12 research outputs found
Application of mineralogical, petrological and geochemical tools for evaluating the palaeohdrogeological evolution of the PADAMOT study sites
The role of Work Package (WP) 2 of the PADAMOT project – ‘Palaeohydrogeological Data
Measurements’ - has been to study late-stage fracture mineral and water samples from
groundwater systems in Spain, Sweden, United Kingdom and the Czech Republic, with the aim
of understanding the recent palaeohydrogeological evolution of these groundwater systems. In
particular, the project sought to develop and evaluate methods for obtaining information about
past groundwater evolution during the Quaternary (about the last 2 million years) by examining
how the late-stage mineralization might record mineralogical, petrographical and geochemical
evidence of how the groundwater system may have responded to past geological and
climatological changes.
Fracture-flow groundwater systems at six European sites were studied:
• Melechov Hill, in the Bohemian Massif of the Czech Republic: a shallow (0-100 m)
dilute groundwater flow system within the near-surface weathering zone in fractured
granitic rocks;
• Cloud Hill, in the English Midlands: a (~100 m) shallow dilute groundwater flow system
in fractured and dolomitized Carboniferous limestone;
• Los Ratones, in southwest Spain: an intermediate depth (0-500 m) dilute groundwater
flow system in fractured granitic rocks;
• Laxemar, in southeast Sweden: a deep (0-1000 m) groundwater flow system in fractured
granitic rocks. This is a complex groundwater system with potential recharge and
flushing by glacial, marine, lacustrine and freshwater during the Quaternary;
• Sellafield, northwest England: a deep (0-2000 m) groundwater flow system in fractured
Ordovician low-grade metamorphosed volcaniclastic rocks and discontinuous
Carboniferous Limestone, overlain by a Permo-Triassic sedimentary sequence with
fracture and matrix porosity. This is a complex coastal groundwater system with deep
hypersaline sedimentary basinal brines, and deep saline groundwaters in crystalline
basement rocks, overlain by a shallow freshwater aquifer system. The site was glaciated
several times during the Quaternary and may have been affected by recharge from glacial
meltwater;
• Dounreay, northeast Scotland: a deep (0-1400 m) groundwater flow system in fractured
Precambrian crystalline basement overlain by fractured Devonian sedimentary rocks.
This is within the coastal discharge area of a complex groundwater system, comprising
deep saline groundwater hosted in crystalline basement, overlain by a fracture-controlled
freshwater sedimentary aquifer system. Like Sellafield, this area experienced glaciation
and may potentially record the impact of glacial meltwater recharge.
In addition, a study has been made of two Quaternary sedimentary sequences in Andalusia in
southeastern Spain to provide a basis of estimating the palaeoclimatic history of the region that
could be used in any reconstruction of the palaeoclimatic history at the Los Ratones site:
• The Cúllar-Baza lacustrine sequence records information about precipitation and
palaeotemperature regimes, derived largely from the analysis of the stable isotope (δ18O
and δ13C) signatures from biogenic calcite (ostracod shells).
• The Padul Peat Bog sequence provided information on past vegetation cover and
palaeogroundwater inputs based on the study of fossil pollen and biomarkers as proxies
for past climate change.
Following on from the earlier EC 4th Framework EQUIP project, the focus of the PADAMOT
studies has been on calcite mineralization. Calcite has been identified as a late stage mineral, closely associated with hydraulically-conductive fractures in the present-day groundwater
systems at the Äspö-Laxemar, Sellafield, Dounreay and Cloud Hill sites. At Los Ratones and
Melechov sites late-stage mineralization is either absent or extremely scarce, and both the
quantity and fine crystal size of any late-stage fracture mineralization relevant to Quaternary
palaeohydrogeological investigations is difficult to work with. The results from the material
investigated during the PADAMOT studies indicate that the fracture fillings at these sites are
related to hydrothermal activity, and so do not have direct relevance as Quaternary indicators.
Neoformed calcite has not been found at these two sites at the present depth of the investigations.
Furthermore, the HCO3
- concentration in all the Los Ratones groundwaters is mainly controlled
by complex carbonate dissolution. The carbonate mineral saturation indices do not indicate
precipitation conditions, and this is consistent with the fact that neoformed calcite, ankerite or
dolomite have not been observed petrographically
Proposal of a suitable insurable portfolio for a municipality Budišov
Diplomová práce se zabývá problematikou, která souvisí s návrhem pojistného portfolia pro obec Budišov. Na základě aktiv obce a analýzy rizik je navrhnuto takové pojistné portfolio, díky kterému budou nejzávažnější rizika obce prostřednictvím komerční pojišťovny minimalizována.This diploma thesis deals with the problems related to insurance protection for municipality Budišov. The insurance portfolio is suggested on the basis of municipality assets and analysis of all risks. It helps to minimize the most serious risks of its activities through the commercial insurance company.
Unusual mixed silica–carbonate deposits from magmatic–hydrothermal hot springs, Savo, Solomon Islands
Kinetic study of time-dependent fixation of UVI on biochar
Biochar, a by-product from the production of biofuel and syngas by gasification, was tested as a material for adsorption and fixation of UVI from aqueous solutions. A batch experiment was conducted to study the factors that influence the adsorption and time-dependent fixation on biochar at 20oC, including pH, initial concentration of UVI and contact time. Uranium (UVI) adsorption was highly dependent on pH but adsorption on biochar was high over a wide range of pH values, from 4.5 to 9.0, and adsorption strength was time-dependent over several days. The experimental data for pH > 7 were most effectively modelled using a Freundlich adsorption isotherm coupled to a reversible first order kinetic equation to describe the time-dependent fixation of UVI within the biochar structure. Desorption experiments showed that UVI was only sparingly desorbable from the biochar with time and isotopic dilution with 233UVI confirmed the low, or time-dependent, lability of adsorbed 238UVI. Below pH 7 the adsorption isotherm trend suggested precipitation, rather than true adsorption, may occur. However, across all pH values (4.5–9) measured saturation indices suggested precipitation was possible: autunite below pH 6.5 and either swartzite, liebigite or bayleyite above pH 6.5
The distribution of depleted uranium contamination in Colonie, NY, USA
Uranium oxide particles were dispersed into the environment from a factory in Colonie (NY, USA) by prevailing winds during the 1960’s and ’70’s. Uranium concentrations and isotope ratios from bulk soil samples have been accurately measured using inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) without the need for analyte separation chemistry. The natural range of uranium concentrations in the Colonie soils has been estimated as 0.7 – 2.1 μg g-1, with a weighted geometric mean of 1.05 ± 0.06 μg g 1; the contaminated soil samples comprise uranium up to 500 ± 40 μg g-1. A plot of 236U/238U against 235U/238U isotopes ratios describes a mixing line between natural uranium and depleted uranium (DU) in bulk soil samples; scatter from this line can be accounted for by heterogeneity in the DU particulate. The end-member of DU compositions aggregated in these bulk samples comprises (2.05 ± 0.06) x10-3 235U/238U, (3.2 ± 0.1) x10-5 236U/238U, and (7.1 ± 0.3) x10-6 234U/238U. The analytical method is sensitive to as little as 50 ng g-1 DU mixed with the natural uranium occurring in these soils. The contamination footprint has been mapped northward from site, and at least one third of the uranium in a soil sample from the surface 5 cm, collected 5.1 km NNW of the site, is DU. The distribution of contamination within the surface soil horizon follows a trend of exponential decrease with depth, which can be approximated by a simple diffusion model. Bioturbation by earthworms can account for dispersal of contaminant from the soil surface, in the form of primary uranium oxide particulates, and uranyl species that are adsorbed to organic matter. Considering this distribution, the total mass of uranium contamination emitted from the factory is estimated to be c. 4.8 tonnes
Assessment of trace elements in the shell layers and soft tissues of the pearl oyster Pinctada radiata using multivariate analyses: a potential proxy for temporal and spatial variations of trace elements
Concentrations of trace elements (Cd, Cu, Ni, Pb, V, and Zn) were determined in the soft tissues (adductor muscle and gills) of the pearl oyster Pinctada radiata and surficial sediments from two sampling sites located in the northern part of the Persian Gulf by Graphite Furnace Atomic Absorption Spectrophotometer (GFAAS). Moreover, the levels of Li, Mg, Al, Mn, Fe, Cu, Sr, Ba, Pb, and Zn were measured in two shell layers (prismatic and nacreous) using Laser Ablation Inductively Coupled Plasma Mass Spectrometer (LA-ICP-MS). There were significant differences between the sampling sites with regard to mean concentrations of Cu, Mn, and Al in the prismatic layers of the shells. But in terms of the soft tissues, only in the case of Ni accumulation in the muscle significant differences between the sites could be observed. No significant differences could be found between the sites from the elements concentrations in the sediments point of view. The levels of Cd, Cu, Ni, and Zn in the gills were markedly higher than those in the muscle. Concentrations of Mn, Mg, Li, and Cu in the prismatic layer were significantly higher than in the nacreous but the reverse case could be found for Sr. The patterns of metal occurrence in the selected tissues, shell layers, and sediments exhibited the following descending order: Zn, Ni > Cd, Cu > V, and Pb and Zn, Ni, Cd > Cu, V, and Pb for muscle and gills, respectively; Zn > Cu, Ni, Pb, Cd, and V for sediments; Mg > Sr, Mn, Li, Al, Fe, Ba, Cu, Pb, and Zn for the prismatic layer; and Sr, Mg > Mn, Al, Fe, Li, Ba, Cu, Pb, and Zn for the nacreous layer. In most cases, the temporal variations of the elements levels in the prismatic layer were clearer than those in the nacreous layer (especially for Li, Mg, Mn, Pb, and Fe). Comparison of the gained data from this study with the other relevant researches shows that in most cases the levels of the elements in this investigation either fell within the range for other world areas or were lower. Generally, it can be concluded that the shell (especially prismatic layer) of P. radiata can be considered as a suitable proxy for temporal and spatial variations of the trace elements (and probably some environmental parameters) in the study are
Uranium anomalies identified using G-BASE data - natural or anthropogenic? A uranium isotope pilot study
The rapid quantitative analysis by inductively coupled plasma quadrupole mass spectrometry
(ICP-QMS) for uranium isotope ratios has been successfully established and tested. The method
is fully documented in this report.
The rapid and cost effective nature of the methodology has allowed the analysis of a selection of
G-BASE soil and stream sediment archive material to be undertaken, which was not possible
previously. These samples were chosen by careful consideration of the findings of previously
published G-BASE atlases. During the course of mapping Britain, the G-BASE project has
encountered anomalously high concentrations of uranium in several areas, in comparison to the
regional background values. Samples from regions believed to be enhanced in uranium due to
natural processes alone were chosen to allow the variability of uranium isotope ratios to be
quantified, and hence provide an isotopic baseline. Samples which had been recognised during
geochemical baseline mapping as having anomalously high uranium concentrations in the locale
of nuclear fuel installations were also selected for comparison with this isotopic baseline.
As would be expected from literature values, the 238/235U ratio was constant in all the natural
enhanced samples, whilst some variation in 238/234U was observed. This was also the case for
samples from the urban industrial fringes of Greater Merseyside, which had high concentrations
of heavy metal contaminants. In contrast, all samples associated, by proximity, with nuclear fuel
facilities were found to have isotope ratios reflecting a contribution from enriched uranium.
These results are consistent with the limited suite of RIFE (Radioactivity in Food and the
Environment) data available, but are of better precision.
Difficulties exist in quantifying the contribution of processing facility uranium to stream
sediments and soils, due to the limited information available on the likely composition of the
original materials entering the stream course, or soil profile. These factors are highlighted, along
with possible further investigations to elucidate dissemination of anthropogenic uranium in the
environment
The effect of environmental factors on shell growth and repair in Buccinum undatum
The processes and factors which affect shell growth and repair in molluscs are poorly understood. In this study, the capabilities of shell growth and repair in the marine gastropod Buccinum undatum were investigated experimentally by implementing laboratory-controlled mechanical damage to the shell margin/lip. Three key factors, life stage (juvenile or adult), seawater temperature (5–15 °C) and food availability (unfed, weekly, or daily feeding), were investigated in a series of controlled laboratory experiments to establish their roles in the processes of shell growth and repair. Significant differences in rates of shell growth and repair between food and temperature regimes were observed, with the greatest difference occurring with different life stages. Rates of shell growth in non-damaged whelks were slightly faster but not significantly different from damaged individuals in any of the experiments. Tank-reared juveniles maintained in the highest seawater temperature regime (15 °C) displayed significantly faster rates of shell repair (F = 6.47, p < 0.05) than conspecifics held at lower seawater temperatures. Through characterising both biological and environmental factors affecting shell growth and repair, it is demonstrated that there are multiple aspects influencing shell growth and shell repair. It is important to be able to understand and establish differences in rates of growth to better manage this commercial species
Elemental composition of aquaculture fish from West Bengal, India: nutrition versus food safety
Aquaculture production continues to grow in West Bengal, where on average people consume 8.2 kg capita−1 of fish each year, and an extensive mosaic of aquaculture ponds has developed along the River Hugli as clay pits are repurposed. The adjacent brickworks and industry (especially tanneries) are a source of environmental pollution, with potential for bioaccumulation of potentially harmful elements (PHEs) in fish farmed in these ponds. Fish from aquaculture present an opportunity to meet food sufficiency in West Bengal; however, an investigation to assess their effectiveness for micronutrient supply balanced against food safety is required. Five ponds close to industrial brick manufacture (urban) and three from rural areas were assessed for the degree of pollution within their pond sediments and waters. Fish were also sampled from each location including a subset from the market in Kolkata to determine the concentrations of PHEs in their fish muscle tissue. Dietary intake and PHE loading were calculated for four fish species to evaluate their nutrient content with respect to recommended daily intakes for adults, e.g. calcium (Ca), potassium (K), magnesium (Mg), iron (Fe), zinc (Zn) and selenium (Se), and to establish whether the provisional maximum tolerable intakes (PMTIs) are exceeded for PHEs, e.g. aluminium (Al), arsenic (As), mercury (Hg), chromium (Cr), tin (Sn), copper (Cu) and lead (Pb). Preliminary results suggest that aquaculture is making an important contribution to nutrition, with fish being a good source of Se. However, in contrast to small wild-caught fish, aquaculture fish in the present study were poor sources of Fe, Ca and Zn. The fish also made substantial contributions (> 10%) to the PMTI of Hg and As. Therefore, there is an urgent need for ongoing monitoring and an expanded sampling programme, as well as research into approaches which might improve the nutritional quality of the farmed fish