Deposition of gold mining tailings in tropical soils: metal pollution and toxicity to earthworms

Journal of Soils and Sediments - This study consists of the evaluation of metals acute toxicity levels taking into consideration a hypothetic scenario of dam breaking and land deposition of two...     

Different isolates from Leishmania braziliensis complex induce distinct histopathological features in a murine model of infection

The aim of this study was to evaluate the histopathological features in tissues of mice infected by human isolates (I, II, and III) or the reference M2903 strain of Leishmania braziliensis complex. BALB/c and C57Bl/6 mice were infected in the hind footpad with 10⁶ stationary-phase promastigotes of L. braziliensis complex. The evolution of lesions was observed for 10 weeks and the animals were then euthanized and liver, spleen and popliteal lymph nodes were collected. Tissues were stained with hematoxylin and eosin and analyzed by immunohistochemistry assay. Increased thickness of infected footpads was observed in all animals, lesions were nodular and non-ulcerated. Mice infected with isolate I presented inflammatory infiltrates consisting predominantly of mononuclear cells in all tissues examined, and also a great number of megakaryocytes, compared with other isolates. Infection with isolate II led to an infected footpad enlargement not seen in other isolates. In addition, mononuclear infiltrates in the liver and hemosiderin in spleen were noted. Conversely, mice infected with either isolate III or M2903 strain only showed an increased number of megakaryocytes in spleen. All tissues examined had detectable amastigote forms of Leishmania by immunohistochemistry in all groups. Taking together, our results showed an unforeseen behavior of different isolates of L. braziliensis complex that led to diverse pathological findings.     

Carcass,meat quality traits,and economic analysis of Nellore bulls fed with finishing feedlot diets containing mechanically processed corn silage

In the livestock sector, strategies are available to mitigate gas emissions, such as methane, one of the alternatives that have shown potential correspondence to changes in the composition of the diet. The main aim of this study was to analyze the influence of methane emissions with data on enteric fermentation obtained from the Electronic Data Gathering, Analysis, and Retrieval (EDGAR) database and based on forecasts of methane emissions by enteric fermentation with an autoregressive integrated moving average (ARIMA) model and the application of statistical tests to identify the association between methane emissions from enteric fermentation and the variables of the chemical composition and nutritional value of forage resources in Colombia. The results reported positive correlations between methane emissions and the variables ash content, ethereal extract, neutral detergent fiber (NDF), and acid detergent fiber (ADF) and negative correlations between methane emissions and the variables percentage of unstructured carbohydrates, total digestible nutrients (TDN), digestibility of dry matter, metabolizable energy (MERuminants), net maintenance energy (NEm), net energy gain (NEg), and net lactation energy (NEI). The variables with the most significant influence on the reduction of methane emissions by enteric fermentation are the percentage of unstructured carbohydrates and the percentage of starch. In conclusion, the analysis of variance and the correlations between the chemical composition and the nutritive value of forage resources in Colombia help to understand the influence of diet variables on methane emissions of a particular family and with it in the application of strategies of mitigation.

     

Fish contamination and human exposure to mercury in Tartarugalzinho River,Amapa State,Northern Amazon,Brazil. A screening approach

This study reports for the first time, the Hg concentrations in the fish fauna of the Tartarugalzinho river basin - an important gold mining region in Amapa State, Northern Amazon - and evaluates human exposure to Hg due to fish consumption in the area. We analyzed 16 fish species (carnivorous and omnivorous) common in the aquatic environment of the Tartarugalzinho area and which are mostly consumed by the local population. Mercury concentrations in fish ranged from 35 µg.kg-1 to 1,225 µg.kg-1. Among the analyzed fish, 8 species (50%) presented Hg concentrations higher than 500 µg.kg-1, the U.S. Food and Drug Administration (FDA) Action Level for concentration of Hg in fish. No statistical difference was observed between Hg mean concentrations in carnivorous and omnivorous fish. Within a given species, Hg concentrations were positively correlated with fish size or weight. The Hg concentration ratio between fish and water showed values higher than 50,000. Human exposure was estimated through the daily Hg intake obtained through interviews with the local population on the amount and species of fish consumed and the Hg concentration in the fish. The estimated average daily intake was 114 µg.day-1. This amount is approximately one-half of the WHO recommended provisional tolerable Hg weekly intake. At screening level, it assumes that there is a level of exposure (e.g, USEPA's RfD = Reference of Dose) below which it is unlikely for even sensitive populations to experience adverse health effects. The estimated exposure level for adult humans (1.6 µg.kg-1.day-1) was nearly 5 times greater than Hg RfD (0.3 µg.kg-1.day-1). The results suggest a widespread Hg contamination in the local fish fauna. Due to high fish Hg concentrations and high fish intake by local population, environmental exposure to Hg is also high, presenting a health risk to population.     

Technogenic deposits formed from dredged sediments deposition: toxic effects on earthworms

Journal of Soils and Sediments - Dredged sediments are often disposed on land areas and can cause adverse effects on soil biota, since these materials generally may contain toxic agents. This work...