Few dedicated attempts at comparing the monitoring performance of lower and higher plants have been carried out so far. As a contribution to such an issue, this paper looks into the relative magnitude of elemental signals from epiphytic lichens (Parmelia spp.) and olive tree (Olea europaea Linn.) bark, determined by INAA. A representative set of 12 elements - As, Ba, Br, Ca, Cl, K, Mg, Mn, Na, Sr, V, Zn - was used for an ab initio comparison between raw data and Rb-normalized data, using distribution-free statistics. Correlation analysis shows an overall improvement in the degree of association between bark and lichen signals when proceeding from raw data to relative enrichment. Apart from Cl, no element is enriched in lichens to a higher extent than in bark. Sign tests are quite conclusive: bark factors are either statistically greater than or equal to lichens'. These findings prompt a word of caution when dealing with biological monitoring data, without accounting for soil, rock or litter inputs into the biomonitors' elemental pools.
Authors:J. Gbadago, A. Faanhof, C. Schandorf, and E. Darko
The effectiveness of the neutralization process on heavy metals precipitated in sludge has been evaluated using instrumental
neutron activation analysis (INAA) facilities at the South African Nuclear Energy Corporation (Necsa). The elemental concentrations
of Th, Fe, Ag, Co, Cr, As, Au and K were reduced after the neutralization process with the exception of Mn and Sn which appeared
to be enhanced by the neutralization process. Even though the neutralization process was targeted at the basic ferric arsenate
compound, it was found to be effective in reducing other elemental concentrations. The variations in the geochemical compositions
of the sulphidic ores during treatment at various stages also showed that physical processing stages do not significantly
alter the elemental concentrations in the feed materials, however, the chemically active processing stages do. Also, the enhancement
of the elements at the chemical stages depends on total quality control, where the application was not very repeatable the
pattern of variation of elements at some stages was found to be irregular irrespective of the ore grade. The elements; Sn,
Fe, Th, K, Au, Ag, As, Cr, and Co were enhanced in almost all the chemically active stages. Au was much more enhanced during
flotation and bio-oxidation processes. Correlation analysis performed to determine the distribution patterns show that Fe,
As, Ag and Co are geochemically associated and might be enriched simultaneously.
Crystallisation is generally regarded as a nucleation — growth mechanism of a solid phase and often studied using thermo chemical
methods. The present work postulates an analogy to melting processes, looking at melting as nucleation — growth of a liquid
phase. The melting process of acetylsalicylic acid single crystals was investigated by DSC measurements under isothermal conditions.
The fraction of material molten after a certain time period, α(t), was calculated by integrating the DSC curves. The resulting kinetic curves were fitted using the Avrami-Erofeev equation:
–ln(1–α)=ktn, where parameter n was analysed. According to established methods, functions I('2')=[t('2')]/[t('2')+t('3')]100% and I('3')=[t('3')]/[t('3')+t('2')]100% were introduced, where t('2') and t('3') is the absolute time of consumption two- and three-dimension nuclei growth, respectively. Applying correlation analysis,
relationships between two- or three-dimensional growth and the independent variables describing the single crystals (for strictly
definite trajectories into the space of sizes) were found. Particular correlations were:a) Two-dimensional growth is a function
of the total surface area of the crystal, S, and of the surface area of the (ac)-face, Sac; b) Three-dimensional growth is a function of S/M (where M is the mass of the single crystal). It is also a function of Sac/M and of S. The obtained experimental data are explained by the ‘layer’ structure of crystals of acetylsalicylic acid.
Authors:Bogdan Skwarzec, Krzysztof Kabat, Tomasz Puzyn, and Aleksander Astel
The study deals with the application of cluster analysis (CA) and non-parametric tests (Shapiro–Wilk, Kruskal–Wallis, Dunn,
U Mann–Whitney) to classify and interpret of a monitoring data set for Odra River water quality assessment based on concentration
values of radiochemical parameters. The data set represents results for 3 alpha emitters (210Po, 238U and 239+240Pu) measured in surface water samples collected at 13 different sampling locations (5 in major Odra stream while 8 in Odra
tributaries) within four seasons: winter, spring, summer and autumn, in the framework of 1 year-term quality monitoring research.
The correlation analysis of polonium, uranium and plutonium data indicates that significant values of Spearman’s correlation
coefficient appears between 210Po and 239+240Pu (r = 0.55 in autumn and 0.77 in winter as well as 0.49 in all year), while statistical significant correlation between uranium
and plutonium as well as uranium and polonium were not found. In the Odra drainage basin, the biggest differences were observed
in the case of 238U. The hypothesis about possible geographic and seasonal differences between concentration of 210Po, 238U and 239+240Pu in the Odra River catchment area was verified by cluster analysis (CA). Finally, to asses if there are statistically significant
differences in mean concentration value of 210Po, 238U and 239+240Pu for Vistula and Odra Rivers drainage basins were obtained by used of the non-parametric tests. Comparing to Vistula catchment
area, statistically different concentration of 210Po and 239+240Pu in all year was observed for river samples collected on Odra drainage basin.
Authors:Zhongyu Wu, K. Inn, Zhichao Lin, and C. McMahon
One of the most critical elements of a performance evaluation (PE) program for radioactivity measurements is the traceability of the PE materials to the national standards. The requirements and criteria for the production of traceable environmental and radiobioassay PE materials have been defined by ANSI N42.22 and ANSI N13.30 standards. It is important to note that use of traceable source materials does not necessarily ensure the traceability of subsequently derived PE materials unless verification measurements exist in conjunction with the preparation processes. This paper describes the protocol currently used by NIST for the preparation and verification of air filter, acidified water, spiked soil, synthetic urine, and synthetic fecal PE materials for low-level radioactivity measurements. The process involves gravimetric dilutions and mixing of primary radionuclide NIST Standard Reference Materials (SRMs), addition of the derived master solution to sample matrices, and subsequent verification measurements. Several gamma-emitters were used to trace the gravimetric dilutions and spike addition through an unbroken chain of gamma comparison measurements. The massic activities of alpha- and beta-emitters in the diluted solutions and PE samples were also measured by radiochemical methods and compared with their gravimetric values. A correlation analysis demonstrated that the gamma emitters quantitatively followed 90Sr, 238U, 238Pu, and 241Am throughout the dilution and spiking and can be used as effective process monitors. The statistical results from t-tests, box plots, and normal probability tests suggested that traceability of radionuclides in the PE materials to their primary standards can be verified to within 1%, with an overall precision better than 2% (1s).