Search results for "Chlorophyll"
showing 10 items of 453 documents
Towards the development of a biogeochemical model for addressing the eutrophication problems in the shallow hypertrophic lagoon of Albufera de Valenc…
2015
Abstract Our study presents a biogeochemical model that aims to reproduce the ecological processes shaping phytoplankton dynamics in the shallow hypertrophic lagoon of Albufera de Valencia (Spain). The model simulates two elemental cycles (N and P), two phytoplankton groups (cyanobacteria and non-cyanobacteria), and heterotrophic bacteria. First, we examine the capacity to reproduce the observed plankton patterns, while accommodating the uncertainty related to the external forcing factors of our model (hydraulic and nutrient loading, zooplankton grazing). Sensitivity analysis is also performed to identify the most influential parameters and therefore to shed light on the knowledge needed to…
Contributions of autochthonous and allochthonous sources to dissolved organic matter in a large, shallow, eutrophic lake with a highly calcareous cat…
2013
We traced the origin of dissolved organic matter (DOM) in the large, shallow, eutrophic Lake Vortsjarv in Estonia. Allochthonous DOM (Al-DOM) had higher δ13C values than autochthonous DOM (Au-DOM). The δ13C of inflow DOM varied from −28.2‰ to −25.4‰ (mean −26.7‰) and in-lake DOM varied from −28.4‰ to −26.1‰ (mean −27.2‰). Low stable isotope (SI) signatures of Au-DOM were caused by relatively 13C-depleted values of its precursors (mainly phytoplankton) with mean δ13C of −28.9‰. SI signatures of dissolved inorganic carbon (DIC) in the inflows and in the lake were also relatively low (from −15.1‰ to −3.28‰). SI values of DOM were lower during the active growing season from May to September and…
The effect of mariculture facilities on biochemical features of suspended organic matter (southern Tyrrhenian, Mediterranean)
2006
Abstract A comparison of a Mediterranean aquaculture impacted area and control areas was made to assess the effect of fish farm waste discharge on the biochemical features of the water column. Trophic variables commonly used in marine ecology such as total suspended matter, suspended chlorophyll- a , biochemical features of particulate organic matter (proteins, lipids and carbohydrates) and biopolymeric carbon were chosen as the best descriptors of trophic conditions. An initial analysis of data from the impact area was carried out in order to test the effect of farm waste using a gradient of distances downstream from the fish farm cages (50 m, 300 m, 1000 m). The results were then compared…
Denoising AVIRIS-NG Data for Generation of New Chlorophyll Indices
2021
The availability of Airborne Visible and Infrared Imaging Spectrometer-Next Generation (AVIRIS-NG) data has enormous possibilities for quantification of Leaf Chlorophyll Content (LCC). The present study used the AVIRIS-NG campaign site of Western India for generation and validation of new chlorophyll indices by denoising the AVIRIS-NG data. For validation, concurrent to AVIRIS-NG flight overpass, field samplings were performed. The acquired AVIRIS-NG was subjected to Spectral Angle Mapper (SAM) classifier for discriminating the crop types. Three smoothing techniques i.e., Fast-Fourier Transform (FFT), Mean and Savitzky-Golay filters were evaluated for their denoising capability. Raw and fil…
CEFLES2: The remote sensing component to quantify photosynthetic efficiency from the leaf to the region by measuring sun-induced fluorescence in the …
2009
The CEFLES2 campaign during the Carbo Europe Regional Experiment Strategy was designed to provide simultaneous airborne measurements of solar induced fluorescence and CO<sub>2</sub> fluxes. It was combined with extensive ground-based quantification of leaf- and canopy-level processes in support of ESA's Candidate Earth Explorer Mission of the "Fluorescence Explorer" (FLEX). The aim of this campaign was to test if fluorescence signal detected from an airborne platform can be used to improve estimates of plant mediated exchange on the mesoscale. Canopy fluorescence was quantified from four airborne platforms using a combination of novel sensors: (i) the prototype ai…
Calibration of in situ chlorophyll fluorometers for organic matter
2019
AbstractOrganic matter (OM) other than living phytoplankton is known to affect fluorometric in situ assessments of chlorophyll in lakes. For this reason, calibrating fluorometric measurements for OM error is important. In this study, chlorophyll (Chl) fluorescence was measured in situ in multiple Finnish lakes using two sondes equipped with Chl fluorometers (ex.470/em.650–700 nm). OM absorbance (A420) was measured from water samples, and one of the two sondes was also equipped with in situ fluorometer for OM (ex.350/em.430 nm). The sonde with Chl and OM fluorometers was also deployed continuously on an automated water quality monitoring station on Lake Konnevesi. For data from multiple lake…
Seasonal Mapping of Irrigated Winter Wheat Traits in Argentina with a Hybrid Retrieval Workflow Using Sentinel-2 Imagery
2022
Earth observation offers an unprecedented opportunity to monitor intensively cultivated areas providing key support to assess fertilizer needs and crop water uptake. Routinely, vegetation traits mapping can help farmers to monitor plant development along the crop’s phenological cycle, which is particularly relevant for irrigated agricultural areas. The high spatial and temporal resolution of the Sentinel-2 (S2) multispectral instrument leverages the possibility to estimate leaf area index (LAI), canopy chlorophyll content (CCC), and vegetation water content (VWC) from space. Therefore, our study presents a hybrid retrieval workflow combining a physically-based strategy with a machine learni…
FluorMODgui V3.0 : a graphic user interface for the spectral simulation of leaf and canopy chlorophyll fluorescence
2006
The FluorMODgui Graphic User Interface (GUI) software package developed within the frame of the FluorMOD project Development of a Vegetation Fluorescence Canopy Model is presented in this manuscript. The FluorMOD project was launched in 2002 by the European Space Agency (ESA) to advance the science of vegetation fluorescence simulation through the development and integration of leaf and canopy fluorescence models based on physical methods. The design of airborne or space missions dedicated to the measurement of solar-induced chlorophyll fluorescence using remote-sensing instruments require physical methods for quantitative feasibility analysis and sensor specification studies. The FluorMODg…
Effect of nitrogen fertilizer level on quality and shelf-life of fresh cut Swiss chard
2018
Swiss chard (Beta vulgaris L. var. cicla L.) is a leafy vegetable highly appreciated in some areas for its nutritional properties and year round supply. Its production area is not commercially important, but this minor vegetable offers an interesting enlargement of the current vegetable assortment by using its stalks and leaves. Swiss chard is a very nutritive demanding species. The content of mineral elements, total quality and yield are influenced by the amount, frequency and method of fertilization. The aim of this study was to evaluate the effect of high or low levels of nitrogen fertilization on the quality and shelf-life of minimally processed Swiss chard. Plants grown with a high (18…
MORPHO-FUNCTIONAL PATTERNS OF PHOTOSYNTHESIS IN THE SOUTH PACIFIC KELPLESSONIA NIGRESCENS: EFFECTS OF UV RADIATION ON14C FIXATION AND PRIMARY PHOTOCH…
2007
The morpho-functional patterns of photosynthesis, measured as 14C-fixation and chl fluorescence of PSII, also as affected by different doses of UV radiation in the laboratory were examined in the South Pacific kelp Lessonia nigrescens Bory of the coast of Valdivia, Chile (40°S). The results indicated the existence of longitudinal thallus profiles in physiological performance. In general, blades exhibited higher rates of carbon fixation and pigmentation as compared with stipes and holdfasts. Light-independent 14C fixation (LICF) was high in meristematic zones of the blades (3.5 μmol 14C·g−1 fresh weight [FW]·h−1), representing 2%–16% (percentage ratio) of the photosynthetic 14C fixation (20 …