Elvis Joacir De França

Ni-Cr Alloy as Neutron Flux Monitor: Composition and Homogeneity Assessment by NAA

A Ni-Cr alloy was chosen as an in-house reference material for neutron flux measurement due to the well-known physical constants of the nuclides or interest and its low cost. The quantification of the Cr and Ni content was performed by neutron activation analysis (NAA), using certified reference materials from NIST as comparators. The concertrations and standard combined uncertainties were 19.32 ± 0.07 % for Cr and 80.2 ± 1.1 % for Ni, and the material is very homogeneous for Cr and moderate homogeneous for Ni.

Arsenic and trace metal contents in sediment profiles from the Admiralty Bay, King George Island, Antarctica

Admiralty Bay (Antarctica) hosts three scientific stations (Ferraz, Arctowski and Macchu Picchu), which require the use of fossil fuel as an energy source. Fossil fuels are also considered the main source of pollution in the area, representing important inputs of major pollutants (organic compounds) and trace metals and metalloids of environmental interest. Accordingly, this work presents the results of As, Cd, Cr, Cu, Ni, Pb and Zn in sediment profiles from Admiralty Bay. The sediment results from Ferraz station were slightly higher than the other sampling sites. The highest contents were observed for Cu and Zn (from 44 to 89 mg kg(-1)). Otherwise, by using enrichment factors and geochronology analysis, the most relevant enrichment was observed for As in the samples collected close to the Ferraz station, indicating that increasing As content may be associated with the activities associated with this site.

Seleção de epífitas acumuladoras de elementos químicos na Mata Atlântica

Epiphytes are efficient indicators of atmospheric pollution because of their direct uptake of chemical elements from atmosphere. Leaves from eleven species of bromeliads and one species of orchid were collected in the Parque Estadual Carlos Botelho, SP, for determination of sixteen chemical elements. The selection of the best biomonitor species was based on the diversity and accumulation of chemical elements in the leaves. With an average accumulation index of 0.7, Canistropsis billbergioides has potential to be used as a biomonitor of chemical elements in the Atlantic Forest.

Pathway of rare-earth elements in a Brazilian forestry fragment

The Mata de Santa Genebra is a fragment of semi-deciduous tropical forest located in an urban area of Sao Paulo State, Brazil. Potential sources of rare-earth elements (REE), such as oil refinery, agricultural activities and high-traffic roads, are situated close to this region. In this study, the central portion of the fragment dominated by Pachystroma longifolium and Esenbeckia leiocarpa was evaluated for the distribution of La, Ce, Nd, Sm, Eu, Tb and Yb in the soil, leaf and litter sub-compartments applying instrumental neutron activation analysis (INAA). Leaf/soil concentration ratios (CR) of P. longifolium were higher than those obtained for E. leiocarpa by a factor of 20. Considering leaf/litter concentration ratios, no retranslocation of these elements was noticed for both species before litterfall. Accumulation of REE and typical distribution patterns were observed for the plant sub-compartments. The high La content may be attributed to preferential uptake by these plants or to external atmospheric sources.

Survey of lanthanoids in plants from a tropical region

Several anthropogenic sources may provide lanthanoids (La, Ce, Nd, Sm, Eu, Tb and Yb) to the agricultural and forestry landscapes. Because little information is available on the distribution of these chemical elements in Brazilian tropical ecosystems, this work focuses on the survey in leaves of diverse plant species (native trees, epiphytes and crops) from different ecosystems. Soil under crown projection was also analysed, thereby estimating the influence of its chemical composition on accumulation in leaves. The degree of lanthanoids accumulation varied substantially even for species growing in the same habitat. The most accumulator species, Alsophila sternbergii, presented the typical distribution pattern for lanthanoids, different from Pachystroma longifolium, a native species from the urban fragment, and the cultivated Citrus sp., in which the altered patterns revealed lanthanum enrichment in spite of cerium depletion in the leaves.

Native plant bioaccumulation strategies: a baseline study for biomonitoring the Atlantic Forest

The atmosphere may act as an important source of chemical elements for the Atlantic Forest, one of the hottest world biodiversity hotspots. However, chemical responses for chemical element availability are not expected to be equal for each plant species. In this sense, the present work encompasses a baseline study for biomonitoring purposes based on the identification of different strategies of native tree species in accumulating chemical elements. Instrumental neutron activation analysis was employed for chemical characterisation of leaf and soil compartments. Results indicated a low level of pollution because the major part of the studied species has shown chemical mass fractions within the expected range in leaf compartment. By estimating leaf-soil bioaccumulation factor, some species were found to accumulate the nutrients Co, Na, Se and Zn, some trace elements Br, Ba, Cs, Hg, Rb, Sc and Sr and the lanthanides Ce, La and Sm despite the environmental variability.

Analytical quality in environmental studies: uncertainty evaluation of chemical concentrations determined by INAA

Instrumental neutron activation analysis (INAA) is a measurement technique of high metrological level for the determination of chemical elements. In the context of BIOTA/FAPESP Program, leaves of trees have been evaluated by INAA for biomonitoring purposes of the Atlantic Forest. To assure the comparability of results in environmental studies, a leaf sample of Marlierea tomentosa (Myrtaceae family) showing the lowest concentrations of chemical elements was selected for the evaluation of analytical quality of the determination under unfavorable conditions. Nevertheless, the homogeneity of chemical concentrations of sample at the 95% of confidence level has been achieved and INAA has presented repeatability of 2% for the determination of Br, Co, Cs, Fe, K, Na, Rb and Sr, the uncertainty could have been overestimated. For the evaluation of uncertainty due to the variability of chemical concentrations in the sample, Jackknife and Bootstrap methods were used to estimate the maximum expected percent standard deviation. The uncertainty budget was considered adequate for the reporting chemical concentrations of environmental samples determined by INAA.

Quality assessment in a Brazilian laboratory performing k0-NAA

This work is focused at the demonstration of the overall adequacy of the procedures introduced in a Brazilian laboratory for conducting the k0-standardized NAA. Concentrations of 29 elements determined in certified reference materials of plants and geological matrices are evaluated. Most of the experimentally determined values agreed well with the reference data and no consistent bias could be attributed to the analytical system adopted.

Enrichment diagram (ED) : A graphic approach for assessing inorganic enrichment and contamination in marine sediments of Sepetiba Bay (SE Brazil)

Purpose – The purpose of this paper is to validate and apply enrichment diagrams (EDs) to determine metal and as enrichment and contamination in the sediments of Sepetiba Bay. Design/methodology/approach – Through inducted coupled plasma – optical emission spectrophotometry, total element (As, Cd, Cu, Ni, Pb and Zn) concentrations were assessed for the construction of EDs and comparison with enrichment factors (EFs) in 65 samples collected in Sepetiba Bay. Findings – Based on the EDs, it was observed that the sediments around the urban area of Sepetiba and ItaguaiHarbor were contaminated with Cd, Cu, Ni, Pb and Zn. These contaminants were expected due to the urban and industrial discharges into the bay and the activities at ItaguaiHarbor. Originality/value – The ED was successful regarding its ability to evaluate inorganic contamination in Sepetiba Bay. In addition, this method was able to define a proper background sample for calculating EFs.

Atmospheric chemical element pollution in an urban water-associated environment

Nowadays, sustainability has become a complicated issue mainly in urban centres. Owing to the atmospheric emissions, the incorporation of toxic chemical elements is still not well known for urban water-associated ecosystems. Tillandsia bromeliads were employed as passive biomonitors of air pollution. Otherwise, the tank bromeliad Canistropsis billbergioides, native to the Atlantic Forest, was employed for assessing pollution levels since the tank, unlike atmospheric epiphytes, also accumulates chemical elements from water and litterfall. The present study aimed at using leaves of the native epiphytic bromeliads (passive biomonitoring) from riparian areas and the species C. billbergioides (active) to evaluate the atmospheric input of chemical elements for wet ecosystems from the Piracicaba City, Sao Paulo State, Brazil. Chemical elements determined by Instrumental Neutron Activation Analysis (INAA), such as As, Cr, Hg, Ni, Sb and Zn, were accumulated in leaves of bromeliads. By combining passive and active experimental designs, hotspots for chemical atmospheric pollution were identified in the Piracicaba River Basin.