Abiotic factors driving cyanobacterial biomass and composition under perennial bloom conditions in tropical latitudes

Hydrobiologia - While warming and eutrophication have increased the frequency and magnitude of harmful cyanobacterial blooms globally, the scenario for many eutrophic tropical freshwaters is a...     

Resistance of Cyanobacterial Fouling on Architectural Paint Films to Cleaning by Water Jet

Mortar panels painted with three different white acrylic coatings were exposed to the environment in urban (São Paulo) and rural (Pirassununga) sites in Brazil for 7 years. After this time, all panels were almost equally discoloured, and paint detachment was observed to only a small degree. The biofilms were composed mainly of cyanobacteria and filamentous fungi, principal genera being Gloeocapsa and Chroococcidiopsis of the cyanobacteria, and Cladosporium and Alternaria of the fungi. Two of the three paints in Pirassununga became covered by a pink film that contained red-encapsulated Gloeocapsa and clay particles. The third, an 800% elastomeric matt formulation, became discoloured with a grey, only slightly pink, film, although the same cyanobacteria were present. The levels of paint detachments from all films in both locations were low, with rating range of 0–1 of a maximum 5 (100% detachment). After high-pressure water jetting, paint detachments increased at both locations, up to 2 in Pirassununga and 3 in São Paulo. Discoloration decreased; L*A*B* analysis of surface discoloration showed that ΔE (alteration in colour from the original paint film) changed from 28–39 before cleaning to 13–16 afterwards. The pink coloration was not entirely removed from Pirassununga samples, suggesting that cyanobacterial cells are difficult to detach, and microscopic analysis of the biofilms confirmed that Gloeocapsa was still present as the principal contaminant on all surfaces, with Chroococcidiopsis being present as the second most common. Almost no fungi were detected after water jet application.     

Material flow analysis and material use efficiency of Brazil's mortar and concrete supply chain

Cementitious materials, mostly concrete and mortar, account for about one‐third of all materials extraction worldwide. Material flow data in this industry are still unsatisfactory, especially related to unused extraction materials, quarry wastes, and water consumption, aspects which usually are not included in environmental analysis studies. The aim of this study is to conduct a material flow analysis (MFA) of the Brazilian concrete and mortar supply chain to quantify material use efficiency (ME) and dematerialization potential. The MFA includes extraction, production, and construction stages for the following indicators: i) unused extraction; ii) quarry waste; iii) water consumption; iv) material wastage; v) raw material consumption; vi) energy carriers; and vii) atmospheric emissions. The results demonstrated that the primary raw material footprint is about 456 million metric tons (Mt) corresponding to a metabolic rate of 2.2 metric tons/capita (t/capita). After including unused extraction, quarry wastes, water consumption, and secondary materials this value increases to 4.1 t/capita corresponding to a total material consumption of 840 Mt. Concrete and mortar can be produced using two routes—mixing on site or industrial mixing. We conclude that the industrial scenario allows for dematerialization by about 8% for concrete and 24% for mortar, by mass; and the average material use efficiency is low, at about 53% for concrete and 34% for mortar.