Persistence of plastic debris and its colonization by bacterial communities after two decades on the abyssal seafloor.

The fate of plastic debris entering the oceans is largely unconstrained. Currently, intensified research is devoted to the abiotic and microbial degradation of plastic floating near the ocean surface for an extended period of time. In contrast, the impacts of environmental conditions in the deep sea on polymer properties and rigidity are virtually unknown. Here, we present unique results of plastic items identified to have been introduced into deep-sea sediments at a water depth of 4150 m in the eastern equatorial Pacific Ocean more than two decades ago. The results, including optical, spectroscopic, physical and microbial analyses, clearly demonstrate that the bulk polymer materials show no apparent sign of physical or chemical degradation. Solely the polymer surface layers showed reduced hydrophobicity, presumably caused by microbial colonization. The bacterial community present on the plastic items differed significantly (p < 0.1%) from those of the adjacent natural environment by a dominant presence of groups requiring steep redox gradients (Mesorhizobium, Sulfurimonas) and a remarkable decrease in diversity. The establishment of chemical gradients across the polymer surfaces presumably caused these conditions. Our findings suggest that plastic is stable over extended times under deep-sea conditions and that prolonged deposition of polymer items at the seafloor may induce local oxygen depletion at the sediment-water interface.

Effects of a deep-sea mining experiment on seafloor microbial communities and functions after 26 years.

Future supplies of rare minerals for global industries with high-tech products may depend on deep-sea mining. However, environmental standards for seafloor integrity and recovery from environmental impacts are missing. We revisited the only midsize deep-sea disturbance and recolonization experiment carried out in 1989 in the Peru Basin nodule field to compare habitat integrity, remineralization rates, and carbon flow with undisturbed sites. Plough tracks were still visible, indicating sites where sediment was either removed or compacted. Locally, microbial activity was reduced up to fourfold in the affected areas. Microbial cell numbers were reduced by ~50% in fresh "tracks" and by <30% in the old tracks. Growth estimates suggest that microbially mediated biogeochemical functions need over 50 years to return to undisturbed levels. This study contributes to developing environmental standards for deep-sea mining while addressing limits to maintaining and recovering ecological integrity during large-scale nodule mining.

Smoking status and its relationship with exercise capacity, physical activity in daily life and quality of life in physically independent, elderly individuals.

OBJECTIVE: To investigate the relationship between smoking status and exercise capacity, physical activity in daily life and health-related quality of life in physically independent, elderly (≥60 years) individuals. DESIGN: Cross-sectional, observational study. SETTING: Community-dwelling, elderly individuals. PARTICIPANTS: One hundred and fifty-four elderly individuals were categorised into four groups according to their smoking status: never smokers (n=57), passive smokers (n=30), ex-smokers (n=45) and current smokers (n=22). MAIN OUTCOME MEASURES: Exercise capacity [6-minute walk test (6MWT)], physical activity in daily life (step counting) and health-related quality of life [36-Item Short Form Health Survey (SF-36) questionnaire] were assessed. RESULTS: Current and ex-smokers had lower mean exercise capacity compared with never smokers: 90 [standard deviation (SD) 10] % predicted, 91 (SD 12) % predicted and 100 (SD 13) % predicted distance on 6MWT, respectively [mean differences -9.8%, 95% confidence intervals (CI) -17.8 to -1.8 and -9.1%, 95% CI -15.4 to -2.7, respectively; P<0.05 for both]. The level of physical activity did not differ between the groups, but was found to correlate negatively with the level of nicotine dependence in current smokers (r=-0.47, P=0.03). The median score for the mental health dimension of SF-36 was worse in passive {72 [interquartile range (IQR) 56 to 96] points} and current [76 (IQR 55 to 80) points] smokers compared with ex-smokers [88 (IQR 70 to 100) points] (median differences -16 points, 95% CI -22.2 to -3.0 and -12 points, 95% CI -22.8 to -2.4, respectively; P<0.05 for both). CONCLUSIONS: Among elderly individuals, current smokers had lower exercise capacity than never smokers. Although the level of physical activity did not differ between the groups, an association was found with smoking. Tobacco exposure was associated with worse scores for the mental health dimension of SF-36 in physically independent, elderly individuals.