Friulian language
Merkù was an honorary member of the Slavic Society of Slovenia, and in 2007 he received its recognition for his lifetime achievement in research on Slovene along the language's western border. In the decision conferring the award, Alenka Šivic Dular wrote that Merkù's linguistic studies especially emphasized "research on personal names and toponyms in the Trieste, Gorizia, and Venetian Slovenia areas and drew attention to traces of Slovene-Friulian language contact ("Slovenski priimki na zahodni meji", Slovene Surnames on the Western Border, 1982; "La toponomastica del Comune di Duino-Aurisina", Toponyms in the Commune of Duino-Aurisina, 1989; "La toponomastica dell'Alta val Torre", Toponyms in the Upper Torre Valley, 1997; "1300 primorskih priimkov", 1,300 Littoral Surnames, 2004; "Krajevno imenoslovje na slovenskem zahodu", Regional Onomastics in Western Slovene Territory, 2006). Some of Merkù's books are seminal works, and his creativity and confident approach mark the Slovene physical and cultural presence in Trieste."