NOAA/WDS Paleoclimatology - Avery Lake, Illinois 3,200 Year Sediment Lead Isotope Data

The presence and sources of pre-Columbian (before 1492 CE) lead (Pb) pollution in the midcontinental United States were investigated using geochemical and Pb isotope analyses on sediment cores recovered from Avery Lake, a floodplain lake located directly adjacent to the Kincaid Mounds archaeological site on the lower Ohio River, Illinois. Geochemical results indicate the presence of Pb pollution during the Baumer (300 BCE to 300 CE) and Mississippian (1150-1450 CE) occupations, and since the 1800s. Pb isotope results link Mississippian Pb pollution to the processing and use of galena primarily from southeastern and/or central Missouri, and to a lesser extent the upper Mississippi River valley, with ~1.5 t (metric tons) of galena-derived Pb deposited in Avery Lake during this time. Pb pollution during the Baumer phase, equating to ~0.4 t of Pb, was not accompanied by a Pb isotope excursion and most likely originated from local biomass burning. These results provide new information about the environmental impacts associated with pre-Columbian Native Americans' interaction with and utilization of their landscape and its resources.

本研究针对美国中部大陆地区哥伦布发现美洲前（公元1492年之前）的铅（Pb）污染存在情况与污染来源展开探究，通过对伊利诺伊州俄亥俄河下游金凯德土墩（Kincaid Mounds）考古遗址紧邻的漫滩湖埃弗里湖（Avery Lake）所获取的沉积物岩芯开展地球化学与铅同位素分析，完成相关研究工作。地球化学分析结果显示，在鲍默文化期（Baumer，公元前300年至公元300年）、密西西比文化期（Mississippian，公元1150年至1450年）以及19世纪以来的人类活动阶段均存在铅污染现象。铅同位素分析结果表明，密西西比文化期的铅污染主要与来自密苏里州东南部及/或中部的方铅矿（galena）加工与使用有关，少量源自密西西比河上游河谷；该时期埃弗里湖中沉积的方铅矿衍生铅约达1.5公吨。鲍默文化期的铅污染（对应铅沉积量约0.4公吨）未伴随明显的铅同位素偏移，其来源极有可能为当地的生物质燃烧活动。本研究结果为探究哥伦布发现美洲前的北美原住民与当地土地及自然资源的互动利用行为所带来的环境影响提供了全新的科学认知与数据支撑。