| 1. |
- Wex, H., et al.
(författare)
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Connecting hygroscopic growth at high humidities to cloud activation for different particle types
- 2008
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 3:3, s. 35004-
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Tidskriftsartikel (refereegranskat)abstract
- This work recompiles studies that have been done with respect to hygroscopic growth in the regime of high relative humidities and with respect to activation for different kinds of particle at LACIS (Leipzig Aerosol Cloud Interaction Simulator) during the last few years. The particles examined consisted of a mixture of succinic acid and ammonium sulfate, seawater samples, soot coated with an organic and/or an inorganic substance, and two different atmospheric HULIS (HUmic LIke Substance) samples. An influence of changing non-ideal behavior and of slightly soluble substances on the hygroscopic growth was found in varying degrees in the subsaturation regime. The measured hygroscopic growth was extrapolated towards supersaturation, using a simple form of the Kohler equation, and assuming a constant number of molecules/ions in solution for high relative humidities (>= 95% or >= 98%, depending on the particles). When the surface tension of water was used, the modeled critical supersaturations reproduced the measured ones for the seawater samples and for the coated soot particles. To reach agreement between measured and modeled critical supersaturations for the HULIS particles, a concentration-dependent surface tension had to be used, with values of the surface tension that were lower than that of water, but larger than those that had been reported for bulk measurements in the past.
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| 2. |
- Destouni, Georgia, et al.
(författare)
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Nutrient cycling and N2O emissions in a changing climate: the subsurface water system role
- 2009
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 4:035008, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- This study has quantified the subsurface (groundwater, soil, sediment) water system role for hydrological nitrogen (N) and phosphorus (P) loading to the coast and agricultural N2O emissions to the atmosphere in a changing climate. Results for different climate and hydrological model scenarios in the Swedish Norrström drainage basin show that the subsurface water system may largely control a long-term increase in the coastal nutrient loading, in particular for P, irrespectively of the realized future climate change scenario and our uncertainty about it and its water flow effects. The results also indicate an important subsurface water system role for current atmospheric N2O emissions from agriculture, and an even greater role for future ones. The current N2O–N emissions from agriculture are quantified to be about 0.05 g m−2 yr−1 over the basin surface area, or 3% of the direct N mass application on the agricultural land. These results are consistent with recent global emission estimates, and show how the latter can be reconciled with previous, considerably smaller subsystem emission estimates made by the IPCC (Intergovernmental Panel on Climate Change).
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| 3. |
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| 4. |
- Pedersen, Eja, et al.
(författare)
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Wind turbines - low level noise sources interfering with restoration?
- 2008
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Ingår i: Environmental Research Letters. - Bristol : Institute of Physics Publishing (IOPP). - 1748-9326. ; 3:1, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- Wind turbines generate a low level noise and would thus not be expected to cause annoyance and disturb rest. In a society where people are being exposed to an increasing noise load, moderate and low level noise sources may also be perceived as annoying and hence inhibit restoration. This article presents an analysis of two socio-acoustic studies of wind turbine noise with the emphasis on perception, annoyance and consequences for restoration. It is hypothesized that low and moderate stressors such as wind turbine noise could have an impact on health. The risk seems to be higher if restoration is, or is perceived to be, impaired and also for certain groups of individuals. The observations warrant further studies.
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| 5. |
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| 6. |
- Walker, DA, et al.
(författare)
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Spatial and temporal patterns of greenness on the Yamal Peninsula, Russia : interactions of ecological and social factors affecting the Arctic normalized difference vegetation index
- 2009
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 4:4, s. 045004-
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Forskningsöversikt (refereegranskat)abstract
- The causes of a greening trend detected in the Arctic using the normalized difference vegetation index (NDVI) are still poorly understood. Changes in NDVI are a result of multiple ecological and social factors that affect tundra net primary productivity. Here we use a 25 year time series of AVHRR-derived NDVI data (AVHRR: advanced very high resolution radiometer), climate analysis, a global geographic information database and ground-based studies to examine the spatial and temporal patterns of vegetation greenness on the Yamal Peninsula, Russia. We assess the effects of climate change, gas-field development, reindeer grazing and permafrost degradation. In contrast to the case for Arctic North America, there has not been a significant trend in summer temperature or NDVI, and much of the pattern of NDVI in this region is due to disturbances. There has been a 37% change in early-summer coastal sea-ice concentration, a 4% increase in summer land temperatures and a 7% change in the average time-integrated NDVI over the length of the satellite observations. Gas-field infrastructure is not currently extensive enough to affect regional NDVI patterns. The effect of reindeer is difficult to quantitatively assess because of the lack of control areas where reindeer are excluded. Many of the greenest landscapes on the Yamal are associated with landslides and drainage networks that have resulted from ongoing rapid permafrost degradation. A warming climate and enhanced winter snow are likely to exacerbate positive feedbacks between climate and permafrost thawing. We present a diagram that summarizes the social and ecological factors that influence Arctic NDVI. The NDVI should be viewed as a powerful monitoring tool that integrates the cumulative effect of a multitude of factors affecting Arctic land-cover change.
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