Sanchez-Hernandez J C
Department of Environmental Biology, University of Siena, Italy.
Rev Environ Contam Toxicol. 2000;166:83-127.
Data concerning trace element concentrations in both abiotic and biotic components of the Antarctic ecosystems are summarized here to be used as a first background database for pollution detection. Antarctic ancient ice and snow cores have been used to assess past and present-day changes in global atmospheric levels of certain trace elements. Concentrations of Pb, Cd, and Hg in the Antarctic tropospheric cell have varied according to glacial and interglacial periods before humans began to contaminate the atmosphere with these metals. Based on data of Pb concentrations in the Antarctic ancient ice cores and samples of recent snow, most of the Pb in Antarctica is anthropogenic. Moreover, this metal has decreased in recent years as a consequence of the reduced use of leaded gasoline in countries of the Southern Hemisphere. Reliable experimental and field data have indicated, however, that human activity in Antarctica contributes significantly to increasing atmospheric Pb levels in this continent, whereas the environmental impact of other metals such as Cd, Zn, or Hg is restricted to the area a few hundreds of meters about the anthropogenic source. Trace element concentrations in Antarctic abiotic matrixes are generally at ultratrace levels, challenging analytical detection limits and increasing the risk of unwanted contamination. Pb and Hg concentrations in Antarctic snow, surficial soil, air, and marine sediment have been considered as the lowest concentrations ever reported. Conversely, concentrations in Antarctic biota, are comparable to those from polar and temperate areas of the Northern Hemisphere, in particular Cd and Hg. Environmental and biological factors favoring a greater metal accumulation by Antarctic biota are discussed. Growth rate of the organisms and detoxification mechanisms (e.g., metallothioneins, molting cycles) are largely affected by the extreme environmental conditions in Antarctica (water supply, temperature regimen, light availability) that probably interfere with uptake, storage, and excretion of trace elements by organisms. On the other hand, environmental factors such as the upwelling of Cd-rich waters and local volcanism undoubtedly increase the bioavailability of metals in the Antarctic environment. In this context, several Antarctic organisms such as fish, mollusks, lichens, and mosses have been proposed as suitable biomonitors, and their trace element concentrations have been suggested as baselines. Structure and dynamics of Antarctic ecosystems as well as quantifying metal point sources and long-range atmospheric transport require in-depth studies to improve the assessment of human impact in Antarctica.
本文总结了南极生态系统中非生物和生物成分中微量元素浓度的数据，用作污染检测的首个背景数据库。南极古冰芯和雪芯已被用于评估全球大气中某些微量元素过去和当前的变化。在人类开始用这些金属污染大气之前，南极对流层中铅、镉和汞的浓度随冰川期和间冰期而变化。根据南极古冰芯中铅浓度的数据以及近期雪样，南极的大部分铅是人为来源。此外，由于南半球国家减少了含铅汽油的使用，近年来这种金属的含量有所下降。然而，可靠的实验和实地数据表明，人类在南极的活动显著导致了该大陆大气中铅含量的增加，而镉、锌或汞等其他金属对环境的影响仅限于人为源周围几百米的区域。南极非生物基质中的微量元素浓度通常处于超痕量水平，这对分析检测限构成挑战，并增加了意外污染的风险。南极雪、表层土壤、空气和海洋沉积物中的铅和汞浓度被认为是有记录以来的最低浓度。相反，南极生物群中的浓度与北半球极地和温带地区的浓度相当，特别是镉和汞。文中讨论了有利于南极生物群积累更多金属的环境和生物因素。生物体的生长速度和解毒机制（如金属硫蛋白、蜕皮周期）在很大程度上受到南极极端环境条件（供水、温度状况、光照可用性）的影响，这些条件可能会干扰生物体对微量元素的吸收、储存和排泄。另一方面，诸如富含镉的海水上涌和局部火山活动等环境因素无疑增加了南极环境中金属的生物可利用性。在这种背景下，几种南极生物，如鱼类、软体动物、地衣和苔藓，已被提议作为合适的生物监测器，其微量元素浓度被建议作为基线。南极生态系统的结构和动态以及量化金属点源和大气长距离传输需要深入研究，以改进对人类在南极影响的评估。
