Carbon fluxes from eroding peatlands – the carbon benefit of revegetation following wildfire

Peatlands are among the largest long‐term soil carbon stores, but their degradation can lead to significant carbon losses. This study considers the carbon budget of peat‐covered sites after restoration, following degradation by past wildfires. The study measured the carbon budget of eight sites: four restored‐revegetated sites, two unrestored bare soil control sites, and two intact vegetated controls over two years (2006–2008). The study considered the following flux pathways: dissolved organic carbon (DOC); particulate organic carbon (POC); dissolved carbon dioxide (CO₂); primary productivity; net ecosystem respiration, and methane (CH₄). The study shows that unrestored, bare peat sites can have significant carbon losses as high as 522 ± 3 tonnes C/km²/yr. Most sites showed improved carbon budgets (decreased source and/or increased sink of carbon) after restoration; this improvement was mainly in the form of a reduction in the size of the net carbon source, but for one restored site the measured carbon budget after four years of restoration was greater than observed for vegetated controls. The carbon sequestration benefit of peatland restoration would range between 122 and 833 tonnes C/km²/yr. Copyright © 2011 John Wiley & Sons, Ltd.     

Interstellar Refractive Scintillation and Intraday Polarization Angle Swings

Intraday polarization angle swings of ~180° observed in two sources (QSO 0917+624 and QSO 1150+812) are discussed in the framework of refractive interstellar scintillation by a continuous interstellar medium. Model-fits to the I-, Q- and U- light curves were made for both sources. It is shown that for the case of 0917+624 both the intraday intensity variations and the polarization angle swing of ~180° could be explained consistently in     

Influence of Biogenic Secondary Organic Aerosol Formation Approaches on Atmospheric Chemistry

Global secondary organic aerosol formation (SOA) is currently assumed to be between 11.2 and 270 Tg/yr. This range of uncertainty is reflected in the gas-phase chemistry. In this study, we focus on the feedback of SOA formation on the concentrations of most important trace gases such as ozone, and compare it to the impact of monoterpene gas-phase chemistry with a newly developed reduced monoterpene mechanism (MMM) for either α- or β-pinene in the global chemistry transport model MATCH-MPIC. With this set-up an uncertainty range of 3.5–4.0% increase in annually averaged tropospheric ozone was found to be caused by the gas-phase chemistry of the investigated monoterpenes. Moreover, a strong feedback has been observed for NO_x, HCHO, HNO₃ and PAN. These observations are affected remarkably by different SOA formation approaches like partitioning or saturation vapour pressure limitation and by the structure of the monoterpene used, e.g. reducing the impact on tropospheric ozone to 1.2–1.9% by using the partitioning approach versus the simulation with gas-phase chemistry only. Therefore, a consideration of the individual processes associated with SOA formation seems to be necessary to reduce the uncertainty in SOA formation and to understand the impact of VOCs on atmospheric chemistry. An erratum to this article is available at .     

Earthquake early warning for transport lines

This paper analyzes the potential of earthquake early-warning systems for transport lines. The interdisciplinary work focuses on rapidly producing an alert map during an ongoing earthquake as well as providing a damage map immediately after the strong-motion phase that visualizes potential damages to the railway infrastructure. In order to meet these application requirements, a service-oriented architecture based on geospatial standards is specified. This ensures the portability of the system architecture to different geographic regions as well as a potential transfer to other natural disasters and infrastructure systems. The first part of the paper describes the standard-based services of the system architecture together with design principles that are useful for the realization of early-warning systems. In the second part of the paper, an online demonstrator for the exemplary test area in the federal state of Baden-Württemberg, Germany, is presented. The system architecture of the demonstrator includes an earthquake early-warning methodology based on artificial neural networks and an infrastructure-specific damage assessment. The third part of the paper analyzes the potential of implementing low-cost sensors in the track, which would provide a dense network directly at the railway infrastructure.