16 research outputs found
A comparative study of the properties of industrially produced humic substances
Humic substances (HSs) are produced industrially in large quantities from low rank
coal, weathered coal, peat, also from soils, composts and other sources. Considering that the
applications of industrially produced HSs also include food, pharmaceutical applications and
environmental technologies, it is important to evaluate their composition and quality and to
identify their sources. The aim of the present study is to compare the properties of industrially
produced HS samples. HSs were characterised using spectroscopic and other methods. For the
identification of origin of HSs, different methods can be used, such as elemental analysis and
ratios of light stable isotopes. The results of the study indicate that many industrially produced
HSs are of poor quality (low concentration of basic substance, admixture of undesirable
substances, pollutants, no quality indications). In this situation, rigorous quality control should
be implemented, providing detailed characteristics of the product. The composition of materials
suggested for agricultural applications has not been analysed much. Most of the studied materials
were designated as HAs, followed by fulvic acids (FAs) and HSs. However, an analysis of the
humic matter types indicates that the majority of substances offered on the market are in fact
mixtures of HAs and FAs; so, it would be more appropriate to designate them as HSs or their
salts. This study identifies the main quality problems of industrially produced humic substances:
1) lack of strict quality indicators, 2) absence of indication of source materials/origins of HSs
Impact of different fertilisers on elemental content in young hybrid aspen stem wood
The biomass production using fast-growing tree species such as hybrid aspen (Populus
tremuloides Michx. x Populus tremula L.) has been recognized as an environmentally friendly
and cost-effective approach. Growing these species can reduce the negative impact of earlier land
mismanagement and at the same time provide additional biomass growth. The application of
fertilisers may introduce not only the necessary macro elements (N, P, K) but also significant
amounts of toxic heavy metals. Therefore, the knowledge about elemental flows from fertilised
soil to the different parts of hybrid aspen trees is essential and especially meaningful for the
evaluation of element content in specific environmental ecosystems. The impact of different
fertilisers (sewage sludge, digestate and wood ash) on the concentrations of micro- and macro
elements in the wood of six-year-old hybrid aspen stands grown on former agricultural land was
studied. The determination of element concentrations in different tree rings of hybrid aspen trees
was accomplished by inductively coupled plasma mass spectrometry (ICPâMS). Isotope ratio
mass spectrometry (IRMS) was used to determine the nitrogen and carbon content and isotope
ratios in different parts of hybrid aspen trees. Stem disc samples from hybrid aspen trees were
obtained from agricultural land in the central part of Latvia. Samples were taken from six-yearold hybrid aspen trees that at the moment of planting were fertilised with sewage sludge, a residue
of biogas production (digestate) and wood ash. The obtained results indicated that the chemical
element accumulation in hybrid aspen was affected by the applied fertiliser type. In this study,
the use of wood ash, as well as digestate, affected the elemental content in hybrid aspen to a
greater extent than the use of sewage sludge, relative to unfertilised (control) subplot. The
analysed elements varied in the analysed stem plane (across the tree rings). The most significant
changes between the rings were observed for the content of K and Ca
The cosmological significance of Low Surface Brightness galaxies found in a deep blind neutral-hydrogen survey
We have placed limits on the cosmological significance of gas-rich low
surface-brightness (LSB) galaxies as a proportion of the total population of
gas-rich galaxies by carrying out a very deep survey (HIDEEP) for neutral
hydrogen (HI) with the Parkes multibeam system. Such a survey avoids the
surface-brightness selection effects that limit the usefulness of optical
surveys for finding LSB galaxies. To complement the HIDEEP survey we have
digitally stacked eight 1-hour R-band Tech Pan films from the UK Schmidt
Telescope covering 36 square degrees of the survey area to reach a very deep
isophotal limit of 26.5 R mag/sq. arcsec. At this level, we find that all of
the 129 HI sources within this area have optical counterparts and that 107 of
them can be identified with individual galaxies. We have used the properties of
the galaxies identified as the optical counterparts of the HI sources to
estimate the significance of LSB galaxies (defined to be those at least 1.5
magnitudes dimmer in effective surface-brightness than the peak in the observed
distribution seen in optical surveys). We calculate the contribution of LSB
galaxies to the total number, neutral hydrogen density, luminosity density,
baryonic mass density, dynamical mass density and cross-sectional area of
gas-rich galaxies. We do not find any `Crouching Giant' LSB galaxies such as
Malin 1, nor do we find a population of extremely low surface-brightness
galaxies not previously found by optical surveys. Such objects must either be
rare, gas-poor or outside the survey detection limits.Comment: 13 pages, 14 figures. Accepted for publication in MNRA
Burning of Fountain Candles IndoorâA Moment of Joy versus Indoor Air Quality Concerns
Burning candles, magic candles, incense, and pyrotechnics such as fountain candles creates a sense of joy and celebration in various life and social events [...
Multi-Element Profile Characterization of Monofloral and Polyfloral Honey from Latvia
Honey is of scientific interest mainly due to its health-promoting and antibacterial properties, which are also associated with its floral origins. However, the methods for confirming honey floral origins are quite limited and require improvements. One method suggested in the search for a multi-method approach to evaluating the floral origins of Latvian honey is inductively coupled plasma mass spectrometry (ICP-MS). This study investigated the multi-element profile of 83 honey samples of well-specified floral origins. The main findings included using Ba, Ca, Cs, Fe, and Rb as indicator elements for heather honey. The chemometric evaluation supported the use of ICP-MS for distinguishing heather honey from other types of honey. The Latvian polyfloral honey multi-element profile was defined and compared to honey samples with other geographical origins. Additionally, the multi-element profiles of buckwheat, clover, and polyfloral honey proteins were investigated to clarify whether the majority of elements were bound with proteins or not. Preliminary results indicated that Ca, K, Mg, Mn, Na, and Sr were mainly found in non-protein-bound forms, while the majority of Al, Cu, Ni, and Zn were in the form of large chemical structures (>10 kDa)
Multi-Element Profile Characterization in Monofloral Honey
Apiculture, in general, is an important sector of the national economy due to the environmental benefits of pollination [...
Caesium-133 Accumulation by Freshwater Macrophytes: Partitioning of Translocated Ions and Enzyme Activity in Plants and Microorganisms
The potential of aquatic plants to accumulate Cs may be of notable importance in the environmental monitoring of radioactive wastes. This study aimed to evaluate the accumulation of Cs-133 by freshwater macrophytes Bacopa amplexicaulis, Elodea densa, Ceratophyllum submersum, and Limnobium laevigantum after a 10-day incubation period with CsCl (1â1000 ÎŒM). The partitioning of Cs and other elements, including 21 metals, such as P, B, and As, was analyzed using inductively coupled plasma mass spectrometry combined with principal component analysis (PCA). The enzymatic activity of plant crude extracts and aquatic microorganisms was characterized. The transfer factor (TF) reached the highest values of 0.13 and 0.10 for C. submersum and L. laevigantum, respectively, at 1000 ÎŒM Cs. The TFs in the other sets were below 0.1. In the presence of Cs-133, there was a significant increase in dehydrogenase activity (p < 0.05) and a decrease in the activity of the FolinâCiocalteu assay. A three-fold decrease in culturable microorganisms was found in plants with 1000 ÎŒM Cs. PCA analysis revealed the species-specific elemental distribution in plant biomass and the aquatic phase. A negative correlation between Na, Ca (2.0â2.5, PC1) and Mg, K, and P (â2, PC1) was found. Certain enzyme groups can serve as bioindicators of Cs pollution in aquatic ecosystems
Impact of Wood Ash and Sewage Sludge on Elemental Content in Hybrid Alder Clone
In this study, the focus was on evaluating the effects of the initial treatment of wood ash and sewage sludge on hybrid alder clonesâ aboveground biomass and elemental content. To measure the element concentrations in the tree rings, laser ablationâinductively coupled plasmaâmass spectrometry (LA-ICP-MS) was utilized, which is a valuable tool for dendrochemistry research, albeit with some challenges in accurate quantification. One important aspect of the study was the development and comparison of different âin-houseâ matrix-matched standards for the precise quantification of element concentrations in tree rings. It was found that the commercially available reference materials, IAEA 413 (algae) and IAEA 392 (algae), were the best choices due to their homogeneity. The study also revealed that the use of sewage sludge and wood ash as soil improvers significantly benefited the increase in hybrid alder biomass. However, no significant increase in element content was found in the obtained wood mass, and for some elements, there was a decrease in concentration