Sonophotocatalytic degradation of alazine and gesaprim commercial herbicides in TiO2 slurry

The photocatalytic degradation of alazine and gesaprim commercial herbicides was carried out in aqueous TiO(2) suspensions under UV light (15W, 352 nm). Degradation of these herbicides was also observed by the combined effects of photocatalysis with sonolysis (sonophotocatalysis) using an ultrasound source of 20kHz. Degradation profiles were recorded by measuring the concentration of the active compounds present in the alazine (alachlor and atrazine) and gesaprim (atrazine) by HPLC as a function of irradiation time (sound and/or light). Over 90% of the active component in the gesaprim was abated and those in alazine were completely degraded. The content of total organic carbon and chemical oxygen demand was also monitored. Mineralization of the commercial herbicides was achieved. Over 80% of chemical oxygen demand abatement was attained for both herbicides with sonophotocatalysis at 150 min of irradiation time. The photocatalytic degradation of the herbicides followed a pseudo-first order kinetics and their rate constant was increased by the combined effects of sonolysis.     

The influence of Sarcocornia fruticosa on retention of PAHs in salt marsh sediments (Sado estuary, Portugal)

Depth concentration profiles of PAHs, organic carbon and dissolved oxygen in non-colonised sediments and sediments colonised by Sarcocornia fruticosa from Mitrena salt marsh (Sado, Portugal) were determined in November 2004 and April 2005. Belowground biomass and PAH levels in below and aboveground material were also determined. In both periods, colonised sediments were oxygenated until 15-cm, rich in organic carbon (max 4.4%) and presented much higher PAH concentrations (max. 7.1 microg g(-1)) than non-colonised sediments (max. 0.55 microg g(-1)). Rooting sediments contained the highest PAH concentrations. The five- and six-ring compounds accounted to 50-75% of the total PAHs in colonised sediments, while only to 30% in non-colonised sediments. The elevated concentrations of PAHs in colonised sediments may be attributed to the transfer of dissolved PAH compounds towards the roots as plant uptake water and subsequent sequestration onto organically rich particles. A phase-partitioning mechanism probably explains the higher retention of the heavier PAHs. In addition oxygenated conditions of the rooting sediments favour the degradation of the lighter PAHs and explain the elevated proportion of the heavier compounds. Below and aboveground materials presented lower PAH concentrations (0.18-0.38 microg g(-1)) than colonised sediments. Only 3- and 4-PAHs were quantified in aboveground material, reflecting either preferential translocation of lighter compounds from roots or atmospheric deposition.     

Characterization of municipal solid waste from the main landfills of Havana city

The city of Havana, the political, administrative and cultural centre of Cuba, is also the centre of many of the economic activities of the nation: industries, services, scientific research and tourism. All of these activities contribute to the generation of municipal solid waste (MSW), which also impact other Cuban cities. Inadequate handling of waste and the lack of appropriate and efficient solutions for its final disposal and treatment increase the risk and possibility of contamination. The main difficulty in the development of a system of management of MSW lies in the lack of knowledge of the chemical composition of the waste that is generated in the country as a whole, and especially in Havana, where solid waste management decisions are made. The present study characterizes MSW in Havana city during 2004. The Calle 100, Guanabacoa and Ocho Vías landfills were selected for physical-chemical characterization of MSW, as they are the three biggest landfills in the city. A total of 16 indicators were measured, and weather conditions were recorded. As a result, the necessary information regarding the physical-chemical composition of the MSW became available for the first time in Cuba. The information is essential for making decisions regarding the management of waste and constitutes a valuable contribution to the Study on Integrated Management Plan of MSW in Havana.     

Spectroscopic changes on fulvic acids from a kraft pulp mill effluent caused by sun irradiation

Large volumes of wastewater with a high organic load are generated by the pulp and paper industry that negatively affect the quality of receiving waters. The main waste products in the pulp mill effluents are lignin derived macromolecular compounds, which are similar to natural humic substances and very resistant to wastewater treatments. Fulvic acids (FA) represent the higher percentage of these humic substances and it was observed that solar irradiation modify their properties. Several analytic tools, namely, UV–Visible, molecular fluorescence and FTIR spectroscopies, were used to assess the effect of solar exposition on fulvic acids from a kraft pulp mill effluent. It may be concluded that sun irradiation may alter to a high extent the physicochemical properties of macromolecular organic matter, namely fulvic acids, released by kraft pulp mill effluents. After solar exposition, the aromaticity decreases, the aliphatic structures become more oxygenated, and the fulvic acids from the pulp mill effluent remaining in solution are more similar to aquatic fulvic acids from non polluted sites.     

Chemical characterisation of particulate matter in urban transport modes

Traffic is a main source of air pollutants in urban areas and consequently daily peak exposures tend to occur during commuting. Personal exposure to particulate matter (PM) was monitored while cycling and travelling by bus, car and metro along an assigned route in Lisbon (Portugal), focusing on PM2.5 and PM10 (PM with aerodynamic diameter <2.5 and 10 µm, respectively) mass concentrations and their chemical composition. In vehicles, the indoor-outdoor interplay was also evaluated. The PM2.5 mean concentrations were 28?±?5, 31?±?9, 34?±?9 and 38?±?21?µg/m³ for bus, bicycle, car and metro modes, respectively. Black carbon concentrations when travelling by car were 1.4 to 2.0 times higher than in the other transport modes due to the closer proximity to exhaust emissions. There are marked differences in PM chemical composition depending on transport mode. In particular, Fe was the most abundant component of metro PM, derived from abrasion of rail-wheel-brake interfaces. Enhanced concentrations of Zn and Cu in cars and buses were related with brake and tyre wear particles, which can penetrate into the vehicles. In the motorised transport modes, Fe, Zn, Cu, Ni and K were correlated, evidencing their common traffic-related source. On average, the highest inhaled dose of PM2.5 was observed while cycling (55 µg), and the lowest in car travels (17 µg). Cyclists inhaled higher doses of PM2.5 due to both higher inhalation rates and longer journey times, with a clear enrichment in mineral elements. The presented results evidence the importance of considering the transport mode in exposure assessment studies.     

Evaluation of the toxicity of two soils from Jales Mine (Portugal) using aquatic bioassays

Soil contamination can be one path for streams and groundwater contamination. As a complement of chemical analysis and total contaminants determination, bioassays can provide information on the bioavailable fraction of chemical compounds, focusing on the retention and habitat function of soils. In this study the evaluation of the toxicity of two soils from the abandoned Jales Mine (Portugal) regarded both functions. The buffer capacity of soils was tested with bioassays carried out using the cladoceran Daphnia magna and the marine bacteria Vibrio fischeri. The habitat function of soils was evaluated with the reproduction bioassay with the collembolan Folsomia candida. The Microtox solid-phase test was performed with V. fischeri using soil as test medium, and soil elutriates were extracted to perform the Microtox basic test, and an immobilization and reproduction bioassay with D. magna. The marine bacteria showed high sensitivity to the soil with low heavy metal content (JNC soil) and to JNC soil elutriates, while the soil with highest heavy metal content (JC soil) or soil elutriates exposure did not cause any toxic effect. In the bioassays with D. magna, organisms showed sensitivity to JNC and also to JC soil elutriates. Both mobilization and reproduction features were inhibited. The bioassay with F. candida did not reflect any influence of the contaminants on their reproduction. Although JNC soil presented lower heavy metal contents, elutriates showed different patterns of contamination when compared to JC soil and elutriates, which indicates different retention and buffer capacities between soils. Results obtained in this study underlined the sensitivity and importance of soil elutriate bioassays with aquatic organisms in the evaluation strategy in soil ERA processes.     

The immobilisation and retention of soluble arsenic, cadmium and zinc by biochar

Water-soluble inorganic pollutants may constitute an environmental toxicity problem if their movement through soils and potential transfer to plants or groundwater is not arrested. The capability of biochar to immobilise and retain arsenic (As), cadmium (Cd) and zinc (Zn) from a multi-element contaminated sediment-derived soil was explored by a column leaching experiment and scanning electron microanalysis (SEM/EDX). Sorption of Cd and Zn to biochar’s surfaces assisted a 300 and 45-fold reduction in their leachate concentrations, respectively. Retention of both metals was not affected by considerable leaching of water-soluble carbon from biochar, and could not be reversed following subsequent leaching of the sorbant biochar with water at pH 5.5. Weakly water-soluble As was also retained on biochar’s surface but leachate concentrations did not duly decline. It is concluded that biochar can rapidly reduce the mobility of selected contaminants in this polluted soil system, with especially encouraging results for Cd.     

Production of zeolitic materials in pilot scale based on coal ash for phosphate and potassium adsorption in order to obtain fertilizer

Environmental Science and Pollution Research - The use of different types of zeolites (X, Na-P1, and 4A) synthesized by different methods and scales were tested in this work to adsorb nutrients...     

Energy and environment as the foundations for sustainable development

Environmental Science and Pollution Research -