Constituent Concentrations in Sediment of Selected Gravel Bars along the Big River, Southeast Missouri, 2011

Historic mining activity in the Old Lead Belt has led to substantial influx of lead and zinc mining waste into the channel of the Big River in southeastern Missouri. The primary objectives of this data collection was to determine the depth of heavy-metal contamination at five gravel bars along the Big River to verify and supplement findings by Pavlowsky and Owen (2010). A secondary objective of the study was to develop and implement methods for use in other Natural Resource Damage Assessment projects, such as the Tri-State Mining District (TSMD) project (Smith, 2016). This data was collected in cooperation with the Ozarks Environmental and Water Resources Institute, Missouri State University, and U.S. Fish and Wildlife Service (USFWS). Five gravel bars along the Big River were selected for this study. Three boreholes were drilled on each gravel bar with the exception of bar A. Due to the smaller surface area of bar A, two boreholes were drilled. Surface samples were collected in the unsaturated zone by hand methods for each boring location. A stainless steel hand scoop was used to collect sediment from 0 to 1 foot. A shovel was used to collect deeper samples in the unsaturated zone. Once a hole was excavated with a shovel, disturbed sediment was cleared away to access undisturbed sediment and a sample would be collected with a stainless steel hand scoop. A freeze method similar to that used by Lisle and Eads (1971) was used to collect the saturated samples for the project. Methods used in this study implemented a hollow sampler and was driven by means of Geoprobe direct push sampling equipment. In this study, liquid carbon dioxide was injected into the hollow sampler and sediment was frozen to the outside of the sampler. The length-wise fins on the outside of the sampler protected the frozen sample during removal by pushing coarse material away from the sampler during the retrieval process. More information about the sampler design and methods is described by Smith (2016). The frozen sample was then rinsed with deionized water while still frozen to the sampler. This removed any particles from upper layers that may have attached to the frozen sediment during retrieval. This left a solid frozen sediment sample taken from the depth at which the sample was frozen. The sediment was then scraped and rinsed into a stainless steel pan. All samples were stored in labeled double zippered plastic bags and transported to the Rolla, Missouri US Geological Survey (USGS) office. Samples were stored in the USGS repository and allowed to air dry. Once the samples were dry, the initial mass was recorded and sieved using a single #10 (2 millimeter) sieve. The two size fractions were placed in separate labeled zippered plastic bags and their masses were recorded. The less than 2 millimeter size fraction was scanned by USFWS personnel in Columbia, Missouri using a handheld x-ray fluorescence (XRF) unit to determine metal concentrations. The samples were scanned 3 times and the average concentration of the three scans for each constituent was calculated as a best representation of the constituent concentration. The individual samples were hand mixed within the bag before each scan to ensure homogeneity. Pavlowsky, R.T., Owen, M.R. and Martin, D.J., 2010, Distribution, geochemistry, and storage of mining sediment in channel and floodplain deposits of the Big River System in St. Francois, Washington, and Jefferson counties, Missouri, The Ozarks Environmental and Water Resources Institute (OEWRI), Missouri State University, 141 p., https://oewri.missouristate.edu/assets/OEWRI/Big_River_Report.pdf Smith, D.C., 2016, Occurrence, distribution, and volume of metals-contaminated sediment of selected streams draining the Tri-State Mining District, Missouri, Oklahoma, and Kansas, 2011-12: U.S. Geological Survey Scientific Investigations Report 2016-5144, 86 p., http://dx.doi.org/10.3133/sir20165144. Lisle, T.E., and Eads, R.E., 1971, Methods to measure sedimentation of spawning gravels: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station Research Note PSW-RN-411, 7 p.

密苏里州东南部大河道（Big River）沿线的历史采矿活动，已导致大量铅锌采矿废弃物汇入该河道河床。本数据采集工作的核心目标为：测定大河道沿线5处砾石滩的重金属污染深度，以验证并补充Pavlowsky与Owen（2010年）的研究发现。本研究的次要目标为，开发并推广适用于其他自然资源损害评估项目的方法，例如三州矿区（Tri-State Mining District, TSMD）项目（Smith, 2016）。本数据由奥扎克斯环境与水资源研究所、密苏里州立大学及美国鱼类及野生动物管理局（U.S. Fish and Wildlife Service, USFWS）合作采集。本次研究共选取大河道沿线的5处砾石滩，除A滩外，每处砾石滩均布设3个钻孔；因A滩地表面积较小，仅布设2个钻孔。针对每个钻孔点位，采用手工方法采集非饱和带表层样品：使用不锈钢手铲采集0至1英尺深度的沉积物；对于更深层的非饱和带样品，则先利用铁锹开挖坑体，清除扰动沉积物以暴露未扰动沉积物，再使用不锈钢手铲采集样品。饱和样品采集采用Lisle与Eads（1971年）提出的冷冻法：本研究使用空心采样器，依托Geoprobe直推式采样设备（Geoprobe direct push sampling equipment）进行驱动，向采样器内部注入液态二氧化碳，使沉积物冻结于采样器外壁；采样器外壁的纵向鳍片可在回收过程中推开粗粒物质，从而保护冻结样品。关于采样器设计与具体方法的更多细节，可参考Smith（2016）的研究成果。将附着有冻结沉积物的采样器用去离子水冲洗，以去除回收过程中附着于冻结沉积物表层的颗粒，从而获得对应采样深度的固态冻结沉积物样品；随后将沉积物刮取并冲洗至不锈钢托盘内。所有样品均装入贴有标签的双拉链塑料袋中，运送至密苏里州罗拉市的美国地质调查局（U.S. Geological Survey, USGS）办公室，储存在USGS仓库内进行风干。样品风干后，记录初始质量，再通过10号（2毫米）筛进行筛分；将两个粒级的样品分别装入贴有标签的拉链塑料袋中，并记录各自质量。粒径小于2毫米的粒级样品，由USFWS人员于密苏里州哥伦比亚市使用手持X射线荧光（X-ray fluorescence, XRF）仪进行扫描，以测定金属浓度。每份样品均扫描3次，以三次扫描的平均浓度作为该组分浓度的最优表征值；每次扫描前均需手工混匀袋内样品，以保证均质性。Pavlowsky, R.T., Owen, M.R. 及 Martin, D.J., 2010年，密苏里州圣弗朗索瓦、华盛顿与杰斐逊县大河道系统河道及漫滩沉积物中采矿沉积物的分布、地球化学特征与储存量，奥扎克斯环境与水资源研究所（OEWRI），密苏里州立大学，141页，https://oewri.missouristate.edu/assets/OEWRI/Big_River_Report.pdf；Smith, D.C., 2016年，2011-2012年密苏里州、俄克拉荷马州与堪萨斯州三州矿区流域溪流中重金属污染沉积物的赋存、分布与体积：美国地质调查局科学调查报告2016-5144，86页，http://dx.doi.org/10.3133/sir20165144；Lisle, T.E. 与 Eads, R.E., 1971年，产卵砾石沉积物沉积量测定方法：美国农业部森林服务局太平洋西南森林与牧场实验站研究笔记PSW-RN-411，7页。