Cascading tipping points of Antarctica and the Southern Ocean.

Antarctica and the Southern Ocean are key elements in the physical and biological Earth system. Human-induced climate change, and other human activities in the region, are leading to several potential interacting tipping points with major and irreversible consequences. Here, we examine eight potential physical, biological, chemical, and social Antarctic tipping points.

Data collation for climate-cooling gas dimethylsulfide in Antarctic snow, sea ice and underlying seawater.

Dimethylsulfide (DMS) is a climatically active volatile sulfur compound found in Earth's oceans and atmosphere that plays an important role in cloud formation. DMS originates from its precursor dimethylsulfoniopropionate (DMSP), which is produced by several classes of phytoplankton. Concentrations of DMS and DMSP in Antarctic sea ice, snow and underlying seawater are not well documented and there is currently no dataset available to find the existing data.

Microplastic contamination in east Antarctic sea ice.

The durability of plastics in the marine environment has led to concerns regarding the pervasiveness of this debris in remote polar habitats. Microplastic (MP) enrichment in East Antarctic sea ice was measured in one ice core sampled from coastal land-fast sea ice. The core was processed and filtered material was analyzed using micro Fourier-Transform Infrared (μFTIR) spectroscopy.

Critical evaluation of a seaFAST system for the analysis of trace metals in marine samples.

A seawater preconcentration system (seaFAST) with offline sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS) detection was critically evaluated for ultra-low trace elemental analysis of Southern Ocean samples over a four-year period (2015-2018). The commercially available system employs two Nobias PA1 resin columns for buffer cleaning and sample preconcentration, allowing salt matrix removal with simultaneous extraction of a range of trace elements. With a primary focus on method simplicity and practicality, a range of experimental parameters relevant to oceanographic analysis were considered, including reduction of blank levels (over weeks and years), instrument conditioning, extraction efficiencies over different pH ranges (5.

The biogeochemical role of baleen whales and krill in Southern Ocean nutrient cycling.

The availability of micronutrients is a key factor that affects primary productivity in High Nutrient Low Chlorophyll (HNLC) regions of the Southern Ocean. Nutrient supply is governed by a range of physical, chemical and biological processes, and there are significant feedbacks within the ecosystem. It has been suggested that baleen whales form a crucial part of biogeochemical cycling processes through the consumption of nutrient-rich krill and subsequent defecation, but data on their contribution are scarce.

Modern sampling and analytical methods for the determination of trace elements in marine particulate material using magnetic sector inductively coupled plasma-mass spectrometry.

Trace elements often limit phytoplankton growth in the ocean, and the quantification of particulate forms is essential to fully understand their biogeochemical cycling. There is presently a lack of reliable measurements on the trace elemental content of marine particles, in part due to the inadequacies of the sampling and analytical methods employed. Here we report on the development of a series of state-of-the-art trace metal clean methods to collect and process oceanic particulate material in open-ocean and sea ice environments, including sampling, size-fractionated filtration, particle digestions and analysis by magnetic sector inductively coupled plasma-mass spectrometry (ICP-MS).

High-accuracy determination of iron in seawater by isotope dilution multiple collector inductively coupled plasma mass spectrometry (ID-MC-ICP-MS) using nitrilotriacetic acid chelating resin for pre-concentration and matrix separation.

In the present paper we describe a robust and simple method to measure dissolved iron (DFe) concentrations in seawater down to <0.1 nmol L(-1) level, by isotope dilution multiple collector inductively coupled plasma mass spectrometry (ID-MC-ICP-MS) using a (54)Fe spike and measuring the (57)Fe/(54)Fe ratio. The method provides for a pre-concentration step (100:1) by micro-columns filled with the resin NTA Superflow of 50 mL seawater samples acidified to pH 1.

Precise measurement of Fe isotopes in marine samples by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS).

A novel analytical technique for isotopic analysis of dissolved and particulate iron (Fe) from various marine environments is presented in this paper. It combines coprecipitation of dissolved Fe (DFe) samples with Mg(OH)(2), and acid digestion of particulate Fe (PFe) samples with double pass chromatographic separation. Isotopic data were obtained using a Nu Plasma MC-ICP-MS in dry plasma mode, applying a combination of standard-sample bracketing and external normalization by Cu doping.