Joan Roca i Caball Joan Roca i Caball Joan Baptista Roca i Caball (1898–1976) was a Catalan Carlist and Christian-Democratic politician. He is known as co-founder of Unió Democràtica de Catalunya and recognized as representative of a "Third Spain", the group which emerged during the Spanish Civil War and claimed to have stood in-between the warring factions. He is also counted among leaders of the Catalan opposition to Francoism. The Roca family has traditionally owned vineyards in the Barcelona province; heavily hit by the phylloxera plague in the mid-19th century, it was driven out of business. Joan's paternal grandfather, Antonio Roca Calvet (1840-1917), inherited
Mercury in fish plant emissions. Chlorine chemical plants use mercury to extract chlorine from salt, which in many parts of the world is discharged as mercury compounds in waste water, though this process has been largely replaced by the more economically viable membrane cell process, which does not use mercury. Coal contains mercury as a natural contaminant. When it is fired for electricity generation, the mercury is released as smoke into the atmosphere. Most of this mercury pollution can be eliminated if pollution-control devices are installed. Mercury in the United States frequently comes from power plants, which release about 50% of the nation's