Energy resource reallocation in Daphnia schodleri (Anomopoda: Daphniidae) reproduction induced by exposure to hexavalent chromium

Cladocerans are able to store energy in the form of macromolecules such as proteins, lipids and carbohydrates. However, their ability to do so depends to a large extent on their physiological and reproductive condition as well as their age. These macromolecules constitute the total caloric reserves of the body and may be modified as a result of environmental stress conditions by either physical or nutritional factors or by exposure to toxic compounds. Neonates of the freshwater cladoceran Daphnia schodleri were exposed to 0.0064, 0.032 and 0.064 mg L⁻¹ of hexavalent chromium - Cr(VI) - up to age 5, 7, 14, 21 or 28 d. Survival and fecundity of parthenogenetic females was evaluated for 28 d (maximum exposure period). Body length and maximum width were determined in specimens of all ages. Caloric content was evaluated in progeny and females within each age group. Female survival was significantly lower with exposure to 0.064 mg L⁻¹ of Cr(VI) than with other treatments, and negative effects on reproduction were observed from the lowest concentration on. Largest adult size was attained by control specimens towards the end of the observation period, but no significant differences in neonate size occurred between concentrations. Energy content decreased in adults as toxicant concentration increased, but these females allocated a larger amount of energy reserves to their progeny as a possible compensation aimed at ensuring neonate survival in an adverse environment due to toxicant presence. Sublethal concentrations of Cr(VI) modified energy content in D. schodleri, affecting to varying degrees its survival, growth and reproduction.     

New indexes for compound prioritization and complexity quantification on environmental monitoring inventories

Introduction  

Lists of compounds resulting from environmental monitoring may be conveniently represented in a very general way using Pareto distributions, after ranking them on descending order according to their concentration or hazard quotient expressed as percentages, depending on whether the objective of the monitoring is focussed on mass load occurrence or risk assessment respectively.     

Characterization of the olfactory impact around a wastewater treatment plant: optimization and validation of a hydrogen sulfide determination procedure based on passive diffusion sampling

A monitoring program based on an indirect method was conducted to assess the approximation of the olfactory impact in several wastewater treatment plants (in the present work, only one is shown). The method uses H2S passive sampling using Palmes-type diffusion tubes impregnated with silver nitrate and fluorometric analysis employing fluorescein mercuric acetate. The analytical procedure was validated in the exposure chamber. Exposure periods ofat least 4 days are recommended. The quantification limit of the procedure is 0.61 ppb for a 5-day sampling, which allows the H2S immission (ground concentration) level to be measured within its low odor threshold, from 0.5 to 300 ppb. Experimental results suggest an exposure time greater than 4 days, while recovery efficiency of the procedure, 93.0+/-1.8%, seems not to depend on the amount of H2S collected by the samplers within their application range. The repeatability, expressed as relative standard deviation, is lower than 7%, which is within the limits normally accepted for this type of sampler. Statistical comparison showed that this procedure and the reference method provide analogous accuracy. The proposed procedure was applied in two experimental campaigns, one intensive and the other extensive, and concentrations within the H2S low odor threshold were quantified at each sampling point. From these results, it can be concluded that the procedure shows good potential for monitoring the olfactory impact around facilities where H2S emissions are dominant.     

Inhibition of the antioxidant activity of catalase and superoxide dismutase from Fusarium verticillioides exposed to a Jacquinia macrocarpa antifungal fraction

The aim of this study was to investigate the in vitro effect of an antifungal fraction obtained from Jacquinia macrocarpa plant (JmAF) in the generation of reactive oxygen species (ROS) and the activity of the catalase (CAT) and superoxide dismutase (SOD) enzymes from Fusarium verticillioides, as well as their influence in the viability of the fungus spores. The compounds present in the JmAF were determined by gas chromatography/quadrupole time-of-flight mass spectrometry (GC/QTOF-MS). The effect of the exposition to JmAF on the generation of ROS, as well as in the CAT and SOD activities in F. verticillioides, was determined. The main compounds detected were γ-sitosterol, stephamiersine, betulinol and oleic acid. JmAF showed very high ability in inhibiting the spore viability of F. verticillioides, and their capacity to cause oxidative stress by induction of ROS production. JmAF induced the highest ROS concentration and also inhibited CAT and SOD activities. The results obtained in this study indicate that JmAF is worthy of being considered for the fight against phytopathogenic fungi.     

A comparative study of heavy metal accumulation and antioxidant responses in Vaccinium myrtillus L. leaves in polluted and non-polluted areas

The purpose of this study was to explore a possible relationship between the availability of metals in soil (Cd, Fe, Mn, Pb and Zn) and their concentrations in leaves of Vaccinium myrtillus L. as a species which has been reported to be a successful colonist of acid-and-heavy metal-contaminated soil. Analysis also concerned the antioxidant response of plants from three heavily polluted (immediate vicinity of: zinc smelter, iron smelter and power plant) and three relatively clean sites (nature reserve, ecological site and unprotected natural forest community) in southern Poland. The contents of glutathione, non-protein thiols, protein, proline and activity of guaiacol peroxidase in leaves of bilberry were measured. Generally, the concentrations of metals in the HNO₃ and CaCl₂ extracants of the soil from the polluted sites were higher. Moreover, the antioxidant responses were also elevated in bilberries in the polluted sites. Significant positive relationships between Cd, Pb and Zn concentrations in soil and in the plants were found. In the leaves of V. myrtillus from the polluted sites, higher concentrations of Cd, Pb and Zn were noted (In Miasteczko ?l?skie respectively 6.26, 157.09 and 207.17 mg?kg^?1?d.w.). We found a positive correlation between the increase in the NPTs and protein contents as well as the Cd, Pb and Zn concentrations in V. myrtillus. Cd, Pb and Zn also decreased guaiacol peroxidase activity. However, the activity of this enzyme increased under Fe. A decreasing trend in glutathione contents was observed with increasing iron and manganese concentrations in bilberry leaves. Parameters such as protein, non-protein –SH groups and changes in GPX activity seem to be universal, sensitive and correlated well with heavy metal stress.     

Bisphenol A migration from plastic materials: direct insight of ecotoxicity in Daphnia magna

Bisphenol A (BPA) is an endocrine disrupting chemical (EDC) whose migration from food packaging is recognized worldwide. However, the real overall food contamination and related consequences are yet largely unknown. Among humans, children’s exposure to BPA has been emphasized because of the immaturity of their biological systems. The main aim of this study was to assess the reproductive impact of BPA leached from commercially available plastic containers used or related to child nutrition, performing ecotoxicological tests using the biomonitoring species Daphnia magna. Acute and chronic tests, as well as single and multigenerational tests were done. Migration of BPA from several baby bottles and other plastic containers evaluated by GC-MS indicated that a broader range of foodstuff may be contaminated when packed in plastics. Ecotoxicological test results performed using defined concentrations of BPA were in agreement with literature, although a precocious maturity of daphnids was detected at 3.0 mg/L. Curiously, an increased reproductive output (neonates per female) was observed when daphnids were bred in the polycarbonate (PC) containers (145.1?±?4.3 % to 264.7?±?3.8 %), both in single as in multigenerational tests, in comparison with the negative control group (100.3?±?1.6 %). A strong correlated dose-dependent ecotoxicological effect was observed, providing evidence that BPA leached from plastic food packaging materials act as functional estrogen in vivo at very low concentrations. In contrast, neonate production by daphnids cultured in polypropylene and non-PC bottles was slightly but not significantly enhanced (92.5?±?2.0 % to 118.8?±?1.8 %). Multigenerational tests also revealed magnification of the adverse effects, not only on fecundity but also on mortality, which represents a worrying trend for organisms that are chronically exposed to xenoestrogens for many generations. Two plausible explanations for the observed results could be given: a non-monotonic dose–response relationship or a mixture toxicity effect.     

Mercury, methylmercury, and selenium in blood of bird species from Doñana National Park (Southwestern Spain) after a mining accident

Total mercury (Hg), monomethylmercury (MeHg), and selenium (Se) were determined in blood of 11 bird species living in Doñana National Park (DNP, Southwestern Spain) and the surrounding area in 1999 and 2000 after a mine spill accident. The total Hg contents found varied from 1.00 to 587 ng/mL, with an MeHg percentage higher than 80 %, except in mallard species. In all the cases, the concentrations found were below the threshold of high risk for the bird populations. The parameters which most affected the accumulation of Hg and MeHg in the birds studied were, first, species, or trophic position, and second sampling area. Age does not seem to have a great influence on the content of Hg in the blood of these birds. The levels of Se found ranged from 108 to 873 ng/mL, and they were not affected by species, trophic level, age, or sampling area. The blood Hg concentrations of birds living in the area directly affected by the toxic mud, outside the park, were higher than those found in the other birds, and this could be explained by the mine spill accident happened in 1998.     

Levels of organochlorine pesticides in Amazon turtle (Podocnemis unifilis) in the Xingu River,Brazil

Abstract

Due to the toxicity and high environmental persistence of organochlorine pesticides in aquatic organisms, turtles have been studied as environment biomonitors. These animals are important sources of protein for the riverside and indigenous peoples of the Brazilian amazon. In the present study, organochlorine pesticide contamination was investigated in Podocnemis unifilis. Liver, muscle and fatty tissue samples were removed from 50 specimens collected from five sampling points located in the Xingu River basin. Fourteen organochlorine pesticides were analysed via gas chromatography with an electron capture detector (CG-ECD). Eight organochlorine pesticides were detected with average concentrations of ∑DDT, ∑Endossulfan and ∑HCH which were 26.17?±?26.35, 14.38?±?23.77 and 1.39?±?8.46?ng g^?1 in moisture content, respectively. DDT compounds were the most predominant, with a greater concentration of pp′-DDT in the liver and pp′-DDD in the muscle. Significant differences were noted between the types of tissues studied, and the concentration of OCPs varied between sampling sites.