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Sci Total Environ ; 714: 136891, 2020 Jan 23.
Artículo en Inglés | MEDLINE | ID: mdl-32018998


Hydrogen fluoride (HF) is one of the most toxic gaseous compounds in air, the primary anthropogenic source of which is industrial activity, specifically fertilizer and waste. HF concentrations in an urban area (Huelva, SW Spain) related to a nearby major phosphogypsum (PG) deposit were measured by passive sampling during summer and winter months from 2014 to 2017 and high-resolution sampling during 2017 and 2017-2018 using an HF analyser. An HF geochemical anomaly was found in the PG pond with average concentrations of up to 19.1 µg/m3, and concentrations of up to 1.6 µg/m3 were exhibited in the nearest urban area. The concentrations were associated with the HF emissions from the PG deposit. Emission factors were calculated by field and laboratory experiments, and the brines exhibited the highest emission factor (2.7 kg/ha day). Several impacts of HF (>0.1 µg/m3) in the city were recorded throughout the year, occurring at noon in the summer and during fog events in the winter. Consequently, the PG system should be restored to protect the population living in Huelva from the impacts of HF emission.

J Environ Manage ; 254: 109832, 2020 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-31733480


The chemical evolution of brines resulting from an inactive phosphogypsum pond derived of fertilizer industry located in Huelva (Spain, SW Europe) has been studied based on a weekly sampling from 2014 to 2017. Long-range time variation of metals and ions concentrations in brines are expected to depend on environmental parameters such as rainfall and evaporation. The results show that brines are enriched in F- (1.7-2.0 g/l), Cl- (13-24 g/l), SO42- (7.2-9.3 g/l), V (70-128 mg/l) and U (55-98 mg/l). A great variation of chemical concentrations has been found, due to dilution, recharge and evaporation processes. Most of the elements show peak concentrations in summer, coinciding with the lowest pH values (<1), high conductivity (>133 mS/cm), and high evaporation rates as expected. Nonetheless, F- shows an opposite behaviour, varying its concentrations between 0.9 g/l in summer and 3.7 g/l in the rainy season. According to the results, a future restoration plan for PG ponds should include the removal of brines and layered salts during summer in order to avoid the annual generation of brines and their impact on the environment.

Estanques , Contaminantes Químicos del Agua , Sulfato de Calcio , Europa (Continente) , Fósforo , Sales (Química) , España
J Colloid Interface Sci ; 264(1): 114-20, 2003 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-12885527


The influence of CO on the passive behavior of copper was analyzed in the potential region near the rest potential in borax solutions (pH 9.2) by cyclic voltammetry, ellipsometry, and surface charge determination techniques. The oxide formation is explained as a sequence of Cu(2)O growth, cation adsorption, Cu(II), and dissolution steps, similarly to previously reported investigations for the metal in free CO solutions. The CO adsorption hinders the cationic defect in the outer oxide layer and accelerates the Cu(2)O growth both at open circuit and in controlled potential experiments. The isoelectric point, iep, obtained at pH 10.8 for both the metal Cu and CuO particles in KCl solutions shifts to pH 10.1 for copper particles in the presence of CO. The iep indicates a CuO coating on Cu metallic particles in the absence of CO.