Assessing the Impact of Advected African Dust on Air Quality and Health in the Eastern United States

Large quantities of African dust are carried into the southeastern United States each summer with concentrations typically in the range of 10 to 100?µg m^?3. Because approximately one-third to one-half of the dust mass is in the size range under 2.5?µm diameter, the advection of African dust has implications for the EPA's newly implemented standard for PM_2.5 particulate matter and for the assessment of human health effects. It will be difficult to assess the impact of African dust events on air quality because they occur during the summer (maximum in July) when photochemical pollution events are frequent and intense in the eastern United States. Indeed, the presence of dust could affect the evolution of photochemical dust events. In order to assess the role of African dust in air quality in the United States, it will be necessary to develop a set of diagnostic indicators; it appears that dust mineralogy and elemental composition might be useful for this purpose. Various satellite products can be used to characterize the spatial coverage of dust events and, when coupled with meteorological tools, to predict impact regions.     

CO2 emission from mineral soils following land‐cover change in Brazil

This paper presents a first approximation of net CO₂ fluxes from mineral soil due to land use, land‐use changes and forestry (LULUCF) activities in Brazil for the periods 1970–90 and 1975–95. The methodology employed is an adaptation of the approach proposed by the IPCC in ‘Revised 1996 guidelines for national greenhouse gas inventories’, which is based on the variations in soil C stocks as a function of changes in land‐use activities. The calculation was done separately for each Brazilian state and subsequently summarized for all of Brazil. The annual fluxes for Brazil indicate a net emission of CO₂ to the atmosphere, which decreased from 93.3 Tg CO₂ for the period 1970–90 to 46.4 Tg CO₂ for the period 1975–95. This corresponded to yearly net emission rates of 11.0 g CO₂ m^?2 year^?1 for the 1970–90 period and 5.5 g CO₂ m^?2 year^?1 for the 1975–95 period. Within each administrative region, considerable differences in the yearly emission rates between the states could be observed. Several sources of uncertainties could be identified. The most important uncertainties were linked to the impact factor values, which represent changes in native C stock associated with conversion of the native vegetation to agricultural use.     

Atmospheric element deposit on tree barks: The opposite effects of rain and transpiration

The elemental composition of the deposit formed on the bark of ash-trees was studied over several months on stems ranging from 3 months to 10 years. For this purpose (1) the total elemental composition of the deposit, (2) the structure and composition of the solid particles and (3) the deposit dry weight per dm² were studied. Concurrently the part of this superficial deposit washed out by rain during 3.5 months was sampled at each rain event and its elemental composition analyzed. This study shows that the deposit was submitted to an intense turnover, with an average leaching-out flux reaching approximately 27 mg dm⁻² month⁻¹ and a very low increase of the deposit weight per dm² during the first five years and almost null afterwards. The origin of this superficial deposit was investigated. The main part (78 ± 10%) was organic matter originating from the atmospheric deposition or from the tree. The inorganic content originated partly from the atmosphere, with geogenic and anthropogenic particles, and also from the tree, in which it was demonstrated by scanning electron microscopy - energy dispersive X-ray that a non-negligible part was obtained from bark transpiration, inducing a superficial deposit, mainly of Ca or K in the area surrounding the lenticels. All those results demonstrate that this bark superficial deposit is a complex matrix which must not be considered as a simple cumulative archive but which seems to be the source of interesting information targeting mostly recent atmospheric pollution pressures, when compared to the bulk of suber integrated particles.     

Denitrification triggered by nitrogen addition in Sphagnum magellanicum peat

Ombrotrophic (rain-fed) Sphagnum-mires do not significantly contribute to gaseous nitrogen (N) emissions to the atmosphere. However, increasing levels of N deposition reduce Sphagnum growth and moss cover. As a consequence, higher amounts of mineral N reach the underlying peat beneath the moss layer. The aim of our work was to determine the effects of supplementary N inputs to peat beneath Sphagnum magellanicum carpets. Peat cores were incubated in controlled laboratory conditions of temperature and humidity, and the impact of increasing N inputs was evaluated on denitrification rates, basal respiration and methane emissions. Rates of denitrification were quickly stimulated by addition of 1?g?N?m^?2 but rates were not significantly elevated in the short-term (9?days) by further additions of up to 10?g?N?m^?2. Over a longer term period (up to 45?days), denitrification rates followed an exponential (10?g?N?m^?2 addition) or a gamma (1?g?N?m^?2) function. Findings from this study support the hypothesis that mineral-N addition in atmospheric deposition will have a negative effect on peat biogeochemistry, by modifying its N sink capacity via denitrification leading to a potential increase in N₂O emissions.     

Seasonal denitrification in flooded and exposed sediments from the Amazon floodplain at Lago Camaleão

Denitrification processes were measured by the acetylene-blockage technique under changing flood conditions along the aquatic/terrestrial transition zone on the Amazon floodplain at Lago Camaleão, near Manaus, Brazil. In flooded sediments, denitrification was recorded after the amendment with NO ₃ ^– (100 mol liter^–1) throughout the whole study period from August 1992 to February 1993. It ranged from 192.3 to 640.7 mol N m^–2 h^–1 in the 0- to 5-cm sediment layer. Without substrate amendment, denitrification was detected only during low water in November and December 1992, when it occurred at a rate of up to 12.2 mol N m^–2 h^–1 Higher rates of denitrification at an average rate of 73.3 mol N m^–2 h^–1 were measured in sediments from the shallow lake basin that were exposed to air at low water. N₂O evolution was never detected in flooded sediments, but in exposed sediments, it was detected at an average rate of 28.3 mol N m^–2 h^–1 during the low-water period. The results indicate that under natural conditions there is denitrification and hence a loss in nitrogen from the Amazon floodplain to the atmosphere. Rates of denitrification in flooded sediments were one to two orders of magnitude smaller than in temperate regions. However, the nitrogen removal of exposed sediments exceeded that of undisturbed wetland soils of temperate regions, indicating a considerable impact of the flood pulse on the gaseous turnover of nitrogen in the Amazon floodplain.     

Mass Mortality of Coral Reef Ascidians Following the 1997/1998 El Niño Event

In April/May each year from 1995 to 2000, ascidians were sampled randomly with 35 1m² quadrats from three different reef habitats (intertidal reef tops, coastal reef walls and shallow-bank reefs) at four replicate localities (Praia do Forte, Itacimirim, Guarajuba and Abai) in northern Bahia (Brazil). As the sampling period included the 1997/1998 El Niño event, the most severe on record, for the first time these results allow a quantitative assessment of the impact of this major environmental stressor on the biodiversity of associated coral reef ascidians. Across all reef habitats, 22 ascidian species were recorded from three different orders (Aplousobranchia, Phlebobranchia and Stolidobranchia). After El Niño, all species showed significantly altered densities (ANOVA, F=602.90, p<0.0001); many species were absent from the reefs within 2 years of the El Niño period, but densities of Lissoclinum perforatum (all reefs) and Echinoclinum verrilli (subtidal reefs) increased significantly from 1998 onwards. Univariate and multivariate analyses confirmed that significant changes in assemblage composition had occurred. BIOENV analysis identified turbidity, mean temperature and cloud cover as the main factors best explaining these assemblage changes. Our results suggest that although the 1997/1998 El Niño had a differential effect on the species contributing to the ascidian assemblage of Brazilian coral reefs, most species disappeared and those remaining are likely to enhance reef degradation through their bioeroding activities.     

The impact of forest area fragmentation on ant population

The paper presents an analysis of the impact of some morphological and ecological factors on the spatial distribution of 19 ant species populating fragmented forest areas within an urban territory. Twofold reduction of the species composition in small forested fragments with an area less than 5000 m² was shown. The highest density of ant anthills against the background of a high degree of species diversity similar to that in the slightly fragmented territories was found in median fragments with an area varying from 10000 to 250000 m². The influence of anthill construction diversity and size of workers on the resistance of species to area reduction was revealed. Species with 3–5 mm long workers that dwell in nests with and without epiterranean hills were more tolerant to the fragmentation than species with big workers (> 8 mm long) dwelling only in anthills with epiterranean hills composed of vegetable and mineral particles.     

Forest Structure Affects the Stoichiometry of Periphyton Primary Producers in Mountain Streams of Northern Patagonia

Riparian zones are major components of stream ecosystems that influence the physical, chemical, and biological parameters. In particular, the distribution of vertical foliage and the structure of riparian vegetation determine light availability in canopied streams. Here, we analyzed how forest structure will modify light availability and thus affect primary producers’ photosynthetic parameters and the periphyton stoichiometry of mountain streams. We carried out field sampling in four streams with different canopies located in the North-Patagonian Andes and conducted a field experiment in which light conditions were manipulated for four months. Then, we linked our results to qualitative climate change scenarios for North-Patagonian forest predicting how future climate change will affect primary producers and periphyton stoichiometry in low-order streams through modifications in the structure of canopied zones. Finally, we found that biomass, photosynthetic parameters and the elemental content of periphyton exhibited a bell-shaped relationship with light availability which was, in turn, dependent on canopy cover. These trends are characterized by an increase from low light up to 250 μmol m^?2 s^?1 and a decline when light is over 750 μmol m^?2 s^?1. Thus, intermediate light resulted in optimal conditions for primary producers’ photosynthesis; however, these intermediate canopied zones are predicted to decrease in the future. Therefore, we predict changes in stream ecosystem stoichiometry due to variations in primary producers’ photosynthesis, and, consequently, periphyton elemental composition as an outcome of forest structure modifications due to climate change.     

Impact of Weight‐Cycling History on Bone Density in Obese Women

Objective: The purpose of this study was to examine the effect of weight cycling (as defined by the frequency and magnitude of intentional weight loss) on bone mineral density and bone mineral content in obese sedentary women. Research Methods and Procedures: Bone mineral content and density measured by DXA, submaximal physical fitness assessment, nutrient intake, oral contraceptive use, and weight‐cycling history were assessed in 195 healthy, overweight sedentary women (age, 21 to 45 years; body mass index, 27 to 40 kg/m²) before beginning a behavioral weight‐loss intervention. Results: After controlling for body weight, multivitamin use, oral contraceptive/estrogen use, and calcium and magnesium intake, women who had a history of weight cycling did not have significantly lower total‐body bone mineral content or density or total femur bone mineral density. In addition, 99% of subjects were above or within one SD of age and gender normative data for total femur bone mineral density. Discussion: It does not seem that a history of weight cycling has an adverse affect on total femur and total‐body bone mineral density in overweight sedentary premenopausal women.     

Calcium weathering in forested soils and the effect of different tree species

Soil weathering can be an important mechanism to neutralize acidity inforest soils. Tree species may differ in their effect on or response to soilweathering. We used soil mineral data and the natural strontium isotope ratio⁸⁷Sr/⁸⁶Sr as a tracer to identify the effect of treespecies on the Ca weathering rate. The tree species studied were sugar maple(Acer saccharum), hemlock (TsugaCanadensis), American beech (Fagusgrandifolia),red maple (Acer rubrum), white ash (FraxinusAmericana) and red oak (Quercus rubra) growingin a forest in northwestern Connecticut, USA. Three replicated sites dominatedby one of the six tree species were selected. At sugar maple and hemlock sitesthe dominant mineral concentrations were determined at three soil depths. Ateach site soil, soil water and stem wood of the dominant tree species weresampled and analyzed for the ⁸⁷Sr/⁸⁶Sr ratio, total SrandCa content. Atmospheric deposition was collected and analyzed for the sameconstituents. Optical analysis showed that biotite and plagioclaseconcentrations were lower in the soil beneath hemlock than beneath sugar mapleand suggested species effects on mineral weathering in the upper 10cm of the mineral soil. These results could not be confirmed withdata obtained by the Sr isotope study. Within the sensitivity of the Sr isotopemethod, we could not detect tree species effects on Ca weathering andcalculatedCa weathering rates were low at all sites (< 60mgm^–2yr^–1). Wefound a positive correlation between Ca weathering and the total Caconcentration in the surface soil. These results indicate that the absolutedifferences in Ca weathering rate between tree species in these acidic surfacesoils are small and are more controlled by the soil parent material(plagioclasecontent) than by tree species.     

Energy analysis of the coal fuel cycle in an appalachian coal county

Preliminary results from an energy analysis of the coal fuel cycle in an Appalachian coal county have provided a systematic assessment of hidden energy subsidies in extraction, transport, processing, and combustion. Current results indicate that the system operates at an annual energy deficit of approximately 350 × 10¹⁰ kcal. A major loss is depletion of the coal resource base by use of inefficient mining techniques. Although of smaller magnitude, reductions in work force and community productivity from occupational accidents, disease, and road maintenance requirements for transport also appear to be significant. Further assessment is needed to verify assumptions and characterize additional data bases.     

The keystone role of leaf-removing crabs in mangrove forests of North Brazil

Principle factors which influence mangroveleaf litter turnover, in particular therole of leaf-removing crabs, were evaluatedin a riverine mangrove site nearBragança (Pará, North Brazil). Ourspecial interest was focussed on the roleof the leaf-removing crab Ucidescordatus. Leaf litter fluxes between themangrove forest and the adjacent estuarywere investigated by estimating the biomassand fate of leaf litter material and propagules. Vegetation is dominated by Rhizophora mangle, with Avicenniagerminans trees, both up to 25 m high,found intermittently. During 1997, Rhizophora trees produced around 1.40 gDW m^-2 d^-1 of leave fall and0.75 g DW m^-2 d^-1 of propagules.Leaf decomposition rates on the ground wereabout 0.06 g DW m^-2 d^-1,irrespective of species, habitat or siteexposure. This amount accounts for <3%of total leaf fall. Average leaf litterbiomass present on the ground was 0.01 gDW m^-2 d^-1. When the mangroveforest was flooded (on average 10 days permonth) the quantity of leaf litterand propagules washed out with the springtide was 10 and 17 times greater thanduring neap tide. Nevertheless, tidalexport and decomposition together made upless than 39 percent of annual leaf litterfall. The bulk of the remaining amount isapparently removed by Ucides. Eachcrab consumed about 1.30 g DW of leaflitter material and propagules per day.Since the average density of these crabswas 1.38 crabs m^-2, it is proposedthat Ucides is a keystone species inBragantinian mangroves.     

Estimating the abundance of subterranean propagules of submersed aquatic plants

1. Data on sample means (x|) and variances (s²) of propagule abundance for five typos of aquatic plants growing in a variety of habitats were collected. The data set consisted of 379 values for x| and s², based on 4942 individual sample units (sediment samples), drawn from the literature or from data collected as part of this study. 2. Regression analysis relating log s² to log x| yielded an equation which was solved for the number of sample units (n) required to achieve a given degree of precision. For precise estimates [standard error (SE) = 20% of x|], values of n between twenty-seven and 234 are required when propagule density is low (<200m^?2), whereas eight to twenty-six sample units are required when propaguie density is high (200–1000 m^?2). For larger SE (i.e. 30% of x|), n decreased by about 50%. Sampler area (20 to 1600cm²) did not affect estimates of n. 3. Time required to collect and process sediment cores (collected with either a 5, 10, or 15cm corer) was approximately 7, 10, or 13min, respectively. Combining this information with the required number of samples is useful in planning studies designed to measure changes in the abundance of underground propagules of submersed aquatic plants.     

Physiological responses of Pinus sylvestris to atmospheric ammonia

Summary Young saplings of Pinus sylvestris were fumigated for 3 months with ammonia in concentrations ranging from 0 to 240 g m^-3. Despite the much higher concentrations than normal in the field, no visible damage occurred. Photosynthesis, dark respiration, transpiration and biomass production were stimulated. At 240 g m^-3 with high irradiance (PAR: 950 mol m^-2 s^-1), net photosynthesis was stimulated by 24% and dark respiration by 76%. Intitial light use efficiency was not significantly affected. Transpiration increased, both in the dark and at 950 mol m^-2 s^-1 by 40% and 57%, respectively. In the presence of ammonia, stomatal control was less efficient. Though growth of roots was not affected by NH₃, that of current year needles was stimulated, resulting in an increased mass ratio of needles to roots. The nitrogen content of the needles increased, but the contents of other mineral components did not change significantly. Due to increased transpiration per unit of needle area and increased mass of needles per tree, water loss per tree was about twice as high in the treatment with 240 g m^-3 as in the control. Towards the end of fumigation, a 10-day period without water supply followed and then the water potential of the shoots was measured as an indicator of water demand. This demand was higher with higher concentrations of NH₃, suggesting a higher risk of injury from drought.     

Changes in chemical compositions of substrates before and after <Emphasis Type="Italic">Ganoderma lucidum</Emphasis> cultivation

After the commercial cultivation of Ganoderma lucidum, that is becoming increasingly popular because of its valuable medicinal effects, a large amount of Ganoderma spent substrate (GSS) remains as a residual material. It is important to identify differences in the chemical compositions among GSS to indicate their suitability. This study was carried out to characterize and evaluate the substrates and GSS for the some chemical contents such as; pH, EC, organic carbon (C), total nitrogen (N), macro and micro elements and C:N ratios. The substrates were prepared by the mixtures of hornbeam and oak sawdust supplemented with wheat bran in a ratio of 20% (20WB) and tea manufacture waste in different ratios (10, 15, 20 and 25%). Organic C, C:N and pH values decreased in GSS, while N, P, K, Mg, Fe, Mn and Zn contents increased. EC and pH values of GSS varied between 1.13 and 2.33 dS m⁻¹, and 5.14 and 5.69, respectively. GSS was found rich in all investigated mineral nutrients. The highest increases in all nutrient contents were generally determined in hornbeam sawdust with 20TW spent substrate. Initial mineral composition of the wastes influenced the mineral composition of the substrates and spent substrates.     

Sleep Duration Trajectories and Body Composition in Adolescents: Prospective Birth Cohort Study

We aimed to estimate the association between sleep duration trajectories and body composition in adolescents. We used data from participants of the 1993 Pelotas (Brazil) Birth Cohort Study who were later followed up at age 18 years (response rate of 81.3%). At the time, 3974 adolescents had complete data on body composition, which was assessed by air displacement plethysmography. Sleep duration was self-reported by participants at ages 11 and 18 years. Analyses were sex-stratified. The mean sleep duration at 11 years was 9.7 (SD 1.4) and 8.4 (SD 1.9) at 18 years. Sleep duration was dichotomized as inadequate (<8 hours/day) or adequate (≥8 hours/day). Mean body mass, fat mass, and fat-free mass indices at 18 years were 23.4 kg/m² (SD 4.5), 6.1 kg/m² (SD 3.9) and 17.3 kg/m² (SD 2.5), respectively. Girls who reported inadequate sleep duration at 11 years of age, but adequate sleep duration at 18, on average experienced an increase in body mass index (β = 0.39 z-scores; 95% CI 0.13, 0.65), fat mass index (β = 0.30 z-scores; 95% CI 0.07, 0.53), and fat-free mass index (β = 0.24 z-scores; 95% CI 0.08, 0.39) compared to those who had adequate sleep duration at both time points. The results suggest that changes in sleep duration across adolescence may impact body composition in later adolescence and that this may differ by sex.     

ALGAL COMMUNITY STRUCTURE OF THE EAST AND WEST FLOWER GARDEN BANKS,NORTHWESTERN GULF OF MEXICO

The algal communities of the Flower Garden Banks National Marine Sanctuary have not been comprehensively evaluated and only a few dominant macroalgal species have been reported. This study utilizes both destructive and non‐destructive sampling techniques to characterize and taxonomically identify the ‘algal mat’ community structure. The East and West Flower Garden Banks are located on the outer continental shelf approximately 200 km off the Texas‐Louisiana coastline. The average depth of both banks is 100 m with the crest approximately 20 m from the surface. Harvest and photogrammetric samples were collected during two extended cruises to the Flower Garden Banks in October 1998 and March 1999. Forty, 0.25‐m² quadrats of standing stock material were randomly collected along with one hundred sixty‐one 0.25 m² photo‐quadrats from an average depth of 27 m. Photo‐transparencies were projected to an actual size grid with 25 random points. Four thousand twenty‐five transparency points were evaluated and used to calculate percent composition of algal cover. Harvest samples were used to characterize the “algal mat” composition, species richness, abundance, and biomass. Forty‐two species were identified from the samples representing 14 Orders. The “red algal mat” was the dominant algal coverage comprising 38.4% of all photogrammetric samples. This mat was primarily composed of members from the Order Ceramiales. Centroceras, Ceramium, and Polysiphonia comprised 33.4% of the mat, Anotrichium and Hypoglossum, 22.4%.     

14. Studies on Poliomyelitis Virus—Concentration and Purification of the Virus

ABSTRACT

For the purpose of determining the immunogenic potency of polio virus, relatively large amounts of concentrated virus material were prepared which had titres of the order of 10¹⁰ T.C.I.D.jo per ml. These were obtained by pervaporating large quantities of tissue culture fluid containing approximately 10⁶⁵ T.C.I.D.JQ per ml.     

The malonyl gramicidin channel: NMR-derived rate constants and comparison of calculated and experimental single-channel currents

Summary Malonyl gramicidin is incorporated into lysolecithin micelles in a manner which satisfies a number of previously demonstrated criteria for the formation of the transmembrane channel structure. By means of sodium-23 nuclear magnetic resonance, two binding sites are observed: a tight site and a weak site with binding constants of approximately 100m ^–1 and 1m ^–1, respectively. In addition, off-rate constants from the two sites were estimated from NMR analyses to bek _off ^t 3×10⁵/sec andk _off ^w 2×10⁷/sec giving, with the binding constants, the on-rate constants,k _on ^t 3×10⁷/msec andk _on ^w 2×10⁷/m sec.Five different multiple occupancy models with NMR-restricted energy profiles were considered for the purpose of calculating single-channel currents as a function of voltage and concentration utilizing the four NMR-derived rate constants (and an NMR-limit placed on a fifth rate constant for intrachannel ion translocation) in combination with Eyring rate theory for the introduction of voltage dependence.Using the X-ray diffraction results of Koeppe et al. (1979) for limiting the positions of the tight sites, the two-site model and a three-site model in which the weak sites occur after the tight site is filled were found to satisfactorily calculate the experimental currents (also reported here) and to fit the experimental currents extraordinarily well when the experimentally derived values were allowed to vary to a least squares best fit. Surprisingly the best fit values differed by only about a factor of two from the NMR-derived values, a variation that is well within the estimated experimental error of the rate constants.These results demonstrate the utility of ion nuclear magnetic resonance to determine rate constants relevant to transport through the gramicidin channel and of the Eyring rate theory to introduce voltage dependence.