Mercury distribution, bioaccumulation, and biomagnification in riparian ecosystems from a neotropical savanna floodplain, Araguaia River, central Brazil.

Litterfall is the main source of dry deposition of mercury (Hg) into the soil in forest ecosystems. The accumulation of Hg in soil and litter suggests the possibility of transfer to terrestrial invertebrates through environmental exposure or ingestion of plant tissues. We quantified total mercury (THg) concentrations in two soil layers (organic: 0-0.2 m; mineral: 0.8-1 m), litter, fresh leaves, and terrestrial invertebrates of the Araguaia River floodplain, aiming to evaluate the THg distribution among terrestrial compartments, bioaccumulation in invertebrates, and the factors influencing THg concentrations in soil and invertebrates. The mean THg concentrations were significantly different between the compartments evaluated, being higher in organic soil compared to mineral soil, and higher in litter compared to mineral soil and fresh leaves. Soil organic matter content was positively related to THg concentration in this compartment. The order Araneae showed significantly higher Hg concentrations among the most abundant invertebrate taxa. The higher Hg concentrations in Araneae were positively influenced by the concentrations determined in litter and individuals of the order Hymenoptera, confirming the process of biomagnification in the terrestrial trophic chain. In contrast, the THg concentrations in Coleoptera, Orthoptera and Hymenoptera were not significantly related to the concentrations determined in the soil, litter and fresh leaves. Our results showed the importance of organic matter for the immobilization of THg in the soil and indicated the process of biomagnification in the terrestrial food web, providing insights for future studies on the environmental distribution of Hg in floodplains.

A 35-Year Record (1987-2022) of Hg Concentrations in Two of the Fish Species Most Consumed by People Living in the Upper Madeira River Basin, Brazilian Amazon Region.

This study presents a 35-year record of total mercury (Hg) concentrations in the detritivore fish Prochilodus nigricans (Curimatã) and the carnivore Cichla pleiozona (Tucunaré), two of the most widely distributed, ecologically important and consumed fish species in the upper Madeira River Basin in the Western Brazilian Amazon. Fish samples from the major Madeira River and marginal lakes and tributaries were compared. Irrespective of site, Hg concentrations were higher in the carnivore fish compared to the detritivore. Hg concentrations increased 5-fold in C. pleiozona in the past three decades, whereas they remained relatively constant in P. nigricans when analyzing the entire 35-year period. When analyzed separately, fish in the main river and marginal lake and tributaries presented the same pattern of Hg variation, with a significant increase in Hg concentrations in the carnivore and in the detritivore in marginal lakes and tributaries but not in the main river. This was in line with the increase in methyl-Hg production in tributaries, mostly associated with deforestation in the past decade in the basin. Although an increase in direct emissions from artisanal gold mining also occurred in the past decade, this caused virtually no impact on fish Hg concentrations, suggesting atmospheric emission and deposition in forests and further export to water systems as an intermediate link with fish Hg concentrations.

Evaluating total mercury and methylmercury biomagnification using stable isotopes of carbon and nitrogen in fish from the Madeira River basin, Brazilian Amazon.

The isotopic signatures of carbon in primary consumer fish species in the Madeira River basin (Western Amazon) follow a pattern, with basal species feeding mainly on C3 (e.g., vascular plants and phytoplankton). In this study with 196 specimens of 19 fish species and six trophic guilds, significant differences were found between the two main groups of primary consumers (herbivores and detritivores) in the Madeira River basin. The mercury and δ15N data indicated that the fish specimens collected in Puruzinho and Cuniã Lakes provided greater trophic magnification factors (TMFs) for this metal than those found in the corresponding rivers. In relation to total mercury (0.09-2.07 µg g-1) and methylmercury (0.05-1.91 µg g-1) concentrations, the piscivorous/carnivorous species exceeded the values recommended by the World Health Organization, with a [MeHg:THg] ratio of about 80%. Preventive and educational practices should be adopted to reduce the possible toxic effects of Hg in the riverside population, for whom fish constitutes the main protein source. Also, biomonitoring of the fish species in the Madeira River should be conducted on an ongoing basis to detect possible alterations in mercury concentrations.

Mercury in blood, hair, and feces from subsistence fish-eating riverines of the Madeira River Basin (Western Amazon).

BACKGROUND: The Madeira River (Amazon Basin) has been impacted by activities related to artisanal and small-scale gold mining (ASGM), deforestation and burning (for timber, agriculture, and hydroelectric dam projects). All these activities contribute to environmental mercury (Hg) release and cycling into the Amazon ecosystem and thus to changing lifestyles. METHOD: We assessed exposure to total and MeHg in two small riverine communities of the Madeira River (Amazon): Lago Puruzinho (LP, n = 26 families) and São Sebastião do Tapurú (SST, n = 31 families). Samples of human hair (n = 137), blood (n = 39), and feces (n = 41) were collected from adults and children (0-15 years of age). RESULTS: In women of childbearing age from LP village, the mean blood total-Hg (THg) (45.54 ±â€¯24.76 µg.L-1) and MeHg (10.79 ±â€¯4.36 µg.L-1) concentrations were significantly (p = 0.0024; p < 0.0001, respectively) higher than in women from SST village (THg: 25.32 ±â€¯16.75 µg.L-1; MeHg: 2.32 ±â€¯1.56 µg.L-1) village; the trend in hair-Hg persisted but was statistically significant (p < 0.0145) only for THg (LP, 11.34 ±â€¯5.03 µg. g-1; SST, 7.97 ±â€¯3.51 µg. g-1). In women, the median hair:blood ratio of total Hg was 269. In children, the mean hair THg concentrations were 6.07 ±â€¯3.60 µg. g-1 and 6.47 ±â€¯4.16 µg. g-1 in LP and SST; thus, not significantly different (p = 0.8006). There was a significant association (p < 0.001) between hair-Hg concentrations of mothers and their respective children. The excretion of Hg in feces of women (0.52 µg. g-1 dw) was not significantly different from children (0.49 µg. g-1 dw). The only statistically significant correlation between Hg in feces and in hair was found in children, (n = 16, rs = 0.38, p = 0.005). Significant relationship was seen between the levels of THg in blood and hair of women from LP and SST. Based on hair-Hg concentrations, fish consumption rate ranged from 94.5 to 212.3 g.day-1. CONCLUSION: Women and children excrete THg in feces in comparable concentrations. However, the mean fish consumption rate and blood MeHg are higher in the most remote villagers. Mother`s hair-Hg concentration is a good predictor of children's hair-Hg.

Total mercury and methylmercury in river dolphins (Cetacea: Iniidae: Inia spp.) in the Madeira River Basin, Western Amazon.

In the Amazon, mercury (Hg) contamination comes from ASGM operations along with soil remobilization processes associated with deforestation. The objective of this study was to evaluate the exposure to methylmercury (MeHg) and total mercury (THg) in 88 samples of skin and blubber tissue obtained from live captured river dolphins (Inia boliviensis, Inia geoffrensis, and Inia spp.) in the Madeira River Basin. THg and MeHg measurements were performed by CV-AAS and GC-AFS, respectively. We also calculated the daily intake rate (DIR) of THg (wet weight) by Inia spp. THg levels in blubber tissue of adult river dolphins (Inia spp.) ranged from 0.015 to 3.804 mg kg-1, while MeHg concentrations in blubber tissue varied from 0.04 to 2.65 mg kg-1 and in skin tissue from 0.09 to 0.66 mg kg-1. There were no significant differences in MeHg concentration in blubber (p = 0.616) and skin (p = 0.498) tissue samples between adult males and females in the different sampling locations. The adult animals showed differences in THg and MeHg concentrations significantly higher than in the calves. The estimate of the DIR of the genus Inia ranged from 1.17 to 12.35 µg kg-1 day-1 (bw), from the consumption of fish species with herbivorous to piscivorous habits, respectively. More biological and ecological data, such as the precise determination of age, mediated length, weight, and diet of river dolphins, are necessary to verify the Hg biomagnification. However, our data indicate that bioaccumulation is an active process in the dolphins of the Madeira River Basin.

Total and methyl-mercury in hair and milk of mothers living in the city of Porto Velho and in villages along the Rio Madeira, Amazon, Brazil.

High fish consumption and extended breastfeeding are hallmarks of traditional lifestyle in Western Amazonia. We studied sources of mercury exposure, fish-methylmercury (meHg) and dental-amalgam filling, in 75 urban and 82 rural lactating mothers. Total mercury was determined in all samples while meHg concentrations were determined in subsamples of milk (45) and hair (27) of urban mothers living in Porto Velho (PV) and in hair (46) and milk (37) of mothers living in traditional communities (TC) of the Rio Madeira. The TC mothers showed significantly higher median hair-Hg concentrations (8.2µgg(-1)) than PV mothers (1.3µgg(-1)). Median total Hg in milk of PV mothers (0.36ngg(-1)) was significantly lower (p=0.0000) than that found in milk of TC mothers (2.30ngg(-1)). The median meHg concentrations in milk of TC mothers were also significantly higher (1.0ngg(-1)) than in milk of PV mothers (0.07ngg(-1)). For urban mothers with low fish consumption rates (and relatively higher dental amalgam fillings) the proportion of inorganic Hg in milk was higher (85%) than in TC (62%). In TC mothers 51% of breast milk Hg concentrations were above 2ngg(-1) (world median concentrations), contrasting with 8% in PV mothers. Despite this, there was no significant correlation between total Hg concentrations in milk and either amalgam filling or daily fish consumption. Socioeconomic changes occurring in Western Amazonia are causing changes in fish-eating habits of urban mothers. However, traditional lifestyle and attendant high fish consumption in riverine populations can still impact total Hg and methylmercury concentrations in mothers' milk and hair.

Thermal comfort and personal protective equipment (PPE).

Personal Protective Equipment (PPE) is considered the last preferred solution to an Occupational Safety Health (OSH) system. Brazilian OSH legislation assumes and requires PPE usage to neutralize the possibility of pesticide contamination. This study examines the inadequacy of the PPE used in a tomato crop, particularly from the standpoint of thermal comfort. This study made observations regarding heart rate and body temperature in a controlled environment using a treadmill (with and without PPE) of 12 volunteers; and during the process of rural labor (at rest and in normal work routine) of 2 actual rural workers. Comparing the results of the treadmill test (with and without PPE) which tried to reproduce the same level of effort and environmental conditions of the actual rural work, this study demonstrated that PPE makes thermoregulation harder and tympanic temperature reaches higher values with the same level of effort. Moreover, body temperature increases quickly: with PPE it took 15 minutes to raise 1°C in body temperature, compared to 40 minutes without PPE. The results of this study indicated that the use inadequate PPE might pose thermoregulation risk to rural workers.

Annual flooding and fish-mercury bioaccumulation in the environmentally impacted Rio Madeira (Amazon).

Regular annual flooding of the Amazonian rivers changes the aquatic environment affecting fish feeding strategies. The Rio Madeira has been greatly impacted by deforestation for agricultural projects, damming for a hydroelectric power plant, and alluvial gold extraction. We studied fish-Hg concentrations within defined weight ranges of representative species at the top of the food web, comparing high and low water seasons. Selected piscivorous species (Cichla spp, Hoplias malabaricus, Pinirampus pirinampu, Serrasalmus spp) showed a large variation of Hg concentrations but only "traíra" (Hoplias malabaricus) showed a statistically significant difference between seasons. However, the bioaccumulation trends during high and low waters were similar for "tucunaré" (Cichla spp) and "traíra" (Hoplias malabaricus) but different for "piranhas" (Serrasalmus spp), "barba chata" (Pinirampus pirinampu) and the detritivorous Prochilodus nigricans. Fish-Hg bioaccumulation is species specific; changes in feeding strategies brought by flooding seasons can change the bioaccumulation pattern without systematically affecting the overall accrual of methylmercury in tertiary consumer species. It appears that naturally occurring Hg and the high sediment load of the Rio Madeira are secondary factors in the Hg bioaccumulation pattern of fish species at the top of the food chain.

Bomba acionada por um rotor Savonius submerso

Summary The construction of a pump powered by river currents using a submerged Savonius rotor is described in detail. The design is very simple, so that anybody can construct the pump using hand tools. The cost of materials for the unit is aproximately US$ 70,00. There is a slight variation in the performance of pumps of this type due to the rustic construction. Nevertheless, at maximum power a pump installed in a current of 0,6 m.seg.-1 (2,2 km/h) pumped 2100 litres of water per day with a head of 28 m. Another pump installed in a current of 1,1 m.seg.-1 (4,0 km/h) pumped 3100 litres with the same head. At lower pressures the pumping rate increased to between 3500 and 3900 litres per day. Since the pump can improve the domestic comfort of the rural riversidade population and/or supply water for other purposes it is hoped that the design will be widely popularised. Contacts with Government bodies are being developed with this aim.

Resumo A construção de uma bomba de água acionada por correntezas de rios mediante um rotor Savonius submerso está descrita em detalhe. O desenho da bomba é muito simples, de maneira que a construção pode ser feita por qualquer pessoa usando ferramentas manuais. O custo de materiais para fazer uma bomba é de US$ 70,00. Há uma leve variação no desempenho de bombas deste tipo devida à construção artesanal. Contudo uma bomba desenvolvendo potência máxima instalada num local com uma correnteza de 0,6 m.seg.-1 (2,2 km/h) jogou 2100 litros de água por dia a uma altura de 28 m e uma outra bomba instalada num local com uma correnteza de 1.1 m.seg.-1 (4,0 km/ h) jogou 3100 litros de água à mesma altura. Com pressões menores a vazão aumentou até a faixa de 3500 até 3900 litros por dia. Como a bomba pode proporcionar conforto ao morador ribeirinho e/ou fornecer água para outras finalidades, é de esperar-se que o desenho seja divulgado ativamente. Contatos com entidades governamentais vêm sendo desenvolvidos com esta finalidade.

Desempenho de um aquecedor solar de água em Manaus

Summary A commercial, domestic solar water heater was tested in Manaus during the whole year round. The performance was monitored using various parameters: incident solar radiation, temperature of water in the tank and at the entrance and exit of the collectors, as well as the velocity of the thermosiphon The latter was measured by injecting printing ink into the pipework which was fitted with transparent plastic windows in appropriate places. The efficiency of the collectors was seen to vary during the day. The maximum value ever observed was 58% and values of 37% are calculated for the data described In detail. Collector angle in the range 4°25° did not affect performance significantly Hot water for showers (150 l) at > 45°C should be obtained in 93% of the days of the year.

Resumo Um aquecedor solar de água comercial para fins domésticos foi testado em Manaus tanto no verão quanto no inverno. O desempenho foi medido em função da radiação incidente, observando-se a temperatura da água no reservatório e na entrada e na saída do coletor. A velocidade de termossifonagem foi medida através de uma injeção de tinta em tubulação transparente. A eficiência variou durante o dia. O valor máximo observado foi do 58% e valores de 37% são mostrados nos dados analisados em detalhe. O ângulo de inclinação (de 4 até 25°) não teve influência significativa no desempenho dos coletores. Agua quente (150 l) acima de 45°C seria obtida em pelo menos 93% dos dias do ano.

Hidreletricidade do rio Solimões usando um "cata-água"

Summary Eletricity was generated by the current of the Amazon river (rio Solimões) using an apparatus ressembling an underwater windmill. The machine, a free-floating structure ancored to the river-bed, comprised a twelve-bladed, fantype turbine of 2m. diametre held submerged beneath two floates, facing the current. A bicycle chain around the circumference of the turbine transmitted the rotation via multiplying gears to a car alternator. In a current of 0,6 m.s.-1 the power generated was 40 W representing an overall eficiency of 12%. The experiment demonstrates the feasability of generating power from river currents without using dams or waterfalls. The technology is considered highly appropriate to the Amazonian region where a rural eletricity grid is enexistent. Work is continuing on the design of a commercial unit.