Search results for "fosfor"
showing 10 items of 77 documents
Biogēno elementu akumulācija Baltijas jūras un Rīgas līča sedimentos
2022
Katru gadu Baltijas jūrā un Rīgas līcī ieplūst liels apjoms fosfora, slāpekļa un oglekļa. Šīs vielas ne tikai veicina eitrofikāciju un mirušo zonu izveidi, bet arī negatīvi ietekmē Baltijas jūras un Rīgas līča ekosistēmu. Ņemot vērā biogēno elementu slodžu apjomu ir būtiski sekot līdzi to akumulācijas tendencēm sedimentos, jo tas ir ļoti būtisks process elementu izņemšanai no ekosistēmas. Bakalaura darba izstrādes laikā iepriekš ievāktajiem Baltijas jūras un Rīgas līča sedimentu paraugiem tiek veiktas ķīmiskās analīzes un noteikts tajos esošais fosfora un slāpekļa daudzums. Sedimentu paraugi kopā tika ievākti no 19 stacijām, taču šajā darbā tiks analizēti un pētīti četru staciju paraugi. Di…
Baltalkšņu Alnus incana ietekme uz dažāda granulometriskā sastāva augšņu īpašībām pamestās lauksaimniecības zemēs
2019
Latvijā aktuāla problēma ir lauksaimniecības zemju aizaugšana ar baltalksni Alnus incana (L.) Moench. Maģistra darba ietvaros ir pētīta baltalkšņu ietekme uz smilts un mālsmilts augsnēm. Darbs sastāv no 37 tabulām, 32 attēliem un 53 pielikumiem, kuros attainoti pētījumā iegūtie rezultāti. Pētījumu rezultātā tika pierādīts, ka 15 – 20 gadu laikā lauksaimniecības zemei apmežojoties ar baltalksni, Cambisols smilts augsnē būtiski palielinās slāpekļa, oglekļa un kālija saturs. 11-20 cm augsnes slānī būtiski ir palielinājies arī fosfora saturs Cambisols smilts augsnē. Phaeozems smagas mālsmilts augsnē slāpekļa, oglekļa un kālija saturs augsnē ir palielinājies, taču ne būtiski. Pētījumu rezultātā …
α-Aminophosphonates, Phosphinates, and Phosphine Oxides as Extraction and Precipitation Agents for Rare Earth Metals, Thorium, and Uranium : A Review
2022
α-Aminophosphonates, -phosphinates, and -phosphine oxides are a group of organophosphorus compounds that were investigated as extraction agents for rare earth (RE) metals and actinoids for the first time in the 1960s. However, more systematic investigations of their extraction properties towards REs and actinoids were not started until the 2010s. Indeed, recent studies have shown that these α-amino-functionalized compounds can outperform the commercial organophosphorus extraction agents in RE separations. They have also proven to be very efficient extraction and precipitation agents for recovering Th and U from RE concentrates. These actinoids coexist with REs in some of the commercially im…
OZNACZANIE ZWIĄZKÓW FOSFORU W MATRYCACH ROŚLINNYCH
2021
The variety of the chemical forms of phosphorus compounds occurring in plant tissues, accompanied by the complexity of the chemical composition of plants as the analytical matrices, are the reasons why there is no one, the best answer, how those individual substances may be determined qualitatively and quantitatively. Interestingly, if the subject of determination is the total phosphorus content, the spectrum of effective methods and techniques seems to be impressive. However, in case of spectrophotometric measurements and classical variants of absorption (FAAS) or emission (ICP-AES/ ICP-OES) spectrometry techniques, it is necessary at first to isolate various phosphorus forms from the matr…
Density-functional tight-binding modeling of electromechanics of phosphorene
2018
Single-layer black phosphorus or phosphorene is a two-dimensional material made from a puckered honeycomb structure. It is a semiconductor with a tunable band gap and both its mechanical and electronic properties are highly asymmetric because of the puckering. Recently there has been numerous computational studies and some experimental works trying to bring deeper understanding about this relatively new 2D material. In this study we simulate phosphorene using computationally low-cost density functional tight-binding (DFTB) method to see how stretching, shearing and bending affect its electronic properties. The band structure analysis shows that there is a relation between shearing and bendi…
Degradazione di pesticidi organofosforici in matrici ambientali
2008
Matrici quali acqua, suolo ed aria sono costantemente soggette a forti pressioni antropiche. I pesticidi pur avendo apportato grandi benefici alle attività agricole influiscono negativamente sugli equilibri degli ecosistemi. Circa 85-90% dei principi attivi applicati in agricoltura non raggiunge gli organismi a cui sono destinati, ma viene disperso nell’ambiente. In tale contesto l’individuazione di microrganismi deputati alla loro degradazione diventa un importante mezzo per la salvaguardia ambientale e della salute umana. Lo scopo del presente lavoro è stato quello di isolare batteri del suolo capaci di degradare composti organofosforici, i quali rivestono una notevole importanza nelle pr…
Ekstrakcja fosforu z osadów ściekowych i popiołów ze spalania osadów - analiza problemu
2016
Fosfor jako pierwiastek niezbędny do produkcji rolniczej, w miarę wyczerpywania się zasobów fosforytów, staje się komponentem coraz bardziej deficytowym. Koniecznym wydaje się wdrożenie metod taniego i efektywnego odzysku tego pierwiastka z wszelkiego rodzaju odpadów. Szczególnie cennym źródłem fosforu są popioły z osadów ściekowych i same osady. Optymalizacja metod sekwencyjnej ekstrakcji fosforu zawartego w popiele z termicznego przekształcania osadów ściekowych i odwodnionych osadów pozwala na wybór efektywnej i nieskomplikowanej technologicznie możliwości odzysku fosforu, przy jednoczesnym zachowaniu niskiego obciążenia eluatu metalami ciężkimi, które są jedną z głównych przyczyn ograni…
RAVITA Technology : new innovation for combined phosphorus and nitrogen recovery
2018
Abstract Present phosphorus (P) recovery technologies mainly contain P recovery from sludge liquor or ash. These types of technologies are suitable for large wastewater treatment plants (WWTPs) with enhanced biological phosphorus removal (EBPR), digestion and/or incineration. In Finland and other Nordic countries, strict P discharge limits require chemical precipitation, thus EBPR alone is not sufficient. Ammonium recovery from wastewater, on the other hand, is not so often discussed. However, recovery from WWTP reject waters would decrease the energy demand of ammonium synthesis by Haber-Bosh technology and the energy demand of the WWTP's biological process. Helsinki Region Environmental S…
Temperature, phosphorus and species composition will all influence phytoplankton production and content of polyunsaturated fatty acids
2023
Temperature increases driven by climate change are expected to decrease the availability of polyunsaturated fatty acids in lakes worldwide. Nevertheless, a comprehensive understanding of the joint effects of lake trophic status, nutrient dynamics and warming on the availability of these biomolecules is lacking. Here, we conducted a laboratory experiment to study how warming (18–23°C) interacts with phosphorus (0.65–2.58 μM) to affect phytoplankton growth and their production of polyunsaturated fatty acids. We included 10 species belonging to the groups diatoms, golden algae, cyanobacteria, green algae, cryptophytes and dinoflagellates. Our results show that both temperature and phosphorus w…
Is there light after depth? Distribution of periphyton chlorophyll and productivity in lake littoral zones
2014
Periphyton and phytoplankton contribute to the base of lake food webs, and both groups of microalgae are influenced by resources and physical forcing. Spatial variation in light availability interacts with the physical dynamics of the water column to create predictable depth gradients in resources and disturbance that may differentially affect periphyton vs phytoplankton. We characterized the depth distribution of chlorophyll and productivity of periphyton on sediments (epipelon) and phytoplankton in the euphotic zones of 13 oligomesotrophic lakes that span a large size gradient (0.017–32,600 km2 ). Epipelic chlorophyll usually increased with depth in the epilimnion. Light was the primary d…