Oskars Purmalis

Structural Characterization and Chemical Classification of Some Bryophytes Found in Latvia

Bryophytes are the second largest taxonomic group in the plant kingdom; yet, studies conducted to better understand their chemical composition are rare. The aim of this study was to characterize the chemical composition of bryophytes common in Northern Europe by using elemental, spectral, and non‐destructive analytical methods, such as Fourier transform IR spectrometry (FT‐IR), solid‐phase 13C‐NMR spectrometry, and pyrolysis‐gas chromatography/mass spectrometry (Py‐GC/MS), for the purpose of investigating their chemotaxonomic relationships on the basis of chemical‐composition data. The results of all these analyses showed that bryophytes consist mainly of carbohydrates. Judging by FT‐IR spectra, the OH groups in combination of CO groups were the most abundant groups. The 13C‐NMR spectra provided information on the presence of such compounds as phenolics and lipids. It was found that the amount of phenolic compounds in bryophytes is relatively small. This finding definitely confirmed the absence of lignin in the studied bryophytes. Cluster analysis was used to better understand differences in the chemical composition of bryophyte samples and to evaluate possible usage of these methods in the chemotaxonomy of bryophytes.

Experimental Study of Peat Humification Indicators

Experimental Study of Peat Humification Indicators An important parameter of organic matter in soils, peat, and fossil-carbon-containing deposits is their decomposition degree, which describes their transformation intensity—the humification degree of original living organic matter. In this article approaches to the analysis of humification degree are thoroughly described and14C dated peat columns extracted from several bogs in Latvia are investigated and compared. A new humification indicator is suggested: the ratio of the total amount of organic matter in peat in respect to the amount of humic substances. Svarīgi augšņu, kūdras un fosilo oglekli saturošu nogulumu organiskās vielas raksturlielumi ir to sadalīšanās pakāpe, kas raksturo sākotnējās biomasas pārveidošanās intensitāti, un humifikācijas pakāpe, kas raksturo jaunu organisko vielu - humusvielu veidošanās tempu no sākotnējās dzīvās vielas. Šajā rakstā ir pētītas un salīdzinātas humifikācijas analīzes metodes pilnīgi analizētām un datētām (14C) kūdras kolonnām no vairākiem Latvijas purviem. Ieteikts humifikācijas pakāpi definēt kā kopējās organiskās vielas kūdrā un humifikācijas gaitā veidoto humusvielu attiecību.

Surface Activity of Humic Substances Within Peat Profile

Humic substances are able to reduce the surface tension of their solutions and thus can act as surface-active substances in natural environment and possibly also for industrial applications. The ability to influence the surface tension of humic substance solutions depends on their origin. The objective of this study is a comparison of the ability of humic substances from peat profile to influence the surface tension of their solutions and identification of the structural characteristics of peat humic acids, determining their surfactant properties. Humic acids isolated from peat demonstrated significant impact of the surface tension of their solutions – they act as weak surfactants. The surface tension of humic acid solutions decreased with increasing concentration, and it depends on the solution pH. The ability to influence the surface tension of peat humic acids isolated from a well-characterized bog profile demonstrates dependence on age and humification degree. With increase of the humification degree and age of humic acids, their molecular complexity and ability to influence surface tension decrease; even so, the impact of the biological precursor (peat-forming bryophytes and plants) can be identified.

Properties of the Jurassic Clayey Deposits of Southwestern Latvia and Northern Lithuania

Abstract Jurassic clay rich in organic matter from western Latvia is known already from early 19th century. Jurassic clays provide an interest because of high potential for innovative use due to its clay mineral composition jointly with organic material. Properties of the Jurassic clayey deposits were studied by using various physical and chemical methods. Material gained from field was tested by modern techniques such as UV-Vis, 3D fluorescence and FTIR - spectra, which show patterns of organic compounds in the clay material. AAS analyses characterized inorganic content. PXRD studies raised discussions about the origin of kaolin, illite and smectite and interactions among these clay minerals. Obtained results show that Jurassic clays with organic matter have future potential for possible use in cosmetic industry and as a sorbent material. Pētījumā gūtie rezultāti sniedz ziņas par Juras perioda mālaino nogulumu īpašībām, un palīdz salīdzināt šī perspektīvā derīgā izrakteņa īpašības. Juras sistēmas Kelovejas un Oksfordas stāvu nogulumi atrodami urbumu serdēs, atradnēs, kā arī pleistocēna ledāja atrauteņos jeb glasiodislokācijās. Līdz šim plašāki pētījumi notikuši Polijā un Lietuvā, salīdzinoši mazāk informācijas apkopots par Latvijas Juras māliem un to raksturojošām īpašībām. Šī pētījuma ietvaros paraugi tika ievākti Zoslēnu, Papiles un Lēģernieku atradnēs; to galvenās atšķirības saistās ar mālu frakcijas īpatsvaru salīdzinājumā ar pārējo nogulumu materiālu. Juras mālaino nogulumu sastāva īpatnības raksturotas, izmantojot granulometriskās analīzes, karsējuma zudumu, rentgendifraktometrisko un atomabsorbciometrijas metožu kompleksu; detalizēti pētīti arī nogulumu sastāvā esošie organiskie savienojumi, izmantojot UV-Vis un 3-D fluorescenci. Mālu sastāvā esošās organiskās vielas pamatā ir humusvielas, savukārt māla frakcijas neorganisko materiālu veido smektīts, illīts, kaolinīts un hlorīts aptuveni līdzīgās proporcijās, ko pierāda rentgendifraktometriskā izpēte. Agrākie pētījumi Polijā un Lietuvā liecina, ka dabiskās organiskās vielas, kas atrodamas Juras mālos, atspoguļo nogulumu veidošanās apstākļus. Juras māli var tikt izmantoti tālākos praktiskā pielietojuma pētījumos, kā arī, lai precīzāk raksturotu attiecīgā perioda paleoģeogrāfiskos apstākļus.

Peat humification character in two ombrotrophic bogs depending on peat properties

Peat humification character in two ombrotrophic bogs depending on peat properties Study of the living organic matter humification process is essential for understanding of the carbon biogeochemical cycle. The aim of this study is to determine the relations between peat properties and humification degree in two peat profiles in ombrotrophic bogs in Latvia, to identify the links between peat age, decomposition degree, peat properties, peat botanical composition and peat properties. The peat diagenesis process was described using multiproxy analysis of peat age, botanical composition, elemental composition, elemental ratios of the peat organic matter and peat alkaline extracts. This approach supports a better understanding of the peat properties and their relation both to peat decomposition processes, and also to original living organic matter. Multiproxy study of peat properties supports development of peat humification indicators. Kūdras humifikācijas rakstura atkarība no tās īpašībām divu augsto purvu kūdras kolonnas analīzes piemērā Oglekļa biogeoķīmiskās aprites cikla ietvaros notiekošo procesu izpētei svarīgi ir izprast dzīvās organiskās vielas pārvērtību raksturu, notiekot tās sadalīšanās - humifikācijas procesiem. Šī darba mērķis ir pētīt kūdras īpašības tās kolonnā atšķirīgas uzbūves augstā tipa purvos atkarībā no humifikācijas procesu rakstura, kā arī attīstīt risinājumus humifikācijas procesa raksturošanai. Pētījumā pierādīts, ka kūdras elementsastāva un īpašību analīze ļauj atsegt kopsakarības starp kūdras humifikācijas procesiem, kūdru veidojošo augu sastāvu un izstrādāt humifikācijas indeksus kūdras īpašību raksturošanai. Ieteikts humifikācijas pakāpes noteikšanai izmantot kopējās organiskās vielas kūdrā un humifikācijas gaitā veidoto humusvielu attiecību, kā arī kūdras sārmaina ekstrakta sorbcijas vērtību pie 540 nm.

Soil Pollution with Trace Elements in Territories of Military Grounds in Latvia

Soil Pollution with Trace Elements in Territories of Military Grounds in Latvia Contamination of land used for military activities can significantly differ from that of municipal and industrial land, both in the intensity and type. Largely this is due to the intensity of activities even in a comparatively large surface area, and also by use of substances and materials not common in civil practice. Pollution from military grounds can affect not only soldiers, but also adjacent territories and water resources. In this study, concentrations of trace elements in the soil, water and higher vegetation in former Soviet army military territories were surveyed. The presence of point sources was found, and in a few cases the pollution is intensively spreading into deeper soil horizons and groundwater. Militārajās teritorijās var būt vērojama vides mehāniskā degradācija, vides objektu lietojumveida izmaiņas, kā arī ķīmiskais piesārņojums, kas var skart ne tikai pašus militāros poligonus, bet arī blakus esošās teritorijas. Pētījuma ietvaros tika ievākti augsnes un augstākās vegetācijas paraugi Strautiņu un Šķēdes armijas poligonu teritorijās makro- un mikroelementu satura analīzēm. Analīžu rezultāti rāda, ka smago metālu koncentrācija apsekoto poligonu augsnēs, lai arī nav ekstremāli augsta, tomēr pārsniedz 2005. g. LR MK noteikumos Nr. 804 noteiktos mērķlielumus Zn, Pb, Ni, Cu, Cd saturam smilts augsnēs. Atsevišķu mikroelementu, piemēram, V, Sr, Y saturs augsnēs liecina par piesārņojuma avotu klātbūtni. Lai novērstu piesārņojošo vielu iedarbības iespējamās negatīvās sekas un ierobežotu piesārņojuma tālāku migrāciju, būtu nepieciešams veikt poligonu teritorijas rekultivāciju.

Characterization of Humic Acids from Raised Bog Peat

Abstract Humic substances form most of the organic component of soil, peat and natural waters, but their structure and properties are very much dependent on the source. The aim of this study was to characterize humic acids from raised bog peat to evaluate the homogeneity of humic acids isolated from the bog bodies and to study peat humification impact on the properties of humic acids. Peat humic acids (HA) have an intermediate position between the living organic matter and coal organic matter, with their structure formed in a process where the relatively labile moieties (carbohydrates, amino acids, etc.) are destroyed, and thermodynamically more stable aromatic and polycyclic structures emerge. Comparatively, the studied peat HAs were at the start of this transformation process. Concentrations of carboxyl and phenolic hydroxyl groups changed depending on the source depth of peat from which HAs were isolated. The carboxylic acidity of peat HAs increased with depth of the source and the extent of peat humification Kopsavilkums Veidojoties kūdras purvam, to skāruši dažādi klimatiskie apstākļi, hidroloģiskais režīms, tāpēc kūdras veidošanās apstākļi ir bijuši dažāda. Atkarībā no purvu veidojošās veģetācijas, mikroorganismu iedarbības un biomasas daudzuma palielināšanās radušās būtiskas izmaiņas kūdras humusvielās un to īpašībās. Šo īpašību raksturošanai izmantotas spektrālās metodes, kā arī elementsastāva un funkcionālo grupu analīze

Genesis of Peat Humic Acid Structure and Properties Within Bog Profiles

Studies of living organic matter humification process are essential for understanding of carbon biogeochemical cycle, and considering this, the aim of this study is to analyse relations between properties of the peat, peat humic acids (HAs) and humification degree on example of analysis of two bog profiles in ombrotrophic bogs to identify the links between peat age, decomposition and humification degree, botanical composition and properties of peat humic acids (elemental, functional composition). The found variability of peat properties is much less than the significant differences in properties of peat-forming living matter, thus stressing the dominant impact of humification process on peat properties. Correspondingly composition of peat humic acids are little affected by the differences in properties of precursor living organic material and indicators as decomposition degree, humification degree, humic acid elemental ratio and concentrations of acidic functional groups are best descriptors of changes of organic matter during humification process.