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Abstract Mercury pollution of water bodies exerts significant human and ecosystem health impacts due to high toxicity. Relatively high levels of mercury have been detected in the Amazon River and its tributaries and associated lakes. The study employed a Bayesian Network approach to investigate the contribution from geogenic sources to mercury pollution of lakes in the Madeira River basin, which is the largest tributary of the Amazon River. It was found that the source indicators of naturally occurring mercury have both, positive and negative relationships with mercury in lake sediments. Although the positive relationships indicated the influence of geological and soil formations, the negative relationships implied that the use of mercury amalgam for gold extraction in artisanal and small-scale mining (ASM), which is the primary anthropogenic source of mercury, also contribute to mercury in Amazon tributaries. This was further evident as mercury concentrations in lake sediments were found to be significantly higher than those in the surrounding rocks. However, potential anthropogenic mercury was attributed to historical inputs from gold mining due to the recent decline of ASM mining practice in the region. Graphical abstract fx1 Highlights • Hg pollution of lakes in the largest Amazon River basin was characterised. • Geochemistry of Amazon tributaries influences Hg pollution of lake sediments. • Historical inputs of Hg from gold mining still pose risks to the ecosystem. • Need for strict regulation of artisanal and small-scale gold mining emphasized. [ABSTRACT FROM AUTHOR]

Birds harbor an astonishing diversity of haemosporidian parasites belonging to the genera Haemoproteus, Leucocytozoon, and Plasmodium. Currently there are more than 250 morphologically described avian haemosporidian species and 2,828 unique lineages found in virtually all avian clades and zoogeographic regions, except for Antarctica. Our report is based on PCR and microscopic screening of 1,302 individual avian samples from Brazil to detect the underrepresented genus Leucocytozoon. This survey primarily focuses on passerine birds collected from Amazonia, the Atlantic Rain Forest, and Pantanal. We also summarize studies conducted in Brazil that report haemosporidian prevalence using both microscopy and molecular tools and present for the first time a record of Leucocytozoon infecting an avian host population in Amazonia. Based on our findings, we suggest that high average temperatures may be constraining both the distribution and diversity of Leucocytozoon in lowland tropical South America. [ABSTRACT FROM AUTHOR]