Biosorption of copper, zinc, cadmium and nickel by Chlorella vulgaris

The sorption capacity of the microalga, Chlorella vulgaris, was investigated using different metals (Cu, Zn, Cd and Ni), in both monometallic and bimetallic solutions. The final metal concentrations were significantly low. In the case of copper, an acid pretreatment (at pH 3) of the biomass was required to avoid an excessive increase in pH and the subsequent precipitation of metal during tests. This pretreatment was not necessary for the rest of the metals. The study of the influence of pH led to a greater metal uptake at a higher pH, suggesting a clear competition between metal cations and protons during the biosorption process. The biomass concentration was also a relevant variable, and the best sorption capacities were achieved at the lowest biomass concentration. pH also had a great influence on the elution of the metal retained by the biomass. The best recovery yields were obtained for the lower pH of the eluent solution. Sorption isotherms were well fitted to the Langmuir model, for both single-metal and two-metal systems. In both cases, the biomass showed a greater affinity for Cd.     

Particulate matter in the indoor and outdoor air of a gymnasium and a fronton

An indoor/outdoor monitoring programme of PM₁₀ was carried out in two sports venues (a fronton and a gymnasium). Levels always below 50 μg m^?3 were obtained in the fronton and outdoor air. Due to the climbing chalk and the constant process of resuspension, concentrations above 150 μg m^?3 were registered in the gymnasium. The chalk dust contributed to CO₃ ^2? concentrations of 32?±?9.4 μg m^?3 in this sports facility, which represented, on average, 18 % of the PM₁₀ mass. Here, the carbonate levels were 128 times higher than those registered outdoors. Much lower concentrations, around 1 μg m^?3, were measured in the fronton. The chalk dust is also responsible for the high Mg²⁺ concentrations in the gym (4.7?±?0.89 μg m^?3), unfolding a PM₁₀ mass fraction of 2.7 %. Total carbon accounted for almost 30 % of PM₁₀ in both indoor spaces. Aerosol size distributions were bimodal and revealed a clear dependence on physical activities and characteristics of the sports facilities. The use of climbing chalk in the gymnasium contributed significantly to the coarse mode. The average geometric mean diameter, geometric standard deviation and total number of coarse particles were 0.77 μm, 2.79 cm^?3 and 28 cm^?3, respectively.     

Nitrogen oxides and ozone in Portugal: trends and ozone estimation in an urban and a rural site

Environmental Science and Pollution Research - This study provides an analysis of the spatial distribution and trends of NO, NO2 and O3 concentrations in Portugal between 1995 and 2010....     

Lead,copper and zinc in atmospheric and fluvial particulates from the Caracas Valley,Venezuela

The atmospheric particulates from the Caracus Valley in Venezuela and the fluvial particulates transported by the Tuy River into the Caribbean sea have been evaluated for Pb, Cu and Zn with the purpose of determining the contamination levels in the study area. The atmospheric particulate samples were collected in the city of Caracas using a low volume sampler whereas the fluvial particulate were collected at the mouth of the Tuy River. The particulate samples were analysed by flame or graphite furnace atomic absorption spectrometry depending upon the concentration levels of the heavy metal under study. The results obtained for the fluvial particulates enabled estimates to be made of the total anthropogenic flux of Cu (383 ton year^–1), Pb (528 ton year^–1) and Zn (865 ton year^–1). These results yield annual per capita inputs for Cu (96 g),Pb (132 g) and Zn (216 g) which greatly exceed those from global anthropogenic emissions. The weighted average concentration of Pb (1.13 %) found in the atmospheric particulates was much higher than those for Cu (140 mg kg^–1) and Zn (200 mg kg^–1) and reflects the high motor car traffic in the Caracas Valley. The anthropogenic/natural ratios estimated in this study were as follows: 2.6 for Pb; 1.5 for Cu and 1.5 for Zn. This indicates that anthropogenic inputs for Cu, Pb, and Zn in the study area exceed those from natural sources, cars being the major source for Pb and industrial activities the major sources for Cu and Zn.