Real time degradation studies on polyurethane household sponges in Danish weather and marine environments.

Polyurethane (PUR) ether sponges represent a widely-used cleaning tool with a short service lifetime resulting in the production of high quantities of waste. However, the fate of PUR in natural environments is poorly understood. In this study, sponges were exposed to the natural environments of Danish weather and seawater for two years. Physiochemical changes were monitored using visual, microscopic, spectroscopic and chromatographic techniques. Results from Attenuated Total Reflection-Fourier Transform Infrared spectroscopy and change in mass indicated that photo-oxidation was the primary degradation pathway of polyurethane ether- based sponges with a specific surface degradation rate of 12,500 µm year-1 in Danish weather. Significantly, analysis by gas chromatography-mass spectrometry showed the release to the environment of toxic substance TDI as a product of photo-oxidation. Although PUR degraded more slowly in seawater than in weather, flame retardant TMCP leached from sponges to water, indicating potential health risks of PUR waste to aquatic life.

A 5700 year-old human genome and oral microbiome from chewed birch pitch.

The rise of ancient genomics has revolutionised our understanding of human prehistory but this work depends on the availability of suitable samples. Here we present a complete ancient human genome and oral microbiome sequenced from a 5700 year-old piece of chewed birch pitch from Denmark. We sequence the human genome to an average depth of 2.3× and find that the individual who chewed the pitch was female and that she was genetically more closely related to western hunter-gatherers from mainland Europe than hunter-gatherers from central Scandinavia. We also find that she likely had dark skin, dark brown hair and blue eyes. In addition, we identify DNA fragments from several bacterial and viral taxa, including Epstein-Barr virus, as well as animal and plant DNA, which may have derived from a recent meal. The results highlight the potential of chewed birch pitch as a source of ancient DNA.

Oxygen consumption by conserved archaeological wood.

Rates of oxygen consumption have been measured over extended time periods for 29 whole samples of conserved, archaeological wood and four samples of fresh, unconserved wood, at 50% relative humidity and room temperature. Samples from the Swedish Warship Vasa and the Danish Skuldelev Viking ships are included. Most rates were close to 1 µg O2 (g wood)(-1) day(-1) and the process persisted for several years at least. Consumption of oxygen is related to change in chemical composition, which is, in turn, related to degradation. It is thus demonstrated that despite conservation, waterlogged archaeological wood continues to degrade in a museum climate.