Mercury distribution in organisms, litter, and soils of the Middle Araguaia floodplain in Brazil.

Mercury (Hg) is a chemical element that, depending on its concentration, may become toxic to living organisms due to the ability of Hg to bioaccumulate in food chains. In this study, we collected samples of soil, litter, and organisms in the Middle Araguaia floodplain, Brazil. Total mercury (THg) concentrations in litter were significantly higher (p < 0.0001) than that in soil, ranging from 10.68 ± 0.55 to 48.94 ± 0.13 and 20.80 ± 1.07 to 55 .19 ± 1.59 ng g-1, respectively. Total mercury concentration levels in soil showed a linear, inversely proportional relationship with soil organic matter (SOM) contents and soil pH, consistent with the geochemical behavior of chemical elements in flooded environments. Ten orders of organisms were identified, and the average THg concentrations determined in their bodies were up to 20 times higher than those in soil and litter. We found a significant linear relationship between the levels of THg in litter and those found in soil organisms, thereby allowing the prediction of THg concentration levels in soil organisms through the analysis of litter at the sample units. The different dynamics and feeding habits of soil organisms and the concentration of THg in these organisms may be influenced by the river's course. This study provides evidence of the bioaccumulation of THg in soil organisms in the floodplain of the Middle Araguaia River, an important river basin in the Brazilian savanna.

Adaptive capabilities and fitness consequences associated with pollution exposure in fish.

Many fish populations are exposed to harmful levels of chemical pollution and selection pressures associated with these exposures have led to the evolution of tolerance. Our understanding of the physiological basis for these adaptations is limited, but they are likely to include processes involved with the absorption, distribution, metabolism and/or excretion of the target chemical. Other potential adaptive mechanisms include enhancements in antioxidant responses, an increased capacity for DNA and/or tissue repair and alterations to the life cycle of fish that enable earlier reproduction. Analysis of single-nucleotide polymorphism frequencies has shown that tolerance to hydrocarbon pollutants in both marine and estuarine fish species involves alteration in the expression of the xenobiotic metabolism enzyme CYP1A. In this review, we present novel data showing also that variants of the CYP1A gene have been under selection in guppies living in Trinidadian rivers heavily polluted with crude oil. Potential costs associated with these adaptations could reduce fitness in unpolluted water conditions. Integrating knowledge of local adaptation to pollution is an important future consideration in conservation practices such as for successful restocking, and improving connectivity within river systems.This article is part of the themed issue 'Human influences on evolution, and the ecological and societal consequences'.

A chemical status predictor. A methodology based on World-Wide sediment samples.

As a consequence of the limited resources of underdeveloped countries and the limited interest of the developed ones, the assessment of the chemical quality of entire water bodies around the world is a utopia in the near future. The methodology described here may serve as a first approach for the fast identification of water bodies that do not meet the good chemical status demanded by the European Water Framework Directive (WFD). It also allows estimating the natural background (or reference values of concentration) of the areas under study using a simple criterion. The starting point is the calculation the World-Wide Natural Background Levels (WWNBLs) and World-Wide Threshold Values (WWTVs), two indexes that depend on the concentration of seven elements present in sediments. These elements, As, Cd, Cr, Cu, Ni, Pb and Zn, have been selected taking into account the recommendations of the UNEP (United Nations Environment Programme) and USEPA (United States Environmental Protection Agency), that describe them as elements of concern with respect to environmental toxicity. The methodology has been exemplified in a case study that includes 134 sediment samples collected in 11 transitional water bodies from 7 different countries and 4 different continents. Six of the water bodies considered met the good chemical status demanded by the WFD. The rest of them exceeded the reference WWTVs, at least for one of the elements. The estuaries of the Nerbioi-Ibaizabal (Basque Country) and Cavado (Portugal), the sea inlet of Río San Pedro (Spain), the Sepetiba Bay (Brazil) and the Yucateco lagoon (Mexico) belong to that group.

Propuesta de metodología de gestión ambiental para agro ecosistemas con riesgos a la salud por contaminación química / Proposed methodology of environmental management for agro ecosystems health risks for chemical contamination

Introducción: la gestión ambiental relaciona al ser humano como especie a su pasado y se dirige a caracterizar el presente para prever el futuro. Para lograr alcanzar un adecuado desarrollo de la actividad agrícola urbana se hace necesario emplear enfoques más integradores que logren visualizar los problemas ambientales que se presentan en el contexto agrícola actual. Objetivo: desarrollar una metodología de gestión ambiental para agroecosistemas con probables riesgos a la salud por presencia de contaminación química. Material y Métodos: se utilizaron los métodos teóricos de la investigación: histórico-lógico, análisis y síntesis, inductivo-deductivo e hipotético-deductivo. A partir del modelo conceptual de gestión ambiental para agroecosistemas con probables riesgos a la salud por contaminación química, se desarrolló la metodología, como una forma de llevar a la práctica la concepción teórica desarrollada. Resultados: la metodología relaciona coherentemente procedimientos y herramientas por medio de un proceso que transita por cuatro etapas y doce pasos. Estas etapas consisten en preparar, planear, ejecutar, controlar y evaluar las acciones que desde la gestión ambiental son necesarias para las transformaciones de los agroecosistemas contaminados y que influyen directamente sobre la salud humana, mediante un proceso cíclico e iterativo. Conclusiones: permite establecer un conjunto de acciones que son monitoreadas, y evaluadas de forma participativa entre los actores involucrados, lo que permite lograr el empoderamiento de los mismos con mejoras en la salud de los agroecosistemas y la salud de los pobladores(AU)

Introduction: environmental management related to humans like a species to its past and heads to characterize the present to predict the future. In order to reach a proper development of urban agriculture is necessary to use more integrative approaches that achieve visualize environmental problems that arise in the current agricultural context. Objective: to develop a methodology for environmental management for agro ecosystems with probable health risks due to the presence of chemical contamination. Material and Methods: historical and logical analysis and synthesis, deductive and inductive- hypothetical- deductive theoretical research methods were used. A conceptual model of environmental management for agro ecosystems likely risks to health from chemical contamination, the methodology was developed as a way to implement the theoretical concepts developed. Results: the methodology consistently related procedures and tools through a process that goes through four stages and twelve steps. These steps are to prepare, plan, implement, monitor and evaluate the actions that are necessary for environmental management for transformations of contaminated agro ecosystems and that directly influence human health through a cyclical and iterative process. Conclusions: sets a set of actions that are monitored and evaluated in a participatory manner among stakeholders, allowing the empowerment thereof with improved agro-ecosystem health and the health of the inhabitants(AU)

Ecotoxicology and testicular damage (environmental chemical pollution): a review

This review briefly considers the testicular damage elicited by environmental chemical pollution. It includes a short comment on environmental toxicology as an introduction to environmental chemical pollution, highlighting the importance of this current field of study and its impact on male reproductive health. Furthermore an experimental animal model addressing the effect of organophosphorated agropesticides as a testicular toxicant is presented. Moreover two relevant chemical contaminants and their effect on the testis, such as the classical case of lead and the rarely reported case of Boron on spermatogenesis, are considered. Additionally, the subject of biosentinel species and their relevance for the monitoring of pollution in aquatic and/or terrestrial ecosystems is considered. In conclusion, it should be stressed that environmental health is closely related to the reproductive health of all living beings.

Esta revisión considera el daño testicular provocado por la contaminación química ambiental. Incluye un breve comentario sobre toxicología ambiental a modo de introducción respecto a la polución química ambiental y destaca la importancia de este campo de estudio actual y su impacto sobre la salud reproductiva masculina. Además se presenta un modelo experimental animal concerniente al efecto de agropesticidas organofosforados como tóxicos testiculares. Se consideran dos contaminantes químicos relevantes y su efecto en el testículo como son el clásico caso del plomo y el menos conocido caso del boro y sus efectos sobre la espermatogénesis. También se trata el tema de las especies biocentinelas y su importancia para el monitoreo de la evolución de ecosistemas acuáticos y/o terrestres. En conclusión, es necesario insistir que la salud medioambiental está íntimamente relacionada con la salud reproductiva de todos los seres vivos.