They also have been linked to the presence of liquid water.

VOA: special.2010.07.28

So iron left to own devices in the atmosphere in the presence of a little bit of water, with the water form iron oxide.

铁在大气中，在存在,少量水的条件下，大气会开始与水结合产生氧化铁。

麻省理工公开课 - 热力学与动力学课程节选

From what we can tell, other than one fire engine distributing water, there's really no presence of any government or other internationalaid groups here.

VOA: standard.2010.01.14