In 1989 he obtained a habilitation in environmental protection sciences from Odessa University, with a thesis titled "Mecanismele proceselor eco-chimice în mediu acvatic" ("Mechanisms of ecological chemical processes in the aquatic environment").

Noted for his contributions to the fields of chemistry, physics, and environmental protection, Duca was appointed as chairman of the Republican Committee for Youth Awards in Science and Technology in 1992, a position he still holds.

In 1998, Duca was elected as a deputy (member) in the Parliament of the Republic of Moldova under the Braghiș Alliance—he served as president of the Committee on Culture, Science, Education and Mass Media of the Chişinău legislature until 2001.

In a vote in Parliament on 19 April 2001, Duca was appointed to the Moldovan executive as Minister of Environment, Public Works and Regional Development in the First Tarlev Cabinet.

By decree of the then-President of Moldova, Vladimir Voronin, Duca was appointed an ex officio member of the government, a position he still holds.