Measurement of 7Be in soils and sediments by gamma spectroscopy

Landis, Joshua D.; Renshaw, Carl E.; Kaste, James M.

doi:10.1016/j.chemgeo.2011.10.007

Cited by 32 publications

(25 citation statements)

References 58 publications

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“…Each sample count rate was corrected for decay, self‐attenuation, detector efficiency, and interference with 228 Ac (for 7 Be) following the methods described by Landis et al . (). Precipitation samples were counted in 1 L Marinelli beakers.…”

Section: Methodsmentioning

confidence: 97%

“…Each sample taken from the margin or bed was sieved to 2 mm, packed and sealed into a plastic container and placed in the detector for 1 day. Each sample count rate was corrected for decay, selfattenuation, detector efficiency, and interference with 228 Ac (for 7 Be) following the methods described by Landis et al (2012b). Precipitation samples were counted in 1 L Marinelli beakers.…”

Section: Sample Filtrationmentioning

confidence: 99%

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Joint isotopic mass balance: a novel approach to quantifying channel bed to channel margins sediment transfer during storm events

Underwood

Renshaw

Dade

et al. 2015

Earth Surf Processes Landf

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The important role of floodplains and the broader riparian zone in providing temporary storage for a large fraction of the annual sediment load of rivers is well established, but this understanding is largely based on observations of the long-term average behavior of the catchment. Here we combine measurements of the fallout radionuclides 7 Be and 210 Pb and the stable isotopes of hydrogen in water to quantify fine sediment mobilization and storage in a stream and its channel margins during individual intermediate-sized storm events with recurrence intervals of a few months or less. We demonstrate this method using five storm events in a small (~15 km 2 ), undeveloped, gravel-bedded tributary of the Connecticut River (USA). We estimate that in each storm, the mass of sediment deposited onto the margins accounts for almost 90% of the sediment mobilized from the bed, with the remainder of the mobilized bed sediment transported downstream as suspended load. The result that the bed is a net source of sediment to the stream and the margins a net sink is robust, but estimates of the mass of material eroded from the bed and deposited on the margins are less certain. The source of sediment to the bed remains unclear as, consistent with earlier studies, we observe only limited deposition of sediment to the bed during the storm events. The suspended sediment is organic-rich and thus its source may be associated with in-channel organic decay between storm events. Understanding the coupled interactions between discharge magnitude and frequency and sediment resupply at the event time scale has important implications for stream restoration efforts seeking to connect the channel and the broader riparian zone, and for the development of accurate sediment budgets and predictions of sediment flux from a watershed.

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Section: Methodsmentioning

confidence: 97%

Section: Sample Filtrationmentioning

confidence: 99%

Joint isotopic mass balance: a novel approach to quantifying channel bed to channel margins sediment transfer during storm events

Underwood

Renshaw

Dade

et al. 2015

Earth Surf Processes Landf

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“…We must also conclude that the postdepositional redistribution of radioiodine, as observed and reported here, manifests the natural cycling of stable 127 iodine in a temperate, terrestrial ecosystem. (55). For this study large samples (110 cm 3 for solids, 1 L for waters) were measured in bulk and field-wet to avoid losses of 131 I resulting from handling or interactions with equipment materials, or by decay during prolonged processing.…”

Section: Resultsmentioning

confidence: 99%

Surficial redistribution of fallout¹³¹iodine in a small temperate catchment

Landis

Hamm²,

Renshaw³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Isotopes of iodine play significant environmental roles, including a limiting micronutrient ( 127 I), an acute radiotoxin ( 131 I), and a geochemical tracer ( 129 I). But the cycling of iodine through terrestrial ecosystems is poorly understood, due to its complex environmental chemistry and low natural abundance. To better understand iodine transport and fate in a terrestrial ecosystem, we traced fallout 131 iodine throughout a small temperate catchment following contamination by the 11 March 2011 failure of the Fukushima Daiichi nuclear power facility. We find that radioiodine fallout is actively and efficiently scavenged by the soil system, where it is continuously focused to surface soils over a period of weeks following deposition. Mobilization of historic (pre-Fukushima) 137 cesium observed concurrently in these soils suggests that the focusing of iodine to surface soils may be biologically mediated. Atmospherically deposited iodine is subsequently redistributed from the soil system via fluvial processes in a manner analogous to that of the particle-reactive tracer 7 beryllium, a consequence of the radionuclides’ shared sorption affinity for fine, particulate organic matter. These processes of surficial redistribution create iodine hotspots in the terrestrial environment where fine, particulate organic matter accumulates, and in this manner regulate the delivery of iodine nutrients and toxins alike from small catchments to larger river systems, lakes and estuaries.

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“…Using a technique that is similar to the one thoroughly described in Landis et al . (), we measured a Th ore in our standard counting geometry to define a relationship between the 228 Ac emission at 478.3 keV and other 228 Ac lines (463 keV, 911 keV) that are easily quantified in samples. This relationship was used to project and subtract the 228 Ac interference from the net photopeak area at 477–478 keV in the unknown sample spectrums.…”

Section: Methodsmentioning

confidence: 99%

“…Larsen and Cutshall (1981) found that for a 250 g sediment sample, differences in attenuation of the 7 Be gamma between a calibrating solution and sediment matrix were negligible, so we make no attenuation correction for our liquid-derived detection efficiency. We summed the counts in the five-channel 7 Be region of interest spanning 476.5-478.5 keV and used a best line-of-fit model background based on neighbouring channels which avoided the documented 480 keV decay emission of 214 Pb (Morel et al, 2004;Landis et al, 2012). Masses of 125-175 g (<2 mm) were typically counted for 24-48 h. Other U-series radionuclide ( 210 Pb, 226 Ra) and Th-series ( 228 Ac) activities were determined using standard techniques (Cutshall et al, 1983;Murray et al, 1987).…”

Section: Methodsmentioning

confidence: 99%

Seasonal controls on meteoric⁷Be in coarse-grained river channels

et al. 2013

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Cosmogenic 7Be is a natural tracer of short‐term hydrological processes, but its distribution in upland fluvial environments over different temporal and spatial scales has not been well described. We measured 7Be in 450 sediment samples collected from perennial channels draining the middle of the Connecticut River Basin, an environment that is predominantly well‐sorted sand. By sampling tributaries that have natural and managed fluctuations in discharge, we find that the 7Be activity in thalweg sediments is not necessarily limited by the supply of new or fine‐grained sediment, but is controlled seasonally by atmospheric flux variations and the magnitude and frequency of bed mobilizing events. In late winter, 7Be concentrations in transitional bedload are lowest, typically 1 to 3 Bq kg−1 as 7Be is lost from watersheds via radioactive decay in the snowpack. In mid‐summer, however, 7Be concentrations are at least twice as high because of increased convective storm activity which delivers high 7Be fluxes directly to the fluvial system. A mixed layer of sediment at least 8 cm thick is maintained for months in channels during persistent low rainfall and flow conditions, indicating that stationary sediments can be recharged with 7Be. However, bed mobilizing rain on snowmelt events in late Spring can ‘reset’ 7Be amounts and concentrations in the channel as previously buried ‘old’ sediment with low 7Be is mixed into the thalweg. We conclude that given proper temporal and spatial sampling, 7Be is a valuable tracer of seasonal‐timescale mass transport and exchange in coarse‐grained fluvial systems. Copyright © 2013 John Wiley & Sons, Ltd.

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Measurement of 7Be in soils and sediments by gamma spectroscopy

Cited by 32 publications

References 58 publications

Joint isotopic mass balance: a novel approach to quantifying channel bed to channel margins sediment transfer during storm events

Joint isotopic mass balance: a novel approach to quantifying channel bed to channel margins sediment transfer during storm events

Surficial redistribution of fallout¹³¹iodine in a small temperate catchment

Seasonal controls on meteoric⁷Be in coarse-grained river channels

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Measurement of 7Be in soils and sediments by gamma spectroscopy

Cited by 32 publications

References 58 publications

Joint isotopic mass balance: a novel approach to quantifying channel bed to channel margins sediment transfer during storm events

Joint isotopic mass balance: a novel approach to quantifying channel bed to channel margins sediment transfer during storm events

Surficial redistribution of fallout131iodine in a small temperate catchment

Seasonal controls on meteoric7Be in coarse-grained river channels

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Product

Resources

About

Surficial redistribution of fallout¹³¹iodine in a small temperate catchment

Seasonal controls on meteoric⁷Be in coarse-grained river channels