The Pantanal region is the largest floodplain area in the world and of great biological importance due to its unique flora and fauna. This area is continuously undergoing increasing anthropogenic threats, and has also experienced mercury contamination associated with gold mining and other anthropogenic activities. Pantanal caimans are top-level predators, and, as such, show great potential to accumulate mercury (Hg) by biomagnification. In this study 79 specimens from four locations in the Pantanal were analyzed for total Hg and methyl mercury (MeHg) by cold vapor atomic absorption spectrometry. Total Hg contents ranged from 0.02 to 0.36 µg g(-1) (ww), and most specimens presented MeHg ratios above 70%. One of the sites, impacted by anthropogenic activities, presented significantly higher total Hg in comparison to three less impacted sites, supporting the hypothesis that caimans can, in fact, be considered effective bioindicators of ecosystem health.

The Pantanal is one of the world's largest wetland ecosystems, encompassing 140,000 km 2 . The region is a breeding ground for waterfowl, and enormous rookeries of storks, herons, egrets, and ibises indicate a vast abundance of birds. The Pantanal is also one of the most important refuges for many of Brazil's threatened or endangered species, such as jaguars, giant anteaters, and swamp deer. The productive web of waters supports an important fishery industry. The Pantanal, with its extraordinary diversity and abundance of wildlife, is a threatened region. Deforestation, expanding agriculture, illegal hunting and fishing, unplanned tourism, and pollution with pesticides have caused a progressive deterioration of the natural environment, placing one of Brazil's most important ecosystems at risk. Gold mining is still common in the northern Pantanal. Along the Cuiabá river are 700 functional gold-mining dredges. In the town of Poconé, unregulated gold mines have also contaminated the area with mercury, which is used during the processing of gold. Approximately 50% of the fishes from the Cuiabá River and 35% from the Bento Gomes River have mercury levels higher than 0.5 g/g, which is beyond the international standard for contamination. Fishes from the Paraguay River have levels below 0.5. Birds like Phalacrocorax olivaceus, Aramus guarauna, and Rosthramus sociabilis were also contaminated. No research has been conducted on the fate of pesticides in the Pantanal. However, because of the huge demand for soybean plantations on the upland areas surrounding Pantanal, the application of toxic agricultural chemicals is very common.

210Pb results, the mercury content was determined for two sediment cores, showing that despite a constant concentration, the flux of Hg has increased due to an increase in the mass sedimentation rate. This increase can be attributed to the expansion of agricultural activity in the upper Taquari River during the last 25 years.

Abstract-The Pantanal is one of the world's largest wetland ecosystems, encompassing 140,000 km 2 . The region is a breeding ground for waterfowl, and enormous rookeries of storks, herons, egrets, and ibises indicate a vast abundance of birds. The Pantanal is also one of the most important refuges for many of Brazil's threatened or endangered species, such as jaguars, giant anteaters, and swamp deer. The productive web of waters supports an important fishery industry. The Pantanal, with its extraordinary diversity and abundance of wildlife, is a threatened region. Deforestation, expanding agriculture, illegal hunting and fishing, unplanned tourism, and pollution with pesticides have caused a progressive deterioration of the natural environment, placing one of Brazil's most important ecosystems at risk. Gold mining is still common in the northern Pantanal. Along the Cuiabá river are 700 functional gold-mining dredges. In the town of Poconé, unregulated gold mines have also contaminated the area with mercury, which is used during the processing of gold. Approximately 50% of the fishes from the Cuiabá River and 35% from the Bento Gomes River have mercury levels higher than 0.5 g/g, which is beyond the international standard for contamination. Fishes from the Paraguay River have levels below 0.5. Birds like Phalacrocorax olivaceus, Aramus guarauna, and Rosthramus sociabilis were also contaminated. No research has been conducted on the fate of pesticides in the Pantanal. However, because of the huge demand for soybean plantations on the upland areas surrounding Pantanal, the application of toxic agricultural chemicals is very common.

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Flood events are dependent on meteorological conditions but also depend on several other factors that are case specific, with relevance for reservoir operation. Hydrological and hydrodynamic models are valuable tools for understanding complex river hydrodynamics during flood events. These tools have been applied to improve understanding of the causes for an urban flood event that occurred between 9 and 11 January 2016 in the Mondego river basin, at Coimbra city (Portugal). Seven different factors that can, independently, influence the river flow at the study site were identified: three of them can be associated with the operational discharge schemes of the three upstream dams; two factors with the runoff flows from uncontrolled contributing sub-basins; another one related to discharge measurement uncertainty at a downstream dam; and finally, the seventh studied factor was sedimentation occurring in the main channel of the flooded river stretch.Hydroinformatic tools were applied in different scenarios allowing the characterization and identification of each one of the identified key factors responsible for the flood event. A proposal for a flood early warning system is presented based on the knowledge resulting from the studied flood event.

Hydrological and hydrodynamic models are valuable tools for understanding complex river hydrodynamics behavior during flood events. These tools have been applied to develop a detailed study of the flood event occurred between 9 and 11 January 2016 in the river Mondego basin, causing severe floods at Coimbra city (Portugal). The study included the characterization of the operational discharge schemes of three upstream dams with direct influence on flow rates in the river basin, and the runoff flows from contributing catchments. A detailed analysis on hydrodynamic water levels at the flooded areas influenced by the operation of a downstream dam and the local river morphodynamics was performed. Hydroinformatic tools were applied in different scenarios allowing the characterization and identification of the key factors responsible for the flood event and contributing to emphasize the need to comply with the established rules for the discharges at the upstream dams during flood events.