Atmospheric predictability revisited

This article examines the potential to improve numerical weather prediction (NWP) by estimating upper and lower bounds on predictability by re-visiting the original study of Lorenz (1982) but applied to the most recent version of the European Centre for Medium Range Weather Forecasts (ECMWF) forecast system, for both the deterministic and ensemble prediction systems (EPS). These bounds are contrasted with an older version of the same NWP system to see how they have changed with improvements to the NWP system. The computations were performed for the earlier seasons of DJF 1985/1986 and JJA 1986 and the later seasons of DJF 2010/2011 and JJA 2011 using the 500-hPa geopotential height field. Results indicate that for this field, we may be approaching the limit of deterministic forecasting so that further improvements might only be obtained by improving the initial state. The results also show that predictability calculations with earlier versions of the model may overestimate potential forecast skill, which may be due to insufficient internal variability in the model and because recent versions of the model are more realistic in representing the true atmospheric evolution. The same methodology is applied to the EPS to calculate upper and lower bounds of predictability of the ensemble mean forecast in order to explore how ensemble forecasting could extend the limits of the deterministic forecast. The results show that there is a large potential to improve the ensemble predictions, but for the increased predictability of the ensemble mean, there will be a trade-off in information as the forecasts will become increasingly smoothed with time. From around the 10-d forecast time, the ensemble mean begins to converge towards climatology. Until this point, the ensemble mean is able to predict the main features of the large-scale flow accurately and with high consistency from one forecast cycle to the next. By the 15-d forecast time, the ensemble mean has lost information with the anomaly of the flow strongly smoothed out. In contrast, the control forecast is much less consistent from run to run, but provides more detailed (unsmoothed) but less useful information.

Insights into the dynamics and sources of atmospheric lead and particulate matter in Sao Paulo, Brazil, from high temporal resolution sampling

We present the first results of a study investigating the processes that control concentrations and sources of Pb and particulate matter in the atmosphere of Sao Paulo City Brazil Aerosols were collected with high temporal resolution (3 hours) during a four-day period in July 2005 The highest Pb concentrations measured coincided with large fireworks during celebration events and associated to high traffic occurrence Our high-resolution data highlights the impact that a singular transient event can have on air quality even in a megacity Under meteorological conditions non-conducive to pollutant dispersion Pb and particulate matter concentrations accumulated during the night leading to the highest concentrations in aerosols collected early in the morning of the following day The stable isotopes of Pb suggest that emissions from traffic remain an Important source of Pb in Sao Paulo City due to the large traffic fleet despite low Pb concentrations in fuels (C) 2010 Elsevier BV All rights reserved

Determinação de Cd, Pb e Cu em particulados atmosféricos da região de Presidente Prudente por análise voltamétrica utilizando eletrodo de mercúrio

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Characterization of atmospheric aerosols in the city of So Paulo, Brazil: comparisons between polluted and unpolluted periods

The objective of this study was to determine the size and composition of atmospheric aerosols in the downtown area of the city of So Paulo, Brazil, for a polluted and an unpolluted period. Aerosols were sampled with a portable air sampler (PAS), Micro-Orifice Uniform Deposit Impactor (MOUDI), and Scanning Mobility Particle Sizer. At the study site, air quality is poor, especially during the winter, high concentrations of pollutants being emitted primarily by the light- and heavy-duty vehicle fleet. We analyzed mass, black carbon (BC), Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sn, Zr, and Pb. During the polluted period, diurnal PM(10) was higher than nocturnal PM(10), whereas the inverse was true during the unpolluted period. The FPM was rich in BC, S, and Pb, whereas CPM was rich in Al, Si, Ca, Ti, and Fe. Mass balance was performed by category: ammonium sulfate, sodium chloride, crustal material, BC, and other. The PAS-determined FPM was mainly BC. The MOUDI-determined FPM crustal material explained more mass than did ammonium sulfate and BC during the polluted period, whereas ammonium sulfate had the largest mass during the unpolluted period. Crustal material was the major CPM component, followed by ammonium sulfate and BC. During the unpolluted period, FPM concentrations were lower, whereas those of ammonium sulfate were relatively higher, especially at night, and particle number was inversely proportional to particle size. Aerosol growth was more intense during the polluted period.

G'day Gondwana - the final accretion of a supercontinent: U-Pb ages from the post-orogenic Sao Vicente Granite, northern Paraguay Belt, Brazil

The Paraguay Belt in central South America is part of a larger chain of orogenic belts, including the Araguaia Belt to the northeast and potentially the Pampean Belt to the south, which are believed to mark the suture zone of the Clymene Ocean - interpreted amongst the youngest of the Gondwana amalgamation orogens. The post-orogenic Sao Vicente Granite crops out in the northern Paraguay Belt and cuts the basal unit of the deformed and metamorphosed Cuiaba Group. The age of this granite therefore provides a long sort after minimum age for orogenesis within the belt. Dating crystallisation of this important intrusion is challenging due to the presence of considerable common-Pb. However, based on LA-ICPMS dating of more than 100 zircons from three separate samples we interpret a robust crystallisation age for the Sao Vicente batholith at 518 +/- 4 Ma. This age constrains the termination of deformation within the Paraguay Belt and the final accretion of the supercontinent Gondwana. (C) 2011 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

Origin and variability of PM10 and atmospheric radiotracers at the WMO-GAW station of Mt. Cimone (1998-2011) and in the central Po Valley

Particulate matter is one of the main atmospheric pollutants, with a great chemical-environmental relevance. Improving knowledge of the sources of particulate matter and of their apportionment is needed to handle and fulfill the legislation regarding this pollutant, to support further development of air policy as well as air pollution management. Various instruments have been used to understand the sources of particulate matter and atmospheric radiotracers at the site of Mt. Cimone (44.18° N, 10.7° E, 2165 m asl), hosting a global WMO-GAW station. Thanks to its characteristics, this location is suitable investigate the regional and long-range transport of polluted air masses on the background Southern-Europe free-troposphere. In particular, PM10 data sampled at the station in the period 1998-2011 were analyzed in the framework of the main meteorological and territorial features. A receptor model based on back trajectories was applied to study the source regions of particulate matter. Simultaneous measurements of atmospheric radionuclides Pb-210 and Be-7 acquired together with PM10 have also been analysed to acquire a better understanding of vertical and horizontal transports able to affect atmospheric composition. Seasonal variations of atmospheric radiotracers have been studied both analysing the long-term time series acquired at the measurement site as well as by means of a state-of-the-art global 3-D chemistry and transport model. Advection patterns characterizing the circulation at the site have been identified by means of clusters of back-trajectories. Finally, the results of a source apportionment study of particulate matter carried on in a midsize town of the Po Valley (actually recognised as one of the most polluted European regions) are reported. An approach exploiting different techniques, and in particular different kinds of models, successfully achieved a characterization of the processes/sources of particulate matter at the two sites, and of atmospheric radiotracers at the site of Mt. Cimone.

210Pb dating of the Miaoergou ice core from the eastern Tien Shan, China

In 2005, two ice cores with lengths of 58.7 and 57.6 m respectively to bedrock were recovered from the Miaoergou flat-topped glacier (43 degrees 03 ' 19 '' N, 94 degrees 19 ' 21 '' E; 4512 m a.s.l.), eastern Tien Shan. Pb-210 dating of one of the ice cores (57.6 m) was performed, and an age of AD 1851 +/- 6 at a depth of 35.2 m w.e. was determined. For the period AD 1851-2005, a mean annual net accumulation of 229 +/- 7 mm w.e. a(-1) was calculated. At the nearby oasis city of Hami (similar to 80 km from the Miaoergou flat-topped glacier) the annual precipitation rate is 38 mm w.e. a(-1), hence glacial meltwater is a major water supply for local residents. The surface activity concentration of Pb-210(ex) was found to be similar to 400 mBq kg(-1), which is higher than observed at other continental sites such as Belukha, Russia, and Tsambagarav, Mongolia, which have surface activity concentrations of 280 mBq kg(-1). The Pb-210 dating agrees well with the chronological sequence deduced from the annual-layer counting resulting from the seasonalities of delta O-18 and trace metals for the period AD 1953-2005, and beta-activity horizons resulting from atmospheric nuclear testing during the period AD 1962-63. We conclude that Pb-210 analysis is a suitable method for obtaining a continuous dating of the Miaoergou ice core for similar to 160 years, which can also be applied to other ice cores recovered from the mountains of western China.

High-resolution AMS (super 14) C dating of post-bomb peat archives of atmospheric pollutants.

Peat deposits in Greenland and Denmark were investigated to show that high-resolution dating of these archives of atmospheric deposition can be provided for the last 50 years by radiocarbon dating using the atmospheric bomb pulse. (super 14) C was determined in macrofossils from sequential one cm slices using accelerator mass spectrometry (AMS). Values were calibrated with a general-purpose curve derived from annually averaged atmospheric (super 14) CO (sub 2) values in the northernmost northern hemisphere (NNH, 30 degrees -90 degrees N). We present a through review of (super 14) C bomb-pulse data from the NNH including our own measurements made in tree rings and seeds from Arizona as well as other previously published data. We show that our general-purpose calibration curve is valid for the whole NNH producing accurate dates within 1-2 years. In consequence, (super 14) C AMS can precisely date individual points in recent peat deposits within the range of the bomb-pulse (from the mid-1950s on). Comparing the (super 14) C AMS results with the customary dating method for recent peat profiles by (super 210) Pb, we show that the use of (super 137) Cs to validate and correct (super 210) Pb dates proves to be more problematic than previously supposed. As a unique example of our technique, we show how this chronometer can be applied to identify temporal changes in Hg concentrations from Danish and Greenland peat cores.

Re-OS and Pb isotope ratios of sediments from Saanich Inlet, Western Canada

Re-Os and Pb-Pb isotopic analysis of reduced varved sediments cored in the deeper basin of Saanich Inlet (B.C.) are presented. From core top to 61 cm down-core, spanning approximately the last 100 yrs of sedimentation, 187Os/188Os ratio and Os concentration respectively increase from ~0.8 to ~0.9 and from 55 to 60 ppt, whereas Re concentration decreases from 3600 to 2600 ppt. Re correlates with Corg (R2=0.6) throughout the entire section, whereas Os follows Re and Corg trends deeper down-core, suggesting a decoupling of a Re- and Os-geochemistry during burial and/or very early diagenesis. No systematic compositional differences are observed between seasonal laminae. 204Pb-normalized lead isotope ratios increase from sediment surface down to 7 cm down-core, then decrease steadily to pre-industrial levels at ~50 cm down-core. This pattern illustrates the contamination from leaded gasoline until the recent past. The measured Pb isotopic ratios point primarily toward gasoline related atmospheric lead from the USA. The osmium isotopic values measured are significantly lower than those of modern seawater-Os. In comparison with other anoxic environments, the osmium content of Saanich Inlet sediments is low, and its Os isotopic composition suggests significant inputs from unradiogenic sources (detrital and/or dissolved). Ultramafic lithologies in the watershed of the Fraser River are suspected to contribute to sedimentary inputs as well as to the input of dissolved unradiogenic osmium in the water of Saanich Inlet. The presence of some unradiogenic Os from anthropogenic contamination cannot be discounted near the core top, but since deeper, pre-anthropogenic levels also yielded unradiogenic Os results, one is led to conclude that the overall low 187Os/188Os ratios result from natural geochemical processes. Thus, the bulk sediment of Saanich Inlet does not appear to record 187Os/188Os composition of the marine end-member of the only slightly below normal salinity, fjord water. The low seawater-derived Os content of the sediment, coupled with unradiogenic Os inputs from local sources, explains the overall low isotopic values observed. As a consequence, such near-shore anoxic sediments are unlikely to record changes in the past ocean Os isotopic composition.

(Table A1) Isotopic ratios of Sr, Nd, and Pb for sediments in ODP Leg 138 sites

The provenance of eolian dust supplied to deep-sea sediments has the potential to offer insights into changes in past atmospheric circulation. Specifically, measuring temporal changes in dust provenance can shed light on changes in the mean position of the Intertropical Convergence Zone (ITCZ), a region acting as a barrier separating wind-blown material derived from northern versus southern hemisphere sources. Here we have analyzed Nd, Sr, and Pb isotope ratios in the operationally-defined detrital component extracted from deep-sea sediments in the eastern equatorial Pacific (EEP) along a meridional transect at 110°W from 3°S to 7°N (ODP Leg 138, sites 848-853). Sr isotope results show that barite Sr has a significant influence on 87Sr/86Sr isotope ratios of samples in the upwelling zone of the EEP. However, sites located >3° or more away from the equator (sites 852 and 853) are believed to not be affected by barite Sr and provide useful detrital Sr signals. 208Pb/206Pb and 207Pb/206Pb ratios in all cores fall into the Pb-isotope space of five potential dust sources (Asia, North and Central/South America, Sahara, and Australia), with no distinct isotopic fingerprinting of the dominant source(s). epsilon-Nd values were most valuable for discerning detrital source provenance, and their values at all sites, ranging from ~5.46 to ~3.25, were more unradiogenic for sediments deposited during the last glacial than for those deposited during the Holocene. There are distinct latitudinal trends in the epsilon-Nd values, with more radiogenic values further south and less radiogenic values further north, excluding site 848. This distinction holds true for both Holocene and last glacial periods. For the most southerly site, 848, we invoke, for the first time, a distinct southern hemisphere Australian source as being responsible for the unradiogenic Nd isotope ratios. Both average last glacial and Holocene epsilon-Nd values show similar sharp gradients along the transect between 5.29°N and 2.77°N, suggesting little movement of the glacial ITCZ in the EEP. However, during the deglacial, this gradient is stronger and shifted further north between 5.29°N and 7.21°N, suggesting a more northerly, possibly stronger, deglacial ITCZ.

Urban trees and atmospheric pollutants in big cities: Effects in Madrid

Una investigación sobre la mejora de la contaminación del aire (CA) por medio de arbolado urbano se realizó en Madrid, una ciudad con casi 4 M de habitantes, 2,8 M de vehículos y casi 3 M de árboles de mantenimiento público. La mayoría de los árboles estaban en dos bosques periurbanos. Los 650.000 restantes era pies de alineación y parques. Los taxones estudiados fueron Platanus orientalis (97.205 árboles), Ulmus sp. (70.557), Pinus pinea (49.038), Aesculus hippocastanum (22.266), Cedrus sp. (13.678) y Quercus ilex (1.650), de calles y parques. Muestras foliares se analizaron en diferentes épocas del año, así como datos de contaminación por PM10 de 28 estaciones de medición de la contaminación durante 30 años, y también la intensidad del tráfico (IMD) en 2.660 calles. La acumulación de metales pesados (MP) sobre hojas y dentro de estas se estimó en relación con la CA y del suelo y la IMD del tráfico. La concentración media de Ba, Cd, Cr, Cu, Mn, Ni, Pb y Zn en suelo (materia seca) alcanzó: 489,5, 0,7, 49,4, 60,9, 460,9, 12,8, 155,9 y 190,3 mg kg-1 respectivamente. Los árboles urbanos, particularmente coníferas (debido a la mayor CA en invierno) contribuyen significativamente a mejorar la CA sobre todo en calles con alta IMD. La capacidad de las seis sp. para capturar partículas de polvo en su superficies foliares está relacionada con la IMD del tráfico y se estimó en 16,8 kg/año de MP tóxicos. Pb y Zn resultaron ser buenos marcadores antrópicos en la ciudad en relación con el tráfico, que fue la principal fuente de contaminación en los árboles y suelos de Madrid. Las especies de árboles variaron en función de su capacidad para capturar partículas (dependiendo de las propiedades de sus superficies foliares) y acumular los MP absorbidos de los suelos. Las concentraciones foliares de Pb y Zn estuvieron por encima de los límites establecidos en diferentes sitios de la ciudad. La microlocalización de Zn mediante microscópico mostró la translocación al xilema y floema. Se detectaron puntos de contaminación puntual de Cu and Cr en antiguos polígonos industriales y la distribución espacial de los MP en los suelos de Madrid mostró que en incluso en zonas interiores del El Retiro había ciertos niveles elevados de [Pb] en suelo, tal vez por el emplazamiento la Real Fábrica de Porcelana en la misma zona hace 200 años. Distintas áreas del centro de la ciudad también alcanzaron niveles altos de [Pb] en suelo. Según los resultados, el empleo de una combinación de Pinus pinea con un estrato intermedio de Ulmus sp. y Cedrus sp. puede ser la mejor recomendación como filtro verde eficiente. El efecto del ozono (O3) sobre el arbolado en Madrid fue también objeto de este estudio. A pesar de la reducción de precursores aplicada en muchos países industrializados, O3 sigue siendo la principal causa de CA en el hemisferio norte, con el aumento de [O3] de fondo. Las mayores [O3] se alcanzaron en regiones mediterráneas, donde el efecto sobre la vegetación natural es compensado por el xeromorfismo y la baja conductancia estomática en respuesta los episodios de sequía estival característicos de este clima. Durante una campaña de monitoreo, se identificaron daños abióticos en hojas de encina parecidos a los de O3 que estaban plantadas en una franja de césped con riego del centro de Madrid. Dada la poca evidencia disponible de los síntomas de O3 en frondosas perennifolias, se hizo un estudio que trató de 1) confirman el diagnóstico de daño de O3, 2) investigar el grado de los síntomas en encinas y 3) analizar los factores ambientales que contribuyeron a los daños por O3, en particular en lo relacionado con el riego. Se analizaron los marcadores macro y micromorfológicos de estrés por O3, utilizando las mencionadas encinas a modo de parcela experimental. Los síntomas consistieron en punteado intercostal del haz, que aumentó con la edad. Además de un punteado subyacente, donde las células superiores del mesófilo mostraron reacciones características de daños por O3. Las células próximas a las zonas dañadas, presentaron marcadores adicionales de estrés oxidativo. Estos marcadores morfológicos y micromorfológicos de estrés por O3 fueron similares a otras frondosas caducifolias con daños por O3. Sin embargo, en nuestro caso el punteado fue evidente con AOT40 de 21 ppm•h, asociada a riego. Análisis posteriores mostraron que los árboles con riego aumentaron su conductancia estomática, con aumento de senescencia, manteniéndose sin cambios sus características xeromórficas foliares. Estos hallazgos ponen de relieve el papel primordial de la disponibilidad de agua frente a las características xeromórficas a la hora de manifestarse los síntomas en las células por daños de O3 en encina. ABSTRACT Research about air pollution mitigation by urban trees was conducted in Madrid (Spain), a southern European city with almost 4 M inhabitants, 2.8 M daily vehicles and 3 M trees under public maintenance. Most trees were located in two urban forests, while 650'000 trees along urban streets and in parks. The urban taxa included Platanus orientalis (97'205 trees), Ulmus sp. (70’557), Pinus pinea (49'038), Aesculus hippocastanum (22’266), Cedrus sp. (13'678 and Quercus ilex (1'650) along streets and parks. Leave samples were analysed sequentially in different seasons, PM10 data from 28 air monitoring stations during 30 years and traffic density estimated from 2’660 streets. Heavy metal (HM) accumulation on the leaf surface and within leaves was estimated per tree related to air and soil pollution, and traffic intensity. Mean concentration of Ba, Cd, Cr, Cu, Mn, Ni, Pb and Zn in topsoil samples (dry mass) amounted in Madrid: 489.5, 0.7, 49.4, 60.9, 460.9, 12.8, 155.9 and 190.3 mg kg-1 respectively. Urban trees, particularly conifers (due to higher pollution in winter) contributed significantly to alleviate air pollution especially near to high ADT roads. The capacity of the six urban street trees species to capture air-born dust on the foliage surface as related to traffic intensity was estimated to 16.8 kg of noxious metals from exhausts per year. Pb and Zn pointed to be tracers of anthropic activity in the city with vehicle traffic as the main source of diffuse pollution on trees and soils. Tree species differed by their capacity to capture air-borne dust (by different leaf surface properties) and to allocate HM from soils. Pb and Zn concentrations in the foliage were above limits in different urban sites and microscopic Zn revelation showed translocation in xylem and phloem tissue. Punctual contamination in soils by Cu and Cr was identified in former industrial areas and spatial trace element mapping showed for central Retiro Park certain high values of [Pb] in soils even related to a Royal pottery 200 years ago. Different areas in the city centre also reached high levels [Pb] in soils. According to the results, a combination of Pinus pinea with understorey Ulmus sp. and Cedrus sp. layers can be recommended for the best air filter efficiency. The effects of ozone (O3) on trees in different areas of Madrid were also part of this study. Despite abatement programs of precursors implemented in many industrialized countries, ozone remained the main air pollutant throughout the northern hemisphere with background [O3] increasing. Some of the highest ozone concentrations were measured in regions with a Mediterranean climate but the effect on the natural vegetation is alleviated by low stomatal uptake and frequent leaf xeromorphy in response to summer drought episodes characteristic of this climate. During a bioindication survey, abiotic O3-like injury was identified in foliage. Trees were growing on an irrigated lawn strip in the centre of Madrid. Given the little structural evidence available for O3 symptoms in broadleaved evergreen species, a study was undertaken in 2007 with the following objectives 1) confirm the diagnosis, 2) investigate the extent of symptoms in holm oaks growing in Madrid and 3) analyse the environmental factors contributing to O3 injury, particularly, the site water supply. Therefore, macro- and micromorphological markers of O3 stress were analysed, using the aforementioned lawn strip as an intensive study site. Symptoms consisted of adaxial and intercostal stippling increasing with leaf age. Underlying stippling, cells in the upper mesophyll showed HR-like reactions typical of ozone stress. The surrounding cells showed further oxidative stress markers. These morphological and micromorphological markers of ozone stress were similar to those recorded in deciduous broadleaved species. However, stippling became obvious already at an AOT40 of 21 ppm•h and was primarily found at irrigated sites. Subsequent analyses showed that irrigated trees had their stomatal conductance increased and leaf life-span reduced whereas their leaf xeromorphy remained unchanged. These findings suggest a central role of water availability versus leaf xeromorphy for ozone symptom expression by cell injury in holm oak.

Integrated Pb- and S-isotope investigation of sulphide minerals from the early Archaean of southwest Greenland

We present high-spatial resolution secondary ion mass spectrometry (SIMS) measurements of Pb and S isotopes in sulphides from early Archaean samples at two localities in southwest Greenland. Secondary pyrite from a 3.71 Ga sample of magnetite-quartz banded iron formation in the Isua Greenstone Belt, which has previously yielded unradiogenic Pb consistent with its ancient origin, contains sulphur with a mass independently fractionated (MIF) isotope signature (Delta(33)S =+3.3 parts per thousand). This reflects the secondary mineralization of remobilized sedimentary S carrying a component modified by photochemical reactions in the early Archaean atmosphere. It further represents one of the most extreme positive excursions so far known from the early Archaean rock record. Sulphides from a quartz-pyroxene rock and an ultramafic boudin from the island of Akilia, in the Godth (a) over circle bsfjord, have heterogeneous and generally radiogenic Pb isotopic compositions that we interpret to represent partial re-equilibration of Pb between the sulphides and whole rocks during tectonothermal events at 3.6, 2.7 and 1.6 Ga. Both these samples have Delta(33)S=0 (within analytical error) and therefore show no evidence for MIF sulphur. These data are consistent with previous interpretations that the rock cannot be proven to have a sedimentary origin. Our study illustrates that SIMS S-isotope measurements in ancient rocks can be used to elucidate early atmospheric parameters because of the ability to obtain combined S and Pb-isotope data, but caution must be applied when using such data to infer protolith. When information from geological context, petrography and chronology (i.e. by Pb isotopes) is combined and fully evaluated, Delta(33)S signatures from sulphides and their geological significance can be interpreted with a higher degree of confidence. (c) 2005 Elsevier B.V All rights reserved.

Characterisation of atmospheric single particles in industrial and regional background environments using aerosol time of flight mass spectrometry

The composition of atmospheric particles is an important factor in determining their impact on climate and health. In this study, an aerosol time-of-flight mass spectrometer (ATOFMS) was used to measure the chemical composition of ambient single particles at two contrasting locations – an industrial site in Dunkirk, France and a regional background site in Corsica. The ATOFMS data were combined with meteorological information and other particle measurements to determine the various sources of the particles observed at the sites. The particle classes detected in Dunkirk included carbonaceous species from fossil fuel combustion and biomass burning, metal-containing types from local industries and seasalt. Highest particle number concentrations and mass concentrations of PM2.5, black carbon, organics, nitrate, ammonium and several metallic species (Fe, Mn, Pb, Zn) were found during periods heavily influenced by local industry. Particles from a ferromanganese alloy manufacturing facility were identified by comparing ambient ATOFMS data with single particle mass spectra from industrial chimney filters and ores. Particles from a steelworks were identified based on comparison of the ambient data with previous studies. Based on these comparisons, the steelworks was identified as the dominant emitter of Fe-rich particles, while the ferromanganese alloy facility emitted Mn-rich particles. In Corsica, regional transport of carbonaceous particles from biomass burning and fossil fuel combustion was identified as the major source of particles in the Mediterranean background aerosol. Throughout the campaign the site was influenced by air masses altering the composition of particles detected. During North Atlantic air masses the site was heavily influenced by fresh sea salt. Regional stagnation was the most common type of air mass regime throughout the campaign and resulted in the accumulation of carbonaceous particles during certain periods. Mass concentrations were estimated for ATOFMS particle classes, and good agreement was found between the major carbonaceous classes and other quantitative measurements. Overall the results of this work serve to highlight the excellent ability of the ATOFMS technique in providing source-specific composition and mixing state information on atmospheric particles at high time resolution.

Isotope record of Nd-Sr-Pb in deep sea sediments from the Pacific (Table 2)

Pelagic clay of the east-central Pacific province is shown to be a mixture of three primary detrital components, reflecting continental source areas in Asia, North America, and Central and South America. Relative contributions from each source area are a function of geography, and this distribution appears to have remained constant over the past five million years, despite changing flux rates. A Q-mode factor analysis of downcore records for Pb, Sr, and Nd isotopes identified three factors that account for 98% of the total variance. These factors represent the radiogenic isotopic signatures of 1) late Cenozoic Asian dust, which dominates in the central North Pacific; 2) North American continental hemipelagic/eolian sources, restricted mainly to the easternmost North Pacific at ~30 °N latitude; and 3) Central and South American sources, restricted to areas east of ~100 °W longitude. South of the Intertropical Convergence Zone (~6 °N), the Asian dust signature diminishes abruptly. We conclude that late Cenozoic Asian dust sources can be isotopically differentiated downcore from both North American and South and Central American sources in the eastcentral Pacific. This approach has a utility for identifying changes in long-term Cenozoic atmospheric circulation patterns.