Early Springtime Research Articles

Novel species interactions: American black bears respond to Pacific herring spawn.

BackgroundIn addition to the decline and extinction of the world’s species, the decline and eventual loss of species interactions is one of the major consequences of the biodiversity crisis. On the Pacific coast of North America, diminished runs of salmon (Oncorhynchus spp.) drive numerous marine–terrestrial interactions, many of which have been intensively studied, but marine–terrestrial interactions driven by other species remain relatively unknown. Bears (Ursus spp.) are major vectors of salmon into terrestrial ecosystems, but their participation in other cross-ecosystem interactions is similarly poorly described. Pacific herring (Clupea pallasii), a migratory forage fish in coastal marine ecosystems of the North Pacific Ocean and the dominant forage fish in British Columbia (BC), spawn in nearshore subtidal and intertidal zones. Spawn resources (eggs, milt, and spawning adults) at these events are available to coastal predators and scavengers, including terrestrial species. In this study, we investigated the interaction between American black bears (Ursus americanus) and Pacific herring at spawn events in Quatsino Sound, BC, Canada.ResultsUsing remote cameras to monitor bear activity (1,467 camera days, 29 sites, years 2010–2012) in supratidal and intertidal zones and a machine learning approach, we determined that the quantity of Pacific herring eggs in supratidal and intertidal zones was a leading predictor of black bear activity, with bears positively responding to increasing herring egg masses. Other important predictors included day of the year and Talitrid amphipod (Traskorchestia spp.) mass. A complementary analysis of black bear scats indicated that Pacific herring egg mass was the highest ranked predictor of egg consumption by bears. Pacific herring eggs constituted a substantial yet variable component of the early springtime diet of black bears in Quatsino Sound (frequency of occurrence 0–34%; estimated dietary content 0–63%). Other major dietary items included graminoids (grasses and sedges), Phaeophyta (brown algae), Zosteraceae (seagrasses), and Talitrid amphipods.ConclusionThis research represents the first scientific evidence of a cross-ecosystem interaction between Pacific herring and American black bears. Our findings also expand knowledge of the ecological roles of both species. Combined, evidence of anthropogenic constraints on both black bears and Pacific herring suggests that bear-herring interactions were potentially stronger and more widespread in the past.

On the use of Very Low Frequency transmitter data for remote sensing of atmospheric gravity and planetary waves

Continuous ground-based monitoring of Very Low Frequency (VLF) transmitter signals is an efficient remote sensing tool for studying of the lower ionosphere (60–90km). Here, we present the use of VLF radio data to study short-period (∼min–hrs) atmospheric gravity waves and long-period (∼days) planetary waves. We analyse VLF data from several receiving stations obtained by ICSP-VLF network during the total solar eclipse of July, 2009 to show the existence of short-period atmospheric gravity waves. We find dominant wave periods range from 10min to 1h around the time of maximum eclipse phase which could be associated with atmospheric gravity waves excited due to the eclipse. We also analyse VLF amplitude data of 2007 received at ICSP, Kolkata from VTX (18.2kHz) transmitter for planetary wave-type oscillations in the mesosphere–lower ionosphere system. Fourier and wavelet analysis show presence of periodic structures with periodicity in the range of 5–27days. We compare VLF planetary spectrum with spectrum obtained from total column density of Ozone and mesospheric average temperature data which may indicate vertical coupling between the stratosphere and ionosphere in winter to early spring time.

Shifted migration of the rape stem weevil Ceutorhynchus napi (Coleoptera: Curculionidae) linked to climate change

A multi-model ensemble of 15 climate change projections from regional climate models was used to assess the impact of changes in air temperature and precipitation on the phenology of pest species in agriculture. This allowed the bandwidths of expected changes in both meteorological variables to be calculated, forming the basis for assessing and clearly communicating the uncertainties related to the model results. More specifically, we investigated the potential impact of regional climate change effects on the crop inva- sion of the rape stem weevil, Ceutorhynchus napi Gyllenhal (Coleoptera: Curculionidae), in Central Europe (Luxembourg). Multisite and perennial data from field observations were used to choose a biological model from the literature, based on daily maximum air temperature and daily totals of precipitation to describe the migration of C. napi. Based on this statistical relation, we were able to reproduce the observed crop invasion with a mean root mean squared error (RMSE) of 10 days. Daily values of projected maximum air temperatures and daily totals of precipitation of the multi-model ensemble were used as input data for the threshold-based biologi - cal model that projects the immigration of this pest species into oilseed rape crops (Brassica napus L.). We examined three thirty-year timespans, the near (2021 to 2050) and the far future (2069 to 2098) and compared them to a reference timespan (1961 to 1990). The projections showed a significant shift of crop invasion to an earlier onset for the near (14 days) and far future (21 days) compared to the reference period. In addition, the timespan in which the potential crop invasion will take place increased from 53 days in the reference timespan to 73 days in the near and 65 days in the far future based on the ensemble median values. It could be expected that a shifting of the immigration period will increase the risk of missing the appropriate time frame for an insecticide application. A depletion of stored nutrient resources, leading to starvation after diapause, can be eliminated for C. napi under climate change effects, as this species hibernates motionless as an adult in earth cocoons until emergence in early springtime driven by temperature.

枕崎沖の大陸棚地形に捕捉されて増幅する気象津波の現地観測

Meteotsunamis have frequently been excited in bays and harbors along west coast of Kyushu during early spring time. Makurazaki harbor has also been suffered by meteotsunami disturbances, although its mouth does not open east wards. The present study investigates the possibility of a resonant coupling between atmospheric disturbance and geometric edge waves trapped on the continental shelf. A field observation was conducted by deploying three tidal gauges along the coast. The measured predominant spectral peaks and phase patterns were discussed by referring the theoretically predicted ones for the trapped waves on the shelf.

Sea ice dynamics influence halogen deposition to Svalbard

Abstract. Sea ice is an important parameter in the climate system and its changes impact upon the polar albedo and atmospheric and oceanic circulation. Iodine (I) and bromine (Br) have been measured in a shallow firn core drilled at the summit of the Holtedahlfonna glacier (Northwest Spitsbergen, Svalbard). Changing I concentrations can be linked to the March–May maximum sea ice extension. Bromine enrichment, indexed to the Br / Na sea water mass ratio, appears to be influenced by changes in the seasonal sea ice area. I is emitted from marine biota and so the retreat of March–May sea ice coincides with enlargement of the open-ocean surface which enhances marine primary production and consequent I emission. The observed Br enrichment could be explained by greater Br emissions during the Br explosions that have been observed to occur mainly above first year sea ice during the early springtime. In this work we present the first comparison between halogens in surface snow and Arctic sea ice extension. Although further investigation is required to characterize potential depositional and post-depositional processes, these preliminary findings suggest that I and Br can be linked to variability in the spring maximum sea ice extension and seasonal sea ice surface area.

Abstract 430: Blood Pressure Monitoring in the Biological Time Structures and in Pre- /Post-Surgery Seasonal Variations

Biological time structures (clock-hour), including yearly rhythm (circannual), ~weekly (circaseptan) and circadian are considered essential parameters in blood pressure (BP) to recognize and treat any risk elevation as well as overt disease. BP and heart rate (HR) in adolescents and adults were monitored automatically around the clock at 30-minute to hourly intervals for seasons and/or years. Data was analyzed by the linear least square rhythmometry. All showed significant circadian fluctuations in BP and HR. BP was about 10-20 mm Hg higher in the adult group while HR was lowered in average about 10 beats/min. The circadian response peaked in the noon to the late afternoon hours: SBP: 18:08; DBP: 17:08; HR: 17:40 with the impression from the 5 adult subjects, individual differences notwithstanding, while one teen showed shift changes to the early morning hours: SBP: 01:48; DBP: 01:24: HR: 00:12. Circannual BP and HR revealed significant rhythms with peaks on October 27 (SBP), November 26 (DBP) and October 31 (HR). While the winter month BP and HR were the lowest in comparison to the other 3 seasons, further sudden drops of both BP and HR were noted in the individual at the point of surgery in mid-January. However, when the surgery performed in the same individual in November, the drop was minimal, while early spring time surgery increased SBP significantly with a minimal increase in DBP and HR. Sharp increased double amplitudes (Amps) (SBP 73; DBP 35; HR 24, all P<0.0001) observed in the winter season. The circaseptan double Amps in the adolescent were 13 ± 4 (P=0.019) for SBP and 8 ± 3 mm Hg (P=0.030) for DBP, with acrophases occurring on late Sunday, early Monday (at -50° and -67° from 00:00 on Saturday to Sunday for SBP and DBP, respectively, with 360° ≡ 1 week). Post-OP Amps were significantly shallow compared with control: SBP: 45 vs. 19; DBP: 21 vs. 6; HR: 21 vs. 12 mm Hg, while acrophase (peak hrs) was various: pre-/post-op SBP: 16:44 vs. 11:32; DBP: 11:44 vs. 01:16; HR: 11:44 vs. 13:08 hrs. The increased or shallow Amp can be a predictable risk factor of CVD. Circaseptan acrophases coincide with the time of increased vascular morbidity/mortality in our studies. Chronomes broader than circadian should be considered in interpreting BP responses as a gauge of vascular disease status.

Seasonally active slipface avalanches in the north polar sand sea of Mars: Evidence for a wind‐related origin

Meter‐scale MRO/HiRISE camera images of dune slipfaces in the north polar sand sea of Mars reveal the presence of deep alcoves above depositional fans. These features are apparently active under current climatic conditions, because they form between observations taken in subsequent Mars years. Recently, other workers have hypothesized that the alcoves form due to destabilization and mass‐wasting during sublimation of CO2 frost in the spring. While there is evidence for springtime modification of these features, our analysis of early springtime images reveals that over 80% of the new alcoves are visible underneath the CO2 frost. Thus, we present an alternative hypothesis that formation of new alcoves and fans occurs prior to CO2deposition. We propose that fans and alcoves form primarily by aeolian processes in the mid‐ to late summer, through a sequence of aeolian deposition on the slipface, over‐steepening, failure, and dry granular flow. An aeolian origin is supported by the orientations of the alcoves, which are consistent with recent wind directions. Furthermore, morphologically similar but much smaller alcoves form on terrestrial dune slipfaces, and the size differences between the terrestrial and Martian features may reflect cohesion in the near‐subsurface of the Martian features. The size and preservation of the largest alcoves on the Martian slipfaces also support the presence of an indurated surface layer; thus, new alcoves might be sites of early spring CO2sublimation and secondary mass‐wasting because they act as a window to looser, less indurated materials that warm up more quickly in the spring.

Evolution of south seasonal cap during Martian spring: Insights from high-resolution observations by HiRISE and CRISM on Mars Reconnaissance Orbiter

[1] We use data from the High Resolution Imaging Science Experiment (HiRISE) camera and the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) imaging spectrometer onboard the Mars Reconnaissance Orbiter to follow the evolution of the appearance and composition of 12 regions of the south polar layered deposits from spring to summer time. We distinguish three steps in the evolution of the volatile layer: a decrease of both CO2 band strength and albedo until Ls = 190°–210°, a significant increase in both until Ls = 240°–260° and finally a rapid decrease until the complete defrosting of the ground. In contrast, the water ice band displays a more monotonic decrease. Analysis of HiRISE color images acquired simultaneously with CRISM data allows a plausible interpretation of this evolution. In early springtime (Ls < 200°), intense jet activity results in deposition of fans of large mineral grains and a wide spatial distribution of fine grains. The small-scale topography controls the presence and location of the jets by allowing more solar energy to be collected on slopes. Grains from the dust fans warm and sink through the CO2 layer, resulting in a bluish color at the locations of the fans around Ls = 190°–210°. As the atmosphere warms up, the surface of the ice layer sublimes and releases dust and water, resulting in its brightening. The last phase of the process consists in a progressive defrosting resulting in a patchwork of frozen and unfrozen areas.

Pollution Level and Distribution of PCDD/PCDF Congeners between Gas Phase and Particulate Phase in early Spring Air of Dalian, China

Ambient air of Dalian was sampled with active high-volume air samplers in early spring time. The concentrations and the congeners between gas phase and particulate phase of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) in the air were measured. Samples analysis results showed that the concentration of PCDD/Fs in particulate phase was higher than that in gas phase. The ratio of PCDD to PCDF in gaseous phase and particulate phase was lower than 0.4. The main sources of atmospheric PCDD/Fs in Dalian early spring season were coal-related source. The total I-TEQ in gaseous phase and particulate phase was 30.3 and 143.6 fg m-3, respectively. The I-TEQ of Dalian early spring atmosphere was lower than international standard, the atmospheric quality in Dalian was better.

Storm-clouds brooding on towering heights

Springtime on Saturn came in with a bang last December, when a massive storm erupted in its north temperate zone. This rare event has been observed in unprecedented detail from the ground and from space. See Letters p.71 & p.75 Six Great White Spot (GWS) events have been observed in the atmosphere of Saturn since 1876. These giant convective storms occur roughly once every Saturnian year (equal to 29.5 Earth years). The sixth GWS erupted in December 2010 and has been the subject of intense observation. Two papers in this issue present the details of some of these observations. Sanchez-Lavega et al. report that the storm developed at northern latitudes in the peak of a weak westward jet during early northern springtime. The storm head moved faster than the jet and triggered a disturbance that circled the planet. Numerical simulations show that Saturn's winds extend without decay deep down into the weather layer. Fischer et al. report that the storm reached a width of 10,000 kilometres within three weeks. Its lightning flash rates are an order of magnitude greater than those seen in previous storms, peaking at more than 10 flashes per second.

Spatial variability and temporal dynamics of surface water pCO 2, ΔO 2/Ar and dimethylsulfide in the Ross Sea, Antarctica

We report results from two surveys of pCO 2, biological O 2 saturation (ΔO 2/Ar) and dimethylsulfide (DMS) in surface waters of the Ross Sea polynya. Measurements were made during early spring (November 2006–December 2006) and mid-summer (December 2005–January 2006) using ship-board membrane inlet mass spectrometry (MIMS) for high spatial resolution ( i.e. sub-km) analysis. During the early spring survey, the polynya was in the initial stages of development and exhibited a rapid increase in open water area and phytoplankton biomass over the course of our ∼3 week occupation. We observed a rapid transition from a net heterotrophic ice-covered system (supersaturated pCO 2 and undersaturated O 2) to a high productivity regime associated with a Phaeocystis-dominated phytoplankton bloom. The timing of the early spring phytoplankton bloom was closely tied to increasing sea surface temperature across the polynya, as well as reduced wind speeds and ice cover, leading to enhanced vertical stratification. There was a strong correlation between pCO 2, ΔO 2/Ar, DMS and chlorophyll a (Chl a) during the spring phytoplankton bloom, indicating a strong biological imprint on gas distributions. Box model calculations suggest that pCO 2 drawdown was largely attributable to net community production, while gas exchange and shoaling mixed layers also exerted a strong control on the re-equilibration of mixed layer Ο 2 with the overlying atmosphere. DMS concentrations were closely coupled to Phaeocystis biomass across the early spring polynya, with maximum concentrations exceeding 100 nM. During the summer cruise, we sampled a large net autotrophic polynya, shortly after the seasonal peak in phytoplankton productivity. Both diatoms and Phaeocystis were abundant in the phytoplankton assemblages during this time. Minimum pCO 2 was less than 100 ppm, while ΔO 2/Ar exceeded 30% in some regions. Mean DMS concentrations were ∼2-fold lower than during the spring, although the range of concentrations was similar between the two surveys. There was a significant correlation between pCO 2, ΔO 2/Ar and Chl a across the summer polynya, but the strength of these correlations and the slope of O 2 vs. CO 2 relationship were significantly lower than during the early spring. Summertime DMS concentrations were not significantly correlated to phytoplankton biomass (Chl a), pCO 2 or ΔO 2/Ar. In contrast to the early spring time, there were no clear temporal trends in summertime gas concentrations. Rather, small-scale spatial variability, likely resulting from mixing and localized sea-ice melt, was clearly evident in surface gas distributions across the polynya. Analysis of length-scale dependent variability demonstrated that much of the spatial variance in surface water gases occurred at scales of <20 km, suggesting that high resolution analysis is needed to fully capture biogeochemical heterogeneity in this system.

Waterfowl population survey of the Marcali reservoir (2007–2008)

This study has shown that the Marcali reservoir is an important waterbird wetland habitat especially during the migration period. Based on our findings early springtime season proved to be the most important season concerning bird activities on the reservoir. The reservoir and its surroundings are not specifically important as breeding areas; although, some strictly protected species can be found among the breeding species. It is noteworthy to mention the strong disturbance (waterfolw hunting, intensive fishing, poaching) in the area that can have a negative impact on the breeding success of bird species. The results of similarity measures showed remarkable differences between the bird communities of different seasons. Waterbird communities of the spring season and summer season showed the highest similarity, since part of the species observed during the spring surveys were most probably breeding species that remained in the reservoir area for the summer. Comparison based on bird species diversity showed significant differences between communities of the different seasons. Diversity was higher both in the breeding and the migration season compared with the winter period characterized by the lowest species richness and number of individuals. Water level has proved to be an important determining factor of waterbird species richness.

Modelling Nitrate Formation and Movement in Vineyard Soils – A Contribution to a More Sustainable Viticulture

Ecologically sound production is a catchword used in nearly all viticulture production areas. Besides the pesticides inputs which are unavoidable specific attention is directed to nitrates which can pollute ground water reserves and may have some adverse effects to humans after consumption. There are two main sources for nitrate in vineyard soils: a) mineralization of humic compounds from the soil and b) nitrogen fertilization. In the latter case the inputs can be controlled via balance sheets, which are obligatory in Germany for instance. During a six years period the mineralization process of slowly decomposable organic matter in vineyard soils was evaluated. &#x0D; As a basis STANFORDs equations were used to describe that process but could finally reduced to a zero order equation. These findings were combined with different sub-models from soil science: heat transfer and water movement. Input values are very simple to determine: global irradiation, soil texture (sand, silt, clay) and wet digested organic matter (WALKLEY-BLACK). The compiled model is deterministic. Therefore it is transferable to other, unknown sites. The nitrate dynamic in soils can be followed up with one starting value which under German conditions is determined after harvest or in early springtime: the calculation includes the soils water content, the nitrate concentrations, possibly nitrate losses, and the NO3-content at the point of planned fertilization. Normally the mineral fertilizer input can be reduced without endangering yield and quality of grapevines. The model is now used as a tool for the extension service. On the other hand it is a powerful proof that viticulture, which is mostly carried out in vulnerable land sites, can save the environment for future generations.

고로쇠나무 수액의 출수에 미치는 영향 인자 분석 : (II) 함양 지역

본 연구는 경상남도 함양군 지리산의 고로쇠나무 수액의 출수와 영향 인자들을 분석하여 최적의 출수 조건을 얻는데 기여하고자, 출수량과 시험지의 기온 및 상대습도, 흉고직경 그리고 수액내 당 함량 사이의 상관성을 분석하였다. 고로쇠나무의 흉고직경에 비례하는 출수량과의 상관성은 출수량이 많은 날에 높았고 출수 일수와 시기는 공시목 사이에 큰 차이점이 없었다. 출수량이 높았던 날들의 기온은 일평균기온 <TEX>$1.2{\pm}1.6^{\circ}C$</TEX>, 일최저기온 <TEX>$-4.3{\pm}1.5^{\circ}C$</TEX> 그리고 일최고기온 <TEX>$11.8{\pm}1.9^{\circ}C$</TEX>로 나타났다. 수액 출수는 기온이 영하의 온도를 지속하거나 영상의 온도를 지속할 경우에는 관찰되지 아니하였다. 기온과 출수량과의 상관 분석에서 일최고기온과 일평균기온이 유의적(p < 0.05)으로 관련성이 있는 것으로 나타났다. 수액의 출수 기간 동안 자당의 농도는 일정 수준을 유지 하였으나 출수가 종료되는 시점에서 급격하게 감소하였다. This study was carried out to investigate the optimum condition for sap exudation of Acer mono Max. tree in a site of Mt. Jiri, Hamyang-gun, Korea. Amount of sap exudation, air temperature, relative air humidity, tree diameter at breast height (DBH) and sugar content in sap were monitored during the early springtime, and correlation analysis of several factors was carried out to explain tree-to-tree and date-to-date variations in sap exudation. The correlation, linearlyassociated between DBH and sap amount, was strengthened as daily amount of sap increased, but there was no significant tree-to-tree variation in time and period for sap exudation. When amount of sap exudation was above 10 liter/day, the mean air-temperature was averaged at <TEX>$1.2{\pm}1.6^{\circ}C$</TEX>, the minimum at <TEX>$-4.3{\pm}1.5^{\circ}C$</TEX> and the maximum at <TEX>$11.8{\pm}1.9^{\circ}C$</TEX>. The maximum air temperature and mean air temperature were significant (p < 0.05) factors for amount of sap in correlation analysis to explain date-to-date variation in sap exudation. Sucrose content in sap was in the range of 1.5 and 1.7% during exudation days, but sharply reduced to 0.6% level at the end of exudation period.

INORGANIC CARBON UTILIZATION BY ROSS SEA PHYTOPLANKTON ACROSS NATURAL AND EXPERIMENTAL CO2 GRADIENTS1

We present results from a field study of inorganic carbon (C) acquisition by Ross Sea phytoplankton during Phaeocystis‐dominated early season blooms. Isotope disequilibrium experiments revealed that HCO3− was the primary inorganic C source for photosynthesis in all phytoplankton assemblages. From these experiments, we also derived relative enhancement factors for HCO3−/CO2 interconversion as a measure of extracellular carbonic anhydrase activity (eCA). The enhancement factors ranged from 1.0 (no apparent eCA activity) to 6.4, with an overall mean of 2.9. Additional eCA measurements, made using membrane inlet mass spectrometry (MIMS), yielded activities ranging from 2.4 to 6.9 U · [μg chl a]−1 (mean 4.1). Measurements of short‐term C‐fixation parameters revealed saturation kinetics with respect to external inorganic carbon, with a mean half‐saturation constant for inorganic carbon uptake (K1/2) of ∼380 μM. Comparison of our early springtime results with published data from late‐season Ross Sea assemblages showed that neither HCO3− utilization nor eCA activity was significantly correlated to ambient CO2 levels or phytoplankton taxonomic composition. We did, however, observe a strong negative relationship between surface water pCO2 and short‐term 14C‐fixation rates for the early season survey. Direct incubation experiments showed no statistically significant effects of pCO2 (10 to 80 Pa) on relative HCO3− utilization or eCA activity. Our results provide insight into the seasonal regulation of C uptake by Ross Sea phytoplankton across a range of pCO2 and phytoplankton taxonomic composition.

Treeline vegetation composition and change in Canada's western Subarctic from AVHRR and canopy reflectance modeling

Abstract Climate change is expected to have significant impacts on northern vegetation, particularly along transition zones such as the treeline. Studies of vegetation composition and change in this ecotone have largely focussed on local analysis of individual trees using labour intensive stand reconstruction techniques, which are spatially limited and do not consider vegetation types other than trees. Remote sensing may be well suited to monitoring recent changes across the treeline because it captures integrated changes of all vegetation life forms over large spatial extents. This research examines treeline vegetation composition and change along the western subarctic treeline mapped by Timoney et al. (1992) using a 1 km resolution, 22-year AVHRR archive from 1985–2006. While most remote sensing studies on vegetation change in arctic and subarctic regions only exploit information contained in the Normalized Difference Vegetation Index (NDVI), we examine long-term reflectance trends in AVHRR bands 1 and 2 in addition to NDVI. The GeoSail canopy reflectance model is used to map treeline composition by combining information from 22-year summertime and early springtime composite images. A set of spectral change vectors are then generated from GeoSail simulations and used to classify trends in AVHRR along the treeline to estimate vegetation change. Evaluation of vegetation composition against the MODIS Vegetation Continuous Fields (VCF) product that has been recently validated along the treeline reveals good spatial correspondence. Temporal trends are shown to agree with literature on tundra–taiga vegetation dynamics in recent decades. Evidence is presented that suggests replacement of bare surfaces with herb, conifer decline along the southern treeline, increased shrubiness, and increased conifer recruitment and growth in the north.

Fog characteristics at the airport of Thessaloniki, Greece

Abstract. A statistical approach in order to study fog event characteristics occuring at the airport of Thessaloniki, Northern Greece is presented in this work. To achieve this, the seasonal and diurnal characteristics of fog are investigated using 35 years (1971–2005) of observations of meteorological parameters such as: visibility, air temperature, dew point temperature, air relative humidity, wind vector, precipitation, and cloud base height and coverage. Hourly surface observations of fifteen (15) years (1991–2005) are used to identify fog events induced by various physical mechanisms. Fog events are classified into fog types through the application of objective criteria that are derived upon fog formation processes and under the influence of various physiographic features. The temporal variability of different fog type occurrences are examined and the events are characterized according to their duration and intensity. The results are somehow affected by regional and local factors. Fog is mainly formed in winter time (~64%) with an enhanced likelihood to appear also in late autumn (19%). The highest frequency of the fog events occurs around sunrise or 1 to 2 h before of it. The mean duration of the events is about 4.5 h. Most of them (75%) are dense (visibility &lt;400 m). The overall fog phenomenon is a combination of various types, such as: advection fog, radiation fog, cloud-base lowering fog and precipitation fog. Advection fog (30%) and radiation fog (29%), which are the most common types, occur predominantly in winter and early spring time. With respect to the former type, it seems that, in many cases, already formed fog is advected from the nearby Anthemountas valley. Moreover, a considerable number of fog events (22%) result from cloud-base lowering, and they frequently occur in late autumn and mid winter.

Leaf litter degradation in the wave impact zone of a pre-alpine lake

Contrary to streams, decomposition processes of terrestrial leaf litter are still poorly understood in lakes. Here, we examined the decomposition of two leaf species, beech (Fagus sylvatica) and poplar (Populus nigra ‘italica’) in the littoral zone of a large pre-alpine lake at a wave exposed site. We focussed on the shredding impact of benthic invertebrates in a field experiment and on the effects of wave-induced disturbances under field and mesocosm conditions. In contrast to our expectations, benthic shredders did not reveal an important role in leaf processing under the conditions of the field experiment (early spring time, wave impact zone). Strong wave turbulence during storm events significantly reduced leaf mass, FPOM and invertebrate densities at field conditions. Several reasons can explain the low importance of shredders in our field study: (a) phenology of the shredder species, (b) feeding preferences and alternative food sources for gammarids, (c) generally low abundance of the native gammarid species due to the recent occurrence of an invasive predator, (d) disturbance of shredder activity due to high wave impact and (e) relatively low food value of the offered leaves. We suggest that leaf litter decomposition in lakes occurs in specific process domains, which largely depend on the hydraulic characteristics and on water-level fluctuations.

Are Cambisols in Alpine Karst Autochthonous or Eolian in Origin?

ABSTRACTThis paper deals with a two-year study of karst soils and eolian dust deposition on the Reiteralpe paleosurface (1600 to 2000 m), Northern Calcareous Alps, Germany. Thirty soil profiles of Cambisols developed on Triassic and Cretaceous limestones are investigated. Dust samples collected periodically on snow cover provide influx rates and a seasonal dust record. Samples of soils, insoluble bedrock residue, and dust are characterized by pedological (e.g. grain size) and mineralogical (e.g. heavy minerals) data.The data indicate that limestone subtypes with varying crack-fillings (ferrous clays) determine the colors and amounts of residue. Both correlate positively with the thickness of reddish Bo-horizons, supporting their autochthonous character. The topsoils, however, show substantial eolian addition (silt, fine sand, mica). In winter, far-traveled red Saharan dust without organic material prevails, carried to the area by strong foehn winds. In early springtime, browner dust (organic rich) is observed which contains periglacial silicate-rich detritus from regional sources such as the Crystalline Austrian Alps.The measured winter dust influx rates are 4.8 cm per 10,000 years (related to 210 winter days). This is more than twice the calculated thickness of Holocene residue accumulation out of limestone weathering (2.3 cm per 10,000 years, related to 210 winter days), which indicates that eolian dust is a major contributor to alpine karst soil development.

Carbonyl sulfide (OCS): Large‐scale distributions over North America during INTEX‐NA and relationship to CO2

An extensive set of carbonyl sulfide (OCS) observations were made as part of the NASA Intercontinental Chemical Transport Experiment–North America (INTEX‐NA) study, flown from 1 July to 14 August 2004 mostly over the eastern United States and Canada. These data show that summertime OCS mixing ratios at low altitude were dominated by surface drawdown and were highly correlated with CO2. Although local plumes were observed on some low‐altitude flight legs, anthropogenic OCS sources were small compared to this sink. These INTEX‐NA observations were in marked contrast to the early springtime 2001 Transport and Chemical Evolution over the Pacific experiment, which sampled Asian outflow dominated by anthropogenic OCS emissions. To test the gridded OCS fluxes used in past models, the INTEX‐NA observations were combined with the sulfur transport Eulerian model (STEM) regional atmospheric chemistry model for a top‐down assessment of bottom‐up OCS surface fluxes for North America. Initial STEM results suggest that the modeled fluxes underestimate the OCS plant sink by more than 200%.