Heavy metals in the New Zealand atmosphere

Publisher Website
Google Scholar
Abstract
The distribution in the atmosphere of some heavy metals, and the flux of these elements to the Earth’s surface, is discussed. The main emphasis is on lead. The global atmospheric emission of lead has been estimated at 449 x 106 kg/yr, mostly from vehicle emissions and metal industries. Anthropogenic sources exceed natural sources by 18 to 1. Since pre-historic times, lead concentration in snow has increased only by a factor of about three in Antarctica, but by a factor of about 200 in Greenland. There is conclusive evidence from the central Pacific that airborne lead is transported over large distances, and that America is a major source. Clean oceanic air in the New Zealand area is considered to deposit about 10 ng Pb/cm2yr, and rain samples contain between 17 and 41 pg Pb/g. A rain sample collected in mid-Tasman, from air with a trajectory over Australia, contained more lead (490 pg Pb/g). Lead content measured in rain in Christchurch (averaging 16.8 μg Pb/litre) is significantly higher. Atmospheric mercury, unlike lead, is found mainly in the vapour phase. The content of mercury in oceanic airflows in the New Zealand area is a little over 1 ng Hg/m3.