Sentence:  Thus, for the remaining elements, including oxygen, the solid phase appears to be important. In fact, at a metallicity of Z=0.02, and with a gas-to-dust ratio of 100, about half of the <WSD>metals</WSD> — including oxygen — are contained in the solid phase. 
Meaning of the word marked with <WSD> tags:  An element which was not directly created after the Big Bang but instead formed through nuclear reactions; any element other than hydrogen and helium.