| Popis: |
Surface snow from Windless Bight, Ross Ice Shelf, Antarctica has been analyzed for its Hg content. Ultra-clean techniques were used for field extraction of Hg onto gold-coated sand, followed by photo-acoustic analysis within 24 h. Results yield a mean mercury content of 2.7 pg g −1 . However, the true level is probably −1 , as measured amounts decreased throughout the period of sampling, indicating that the first samples were probably contaminated and that later results are likely to be more accurate. Our results suggest that previous studies of Antarctic snow have suffered from major contamination problems. Refinement of techniques should allow historical trends in atmospheric Hg levels to be identified from a snow pit at a suitable remote site. |
