Leaf chlorophyll content as a proxy for leaf photosynthetic capacity.

Improving the accuracy of estimates of forest carbon exchange is a central priority for understanding ecosystem response to increased atmospheric CO2 levels and improving carbon cycle modelling. However, the spatially continuous parameterization of photosynthetic capacity (Vcmax) at global scales and appropriate temporal intervals within terrestrial biosphere models (TBMs) remains unresolved. This research investigates the use of biochemical parameters for modelling leaf photosynthetic capacity within a deciduous forest. Particular attention is given to the impacts of seasonality on both leaf biophysical variables and physiological processes, and their interdependent relationships. Four deciduous tree species were sampled across three growing seasons (2013-2015), approximately every 10 days for leaf chlorophyll content (ChlLeaf ) and canopy structure. Leaf nitrogen (NArea ) was also measured during 2014. Leaf photosynthesis was measured during 2014-2015 using a Li-6400 gas-exchange system, with A-Ci curves to model Vcmax. Results showed that seasonality and variations between species resulted in weak relationships between Vcmax normalized to 25°C (Vcmax25) and NArea (R2  = 0.62, P < 0.001), whereas ChlLeaf demonstrated a much stronger correlation with Vcmax25 (R2  = 0.78, P < 0.001). The relationship between ChlLeaf and NArea was also weak (R2  = 0.47, P < 0.001), possibly due to the dynamic partitioning of nitrogen, between and within photosynthetic and nonphotosynthetic fractions. The spatial and temporal variability of Vcmax25 was mapped using Landsat TM/ETM satellite data across the forest site, using physical models to derive ChlLeaf . TBMs largely treat photosynthetic parameters as either fixed constants or varying according to leaf nitrogen content. This research challenges assumptions that simple NArea -Vcmax25 relationships can reliably be used to constrain photosynthetic capacity in TBMs, even within the same plant functional type. It is suggested that ChlLeaf provides a more accurate, direct proxy for Vcmax25 and is also more easily retrievable from satellite data. These results have important implications for carbon modelling within deciduous ecosystems

Remote sensing retrieval of winter wheat leaf area index and canopy chlorophyll density at different growth stages

Leaf area index (LAI) and canopy chlorophyll density (CCD) are key indicators of crop growth status. In this study, we compared several vegetation indices and their red-edge modified counterparts to evaluate the optimal red-edge bands and the best vegetation index at different growth stages. The indices were calculated with Sentinel-2 MSI data and hyperspectral data. Their performances were validated against ground measurements using R2, RMSE, and bias. The results suggest that indices computed with hyperspectral data exhibited higher R2 than multispectral data at the late jointing stage, head emergence stage, and filling stage. Furthermore, red-edge modified indices outperformed the traditional indices for both data genres. Inversion models indicated that the indices with short red-edge wavelengths showed better estimation at the early jointing and milk development stage, while indices with long red-edge wavelength estimate the sought variables better at the middle three stages. The results were consistent with the red-edge inflection point shift at different growth stages. The best indices for Sentinel-2 LAI retrieval, Sentinel-2 CCD retrieval, hyperspectral LAI retrieval, and hyperspectral CCD retrieval at five growth stages were determined in the research. These results are beneficial to crop trait monitoring by providing references for crop biophysical and biochemical parameters retrieval

Determination of chlorophyll content in selected grass communities of Krkonoše tundra based on field spectroscopy and aerial hyperspectral data

The thesis focuses on the determination of chlorophyll content from hyperspectral data in grass communities in the arctic-alpine tundra in the Krkonoše Mountains, namely Nardus stricta, Molinia caerulea, Calamagrostis villosa, and Deschampsia cespitosa. Leaf chlorophyll content (LCC) was measured using two methods - spectrophotometric destructive determination in the laboratory, and the LCC assessed non-destructively by fluorescence portable chlorophyll meter CCM-300. Leaf area index (LAI) values for canopy chlorophyll content (CCC) retrieval were also acquired by destructive biomass sampling and indirectly using LAI-2200C. Relationships were established between the LCCs, LAI, CCCs, and vegetation indices (VI) calculated from respective spectra, i.e. leaf level spectra acquired with contact probe coupled with an ASD FieldSpec4 Wide-Res spectroradiometer, canopy level spectra measured by the spectroradiometer and extracted from hyperspectral images (HSI) acquired by Headwall Nano- Hyperspec® mounted on the DJI Matrice 600 Pro drone. Chlorophyll content maps were created based on the results of multiple stepwise linear regression applied to HSI. For the model, derived from the non-destructive data sampling and used for the LCC map, a RMSE of 66.55 mg/m2 was achieved. Keywords: leaf chlorophyll...Diplomová práce se zaměřuje na stanovení obsahu chlorofylu z hyperspektrálních dat v travních společenstvech krkonošské tundry, jmenovitě smilky tuhé (Nardus stricta), bezkolence modrého (Molinia caerulea), třtiny chloupkaté (Calamagrostis villosa) a metlice trsnaté (Deschampsia cespitosa). Hodnoty obsahu chlorofylu na úrovni listu (LCC) byly naměřeny destruktivně spektrofotometricky v laboratoři a nedestruktivně chlorofylmetrem CCM-300. Hodnoty indexu listové plochy (LAI) pro výpočet obsahu chlorofylu na úrovni porostu (CCC) byly stanoveny taktéž destruktivně na základě odběru biomasy a nedestruktivně přístrojem LAI-2200C. Práce se věnuje popisu vlastností naměřených hodnot LCC, LAI a CCC a jejich korelací s vegetačními indexy odvozenými z příslušných spekter, tj. spekter na úrovni listu naměřených kontaktní sondou spektroradiometru ASD FieldSpec 4 Wide-Res, na úrovni porostu pořízených optickým kabelem a vyextrahovaných spekter z hyperspektrálních snímků (HSI) pořízených kamerou Headwall Nano-Hyperspec® upevněnou na dronu DJI Matrice 600 Pro. Práce zahrnuje vytvoření chlorofylových map na základě výsledku modelu mnohonásobné krokové lineární regrese (MSLR) aplikované na HSI. Pro model odvozený z nedestruktivního sběru dat využitý pro mapu LCC bylo dosaženo RMSE 66,55 mg/m2 . Klíčová slova: obsah...Department of Applied Geoinformatics and CartographyKatedra aplikované geoinformatiky a kartografieFaculty of SciencePřírodovědecká fakult

Desarrollo de estrategías analíticas para la identificación de contaminantes emergentes

En la presente Tesis, se han desarrollado diferentes métodos para identificar la presencia de contaminantes procedentes de diferentes fuentes naturales. Los métodos desarrollados han sido abordados utilizando dos metodologías: (i) IT-SPME acoplado a CapLC y UHPLC con detección DAD y MS, y (ii) dispositivos de análisis in situ. La estrategia basada en el acoplamiento entre IT-SPME y CapLC y UHPLC se ha utilizado para la estimación de la presencia de contaminantes (pesticidas como triazinas, nitroanilina, fenilureas y organofosforados, y plastificantes como productos de degradación del DEHP y principalmente DEHP) en muestras de aguas superficiales, de aguas de depuradoras, biota y sedimentos. Los analisis in situ permiten la estimación de varios contaminantes por inspección visual o con técnicas espectroscópicas (FTIR-ATR y UV-Vis). Los contaminantes analizados en efluentes de industrias lácteas fueron grasa y caseína, por otro lado se analizó N-(3-aminopropil)-N-dodecil-1,3-propanediamina (ADP) en aguas residuales procedentes de industrias cosméticas. La grasa se ha determinado con FTIR-ATR, además la caseína y la ADP se han analizado con un sensor polimérico compuesto por PDMS, TEOS, NQS y SiO2NPs. Por otro lado, también se ha utilizado el análisis in situ para conocer el daño producido por diferentes pesticidas a las hojas de espinacas, para ello, se ha desarrollado un método HPCIM para determinar Chl a ya que el contenido de este pigmento es una manera de evaluar el estado de salud de las plantas. Las principales ventajas de los métodos desarrollados en esta Tesis son la simplicidad, sensibilidad y la reducción al mínimo del tratamiento de muestra. Además, los métodos permiten análisis rápidos de contaminantes en diferentes tipos de muestras. El análisis con el acoplamiento IT-SPME-CapLC y IT-SPME-UHPLC se puede llevar a cabo en menos de 30 minutos. Adicionalmente, varias muestras se pueden analizar en menos de 15 minutos utilizando los métodos de análisis in situ propuestos.The environment is an essential support for human life and ecosystems. Currently, human activities such as agriculture, industry and infrastructure construction, among others, are dangerously affecting the environment, and for this reason continued monitoring may be necessary. To obtain up-to-date information about the state of the environment, the study of different environmental matrices such as water, biota, soils, sediments and air, is essential. In the present Thesis, different methods to determine several contaminants in environmental matrices from different sources have been developed. The methods developed have been addressed by using two approaches: (i) IT-SPME coupled to CapLC and UHPLC with DAD and MS detection, and (ii) in situ analysis devices. The strategy based on the coupling between IT-SPME and CapLC and UHPLC has been utilized to estimate the presence of contaminants (pesticides such as triazines, nitroaniline, phenylureas and organophosphorous, and plasticisers such as degradation products of DEHP and mainly DEHP) in surface water, wastewater from sewage treatment plant, biota and sediments samples. The in situ analyses have allowed the stimation of several contaminants by visual detection or with spectroscopic techniques (FTIR-ATR and UV-Vis spectrophotometry). The pollutants analysed were fat and casein in effluents from dairy industry and the biocide N-(3-aminopropyl)-N-dodecyl-1,3-propanediamine (ADP) in cosmetic wastewaters. Fat has been determined by FTIR-ATR, furthermore casein and ADP have been analysed with a polymeric sensor composed by PDMS, TEOS, NQS and SiO2NPs. On the other hand, the on-site analysis have also been utilized to know damage produced by different pesticides in spinach leaves; for this purpose, a H-point curve isolation method (HPCIM) have been developed to determine Chl a because the content of this pigment is a way to evaluate the health status of plants. The main advantages of the developed procedures in this Thesis are simplicity, sensitivity and also, the sample treatment is reduced to minimum. Furthermore, the methods allow rapid analysis of contaminants in different types of samples. The analysis with coupling IT-SPME-CapLC and IT-SPME-UHPLC can be carried out in less than 30 min. In addition, several samples can be analysed in less than 15 min using the proposed on-site analysis

Desarrollo de nuevas estrategias para el diseño de técnicas de cromatografía líquida miniaturizada en línea: nanopartículas, contaminación secundaria

In recent years one of the most important trends in Analytical Chemistry has been the development of new analytical methodologies based on the miniaturization, simplification and automatization of the analytical process, in order to reduce the environmental impact of the analysis without compromising the sensitivity and selectivity. In this respect miniaturized liquid chromatography (LC) systems, such as capillary liquid chromatography (CapLC) and nanoliquid chromatography (NanoLC) are important achievements. These techniques are environmental friendly because the amount of material involved is limited and organic solvents, electricity and the wastes generated are lower than in conventional scale LC. In addition, CapLC and NanoLC provide an improvement of the sensitivity and even selectivity with respect to conventional LC. On the other hand, sample treatment is one of the most important steps of analytical process; as it is usually necessary to eliminate most endogenous compounds and to concentrate analytes, which are often present at low concentrations in the sample. Sample treatment is typically the most time-consuming step of the analytical process. This is because conventional off-line sample preparation techniques generally require laborious procedures that are susceptible to produce analyte loss and contamination. In addition, most of them are difficult to automatize. Therefore, these methodologies are gradually being replaced by solid-phase microextraction (SPME), a green approach to sample preparation which minimizes solvent consumption and generation of wastes. SPME is also less time consuming and more cost effective than traditional procedures. In-tube solid-phase microextraction (IT-SPME) is an interesting alternative to other SPME techniques, because it combines miniaturization, automation and reduction of solvent consumption, and it can be also coupled to LC systems. The limited number of extraction columns available is the most important limitation of IT-SPME, paticularly coupled to CapLC and NanoLC. Therefore, it is necessary to develop new sorbents for IT-SPME. The research carried out in the course of the present thesis has been mainly focused on the development of new strategies for the implementation of IT-SPME through new configurations of coupling and the synthesis of new extractive phases or the reutilization of waste (ashes). More specifically, the research has been intended to facilitate the on-line coupling of IT-SPME to miniaturized LC equipments, as well as to develop in situ non-invasive strategies for the analysis of different pollutants and wastes. Special attention has been developed to polar compounds because of their high mobility in the environment. In some cases, the studies have been extended to their degradation products. Therefore, this thesis is intended to improve knowledge about IT-SPME, exploring new materials as extractive phases, as well as to consolidate the coupling with miniaturized LC, especially NanoLC and others techniques amenable for in situ or non-invasive studies, and from a perspective of the Green Analytical Chemistry principles