the journey will take around ten days ,这个句子里around短语在句子里充当什么

take是及物动词,后面作宾语的是名词短语around ten days,ten days前加限定副词around相当于about ten days.
例如：
I'll be back at around 5 o'clock.
五点左右我就回来.
介词短语at around 5 o'clock中around明显不是介词,而是副词,修饰名词短语 5 o'clock,“大约”的意思.
副词修饰名词其实很常见,如The people there were very friendly.那儿的人很友好.在这里there 作定语,修饰The people.
但在这里似乎没有必要纠缠这个副词around的成分,知道整个around ten days是名词短语作宾语就行了.
仅供参考.

这里应该是副词不是介词。