Sediment grain-size data from the Klamath estuary, California

This data release includes grain-size measurements of sediment samples collected from the substrate surface and uppermost 10 cm of sediment deposits in the Klamath estuary, northern California. Samples were collected using a BMH-60 bed-material sampler deployed from a boat, or by hand trowel from subaerial or shallow-water (less than 0.5 m water depth) regions along the estuary margins and side channels. Sediment grain size was analyzed at the U.S. Geological Survey (USGS) laboratory in Santa Cruz, Calif. Particles coarser than 2 mm were sieved using a RO-TAP sieve shaker, and particles finer than 2 mm were analyzed with a Coulter laser particle-size analyzer (LPSA), after organic matter had been removed using a hydrogen peroxide solution. At some submerged locations where sampling was attempted, no sample was recovered. The field crew observed this occurring in places where the substrate was too coarse-grained to be collected by the bed-material sampler (cobbles), where large particles were embedded in finer (poorly sorted) matrix, and where sediment was covered by algal mats thick enough to prevent the sampler from accessing the sedimentary substrate. Locations where sampling was attempted but no sample was recovered are indicated in the 'Comments' column within the data spreadsheet. The sediment samples were collected under a Cultural Resources Management Permit issued by the Yurok Tribe, whose support the USGS acknowledges gratefully.本数据集发布内容包含从加利福尼亚州北部克拉马斯河口（Klamath estuary）的沉积物底质表面及最上层10厘米沉积层中采集的沉积物样品粒度测量数据。样品采集采用两种方式：一是从作业船上部署BMH-60型底质采样器获取样品，二是使用手铲在河口沿岸及支渠的陆上或浅水区（水深小于0.5米）开展采集。沉积物粒度分析工作在美国地质调查局（U.S. Geological Survey, USGS）加利福尼亚州圣克鲁斯实验室完成：分析前先通过过氧化氢溶液去除样品中的有机质，随后对粒径大于2毫米的颗粒使用RO-TAP筛分仪进行筛分，对粒径小于2毫米的颗粒则采用库尔特激光粒度分析仪（Coulter laser particle-size analyzer, LPSA）完成检测。部分尝试采样的水下点位未获取到有效样品，野外作业团队记录了三类未采集到样品的场景：其一为底质颗粒过于粗粒（含砾石），无法通过底质采样器完成采集；其二为大颗粒嵌于细粒（分选较差）基质中；其三为沉积物表面覆盖了厚度足以阻碍采样器接触沉积底质的藻垫。所有尝试采样但未获取样品的点位，均已在数据电子表格的「备注」列中予以标注。本沉积物样品采集工作依据尤罗克部落（Yurok Tribe）签发的文化资源管理许可开展，美国地质调查局对此深表谢意。