A Simplified Drying Procedure for Analysing Hg Concentrations

Abstract

Mercury (Hg) in peatlands remains a problem of global interest. To mitigate the risks of this neurotoxin, accurate assessments of Hg in peat are needed. Treatment of peat that will be analysed for Hg is, however, not straightforward due to the volatile nature of Hg. The drying process is of particular concern since Hg evasion increases with the temperature. Samples are, therefore, often freeze-dried to limit Hg loss during the drying processes. A problem with freeze-drying is that cost and equipment resources can limit the number of samples analysed in large projects. To avoid this bottleneck, we tested if drying in a 60 °C-degree oven could be an acceptable alternative to freeze-drying. We both freeze-dried and oven-dried (60 °C) 203 replicate pairs of peat samples, and then examined the differences in total Hg concentration. The Hg concentration differed significantly between the two drying methods with a median Hg deficit in oven-dried samples of 4.2%. Whether a 4.2% deficit of Hg depends on one’s purpose. The lower median Hg concentration in oven-dried samples has to be weighed against the upside efficiently drying large sets of peat samples. By freeze-drying a subset of the samples, we fitted a function to correct for Hg loss during oven-drying ($$y=0.96x+0.08)$$ y = 0.96 x + 0.08 ) . By applying this correction, the freeze-drying bottleneck could oven-dry large-scale inventories of total Hg in peatlands with results equivalent to freeze-drying, but only have to freeze-dry a subset.

Ecological Risk Assessment of Heavy Metal (Pb, Cu) Contamination in Water, Sediment, and Polychaeta (<i>Neoleanira Tetragona</i>) from Coastal Areas Affected by Aquaculture, Urban Rivers, and Ports in South Sumatra

“…The water sample preparation stage was carried out by filtering using 0.45 µm Whatman paper [Agasti, 2021]. Meanwhile, sediment preparation was done by cleaning it from foreign objects, drying it in an electric oven at 60°C for 30 minutes, grinding it into powder until it had fine particles, and storing it in a polyethylene bottle [Smeds et al, 2022]. Next, the polychaeta samples were cleaned and crushed using a pestle and mortar [Rapi et al, 2020].…”

Environmental risk assessment of Pb, Cu, Zn, and Cd concentrations accumulated in selected mangrove roots and surrounding their sediment

“…The digests were transferred to 50-mL vials with ultra-distilled water and stored in polyethylene containers at room temperature until further measurement. The sediment sample was prepared by cleaning it from foreign objects, drying it in an electric oven at 60°C for 30 minutes, grinding it into powder until it had fine particles, and storing it in a polyethylene bottle (Smeds et al 2022). Next, the root samples were cleaned and crushed using a pestle mortar (Rapi et al 2020).…”

Global Patterns of Metal and Other Element Enrichment in Bog and Fen Peatlands

“…Samples were analyzed in duplicates and total Hg measurements were provided in mg kg − 1 units. A small amount of Hg may also have been lost during our drying procedure as Smeds et al (2022) reported that the median loss of Hg in samples dried at 60 o C was 4.1% compared with freeze dried samples. However, recovery in our analysis was within the same range of other elements measured in this study (> 93%), so any differences in Hg enrichment most likely re ects the unique behavior of Hg in the environment rather than an artifact caused by our analysis.…”