bluuebunny/crossref_metadata_2025 huggingface dataset:
Variability in responses to nutrients and trace elements, and transmission of stressor effects through an estuarine food web
Authors: Breitburg Denise L. , Sanders James G. , Gilmour Cynthia C. , Hatfield Colleen A. , Osman Richard W. , Riedel Gerhardt F. , Seitzinger Sybil P. , Seitzinger Sybil P.
Published: May 2010

Aquatic systems are increasingly exposed to multiple stressors from anthropogenic sources. These stressors can vary in the consistency and magnitude of responses they elicit in biota and in how the presence of additional stressors modifies their effects. Understanding how the biological environment and temporal dynamics influence responses to stressors, and how stressors interact, is important to predicting their effects in the natural environment. We examined temporal variability in responses of an experimental estuarine food web to elevated trace elements and nutrients, as well as non‐additive effects of the combination of these two stressors. Experiments were conducted four times during spring through autumn 1996 in 20 l‐m3 mesocosms. We measured a range of system‐, population‐, and individual‐level parameters to quantify responses of phytoplankton, bacterioplankton, heterotrophic nanoflagellates, copepods, fish, and benthic invertebrates to trace element and nutrient additions. The response to trace element additions was more variable both temporally and among phytoplankton and higher trophic level taxa than was the response to nutrient additions. Most taxa increased, either significantly or showed a trend toward increasing, in response to nutrient additions in all four mesocosm runs. In contrast, the direction as well as the magnitude of responses to trace element additions varied considerably among taxa and experimental runs. Two distinct types of nutrient3trace element interactions were important. First, temporal dynamics of nutrient ratios appeared to affect the temporal pattern of toxicity of trace elements to phytoplankton. Second, in the June mesocosm run when trace element additions reduced production, abundance, or growth of many organisms, these reductions were often proportionately greater in nutrient addition tanks than where no nutrients were added. Our results suggest that considerable temporal and taxonomic variation in responses to trace element loadings are likely to be seen in field settings even under constant loadings to the system and that trace elements may mask the magnitude of the response to high nutrient loadings in eutrophic systems. More generally, the presence of multiple stressors may either increase or dampen the temporal and spatial variability seen in aquatic systems, depending on the interactions among stressors and the influence of background environmental conditions and sensitive species on the expression of stressor effects.
Biogeochemical cycling of PCBs in lakes of variable trophic status: A paired‐lake experiment
Authors: Jeremiason Jeff D. , Eisenreich Steven J. , Paterson Michael J. , Beaty Ken G. , Hecky Robert , Elser James J.
Published: May 2010

A paired whole‐lake experiment was conducted on two remote, atmospherically driven lakes in the Experimental Lakes Area (ELA) to examine the stresses of trophic condition on air‐water exchange and settling fluxes of polychlorinated biphenyls (PCBs). Lake 227 (L227) and Lake 110 (L110) are similar in volume, surface area, and watershed area but differ significantly in trophic status. The two lakes have similar access to atmospheric PCBs but eutrophic L227 may exhibit enhanced air to water exchange due to greater biotic uptake of dissolved PCBs. Settling fluxes of PCB were significantly greater in eutrophic L227 (40 ng m−2 d‐1 in 1993; 29 ng m‐2 d‐1 in 1994) than in oligotrophic L110 (22 ng m‐2 d‐1 in 1993 and 17 ng m‐2 d‐1 in 1994). Dissolved ΣPCB concentrations were not significantly different in the two lakes (∼0.3 ng liter‐1). Greater ΣPCB settling fluxes in L227 vs. L110 coupled with similar dissolved concentrations after June supports the hypothesis that air‐water exchange supports the water column PCB concentrations. Surprisingly, ΣPCB fugacity gradients in both lakes indicated that net volatilization dominated during the entire ice‐free period, requiring another source. A ΣPCB mass budget in the epilimnion of each lake over the stratified period showed that the major PCB losses were due to settling and volatilization. ΣPCB settling losses were 2.4 times greater in L227 than in L110 due to higher settling particle fluxes. The mass budgets suggest that the major PCB input to these remote lakes is from the watershed.
The effect of multiple stressors on the Florida Keys coral reef ecosystem: A landscape hypothesis and a physiological test
Authors: Porter James W. , Lewis Sarah K. , Porter Karen G.
Published: May 2010

Changes in land use and water management practices in south Florida have altered the quality and quantity of freshwater flowing into Florida Bay. By the 1980s, reduced inflow and drought led to an extensive hypersaline phase in the bay. This phase had a drastic effect on benthic communities within the bay and possibly also on coral communities within the bay and the Florida Keys National Marine Sanctuary. Physical oceanographic measurements demonstrate the presence of warm, hypersaline, and turbid water on coral reefs offshore from the Florida Keys, especially near passes which conduct water from Florida Bay to the Atlantic Ocean. To examine the effect of Florida Bay water intrusions on coral reefs, we tested for significant effects of two stressors, elevated temperature and salinity, on coral production, respiration, and survival. Elevated temperatures produce significant reductions in photosynthesis, respiration, and net P : R ratios after 6 h of exposure, and elevated salinities produce similar results after 30 h. Exposure to both elevated temperature and salinity produces a highly significant (P > 0.01), but short ‐term, mitigative interactive effect. The combination of the two stressors was less stressful (for the response variables measured) than the sum of the stressors acting independently. After 36 h of exposure, however, the mitigating effect disappeared and corals exposed to the combined stresses did not survive. A three ‐dimensional response surface, which predicts P:R ratios as a function of varying salinity and temperature, is used to construct a testable hypothesis to explain recent declines in coral cover on some reefs within Florida Bay and the Florida Keys. We chose salinity and temperature to test a multiple stressor model because they are relatively easy to manipulate. However, any enviromentally realistic model must include other potential stressors, such as turbidity, elevated nutrients, and environmental contaminants.
Manipulating iron availability in nearshore waters
Authors: Wells Mark L.
Published: May 2010

The consideration of iron effects on marine ecosystems has focused mainly on high‐nitrate low‐chlorophyll regions, but iron likely has an equally important regulatory role in coastal waters. Iron requirements of neritic phytoplankton not only are comparatively high but also differ substantially among species, so that iron fluctuations within metal‐replete systems should strongly influence the composition and distribution of phytoplankton assemblages. But unlike the simplicity of testing iron effects in iron‐depleted waters, ascertaining iron effects in apparently replete waters has been forestalled by a lack of experimental tools that can regulate iron availability independent of other bioactive metals in seawater. I present here the results of size‐fractionated shipboard culture experiments using the fungal siderophore desferriferrioxime B (DFB) to regulate iron availability in coastal upwelling waters. Addition of excess DFB essentially eliminated 59Fe uptake by both phytoplankton and heterotrophic bacteria over a 6‐h period and allowed only marginal iron uptake over 5 d of incubation. Carbon uptake by small (0.2–5.0‐ µm) phytoplankton was immediately curtailed upon addition of DFB, signifying a rapid onset of iron stress. In contrast, short‐term (0–6 h) carbon uptake by larger (&5.0‐ µm) phytoplankton was not affected, indicating that larger cells contained significant iron reserves. Nonetheless, carbon assimilation was substantially lower in DFB treatments relative to the controls after 5 d of incubation. Uptake of 54Mn, 65Zn, and 57Co was not immediately affected by DFB but then slowed after 4 h and was significantly lower after 5 d, presumably because iron limitation lowered the cellular requirements for these bioactive metals. These findings demonstrate that DFB can be used to manipulate biologically accessible iron to determine how iron affects algal community structure and carbon cycling in iron‐replete waters.
Inducing phytoplankton iron limitation in iron‐replete coastal waters with a strong chelating ligand
Authors: Hutchins D. A. , Franck V. M. , Brzezinski M. A. , Bruland K. W.
Published: May 2010

Dissolved iron (Fe) concentrations in the California coastal upwelling regime vary over two orders of magnitude (from >0.05 to <5 nM), which leads to a wide range in Fe effects on phytoplankton growth. Fe‐addition experiments are appropriate to use to assess the biological role of Fe in low‐Fe areas, but other methods are needed in Fe‐replete regions. We present experiments that use additions of the exogenous siderophore desferrioxamine B (DFOB, obtained from a terrestrial actinomycete fungus) to sequester ambient Fe and to markedly decrease its availability to the biota. DFOB additions resulted in artificial Fe limitation of the phytoplankton community in high‐Fe areas of the upwelling region. Results of these ‘Fe‐removal’ experiments mirror those of Fe‐addition experiments in low‐Fe, high‐nutrient, low‐chlorophyll (HNLC) waters. When DFOB is added to Fe‐replete waters, changes in nutrient concentrations, biomass, and other biological parameters closely resemble those seen in Fe limited controls in HNLC areas, while the controls without DFOB behave much like HNLC Fe‐addition bottles. DFOB additions in high‐Fe waters greatly reduced biological Fe uptake and, consequently, nitrate, silicic acid, and carbon‐uptake rates as well as particulate production. Diatoms and other phytoplankton bloomed profusely in unamended controls but not in Fe‐limited 1DFOB bottles. Bacterial numbers and zooplankton grazing activity were also severely reduced in DFOB‐addition bottles. These experiments demonstrate that artificially lowering Fe availability can induce limitation of autotrophic and heterotrophic plankton and can prevent utilization of the high ambient levels of upwelled nutrients along the California coast. Our results suggest that DFOB‐bound Fe is highly unavailable to the plankton community, a result that offers researchers an important tool to use to probe the influence of Fe on biological community development in high‐Fe regimes.
Particle selectivity, gut volume, and the response to a step change in diet for depositfeeding polychaetes
Authors: Bock Michael J. , Miller Douglas C.
Published: May 2010

We performed a series of experiments to examine the aspects of deposit feeding that were relevant to studies of resource variability over short time scales. We examined particle‐size selectivity, gut volume, gut residence time, and the response to a change in diet in three polychaete species: Spiochaetopterus oculatus, Spio setos and Marenzelleria viridis. All three species were particle‐size selective and had similar gut volumes and gut residence times. Thus, measurements of bulk sediment characteristics are largely irrelevant to the studies of their nutrition. In response to a step change in diet, changes in the egestion rate were accomplished by smooth transitions between steady‐state rates occurring over 1 to 2 h. The form of this modulation suggests that these organisms do not respond to changes in diet by temporarily retaining or flushing the material in the gut in order to increase digestive yield. The time scale of the response to a change in diet provides evidence for a foregut/midgut feedback mechanism for inducing changes in feeding rate due to sediment food concentration. If the time required to modulate the feeding rate to a new steady state is more rapid than the time scale of food‐resource variability in the field, it is unlikely that a response other than a gradual transition to a new ingestion rate would provide a significant advantage.
Storage of marine particulate samples for light𠅀absorption measurements
Authors: Sosik Heidi M.
Published: May 2010

Spectral absorption studies of marine particulates by spectrophotometry usually require the concentrating of material, and it is often desirable to store concentrated samples prior to analysis. The effects of various storage methods for particles collected on glass‐fiber filters were examined using natural marine particles. Sensitivity to storage effects differed for particles collected from different environments, but results consistently indicated that refrigeration for more than a few hours and freezing at −10°C are inadequate for preserving absorption by phytoplankton pigments in the visible region of the spectrum. Storage at −80°C and at liquid‐nitrogen temperatures was found to be satisfactory, with liquid nitrogen providing the most reliable results for the longest periods evaluated (up to 1 yr). Increases in absorption were observed at ultraviolet wavelengths under all storage conditions, which suggests that optical properties in this region of the spectrum cannot be reliably assessed unless samples are analyzed immediately after collection.
Determining optical absorption of colored dissolved organic matter in seawater with a liquid capillary waveguide
Authors: D'Sa Eurico J. , Steward Robert G. , Vodacek Anthony , Blough Neil V. , Phinney Dave
Published: May 2010

Optical absorption spectra of 0.2‐μm filtered sea‐water samples originating from diverse oceanic and coastal waters were measured with a long pathlength capillary wave‐guide; results were compared with those of three different lab‐oratory spectrophotometers. The 0.5‐m long 550‐ µm (inside diameter) aqueous waveguide uses only 120 ml of filtered sea‐water, making it convenient for use in flow‐through cells or when sample volumes are restricted. Source light propagates inside the capillary waveguide by total internal reflection because of the lower refractive index of the waveguide walls with respect to the aqueous core. The absorption coefficient of colored dissolved organic matter (CDOM) at 355 nm and S, the slope of the log linearized CDOM absorption spectra, were determined for all samples. The CDOM absorption spec‐tra measured by the capillary waveguide closely matched that measured by spectrophotometers for CDOM concentrations varying over an order of magnitude. The deviations between the absorption spectra obtained with the capillary waveguide and those obtained with the standard spectrophotometers increased with decreasing total absorption and with increase in wavelength, presumably because of the greater baseline offsets observed in the capillary waveguide. The offsets are due to differences in refractive indices between the seawater samples and the freshwater reference. With a suitable reference, the capillary waveguide will be very useful for monitoring surface seawater CDOM absorption semicontinuously.
Trophic interactions in open systems: Effects of predators and nutrients on stream food chains
Authors: Forrester Graham E. , Dudley Tom L. , Grimm Nancy B.
Published: May 2010

Theory and empirical work on food chains has focused primarily on closed, equilibrial environments. We tested the combined effects of secondary consumers (fish) and limiting nutrients (nitrogen) on intermediate trophic levels in an open stream environment, where flow redistributes organisms and materials among patches of streambed habitat. Fish reduced the biomass of the dominant herbivore (baetid mayflies) within habitat patches both by direct predation and by causing increased emigration from the patches. The resulting decrease in herbivory caused an increase in the growth and biomass of primary producers (algae) in areas containing fish. Independent of the effect of fish, algal growth and biomass was increased by augmenting the nutrient supply to patches. Nutrient‐enriched areas (with high algal biomass) also supported greater populations of herbivores because they either grew faster in these areas or emigrated less frequently from them. Controlling influences on trophic structure came from both the top and the bottom of the food chain, and these influences were not conditional upon one another. Trophic structure in this system was determined by a mix of behavioral and trophic interactions between the major taxa, most of which were specific to open systems and not predicted by conventional theory.
High‐pressure size exclusion chromatography analysis of dissolved organic matter isolated by tangential‐flow ultrafiltration
Authors: Everett Christopher R. , Chin Yu-Ping , Aiken George R.
Published: May 2010

A 1,000‐Dalton tangential‐flow ultrafiltration (TFUF) membrane was used to isolate dissolved organic matter (DOM) from several freshwater environments. The TFUF unit used in this study was able to completely retain a polystyrene sulfonate 1,800‐Dalton standard. Unaltered and TFUF‐fractionated DOM molecular weights were as‐sayed by high‐pressure size exclusion chromatography (HPSEC). The weight‐averaged molecular weights of the retentates were larger than those of the raw water samples, whereas the filtrates were all significantly smaller and approximately the same size or smaller than the manufacturer‐specified pore size of the membrane. Moreover, at 280 nm the molar absorptivity of the DOM retained by the ultrafilter is significantly larger than the material in the filtrate. This observation suggests that most of the chromophoric components are associated with the higher molecular weight fraction of the DOM pool. Multivalent metals in the aqueous matrix also affected the molecular weights of the DOM molecules. Typically, proton‐exchanged DOM retentates were smaller than untreated samples. This TFUF system appears to be an effective means of isolating aquatic DOM by size, but the ultimate size of the retentates may be affected by the presence of metals and by configurational properties unique to the DOM phase.
Acetate retention and metabolism in the hyporheic zone of a mountain stream
Authors: Baker Michelle A. , Dahm Clifford N. , Valett H. Maurice
Published: May 2010

An in situ acetate injection was used to determine the influence of labile dissolved organic carbon (DOC) availability on microbial respiration in the hyporheic zone of a headwater stream. We added bromide as a conservative tracer and acetate as an organic substrate to the hyporheic zone of Rio Calaveras, New Mexico, via an injection well. Tracer was observed in four of eight capture wells. Three of the four wells showed increases in bromide without concurrent increases in acetate concentration, suggesting 100% acetate retention. One well had 38% acetate retention. Pore velocity and acetate retention were negatively correlated, suggesting hydrologic control of acetate retention. Acetate did not significantly sorb to the sandy hyporheic sediments at this site, indicating biological consumption of acetate. Acetate addition stimulated total CO2 production along monitored flowpaths and led to changes in solutes associated with microbial terminal electron‐accepting processes (TEAPs). Dissolved oxygen (DO), nitrate, and sulfate significantly decreased, and ferrous iron and methane significantly increased compared to background concentrations in most wells. These results support the hypothesis that microbial respiration in the hyporheic zone is limited by labile DOC availability. Furthermore, we have shown that a suite of metabolic processes, from aerobic respiration to methanogenesis, cooccur and that anaerobic processes dominate heterotrophic metabolism in the hyporheic zone of Rio Calaveras.
Implications of bio‐optical modeling of phytoplankton photosynthesis in Antarctic waters: Further evidence of no light limitation in the Bransfield Strait
Authors: Figueiras Francisco G. , Arbones Belén , Estrada Marta
Published: May 2010

During the cruise ECOANTAR 94 photosynthesis versus irradiance relationships, phytoplankton spectral absorption, quantum yield of carbon fixation, and water column light regime were determined in the eastern Bransfield Strait and surrounding areas of the Weddell Sea and Weddell‐Scotia Confluence, to determine if photosynthesis is light limited in these areas. There were no significant differences in the light‐saturated chlorophyll‐specific rate of photosynthesis (P Bm), light‐limited slope (±B), light saturation parameter (EkPAR), and the maximum quantum yield (Φm) between surface and subsurface water for several water masses in the area, which indicates that the photosynthetic response in the upper mixed layer was uniform. There were also no significant differences between the spectral light saturation parameter (EkPUR) and the mean absorbed irradiance by phytoplankton in the upper mixed layer (EumlPUR). These similarities suggest that phytoplankton photosynthesis was not light limited in this Antarctic region during the cruise period. This was also affirmed by the fact that the average operational quantum yield of the water column (0.03 mol C [mol photons]−1) was half of the mean maximum quantum yield (0.06 mol C [mol photons]−1). Primary production is underestimated by 24% when broadband models are compared with spectral ones. These results have important implications for the modeling of carbon flows in the Southern Ocean.
Food type and concentration affect chlorophyll and carotenoid destruction during copepod feeding
Authors: McLeroy‐Etheridge Stacey L. , McManus George B.
Published: May 2010

To evaluate the use of pigments as tracers for determining copepod grazing rates and selectivity, we examined the stability of several biomarker pigments during copepod feeding incubations. During these incubations, we measured changes in phytoplankton‐derived chlorophylls and carotenoids in the particulate and dissolved pools. Budgets were calculated to determine changes in pigment concentrations in the food, copepod fecal pellets, copepod guts, and dissolved/colloidal fraction. For each of six algal diets, adult female Acartia tonsa copepods were fed limiting and saturating food concentrations, approximately 100 and 500 µg C L−1 , respectively. Thalassiosira weissflogii, Rhodomonas lens, Chroomonas salina, Dunaliella tertiolecta, and two Tetraselmis strains were used in the feeding experiments to investigate the fate of fucoxanthin, alloxanthin, lutein, chlorophyll (Chl) b, and Chl a. In all experiments using saturating food concentrations, the dissolved/colloidal pool contained no more than 3% (usually less than 1%) of any pigment, whereas in experiments using limiting food conditions, pigments were undetectable in the dissolved/colloidal pool. Pheopigments were present in fecal pellets and copepod guts in most of the experiments. Chl a destruction (conversion to colorless products) was variable among the different experiments, depending on algal species and food concentration and, in most cases, Chl a was destroyed to a greater extent than the carotenoids. In all cases, pigment destruction was higher when copepods were fed limiting rather than saturating food concentrations. These data attribute the variability in pigment destruction to algal species and concentration, and suggest caution when pigments are used as tracers of herbivory. In such studies, assumptions about conservative behavior, even for the carotenoids, would need to be verified for each set of experimental conditions and grazers.
The effect of calcium concentration on the calcification of Daphnia magna
Authors: Alstad Nina E. W. , Skardal Liz , Hessen Dag O.
Published: May 2010

Soft waters are characterized by low Ca concentrations, and the distribution and relative success of Ca‐demanding invertebrates could be limited by low Ca in extreme softwater localities. A further Ca depletion caused by reversed acidification could thus seriously affect freshwater crustaceans. Experimental studies on the calcification and Ca content of Daphnia magna clearly suggested the potential of a Ca limitation. Saturated calcification was reached at Ca concentrations >0.13 mM. Individuals reared in media with lower Ca concentrations were unable to compensate by increasing the period of postmolt Ca uptake and thus had a lower specific Ca content. Specific Ca content decreased from 4.2% to 1% of dry weight over the range 0.25–0.013 mM Ca. Even at the low Ca concentrations, only 10% of total Ca was reclaimed upon molting, the rest was lost with the old exuviae (∼40%) or to the ambient medium (∼50%). This incomplete calcification under low ambient Ca concentrations could represent a competitive drawback in Ca‐poor waters.
Exploring the Effectiveness of Occupational Therapy Interventions, Other Than the Sensory Integration Approach, With Children and Adolescents Experiencing Difficulty Processing and Integrating Sensory Information
Authors: Polatajko Helene J. , Cantin Noemi
Published: June 2010

This literature review was completed as part of the Evidence-Based Literature Review Project of the American Occupational Therapy Association to explore the effectiveness of occupational therapy interventions with children and adolescents experiencing difficulty processing and integrating sensory information. This part of the review focused on interventions other than the sensory integration approach. Twenty articles (reporting on 21 studies) met the inclusion criteria. This systematic review found that children with difficulty processing and integrating sensory information and difficulties with the performance of daily occupations can benefit from intervention. However, the great variability that characterizes this literature in terms of populations, interventions, and study quality precludes the formation of any firm conclusions regarding specific approaches. There is an urgent need for well-controlled studies examining the effectiveness of frequently used pediatric occupational therapy interventions with well-defined, homogeneous populations on outcomes that target participation in everyday life.
Relationships Between Stereotyped Movements and Sensory Processing Disorders in Children With and Without Developmental or Sensory Disorders
Authors: Gal Eynat , Dyck Murray J. , Passmore Anne
Published: June 2010

OBJECTIVE. Stereotyped movements (SM) are a defining characteristic of autism but are also present in children with a range of sensory and developmental disorders. We examined whether the severity of sensory processing disorders (SPD) was associated with the severity of SM and whether SPD accounted for between-group differences in SM.

METHOD. The Short Sensory Profile and the Stereotyped and Self-Injurious Movements Interview were administered to children with autism, intellectual disability, visual impairment, and hearing impairment and to typically developing children.

RESULTS. SPD predicted the severity of SM in all samples and accounted for differences in SM between the groups. Other differences in the severity of SM were the result of diagnosis and the interaction between diagnosis and an intellectual disability.

CONCLUSION. SPD may be a source of SM, but functional connections between these phenomena will need to be tested in future research. Implications for occupational performance are addressed.
Quality of Life in American Indian Women With Arthritis or Diabetes
Authors: Poole Janet L. , Cordova Jennifer Schukar , Sibbitt Wilmer L. , Skipper Betty
Published: June 2010

OBJECTIVE. We investigated quality of life (QOL) in American Indian women with different chronic diseases.

METHOD. Sixty American Indian women with diabetes mellitus (DM), rheumatoid arthritis (RA), or both DM and RA (DM + RA), and healthy control women received evaluations of joint motion, hand strength dexterity, pain, activity and participation limitations and QOL.

RESULTS. The DM + RA and RA groups had significantly more pain, less joint motion, decreased hand strength, and more activity limitations. Participation was similar for all groups except the DM + RA group. Past and present QOL were similar; however, the DM + RA group reported significantly decreased future QOL.

CONCLUSION. Results suggest that the presence of more than one chronic disease affects activity and participation. Factors that related to QOL were different for each disease group, with the exception of pain. Identification of factors related to QOL can help occupational therapists identify areas for intervention.
Curiosity Didn't Kill this Cat: Studs Terkel for English Language Learners
Authors: KELLY SUSAN
Published: June 2010

After years of studying academic English, many students are ready to move beyond language designed for the classroom, or what Yoshida (2001) calls “fishbowl” English, to the language of the “open sea.” As students develop beyond the beginner level, they are ready to read and discuss appropriate authentic texts. Even students who are unsure of themselves can make it in the “open sea” and navigate quite well with help from teachers and peers. Studs Terkel's work is appropriate material that captures U.S. culture in all its vitality, complexity, and variety. With some scaffolding, teachers can use Terkel's work to help students understand authentic English and gain insight into U.S. culture. To sharpen the focus of students' study, I have created reading, writing, and discussion activities based on Terkel's writing and oral history interviews with Americans with distinct perspectives and backgrounds, from factory workers to CEOs. Studying these individuals gives students living examples of the principles discussed in our text.
Airborne measurements of aerosol optical properties related to early spring transport of mid-latitude sources into the Arctic
Authors: de Villiers R. A. , Ancellet G. , Pelon J. , Quennehen B. , Schwarzenboeck A. , Gayet J. F. , Law K. S.
Published: June 2010

Abstract. Airborne lidar and in-situ measurements of the aerosol properties were conducted between Svalbard Island and Scandinavia in April 2008. Evidence of aerosol transport from Europe and Asia is given. The analysis of the aerosol optical properties based on a multiwavelength lidar (355, 532, 1064 nm) including volume depolarization at 355 nm aims at distinguishing the role of the different aerosol sources (Siberian wild fires, Eastern Asia and European anthropogenic emissions). Combining, first aircraft measurements, second FLEXPART simulations with a calculation of the PBL air fraction originating from the three different mid-latitude source regions, and third level-2 CALIPSO data products (i.e. backscatter coefficient 532 nm,volume depolarization and color ratio between 1064 and 532 nm in aerosol layers) along the transport pathways, appears a valuable approach to identify the role of the different aerosol sources even after a transport time larger than 4 days. Optical depth of the aerosol layers are always rather small (<4%) while transported over the Arctic and ratio of the total attenuated backscatter (i.e. including molecular contribution) provide more stable result than conventional aerosol backscatter ratio. Above Asia, CALIPSO data indicate more depolarization (up to 15%) and largest color ratio (>0.5) for the northeastern Asia emissions (i.e. an expected mixture of Asian pollution and dust), while low depolarization together with smaller and quasi constant color ratio (≈0.3) are observed for the Siberian biomass burning emissions. A similar difference is visible between two layers observed by the aircraft above Scandinavia. The analysis of the time evolution of the aerosol optical properties revealed by CALIPSO between Asia and Scandinavia shows a gradual decrease of the aerosol backscatter, depolarization ratio and color ratio which suggests the removal of the largest particles in the accumulation mode. A similar study conducted for a European plume has shown aerosol optical properties intermediate between the two Asian sources with color ratio never exceeding 0.4 and moderate depolarization ratio being always less than 8%, i.e. less aerosol from the accumulation mode.
Dynamic Adjustment of Climatological Ozone Boundary Conditions for Air-Quality Forecasts
Authors: Makar P. A. , Gong W. , Mooney C. , Zhang J. , Davignon D. , Samaali M. , Moran M. D. , He H. , Tarasick D. W. , Sills D. , Chen J.
Published: June 2010

Abstract. Ten different approaches for applying lateral and top climatological boundary conditions for ozone have been evaluated using the off-line regional air-quality model AURAMS. All ten approaches employ the same climatological ozone profiles, but differ in the manner in which they are applied, via the inclusion or exclusion of (i) a dynamic adjustment of the climatological ozone profile in response to the model-predicted tropopause height, (ii) a sponge zone for ozone on the model top, (iii) upward extrapolation of the climatological ozone profile, and (iv) different mass consistency corrections. The model performance for each approach was evaluated against North American surface ozone and ozonesonde observations from the BAQS-Met field study period in the summer of 2007. The original daily one-hour maximum surface ozone biases of about +15 ppbv were greatly reduced (halved) in some simulations using alternative methodologies. However, comparisons to ozonesonde observations showed that the reduction in surface ozone bias sometimes came at the cost of significant positive biases in ozone concentrations in the free troposphere and upper troposphere. The best overall performance throughout the troposphere was achieved using a methodology that included dynamic tropopause height adjustment, no sponge zone at the model top, extrapolation of ozone when required above the limit of the climatology, and no mass consistency corrections (global mass conservation was still enforced). The simulation using this model version had a one-hour daily maximum surface ozone bias of +8.6 ppbv, with small reductions in model correlation, and the best comparison to ozonesonde profiles. This recommended and original methodologies were compared for two further case studies: a high-resolution simulation of the BAQS-Met measurement intensive, and a study of the downwind region of the Canadian Rockies. Significant improvements were noted for the high resolution simulations during the BAQS-Met measurement intensive period, both in formal statistical comparisons and time series comparisons of events at surface stations. The tests for the downwind-Rockies region showed that the coupling between vertical transport associated with troposphere/stratosphere exchange, and that associated with boundary layer turbulent mixing, may contribute to ozone positive biases.
Seven years of measurements of aerosol scattering properties, near the surface, in the southwestern Iberia Peninsula
Authors: Pereira S. N. , Wagner F. , Silva A. M.
Published: June 2010

Abstract. Aerosol scattering properties, near the surface, were measured over a period of seven years (2002–2008) at Évora, Portugal. This long time series provides valuable information on light scattering by aerosols, namely related with their climatology and with their direct effect on climate. The average (and median) scattering coefficient, at the wavelength of 550 nm, and the scattering Ångström exponent were found to be 42.5 Mm−1 (29.9 Mm−1) and 1.4 (1.5) respectively, indicating that scattering is, in general, of moderate magnitude and dominated by fine particles. Both seasonal and daily cycles were shown, which were related to local production as well as with transport of particles from elsewhere. The average summer and winter values of the scattering coefficient (47 and 54 Mm−1 respectively), at the wavelength of 550 nm, correspond to a significant increase in the aerosol particle concentration when compared with spring and fall (35 and 37 Mm−1 respectively); also the simultaneous increase of the Ångström exponent, from 1.2–1.4 towards 1.4–1.6, is consistent with the input of fine particles from anthropogenic origin in winter and forest fires in summer. Back-trajectory analysis indicate that the site was regularly under the influence of clean air masses from Atlantic area, with low particle loads (low scattering coefficients) but as the influence of transport from the continent (Iberia Peninsula) increased, the aerosol particle load was observed to increase as well as the relative importance of fine particles over coarse ones, approaching the features observed during European air masses influence.
Organic nutrients as sources of N and P to the upper layers of the North Atlantic subtropical gyre along 24.5° N
Authors: Landolfi A. , Dietze H. , Koeve W. , Mather R. , Sanders R.
Published: May 2010

Abstract. There is a longstanding discussion on how the macronutrient requirement of the export production in the North Atlantic subtropical gyre is sustained. In this study we asses the role of dissolved organic nitrogen (DON) and phosphorous (DOP) as sources of new nutrients into the North Atlantic subtropical gyre at 24.5° N. We define, based on measurements of DON, DOP, phytoplankton community structure, stable nitrogen isotopic signals, surface mixed layer depth and ocean color as viewed from space, four regions characterized by different nutrient supply regimes. Within these regions, two distinct loci of N2 fixation occur associated with different plankton assemblages and separated by a region in which N2 fixation occurs at levels insufficient to leave its distinctive isotopic fingerprint on the isotopic composition of PON. Here, the phosphorus supply pathways to the mixed plankton assemblage appear to be different. In the wester oligotrophic gyre (70–46° W), the lateral advection of DOP supplies the missing P that, together with, shallow mixed layer, almost permanent stratification and high water temperatures, stimulate diazotrophic growth, which augment TON local accumulation. In the eastern oligotophic gyre (46–30° W), DOP cannot support the P demand as it is exhausted on its way from productive areas. This is inferred from DOP turnover rates, estimated form enzymatic clevage rates, which are shorter (11 ± 8 months) than transit timescales, estimated from a 3-D circulation model (>4 yr). A stronger seasonal cycle in chlorophyll and mixed layer depth, favour some nutrient injections from below. Here additional N sources come from the advected DON which has a turnover-time of 6.7 ± 3 yr, instead fast remineralization and little DOP export are needed to maintain the P requirements. We conclude from these observations that organic nutrient utilisation patterns drive diverse phytoplankton assemblages and oceanic nitrogen fixation gradients.
Water vapour source impacts on oxygen isotope variability in tropical precipitation during Heinrich events
Authors: Lewis S. C. , LeGrande A. N. , Kelley M. , Schmidt G. A.
Published: June 2010

Abstract. Water isotope records such as speleothems provide extensive evidence of past tropical hydrological changes. During Heinrich events, isotopic changes in monsoon regions have been interpreted as implying a widespread drying through the Northern Hemisphere tropics and an anti-phased precipitation response in the south. Here, we examine the sources of this variability using a water isotope-enabled general circulation model, Goddard Institute for Space Studies ModelE. We incorporate a new suite of vapour source distribution tracers to help constrain the impact of precipitation source region changes on the isotopic composition of precipitation and to identify nonlocal amount effects. We simulate a collapse of the North Atlantic meridional overturning circulation with a large freshwater input to the region as an idealised analogue to iceberg discharge during Heinrich events. An increase in monsoon intensity, defined by vertical wind shear, is modelled over the South American domain, with small decreases simulated over Asia. Simulated isotopic anomalies agree well with proxy climate records, with lighter isotopic values simulated over South America and enriched values across East Asia. For this particular abrupt climate event, we identify which climatic change is most likely linked to water isotope change – changes in local precipitation amount, monsoon intensity, water vapour source distributions or precipitation seasonality. We categorise individual sites according to the climate variability that water isotope changes are most closely associated with, and find that the dominant isotopic controls are not consistent across the tropics – simple local explanations, in particular, fall short of explaining water isotope variability at all sites. Instead, the best interpretations appear to be site specific and often regional in scale.
The Lagrangian chemistry and transport model ATLAS: simulation and validation of stratospheric chemistry and ozone loss in the winter 1999/2000
Authors: Wohltmann I. , Lehmann R. , Rex M.
Published: June 2010

Abstract. ATLAS is a new global Lagrangian Chemistry and Transport Model (CTM), which includes a stratospheric chemistry scheme with 46 active species, 171 reactions, heterogeneous chemistry on polar stratospheric clouds and a Lagrangian denitrification module. Lagrangian (trajectory-based) models have several important advantages over conventional Eulerian models, including the absence of spurious numerical diffusion, efficient code parallelization and no limitation of the largest time step by the Courant-Friedrichs-Lewy criterion. This work describes and validates the stratospheric chemistry scheme of the model. Stratospheric chemistry is simulated with ATLAS for the Arctic winter 1999/2000, with a focus on polar ozone depletion and denitrification. The simulations are used to validate the chemistry module in comparison with measurements of the SOLVE/THESEO 2000 campaign. A Lagrangian denitrification module, which is based on the simulation of the nucleation, sedimentation and growth of a large number of polar stratospheric cloud particles, is used to model the substantial denitrification that occured in this winter.
Performance based design of reinforced concrete beams under impact
Authors: Tachibana S. , Masuya H. , Nakamura S.
Published: June 2010

Abstract. The purpose of this research is to collect fundamental data and to establish a performance-based design method for reinforced concrete beams under perpendicular impact load. Series of low speed impact experiments using reinforced concrete beams were performed varying span length, cross section and main reinforcement. The experimental results are evaluated focusing on the impact load characteristics and the impact behaviours of reinforced concrete beams. Various characteristic values and their relationships are investigated such as the collision energy, the impact force duration, the energy absorbed by the beams and the beam response values. Also the bending performance of the reinforced concrete beams against perpendicular impact is evaluated. An equation is proposed to estimate the maximum displacement of the beam based on the collision energy and the static ultimate bending strength. The validity of the proposed equation is confirmed by comparison with experimental results obtained by other researchers as well as numerical results obtained by FEM simulations. The proposed equation allows for a performance based design of the structure accounting for the actual deformation due to the expected impact action.
Preface "Nonlinear processes in oceanic and atmospheric flows"
Authors: Mancho A. M. , Wiggins S. , Turiel A. , Hernández-García E. , López C. , García-Ladona E.
Published: May 2010

Abstract. Nonlinear phenomena are essential ingredients in many oceanic and atmospheric processes, and successful understanding of them benefits from multidisciplinary collaboration between oceanographers, meteorologists, physicists and mathematicians. The present Special Issue on "Nonlinear Processes in Oceanic and Atmospheric Flows" contains selected contributions from attendants to the workshop which, in the above spirit, was held in Castro Urdiales, Spain, in July 2008. Here we summarize the Special Issue contributions, which include papers on the characterization of ocean transport in the Lagrangian and in the Eulerian frameworks, generation and variability of jets and waves, interactions of fluid flow with plankton dynamics or heavy drops, scaling in meteorological fields, and statistical properties of El Niño Southern Oscillation.
Influence of addition of oat and lentil on the content of the detected components in bread
Authors: Bojňanská Tatiana , Vollmannová Alena , Frančáková Helena
Published: May 2010

In this paper, the results obtained by bread products analysis made with the addition of oats and lentils, which increased its nutrition value are presented. Breads were prepared with addition of 10 %, 20 %, 30 %, 40 % and 50 % which were analyzed for Fe, Mn, Zn, Cu, Co, Ni, Cr, Pb and Cd content. Prepared products were evaluated also from viewpoint of their technological and nutritional value. Use of oat in bread increased with the addition of a quantity of 50 % content of nutritionally significant elements such as Fe (3.2 times), Mn (3.13 times), Zn (2.23 times), Cu (2.01 times) and Cr (1.2 times). The addition of lentils increased particularly Cu content (3.55 times), Zn (2.96 times) and Mn (1.29 times). None of the samples showed exceeded maximum limit (1.0 mg.kg-1) for lead. Based on the analysis results it was confirmed, that the most problematic element in our soils and subsequently in the foodstuffs is cadmium. Exceeded values (< 0.1 mg.kg-1) were detected in 8 samples from 11, in finished products the values were within the limits ranging from 0.090 mg.kg-1 Cd to 0.180 mg.kg-1 Cd.
Prevalence of Staphylococcus aureus in fish processing factory
Authors: Grigoryan Karine , Badalyan Grigor , Andriasyan Djulietta
Published: May 2010

The aim of the presented work was the risk assessment of distribution and prevalence of Staphylococcus aureus during processing of cold-smoked fish. There were totally analyzed 80 samples of fish and 50 swab samples at all stages of the processing. Staphylococcus aureus was detected in 74% of analyzed samples. Brining stage was the important critical control point in cold-smoked fish proceesing.
The influence of propolis application to meat utility on ROSS 308 broiler chickens
Authors: Haščí­k Peter , Melich Martin , Kačániová Miroslava , Pál Gabriel , Mihok Michal , Čuboň Juraj , Melen Martin , Vavrišinová Klára
Published: May 2010

The aim of the experiment was to monitor the impact of propolis extract (experimental group) for meat utility of the Ross 308 chicken. The dosage of propolis was 0.2 g.kg KKZ-1 throught the fattening (40 days). Application of propolis increased (P≤0.01) slaughter weight (+76.80 g) and carcass weight (+67.90 g) in hens compared to the control group (1790.60 g, resp. 1266.54 g). In group with roosters slaughter weight (+70.80 g) and carcass weight (+56.00 g) were also increased (P≥0.05) in the experimental group compared to control (2086.20 g, resp. 1475.20 g). Offal weight in both sexes was lower (P≥0.05) in the experimental group (135.55 g - ♀, 158.21 g - ♂) compared to control (140.75 g - ♀, 168.55 g - ♂). Carcass yield was higher in hens (P≥0.05) in the experimental group (78.71 %) versus control (78.60 %).The evaluation of meat utility Ross 308 chickens  without distinction of sex did not show significant differences (P≥0.05), but a slight increase in slaughter weight and in the carcass weight in group with application of propolis extract in their fattening. Contrary slightly lower offal weight (-7.77 g) and carcass yield (-0.21 %) were found in the experimental group of chickens without distinction of sex (P≥0.05) compared to control group (weight of offal - 154.65 g, carcass yield - 78.69 %). We recommend the application of propolis as a possible supplement in the fattening of chickens, as it increases the performance parameters of meat and may also positively affect the economy of production.