Mercury Sources, Emissions, Distribution and Bioavailability along an Estuarine Gradient under Semiarid Conditions in Northeast Brazil

In the semiarid coast of northeast Brazil, climate change and changes in land use in drainage basins affect river hydrodynamics and hydrochemistry, modifying the estuarine environment and its biogeochemistry and increasing the mobilization of mercury (Hg). This is particularly relevant to the largest semiarid-encroached basin of the region, the Jaguaribe River. Major Hg sources to the Jaguaribe estuary are solid waste disposal, sewage and shrimp farming, the latter emitting effluents directly into the estuary. Total annual emission reaches 300 kg. In that estuary, the distribution of Hg in sediment and suspended particulate matter decreases seaward, whereas dissolved Hg concentrations increase sharply seaward, suggesting higher mobilization at the marine-influenced, mangrove-dominated portion of the estuary, mostly in the dry season. Concentrations of Hg in rooted macrophytes respond to Hg concentrations in sediment, being higher in the fluvial endmember of the estuary, whereas in floating aquatic macrophytes, Hg concentrations followed dissolved Hg concentrations in water and were also higher in the dry season. Animals (fish and crustaceans) also showed higher concentrations and bioaccumulation in the marine-influenced portion of the estuary. The variability of Hg concentrations in plants and sediments agrees with continental sources of Hg. However, Hg fractionation in water and contents in the animals respond to higher Hg availability in the marine-dominated end of the estuary. The results suggest that the impact of anthropogenic sources on Hg bioavailability is modulated by regional and global environmental changes and results from a conjunction of biological, ecological and hydrological characteristics. Finally, increasing aridity due to global warming, observed in northeast Brazil, as well as in other semiarid littorals worldwide, in addition to increased water overuse, augment Hg bioavailability and environmental risk and exposure of the local biota and the tradition of human populations exploiting the estuary's biological resources.

Ecological and biological factors associated to mercury accumulation in batoids (Chondrichthyes: Batoidea) from northeastern Brazil

The present study aims to understand how ecological and biological factors affect the Hg levels in stingrays occurring in the Northeastern Brazilian coast. Total mercury (Hg), methylmercury (MeHg) and stable isotope (δ¹³C and δ¹⁵N) analyses were performed in five species. Hypanus americanus and Gymnura micrura showed the highest total Hg concentrations (300 and 176 ng.g^-1, respectively). Hypanus guttatus exhibited a significant correlation between total Hg and size. Both species of the genus Hypanus presented the highest percentage of MeHg, around 100%, whereas the other species showed median percentages below 50%. The δ¹³C and δ¹⁵N signatures suggest that all studied species present the same foraging habitat but different trophic positions. Trophic position and animal size were the main factors influencing total Hg and MeHg concentrations in batoid species. The genus Hypanus, present in the Brazilian fish markets, showed concentrations above the accepted limits for human consumption.

Influence of size on total mercury (THg), methyl mercury (MeHg), and stable isotopes of N and C in green turtles (Chelonia mydas) from NE Brazil

The green turtle (Chelonia mydas) is known to present an herbivorous diet as an adult; however, juveniles may have an omnivore habit, and these changes in food preference may affect the uptake and accumulation of pollutants, such as mercury (Hg). In order to better understand the influence of this ontogenetic shift on Hg accumulation, this study evaluates the concentrations of total mercury (THg), methyl mercury (MeHg), and stable isotopes of carbon and nitrogen (δ¹³C and δ¹⁵N) in a group of juveniles of the green turtle. Tissue samples (liver, kidney, muscle, and scutes) were sampled from 47 turtles stranded dead on the coast of Bahia, NE, Brazil, between 2009 and 2013. The turtles analyzed showed a size range of 24.9-62.0 cm and an average of 36.4 ± 7.2 cm of curved carapace length. The scutes showed to be a viable method for Hg monitoring in the green turtles. The concentrations of THg and MeHg decreased with increasing size. The isotope values of δ¹⁵N and δ¹³C did not show a clear relationship with the size, suggesting that the green turtles used in our work would be occupying similar trophic levels, and foraging habitat.

Contrasting Mercury Bioavailability in the Marine and Fluvial Dominated Areas of the Jaguaribe River Basin, Ceará, Brazil

This study evaluates the influence of environmental and biological factors upon the mercury (Hg) concentrations in the aquatic fauna in the Lower Jaguaribe River Basin (LJRB) - NE, Brazil. Two campaigns conducted in 2015 in the fluvial (FDA) and in the marine-dominated (MDA) areas resulted in 830 organisms from 16 species collected (nine of finfish and seven of invertebrates). Among the invertebrates, the highest Hg concentration occurred in the crab Callinectes bocourti (201 ng g^-1), while among the finfish the highest concentration was found in the ladyfish Elops saurus (109 ng g^-1), both carnivorous and of high trophic level (TL). Intra-specific comparison showed significant higher Hg concentrations in individuals captured in the MDA. Also, Hg bioaccumulation rate in the shrimp Litopenaeus vannamei was much higher in the MDA. These results, point to a concomitant control of Hg bioavailability by physical-chemical variables along the estuarine gradient of the LJRB.

CAM providers' messages to conventional medicine: a qualitative study

Between 30 and 50% of patients use complementary and alternative medicine (CAM). There is little research on the interaction between CAM and conventional providers. We investigated what messages CAM practitioners would convey to conventional medicine (CM). Thirty-four CAM practitioners participated in audiotaped interviews. A coherent message was constructed from the identified themes. CAM practitioners see CAM supporting CM rather than replacing it. Blending of CAM with CM benefits patients and CM providers. CAM reintroduces the concept of healing that technology and time pressures have reduced. The basis of healing is connection, being present in the moment, and seeing patients as whole human beings. Research validating CAM effectiveness will foster integration, as will inclusion of CAM theory and practice in the medical curricula. The messages from CAM practitioners to CM coincide with current views of integrative medicine. Collaboration in research, education, and practice can foster a high-quality health care system.