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This paper presents the results, after a long-term evaluation in marine environments, from an Ibero-American project called "Effect of the environment on reinforcement durability" (DURACON). This project correlates the influence of urban and marine meteorochemical parameters on the performance of reinforced concrete structures in nine countries (Bolivia, Chile, Colombia, Costa Rica, Mexico, Spain, Uruguay, Portugal, and Venezuela). The environment was evaluated using ISO Standard 9223 and the concrete was characterized physically by measuring compressive strength, elastic modulus, total and effective porosity, as well as the effective porosity and resistance to water absorption using the Fagerlund method. To that effect, concrete specimens (with and without reinforcement) were prepared for electrochemical and physical/ mechanical/chemical tests using the existing materials in each participating country, following strict procedures that enabled the preparation of similar concrete specimens. Two water/cement (w/c) ratios (0.45 and 0.65) were selected, where 0.45 w/c ratio concrete had a minimum cement content of 400 kg/m3 and the one with 0.65 w/c ratio had a minimum 28-d compressive strength of 210 kg/cm2. Type I Portland cement, siliceous sand, and crushed rock as coarse aggregates (13-mm maximum nominal size) were used. The results showed that the atmospheric aggressiveness was higher in tropical countries, especially when temperature rises above 25°C, with La Voz station (marine) in Venezuela being the most aggressive. Also, the chloride concentration threshold for rebar depassivation onset was much lower (≈0.42%) in a marine tropical environment, such as La Voz in Venezuela, compared to a nontropical one, such as Cabo Raso in Portugal (≈0.89%), with this concentration dependent on rebar depth and influenced by environmental factors such as time of wetness and ambient temperature, and not only from physical concrete properties. [ABSTRACT FROM AUTHOR]

This project discusses the behavior of a corrosion inhibitor, a water-based mixture of amine's and esters, principally butyl oleate plus amines, for steel in concrete at three different dosages. Each dosage was evaluated in a concrete mix with a water/cement ratio of 0.6. The slabs included Portland cement concrete without inhibitor as the control. Non destructive test of steel reinforced concrete laboratory specimens were used. Specimens containing the manufacture’s recommended dosage (100%) produced significant improvements in corrosion protection compared with the control, the 50% and 125% specimens. However after 400 days all the slabs showed more negative potential values than 350 mV (CSE) meaning a 90% corrosion probability. In general there is a good agreement in the inferences on the corrosion behavior made from each test performed. [ABSTRACT FROM AUTHOR]

An experiment has been designed and performed using Cantaloupe Charentais melon as climacteric fruit with the aim of finding out at which point of their development they are able to sense the plant hormone ethylene. Fruit were harvested at 20, 25, and 35 days after pollination (DAP), treated for 5 days at 20 °C with 5 ppm of ethylene, and stored for a further 10 days. Nontreated wild type fruit was used as control. Ethylene-treated genetically modified 1-aminocyclopropane-1 -carboxylic acid oxidase antisense fruits with inhibited autocatalytic ethylene production were also used to avoid masking effects because of endogenous ethylene produced by control fruits. Ethylene-treated wild type fruits with 25 DAP were able to produce autocatalytic ethylene. A climacteric respiration increase was observed in treated wild type fruit with 25 and 35 DAP. The degreening of the rind was induced by ethylene in the youngest fruit, showing a total dependence on the hormone for its activation. Loss of pulp firmness induced by exogenous ethylene was found only in 20 DAP-fruit. The existence of ethylene-dependent and developmental factors in the regulation .of this ripening process was observed. [ABSTRACT FROM AUTHOR]

A toxicogenomic approach was used for toxicity evaluation of arsenic in the aquatic environment, and differential gene expression was investigated from 24 h and 96 h water-only acute toxicity tests with the aquatic oligochaete, Tubifex tubifex ( Annelida , Clitellata ). Several toxicological endpoints (survival and autotomy) of the oligochaete and tissue residues were measured, and dose-response modelling of gene expression data was studied. A reference transcriptome of the aquatic oligochaete, T. tubifex , was reconstructed for the first time, and genes related to cell stress response ( Hsc70 , Hsp10 , Hsp60 , and Hsp83 ), energy metabolism ( COX1 ), oxidative stress ( Cat , GSR , and MnSOD ), and the genes involved in the homeostasis of organisms ( CaM , RpS13 , and UBE2 ) were identified and characterised. The potential use of the genes identified for risk assessment in freshwater ecosystems as early biomarkers of arsenic toxicity is discussed.

The study was performed on residue-effects datasets from polluted and unpolluted sites in the Nalón River basin (northern Spain). The effects were measured in terms of alteration of field macroinvertebrate communities, and measured as ecological status scores, and number of families and abundance of Ephemeroptera, Plecoptera and Trichoptera (EPT). Non-linear regression models of the field-measured tissue residues in 10 taxa related to the ecological status of the macroinvertebrate communities were used to derive effective tissue residues (ERs). These were estimated for the good/moderate boundary defined by the ecological quality ratio (EQRs) score and for the 50% reduction of EQR and EPT metrics. As, Cu, Hg and Se ERs were calculated for several macroinvertebrate taxa with different feeding styles. The ER dataset allowed us to estimate As and Cu hazardous concentrations (HC), using species sensitivity distribution models, and were interpreted as community thresholds. Further studies for Hg and Se are needed to complete the database required for HC estimation. The reliability and differences of the several thresholds were tested in a risk assessment using a tissue-residue approach (TRA) conducted with field organisms from Cauxa Creek, a tributary from the same basin exposed to high levels of metals in the sediments due to gold mining activities. This risk assessment identified that As and Cu tissue residues satisfactorily explained the reduction in the ecological status of the macroinvertebrate assemblages. Our results indicate that TRA can help in setting future environmental quality standards for the protection of aquatic biota., (© 2022. The Author(s).)

Oligochaetes feed on bulk sediment and penetrate the sediment through the construction of burrows, making them especially vulnerable to sediment metal contamination. However, the few oligochaete species that have been tested to date are almost exclusively temperate test species. Although the warmwater adapted species Branchiura sowerbyi has been indicated as a promising candidate for tropical sediment toxicity testing, few (especially chronic) studies have been conducted so far to confirm this. Therefore, the aim of the present study was to evaluate the bioaccumulation and chronic 28d lethal and sublethal toxicity of arsenic (As) and zinc (Zn) to both the warmwater-adapted B. sowerbyi and the coldwater-adapted oligochaete Tubifex tubifex for comparison. Arsenic was more toxic to both oligochaete species than Zn. Inter- and intra-species variability in toxicity values of the two test species and other benthic invertebrates was within an order of magnitude. However, B. sowerbyi was the most sensitive species to As even for sediment concentration (EC 50 : 36.6 ± 2.1 µg/g and 147.1 ± 21.7 µg/g, for B. sowerbyi and T. tubifex, respectively) and for tissue concentration (ER 50 : 9.2 ± 0.9 µg/g and 887.0 ± 35.0 µg/g, for B. sowerbyi and T. tubifex, respectively). Finally, the Tissue Residue-effects Approach (TRA) using Effective Tissue Residues appears to be a promising way forward in advancing in this since it considers internal body concentrations., (Copyright © 2021. Published by Elsevier B.V.)