Jagoe C H, Arnold-Hill B, Yanochko G M, Winger P V, Brisbin I L
University of Georgia, Savannah River Ecology Laboratory, Aiken, SC 29802, USA.
Sci Total Environ. 1998 Jun 10;213(1-3):255-62. doi: 10.1016/s0048-9697(98)00098-9.
Mercury methylation may be enhanced in wetlands and humic-rich, blackwater systems that crocodiles and alligators typically inhabit. Given their high trophic level and long life-spans, crocodilians could accumulate significant burdens of Hg. Our objectives were to survey Hg concentrations in alligators from several areas in the southeastern United States to test their utility as sentinels of Hg contamination, to examine relationships among Hg concentrations in various tissues and to look for any differences in tissue Hg concentrations among locations. We measured total Hg concentrations in alligators collected in the Florida Everglades (n = 18), the Okefenokee National Wildlife Refuge, Georgia (n = 9), the Savannah River Site (SRS), South Carolina (n = 49) and various locations in central Florida (n = 21), sampling tissues including blood, brain, liver, kidney, muscle, bone, fat, spleen, claws and dermal scutes. Alligators from the Everglades were mostly juvenile, but Hg concentrations in tissues were high (means: liver 41.0, kidney 36.4, muscle 5.6 mg Hg/kg dry wt.). Concentrations in alligators from other locations in Florida were lower (means: liver 14.6, kidney 12.6, muscle 1.8 mg Hg/kg dry wt.), although they tended to be larger adults. Alligators from the Okefenokee were smallest and had the lowest Hg concentrations (means: liver 4.3, kidney 4.8, muscle 0.8 mg Hg/kg dry wt.). SRS alligators had the greatest size range and intermediate Hg levels (means: liver 14.9, muscle 4.8 mg Hg/kg dry wt.). At some locations, alligator length was correlated with Hg concentrations in some internal organs. However, at three of the four locations, muscle Hg was not related to length. Tissue Hg concentrations were correlated at most locations however, claw or dermal scute Hg explained less than 74% of the variation of Hg in muscle or organs, suggesting readily-obtained tissues, such as scutes or claws, have limited value for non-destructive screening of Hg in alligator populations.
在鳄鱼和短吻鳄通常栖息的湿地以及富含腐殖质的黑水系统中，汞的甲基化作用可能会增强。鉴于它们处于较高的营养级且寿命较长，鳄目动物可能会积累大量的汞。我们的目标是调查美国东南部几个地区短吻鳄体内的汞浓度，以测试它们作为汞污染指示生物的效用，研究不同组织中汞浓度之间的关系，并寻找不同地点之间组织汞浓度的差异。我们测量了在佛罗里达大沼泽地（n = 18）、佐治亚州奥克弗诺基国家野生动物保护区（n = 9）、南卡罗来纳州萨凡纳河 Site（SRS）（n = 49）以及佛罗里达州中部不同地点（n = 21）采集的短吻鳄体内的总汞浓度，所采集的组织包括血液、大脑、肝脏、肾脏、肌肉、骨骼、脂肪、脾脏、爪子和皮盾。来自大沼泽地的短吻鳄大多为幼体，但组织中的汞浓度很高（平均值：肝脏 41.0、肾脏 36.4、肌肉 5.6 毫克汞/千克干重）。来自佛罗里达州其他地点的短吻鳄汞浓度较低（平均值：肝脏 14.6、肾脏 12.6、肌肉 1.8 毫克汞/千克干重），不过它们往往是体型较大的成年个体。来自奥克弗诺基的短吻鳄体型最小，汞浓度也最低（平均值：肝脏 4.3、肾脏 4.8、肌肉 0.8 毫克汞/千克干重）。SRS 的短吻鳄体型范围最大，汞含量处于中等水平（平均值：肝脏 14.9、肌肉 4.8 毫克汞/千克干重）。在一些地点，短吻鳄的体长与某些内脏器官中的汞浓度相关。然而，在四个地点中的三个，肌肉中的汞与体长无关。大多数地点的组织汞浓度之间存在相关性，但是爪子或皮盾中的汞只能解释肌肉或器官中汞变化的不到 74%，这表明像皮盾或爪子这样容易获取的组织，对于短吻鳄种群中汞的非破坏性筛查价值有限。
