A. V. B. Bellido

Classificação de cerâmicas arqueológicas da Bacia Amazônica

In order to elucidate the traditional classification of archaeological artefacts, a multielemental analytical method for characterisation of its micro and macro chemical constituents. combined with statistical multivariate analysis for classification, were used. Instrumental thermal neutron activation analysis, for elemental chemical determination, and three statistical methods: discriminant, cluster and modified cluster analysis were applied. The statistical results obtained for the samples from Iquiri, Quinari and Xapuri archaeological phases were in good agreement with the conventional archaeological classification. Iaco and Jacuru archaeological phase were not characterised as homogenous groups. Iquiri phase were the most distinct in relation to the other analysed groups. An homogeneous group for 54% collected samples at the Los Angeles site was also found, this could be characterised as a new archaeological phase.

Concentration of airbone trace metals in a bus station with a high heavy-duty diesel fraction

Amostras de material particulado total (MPT) e MP10 foram coletadas numa estacao de onibus, no periodo de agosto de 2006 a fevereiro de 2007. Na area, as unicas fontes importantes de emissao de poluentes sao os onibus, ja que os veiculos leves representam apenas 1-2% do fluxo total e nao sao desenvolvidas outras atividades no local. As concentracoes de metais foram determinadas por espectroscopia de emissao por plasma indutivamente acoplado (ICP-OES). Os metais mais abundantes foram Ca, Mg, Fe e Al, que correspondem a 50,1%; 24,2%; 6,5% e 18,7%, respectivamente, do conteudo metalico. O Co, Ni, Cd, Cr e Pb foram encontrados em niveis inferiores ao seu limite de deteccao, exceto para algumas poucas amostras. Os fatores de enriquecimento calculados, mostram que o Zn e o Cu sao devidos provavelmente a composicao do combustivel e do oleo lubrificante. O Ca, Mg e Al podem ser atribuidos a resuspensao de poeira, enquanto que o Fe pode ser devido tanto a ressuspensao de poeira como as emissoes dos veiculos.

Influence of biological activity on 65 Zn and 109 Cd removal from tidal water by chronically-polluted mangrove sediments

The biological activity influence on the mangrove sediment capacity to remove 65Zn and 109Cd from tidal water was evaluated in a site chronically polluted. Benthic Activity Indexes (BAI), corresponding to relative estimates of biological impact on radiotracer accumulation, were higher for 109Cd (~ 38%) than for 65Zn (~ 10%) in the top centimetre of sediment. However, BAI exceeded 96% for deeper sediment layers. This apparent decrease in radiotracer diffusion into deep sediments through biological activity inhibition is stronger than reported for much less polluted mangrove nearby, suggesting that benthic organisms tolerant of chronic metal pollution may affect metal sorption mechanisms.

Radiotracers as a Tool to Elucidate Trace Element Behaviour in the Water–Sediment Interface

Behavioural trends of trace elements in the water–sediment interface of diverse aquatic systems have been elucidated by using radiotracer experiments. These experimental data have improved: (1) the comprehension on the biogeochemical mechanisms, (2) estimations of amounts and kinetics of the transfers across the interface and (3) the characterisation of the role of sediments as sinks for the studied elements. Many efforts have been found in the scientific literature through the use of radiotracers to evaluate the role of biological activity (mainly by bioturbation) in determining trace element behaviour, evidencing that this activity can be a major factor of influence on trace element exchanges across water–sediment interfaces. Moreover, biogeochemical studies with radiotracers definitely help in elucidating mechanisms, pathways, bioavailability and uptake by aquatic organisms. Furthermore, radiotracer percolation experiments within upper layers of sediments are strongly recommended for intertidal ecosystems, since vertical tidal variability must be taken into account, besides conventional diffusion-based approach. Nevertheless, there is still a lack of data on the role of chemical speciation in such studies. Such behavioural aspects of chemical speciation deserve further attention in order to improve: predictions on environmental risk assessment for toxic elements, evaluations of the applicability and suitability of potential biological monitors for trace element contamination and predictions on trace element speciation and bioavailability sensitivity due to global environmental changes.