Changes in metabolic substrates during early development in anchoveta Engraulis ringens (Jenyns 1842) in the Humboldt Current

We assessed the ontogenetic changes in protein content and free amino acids (FAA) in eggs and early larvae of Engraulis ringens (anchoveta) off central Chile on different dates during the spawning season. On all sampling dates, a reduction in embryonic yolk-sac volume, proteins and FAA concentrations occurred during development. Protein electrophoresis (SDS–PAGE) of eggs and larvae showed at least 22 protein bands: 11 were consumed early and not detected after hatching. The proportion of essential FAA (EFAA) was higher than the proportion of non-essential FAA (NEFAA) in early eggs and in 7 day-old larvae (82.5-73% EFAA respectively). During egg development, the FAA pool was dominated by leucine, alanine and lysine, three amino acids contributing 35–44% of the total FAA in eggs. During larval development, histidine was the most abundant FAA. In July, total FAA constituted 13–18% of the egg dry weight. A similar proportion (45–51%) occurred in July between protein plus FAA and total lipids. The differences in egg size during the spawning season along with variability in batch composition suggests that the female spawning condition is a major factor determining egg quality and early offspring success.     

Synergistic effect of Glomus intraradices and Frankia spp. on the growth and stress recovery of Alnus glutinosa in an alkaline anthropogenic sediment

The presence of actinorhizas and arbuscular mycorrhizas may reduce plant stresses caused by adverse soil conditions. A greenhouse experiment was conducted using a sediment with a high pH, resulting from the disposal of waste originated at an acetylene and polyvinylchloride factory, in which Black alder (Alnus glutinosa) seedlings were inoculated either with Glomus intraradices BEG163 (originally isolated from the same sediment), Frankia spp. or both symbionts. After a 6-month growth period, plants inoculated with both symbionts had significantly greater leaf area, shoot height and total biomass when compared with the uninoculated control, the Frankia spp. and the G. intraradices treatments alone. In dual inoculated plants the N and P leaf content was significantly increased. A defoliation experiment was performed to evaluate the stress recovery of A. glutinosa and plants inoculated with both symbionts had a faster leaf regrowth and produced greater numbers of leaves. The dual inoculation resulted in greater numbers of and larger root nodules than when inoculated with Frankia spp. alone. The length and NADH diaphorase activity of the extraradical mycelium of G. intraradices was also significantly greater when dual inoculation was performed. The inoculation with Frankia spp. alone was shown to improve A. glutinosa growth, whereas G. intraradices alone had no positive effect under these environmental conditions. However, when the two symbionts were inoculated together a synergistic effect was observed resulting in a greater benefit for the plants and for both symbionts. The relevance of these findings for the phytorestoration of anthropogenic stressed sediments with high pH is discussed.     

Effect of food level on the acute and chronic responses of daphnids to lindane

The toxic effects of lindane on the zooplankton communities may be strongly related to the population fitness, which is highly dependent on food availability. In order to test this hypothesis, acute (immobilisation) and chronic (life-history) responses of Daphnia longispina and Daphnia magna, reared at different food levels (low, normal, and high), were assessed in laboratorial exposures to several concentrations of lindane. A bifactorial design was employed (food level versus lindane concentration) for both species. Results showed that lindane was toxic to both D. magna and D. longispina, within a similar range. However, lindane toxicity to daphnids was dependent on food level, suggesting that the latter is an important factor to take into account when assessing the toxic effects of lindane on zooplankton communities.     

Exergy losses during recycling and the resource efficiency of product systems

Recycling materials have always some degree of contamination. The presence of contaminations in the recycling streams causes a shift in the original composition of the materials to recycle. As a consequence, their quality may decrease with each recycling step. Additionally, lower quality resources are produced from resource streams that had initially a higher quality. These quality losses cannot be measured by mass balances, as the quality degradation cannot be translated by mass measures alone. To account all losses caused by recycling contaminations, all downstream recycling processes required to bring the materials back to the resource cycles must be included. This article describes a method to calculate the exergy content and exergy losses of metal solutions during recovery and recycling. The losses attributed to recycling, namely the material losses, the contamination losses with other metals, and the consequent need for dilution can be used as indicators of the quality loss of materials and of the efficiency of resource use in product systems. Therefore, exergy is proposed here as a measure of the efficiency of resources use.     

Coyotes,deer, and wildflowers: diverse evidence points to a trophic cascade

Spatial gradients in human activity, coyote activity, deer activity, and deer herbivory provide an unusual type of evidence for a trophic cascade. Activity of coyotes, which eat young mule deer (fawns), decreased with proximity to a remote biological field station, indicating that these predators avoided an area of high human activity. In contrast, activity of adult female deer (does) and intensity of herbivory on palatable plant species both increased with proximity to the station and were positively correlated with each other. The gradient in deer activity was not explained by availabilities of preferred habitats or plant species because these did not vary with distance from the station. Does spent less time feeding when they encountered coyote urine next to a feed block, indicating that increased vigilance may contribute, along with avoidance of areas with coyotes, to lower herbivory away from the station. Judging from two palatable wildflower species whose seed crop and seedling recruitment were greatly reduced near the field station, the coyote–deer–wildflower trophic cascade has the potential to influence plant community composition. Our study illustrates the value of a case-history approach, in which different forms of ecological data about a single system are used to develop conceptual models of complex ecological phenomena. Such an iterative model-building process is a common, but underappreciated, way of understanding how ecological systems work.     

Photodegradation of Diquat and Paraquat in aqueous solutions by titanium dioxide: evolution of degradation reactions and characterisation of intermediates

The titanium dioxide assisted photodegradation of Diquat and Paraquat herbicides solutions has been the subject of the present investigation, considering its direct application in the treatment of contaminated waters and soils. To have a better understanding of the photodegradation process, different types of TiO2, commercial and 'home prepared' Ti(1-x)FexO2 (x = 0% and 4%), were used as catalysts, using an UV light as radiation source. The degradation reactions were followed by UV spectroscopy and the intermediates and reaction products were characterised by electrospray ionisation mass spectrometry (ESIMS) combined with collision-induced dissociation (CID) and tandem mass spectrometry (MS/MS). The present study shows that, for photocatalytic degradation of Diquat and Paraquat solutions, a basic pH can be determinant, as well as the type of catalyst. The type of catalyst can also strongly influence the degradation pattern of the herbicide. Regarding complete degradation, we were able to show that Diquat is more persistent than Paraquat. During the photocatalytic processes, several intermediate and reaction products are sequentially formed, to which structures are proposed.     

The environmental hazard caused by smelter slags from the Sta. Maria de la Paz mining district in Mexico

The noxious potential of metallurgical tailings from the Ag/Pb/Zn/Cu mining district of Sta. María de la Paz (Mexico) is ascertained via the chemical characterization of slag material. Batch experiments using various extraction solutions (e.g. natural rainwater, water rich in humic substances, ammonium nitrate solution) revealed information on the dissolution behaviour of the elements Fe, Mn, Ni, Cu, Zn, As, Ba and Pb from slag with respect of grain size (slag material screened under 2 mm and analytically fine fraction) and elution time (2, 7.5, 24 and 240 h). An initial ecotoxicological assessment of the results is made and the environmental danger caused by large volumes of slag tailings is discussed.     

Water reuse in industries: analysis of opportunities in the Paraíba do Sul river basin,a case study in Presidente Vargas Plant,Brazil

Environmental Science and Pollution Research - In recent years, the demand for clean water has been growing all over the world despite the different threats posed, including increasing pollution,...     

The Potential of Cleaner Fermentation Processes for Bioplastic Production: A Narrative Review of Polyhydroxyalkanoates (PHA) and Polylactic Acid (PLA)

Journal of Polymers and the Environment - Synthetic plastics generate major problems in landfills after their consumption for occupying high volumes and difficult the decomposition of other organic...