Collaborative Research : Analysis of the Transport and Storage of Contaminated Sediments in the Rio Pilcomayo Basin, Bolivia: A Geochemical-Geomorphologic Approach

合作研究：玻利维亚里奥皮尔科马约盆地污染沉积物的运输和储存分析：地球化学地貌学方法

• 批准号: 0207507
• 负责人: Paul Lechler
• 金额: $ 4.38万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2005-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0207507&HistoricalAwards=false
• 关键词: Collaborative; Research; Analysis; Transport; Storage

0207507Lechler The Rio Pilcomayo heads on the Cerro Rico de Potosi precious metal-polymetallic tin deposits of Bolivia. Mining of the Potosi deposits was initiated by the Spanish in 1545 and has continued without interruption to the present. Our previous studies have demonstrated that the release of mining and milling wastes to the environment during the past 450 years has resulted in extensive contamination of water and sediments of the upper Pilcomayo valley. The primary objective of this investigation is to determine if Pb isotopes can be effectively used in a large river system to quantify the decadal scale transport and storage of contaminated debris from mining operations. Inherent in the study is an analysis of the linkages between geomorphic processes and the long-term dispersal of contaminated materials.To accomplish the project objectives several tasks will be completed: (1) Pb sources within the upper reaches of Rio Pilcomayo basin will be identified and characterized in terms of their geographical distribution and Pb isotopic signatures. This step will involve the collection and analysis of ore samples from Cerro Rico, the major bedrock units that underlie the watershed, mineralized zones within tributary basins, and channel bed sediments within major tributaries; (2) the alluvial stratigraphy and geomorphology of the tributary basins will be documented and linked to the existing geomorphic-stratigraphic data on the Rio Pilcomayo to (a) refine our understanding of the timing, magnitude, and nature of historic geomorphic events that have occurred along the Rio Pilcomayo, and (b) gain insights into the timing and magnitude of sediment influx to the Rio Pilcomayo from tributaries (both of which are believed to have had an impact on the downstream movement of contaminated sediment); (3) spatial variations in the total concentration of selected metals and Pb isotopic ratios will be documented perpendicular to flow, downstream, and vertically within age-constrained alluvial deposits. Emphasis will be placed on the analysis of 1.5-2 m long cores extracted from contaminated alluvial terraces composed of vertically accreted flood deposits; and (4) sediment mixing models will be used to quantify the relative proportion of Pb in alluvial deposits that is derived from each of the delineated Pb sources.

0207507 Lechler Rio Pilcomayo位于玻利维亚的Cerro Rico de Potosi贵金属-多金属锡矿床上。 波托西矿床的开采由西班牙人于1545年开始，一直持续到现在。 我们以前的研究表明，在过去的450年里，采矿和碾磨废物向环境的释放导致了上皮科马约山谷的水和沉积物的广泛污染。 这项调查的主要目的是确定铅同位素是否可以有效地用于大型河流系统，以量化采矿作业污染碎片的十年尺度运输和储存。 为实现项目目标，将完成以下几项任务：（1）确定皮科马约河上游地区的铅源，并根据其地理分布和铅同位素特征对其进行表征。 这一步骤将涉及收集和分析来自Cerro Rico的矿石样本、流域下面的主要基岩单位、支流流域内的矿化区以及主要支流内的河床沉积物;（2）将记录支流盆地的冲积地层和地貌，并将其与Rio Pilcomayo现有的地貌地层数据联系起来，以（a）完善我们对时间的理解，规模和历史地貌事件的性质，沿着里约皮科马约河发生，以及（B）深入了解从支流流入里约皮科马约河的沉积物的时间和规模（据信这两种情况都对受污染沉积物的下游移动产生了影响）;（3）将记录所选金属总浓度和铅同位素比的空间变化，垂直于水流，下游，垂直上位于受年龄限制的冲积层内。 重点将放在分析1.5-2米长的核心提取的污染冲积阶地组成的垂直加积洪水沉积物;和（4）沉积物混合模型将被用来量化的相对比例的铅在冲积沉积物中，来自每个划定的铅源。