Cleaning of lake sediment samples for diatom oxygen isotope analysis

Biogeochemical processes controlling oxygen and carbon isotopes of diatom silica in Late Glacial to Holocene lacustrine rhythmites

“…2). The samples were treated following the method proposed by Morley et al (2004) with some modifications (Hernández et al, 2008;Hurrell, 2010). This method involved chemical attack, sieving, settling and laminar flow separation.…”

Isotope offsets in marine diatom δ18O over the last 200 ka

“…carbonates before being further cleaned of non-diatom contaminants using sodium polytungstate (SPT), a heavy liquid, at a series of specific gravities from 2.10-2.25 g/ml (Morley et al, 2004). The use of SPT was particularly important for the smaller 38-75 μm size fraction where the relative amount of contaminants was significantly higher.…”

“…Further SEM analyses were undertaken on selected samples to ensure diatom purity. For the light microscopy work, contamination was assessed following the the semi-quantitative approach of Morley et al, (2004) but using 30 rather than 10 quadrants on a 100 μm × 100 μm grid graticule. Quadrants were selected in a semi-random way such that areas representative of the whole coverslip were sampled including the edge where more contamination may be present.…”

Reconstructing hydrological variability in Lake Baikal during MIS 11: an application of oxygen isotope analysis of diatom silica

“…To do this, a 184 small amount of cleaned sediment was prepared for microscopy prior to final drying as 185 above, so that the degree of silt remaining in each sample could be assessed at x1000 186 magnification using a 10 x 10 grid graticule (Morley et al 2004). For each sample, 187 diatom and contaminant content were estimated semi-quantitatively as a proportion of the 188 non-empty graticule grid squares counted.…”