GEOTRACES radium isotopes interlaboratory comparison experiment

Abstract

In anticipation of the international GEOTRACES program, which will study the global marine biogeochemistry of trace elements and isotopes, we conducted a multi-lab intercomparison for radium isotopes. The intercomparison was in two parts involving the distribution of: (1) Ra) well outside the 95% confidence interval. Many outliers were suspected to be a result of poorly calibrated detectors, though other method specific factors likely played a role (e.g., detector leakage, insufficient equilibration). Most methods for radium analysis in seawater involve a MnO 2 fiber column preconcentration step; as such, we evaluated the extraction efficiency of this procedure and found that it ranged from an average of 87% to 94% for the four stations. Hence, nonquantitative radium recovery from seawater samples may also have played a role in lab-to-lab variability.

Radium Isotopes Across the Arctic Ocean Show Time Scales of Water Mass Ventilation and Increasing Shelf Inputs

“…To determine cartridge collection efficiencies, small volume samples of 226 Ra (15–25 L) were collected using a Niskin bottle mounted either on the CTD rosette (shallow casts) or above the ISPs (deep casts) and were filtered through a MnO 2 ‐coated fiber. The activities of Ra measured on the fibers, which quantitatively scavenge radium (Charette et al, ), were compared to those determined on the cartridges. For HLY1502, the collection efficiency of individual cartridges ranged from 19% to 99%, with an average of 70 ± 19% (1σ).…”

The influence of sea ice cover on air-sea gas exchange estimated with radon-222 profiles

“…Efficiencies of 97 ± 3% were reported for this method by Moore [], but the lab intercomparison reported by Charette et al . [] yielded average efficiencies of only 87–94%. Our own extraction efficiencies, determined by analyzing two columns filled with MnO 2 fibers in series, were 95–100%.…”

“…After stripping the radon gas, the samples were drained over columns filled with MnO 2 fibers at flow rates 1 L min 21 to efficiently collect the radium [Moore, 1976]. Efficiencies of 97 6 3% were reported for this method by Moore [2008], but the lab intercomparison reported by Charette et al [2012] yielded average efficiencies of only 87-94%. Our own extraction efficiencies, determined by analyzing two columns filled with MnO 2 fibers in series, were 95-100%.…”

An estimation of nutrient fluxes via submarine groundwater discharge into the Sanggou Bay—A typical multi-species culture ecosystem in China

“…SGD is now globally recognized as one of the most important and typical processes of land/ocean interactions in coastal zones (LOICZ) (Moore, 2010;Charette et al, 2012). Groundwater is generally enriched in nutrients and heavy metals through natural processes and by residential and agricultural development in near-shore areas, leading to increased inputs of nitrogen (N) and phosphorus (P) from fertilizer and wastewater (Burnett et al, 1990(Burnett et al, , 2001bCorbett et al, 1999;Moore, 1996Moore, , 1999Valiela et al, 1990).…”