bluuebunny/crossref_metadata_2025 huggingface dataset:
Implementation of a Nurse-Driven Burn Resuscitation Protocol: A Quality Improvement Project
Authors: Fahlstrom Kyra , Boyle Cameron , Makic Mary Beth Flynn
Published: February 2013

Background

Burn resuscitation, including titration of fluids and administration of colloids, is often driven by physicians’ orders. Inconsistencies in burn resuscitation cause overresuscitation, which has adverse consequences.

Methods

Retrospective chart reviews were completed to evaluate fluid resuscitation and complications for 12 months before and after development and implementation of a nurse-driven burn resuscitation protocol.

Results

Before implementation of the protocol, results at 24 hours after injury indicated that 58% of patients were overresuscitated, had a serum level of lactate of at least 2 mmol/L (100%), and had complications (pulmonary edema 20%, abdominal compartment syndrome 7%, acute lung injury/acute respiratory distress syndrome 30%) within the first 5 days. Two outcomes differed from before to after implementation of the protocol: serum level of lactate at 24 hours (t37.8 =2.38, P =.007) and central venous pressure at 48 hours (t31 =2.27, P =.03). After implementation of the protocol, no patients had abdominal compartment syndrome develop.

Conclusions

Implementation of the nurse-driven burn resuscitation protocol improved nurses’ awareness and assessment of fluid status during resuscitation and improved patients’ outcomes.
Acute Liver Failure in an Obstetric Patient: Challenge of Critical Care for 1 Patient With 2 Subspecialty Needs
Authors: Castello Holly , Schoch Lisa , Grogan Tracy A.
Published: February 2013

Acute fatty liver of pregnancy is a rare and life-threatening disease associated with a defect in fatty acid metabolism in the fetus that causes liver disease in the mother. Prompt diagnosis and management are critical to the outcome of both the mother and the fetus and require involvement of several medical specialties, including hepatology, obstetrics, and, possibly, critical care. The included case study describes a woman with acute fatty liver of pregnancy decompensating to acute liver failure complicated by encephalopathy, cerebral edema, and intracranial hypertension. Subsequent management of these conditions, including the woman’s progression to liver transplant, is provided.
Surficial geochemistry and response to volcanic-hosted massive sulphide mineralization in the Snow Lake region
Authors: Kaszycki C A , Nielsen E , Gobert G
Published: February 2013

A primary objective of the till geochemistry program was to develop new approaches for the identification of volcanic-hosted massive sulphide deposits (VHMS) and associated alteration zones. In the Chisel Lake area, detailed multi-media sampling was designed to
evaluate the geochemical response of various soil horizons and sample media (C- and B-horizon till, humus), sample size fractions thereof, and different analytical methods. The geochemical expression of mineralization was found to vary dramatically with sample type and soil horizon, ranging from
patterns that reflect glacial transport and erosion (C-horizon till), to hydromorphic and biogenic dispersion (B-horizon till and humus), and anthropogenic contamination (humus).

At the regional scale, the most pronounced geochemical trend occurs in the area southwest of the town of Snow Lake and northeast of the Chisel Lake mine. In this region, a multi-element Cu, Hg, Pb, As, Au, and Sn anomaly occurs immediately north of the Chisel Lake mine and extends northward to the
south shore of Snow Lake, encompassing the recently developed Photo Lake deposit. High ratios of Cu/Zn in C-horizon till samples were found to closely reflect those felsic horizons that host Cu-rich volcanic-hosted massive sulphide deposits (Anderson, Rod, and Stall). Conversely, high ratios of
Zn/Cu in C-horizon till samples were found to closely reflect Zn-rich mineralization at the Chisel Lake/Lost Lake/Ghost Lake deposits and also, somewhat surprisingly, at the Cu-rich Linda 2 deposit.
Phase selective leaches for use in exploration geochemistry
Authors: Hall G E M , Vaive J E , Beer R , Hoashi M
Published: February 2013

This paper describes the development and evaluation of a sequential extraction scheme for application to soils, tills, and surficial sediments to elucidate the form(s) in which an element is held and hence to provide information as to its genesis. The
operationally defined phases selected for extraction have been assigned the following categories: adsorbed/exchangeable/carbonate, þAEC'; amorphous Fe oxyhydroxide, þam Fe ox'; crystalline Fe oxide, þcry Fe ox'; sulphides and organics; and residual, mainly silicates. Particular attention has been
paid to the specificity of the hydroxylamine reagent, 0.25 M NH2OH.HCl in 0.25 M HCl, for extraction of the þam Fe ox' phase, well recognized for its scavenging properties of trace metals in the surficial environment. A decrease in the acid strength to 0.05 M HCl in this leach lessens the solubility
of sphalerite and galena to <1% but a major portion of the humate and fulvate component in a sediment is dissolved, regardless of HCl concentration.

Other reagents used in this scheme comprise: 1 M CH3COONa for þAEC'; 1 M NH2OH.HCl in 25% CH3COOH for þcry Fe ox'; KClO3/HCl followed by HNO3 for sulphides and organics; and finally HF-HClO4-HNO3-HCl for the residual minerals. Typical long-term precision values are provided in the data obtained
by replicate application of these five leaches to the international standard reference materials TILL-1, TILL-2, TILL-3, TILL-4, and LKSD-4, for the elements Zn, Cu, Pb, Ni, Co, Mn, and Fe.
Selective leaching of the labile organic component of humus and soils with sodium pyrophosphate solution
Authors: Hall G E M , Vaive J E , MacLaurin A I , Hoashi M
Published: February 2013

The effectiveness of the 0.1 M Na4P2O7 leach commonly used in soil science to extract humic and fulvic acid components was studied for application to humus samples collected in exploration geochemistry programs. A 1 h extraction of 1 g of sample by 100 mL of this
reagent was found to leach about 80-90% of Co, Cu, Ni, Pb and Zn associated with this labile organic phase, with precision typically in the range 5-10% relative standard deviation. Longer extraction time led to readsorption of Ni onto the sample substrate and did not result in higher
concentrations of other elements. A second 1 h extraction tended to release proportionately more Mn (and to a lesser degree, Fe) than other elements such as Cu and organic C. This probably reflects dispersion of colloidal Mn particles rather than dissolution of organically bound Mn and could be
minimized by ultracentrifugation of the leachate prior to analysis.

Detection limits in the order of 1 ppm for these elements in the original sample by atomic absorption spectrometry would be improved by one to two orders of magnitude by flow injection inductively coupled plasma mass spectrometry. The latter technique requires dilution of the leachate by about
20-fold to obviate severe drift due to salt build-up on the sampling orifice, even with the use of flow injection.
Ground electromagnetic, magnetic, and VLF-EM surveys at four sites near Snow Lake
Authors: Sinha A K , Palacky G J
Published: February 2013

Ground electromagnetic (EM) and magnetic surveys were conducted over four major volcanogenic massive sulphide occurrences in the Snow Lake greenstone belt, Manitoba, as part of the EXTECH I Project. The purpose of the survey was to measure typical EM and magnetic
signatures over these deposits, interpret the results in terms of the electrical and magnetic properties of the sulphides and the host rock, and compare the results with rock properties of drill core and hand specimen samples of sulphides in the laboratory. A multifrequency, multiseparation
horizontal-loop EM survey was used at three sites, and the ground VLF-EM method was used at the fourth site to determine the conductivity characteristics of the sulphide bodies and the host rocks. Magnetic characteristics of the deposits were obtained by interpreting total field and vertical
magnetic gradient survey data.

Despite differences in geological setting and mineralogical compositions, the investigation showed that all four sulphide deposits are poorly conductive (conductances from 0.1 to 2 S). Some conductors are distinctively magnetic, while others have little magnetic association. Such characteristics are
unlike those observed in other Precambrian greenstone belts, where sulphide deposits are highly conductive and usually have some association with magnetic minerals. The results of this study could have important significance for future mineral exploration in the Snow Lake
area.
Electrical properties of disseminated sulphide ore samples from Snow Lake
Authors: Katsube T J , Palacky G J , Sangster D F , Galley A G , Scromeda N
Published: February 2013

Electrical characteristics (resistivity and formation factor) of seven samples (15 specimens), representing various sulphide mineralization types in the Flin Flon-Snow Lake volcanic belt, have been investigated. The purpose of the study was to seek an explanation
for the weaker than expected electromagnetic (EM) responses of the sulphide bodies in this region.

Results indicate that resistivities of many of the samples are 10-2,100 W.m, much higher than the typical range of massive sulphide bodies (0.01-1 W.m), and above the conventional detection limit (10 W.m) of surface EM survey systems. In addition, surprisingly strong resistivity anisotropy (high as
45:1 to 70:1) has been observed in some of the samples, resulting in one of the directions displaying resistivities (2 W.m) within the conventional EM survey system detection limit, but other directions (40-100 W.m) displaying values well above those limits. These results may explain the reason for
the limited success of some past EM surveys, and indicate that they were poorly designed for anisotropic low-resistivity targets. It is suggested that either broadband systems with at least one coil pair operating in the 30 to 60 kHz range, or time domain EM systems with an in-pulse channel may
offer greater success in detecting these anisotropic conductors.
The needs of health promoters on a health promotion programme for families with adolescents orphaned by HIV and AIDS
Authors: Mthobeni Maseapo P. , Peu Mmapheko D.
Published: February 2013

The South African communities has shown to have a challenge in accessing health services especially in rural areas; hence the national strategic objective 1.7 aimed at strengthening community systems to expand access to services using the community-based care programmes (NSP 2012–2016). The programmes enhance access to health services whilst promoting health and educating the community to improve health knowledge and work towards attaining a healthy living (NSP 2012–2016). However, the health promoters from the rural Hammanskraal region in the North West Province of South Africa often found themselves rendering the health promotion services in their communities with limited resources. This study aimed at exploring and describing the challenges faced by health promoters in implementing health promotion programmes for families with adolescents orphaned by HIV and AIDS. The study followed a qualitative design. Data was collected using focus group interviews. Participants were purposely selected by the social worker and the health promotion coordinator working at Hammanskraal. The process of data analysis was adapted from the eight steps of Tesch method of data analysis where categories, sub-categories and themes were isolated. The following categories emerged as the needs of health promoters on health promotion programmes for families with adolescents orphaned by HIV and AIDS, (1) financial needs, (2) resources, (3) basic life needs, (4) educational needs and (5) health promoter’s needs. It is therefore recommended that equal distribution of resources: including medicine, equipment and finances, should be maintained in order to ensure non-interrupted services.
Mechanical thrombectomy devices for endovascular management of acute ischemic stroke: Duke stroke center experience
Authors: Agrawal Abhishek , Golovoy David , Nimjee Shahid , Ferrell Andrew , Smith Tony , Britz Gavin
Published: February 2013

Background: Mechanical thrombectomy devices are gaining popularity in large vessel occlusions where chemical thrombolysis is usually futile. MERCI, Multi-MERCI, Penumbra and SWIFT trails have elevated the status of mechanical thrombectomy from being a complementary treatment modality to mainstream stroke intervention. The aim of this study was to compare our immediate recanalization rates with available mechanical devices. Materials and Methods: A retrospective review from March 2009 to August 2012 was performed on patients who underwent mechanical thrombectomy for large vessel occlusion. Cases where IATPA and/or balloon angioplasty was performed without mechanical thrombectomy were excluded from the study. Recanalization rates were assessed immediately post-procedure by follow-up angiography. TICI scores were used to quantify the extent of recanalization and the residual clot burden. Results: Twenty two procedures were performed on 20 patients using Merci (MER):5; Penumbra (PEN):11; Solitaire-FR (SOL):6. Two patients underwent intervention using both Merci and Penumbra devices. The M:F ratio was 1.2:1. The most common vascular territory involved was the right MCA (9/20) followed by left MCA (5/20), left ICA (2/20), basilar (3/20) and vertebral arteries (1/20). The average door to needle time was 210 minutes [MER: 184.4; PEN: 249.2; SOL: 162]. Additional procedures were performed in 63.4% (14/22) of the patients [MER: 80% (4/5); PEN: 72.7% (8/11) and SOL: 33.3% (2/6)]. Vasospasm was observed in MER: 20% (1/5); PEN: 9.1% (1/11); SOL: 0% (0/6)]. Complete recanalization was achieved in 59.1% (13/22) [MER: 40% (2/5); PEN: 45.5% (5/11); SOL: 100% (6/6)]. The rate of complete recanalization was statistically significant for the Solitaire group vs. the MERCI group ( P=0.0062) as well as the Penumbra group (0.0025). The average pre-procedure TICI was 0.4 [MER: 0.6; PEN: 0.3; SOL: 0.3], while the average post-procedure TICI was 2.5 [MER: 2.4; PEN: 2.3; SOL: 3.0]. Conclusions: The study reveals a higher rate of angiographic recanalization using the Solitaire-FR device, requiring a lesser number of passes and other associated procedures as compared to MERCI and Penumbra. Thus, Stentrievers (Solitaire-FR) are advantageous in faster device delivery and quick flow restoration. However, future prospective randomized large trials are required to confirm these early results.
AVM Compartments: Do they modulate trasnidal pressures? An electrical network analysis
Authors: Litao Miguel , Pilar-Arceo Carlene , Legaspi Gerardo
Published: February 2013

Background: Arteriovenous malformation (AVM) compartments are thought as independently fed, hemodynamically independent components of the AVM nidus. Its possible role in modulating transnidal pressures have not been investigated to our knowledge. Objective: To investigate if AVM compartments play a role in modulating transnidal pressures by using electrical models as a method of investigation. Materials and Methods: Monocompartmental and multicompartmental AVM models were constructed using electrical circuits- building on Dr. Guglielmi's previous work. Each compartment was fed by two feeding arteries (resistors) and had a shared draining vein with other compartments in the AVM nidus. Each compartment is composed of a series of resistors which represents the pressure gradient along the AVM (arterial, arteriolar, venular, and venous). Pressure (voltage) readings were obtained within these nidal points. Results: The pressure gradient (venous-arterial) is more as there are less AVM compartments in the nidus model. The monocomparmental model had a pressure gradient of 66mmHg (V); while it was 64, 61, and 59 for the 2-, 3-, and 4-compartment models, respectively. In addition, the more the number of compartments, the greater the flow (mA) is in the whole AVM nidus, 33 ml/min for the monocompartmental AVM and 121ml/min for the 4-compartment AVM; though there was greater flow per compartment as there were less compartments, 33ml/min per compartment for the monocompartmental model versus 29ml/min for the 4-compartment model. Conclusion: Transnidal pressure gradients may be less the more compartments an AVM has. This electrical model represents an approach that can be used in investigating the hemodynamic contributions of AVM compartments.
Results of surgical excision of cirsoid aneurysm of the scalp without preoperative interventions
Authors: El Shazly Ayman , Saoud Khaled
Published: February 2013

Context: Cirsoid aneurysms of scalp are rare lesions which are mainly treated by surgical excision. Endovascular embolization was described either alone or prior to surgery in order to minimize the risk of bleeding. However, the endovascular therapy also carries the risk of scalp necrosis, escape of embolization material to circulation, and recurrence of the lesion. Aim: To evaluate the results of well-planned classic surgical excision of cirsoid aneurysm. Study Design: This is a retrospective case series study. Materials and Methods: This is a retrospective case series study on nine patients with cirsoid aneurysms who were treated with surgical excision. Preoperative Planning for location, size, feeding arteries, and venous drainage of the lesions were done by plain and contrast enhanced CT, MRI, MR angiogram, and selective internal and external carotid angiograms. Complete surgical excision for the lesions was done. Postoperative evaluation of excision was done by cranial magnetic resonance angiography in all the patients. The mean follow up period was 34.1 (±7.62 STD) months. Results: The lesion was located in the occipital region in three (33.3%) cases, frontal region in two (22.2%) cases, temproparietal region in two (22.2%) cases, parietal region in one case (11.1%), and vertex in one case (11.1%). The superficial temporal artery was involved in seven (77.8%) cases, the occipital artery was involved in six (66.7%) cases, the posterior auricular artery was involved in five (55.6%) cases, the supraorbital artery was involved in two (22.2%) cases and the middle meningeal artery was involved in two (22.2%) cases. Total excision of the lesion was achieved in eight patients and en bloc resection and primary closure was done in one patient . Postoperative magnetic resonance angiogram showed no residual lesion in all patients. No postoperative complication related to the surgery had occurred. No recurrence had occurred during the follow-up period (mean 34.1 ± 7.62 STD months). Conclusion: Well-planned surgery of cirsoid aneurysm of the scalp without preoperative interventions could achieve complete excision of the lesion without any residual masses or recurrence and with a low incidence of complications.
Primary intracranial germ cell tumors
Authors: Mufti Shagufta , Jamal Awatif
Published: February 2013

Background: Primary intracranial germ cell tumors are rare (ICGCTs) and usually localized in the pineal and suprasellar regions of the brain. They are divided into histologic types: Germinoma, teratoma choriocarcinoma, embryonal carcinoma, yolk sac tumor, and malignant mixed germ cell tumors (MMGCTs). Neuroimaging evaluation is useful to distinguish between the types of ICGCTs. Germinoma is highly sensitive to radiotherapy or/and chemotherapy, and is potentially curable without surgery. MMGCTs are treated with the combination of chemotherapy and radiation, with a poorer prognosis. ICGCTs warrant correct pre-operative diagnosis in order to decide on appropriate management. Aim: To report the clinicopathological and immunohistochemical findings in three cases of primary intracranial germ-cell tumor . Materials and Methods: Three cases of intracranial germ cell tumors inclusive of both genders and all brain regions were retrieved from the archives of the Anatomical Pathology Department at King Abdul Aziz University Hospital, Jeddah between the years, 1995-2011, through a computerized search. Results: Based on histological examination, they were respectively diagnosed as MMGCTs (two cases) and germinoma. Clinical, radiological, pathological characteristics and immunohistochemical profile of the three ICGCTs are presented along with the review of recent literature. Conclusion: ICGCTs are rare tumors affecting males more than females, and at the end of three years follow-up in the present study, treatment morbidity appears to be low with no recurrence observed among surviving patients, indicating that suprasellar and basal ganglia ICGCTs may have a favorable prognosis regardless of histological type. Pineal MMGCTs may have an aggressive course.
Extracranial-intracranial bypass of the bilateral anterior cerebral circulation using a thoracodorsal axis artery-graft
Authors: Jain Abhilash , O'Neill Kevin , Patel Maneesh , Kirkpatrick Niall , Sivathasan Niroshan , Nanchahal Jagdeep
Published: February 2013

Bilateral extracranial-intracranial (EC-IC) bypass-grafting of the cerebral circulation is uncommon. We report a case of anterior cerebral artery EC-IC bypass using the thoracodorsal axis artery-graft. The bifurcation of the thoracodorsal axis allows bypass of both anterior hemispheres, while matching appropriate small-vessel dimensions.
Delayed radiation myelopathy: Differential diagnosis with positron emission tomography/computed tomography examination
Authors: Kadir Tufan , Sarica Feyzi , Ozgur Kardes , Cekinmez Melih , Nur Altinors
Published: February 2013

Myelopathy is a rare but serious complication of radiation therapy (RT). Radiation myelopathy is white matter damage to the spinal cord developed after a certain period of application of ionizing radiation. Factors such as radiation dose and time between applications affect the occurrence as well as the severity of myelopathy. In those patients, positron emission tomography/computed tomography examination has a very important role both in the diagnosis and in the differential diagnosis of lesions. In this case report, the case of progressive paraparesis, developed in a 52-year-old female patient operated with pulmonary mucinous cystadenocarcinoma diagnosis and who received chemotherapy and RT following surgery, has been reported.
Melanotic cyst of L5 spinal root: A case report and review of literature
Authors: Chakravarthy Hariprakash
Published: February 2013

Till date, 85 cases of melanotic schwannoma and 11 cases of spinal root melanoma have been reported in literature. We are reporting a case of a 45-year-old lady who presented with primary low back pain, and magnetic resonance imaging of lumbo-sacral spine showed at left L5-S1 foraminal lesion extending to the para-spinal compartment. Hemi-laminectomy, facetectomy, and excision of the lesion were done. It was primarily a cystic lesion with attachment to the exiting spinal nerve root. Histopathology of the cyst wall showed a fibro-collagenous stroma with no specific cell lining containing melanin pigment suggestive of a melanotic cyst. The patient was completely relieved of the back pain, and had no recurrence over a follow-up period of one and half years. This case is probably the first reported predominantly cystic, pigmented lesion, affecting the spinal root.
Off-line algorithm for calculation of vertical tracer transport in the troposphere due to deep convection
Authors: Belikov D. A. , Maksyutov S. , Krol M. , Fraser A. , Rigby M. , Bian H. , Agusti-Panareda A. , Bergmann D. , Bousquet P. , Cameron-Smith P. , Chipperfield M. P. , Fortems-Cheiney A. , Gloor E. , Haynes K. , Hess P. , Houweling S. , Kawa S. R. , Law R. M. , Loh Z. , Meng L. , Palmer P. I. , Patra P. K. , Prinn R. G. , Saito R. , Wilson C.
Published: February 2013

Abstract. A modified cumulus convection parametrisation scheme is presented. This scheme computes the mass of air transported upward in a cumulus cell using conservation of moisture and a detailed distribution of convective precipitation provided by a reanalysis dataset. The representation of vertical transport within the scheme includes entrainment and detrainment processes in convective updrafts and downdrafts. Output from the proposed parametrisation scheme is employed in the National Institute for Environmental Studies (NIES) global chemical transport model driven by JRA-25/JCDAS reanalysis. The simulated convective precipitation rate and mass fluxes are compared with observations and reanalysis data. A simulation of the short-lived tracer 222Rn is used to further evaluate the performance of the cumulus convection scheme. Simulated distributions of 222Rn are evaluated against observations at the surface and in the free troposphere, and compared with output from models that participated in the TransCom-CH4 Transport Model Intercomparison. From this comparison, we demonstrate that the proposed convective scheme in general is consistent with observed and modeled results.
Peroxyacetyl nitrate (PAN) and peroxyacetic acid (PAA) measurements by iodide chemical ionisation mass spectrometry: first analysis of results in the boreal forest and implications for the measurement of PAN fluxes
Authors: Phillips G. J. , Pouvesle N. , Thieser J. , Schuster G. , Axinte R. , Fischer H. , Williams J. , Lelieveld J. , Crowley J. N.
Published: February 2013

Abstract. We describe measurements of peroxyacetyl nitrate (CH3C(O)O2NO2, PAN) and peroxyacetic acid (CH3C(O)OOH, PAA) in the Boreal forest using iodide chemical ionization mass spectrometry (ICIMS). The measurements were made during the Hyytiälä United Measurement of Photochemistry and Particles – Comprehensive Organic Particle and Environmental Chemistry (HUMPPA-COPEC-2010) measurement intensive. Mixing ratios of PAN and PAA were determined by measuring the acetate ion signal (CH3C(O)O−, m/z = 59) resulting from reaction of CH3C(O)O2 (from the thermal dissociation of PAN) or CH3C(O)OOH with iodide ions using alternatively heated and ambient temperature inlet lines. During some periods of high temperature (~ 30 °C) and low NOx (< 1 ppbv), PAA mixing ratios were similar to, or exceeded those of PAN and thus contributed a significant fraction of the total acetate signal. PAA is thus a potential interference for ICIMS measurements of PAN, and especially eddy covariance flux measurements in environments where the PAA flux is likely to be a significant proportion of the (short timescale) acetate ion variability. Within the range of mixing ratios of NOx measured during HUMPPA-COPEC, the modelled ratio of PAA-to-PAN was found to be sensitive to temperature (through the thermal decomposition rate of PAN) and the HO2 mixing ratio, thus providing some constraint to estimates of photochemical activity and oxidation rates in the Boreal environment.
The melting level stability anomaly in the tropics
Authors: Folkins I.
Published: February 2013

Abstract. On short timescales, the effect of deep convection on the tropical atmosphere is to heat the upper troposphere and cool the lower troposphere. This stratiform temperature response to deep convection gives rise to a local maximum in stability near the melting level. We use temperature measurements from five radiosonde stations in the Western Tropical Pacific, from the Stratospheric Processes and their Role in Climate (SPARC) archive, to examine the response of this mid-tropospheric stability maximum to changes in surface temperature. We find that the height of the stability maximum increases when the surface temperature increases, by an amount roughly equal to the upward displacement of the 0 °C melting level. Although this response was determined using monthly mean temperature anomalies from an 10 yr record (1999–2008), we use model results to show that a similar response should also be expected on longer timescales.
An advanced scheme for wet scavenging and liquid-phase chemistry in a regional online-coupled chemistry transport model
Authors: Knote C. , Brunner D.
Published: February 2013

Abstract. Clouds are reaction chambers for atmospheric trace gases and aerosols, and the associated precipitation is a major sink for atmospheric constituents. The regional chemistry-climate model COSMO-ART has been lacking a description of wet scavenging of gases and aqueous-phase chemistry. In this work we present a coupling of COSMO-ART with a wet scavenging and aqueous-phase chemistry scheme. The coupling is made consistent with the cloud microphysics scheme of the underlying meteorological model COSMO. While the choice of the aqueous-chemistry mechanism is flexible, the effects of a simple sulfur oxidation scheme are shown in the application of the coupled system in this work. We give details explaining the coupling and extensions made, then present results from idealized flow-over-hill experiments in a 2-D model setup and finally results from a full 3-D simulation. Comparison against measurement data shows that the scheme efficiently reduces SO2 trace gas concentrations by 0.3 ppbv (−30%) on average, while leaving O3 and NOx unchanged. PM10 aerosol mass was increased by 10% on average. While total PM2.5 changes only little, chemical composition is improved notably. Overestimations of nitrate aerosols are reduced by typically 0.5–1 μg m−3 (up to −2 μg m−3 in the Po Valley) while sulfate mass is increased by 1–1.5 μg m−3 on average (up to 2.5 μg m−3 in Eastern Europe). The effect of cloud processing of aerosols on its size distribution, i.e. a shift towards larger diameters, is observed. Compared against wet deposition measurements the system tends to underestimate the total wet deposited mass for the simulated case study.
Composite study of aerosol export events from East Asia and North America
Authors: Luan Y. , Jaeglé L.
Published: February 2013

Abstract. We use satellite observations of aerosol optical depth (AOD) from the Moderate Resolution Imaging Spectrometer (MODIS) together with the GEOS-Chem global chemical transport model to contrast export of aerosols from East Asia and North America during 2004–2010. The GEOS-Chem model reproduces the spatial distribution and temporal variations of Asian aerosol outflow generally well, although a low bias (−30%) is found in the model fine mode AOD, particularly during summer. We use the model to identify 244 aerosol pollution export events from E. Asia and 251 export events from N. America over our 7-year study period. When these events are composited by season, we find that the AOD in the outflow is enhanced by 50–100% relative to seasonal mean values. The composite Asian plume splits into one branch going poleward to the Arctic in 3–4 days, with the other crossing the Pacific Ocean in 6–8 days. A fraction of the aerosols is trapped in the subtropical Pacific High during spring and summer. The N. American plume travels to the northeast Atlantic, reaching Europe after 4–5 days. Part of the composite plume turns anticyclonically in the Azores High, where it slowly decays. Both the Asian and N. American export events are favored by a dipole structure in sea-level pressure anomalies, associated with mid-latitude cyclone activity over the respective source regions. This dipole structure during outflow events is a strong feature for all seasons except summer, when convection becomes more important. The observed AOD in the E. Asian outflow exhibits stronger seasonality, with a spring maximum, than the N. American outflow, with a broad spring/summer maximum. The large spring AOD in the Asian outflow is the result of enhanced sulfate and dust aerosol concentrations, but is also due to a larger export efficiency of sulfate and SO2 from the Asian boundary layer relative to the N. American boundary layer. While the N. American sulfate outflow is mostly found in the lower troposphere (1–3 km altitude), the Asian sulfate outflow occurs at higher altitudes (2–6 km). In the Asian outflow 42–59% of the sulfate column is present above 2 km altitude, with only 24–35% in the N. American outflow. We link this to the factor of 2–5 lower precipitation in the warm conveyor belts (WCB) of midlatitude cyclones over E. Asia compared to N. America. This relative lack of precipitation makes Asian WCB very efficient for injecting aerosols in the middle troposphere.
Aircraft observations and model simulations of concentration and particle size distribution in the Eyjafjallajökull volcanic ash cloud
Authors: Dacre H. F. , Grant A. L. M. , Johnson B. T.
Published: February 2013

Abstract. The Eyjafjallajökull volcano in Iceland emitted a cloud of ash into the atmosphere during April and May 2010. Over the UK the ash cloud was observed by the FAAM BAe-146 Atmospheric Research Aircraft which was equipped with in-situ probes measuring the concentration of volcanic ash carried by particles of varying sizes. The UK Met Office Numerical Atmospheric-dispersion Modelling Environment (NAME) has been used to simulate the evolution of the ash cloud emitted by the Eyjafjallajökull volcano during the period 4–18 May 2010. In the NAME simulations the processes controlling the evolution of the concentration and particle size distribution include sedimentation and deposition of particles, horizontal dispersion and vertical wind shear. For travel times between 24 and 72 h, a 1/t relationship describes the evolution of the concentration at the centre of the ash cloud and the particle size distribution remains fairly constant. Although NAME does not represent the effects of microphysical processes, it can capture the observed decrease in concentration with travel time in this period. This suggests that, for this eruption, microphysical processes play a small role in determining the evolution of the distal ash cloud. Quantitative comparison with observations shows that NAME can simulate the observed column-integrated mass if around 4% of the total emitted mass is assumed to be transported as far as the UK by small particles (< 30 μm diameter). NAME can also simulate the observed particle size distribution if a distal particle size distribution that contains a large fraction of < 10 μm diameter particles is used, consistent with the idea that phraetomagmatic volcanoes, such as Eyjafjallajökull, emit very fine particles.
Investigating the influences of SO2 and NH3 levels on isoprene-derived secondary organic aerosol formation using conditional sampling approaches
Authors: Lin Y.-H. , Knipping E. M. , Edgerton E. S. , Shaw S. L. , Surratt J. D.
Published: February 2013

Abstract. Filter-based PM2.5 samples were chemically analyzed to investigate secondary organic aerosol (SOA) formation from isoprene in a rural atmosphere of the southeastern US influenced by both anthropogenic sulfur dioxide (SO2) and ammonia (NH3) emissions. Daytime PM2.5 samples were collected during summer 2010 using conditional sampling approaches based on pre-defined high and low SO2 or NH3 thresholds. Known molecular-level tracers for isoprene SOA formation, including 2-methylglyceric acid, 3-methyltetrahydrofuran-3,4-diols, 2-methyltetrols, C5-alkene triols, dimers, and organosulfate derivatives, were identified and quantified by gas chromatography coupled to electron ionization mass spectrometry (GC/EI-MS) and ultra performance liquid chromatography coupled to electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-Q-TOFMS). Mass concentrations of six isoprene low-NOx SOA tracers contributed to 12–19% of total organic matter (OM) in PM2.5 samples collected during the sampling period, indicating the importance of the hydroxyl radical (OH)-initiated oxidation (so-called photooxidation) of isoprene under low-NOx conditions that leads to SOA formation through reactive uptake of gaseous isoprene epoxydiols (IEPOX) in this region. IEPOX-derived SOA tracers were enhanced under high-SO2 sampling scenarios, suggesting that SO2 oxidation increases aerosol acidity of sulfate aerosols needed for enhancing heterogeneous oxirane ring-opening reactions of IEPOX. No clear associations between isoprene SOA formation and high and low NH3 conditional samples were found. Furthermore, weak correlations between aerosol acidity and mass of IEPOX SOA tracers suggests that IEPOX-derived SOA formation might be modulated by other factors as well in addition to aerosol acidity. Positive correlations between sulfate aerosol loadings and IEPOX-derived SOA tracers for samples collected under all conditions indicates that sulfate aerosol could be a surrogate for surface area in the uptake of IEPOX onto preexisting aerosols.
Organic particle types by single-particle measurements using a time-of-flight aerosol mass spectrometer coupled with a light scattering module
Authors: Liu S. , Russell L. M. , Sueper D. T. , Onasch T. B.
Published: February 2013

Abstract. Chemical and physical properties of individual ambient aerosol particles can vary greatly, so measuring the chemical composition at the single-particle level is essential for understanding atmospheric sources and transformations. Here we describe 46 days of single-particle measurements of atmospheric particles using a time-of-flight aerosol mass spectrometer coupled with a light scattering module (LS-ToF-AMS). The light scattering module optically detects particles larger than 180 nm vacuum aerodynamic diameter (130 nm geometric diameter) before they arrive at the chemical mass spectrometer and then triggers the saving of single-particle mass spectra. 271 641 particles were detected and sampled during 237 h of sampling in single-particle mode. By comparing timing of the predicted chemical ion signals from the light scattering measurement with the measured chemical ion signals by the mass spectrometer for each particle, particle types were classified and their number fractions determined as follows: prompt vaporization (46%), delayed vaporization (6%), and null (48%), where null was operationally defined as less than 6 ions per particle. Prompt and delayed vaporization particles with sufficient chemical information (i.e., more than 40 ions per particle) were clustered based on similarity of organic mass spectra (using k-means algorithm) to result in three major clusters: highly oxidized particles (dominated by m/z 44), relatively less oxidized particles (dominated by m/z 43), and particles associated with fresh urban emissions. Each of the three organic clusters had limited chemical properties of other clusters, suggesting that all of the sampled organic particle types were internally mixed to some degree; however, the internal mixing was never uniform and distinct particle types existed throughout the study. Furthermore, the single-particle mass spectra and time series of these clusters agreed well with mass-based components identified (using factor analysis) from simultaneous ensemble-averaged measurements, supporting the connection between ensemble-based factors and atmospheric particle sources and processes. Measurements in this study illustrate that LS-ToF-AMS provides unique information about organic particle types by number as well as mass.
On the optimal method for evaluating cloud products from passive satellite imagery using CALIPSO-CALIOP data: example investigating the CM SAF CLARA-A1 dataset
Authors: Karlsson K.-G. , Johansson E.
Published: February 2013

Abstract. A method for detailed evaluation of a new satellite-derived global 28-yr cloud and radiation climatology (Climate Monitoring SAF Cloud, Albedo and Radiation dataset from AVHRR data, named CLARA-A1) from polar orbiting NOAA and Metop satellites is presented. The method combines 1 km and 5 km resolution cloud datasets from the CALIPSO-CALIOP cloud lidar for estimating cloud detection limitations and the accuracy of cloud top height estimations. Cloud detection is shown to work efficiently for clouds with optical thicknesses above 0.30 except for at twilight conditions when this value increases to 0.45. Some misclassifications generating erroneous clouds over land surfaces in semi-arid regions in the sub-tropical and tropical regions are revealed. In addition, a substantial fraction of all clouds remains undetected in the Polar regions during the polar winter season due to the lack of or an inverted temperature contrast between Earth surfaces and clouds. Subsequent cloud top height evaluation took into account the derived information about the cloud detection limits. It was shown that this has fundamental importance for the achieved results. An overall bias of −274 m was achieved compared to a bias of −2762 m if no measures were taken to compensate for cloud detection limitations. Despite this improvement it was concluded that high-level clouds still suffer from substantial height underestimations while the opposite is true for low-level (boundary layer) clouds. The validation method and the specifically collected satellite dataset with optimal matching in time and space are suggested for a wider use in the future for evaluation of other cloud retrieval methods based on passive satellite imagery.
Impact of an extremely large magnitude volcanic eruption on the global climate and carbon cycle estimated from ensemble Earth System Model simulations
Authors: Segschneider J. , Beitsch A. , Timmreck C. , Brovkin V. , Ilyina T. , Jungclaus J. , Lorenz S. J. , Six K. D. , Zanchettin D.
Published: February 2013

Abstract. The response of the global climate-carbon cycle system to an extremely large Northern Hemisphere mid-latitude volcanic eruption is investigated using ensemble integrations with the comprehensive Earth System Model MPI-ESM. The model includes dynamical compartments of the atmosphere and ocean and interactive modules of the terrestrial biosphere as well as ocean biogeochemistry. The MPI-ESM was forced with anomalies of aerosol optical depth and effective radius of aerosol particles corresponding to a super eruption of the Yellowstone volcanic system. The model experiment consists of an ensemble of fifteen model integrations that are started at different pre-ENSO states of a control experiment and run for 200 years after the volcanic eruption. The climate response to the volcanic eruption is a maximum global monthly mean surface air temperature cooling of 3.8 K for the ensemble mean and from 3.3 K to 4.3 K for individual ensemble members. Atmospheric pCO2 decreases by a maximum of 5 ppm for the ensemble mean and by 3 ppm to 7 ppm for individual ensemble members approximately 6 years after the eruption. The atmospheric carbon content only very slowly returns to near pre-eruption level at year 200 after the eruption. The ocean takes up carbon shortly after the eruption in response to the cooling, changed wind fields and ice cover. This physics-driven uptake is weakly counteracted by a reduction of the biological export production mainly in the tropical Pacific. The land vegetation pool shows a decrease by 4 GtC due to reduced short-wave radiation that has not been present in a smaller scale eruption. The gain of the soil carbon pool determines the amplitude of the CO2 perturbation and the long-term behaviour of the overall system: an initial gain caused by reduced soil respiration is followed by a rather slow return towards pre-eruption levels. During this phase, the ocean compensates partly for the reduced atmospheric carbon content in response to the land's gain. In summary, we find that the volcanic eruption has long-lasting effects on the carbon cycle: After 200 years, the ocean and the land carbon pools are still different from the pre-eruption state by 3 GtC and 4 GtC, respectively, and the land carbon pools (vegetation and soil) show some long-lasting local anomalies that are only partly visible in the global signal.
High-latitude cooling associated with landscape changes from North American boreal forest fires
Authors: Rogers B. M. , Randerson J. T. , Bonan G. B.
Published: February 2013

Abstract. Fires in the boreal forests of North America are generally stand-replacing, killing the majority of trees and initiating succession that may last over a century. Functional variation during succession can affect local surface energy budgets and, potentially, regional climate. Burn area across Alaska and Canada has increased in the last few decades and is projected to be substantially higher by the end of the 21st century because of a warmer climate with longer growing seasons. Here we simulated changes in forest composition due to altered burn area using a stochastic model of fire occurrence, historical fire data from national inventories, and succession trajectories derived from remote sensing. When coupled to an Earth system model, younger vegetation from increased burning cooled the high-latitude atmosphere, primarily in the winter and spring, with noticeable feedbacks from the ocean and sea ice. Results from multiple scenarios suggest that a doubling of burn area would cool the surface by 0.23 ± 0.09 °C across boreal North America during winter and spring months (December through May). This could provide a negative feedback to winter warming on the order of 3–5% for a doubling, and 14–23% for a quadrupling, of burn area. Maximum cooling occurs in the areas of greatest burning, and between February and April when albedo changes are largest and solar insolation is moderate. Further work is needed to integrate all the climate drivers from boreal forest fires, including aerosols and greenhouse gasses.
Arctic microbial community dynamics influenced by elevated CO2 levels
Authors: Brussaard C. P. D. , Noordeloos A. A. M. , Witte H. , Collenteur M. C. J. , Schulz K. , Ludwig A. , Riebesell U.
Published: February 2013

Abstract. The Arctic Ocean ecosystem is particularly vulnerable to ocean acidification (OA) related alterations due to the relatively high CO2 solubility and low carbonate saturation states of its cold surface waters. Thus far, however, there is only little known about the consequences of OA on the base of the food web. In a mesocosm CO2-enrichment experiment (overall CO2 levels ranged from ~ 180 to 1100 μatm) in Kongsfjorden off Svalbard, we studied the consequences of OA on a natural pelagic microbial community. OA distinctly affected the composition and growth of the Arctic phytoplankton community, i.e. the picoeukaryotic photoautotrophs and to a lesser extent the nanophytoplankton thrived. A shift towards the smallest phytoplankton as a result of OA will have direct consequences for the structure and functioning of the pelagic food web and thus for the biogeochemical cycles. Besides being grazed, the dominant pico- and nanophytoplankton groups were found prone to viral lysis, thereby shunting the carbon accumulation in living organisms into the dissolved pools of organic carbon and subsequently affecting the efficiency of the biological pump in these Arctic waters.
The role of microorganisms and plants at different stages of ecosystem development for soil formation
Authors: Schulz S. , Brankatschk R. , Dümig A. , Kögel-Knabner I. , Schloter M. , Zeyer J.
Published: February 2013

Abstract. Soil formation is the result of a complex network of biological as well as chemical and physical processes. Mainly the role of soil microbes is of high interest in this respect, as they are responsible for most transformations and drive the development of stable and labile carbon and nutrient pools in soil, which facilitate the basis for the subsequent establishment of plant communities. Glacier forefields, which provide a chronosequence of soils of different age due to the continuous retreat of the ice layer as a consequence of the increasing annual temperature since the last centuries, are a nice play ground to study the interaction of bacteria, fungi and archaea with their abiotic environment at different stages of soil formation. In this review we give insights into the role of microbes for soil development on the basis of investigations which have been performed at the Damma glacier in Switzerland in the frame of two international network projects Big Link (http://www.cces.ethz.ch/projects/clench/BigLink/) and DFG SFB/TRR 38 (http://www.tu-cottbus.de/ecosystem/). The review focusses on the microbiology of three major steps of soil formation including weathering of the parental material, the development of basic nutrient cycles, the formation of soil crusts and biofilms as initial microbial network structures and the occurrence of plants respectively the setup of plant communities.