APPLICATION OF A TEFLON(TM) DYNAMIC FLUX CHAMBER FOR QUANTIFYING SOILMERCURY FLUX - TESTS AND RESULTS OVER BACKGROUND SOIL

High precision and low blank contamination were achieved with a Teflon (TM) dynamic chamber for measuring soil mercury flux. Using this chamb er, background soil mercury flux averaged between 2 and 7 ng m(-2) h(- 1) over forest soil, and between 12 and 45 ng m(-2) h(-1) over open fi eld soil. Spatial heterogeneity of soil mercury flux at duplicate plot s co-located within 2 m was small but significant, differing by 20-50% . Elevated mercury emission over field soil occurred in the presence o f direct sunlight at the open field sites. Solar radiation, soil tempe rature and soil moisture were all significant factors effecting mercur y emission from soil. Solar radiation affected the reduction of natura lly occurring, inorganic soil mercury compounds to volatile elemental mercury (Hg-o), we estimate that background soil accounts for the gros s emission of similar to 10(9) g yr(-1) of Hg-o to the atmosphere, wit h approximately two-thirds of this total from sunlight-exposed soil an d the remainder from forest and other shaded-soil ecosystems. (C) 1998 Elsevier Science Ltd. All rights reserved.