ABSTRACT
Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 - beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20(th) century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19(th) century and remains a significant source today. An estimated 660â t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21(st) century.
Subject(s)
Environmental Pollution/analysis , Ice/analysis , Lead/analysis , Water Pollutants, Chemical/analysis , Antarctic Regions , Ecosystem , Environmental Pollution/history , History, 19th Century , History, 20th Century , History, 21st Century , HumansABSTRACT
Nearly three decades of stable isotope ratios and surface mass balance (SMB) data from eight shallow firn cores retrieved at Fimbul Ice Shelf, East Antarctica, in the Austral summers 2009-2011 have been investigated. An additional longer core drilled in 2000/2001 extends the series back to the early eighteenth century. Isotope ratios and SMB from the stacked record of all cores were also related to instrumental temperature data from Neumayer Station on Ekström Ice Shelf. Since the second half of the twentieth century, the SMB shows a statistically significant negative trend, whereas the δ18O of the cores shows a significant positive trend. No trend is found in air temperature at the nearest suitable weather station, Neumayer (available since 1981). This does not correspond to the statistically significant positive trend in Southern Annular Mode (SAM) index, which is usually associated with a cooling of East Antarctica. SAM index and SMB are negatively correlated, which might be explained by a decrease in meridional exchange of energy and moisture leading to lower precipitation amounts. Future monitoring of climate change on the sensitive Antarctic ice shelves is necessary to assess its consequences for sea level change. KEY POINTS: Mass balance and stable oxygen isotope ratios from shallow firn coresDecreasing trend in surface mass balance, no trend in stable isotopesNegative correlation between SAM and SMB.
ABSTRACT
A total of 93 patients with pulmonary diseases were examined by means of magnetic resonance tomography. Of these, 39 had a bronchial neoplasm of varying histological structure and varying hilar and mediastinal extension. Compared with other imaging methods, magnetic resonance tomography offers advantages in the imaging of a malignant process and accurate definition of its spatial extension. MR and CT seem to be essentially of equal value in respect of the diagnostic problem of deciding whether lymph node metastases are present in the mediastinum and in the hilus. On the other hand, CT is presently still superior to MR with regard to verifying small-scale processes which are in the process of undergoing endobronchial growth, since CT provides better spatial resolution. Hence, in our opinion the special value of magnetic resonance tomography is the exact definition of the extension of an already identified neoplastic process. This method can supply accurate pointers towards the operability of a bronchial neoplasm. In this regard it is an ideal complement to mediastinoscopy. However, MR will not be an important tool--even in the foreseeable future--for effecting early diagnosis of a neoplasm. The value of diagnostic information supplied by this method may improve by the future use of breath triggering, and additional diagnostic advantages are envisaged by the use of contrast media and the future possibility of producing thinner layers. That is why the catalogue of indications prepared at this time should be seen as a kind of momentary snapshot which may have to be supplemented or extended after the prevailing technical and equipment parameters have undergone further optimisation.
