Solar ultraviolet radiation in a changing climate

The projected large increases in damaging ultraviolet radiation as a result of global emissions of ozone-depleting substances have been forestalled by the success of the Montreal Protocol. New challenges are now arising in relation to climate change. We highlight the complex interactions between the drivers of climate change and those of stratospheric ozone depletion, and the positive and negative feedbacks among climate, ozone and ultraviolet radiation. These will result in both risks and benefits of exposure to ultraviolet radiation for the environment and human welfare. This Review synthesizes these new insights and their relevance in a world where changes in climate as well as in stratospheric ozone are altering exposure to ultraviolet radiation with largely unknown consequences for the biosphere

Origin, causes and effects of increased nitrite concentrations in aquatic environments

Literature frequently mentions increased nitrite concentrations along with its inhibitory effect towards bacteria and aquatic life. Nitrite accumulation has been studied for decades, and although numerous causal factors have already been commented on in literature, the mechanism of nitrite accumulation is not always clear. From the broad range of parameters and environmental factors reviewed in this paper, it is obvious that the causes and consequences of nitrite accumulation are not yet completely understood. Among others, pH, dissolved oxygen, volatile fatty acids, phosphate and reactor operation have been found to play a role in nitrite accumulation, which results from differential inhibition or disruption of the linkage of the different steps in both nitrification and denitrification. In the case of nitrification, this differential inhibition could lead to the displacement or unlinking of the ammonia oxidisers and nitrite oxidisers. In this paper, the idea is formulated that the nitrifier population forms a role model for the total microbial community. Increased nitrite concentrations would in this aspect not only signal a disruption of nitrifiers, but possibly also of the total configuration of the microbial community. [KEYWORDS: denitrification, nitrification, nitrite accumulation, nitrite toxicity]

Meta-analysis identifies common variants associated with body mass index in east Asians

10.1038/ng.1087Nature Genetics443307-311NGEN