Biogeochemical Fluxes of Zinc

Biogeochemical Fluxes of Zinc Zinc in plant-soil system 

Zinc exchange between plant canopy and ground level troposphere is also responsible for the input of this trace metal to the air pool. One square meter of the canopy may annually exude up to 9 kg of Zn as a terpene component (Beaufort et al, 1975). During bacterial biometallization in sub-aquatic coastal areas, the formation and corresponding volatilization of organozinc species take place however, at present there is no quantitative parameterization of these processes in regional or global scale. 

Sedimcmary rock Zn content, ppm Zinc mass, lO tons 

In the background atmosphere over land area, the zinc concentration is between 2 and 70ng/m- (Ostromogilsky et al, 1981). A certain amount of zinc is supplied to the atmosphere in mineral dust. The average Zn content in soil is about 50 ppm (see box 3). This gives the estimate of Zn air transport of 0.3 x lO tons/year, of which about 0.1 X 10 tons can be precipitated over the ocean and the remaining can be deposited over the global land (Dobrovolsky, 1994). 

The monitored rainfall Zn content over background areas is between 10 and 40/zg/L, and in polluted areas these values are much higher. Giving the average content as 20/zg/L, Dobrovolsky (1994) estimated the global deposition flux as much as 2.3 X 10 tons/year. 

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Describe the biogeochemical fluxes of zinc in various soil-plant systems of the World. Present the quantitative estimates of these fluxes. 

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