High resolution aerosol concentration data from the Greenland NorthGRIP and NEEM deep ice cores

Records of chemical impurities from ice cores enable us to reconstruct the past deposition of aerosols onto the polar ice sheets and alpine glaciers. Through that, they allow us to gain insight into changes of the source, transport and deposition processes that ultimately determine the deposition flux at the coreing location. However, the low concentrations of the aerosol species in the ice and the resulting high risk of contamination poses a formidable analytical challenge, especially if long, continuous and highly resolved records are needed. Continuous Flow Analysis, CFA, the continuous melting, decontamination and analysis of ice-core samples has mostly overcome this issue and has quickly become the de-facto standard to obtain high-resolution aerosol records from ice cores after its inception at the University of Bern in the mid 90s. Here we present continuous records of calcium (Ca2+), sodium (Na+), ammonium (NH4+), nitrate (NO3−1) and electrolytic conductivity at 1 mm depth resolution from the NGRIP (North Greenland Ice Core Project) and NEEM (North Greenland Eemian Ice Drilling) ice cores produced by the Bern Continuous Flow Analysis group in the years 2000 to 2011. Both of the records have previously been used in a number of studies but have never been published in the full 1 mm resolution. Alongside the 1 mm datasets we provide decadal averages, a detailed description of the methods, relevant references, an assessment of the quality of the data and its usable resolution. Along the way we will also give some historical context on the development of the Bern CFA system.

Continuous flow analysis methods for sodium, magnesium and calcium detection in the Skytrain ice core

Dissolved and particulate sodium, magnesium and calcium are analyzed in ice cores to determine past changes in sea ice extent, terrestrial dust variability and atmospheric aerosol transport efficiency. They are also used to date ice cores if annual layers are visible. Multiple methods have been developed to analyze these important compounds in ice cores. Continuous flow analysis (CFA) is implemented with instruments that sample the meltstream continuously. In this study, CFA with ICP-MS (inductively coupled-plasma mass spectrometry) and fast ion chromatography (FIC) methods are compared for analysis of sodium and magnesium. ICP-MS, FIC and fluorescence methods are compared for analysis of calcium. Respective analysis of a 10 m section of the Antarctic WACSWAIN Skytrain Ice Rise ice core shows that all of the methods result in similar levels of the compounds. The ICP-MS method is the most suitable for analysis of the Skytrain ice core due to its superior precision (relative standard deviation: 1.6% for Na, 1.3% for Mg and 1.2% for Ca) and sampling frequency compared to the FIC method. The fluorescence detection method may be preferred for calcium analysis due to its higher depth resolution (1.4 cm) relative to the ICP-MS and FIC methods (~4 cm).

Microstructure, Micro-inclusions and Mineralogy along the EGRIP ice core – Part 2: Implications for paleo-mineralogy

Impurities in polar ice do not only allow the reconstruction of past atmospheric aerosol concentration, but also in- fluence the physical properties of the ice. However, the mineralogy and location of impurities in ice and the involved processes are poorly understood. We use Continuous Flow Analysis to derive the dust particle concentration and optical microscopy and Cryo-Raman spectroscopy to systematically locate and analyse the mineralogy of micro-inclusions in situ inside eleven solid ice samples from the upper 1340 m of the East Greenland Ice Core Project ice core. Micro-inclusions are more variable in min- eralogy than previously observed and are mainly composed of mineral dust (quartz, mica and feldspar) and sulphates (mainly gypsum). Inclusions of the same composition tend to cluster, but clustering frequency and mineralogy changes considerably with depth. A variety of sulphates dominate the upper 900 m while gypsum is the only sulphate in deeper samples, which however contain more mineral dust, nitrates and dolomite. The analysed part of the core can thus be divided into two depth regimes of different mineralogy, and to a lesser degree of spatial distribution, which could originate from different chemical reactions in the ice or large-scale changes of ice cover in NE-Greenland during the Mid-Holocene. The complexity of impurity mineralogy on the metre- and centimetre-scale in polar ice is still underestimated and new methodological approaches are necessary to establish a comprehensive understanding of the role of impurities.

APPLICATION OF ION-EXCHANGE MEMBRANE SYSTEMS IN CONTINUOUS FLOW ANALYSIS

The use of ion-selective membrane systems for measuring the quantitative composition of ions of some trivalent metals in process water media and wastewater under continuous flow systems is con-sidered and experimentally investigated.

Continuous flow analysis of the Mount Brown South ice core

<p>The Mount Brown South (MBS) ice core is an approximately 300-meter-long ice core, drilled in 2016-2017 to the south of Mount Brown, Wilhelm II Land, East Antarctica. This location in East Antarctica was chosen as it produces an ice core with well-preserved sub-annual records of both chemistry and isotope concentrations, spanning back over 1000 years. MBS is particularly well suited to represent climate variations of the Indian Ocean sector of Antarctica, and to provide information about regional volcanism in the Southern Indian Ocean region.</p><p>A section of ice spanning the length of the MBS core was melted as part of the autumn 2019 continuous flow analysis (CFA) campaign at the Physics of Ice, Climate, and Earth (PICE) group at the University of Copenhagen. During this campaign, measurements were conducted for chemistry and impurities contained in the ice, in addition to water isotopes. The data measured in Copenhagen include measurements of H<sub>2</sub>O<sub>2,</sub> pH, electrolytic conductivity, and NH<sub>4</sub><sup>+</sup>, Ca<sup>2+</sup>, and Na<sup>+</sup> ions, in addition to insoluble particulate concentrations and size distribution measured using an Abakus laser particle counter.</p><p>Here, we present an overview of the CFA chemistry and impurity data, as well as preliminary investigations into the size distribution of insoluble particles and the presence of volcanic material within the ice. These initial chemistry and particulate size distribution data sets are useful in order to identify sections of the MBS core to subject to further analysis to increase our understanding of volcanic activity in the Southern Indian Ocean region.</p>

Continuous-Flow Analysis of δ17O, δ18O, and δD of H2O on an Ice Core from the South Pole

The δD and δ18O values of water are key measurements in polar ice-core research, owing to their strong and well-understood relationship with local temperature. Deuterium excess, d, the deviation from the average linear relationship between δD and δ18O, is also commonly used to provide information about the oceanic moisture sources where polar precipitation originates. Measurements of δ17O and “17O excess” (Δ17O) are also of interest because of their potential to provide information complementary to d. Such measurements are challenging because of the greater precision required, particularly for Δ17O. Here, high-precision measurements are reported for δ17O, δ18O, and δD on a new ice core from the South Pole, using a continuous-flow measurement system coupled to two cavity ring-down laser spectroscopy instruments. Replicate measurements show that at 0.5 cm resolution, external precision is ∼0.2‰ for δ17O and δ18O, and ∼1‰ for δD. For Δ17O, achieving external precision of <0.01‰ requires depth averages of ∼50 cm. The resulting ∼54,000-year record of the complete oxygen and hydrogen isotope ratios from the South Pole ice core is discussed. The time series of Δ17O variations from the South Pole shows significant millennial-scale variability, and is correlated with the logarithmic formulation of deuterium excess (dln), but not the traditional linear formulation (d).