Contracaecum sp. parasitizing Acestrorhynchus lacustris as a bioindicator for metal pollution in the Batalha River, southeast Brazil.

Pollution in aquatic ecosystems due to negative human activities remains a problem in both freshwater and marine environments and is an ongoing subject of research. Several studies have shown that some fish parasites can be used as a tool for biomonitoring because they demonstrate higher metal accumulation capacity compared to their host tissues. However, compared to acanthocephalans, information regarding the absorption mechanisms and accumulation rates in nematodes is relatively limited. Here, we evaluated the potential of larvae Contracaecum sp. (L3) as indicators of contamination by metals by analyzing thirteen element concentrations: magnesium (Mg), aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), barium (Ba), and lead (Pb) in the parasites and host Acestrorhynchus lacustris, using inductively coupled plasma mass spectrometry. Twelve of the thirteen analyzed elements were detected in at least 2-fold higher concentrations (e.g. Ni) and were up to approximately 50-fold higher (e.g. Pb) in parasites than in host tissues, including elements known for their high toxicity (As, Cd, Pb) and those considered to be essential (Cu and Zn). Our results suggest that Contracaecum sp. larvae can be used as bioindicators of metal contamination because even in early stages of development, numerous essential and non-essential elements were accumulated, making this system a useful tool for monitoring polluted environments.

Dating stalagmite from Caverna do Diabo (Devil´S Cave) by TL and EPR techniques.

A cylindrical fragment of stalagmite from Caverna do Diabo, State of São Paulo, Brazil, has been studied and dated by thermoluminescence and electron paramagnetic resonance techniques. The thermoluminescence glow curves of stalagmite samples and subsequently gamma irradiated, have shown rise of three peaks at 135, 180 and 265 °C. From electron paramagnetic resonance spectra of stalagmite was possible to clearly identify three paramagnetic centers in the g = 2.0 region: Centers I, II and III are due to , and , respectively. The additive method was applied to calculate the accumulated dose using thermoluminescence peak at 265 °C and the electron paramagnetic resonance signal at g = 1.9973 of CO- 2 radical. The ages of the different slices of stalagmite were determined from the Dac- values and Dan- value, obtaining an average of 86410 for central slice, 53421 for second slice, 31490 for third slice and 46390 years B.P. for the central region of upper end.