Dolmakalemin mürekkebi azalmış; kalemi temizleyip yeniden doldurdum.

The fountain pen’s ink was low; I cleaned the pen and refilled it.

Breakdown of Dolmakalemin mürekkebi azalmış; kalemi temizleyip yeniden doldurdum.

• kalem: the pen
• temizlemek: to clean
• yeniden: again
• doldurmak: to fill

Questions & Answers about Dolmakalemin mürekkebi azalmış; kalemi temizleyip yeniden doldurdum.

What does the structure Dolmakalemin mürekkebi mean grammatically?

It’s a genitive–possessive chain:

• dolmakalem-in = fountain pen + genitive “of the fountain pen”
• mürekkep-(s)i = ink + 3rd person possessive “its ink” Together: “the fountain pen’s ink.”

Why does mürekkebi end with -i? Is that the accusative?

Here -i is the 3rd person possessive suffix, not the accusative. The subject is the whole phrase Dolmakalemin mürekkebi. If it were accusative, you’d see mürekkebini (possessive -i plus accusative -(n)i). Note the consonant softening: mürekkep → mürekkebi when a vowel-initial suffix is added (p → b).

Could dolmakalemin mean “your fountain pen”?

Alone, kalemin can mean either “of the pen” (genitive) or “your pen” (2sg possessive). In this chain, it’s genitive: “of the fountain pen.”
To say “your fountain pen’s ink,” you’d mark both possession and genitive: senin dolma kaleminin mürekkebi (note the double -in in kaleminin).

Why use azalmış instead of azaldı?