Investigation of self-attenuation of Pb (46 keV) gamma ray in sediment, certified reference material and high-density minerals: Implication to precise measurement of Pb.

High resolution gamma spectrometry is one of the most widely used techniques in the measurements of environmental level Pb in sediment from coastal and freshwater environments and such measurements are needed to establish Pb chronology for the past 100-150 years. Precise measurement of Pb in sediment and soil requires appropriate self-absorption correction for its low-energy (46.5 keV) gamma radiation due to differences in the matrix between the sample and standard used to calibrate the instrument.

Quantification of Po-210 and Pb-210 as tracer of sediment resuspension rate in a shallow riverine system: Case study from southeast Michigan, USA.

Polonium-210 and Pb-210 were measured in surficial benthic sediments and particulate matter collected in sediment traps deployed at five different locations in the Clinton River, a dynamic system, in Lake St. Clair in Southeast Michigan to quantify the sediment resuspension rates and determine the particle residence time. The mean Po/Pb activity ratio of suspended trap and surficial bottom sediments were 0.

Contributions of artifactual materials to the toxicity of anthropogenic soils and street dusts in a highly urbanized terrain.

A study was undertaken to test the hypothesis that the presence of fly ash and other artifactual materials (AMs) significantly increases the toxicity of urban soil and street dust. AMs were distinguished as artifacts (artificial particles > 2 mm in size), and particulate artifacts (≤2 mm in size); street dust was the <63 μm fraction of street sediments. Reference artifacts, street dusts, and topsoils representing different land use types in Detroit, Michigan were analyzed for miscellaneous radionuclides, trace elements, magnetic susceptibility (MS), and acetic acid-extractable (leachable) Pb.

Changes in the mercury isotopic composition of sediments from a remote alpine lake in Wyoming, USA.

Mercury (Hg) deposition from the atmosphere has increased dramatically since 1850 and Hg isotope records in lake sediments can be used to identify changes in the sources and cycling of Hg. We collected a sediment core from a remote lake (Lost Lake, Wyoming, USA) and measured vertical variation of Hg concentration and isotopic composition as well as Pb and Cs activities to establish a chronology. We also analyzed vegetation and soil samples from the watershed which has a small ratio of watershed area to lake surface area (2.

Comparison of the scavenging intensity, remineralization and residence time of Po and Pb at key zones (biotic, sediment-water and hydrothermal) along the East Pacific GEOTRACES transect.

The contrasting geochemical behavior of two long-lived progeny of Rn (daughter product of Ra), Po and Pb, provide valuable insights on the extent of recycling of biogenic particulate matter and their preferential removal from the water column. We collected and analyzed 135 water samples from six vertical profiles for Po and Pb as well as a suite of aerosol samples for Pb along the US GEOTRACES East Pacific Zonal Transect (GP16). Calculated atmospheric depositional flux of Pb from the measured Pb activity in aerosols exhibits an overall decrease from east to west along the cruise track.

Po and Pb disequilibrium at the PN section in the East China Sea.

Lead-210 and Po have been widely used as tracers for quantifying particulate scavenging in the upper layer of the oceanic water column. In this study, we investigated the Po/Pb disequilibrium in the water column of the PN section in the East China Sea (ECS) during autumn 2013. In most of the water column, a deficiency of Po was observed with respect to its parent nuclide Pb (i.

Historical Associations of Molecular Measurements of Escherichia coli and Enterococci to Anthropogenic Activities and Climate Variables in Freshwater Sediment Cores.

This study investigated the long-term associations of anthropogenic (sedimentary P, C, and N concentrations, and human population in the watershed), and climatic variables (air temperature, and river discharge) with Escherichia coli uidA and enterococci 23S rRNA concentrations in sediment cores from Anchor Bay (AB) in Lake St. Clair, and near the mouth of the Clinton River (CR), Michigan. Calendar year was estimated from vertical abundances of (137)Cs.

Problems with the dating of sediment core using excess (210)Pb in a freshwater system impacted by large scale watershed changes.

Pb-210 dating of freshwater and coastal sediments have been extensively conducted over the past 40 years for historical pollution reconstruction studies, sediment focusing, sediment accumulation and mixing rate determination. In areas where there is large scale disturbance of sediments and the watershed, the vertical profiles of excess (210)Pb ((210)Pbxs) could provide erroneous or less reliable information on sediment accumulation rates. We analyzed one sediment core from Hendrix Lake in southwestern Arkansas for excess (210)Pb and (137)Cs.

Evaluation of plating conditions for the recovery of ²¹⁰Po on a Ag planchet.

The polonium-210 in the sea and its radiological consequences have been widely studied. Current processes for (210)Po recovery from seawater vary significantly. We compared selected processes to determine optimal conditions for recovery in modestly equipped laboratories.

Anthropogenic and natural radionuclides in caribou and muskoxen in the western Alaskan Arctic and marine fish in the Aleutian Islands in the first half of 2000s.

A number of caribou and muskoxen samples from the western Alaskan Arctic and fish samples from the Aleutian Islands were collected between 1998 and 2006 and analyzed for anthropogenic ((90)Sr and (137)Cs) and natural radionculides ((40)K, (210)Pb and (226)Ra), as part of the radiological assessment for the regional subsistence hunting communities in the first half of 2000s. We examined the relationship between the activities of these nuclides with the size of the fish. In caribou samples, concentration of (90)Sr in muscle was below the detection limit of 0.