Border Ranges Research Articles

It is worth checking old data – validation of Asplenium onopteris L. presence in the most northeastern sites in Europe (Sudetes, SW Poland)

In Poland, isolated serpentine rocks are exclusive habitats of some <em>Asplenium</em> species, reaching here their north or northeastern border range. One of them was <em>Asplenium onopteris</em>, a diploid European species native to Mediterranean and Atlantic areas. Since the nineteenth century, Polish out-of-range sites of <em>A. onopteris</em> have been quoted in literature without critical verification. Thus, to verify occurrence of this species in Poland, we analyzed the nuclear DNA content and micromorphological features as well as critically reviewed the literature data. We proved that all individuals from Polish populations resembling <em>A. onopteris</em> were tetraploids and should be classified as <em>A. adiantum-nigrum</em>. In addition, we validated a taxon <em>silesiacum</em> reported as co-occurring with <em>A. onopteris</em>. The proposed diagnostic features are insufficient to indisputably delimit this taxon, and distinguishing it as a separate unit is not justified. Analyses of the DNA content revealed also the presence of a triploid <em>A. ×centovallense</em>, a new hybrid for Polish flora.

Frequency- and time-domain analysis of a multi-degree-of-freedom point absorber wave energy converter

This study proposes a multi-degree-of-freedom wave energy converter and introduces a 6-PSS (prismatic pair–spherical pair–spherical pair) power take-off mechanism. The frequency- and time-domain dynamic models of a 3-degree of freedom wave energy converter are established. The time-domain model based on frequency-domain data is usually built upon the Cummins equation. The convolution terms in the Cummins equation are substituted by a state-space system by the frequency-domain identification method in this work. The power absorption of the wave energy converter is studied in both regular and irregular waves. It is shown that the advantages with the converter in resonance with waves are evident in regular waves and not so obvious in irregular waves. The appropriate value of power take-off damping terms has relative border range in irregular waves, which can be chosen according to the trends. Through optimization, the total power absorption in the three directions is close to 126 kW. The results indicate tha...

Thermodynamic analyses of the solar-driven Kalina cycle having a variable concentration ratio

Solar thermal power generation is currently an attractive solar electricity technology. Currently, we face an important issue of lower annual solar-to-power efficiency (approximately 10.0%) using parabolic trough technology because the direct normal irradiance instantly varies, and the solar thermal power cycle always derivates from the designed operation. Here, we investigate a middle-temperature solar-driven Kalina cycle that uses a parabolic trough collector with a variable concentration ratio. From lower to higher direct normal irradiance, both the aperture area of collector and the flow process of the Kalina cycle can be changed. As a result, a much border direct normal irradiance of 100–1000W/m2 achieves a solar-to-power efficiency of 4–20%, resulting in an annual solar-to-power efficiency of approximately 14%. Furthermore, the interactions are analyzed among direct normal irradiance, the aperture area of the collector, and the flow process of the thermal cycle. An operation method for off-design conditions is proposed to greatly improve the annual solar-to-power efficiency, offering a pathway to efficiently utilize a border range of direct normal irradiance.

A questão indígena brasileira: Entre Jean-Jacques Rousseau e Auguste Comte

From a population esteemed at 5 to 6 million people in the sixteenth century to hundreds of thousands today, Brazilian indigenous population is confined in what is called Indigenous Landmarks (TI). Despite the numerically small population, this group occupies territories in where several natural resources have been identified and, even though the access to these resources is important for national development, it is being hampered as they are located in those lands. In addition, an large extend of TI is located on the border range, with the existence of an indigenous group occupying territories of two different countries at the same time, what may eventually mean a threat to national sovereignty. Moreover, the identification of foreign interests for Amazonia territories and natural resources in TI, threatens the protection of national interests. As it is ethically illegitimate deny indigenous rights to live according to their ancient customs - which requires land to hunt, collect and move - it is also unrealistic to consider that national development can dispense with access to the natural resources in TI. Thus, it is urgent that the Brazilian government reconsiders the treatment given to the indigenous people issues. A necessary step is to increase the awareness by the main actors involved - Brazilian anthropologists and Armed Forces - about the ideological foundations of the theme, reevaluating them and, when necessary, overcoming them. And these fundaments can be found in Jean-Jacques Rousseau's and Auguste Comte's work.

A questão indígena brasileira: Entre Jean-Jacques Rousseau e Auguste Comte

From a population esteemed at 5 to 6 million people in the sixteenth century to hundreds of thousands today, Brazilian indigenous population is confined in what is called Indigenous Landmarks (TI). Despite the numerically small population, this group occupies territories in where several natural resources have been identified and, even though the access to these resources is important for national development, it is being hampered as they are located in those lands. In addition, an large extend of TI is located on the border range, with the existence of an indigenous group occupying territories of two different countries at the same time, what may eventually mean a threat to national sovereignty. Moreover, the identification of foreign interests for Amazonia territories and natural resources in TI, threatens the protection of national interests. As it is ethically illegitimate deny indigenous rights to live according to their ancient customs - which requires land to hunt, collect and move - it is also unrealistic to consider that national development can dispense with access to the natural resources in TI. Thus, it is urgent that the Brazilian government reconsiders the treatment given to the indigenous people issues. A necessary step is to increase the awareness by the main actors involved - Brazilian anthropologists and Armed Forces - about the ideological foundations of the theme, reevaluating them and, when necessary, overcoming them. And these fundaments can be found in Jean-Jacques Rousseau's and Auguste Comte's work.

Thermochronology in southeast Alaska and southwest Yukon: Implications for North American Plate response to terrane accretion

This study presents the first comprehensive dataset of low-temperature thermochronology from 43 bedrock samples collected north of the active Yakutat–North American plate boundary. Our apatite and zircon (U–Th)/He and fission-track data reveal the cooling history of the inboard Wrangellia Composite Terrane that is dominated by rapid cooling after Late Jurassic to Early Cretaceous arc magmatism followed by very little cooling and exhumation until today. Deformation resulting in rock exhumation due to the collision of the Yakutat microplate is spatially very limited (20–30 km) and is concentrated mainly in the Chugach–Prince William Terrane and rocks near the Border Ranges Fault. Focused exhumation from greater depths of ca. 10 km with very high rates (>5 km/Myr) is localized at the syntaxis region, starting ca. 10 Ma and shifted south through time. The rapid exhumation rates are explained by the development of strong feedbacks between tectonically driven surface uplift and erosion, which started already before glaciation of the area. The shift in the location towards the south is a consequence of continuous readjusting between tectonics and climate, which is changing on local and global scales since the Late Miocene.

The influence of topographic variation on forest structure in two woody plant communities: A remote sensing approach

Aim of study: The study aimed to characterise variation in structural attributes of vegetation in relation to variations in topographic position using LIDAR data over landscapes.Area of study: The study was conducted in open canopy eucalypt-dominated forest (Richmond Range National Park-RRNP) and closed canopy subtropical rainforest (Border Ranges National Park-BRNP) in north-eastern New South Wales, Australia.Material and Methods: one metre resolution digital canopy height model (CHM) was extracted from the LIDAR data and used to estimate maximum overstorey height and crown area. LIDAR fractional cover representing the photosynthetic and non-photosynthetic component of canopy was calculated using LIDAR points aggregated into 50 m spatial bins. Potential solar insolation, Topographic Wetness Index (TWI), slope and the elevation were processed using LIDAR derived digital elevation models.Main results: No relationship was found between maximum overstorey height and insolation gradient in the BRNP. Maximum overstorey height decreased with increasing insolation in the RRNP (R2 0.45). Maximum overstorey height increased with increasing TWI in the RRNP. Average crown area decreased with increasing insolation in both study areas. LIDAR fractional cover decreased with increasing insolation (R2 0.54), and increased with increasing TWI (R2 0.57) in the RRNP.Research highlights: The characterization of structural parameters of vegetation in relation to the variation of the topography was possible in eucalyptus dominated open canopy forest. No reportable difference in variation of structural elements of vegetation was detected with topographic variation of subtropical rainforest.

Notes on the Zoothera thrushes in the Tweed Range of northeastern New South Wales

The Zoothera thrush complex is represented on the Australian mainland by the Bassian Thrush Z. lunulata and the Russet-tailed Thrush Z. heinei. These species are sympatric at several locations on the eastern coast. Often, these populations occupy different elevations, with the Bassian Thrush preferring higher elevations, though reasons for this are poorly understood. I present data from automated acoustic recordings made of these species in the Border Ranges and Mebbin National Parks of north-eastern New South Wales between ~300 m and 1100 m above sea-level over a 1-year period from June 2015 to May 2016. Bassian Thrushes were recorded most frequently in October, typically at or above 900 m. Russet-tailed Thrushes were recorded most frequently in August, at or below 700 m. Differences in elevational preference between the species may be driven by several factors including adaptation to cold, avoidance of interspecific competition and avoidance of hybridisation.

Variation in the Timing of Reproduction and Clutch Size of Afrocanarian Blue TitsCyanistes teneriffae ultramarinusin the Saharan Atlas of Algeria

ABSTRACT We examined the variation in the date of the onset of egg laying and clutch size in three peripheral populations of the Afrocanarian Blue Tits Cyanistes teneriffae ultramarinus at the edge of the species and subspecies geographic range. This study was carried out in three study sites, 130–290 km apart, in similar geographic conditions of the South Border Range of the Saharan Atlas in Algeria. Mean altitudes of nesting territories were between 1327 and 1437 m a.s.l. Habitats of the study sites were covered by the secondary, human-modified vegetation, ranging from a maquis shrubland, with the Holm oak Quercus ilex shrubs to woodlands dominated by the Atlas cedar Cedrus atlantica or by the Aleppo pine Pinus halepensis. 169 wooden nest-boxes were monitored for breeding parameters (laying dates and clutch sizes) during the breeding seasons 2007–2009 and 2011–2013. The timing of egg laying was relatively late for the latitude of the study sites, with overall mean laying dates varying between the study ...

The tectonic significance of the Early Cretaceous forearc-metamorphic assemblage in south-central Alaska based on detrital zircon U–Pb dating of sedimentary protoliths

A complex array of faulted arc rocks and variably metamorphosed forearc accretionary complex rocks form a mappable arc–forearc boundary in southern Alaska known as the Border Ranges fault (BRF). We use detrital U–Pb zircon dating of metasedimentary rocks within the Knik River terrane in the western Chugach Mountains to show that a belt of Early Cretaceous amphibolite-facies metamorphic rocks along the BRF was formed when older mélange rocks of the Chugach accretionary complex were reworked in a sinistral-oblique thrust reactivation of the BRF during a period of forearc plutonism. The metamorphic subterrane of the Knik River terrane has a maximum depositional age (MDA) of 156.5 ± 1.5 Ma and a detrital zircon age spectrum that is indistinguishable from the Potter Creek assemblage of the Chugach accretionary complex, supporting correlation of these units. These ages contrast strongly with new and existing data that show Triassic to earliest Jurassic detrital zircon ages from metamorphic screens in the plutonic subterrane of the Knik River terrane, a fragmented Early Jurassic plutonic assemblage generally interpreted as the basement of the Peninsular terrane. Based on these findings, we propose the following new terminology for the Knik River terrane: (1) “Carpenter Creek metamorphic complex” for the Early Cretaceous “metamorphic subterrane”, (2) “western Chugach trondhjemite suite” for the Early Cretaceous forearc plutons within the belt, (3) “Friday Creek assemblage” for a transitional mélange unit that contains blocks of the Carpenter Creek complex in a chert–argillite matrix, and (4) “Knik River metamorphic complex” in reference to metamorphic rocks engulfed by Early Jurassic plutons of the Peninsular terrane that represent the roots of the Talkeetna arc. The correlation of the Carpenter Creek metamorphic complex with the Chugach mélange indicates that the trace of the BRF lies ∼1–5 km north of the map trace shown on geologic maps, although, like other segments of the BRF, this boundary is blurred by local complexities within the BRF system. Ductile deformation of the mélange is sufficiently intense that few vestiges of its original mélange fabric exist, suggesting the scarcity of rocks described as mélange in the cores of many orogens may result from misidentification of rocks that have been intensely overprinted by younger, ductile deformation.

Mobility, Stasis and Transnational Kin: Western Later-life Migrants in Southeast Asia

Studies of transnational families tend to filter understandings of mobility and stasis through a bi-national framework that juxtaposes the movement of migrants across international borders with the immobility of in-place kin within equally static national spaces. This article examines the concept-metaphors of mobility and stasis through the eyes of later-life (over 50 year-old) Western migrants living in Penang, Malaysia and Bali, Indonesia. By treating “in-place” kin as mobile subjects I examine the extent to which the movement of individuals and families within and across a range of national borders affects the lives, concerns and movements of these older, Western migrants and retirees in Southeast Asia. By examining the concept-metaphors from the perspective of these migrants I illustrate the extent to which such people both succumb to yet exceed scholarly imaginings of im/mobility and juxtapositions between mobile selves and immobile others. Migrant thinking about these concept-metaphors, I suggest, complicates an ongoing tendency within the field of transnational family studies to view mobility and stasis as categorical opposites and offers fresh insights into the role and relevance of these concept-metaphors in the lives of Western migrants in Southeast Asia and their transnational relations with teenage and adult children, ageing parents and grandchildren.

Where did all the trees come from? A novel multispecies approach reveals the impacts of biogeographical history and functional diversity on rain forest assembly

AbstractAimWe take advantage of next generation sequencing‐based technology to assess how landscape‐level dynamics, biogeographical history and functional factors shape the distribution of genetic diversity in rain forest trees. To achieve this, we explore chloroplast genomic diversity and divergence patterns across multiple, co‐distributed species from three major centres of rain forest diversity.LocationSubtropical rain forests in south‐eastern Australia: Nightcap–Border Ranges, Dorrigo and Washpool.MethodsWe assembled chloroplast genomic data from whole‐genome shotgun libraries for 71 species collected across three major centres of rain forest diversity. Chloroplast single nucleotide polymorphisms were used to measure genetic variation within and between multiple populations, species and locations, and we used this information to identify patterns related to landscape‐level processes, biogeographical origins and functional characteristics.ResultsWe identified Nightcap–Border Ranges and Dorrigo as containing multiple refugia and Washpool as primarily a recolonized area. We found that rapidly expanding lineages of Indo‐Malesian origin exhibit significantly lower levels of genetic diversity than Gondwanan lineages with longer local histories. Functional traits related to persistence and dispersal were the most important in regulating the distribution of genetic diversity.Main conclusionsThe distribution and assembly of species reflect interactions and competition between different floristic elements at different stages of continental occupation. Additionally, given the multiple evolutionary origins and histories of the Australian rain forest flora, it is important to avoid treating rain forest communities as single management units.

Moss and vascular epiphyte distributions over host tree and elevation gradients in Australian subtropical rainforest

There is a lack of comprehensive studies on the ecology of epiphytic flora in Australia’s rainforests. Globally, rainforest epiphyte distribution is determined by three main factors: micro-climate within the host tree; landscape changes in macro-climate; and the characteristics of the host tree. We tested the influence of these factors on the species richness and composition of vascular and non-vascular epiphytes in the subtropical rainforest of the Border Ranges in New South Wales. Vascular epiphytes and mosses were recorded in situ from four height zones, with 10 trees sampled at five elevations between 300 and 1100 m above sea level (asl). Vascular epiphyte species richness was highest in the inner canopy (6.3 species), whereas mosses tended to have a uniform distribution over the height zones (3.8–5.0 species). We found that both moss and vascular epiphyte species richness peaked at mid-elevations (500–700 m), with moss richness at a slightly higher elevation than the vascular epiphytes. Host tree characteristics (bark roughness, host size) explained very little of the species composition or richness of epiphytes. Strong patterns in species richness and composition over host tree and elevation gradients suggest that moisture, temperature and light may be the major influences on epiphyte distributions in the Border Ranges.

Population stability in the endangered Fleay’s barred frog (Mixophyes fleayi) and a program for long-term monitoring

In the wake of the global decline in amphibians there is a need for long-term population monitoring. Previous research suggested that the endangered Fleay’s barred frog (Mixophyes fleayi) had recovered after a severe decline. We aimed to determine whether this recovery has been sustained and to test an example of a monitoring program that could be employed at intervals of five or more years to assess long-term population stability. We conducted capture–mark–recapture five years after the last detailed census at Brindle Creek in Border Ranges National Park, New South Wales. Frogs were captured along a 200 m creek transect between September 2013 and February 2014. We used program Mark to estimate demographic parameters of adult male frogs using two modelling approaches: robust design (RD) and the POPAN formulation of the Jolly–Seber model. Abundance was estimated at 38.2 ± 0.5 (s.e.) (RD) and 46.0 ± 2.7 (POPAN). Abundance in 2008 was estimated at 53.2 ± 10.0 (POPAN) male frogs. Estimates of apparent monthly survival over our five-month-long study were very high (RD: 1.0 ± 0.0; POPAN: 1.0 ± 0.02). Recapture estimates were also high (RD: 0.40 ± 0.07 to 0.72 ± 0.05 per session; POPAN: 0.84 ± 0.05 per month). These data suggest that the Brindle Creek population has remained relatively stable over a period of ~10 years.

Altitudinal variation of parasitic Hymenoptera assemblages in Australian subtropical rainforest

Patterns of species assemblages along altitudinal gradients provide insights into ecological patterns and processes. Parasitoids play an important role in ecosystems, yet there are few studies on parasitoid assemblages, partly because of difficulty in identification of parasitoids to species or their surrogates, morphospecies. The aim of this study is to assess differences in assemblages of parasitic Hymenoptera along an altitudinal gradient at both the family and morphospecies level, and the potential of environmental variables for explaining these differences. We sampled from four replicate sites at each of five elevations (approximately 300, 500, 700, 900 and 1100m above sea level (asl)) within continuous subtropical rainforest of the Border Ranges National Park in New South Wales, Australia. At each site, we operated a Malaise trap for 10 days in December 2011 and again in February 2012. Parasitic wasps were sorted to families, and two of the common families (Diapriidae and Ichneumonidae) were further sorted to morphospecies. At both family and morphospecies level, we found gradual altitudinal turnover with a clear separation between upland' (900 and 1100masl) and lowland' (300 and 500masl) assemblages. Unlike parallel studies of some other major taxa, we did not detect distinct assemblages at each altitude at the taxonomic resolution used. In addition, response patterns were different between the two sampling occasions. Changes in assemblage composition were best explained by either altitude or temperature. Although parasitic Hymenoptera do not respond as clearly to changes in altitude as some other taxa, the changes detected here, even at the family level, are important given the role parasitoids play in ecosystem functioning.

Impact of Climate Change on the Distribution ofAedes albopictus(Diptera: Culicidae) in Northern Japan: Retrospective Analyses

The impact of climate change on the distribution of Aedes albopictus (Skuse) was analyzed in northern Japan, where chronological distribution records are incomplete. We analyzed local climate data using linear regression of the thermal suitability index (TSI) for the mosquito and mean annual temperature as functions of time. In northern Japan, thermal conditions since the early 20th century have become increasingly suitable for Ae. albopictus, more as a result of decreasing coldness in the overwintering season than increasing warmth in the reproductive season. Based on recent discovery records of Ae. albopictus in the northern border range, we determined thermal criteria for estimating when its persistent establishment became thermally possible. Retrospective analyses indicated that those criteria were reached in most coastal lowlands of northern Honshu before the accelerated temperature increase after the mid-1980s and the first records of this species after 1990; at some sites, temperature criteria were reached during or before the early 20th century. Expansion of the thermally suitable range after 1990 was supported only for inland areas and the northernmost Pacific coast. The estimated expansion rate was approximately 26 km per decade. Our analyses also demonstrated the importance of local climate heterogeneity (apart from north-south or altitudinal temperature gradients) in determining the expansion pattern.

Metamorphic P–T conditions across the Chugach Metamorphic Complex (Alaska)—A record of focussed exhumation during transpression

The Chugach Metamorphic Complex (CMC) is a large high-grade metamorphic complex that developed in the Eocene within the Chugach accretionary complex along the margin of Alaska where subduction is still ongoing. The CMC has a conspicuous asymmetric structure with a migmatitic zone flanked in the north and west by amphibolite facies schists and in the south by a metabasite belt. To the north and south, major, crustal-scale fault zones juxtapose the Chugach terrane against much lower-grade and less-deformed sequences belonging to different terranes. Curiously these crustal-scale structures are known to have largely strike slip motion posing the question as to the nature of the exhumation of the high-grade complex between them. However, P–T conditions which would allow an estimation of the amount of exhumation were lacking for large parts of the complex. This paper presents petrographic descriptions, biotite–garnet thermometry, RSCM thermometry, average P–T calculations and pseudosection modelling from three major across-strike transects covering the complex from west to south-east. Our results reveal that, both temperature and pressure vary substantially across the complex. More specifically, peak metamorphic conditions evolve from 4–7kbar and ~550–650°C in the northern schist zone to 5–11kbar and ~650–750°C in the migmatite zone in the south of the complex. The higher pressure estimates in the south of the complex indicate that focussed exhumation must have occurred in this area and was probably initiated by the subduction of a high topographic relief (intra-oceanic arc or ridge subduction) and the accretion of the metabasite belt in the south. Exhumation of the CMC occurred in an overall transpressive strain regime, with strike-slip deformation concentrated along the northern Border Range fault zone and thrusting and exhumation focussed within the southern migmatite zone and splay faults of the Contact fault zone. The T/P ratios in the southern migmatite zone indicate that the thermal perturbation of the migmatites is less than previously inferred. These new results, associated with the structural data and the accretion of a metabasite belt in the south of the complex, seem incompatible with the existing ridge-subduction models.

Landscape Patterns in Rainforest Phylogenetic Signal: Isolated Islands of Refugia or Structured Continental Distributions?

ObjectivesIdentify patterns of change in species distributions, diversity, concentrations of evolutionary history, and assembly of Australian rainforests.MethodsWe used the distribution records of all known rainforest woody species in Australia across their full continental extent. These were analysed using measures of species richness, phylogenetic diversity (PD), phylogenetic endemism (PE) and phylogenetic structure (net relatedness index; NRI). Phylogenetic structure was assessed using both continental and regional species pools. To test the influence of growth-form, freestanding and climbing plants were analysed independently, and in combination.ResultsSpecies richness decreased along two generally orthogonal continental axes, corresponding with wet to seasonally dry and tropical to temperate habitats. The PE analyses identified four main areas of substantially restricted phylogenetic diversity, including parts of Cape York, Wet Tropics, Border Ranges, and Tasmania. The continental pool NRI results showed evenness (species less related than expected by chance) in groups of grid cells in coastally aligned areas of species rich tropical and sub-tropical rainforest, and in low diversity moist forest areas in the south-east of the Great Dividing Range and in Tasmania. Monsoon and drier vine forests, and moist forests inland from upland refugia showed phylogenetic clustering, reflecting lower diversity and more relatedness. Signals for evenness in Tasmania and clustering in northern monsoon forests weakened in analyses using regional species pools. For climbing plants, values for NRI by grid cell showed strong spatial structuring, with high diversity and PE concentrated in moist tropical and subtropical regions.Conclusions/SignificanceConcentrations of rainforest evolutionary history (phylo-diversity) were patchily distributed within a continuum of species distributions. Contrasting with previous concepts of rainforest community distribution, our findings of continuous distributions and continental connectivity have significant implications for interpreting rainforest evolutionary history and current day ecological processes, and for managing rainforest diversity in changing circumstances.

Constraints on the Structure of the Border Ranges Fault System, Kenai Peninsula, Alaska from the Preliminary Results of the 3D Inversion Model of Gravity Data

SUMMARY We tested plausible initial 3D density models across the eastern Cook Inlet basin to constrain the geometry of the Border Ranges fault system (BRFS). The BRFS forms the structural boundary between the forearc-arc structures and accretionary terranes of the Aleutian subduction zone in southern Alaska. We used 2D density cross-sections as starting “a priori” models to constrain the 3D inversion model. We computed the theoretical gravity based on the inversion, compared it to the observed gravity, and determined the gravity misfit. We tested the 3D inversion solutions on the lowland regions where the densest spacing of gravity points is located using three surfaces defining the topographic ground level, the top and base of the sediment layers within Cook Inlet basin to build the preliminary 3D models. Preliminary results show the 3D inversion is able to constrain the simple shape of Cook Inlet basin with geologically reasonable densities. We will produce several alternative starting models for the entire Cook Inlet forearc basin and the BRFS. The most reasonable models will be used as starting models for the structure of the entire study area.

Effect of surfactauts on gas hold-up in baffed column reactor

The present work aims to study the performance of Baffled bubble Column Reactoron homogeneous flow regime .Experiments were carried out to investigate the effecta surface active agent (type and concentration ) on Gas Hold-Up in Baffled bubbleColumn Reactor on with the border range of superficial gas velocity (0.001 -0.039m/s). Ethanol and hexanol were used as surfactants in the present work. Also threetypes of baffles: perforated, circular and fin baffle were used. The results show that thegas hold up increases with increasing the concentration of the surfactants. The highestvalues of gas hold up were recorded in the presence of perforated baffle with 30% ofethanol-water and hexanol-water mixture.