Flood pulse as a driving force of Pb variation in four fish guilds from Puruzinho Lake (western Amazon).

The Brazilian Amazon is heavily impacted by mining activities, especially by gold and cassiterite mining. Pb is a contaminant released during cassiterite extraction, and it stands out for its high toxicity. The present study aimed to evaluate the effect of flood pulse on Pb dynamics in four fish species with different feeding habits (Cichlapleiozona: carnivorous, Mylossomaduriventre: herbivorous, Prochilodus nigricans: detritivorous, and Serrasalmus rhombeus: piscivorous) over four hydrological periods in Puruzinho Lake (Brazilian Amazon), which receives water from the Madeira River. The risk assessment for daily Pb intake through the consumption of these fish by the local riverside population was also carried out. Fish species were sampled during four Amazonian hydrological periods: rising water, high water, falling water, and low water. Pb and stable isotopes (δ15N and δ13C) measurements were carried out on fish muscle. The flood pulse had the same effect on Pb concentrations of all the fish species regardless of their feeding habits, as we found a nonsignificant interaction between these variables. The Pb in fish muscle increased in the flood season (rising and high water) and decreased in the dry season (falling and low water). The Pb concentration in fish increased significantly with their trophic level (δ15N), evidencing the occurrence of biomagnification of the element along the trophic chain (R2 = 0.24). The main food source of the herbivorous fish (δ13C) was very distinct from that of the others, which had a large overlap in their values. Regarding risk assessment, the daily Pb intake through consumption of the herbivorous species during high water (17.82 ± 19.68 µg∙day-1) exceeded the limit determined by the Food and Drug Administration (FDA) of 12.5 µg∙day-1, representing a health risk to the riverside population of Puruzinho Lake.

Spatial-temporal dynamics of Cr in fish from Puruzinho Lake (Western Amazon) and dietary risk assessment.

Cr contamination is a growing concern in the Amazon. Along with the rise of cattle farming in the region, tanneries are becoming more common and threatening environmental quality, since the effluents from this activity are rich in Cr. The objective of this study was to evaluate the seasonal and spatial dynamics of Cr in fish with different feeding habits from Puruzinho Lake, located in the Madeira River basin, also determining the daily intake of Cr associated with the consumption of these fish by the population that lives around the lake. Seasonality and feeding habits directly affected Cr dynamics in fish (p < 0.0001), with medians of Cr concentration ranging between 0.07 mg kg-1 in the species Cichla pleiozona, a carnivorous fish, and 0.62 mg kg-1 in Mylossoma duriventre, a herbivorous fish. The high Cr concentrations in M. duriventre were related to the biodilution effect of Cr in the trophic chain (R2 = 0.14, p < 0.0001). The consumption of M. duriventre by the population was associated with the highest daily intake of Cr (55.5 µg∙day-1), exceeding the recommended limits of Cr intake (35 µg∙day-1). However, no harmful effects on health are expected due to the ingestion of Cr through the consumption of fish from Puruzinho Lake. Spatial analysis showed an increasing trend in Cr concentrations along the Madeira River, suggesting that contaminants present in the river are being carried over long distances and are reaching preserved areas of the Amazon.

Risk of exposure to Hg and pesticides residues in a traditional fishing community in the Amazon: a probabilistic approach based on dietary pattern.

Exposure to mercury (Hg) and pesticides (o.p'DDT, p.p'DDT, o.p'DDE, and p.p'DDE) in the Amazon through eating fish is of concern due to the large participation of this food in the diet of traditional fishing communities. The aim of this study was to evaluate the estimated daily intake (EDI) and the incremental lifetime cancer risk associated with Hg and o.p'DDT, p.p'DDT, o.p'DDE, and p.p'DDE in an Amazonian community. The results showed that for Hg, the EDI from carnivorous and detritivorous fish had the highest values, while for pesticides, the EDI from detritivorous fish intake had the highest value. The incremental lifetime cancer risk was below the permitted limit. A recommendation for controlling the high risk of exposure includes the reduction of detritivorous fish ingestion and/or replacement with herbivorous fish, which had lower EDI. We highlight the importance of investigating the human dietary patterns when estimating risk of exposure to Hg and pesticides.

Arsenic in the lower drainage basin of the Paraíba do Sul River (Southeast Brazil): dynamics between the water column and sediment.

The presence of arsenic (As) in the sediment and the particulate and dissolved fractions of the water column determines its behavior and bioavailability. The main geochemical parameters responsible for As mobility are organic matter and oxide-forming metals such as Fe. The As distribution and its concentration were evaluated in the dissolved fraction, suspended particulate matter (SPM) and sediment of the lower Paraíba do Sul River (PSR), its main tributaries (Muriaé, Pomba, and Dois Rios rivers), and flooded and estuarine areas. As was not detected in the dissolved fraction. The river flow influenced the As concentration in the SPM, which was higher in the dry season than in the rainy season (2.6 ± 0.69 and 1.98 ± 0.29 mg kg-1, respectively). The Fe oxyhydroxides, organic carbon, and surface area measured in the sediment were positively related with As concentration (R2 = 0.11, 0.34, and 0.30; p < 0.05). The highest As concentrations in the sediment occurred in the secondary estuary and flooded areas (5.16 ± 4.78 and 1.23 ± 0.44 mg kg-1, respectively), in which finer granulometric fractions (silt and clay) predominated (64% and 71%, respectively), in addition to greater surface area. The measurement of stable carbon and nitrogen isotopes (δ13C and δ15N) and atomic ratio (C:N)a indicated the existence of a combination of autochthonous and allochthonous sources of organic matter composing the SPM. In general, the As concentrations in the sediment and SPM were low, with values below that permitted by Brazilian regulations (5.9 mg kg-1), which suggests that the As sources in the lower basin of the PSR are diffuse and natural.

Mercury biomagnification in an ichthyic food chain of an amazon floodplain lake (Puruzinho Lake): Influence of seasonality and food chain modeling.

Mercury (Hg) biomagnification in fish food chains is a relevant subject due to the high fish consumption of the Amazonian population and the high toxicity of this metal. In the Amazon, floodplain lake hydrodynamics change considerably along the four seasons of the hydrological cycle (rising water, high water, falling water and low water), which can influence Hg bioaccumulation in fish. The main aim of this study was to evaluate if Hg biomagnification is influenced by seasonality in a floodplain lake (Puruzinho Lake) in the Brazilian Amazon. Additionally, the influence of food chain modeling on measurement of Hg biomagnification was tested. Hg concentrations and stable isotope signatures (carbon and nitrogen) were estimated in four species, Mylossoma duriventre (herbivorous), Prochilodus nigricans (detritivorous), Cichla pleiozona (piscivorous) and Serrasalmus rhombeus (piscivorous). The "trophic magnification slope" (TMS) of the food chain composed by the four species was calculated and compared among the four seasons. There was no significant seasonal variation in TMS among rising water, high water, falling water and low water seasons (p = 0.08), suggesting that Hg biomagnification does not change seasonally. However, there was significant variation in TMS among different food chain models. Lower TMS was observed in a food chain composed of detritivorous and piscivorous fish (0.20) in comparison with a food chain composed of the four species (0.26). The results indicate food chain modeling influences TMS results.

Variation in Hg accumulation between demersal and pelagic fish from Puruzinho Lake, Brazilian Amazon.

Aquatic ecosystems in the Amazon are exposed to mercury, mostly from natural sources. Hg accumulation in fish tissues poses a risk to the local population since fish is one of the main sources of protein in the region. The aim of this study was to evaluate Hg distribution in demersal and pelagic carnivorous fish between seasons in Puruzinho Lake in the Brazilian Amazon. Total Hg was quantified in 221 individuals of 8 species obtained during the high water and low water seasons. Two-way ANOVA indicated an interaction between foraging habitat and season. During high water, total Hg concentrations were similar between demersal and pelagic fish, while in low water, total Hg levels were higher in demersal fish. Pelagic and demersal fishes' Hg levels were similar between the two seasons.

Exposure to toxic and essential trace elements through the intake of processed and meat cuts (beef and chicken) in southeastern Brazil.

The present study evaluated the concentration of six trace elements in processed meat products and in meat cuts. We also assessed the risk associated with the consumption of these foods based on the estimated daily intake (EDI) of these elements. Fifty-eight processed meat and 148 meat cuts samples were analyzed using ICP-OES. As and Cd were not detected in any sample of processed meat. The highest mean level of lead was observed in frankfurters (0.056 µg g-1), which is half the maximum permissible level. For Cr, the highest mean concentrations were detected in chicken nuggets and beef hamburger (0.121 and 0.105 µg g-1, respectively), which are above the allowed limit. The comparison between the impact of a diet restricted to processed meats with a diet restricted to meats cuts showed that the individuals following the latter are exposed to higher amounts of the trace elements analyzed.

Influence of the flood pulse on mercury accumulation in detritivorous, herbivorous and omnivorous fish in Brazilian Amazonia.

Hg accumulation in fish is influenced by several factors including seasonality. In the Amazon, ecosystems are marked by strong seasonal variation in precipitation, which leads to drastic changes in the water level of lakes and rivers. The aim of this study was to evaluate Hg levels in muscle of detritivorous, herbivorous and omnivorous fish from an Amazon lake (Madeira River Basin, Amazonas, Brazil) over four seasons (rising water, high water, falling water and low water). We hypothesized that total Hg concentration varies during the seasons. The results indicate that total Hg levels in detritivorous fish were higher in rising and low water seasons while in herbivorous and omnivorous fish the total Hg concentration was higher during the rising water season. The hypothesis was supported by the results. Additionally, the study provides evidence that Hg levels in fish with different feeding habits are influenced by the flood pulse of the Amazon region.

The impact of hydroelectric dams on mercury dynamics in South America: A review.

The increase in global demand for electric energy is reflected in plans to construct numerous hydroelectric dams in South America that can cause chronic ecological impacts if not built and managed correctly. One of the main impacts generated by hydropower dams is the accumulation of Hg chemical species in their reservoir compartments and the downstream transport of these contaminants. Hg circulation in these environments has been studied for 27 years and this review brings a synthesis of the dynamics that are now well established, so that future studies can focus on gaps and inconsistent results in the literature. The topics cover the methylation process of Hg, its transfer along the trophic chain and the impacts downstream from dams. In addition, meta-analyses are used to propose regression models that explain Hg dispersion in environmental compartments of reservoirs, using as predictors morphological, spatial and temporal aspects of these environments.

Risk of exposure to total and inorganic arsenic by meat intake among different age groups from Brazil: a probabilistic assessment.

Beef and poultry as well as cattle and chicken livers are staple food items for Brazilian population, and previous studies had detected arsenic levels in these foods. This study aims to evaluate the risk of exposure to total and inorganic arsenic by meat intake in three age groups from Brazil (11-16, 16-21, and > 21 years). Our hypotheses are (i) that there is differences in the risk of exposure between age groups and (ii) the older individuals (> 21 years) are under higher risk. To test these hypotheses, we calculated the probabilistic estimated daily intake of total As (TAsEDI) from poultry, beef, cattle liver, and chicken liver, and the probabilistic estimated incremental lifetime skin, bladder, and lung cancer risk (ILCR) associated with inorganic As ingestion from poultry only. TAsEDI and ILCR from poultry differed among groups which confirm the first hypothesis. However, TAsEDI and ILCR results cannot support the second hypothesis. Even though the age groups are under a low risk of exposure to As by meat intake, the results indicate that bladder/lung cancer risk (from poultry intake) slightly exceeds the safe limits in the older population.