| 1. |
- Asmi, A., et al.
(författare)
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Aerosol decadal trends - Part 2: In-situ aerosol particle number concentrations at GAW and ACTRIS stations
- 2013
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7324. ; 13:2, s. 895-916
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Tidskriftsartikel (refereegranskat)abstract
- We have analysed the trends of total aerosol particle number concentrations (N) measured at long-term measurement stations involved either in the Global Atmosphere Watch (GAW) and/or EU infrastructure project ACTRIS. The sites are located in Europe, North America, Antarctica, and on Pacific Ocean islands. The majority of the sites showed clear decreasing trends both in the full-length time series, and in the intra-site comparison period of 2001-2010, especially during the winter months. Several potential driving processes for the observed trends were studied, and even though there are some similarities between N trends and air temperature changes, the most likely cause of many northern hemisphere trends was found to be decreases in the anthropogenic emissions of primary particles, SO2 or some co-emitted species. We could not find a consistent agreement between the trends of N and particle optical properties in the few stations with long time series of all of these properties. The trends of N and the proxies for cloud condensation nuclei (CCN) were generally consistent in the few European stations where the measurements were available. This work provides a useful comparison analysis for modelling studies of trends in aerosol number concentrations.
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| 2. |
- Manninen, H. E., et al.
(författare)
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EUCAARI ion spectrometer measurements at 12 European sites - analysis of new particle formation events
- 2010
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 10:16, s. 7907-7927
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Tidskriftsartikel (refereegranskat)abstract
- We present comprehensive results on continuous atmospheric cluster and particle measurements in the size range similar to 1-42 nm within the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) project. We focused on characterizing the spatial and temporal variation of new particle formation events and relevant particle formation parameters across Europe. Different types of air ion and cluster mobility spectrometers were deployed at 12 field sites across Europe from March 2008 to May 2009. The measurements were conducted in a wide variety of environments, including coastal and continental locations as well as sites at different altitudes (both in the boundary layer and the free troposphere). New particle formation events were detected at all of the 12 field sites during the year-long measurement period. From the data, nucleation and growth rates of newly formed particles were determined for each environment. In a case of parallel ion and neutral cluster measurements, we could also estimate the relative contribution of ion-induced and neutral nucleation to the total particle formation. The formation rates of charged particles at 2 nm accounted for 1-30% of the corresponding total particle formation rates. As a significant new result, we found out that the total particle formation rate varied much more between the different sites than the formation rate of charged particles. This work presents, so far, the most comprehensive effort to experimentally characterize nucleation and growth of atmospheric molecular clusters and nanoparticles at ground-based observation sites on a continental scale.
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| 3. |
- Spracklen, D. V., et al.
(författare)
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Explaining global surface aerosol number concentrations in terms of primary emissions and particle formation
- 2010
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 10:10, s. 4775-4793
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Tidskriftsartikel (refereegranskat)abstract
- We synthesised observations of total particle number (CN) concentration from 36 sites around the world. We found that annual mean CN concentrations are typically 300-2000 cm(-3) in the marine boundary layer and free troposphere (FT) and 1000-10 000 cm(-3) in the continental boundary layer (BL). Many sites exhibit pronounced seasonality with summer time concentrations a factor of 2-10 greater than wintertime concentrations. We used these CN observations to evaluate primary and secondary sources of particle number in a global aerosol microphysics model. We found that emissions of primary particles can reasonably reproduce the spatial pattern of observed CN concentration (R-2=0.46) but fail to explain the observed seasonal cycle (R-2=0.1). The modeled CN concentration in the FT was biased low (normalised mean bias, NMB=-88%) unless a secondary source of particles was included, for example from binary homogeneous nucleation of sulfuric acid and water (NMB=-25%). Simulated CN concentrations in the continental BL were also biased low (NMB=-74%) unless the number emission of anthropogenic primary particles was increased or a mechanism that results in particle formation in the BL was included. We ran a number of simulations where we included an empirical BL nucleation mechanism either using the activation-type mechanism (nucleation rate, J, proportional to gas-phase sulfuric acid concentration to the power one) or kinetic-type mechanism (J proportional to sulfuric acid to the power two) with a range of nucleation coefficients. We found that the seasonal CN cycle observed at continental BL sites was better simulated by BL particle formation (R-2=0.3) than by increasing the number emission from primary anthropogenic sources (R-2=0.18). The nucleation constants that resulted in best overall match between model and observed CN concentrations were consistent with values derived in previous studies from detailed case studies at individual sites. In our model, kinetic and activation-type nucleation parameterizations gave similar agreement with observed monthly mean CN concentrations.
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| 4. |
- Paasonen, P., et al.
(författare)
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On the roles of sulphuric acid and low-volatility organic vapours in the initial steps of atmospheric new particle formation
- 2010
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 10:22, s. 11223-11242
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Tidskriftsartikel (refereegranskat)abstract
- Sulphuric acid and organic vapours have been identified as the key components in the ubiquitous secondary new particle formation in the atmosphere. In order to assess their relative contribution and spatial variability, we analysed altogether 36 new particle formation events observed at four European measurement sites during EUCAARI campaigns in 2007-2009. We tested models of several different nucleation mechanisms coupling the formation rate of neutral particles (J) with the concentration of sulphuric acid ([H2SO4]) or low-volatility organic vapours ([org]) condensing on sub-4 nm particles, or with a combination of both concentrations. Furthermore, we determined the related nucleation coefficients connecting the neutral nucleation rate J with the vapour concentrations in each mechanism. The main goal of the study was to identify the mechanism of new particle formation and subsequent growth that minimizes the difference between the modelled and measured nucleation rates. At three out of four measurement sites - Hyytiala (Finland), Melpitz (Germany) and San Pietro Capofiume (Italy) - the nucleation rate was closely connected to squared sulphuric acid concentration, whereas in Hohenpeissenberg (Germany) the low-volatility organic vapours were observed to be dominant. However, the nucleation rate at the sulphuric acid dominant sites could not be described with sulphuric acid concentration and a single value of the nucleation coefficient, as K in J=K [H2SO4](2), but the median coefficients for different sites varied over an order of magnitude. This inter-site variation was substantially smaller when the heteromolecular homogenous nucleation between H2SO4 and organic vapours was assumed to take place in addition to homogenous nucleation of H2SO4 alone, i.e., J=K-SA1[H2SO4](2)+K-SA2[H2SO4][org]. By adding in this equation a term describing homomolecular organic vapour nucleation, K-s3[org](2), equally good results were achieved. In general, our results suggest that organic vapours do play a role, not only in the condensational growth of the particles, but also in the nucleation process, with a site-specific degree.
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| 5. |
- Cinner, Joshua E., et al.
(författare)
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Comanagement of coral reef social ecological systems
- 2012
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 109:14, s. 5219-5222
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Tidskriftsartikel (refereegranskat)abstract
- In an effort to deliver better outcomes for people and the ecosystems they depend on, many governments and civil society groups are engaging natural resource users in collaborative management arrangements (frequently called comanagement). However, there are few empirical studies demonstrating the social and institutional conditions conducive to successful comanagement outcomes, especially in small-scale fisheries. Here, we evaluate 42 comanagement arrangements across five countries and show that: (i) comanagement is largely successful at meeting social and ecological goals; (ii) comanagement tends to benefit wealthier resource users; (iii) resource overexploitation is most strongly influenced by market access and users' dependence on resources; and (iv) institutional characteristics strongly influence livelihood and compliance outcomes, yet have little effect on ecological conditions.
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| 6. |
- Westervelt, D. M., et al.
(författare)
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Formation and growth of nucleated particles into cloud condensation nuclei : model-measurement comparison
- 2013
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 13:15, s. 7645-7663
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Tidskriftsartikel (refereegranskat)abstract
- Aerosol nucleation occurs frequently in the atmosphere and is an important source of particle number. Observations suggest that nucleated particles are capable of growing to sufficiently large sizes that they act as cloud condensation nuclei (CCN), but some global models have reported that CCN concentrations are only modestly sensitive to large changes in nucleation rates. Here we present a novel approach for using long-term size distribution observations to evaluate a global aerosol model's ability to predict formation rates of CCN from nucleation and growth events. We derive from observations at five locations nucleation-relevant metrics such as nucleation rate of particles at diameter of 3 nm (J(3)), diameter growth rate (GR), particle survival probability (SP), condensation and coagulation sinks, and CCN formation rate (J(100)). These quantities are also derived for a global microphysical model, GEOS-Chem-TOMAS, and compared to the observations on a daily basis. Using GEOS-Chem-TOMAS, we simulate nucleation events predicted by ternary (with a 10(-5) tuning factor) or activation nucleation over one year and find that the model slightly understates the observed annual-average CCN formation mostly due to bias in the nucleation rate predictions, but by no more than 50% in the ternary simulations. At the two locations expected to be most impacted by large-scale regional nucleation, Hyytiala and San Pietro Capofiume, predicted annual-average CCN formation rates are within 34 and 2% of the observations, respectively. Model-predicted annual-average growth rates are within 25% across all sites but also show a slight tendency to underestimate the observations, at least in the ternary nucleation simulations. On days that the growing nucleation mode reaches 100 nm, median single-day survival probabilities to 100 nm for the model and measurements range from less than 1-6% across the five locations we considered; however, this does not include particles that may eventually grow to 100 nm after the first day. This detailed exploration of new particle formation and growth dynamics adds support to the use of global models as tools for assessing the contribution of microphysical processes such as nucleation to the total number and CCN budget.
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| 7. |
- Cinner, J. E., et al.
(författare)
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Transitions toward co-management : The process of marine resource management devolution in three east African countries
- 2012
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Ingår i: Global Environmental Change. - : Elsevier BV. - 0959-3780 .- 1872-9495. ; 22:3, s. 651-658
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Tidskriftsartikel (refereegranskat)abstract
- Communities are increasingly empowered with the ability and responsibility of working with national governments to make decisions about marine resources in decentralized co-management arrangements. This transition toward decentralized management represents a changing governance landscape. This paper explores the transition to decentralisation in marine resource management systems in three East African countries. The paper draws upon expert opinion and literature from both political science and linked social-ecological systems fields to guide exploration of five key governance transition concepts in each country: (1) drivers of change; (2) institutional arrangements; (3) institutional fit; (4) actor interactions; and (5) adaptive management. Key findings are that decentralized management in the region was largely donor-driven and only partly transferred power to local stakeholders. However, increased accountability created a degree of democracy in regards to natural resource governance that was not previously present. Additionally, increased local-level adaptive management has emerged in most systems and, to date, this experimental management has helped to change resource user's views from metaphysical to more scientific cause-and-effect attribution of changes to resource conditions. (C) 2012 Elsevier Ltd. All rights reserved,
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| 8. |
- el-Din, Sayed H. Seif, et al.
(författare)
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Potential effect of the medicinal plants Calotropis procera, Ficus elastica and Zingiber officinale against Schistosoma mansoni in mice
- 2014
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Ingår i: Pharmaceutical Biology. - : Informa UK Limited. - 1744-5116 .- 1388-0209. ; 52:2, s. 144-150
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Tidskriftsartikel (refereegranskat)abstract
- Context: Calotropis procera (Ait.) R. Br. (Asclepiadaceae), Ficus elastica Roxb. (Moraceae) and Zingiber officinale Roscoe (Zingiberaceae) have been traditionally used to treat many diseases. Objective: The antischistosomal activity of these plant extracts was evaluated against Schistosoma mansoni. Materials and methods: Male mice exposed to 80 +/- 10 cercariae per mouse were divided into two batches. The first was divided into five groups: (I) infected untreated, while groups from (II-V) were treated orally (500 mg/kg for three consecutive days) by aqueous stem latex and flowers of C. procera, latex of F. elastica and ether extract of Z. officinale, respectively. The second batch was divided into four comparable groups (except Z. officinale-treated group) similarly treated as the first batch in addition to the antacid ranitidine (30 mg/kg) 1 h before extract administration. Safety, worm recovery, tissues egg load and oogram pattern were assessed. Results: Calotropis procera latex and flower extracts are toxic (50-70% mortality) even in a small dose (250 mg/kg) before washing off their toxic rubber. Zingiber officinale extract insignificantly decrease (7.26%) S. mansoni worms. When toxic rubber was washed off and ranitidine was used, C. procera (stem latex and flowers) and F. elastica extracts revealed significant S. mansoni worm reductions by 45.31, 53.7 and 16.71%, respectively. Moreover, C. procera extracts produced significant reductions in tissue egg load (similar to 34-38.5%) and positively affected oogram pattern. Conclusion: The present study may be useful to supplement information with regard to C. procera and F. elastica antischistosomal activity and provide a basis for further experimental trials.
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| 9. |
- Hamed Abd El Mageed, Yasser, et al.
(författare)
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Assessment of heavy metals pollution and microbial contamination in water, sediments and fish of Lake Manzala, Egypt
- 2013
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Ingår i: Life Science Journal: Acta Zhengzhou University Overseas Edition. - 1097-8135. ; 10:1, s. 86-99
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study is to assess the heavy metals pollution and microbial contamination in water, sediments and fish of Lake Manzala and study the direct and indirect effect for disposal of waste water, industrial and agricultural drainage water into the lake on the environmental situation. Samples were collected from four different sites in the lake and one site in the drain. The selected sites are exposed to direct and indirect industrial, municipal waste water and agricultural drainage disposals. A site near the connection between the lake and the sea was chosen as a possible unpolluted site to compare. Three water samples and one sediment sample were collected monthly from each site for thirteen months. Fish samples (Oreochromis niloticus) were collected randomly for eight months from different sites of the lake. Water salinity and pH values were measured to each site. Water, sediment and fish samples were analyzed for the concentration of five major heavy metals (Mn, Cd, Zn, Pb and Cu), and two groups of bacteria (Total viable bacteria TVB - faecal coliform bacteria FCB). Results show that all the water and sediment samples were collected from five sites contain different concentration of the five tested heavy metals. The highly polluted site with Zn, Pb, Cu in sediment was found in the drain as a result of the industrial disposal. The highly polluted site with Zn and Cu in water and Cd in sediment was found in site near the industrial area as a result of direct disposal of factories nearby. Although the site near the connection between the sea and the lake was assumed to be the purest site, It was found contained a maximum concentration of Pb in water. It is possibly due to the disposal from a new natural gas factories located near this area. All the five sites were contaminated with high rate of TVB and FCB in water which is an indicator of untreated waste water which spilled directly or indirectly to the lake. The most alarming result was found when analyzing fish; all the fish samples were contaminated on surface and internally with very high amounts of TVB and FCB at gill and intestine. Fish samples also had high concentrations of analyzed heavy metals at their flesh. The mean calculated value of Pb was high up to 38 times than the allowed permissible concentration. This confirms that lake fish is highly polluted and dangerous for human health.
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| 10. |
- Hamid Muhammed, Hamed, 1967-, et al.
(författare)
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Temperaturvariationsanalys för hudcancerscreening, Poster, Barncancerfondens tredje konferens
- 2013
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Ingår i: Barncancerfondens tredje konferens: Medicinsk Teknik för Barn med Cancer.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Den här studien visar att det är möjligt att detektera tydliga temperaturskillnader mellan cancervävnad och frisk vävnad. Detta kan vara ett resultat av både angiogenes (processen som leder till nybildning av blodkärl från de minsta befintliga blodkärl) och ökad ämnesomsättning hos cancerceller (medan cancertumörer formas) jämfört med friska normala celler, som ändrar och ökar intensiteten av den termiska IR-strålningen inom cancervävnads områden. Temperaturförändringarna detekterades genom mätningar av termisk IR-strålning inom våglängdsområdet 8-14 μm. Intensiva experiment utfördes på möss med hudcancer. Cancerområdet hade i genomsitt 0.3 – 0.5 °C högre temperatur än de friska grannområdena. Både kvalitativa och kvantitativa statistiska metoder användes för att analysera dessa mätningar. Analysresultaten verifierar användbarheten av att mäta termisk IR-strålning för att kunna detektera hudcancerområden.
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