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Purpose <p>Beryllium-7 has been widely applied as sediment tracer in river basins, however, factors influencing its geochemistry in this context have rarely been addressed. We investigated sediment-water interactions controlling the distribution of <sup>7</sup>Be in channel sediments for improved storage time and particulate contaminant dynamic assessments in a catchment affected by legacy and contemporary mining pollution.</p> Methods <p>The investigation was undertaken in the River Fal, UK, to assess sediment storage times and particulate contaminant dynamics. Samples were collected and analysed for <sup>7</sup>Be, <sup>137</sup>Cs, <sup>210</sup>Pb and <sup>238</sup>U by gamma spectrometry, aqua regia extractable P, As, Fe, Cu, Pb, Sn and Zn by inductively coupled plasma (ICP) spectrometry and Total Organic Carbon (TOC) by CHN analyser. Particle size distribution (PSD) and the 1&#xa0;mol L<sup>− 1</sup> HNO<sub>3</sub> extractable Fe and Mn fractions were analysed by laser diffraction and ICP, respectively, to assess relationships with the radionuclide activities. Dissolved and the 1&#xa0;mol L<sup>− 1</sup> HCl extractable <sup>9</sup>Be was quantified to determine its distribution coefficients (K<sub>d</sub>).</p> Results <p>Beryllium-7 was significantly correlated with the specific surface area (SSA), TOC and the Fe and Mn extractable fractions. A strong inverse correlation between the <sup>9</sup>Be K<sub>d</sub> and suspended sediment concentration (SSC) demonstrated the particle concentration effect. Suspended sediments (SS) showed higher SSA than the channel bar sediments (CBS). Storage times and the proportion of recently deposited sediments (% RDS) were estimated using different methods for addressing particle size effects, which were not statistically different.</p> Conclusions <p>Occurrence of particulate contaminants was related to two dominant sources and processes: (1) in the upstream site, co-precipitation with Fe-oxides and Organic Matter (OM) enrichment; and (2) in the lower site, reworking from historic polymetallic mining during high flow events with wider relevance to legacy pollution challenges in mine-impacted rivers.</p>

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Controls on the distribution of 7Be for an improved understanding of sediment and associated contaminant storage

  • 期刊论文

  • 发表日期：

    2026年3月2日

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  • Enrique G. Muñoz-Arcos,
  • Caroline C. Clason,
  • Geoffrey E. Millward,
  • Claudio M. Bravo-Linares,
  • Robert Clough,
  • William H. Blake

摘要

Purpose

Beryllium-7 has been widely applied as sediment tracer in river basins, however, factors influencing its geochemistry in this context have rarely been addressed. We investigated sediment-water interactions controlling the distribution of 7Be in channel sediments for improved storage time and particulate contaminant dynamic assessments in a catchment affected by legacy and contemporary mining pollution.

Methods

The investigation was undertaken in the River Fal, UK, to assess sediment storage times and particulate contaminant dynamics. Samples were collected and analysed for 7Be, 137Cs, 210Pb and 238U by gamma spectrometry, aqua regia extractable P, As, Fe, Cu, Pb, Sn and Zn by inductively coupled plasma (ICP) spectrometry and Total Organic Carbon (TOC) by CHN analyser. Particle size distribution (PSD) and the 1 mol L− 1 HNO3 extractable Fe and Mn fractions were analysed by laser diffraction and ICP, respectively, to assess relationships with the radionuclide activities. Dissolved and the 1 mol L− 1 HCl extractable 9Be was quantified to determine its distribution coefficients (Kd).

Results

Beryllium-7 was significantly correlated with the specific surface area (SSA), TOC and the Fe and Mn extractable fractions. A strong inverse correlation between the 9Be Kd and suspended sediment concentration (SSC) demonstrated the particle concentration effect. Suspended sediments (SS) showed higher SSA than the channel bar sediments (CBS). Storage times and the proportion of recently deposited sediments (% RDS) were estimated using different methods for addressing particle size effects, which were not statistically different.

Conclusions

Occurrence of particulate contaminants was related to two dominant sources and processes: (1) in the upstream site, co-precipitation with Fe-oxides and Organic Matter (OM) enrichment; and (2) in the lower site, reworking from historic polymetallic mining during high flow events with wider relevance to legacy pollution challenges in mine-impacted rivers.