classification. The inland waters could be clustered into three types, which we labeled water types I, II and III. From water types I to III, the effect of the phytoplankton on the optical characteristics gradually decreased. Four chlorophyll-a retrieval algorithms for Case II water, a two-band, three-band, four-band and SCI (Synthetic Chlorophyll Index) algorithm were evaluated for three water types based on the MERIS bands. Different MERIS bands were used for the three water types in each of the four algorithms. The four algorithms had different levels of retrieval accuracy for each water type, and no single algorithm could be successfully applied to all water types. For water types I and III, the three-band algorithm performed the best, while the four-band algorithm had the highest retrieval accuracy for water type II. However, the three-band algorithm is preferable to the two-band algorithm for turbid eutrophic inland waters. The SCI algorithm is recommended for highly turbid water with a higher concentration of total suspended solids. Our research indicates that the chlorophyll-a concentration retrieval by remote sensing for optically contrasted inland water requires a specific algorithm that is based on the optical characteristics of inland water bodies to obtain higher estimation accuracy. PMID:26057542

  10. Extraction of ozone and chlorophyll-A distribution from AVIRIS data

    NASA Technical Reports Server (NTRS)

    Schaepman, M.; Itten, K. I.; Schlaepfer, D.; Kurer, U.; Veraguth, S.; Keller, J.

    1995-01-01

    The potential of airborne imaging spectrometry for assessing and monitoring natural resources is studied. Therefore, an AVIRIS scene of the NASA's MacEurope 1991 campaign - acquired in Central Switzerland - is used. The test site consists of an urban area, the Lake Zug with its surrounding fields, the Rigi mountain in the center of the test site, and the Lake of Four Cantons. The region is covered by the AVIRIS flight #910705, run 6 and 7 of the NASA ER-2 aircraft resulting in an average nominal pixel size of about 18 m. Simultaneous to the ER-2 overflight spectroradiometric measurements have been taken in various locations. Preselected reference targets were measured in the field with a GER Mark V spectroradiometer, and radiance measurements were taken to the lake using a Li-Cor LI 1800UW specroradiometer below and above the water surface. A comprehensive meteorological data set was obtained by joining the POLLUMET experiment which carried out measurements to investigate the summer smog in Switzerland on the same day. The quality assessment for the actual data set can be found in detail in Meyer et al. A parametric approach calculating the location of the airplane was used to simulate the observation geometry. This parametric preprocessing procedure, which takes care of effects of flight line and attitude variations as well as the pixel-by-pixel topographic corrections is described in Meyer.

  11. Near infrared-red models for the remote estimation of chlorophyll- a concentration in optically complex turbid productive waters: From in situ measurements to aerial imagery

    NASA Astrophysics Data System (ADS)

    Gurlin, Daniela

    Today the water quality of many inland and coastal waters is compromised by cultural eutrophication in consequence of increased human agricultural and industrial activities and remote sensing is widely applied to monitor the trophic state of these waters. This study explores near infrared-red models for the remote estimation of chlorophyll-a concentration in turbid productive waters and compares several near infrared-red models developed within the last 35 years. Three of these near infrared-red models were calibrated for a dataset with chlorophyll-a concentrations from 2.3 to 81.2 mg m -3 and validated for independent and statistically significantly different datasets with chlorophyll-a concentrations from 4.0 to 95.5 mg m-3 and 4.0 to 24.2 mg m-3 for the spectral bands of the MEdium Resolution Imaging Spectrometer (MERIS) and Moderate-resolution Imaging Spectroradiometer (MODIS). The developed MERIS two-band algorithm estimated chlorophyll-a concentrations from 4.0 to 24.2 mg m-3, which are typical for many inland and coastal waters, very accurately with a mean absolute error 1.2 mg m-3. These results indicate a high potential of the simple MERIS two-band algorithm for the reliable estimation of chlorophyll-a concentration without any reduction in accuracy compared to more complex algorithms, even though more research seems required to analyze the sensitivity of this algorithm to differences in the chlorophyll-a specific absorption coefficient of phytoplankton. Three near infrared-red models were calibrated and validated for a smaller dataset of atmospherically corrected multi-temporal aerial imagery collected by the hyperspectral airborne imaging spectrometer for applications (AisaEAGLE). The developed algorithms successfully captured the spatial and temporal variability of the chlorophyll-a concentrations and estimated chlorophyll- a concentrations from 2.3 to 81.2 mg m-3 with mean absolute errors from 4.4 mg m-3 for the AISA two band algorithm to 5.2 mg m-3

  12. Chlorophyll-a concentration estimation with three bio-optical algorithms: correction for the low concentration range for the Yiam Reservoir, Korea

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bio-optical algorithms have been applied to monitor water quality in surface water systems. Empirical algorithms, such as Ritchie (2008), Gons (2008), and Gilerson (2010), have been applied to estimate the chlorophyll-a (chl-a) concentrations. However, the performance of each algorithm severely degr...

  13. CHANGES IN CHLOROPHYLL A FLOURESCENCE AND PIGMENT RATIOS DURING DIFFERENT GROWTH PHASES OF A UNICELLULAR MARINE CHAETOCEROS (BACILLAROPHYCEAE) IN BATCH CULTURE

    EPA Science Inventory

    Interpretations of chlorophyll a fluorescence data are based largely on application with green algae and higher plants. This study evaluated the interpretation of fluorescence data for a unicellular marine diatom. Chaetoceros sp. was grown in 4-liter batch cultures on a 16:8, L:D...

  14. Satellite remote sensing of chlorophyll a in support of nutrient management in the Neuse and Tar-Pamlico River (North Carolina) estuaries

    EPA Science Inventory

    The North Carolina Environmental Management Commission (EMC) has adopted as a water quality standard that chlorophyll a concentration should not exceed 40 ug/L in sounds, estuaries and other slow-moving waters. Exceedances require regulators to develop a Total Maximum Daily Limit...

  15. Separate introns gained within short and long soluble peridinin-chlorophyll a-protein genes during radiation of Symbiodinium (Dinophyceae) clade A and B lineages

    EPA Science Inventory

    Peridinin-containing dinoflagellates express short (15-17 kD) and/or long (32-35kD) soluble peridinin-chlorophyll a-proteins (sPCP) that harvest blue-green light within chloroplast thylacoid lumens. The previously described pseudo-axis of symmetry in long sPCPs and phylogenetic e...

  16. Normal-Phase Open Column versus Reversed-Phase High Performance Liquid Chromatography: Separation of Chlorophyll a and Chlorophyll b from their Diastereomers.

    ERIC Educational Resources Information Center

    Schaber, Peter M.

    1985-01-01

    Background information, procedures used, and typical results obtained are provided for an experiment involving the separation of chlorophyll a and chlorophyll b from their diastereomers. Reasons why the experiment can be easily integrated into most laboratory curricula where high-performance liquid chromatography capabilities exist are given. (JN)

  17. The relative influence of local and regional environmental drivers of algal biomass (chlorophyll-a) varies by estuarine location

    NASA Astrophysics Data System (ADS)

    Wainger, Lisa; Yu, Hao; Gazenski, Kim; Boynton, Walter

    2016-09-01

    A major question in restoring estuarine water quality is whether local actions to manage excess nutrients can be effective, given that estuaries are also responding to tidal inputs from adjacent water bodies. Several types of statistical analysis were used to examine spatially-detailed and long-term water quality monitoring data in eight sub-estuaries of Chesapeake Bay. These sub-estuaries are likely to be similar to other shallow systems with moderate to long water residence times. Statistical cluster analysis of spatial water quality data suggested that estuaries had spatially distinct water quality zones and that the peak algal biomass (as measured by chlorophyll-a) was most often controlled by local watershed inputs in all but one estuary, although mainstem inputs affected most estuaries at some times and places. An elasticity indicator that compared inter-annual changes in sub-estuaries to parallel changes in the mainstem Chesapeake Bay supported the idea that water quality in sub-estuaries was not strongly coupled to the mainstem. A cross-channel zonation of water quality observed near the mouth of estuaries suggested that Bay influences were stronger on the right side of the lower channel (looking up estuary) at times in all estuaries, and was most common in small estuaries closest to the mouth of the primary water source to the estuary. Where Bay influences were strong, estuarine water quality would be expected to be less responsive to nutrient reductions made in the local watershed. Regression analysis was used to evaluate hypothesized relationships between environmental driver variables and average chlorophyll-a (chl-a) concentrations. Chl-a values were calculated from unusually detailed levels of spatial sampling, potentially providing a more comprehensive view of system conditions than that provided by traditional sparse sampling networks. The univariate models with the best data support to explain variability in averaged chl-a concentration were those

  18. Defining Mediterranean and Black Sea Biogeochemical Subprovinces and Synthetic Ocean Indicators Using Mesoscale Oceanographic Features

    PubMed Central

    Nieblas, Anne-Elise; Drushka, Kyla; Reygondeau, Gabriel; Rossi, Vincent; Demarcq, Hervé; Dubroca, Laurent; Bonhommeau, Sylvain

    2014-01-01

    The Mediterranean and Black Seas are semi-enclosed basins characterized by high environmental variability and growing anthropogenic pressure. This has led to an increasing need for a bioregionalization of the oceanic environment at local and regional scales that can be used for managerial applications as a geographical reference. We aim to identify biogeochemical subprovinces within this domain, and develop synthetic indices of the key oceanographic dynamics of each subprovince to quantify baselines from which to assess variability and change. To do this, we compile a data set of 101 months (2002–2010) of a variety of both “classical” (i.e., sea surface temperature, surface chlorophyll-a, and bathymetry) and “mesoscale” (i.e., eddy kinetic energy, finite-size Lyapunov exponents, and surface frontal gradients) ocean features that we use to characterize the surface ocean variability. We employ a k-means clustering algorithm to objectively define biogeochemical subprovinces based on classical features, and, for the first time, on mesoscale features, and on a combination of both classical and mesoscale features. Principal components analysis is then performed on the oceanographic variables to define integrative indices to monitor the environmental changes within each resultant subprovince at monthly resolutions. Using both the classical and mesoscale features, we find five biogeochemical subprovinces for the Mediterranean and Black Seas. Interestingly, the use of mesoscale variables contributes highly in the delineation of the open ocean. The first axis of the principal component analysis is explained primarily by classical ocean features and the second axis is explained by mesoscale features. Biogeochemical subprovinces identified by the present study can be useful within the European management framework as an objective geographical framework of the Mediterranean and Black Seas, and the synthetic ocean indicators developed here can be used to monitor

  19. Defining Mediterranean and Black Sea biogeochemical subprovinces and synthetic ocean indicators using mesoscale oceanographic features.

    PubMed

    Nieblas, Anne-Elise; Drushka, Kyla; Reygondeau, Gabriel; Rossi, Vincent; Demarcq, Hervé; Dubroca, Laurent; Bonhommeau, Sylvain

    2014-01-01

    The Mediterranean and Black Seas are semi-enclosed basins characterized by high environmental variability and growing anthropogenic pressure. This has led to an increasing need for a bioregionalization of the oceanic environment at local and regional scales that can be used for managerial applications as a geographical reference. We aim to identify biogeochemical subprovinces within this domain, and develop synthetic indices of the key oceanographic dynamics of each subprovince to quantify baselines from which to assess variability and change. To do this, we compile a data set of 101 months (2002-2010) of a variety of both "classical" (i.e., sea surface temperature, surface chlorophyll-a, and bathymetry) and "mesoscale" (i.e., eddy kinetic energy, finite-size Lyapunov exponents, and surface frontal gradients) ocean features that we use to characterize the surface ocean variability. We employ a k-means clustering algorithm to objectively define biogeochemical subprovinces based on classical features, and, for the first time, on mesoscale features, and on a combination of both classical and mesoscale features. Principal components analysis is then performed on the oceanographic variables to define integrative indices to monitor the environmental changes within each resultant subprovince at monthly resolutions. Using both the classical and mesoscale features, we find five biogeochemical subprovinces for the Mediterranean and Black Seas. Interestingly, the use of mesoscale variables contributes highly in the delineation of the open ocean. The first axis of the principal component analysis is explained primarily by classical ocean features and the second axis is explained by mesoscale features. Biogeochemical subprovinces identified by the present study can be useful within the European management framework as an objective geographical framework of the Mediterranean and Black Seas, and the synthetic ocean indicators developed here can be used to monitor variability and

  20. A hybrid algorithm for estimating the chlorophyll-a concentration across different trophic states in Asian inland waters

    NASA Astrophysics Data System (ADS)

    Matsushita, Bunkei; Yang, Wei; Yu, Gongliang; Oyama, Youichi; Yoshimura, Kazuya; Fukushima, Takehiko

    2015-04-01

    The chlorophyll-a (Chl-a) concentration is one of the most important parameters for evaluating the state of water environments, which often vary markedly across both time and space. Here we propose a hybrid algorithm for retrieving the Chl-a values from in situ remote sensing data. This hybrid algorithm contains three individual Chl-a estimation algorithms that were previously developed for clear waters (a blue-green algorithm), turbid waters (a two-band index-based red-near infrared algorithm), and highly turbid waters (a three-band index-based red-near infrared algorithm). The MCI value (maximum chlorophyll index) was used to switch the three algorithms. To evaluate the performance of the proposed hybrid algorithm, we used the in situ remote sensing reflectance and Chl-a values collected from five Asian lakes, the trophic status of which varied from oligotrophic to hypertrophic. The results showed that the hybrid algorithm performed well for a wide variety of optical properties, with the NMAE (normalized mean absolute error) of 13.3%. Our results indicate that the proposed hybrid algorithm has the potential for use as an operational tool for monitoring Chl-a in waters with widely varying trophic conditions without the requirement of reparameterization.

  1. Macroorganization of Chlorophyll a/b light-harvesting complex in thylakoids and aggregates: information from circular differential scattering

    SciTech Connect

    Garab, G.; Faludi-Daniel, A.; Sutherland, J.C.; Hind, G.

    1988-04-05

    Circular dichroism (CD) and magnetic circular dichroism (MCD) spectra were recorded for spinach thylakoids and for isolated, aggregated chlorophyll a/b light-harvesting pigment-protein complex, in random and magnetically aligned states of orientation at room and low temperatures. The shape and magnitude of the CD signal of most bands strongly depended on the orientation of the thylakoid membranes or the aggregated pigment-protein complex. In both thylakoids and aggregated light-harvesting complexes, however, the MCD spectra of the two different orientations were almost identical. Random and magnetically aligned samples exhibited anomalous, large CD signals outside the bands of pigment absorbance. Lack of similarity between the corresponding MCD and CD spectra showed that the large CD signals are not produced as a distortion of CD of absorbance by light scattering. Instead, these anomalous spectral features are believed to originate in differential selective scattering of circularly polarized light. The results lead to the conclusion that the light-harvesting pigment-protein complex in thylakoid grana forms a helical macroarray with dimensions commensurate with the wavelengths of the anomalous circular dichroism signals. A hypothesis is put forward suggesting a role for these macrodomains in granal organization.

  2. Partial purification of a spinach thylakoid protein kinase that can phosphorylate light-harvesting chlorophyll a/b proteins

    SciTech Connect

    Clark, R.D.; Hind, G.; Bennett, J.

    1985-01-01

    Protein phosphorylation in plant tissues is particularly marked in chloroplasts, protein kinase activity being associated with the outer envelope, the soluble stromal fraction, and the thylakoid membrane. Furthermore, thylakoid-bound activity probably includes several distinct kinases, as suggested by studies of divalent cation specificity and thermal lability carried out with intact thylakoids and by subfractionation of solubilized membranes. Illumination of thylakoids, particularly with red light, promotes the rapid and extensive phosphorylation of the light-harvesting chlorophyll a/b complex (LHCII) on a threonine residue near the amino terminus of the protein. This phosphorylation is thought to be involved in regulating the distribution of absorbed quanta between photosystems II and I and is modulated by the redox state of the thylakoid plastoquinone pool. Neither of the thylakoid kinases reported to date was capable of phosphorylating purified LHCII in vitro or of incorporating phosphate into threonyl residues of exogenous substrates, that some LHCII phosphorylation was catalyzed by a preliminary fraction led workers to suggest that at least one other kinase remained to be isolated. Here, the authors report the solubilization and partial purification of a protein kinase from spinach thylakoids that is capable of phosphorylating LHCII in vitro, and they show that the specific site of phosphorylation is very nearly the same as, if not identical with, the site phosphorylated in organello.

  3. Assessing the application of an airborne intensified multispectral video camera to measure chlorophyll a in three Florida estuaries

    SciTech Connect

    Dierberg, F.E.; Zaitzeff, J.

    1997-08-01

    After absolute and spectral calibration, an airborne intensified, multispectral video camera was field tested for water quality assessments over three Florida estuaries (Tampa Bay, Indian River Lagoon, and the St. Lucie River Estuary). Univariate regression analysis of upwelling spectral energy vs. ground-truthed uncorrected chlorophyll a (Chl a) for each estuary yielded lower coefficients of determination (R{sup 2}) with increasing concentrations of Gelbstoff within an estuary. More predictive relationships were established by adding true color as a second independent variable in a bivariate linear regression model. These regressions successfully explained most of the variation in upwelling light energy (R{sup 2}=0.94, 0.82 and 0.74 for the Tampa Bay, Indian River Lagoon, and St. Lucie estuaries, respectively). Ratioed wavelength bands within the 625-710 nm range produced the highest correlations with ground-truthed uncorrected Chl a, and were similar to those reported as being the most predictive for Chl a in Tennessee reservoirs. However, the ratioed wavebands producing the best predictive algorithms for Chl a differed among the three estuaries due to the effects of varying concentrations of Gelbstoff on upwelling spectral signatures, which precluded combining the data into a common data set for analysis.

  4. Cumulative effect of zinc oxide and titanium oxide nanoparticles on growth and chlorophyll a content of Picochlorum sp.

    PubMed

    Hazeem, Layla J; Bououdina, Mohammed; Rashdan, Suad; Brunet, Loïc; Slomianny, Christian; Boukherroub, Rabah

    2016-02-01

    The use of nanoparticles (NPs) is of increasing significance due to their large potential for various applications. Great attention should be paid on the possible impacts of nanoparticles on the environment as large amounts of them may reach the environment by accident or voluntarily. Marine algae are potential organisms for usage in nanopollution bioremediation in aquatic system, because of their ability to adapt to long exposure to NPs. Thus, it is of prime importance to study the possible interactions of different NPs with microalgae in assessing their potential environmental risks. Most studies on potential environmental effects of ZnO and TiO2 NPs have been performed independently and following the widely accepted, standardized test systems, which had been developed for the characterization of chemicals. In this study, we have examined the cumulative effect of ZnO and TiO2 NPs on Picochlorum sp. in addition to the individual effects of these NPs over 32 days. Our results indicate that the toxicity and availability of NPs to marine algae are reduced by their aggregation and sedimentation. NPs are found to have a negative effect on algal growth and chlorophyll a concentration during the early growth stages. In contrast, the case is reversed during the late growth stages. There is no significant difference between the effect of the NPs when they are used separately and when both ZnO and TiO2 are used together in the test (P > 0.05). PMID:26452656

  5. Chlorophyll a Simulation in a Lake Ecosystem Using a Model with Wavelet Analysis and Artificial Neural Network

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Wang, Xuan; Chen, Bin; Zhao, Ying; Yang, Zhifeng

    2013-05-01

    Accurate and reliable forecasting is important for the sustainable management of ecosystems. Chlorophyll a (Chl a) simulation and forecasting can provide early warning information and enable managers to make appropriate decisions for protecting lake ecosystems. In this study, we proposed a method for Chl a simulation in a lake that coupled the wavelet analysis and the artificial neural networks (WA-ANN). The proposed method had the advantage of data preprocessing, which reduced noise and managed nonstationary data. Fourteen variables were included in the developed and validated model, relating to hydrologic, ecological and meteorologic time series data from January 2000 to December 2009 at the Lake Baiyangdian study area, North China. The performance of the proposed WA-ANN model for monthly Chl a simulation in the lake ecosystem was compared with a multiple stepwise linear regression (MSLR) model, an autoregressive integrated moving average (ARIMA) model and a regular ANN model. The results showed that the WA-ANN model was suitable for Chl a simulation providing a more accurate performance than the MSLR, ARIMA, and ANN models. We recommend that the proposed method be widely applied to further facilitate the development and implementation of lake ecosystem management.

  6. Relationship between Chlorophyll a Concentration, Light Attenuation and Diving Depth of the Southern Elephant Seal Mirounga leonina

    PubMed Central

    Jaud, Thomas; Dragon, Anne-Cécile; Garcia, Jade Vacquie; Guinet, Christophe

    2012-01-01

    Recently, a number of Antarctic marine environmental studies have used oceanographic parameters collected from instrumented top predators for ecological and physical information. Phytoplankton concentration is generally quantified through active measurement of chlorophyll fluorescence. In this study, light absorption coefficient (K0.75) was used as an indicator of phytoplankton concentration. This measurement, easy to obtain and requiring low electric power, allows for assessing of the fine scale horizontal structuring of phytoplankton. As part of this study, Southern elephant seals (SES) were simultaneously equipped with a fluorometer and a light logger. Along the SES tracks, variations in K0.75 were strongly correlated with chlorophyll, a concentration measured by the fluorometer within the euphotic layer. With regards to SES foraging behaviour, bottom depth of the seal’s dive was highly dependent on light intensity at 150 m, indicating that the vertical distribution of SES’s prey such as myctophids is tightly related to light level. Therefore, change in phytoplankton concentration may not only have a direct effect on SES’s prey abundance but may also determine their vertical accessibility with likely consequences on SES foraging efficiency. PMID:23082166

  7. Estimation of chlorophyll-a concentration in case II waters using MODIS and MERIS data—successes and challenges

    NASA Astrophysics Data System (ADS)

    Moses, W. J.; Gitelson, A. A.; Berdnikov, S.; Povazhnyy, V.

    2009-10-01

    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 near-infrared wavelengths for the retrieval of chl- a concentration. The higher spatial resolution and the availability of a spectral band at around 708 nm with the MERIS data offered great promise for these models. We compared results from several different atmospheric correction procedures available for MODIS and MERIS data. No one particular procedure was consistently and systematically better than the rest. Nevertheless, even in the absence of a perfect atmospheric correction procedure, both the three-band and the two-band models showed promising results when compared with in situ chl- a measurements. The challenges and limitations involved in satellite remote monitoring of the chl- a distribution in turbid productive waters are discussed.

  8. Molecular cloning and characterization of the light-harvesting chlorophyll a/b gene from the pigeon pea (Cajanus cajan).

    PubMed

    Qiao, Guang; Wen, Xiao-Peng; Zhang, Ting

    2015-12-01

    Light-harvesting chlorophyll a/b-binding proteins (LHCB) have been implicated in the stress response. In this study, a gene encoding LHCB in the pigeon pea was cloned and characterized. Based on the sequence of a previously obtained 327 bp Est, a full-length 793 bp cDNA was cloned using the rapid amplification of cDNA ends (RACE) method. It was designated CcLHCB1 and encoded a 262 amino acid protein. The calculated molecular weight of the CcLHCB1 protein was 27.89 kDa, and the theoretical isoelectric point was 5.29. Homology search and sequence multi-alignment demonstrated that the CcLHCB1 protein sequence shared a high identity with LHCB from other plants. Bioinformatics analysis revealed that CcLHCB1 was a hydrophobic protein with three transmembrane domains. By fluorescent quantitative real-time polymerase chain reaction (PCR), CcLHCB1 mRNA transcripts were detectable in different tissues (leaf, stem, and root), with the highest level found in the leaf. The expression of CcLHCB1 mRNA in the leaves was up-regulated by drought stimulation and AM inoculation. Our results provide the basis for a better understanding of the molecular organization of LCHB and might be useful for understanding the interaction between plants and microbes in the future. PMID:26329890

  9. Wet Season Upwelling and Dry Season Chlorophyll-a Describe Interannual Growth Rates of Porites in Southern China

    PubMed Central

    Yang, Teng Teng; Goodkin, Nathalie Fairbank

    2014-01-01

    Southern China hosts coral communities in marginal environments that are characterized by low linear extension rates, low coral cover and/or no reef formation, thus providing natural laboratories to study coral communities with below average growth rates. Here we compare the annual linear extension rates over 10 years (range 1.2 to 11.4 mm yr−1) of six Porites sp. coral cores collected from Hong Kong with monthly hydrographic data from the Hong Kong Environmental Protection Department. At all sites, low-density, dry season extension were more variable than high-density, wet season extension and on average, was lower at two of the three sites. We applied multi-variate linear regressions that revealed high-density, wet season band extension to inversely correlate most significantly to temperature (r = −0.39, p<0.01). In contrast, low-density, dry season band extension was more variable and correlated most significantly with dry season chlorophyll-a (Chl-a) (r = 0.64, p<0.001). Additionally, we find that corals at the site with highest dry season Chl-a have the highest dry season extension lengths. Our findings indicate that relative mixing of fresh and salt water in the wet season and primary productivity in the dry season, and their influences on aragonite saturation, are likely to impact interannual coral extension variability in marginal environments. PMID:24901939

  10. Relationship between the Fluorescence Lifetime of Chlorophyll 'a' and Primary Productivity within the Mississippi River Plume and Adjacent Shelf Region

    NASA Technical Reports Server (NTRS)

    Hall, Callie; Miller, Richard L.; Fernandez, Salvador M.; McKee, Brent A.

    2000-01-01

    In situ measurements of chlorophyll fluorescence intensity have been widely used to estimate phytoplankton biomass. However, because the fluorescence quantum yield of chlorophyll a in vivo can be highly variable, measurements of chlorophyll fluorescence intensity cannot be directly correlated with phytoplankton biomass and do not provide information on the physiological state of the phytoplankton under study. Conversely, lifetime-based measurements of chlorophyll fluorescence provide a framework in which photosynthetic rates of phytoplankton can be analyzed according to phytoplankton physiology. Along with the measurement of primary production and ambient nutrient concentrations within the Mississippi River plume in the northern Gulf of Mexico, phytoplankton fluorescence lifetimes were measured using a Fluorescence Lifetime Phytoplankton Analyzer (developed under a NASA Small Business Innovative Research contract to Ciencia, Inc.). Variability of fluorescence lifetimes within the plume can be used as a background from which to interpret variations in the maximum quantum yield of photochemistry. The extent to which nutrient and effluent loading in this dynamic coastal area affect the photosynthetic performance of phytoplankton will be presented as a function of phytoplankton fluorescence lifetimes.

  11. Synthesis of thylakoid membrane proteins by chloroplasts isolated from spinach. Cytochrome b559 and P700-chlorophyll a-protein.

    PubMed

    Zielinski, R E; Price, C A

    1980-05-01

    Intact chloroplasts, purified from spinach leaves by sedimentation in density gradients of colloidal silica, incorporate labeled amino acids into at least 16 different polypeptides of the thylakoid membranes, using light as the only source of energy. The thylakoid products of chloroplast translation were visualized by subjecting membranes purified from chloroplasts labeled with [35S]methionine to electrophoresis in high-resolution, SDS-containing acrylamide gradient slab gels and autoradiography. The apparent mol wt of the labeled products ranged from less than 10,000 to greater than 70,000. One of the labeled products is the apoprotein of the P700-chlorophyll a-protein (CPI). The CPI apoprotein is assembled into a pigment-protein complex which is electrophoretically indistinguishable from the native CPI complex. Isolated spinach chloroplasts also incorporate [3H]leucine and [35S]methionine into cytochrome b559. The radioactive label remains with the cytochrome through all stages of purification: extraction of the thylakoid membranes with Triton X-100 and urea, adsorption of impurities on DEAE cellulose, two cycles of electrophoresis in Triton-containing polyacrylamide gels and electrophoresis in SDS-containing gradient gels. Cytochrome b559 becomes labeled with both [3H]leucine and [35S]methionine and accounts for somewhat less than 1% of the total isotopic incorporation into thylakoid protein. The lipoprotein appears to be fully assembled during the time-course of our labeling experiments. PMID:7372715

  12. Taxonomic and ecological relevance of the chlorophyll a fluorescence signature of tree species in mixed European forests.

    PubMed

    Pollastrini, Martina; Holland, Vera; Brüggemann, Wolfgang; Bruelheide, Helge; Dănilă, Iulian; Jaroszewicz, Bogdan; Valladares, Fernando; Bussotti, Filippo

    2016-10-01

    The variability of chlorophyll a fluorescence (ChlF) parameters of forest tree species was investigated in 209 stands belonging to six European forests, from Mediterranean to boreal regions. The modifying role of environmental factors, forest structure and tree diversity (species richness and composition) on ChlF signature was analysed. At the European level, conifers showed higher potential performance than broadleaf species. Forests in central Europe performed better than those in Mediterranean and boreal regions. At the site level, homogeneous clusters of tree species were identified by means of a principal component analysis (PCA) of ChlF parameters. The discrimination of the clusters of species was influenced by their taxonomic position and ecological characteristics. The species richness influenced the tree ChlF properties in different ways depending on tree species and site. Tree species and site also affected the relationships between ChlF parameters and other plant functional traits (specific leaf area, leaf nitrogen content, light-saturated photosynthesis, wood density, leaf carbon isotope composition). The assessment of the photosynthetic properties of tree species, by means of ChlF parameters, in relation to their functional traits, is a relevant issue for studies in forest ecology. The connections of data from field surveys with remotely assessed parameters must be carefully explored. PMID:27265248

  13. Examination of Critical Factors Related to Summer Chlorophyll a Concentration in the Sueo Dam Reservoir, Republic of Korea

    PubMed Central

    Lee, Seungjae; Lee, Sangeun; Kim, Sung Hoon; Park, Heekyung; Park, Sangjun; Yum, Kyungtaek

    2012-01-01

    Abstract This study examined critical factors related to the short-term variation of algae growth in reservoirs during the summer. To this end, statistical tests were carried out at a small dam reservoir to determine how chemical factors (e.g., nutrient concentrations) and physical factors (e.g., theoretical and relative residence times, temperature) influenced the chlorophyll a (Chl-a) concentration. Statistical tests revealed that, although phosphorus (P) concentration was significant for Chl-a, residence time had much stronger relationship to Chl-a concentration than chemical factors. In addition, the study verified that relative residence time (RRT) best explained the relation of water status to algae growth. RRT was found to be useful in identifying water status related to the summer algae bloom. Finally, this study raised the possibility of inhibiting summer algae growth by operating dam reservoirs moderately. These findings need to be seriously considered when reservoir operators establish effective strategies for water quality management in summer. PMID:22693417

  14. Relationship between chlorophyll a concentration, light attenuation and diving depth of the Southern elephant seal Mirounga leonina.

    PubMed

    Jaud, Thomas; Dragon, Anne-Cécile; Garcia, Jade Vacquie; Guinet, Christophe

    2012-01-01

    Recently, a number of Antarctic marine environmental studies have used oceanographic parameters collected from instrumented top predators for ecological and physical information. Phytoplankton concentration is generally quantified through active measurement of chlorophyll fluorescence. In this study, light absorption coefficient (K(0.75)) was used as an indicator of phytoplankton concentration. This measurement, easy to obtain and requiring low electric power, allows for assessing of the fine scale horizontal structuring of phytoplankton. As part of this study, Southern elephant seals (SES) were simultaneously equipped with a fluorometer and a light logger. Along the SES tracks, variations in K(0.75) were strongly correlated with chlorophyll, a concentration measured by the fluorometer within the euphotic layer. With regards to SES foraging behaviour, bottom depth of the seal's dive was highly dependent on light intensity at 150 m, indicating that the vertical distribution of SES's prey such as myctophids is tightly related to light level. Therefore, change in phytoplankton concentration may not only have a direct effect on SES's prey abundance but may also determine their vertical accessibility with likely consequences on SES foraging efficiency. PMID:23082166

  15. Chlorophyll-a Variability in the Southern Ocean Mixed Layer and Euphotic Zone From Elephant Seals and Profiling Floats

    NASA Astrophysics Data System (ADS)

    Carranza, M. M.; Gille, S. T.; Franks, P. J. S.; Johnson, K. S.; Girton, J. B.

    2015-12-01

    The Southern Ocean contains some of the ocean's deepest mixed layers. Because deep mixed layers can transport phytoplankton below the euphotic zone, light levels depend on mixed-layer depth (MLD), and phytoplankton growth is hypothesized to be co-limited by iron and light. Estimates of Chl-a fluorescence, particle backscattering and hydrographic profiles collected by southern elephant seals, EM-APEX, and biogeochemical Argo floats are used to evaluate the extent to which MLD influences phytoplankton bloom development and the vertical structure of chlorophyll-a (Chl-a) in the Southern Ocean. We find that surface Chl-a (i.e., mean Chl-a for the upper light penetration depth) is a relatively good proxy of phytoplankton biomass (i.e., depth-integrated Chl-a) within the euphotic zone but gives an inadequate representation of biomass within the mixed layer, particularly in the summer. Although nearly vertically homogeneous Chl-a within the mixed layer prevails in seasonal mean profiles, subsurface Chl-a maxima are not uncommon from spring through fall. Deep Chl-a maxima that correlate with particle backscattering in summer and fall are found near the base of the mixed layer, closer to the nutrient maximum than the light maximum, suggesting that nutrient limitation (i.e., essentially iron) can play a greater role than light limitation in governing productivity.

  16. Empirical and semi-analytical chlorophyll a algorithms for multi-temporal monitoring of New Zealand lakes using Landsat.

    PubMed

    Allan, Mathew G; Hamilton, David P; Hicks, Brendan; Brabyn, Lars

    2015-06-01

    The concentration of chlorophyll a (chl a; as a proxy for phytoplankton biomass) provides an indication of the water quality and ecosystem health of lakes. An automated image processing method for Landsat images was used to derive chl a concentrations in 12 Rotorua lakes of North Island, New Zealand, with widely varying trophic status. Semi-analytical and empirical models were used to process 137 Landsat 7 Enhanced Thematic Mapper (ETM+) images using records from 1999 to 2013. Atmospheric correction used radiative transfer modelling, with atmospheric conditions prescribed with Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and AIRS data. The best-performing semi-analytical and empirical equations resulted in similar levels of variation explained (r (2) = 0.68 for both equations) and root-mean-square error (RMSE = 10.69 and 10.43 μg L(-1), respectively) between observed and estimated chl a. However, the symbolic regression algorithm performed better for chl a concentrations <5 μg L(-1). Our Landsat-based algorithms provide a valuable method for synoptic assessments of chl a across the 12 lakes in this region. They also provide a basis for assessing changes in chl a individual lakes through time. Our methods provide a basis for cost-effective hindcasting of lake trophic status at a regional scale, informing on spatial variability of chl a within and between lakes. PMID:25986777

  17. Monomeric chlorophyll a enol: evidence for its possible role as the primary electron donor in photosystem I of plant photosynthesis

    SciTech Connect

    Wasielewski, M.R.; Norris, J.R.; Shipman, L.L.; Lin, C.P.; Svec, W.A.

    1981-05-01

    The chlorophyll a (Chl a) special-pair model of the primary donor of photosystem I (P700) does not account in a completely adequate fashion for the magnetic resonance properties observed for P700/sup +/. Enolization of the Chl a ring V ..beta..-keto ester results in a very different ..pi.. electronic structure. The ESR spectrum of the cation radical consists of a single 6.1-G gaussian line that is line narrowed relative to that of Chl a/sup +/ in a manner similar to P700/sup +/. Electron-nuclear double resonance (ENDOR) spectroscopy resolves only a 3.5-MHz hyperfine splitting for the 3-methyl group. The remaining splittings are all less than 3.5 MHz. Application of the special-pair model to the (/sup 13/C)P700/sup +/ second-moment data yields a 100% error. Ab initio molecular orbital calculations on ethyl chlorophyllide a enol cation bear out the ESR and ENDOR data. We conclude that a monomeric Chl a enol model provides a better description of the magnetic resonance parameters and oxidation potential of P700 than a Chl-a special-pair model.

  18. Use of fluorometrically determined gut chlorophyll-a concentrations to assess toxicity of sediments to the amphipod Ampelisca verrilli

    SciTech Connect

    Maier, P.P.; Van Dolah, R.F.; Jones, J.D.

    1995-12-31

    Concentrations of contaminants which do not cause measurable mortality in traditional acute bioassays may cause sublethal effects including reduction in the ability of amphipods to collect and ingest food. Measurement of feeding efficiency can provide an early indication of toxic stress and it may represent a more sensitive measure of sediment toxicity. Experiments conducted in this study utilize a fluorometric method of chlorophyll determination to quantify feeding of Ampelisca verrilli. Replicate 500 ml beakers with 150 ml of test or control sediment and 300 ml of seawater are inoculated with ten amphipods. At the end of a 96 hour exposure period, concentrated algae is added to bring each beaker concentration up to 500,000 cells/ml. After feeding for 1 hour, amphipods are collected by sieving and weighed. The animals from each container are then ground in buffered acetone, centrifuged, and the chlorophyll-a concentration of the supernatant is measured. The final concentrations are expressed as {micro}g chl-a/mg wet-weight of amphipod. Results obtained from feeding assays using toxic sediments will be compared with data obtained from standard 10-day sediment toxicity tests to evaluate the relative sensitivity of this sublethal endpoint.

  19. Knowledge Management and Reference Services

    ERIC Educational Resources Information Center

    Gandhi, Smiti

    2004-01-01

    Many corporations are embracing knowledge management (KM) to capture the intellectual capital of their employees. This article focuses on KM applications for reference work in libraries. It defines key concepts of KM, establishes a need for KM for reference services, and reviews various KM initiatives for reference services.

  20. Identification of nutrient deficiency in maize and tomato plants by in vivo chlorophyll a fluorescence measurements.

    PubMed

    Kalaji, Hazem M; Oukarroum, Abdallah; Alexandrov, Vladimir; Kouzmanova, Margarita; Brestic, Marian; Zivcak, Marek; Samborska, Izabela A; Cetner, Magdalena D; Allakhverdiev, Suleyman I; Goltsev, Vasilij

    2014-08-01

    The impact of some macro (Ca, S, Mg, K, N, P) and micro (Fe) nutrients deficiency on the functioning of the photosynthetic machinery in tomato (Solanum lycopersicum L.) and maize (Zea mays L.) plants grown in hydroponic cultures were investigated. Plants grown on a complete nutrient solution (control) were compared with those grown in a medium, which lacked one of macro- or microelements. The physiological state of the photosynthetic machinery in vivo was analysed after 14-days of deficient condition by the parameters of JIP-test based on fast chlorophyll a fluorescence records. In most of the nutrient-deficient samples, the decrease of photochemical efficiency, increase in non-photochemical dissipation and decrease of the number of active photosystem II (PSII) reaction centres were observed. However, lack of individual nutrients also had nutrient-specific effects on the photochemical processes. In Mg and Ca-deficient plants, the most severe decrease in electron donation by oxygen evolving complex (OEC) was indicated. Sulphur deficiency caused limitation of electron transport beyond PSI, probably due to decrease in the PSI content or activity of PSI electron acceptors; in contrary, Ca deficiency had an opposite effect, where the PSII activity was affected much more than PSI. Despite the fact that clear differences in nutrient deficiency responses between tomato and maize plants were observed, our results indicate that some of presented fluorescence parameters could be used as fluorescence phenotype markers. The principal component analysis of selected JIP-test parameters was presented as a possible species-specific approach to identify/predict the nutrient deficiency using the fast chlorophyll fluorescence records. PMID:24811616

  1. Femtosecond Nonlinear Optical Studies of Radiationless Decay in Carotenoids and in the Peridinin-Chlorophyll a Protein

    NASA Astrophysics Data System (ADS)

    Roscioli, Jerome D.; Ghosh, Soumen; Bishop, Michael M.; Beck, Warren F.; Frank, Harry A.

    2014-06-01

    Femtosecond transient-grating spectroscopy with optical heterodyne detection was employed to observe separately the time evolution of the absorption and dispersion components of the third-order nonlinear optical signal following resonant excitation of the S_2 (^1B_u^+) states of β-carotene in benzonitrile and peridinin in methanol using 40-fs pulses centered at 520 nm. The absorption and dispersion components exhibit distinctively different time profiles owing to the population of intermediate states. An initial intermediate state is populated on an ultrashort (<30 fs) time scale in both carotenoids. Owing to the fast red-shifting of the stimulated emission part of the S_2-state transient grating signal, we suggest that the intermediate state arises from vibrational displacements on the S_2-state potential surface that eventually yield twisted or bent conformations. Motions of the molecule of this type in the S_2-state would contribute to a mixing of the diabatic S_2 and S_1 electronic states and would promote the formation of intramolecular charge-transfer character. Both of these effects would enhance the efficiency of energy transfer from the S_1 state to the (B)Chl Q_y state in photosynthetic light-harvesting proteins. The time-resolved transient-grating spectra obtained for peridinin in the peridinin-chlorophyll a protein from Amphidinium carterae suggest a more rapid formation of the intermediate than for peridinin in methanol. This finding suggests that the conformation of the peridinin chromophore is controlled in the binding site to optimize the formation of the twisted intermediate upon excitation of the S_2 state. (Supported by grant DE-SC0010847 from the Department of Energy, Office of Basic Energy Sciences, Photosynthetic Systems program.)

  2. Generating a Long-Term Series of SST and Chlorophyll-A for the Coast of Ireland

    NASA Astrophysics Data System (ADS)

    Casal, G.; Furey, T.; Dabrowski, T.; Nolan, G.

    2015-04-01

    The use of remote sensing has increased greatly in recent years due to technological advances and its advantages in comparison with traditional methods. In the case of Ireland however the use of these techniques is not well established and only 17% of remote sensing studies are related to marine and coastal environments. As a first step, and taking into account that fisheries and aquaculture plays an important economic and social role in Ireland, a database of Sea Surface Temperature (SST) and Chlorophyll-a (Chl-a) relating to the ICES fisheries management areas is being generated. Up to now three different products have been produced. These products correspond to the annual SST Climatology and annual SST Anomalies from 1982 to 2014, as well as the annual Chl-a Climatology taking into account the different life span of CZCS (1982-1986), SeaWIFS (1997-2010), MERIS (2002-2012) and MODIS-Aqua (2002-2014). Initially, the Chl-a Climatology was produced for each sensor individually while the creation of a continuous Chl-a series will be investigated in the future. Analysing the SST trends highlighted an increasing trend in SST values in Irish waters, a trend which was more pronounced in the northern areas (+0.54 °C in the last 10 years). Although there are differences between sensors, Chl-a concentration seems to present higher values in the Celtic Sea since 2009. Analysing the ICES Divisions individually highlighted that coastal areas presented the highest Chl-a concentrations, involving a clear differentiation in the optical properties of coastal and oceanic waters.

  3. Cytokinins modulate the expression of genes encoding the protein of the light-harvesting chlorophyll a/b complex.

    PubMed

    de la Serve, B T; Axelos, M; Péaud-Lenoël, C

    1985-05-01

    Tobacco cell suspension cultures responded to cytokinins (for instance kinetin) by full chloroplast differentiation. The hormone had the effect of stimulating the appearance of a few prominent plastid proteins. Synthesis of the light-harvesting chlorophyl a/b-binding protein (LHCP) in response to kinetin was noteworthy (Axelos M. et al.: Plant Sci Lett 33:201-212, 1984).Poly(A)(+)RNAs were prepared from cells grown in the presence of or without added kinetin. Poly(A)(+)RNA recovery and translation activity were not quantitatively altered by the hormone treatment. In vitro translation of polyadenylated mRNA into precursor polypeptides of LHCP (pLHCP) was quantified by immunoprecipitation and SDS-PAGE fractionation of pLHCP immunoprecipitates: pLHCP-mRNA translating activity was found to be stimulated in parallel to mature LHCP accumulation by kinetin-induced cells.Dot-blot and northern-blot hybridizations of poly(A)(+)RNA were carried out, using as a probe a pea LHCP-cDNA clone (Broglie R. et al.: Proc Natl Acad Sci USA 78: 7304-7308, 1981). A ten-fold increase of the level of pLHCP-encoding sequences was observed in poly(A)(+)RNA prepared from 9-d kinetin-stimulated cells, compared to control cells. Oligo(dT)-cellulose-excluded RNA fractions exhibited very low hybridization levels, in the same ratios as those obtained with poly(A)(+)RNA.Thus, the expression of LHCP-gene activity, in response to kinetin addition to tobacco cell suspension cultures, is regulated by the level of pLHCP-encoding mRNA rather than by translational or post-translational controls. re]19850218 rv]19850605 ac]19850613. PMID:24306651

  4. Inter-annual variations in the SeaWiFS global chlorophyll a concentration (1997-2007)

    NASA Astrophysics Data System (ADS)

    Vantrepotte, V.; Mélin, F.

    2011-04-01

    The SeaWiFS data set covering the period 1997-2007 is used to develop a framework for a comprehensive description of the inter-annual variations in chlorophyll a concentration (Chl a). For each grid cell, the monthly Chl a series is decomposed into seasonal, irregular and trend-cycle terms with the Census X-11 technique that is an iterative band-pass filter algorithm. This approach allows variations in the annual cycle, while the trend-term isolates the multi-annual evolution in the mean level of the signal. The patterns with relatively large inter-annual variations are selected using the variance due to the trend-term with respect to the total variance, and are compared with maps of monotonic trends derived by a non-parametric Kendall analysis. Most of these patterns are identified in the subtropical domain (30°S-30°N), even though there are patterns with strong variations at mid-latitudes, particularly in the Northeast Atlantic and South of Australia. The time series found within each pattern of interest are found coherent. Conversely, the ensemble of spatially averaged time series of Chl a trend-terms shows a diversity of evolutions, with rather monotonic changes for all or part of the period, abrupt shifts or low-frequency oscillations, sometimes coupled with a modification in the amplitude of the annual cycle. Some of these series are correlated with climate indices, and those in subtropical regions usually show a negative correlation with the equivalent trend-term calculated for sea surface temperature. The identified inter-annual signals should be further monitored with longer time series and can serve as test cases for biogeochemical models.

  5. On the vertical distribution of the chlorophyll a concentration in the Mediterranean Sea: a basin scale and seasonal approach

    NASA Astrophysics Data System (ADS)

    Lavigne, H.; D'Ortenzio, F.; Ribera D'Alcalà, M.; Claustre, H.; Sauzède, R.; Gacic, M.

    2015-03-01

    The distribution of the chlorophyll a concentration ([Chl a]) in the Mediterranean Sea, which is mainly obtained from satellite surface observations or from scattered in situ experiments, is updated by analyzing a database of fluorescence profiles calibrated into [Chl a]. The database, which includes 6790 fluorescence profiles from various origins, was processed with a dedicated quality control procedure. To ensure homogeneity between the different data sources, 65% of fluorescence profiles have been inter-calibrated on the basis of their concomitant satellite [Chl a] estimation. The climatological pattern of [Chl a] vertical profile in four key sites of the Mediterranean Sea has been analyzed. Climatological results confirm previous findings on the range of [Chl a] values and on the main Mediterranean trophic regimes. It also provides new insights on the seasonal variability of the shape of the vertical [Chl a] profile, inaccessible from remote sensing observations. An analysis based on the recognition of the general shape of the fluorescence profile was also performed. Although the shape of [Chl a] vertical distribution characterized by a deep chlorophyll maximum (DCM) is ubiquitous during summer, different forms are observed during winter, suggesting thus that factors affecting the vertical distribution of the biomass are complex and highly variable. The [Chl a] distribution in the Mediterranean Sea mimics, at smaller scales, what is observed in the Global Ocean. As already evidenced by analyzing satellite surface observations, mid-latitude and subtropical like phytoplankton dynamics coexist in the Mediterranean Sea. Moreover, the Mediterranean DCM variability appears characterized by patterns already observed at global scale.

  6. On the vertical distribution of the chlorophyll a concentration in the Mediterranean Sea: a basin-scale and seasonal approach

    NASA Astrophysics Data System (ADS)

    Lavigne, H.; D'Ortenzio, F.; Ribera D'Alcalà, M.; Claustre, H.; Sauzède, R.; Gacic, M.

    2015-08-01

    The distribution of the chlorophyll a concentration ([Chl a]) in the Mediterranean Sea, mainly obtained from satellite surface observations or from scattered in situ experiments, is updated by analyzing a database of fluorescence profiles converted into [Chl a]. The database, which includes 6790 fluorescence profiles from various origins, was processed with a specific quality control procedure. To ensure homogeneity between the different data sources, 65 % of fluorescence profiles have been intercalibrated on the basis of their concomitant satellite [Chl a] estimation. The climatological pattern of [Chl a] vertical profiles in four key sites of the Mediterranean Sea has been analyzed. Climatological results confirm previous findings over the range of existing [Chl a] values and throughout the principal Mediterranean trophic regimes. They also provide new insights into the seasonal variability in the shape of the vertical [Chl a] profile, inaccessible through remote-sensing observations. An analysis based on the recognition of the general shape of the fluorescence profile was also performed. Although the shape of [Chl a] vertical distribution characterized by a deep chlorophyll maximum (DCM) is ubiquitous during summer, different forms are observed during winter, thus suggesting that factors affecting the vertical distribution of the biomass are complex and highly variable. The [Chl a] spatial distribution in the Mediterranean Sea mimics, on smaller scales, what is observed in the global ocean. As already evidenced by analyzing satellite surface observations, midlatitude- and subtropical-like phytoplankton dynamics coexist in the Mediterranean Sea. Moreover, the Mediterranean DCM variability appears to be characterized by patterns already observed on the global scale.

  7. Reference Assessment

    ERIC Educational Resources Information Center

    Bivens-Tatum, Wayne

    2006-01-01

    This article presents interesting articles that explore several different areas of reference assessment, including practical case studies and theoretical articles that address a range of issues such as librarian behavior, patron satisfaction, virtual reference, or evaluation design. They include: (1) "Evaluating the Quality of a Chat Service"…

  8. Reference Services.

    ERIC Educational Resources Information Center

    Bunge, Charles A.

    1999-01-01

    Discusses library reference services. Topics include the historical development of reference services; instruction in library use, particularly in college and university libraries; guidance; information and referral services and how they differ from traditional question-answering service; and future concerns, including user fees and the planning…

  9. Reference frames and reference networks

    NASA Astrophysics Data System (ADS)

    Bosy, Jaroslaw; Krynski, Jan

    2015-12-01

    The summary of research activities concerning reference frames and reference networks performed in Poland in a period of 2011-2014 is presented. It contains the results of research on implementation of IUGG2011 and IAU2012 resolutions on reference systems, implementation of the ETRS89 in Poland, operational work of permanent IGS/ EUREF stations in Poland, operational work of ILRS laser ranging station in Poland, active GNSS station networks in Poland, maintenance of vertical control in Poland, maintenance and modernization of gravity control, and maintenance of magnetic control in Poland. The bibliography of the related works is given in references.

  10. Vertical distribution of chlorophyll a concentration and phytoplankton community composition from in situ fluorescence profiles: a first database for the global ocean

    NASA Astrophysics Data System (ADS)

    Sauzède, R.; Lavigne, H.; Claustre, H.; Uitz, J.; Schmechtig, C.; D'Ortenzio, F.; Guinet, C.; Pesant, S.

    2015-04-01

    In vivo chlorophyll a fluorescence is a proxy of chlorophyll a concentration, and is one of the most frequently measured biogeochemical properties in the ocean. Thousands of profiles are available from historical databases and the integration of fluorescence sensors to autonomous platforms led to a significant increase of chlorophyll fluorescence profile acquisition. To our knowledge, this important source of environmental data has not yet been included in global analyses. A total of 268 127 chlorophyll fluorescence profiles from several databases as well as published and unpublished individual sources were compiled. Following a robust quality control procedure detailed in the present paper, about 49 000 chlorophyll fluorescence profiles were converted in phytoplankton biomass (i.e. chlorophyll a concentration) and size-based community composition (i.e. microphytoplankton, nanophytoplankton and picophytoplankton), using a~method specifically developed to harmonize fluorescence profiles from diverse sources. The data span over five decades from 1958 to 2015, including observations from all major oceanic basins and all seasons, and depths ranging from surface to a median maximum sampling depth of around 700 m. Global maps of chlorophyll a concentration and phytoplankton community composition are presented here for the first time. Monthly climatologies were computed for three of Longhurst's ecological provinces in order to exemplify the potential use of the data product. Original data sets (raw fluorescence profiles) as well as calibrated profiles of phytoplankton biomass and community composition are available in open access at PANGAEA, Data Publisher for Earth and Environmental Science. Raw fluorescence profiles: http://doi.pangaea.de/10.1594/PANGAEA.844212 and Phytoplankton biomass and community composition: http://doi.pangaea.de/10.1594/PANGAEA.844485.