Dry Interior Research Articles

A dry interior for Venus suggests the planet was never habitable

A dry interior for Venus suggests the planet was never habitable

Diversity of soils on Kolguev Island with cryometamorphic horizons

Kolguev Island (Barentz Sea, the subzone of typical tundra) was poorly soil surveyed until recently. During expeditionary research 2018–2023, it was revealed that a significant proportion of the soil cover is represented by soils that have horizons with a well-manifested structure, which were diagnosed as cryometamorphic ones. In this regard, the purpose of this work is to characterize the diversity and morphological features of tundra soils with a cryometamorphic horizon identified on the island. The cryometamorphic horizons most often had the specific angular-grainy structure with sharp edges or granular structure with rounded surfaces. The most typical size of aggregates is 1–3 mm; less common – up to 4 mm or less than 1 mm. In some cases, the structure was water-resistant and the soil aggregates had a denser, drier interior. A platy-grained structure with silty-sand coatings was less common. A key feature of the cryometamorphic Kolguev soils is lacking structure in the upper 5–10 cm of the profile. Such soils are the main component of the soil cover. The gleyic subtype of cryometamorphic soils and cryometamorphic gleezems are more often found as components of the soil cover micropatterns. Cryometamorphic soils with a morphologically pronounced spodic horizon were described in one of the central parts of the island. Based on the principles of Soil Classification of Russia, the following types of soils were identified: cryometamorphic, mucky-cryometamorphic, cryometamorphic gleezems; as well as soils, that were tentatively classified as a new type – cryometamorphic podburs and a new subtype – cryometamorphic peaty gleezems. Thus, the study of Kolguev soils showed that the cryometamorphic soils are distributed much extensive than previously assumed.

Fuel types misrepresent forest structure and composition in interior British Columbia: a way forward

BackgroundA clear understanding of the connectivity, structure, and composition of wildland fuels is essential for effective wildfire management. However, fuel typing and mapping are challenging owing to a broad diversity of fuel conditions and their spatial and temporal heterogeneity. In Canada, fuel types and potential fire behavior are characterized using the Fire Behavior Prediction (FBP) System, which uses an association approach to categorize vegetation into 16 fuel types based on stand structure and composition. In British Columbia (BC), provincial and national FBP System fuel type maps are derived from remotely sensed forest inventory data and are widely used for wildfire operations, fuel management, and scientific research. Despite their widespread usage, the accuracy and applicability of these fuel type maps have not been formally assessed. To address this knowledge gap, we quantified the agreement between on-site assessments and provincial and national fuel type maps in interior BC.ResultsWe consistently found poor correspondence between field assessment data and both provincial and national fuel types. Mismatches were particularly frequent for (i) dry interior ecosystems, (ii) mixedwood and deciduous fuel types, and (iii) post-harvesting conditions. For 58% of field plots, there was no suitable match to the extant fuel structure and composition. Mismatches were driven by the accuracy and availability of forest inventory data and low applicability of the Canadian FBP System to interior BC fuels.ConclusionsThe fuel typing mismatches we identified can limit scientific research, but also challenge wildfire operations and fuel management decisions. Improving fuel typing accuracy will require a significant effort in fuel inventory data and system upgrades to adequately represent the diversity of extant fuels. To more effectively link conditions to expected fire behavior outcomes, we recommend a fuel classification approach and emphasis on observed fuels and measured fire behavior data for the systems we seek to represent.

Surviving the heat: multiwavelength analysis of V883 Ori reveals that dust aggregates survive the sublimation of their ice mantles

ABSTRACT Investigating the response of icy dust aggregates to water ice sublimation is essential for understanding the formation and properties of planetesimals in protoplanetary discs. However, their fate remains unclear, as previous studies suggest that aggregates could either survive or completely fall apart to (sub)μm-sized grains. Protoplanetary discs around stars undergoing accretion outbursts represent a unique laboratory to study the ice sublimation process, as the water snowline is pushed outward to regions accessible to current observatories. In this work, we aim to understand the aggregates’ response to ice sublimation by focusing on V883 Ori, a system currently undergoing a powerful accretion outburst. We present new analysis of archival high-resolution ALMA observations of the protoplanetary disc of V883 Ori at 0.88, 1.3, 2.0, and 3.1 mm, and derive new radial spectral index profiles, which we compare with predictions from one-dimensional dust evolution simulations. In the region of V883 Ori where water ice has sublimated, we find lower spectral indices than previously obtained, indicating the presence of cm-sized particles. Coupled with our dust evolution models, we find that the only way to explain their presence is to assume that they formed before the outburst and survived the sublimation process. The resilience of dust aggregates to such intense events leads us to speculate that it may extend to other environments with more gentle heating, such as pebbles drifting through the water snowline in quiescent protoplanetary discs. In that case, it may alter the formation pathway of dry planetesimals interior to the snowline.

First Nations' Prescribed Burning in British Columbia

The Indigenous peoples of British Columbia (BC) have a long and deep tradition of cultural burning. It was an important component of many of BC’s ecosystems until colonial authorities systematically discouraged the practice from the 1870s onwards. Eventually the beneficial role of fire was recognized, particularly in dry interior (NDT 4) ecosystems. To help validate those traditional practices, this article draws on settler and Indigenous accounts of First Nations cultural burning in BC.

Identifying most relevant controls on catchment hydrological similarity using model transferability – A comprehensive study in Iran

A key goal of hydrological science is to understand the climatic controls on catchment hydrological response behavior. Progress toward this goal would result in improved model transferability from gauged to gauged catchments. In this sense, the effectiveness of the model's transferability is contingent on the proper selection of donor and target catchment pairs. Thus, using a rainfall-runoff model, we evaluate two distinct types of hydrological similarity in this study: (i) the apparent similarity measured by similarity distance based on observable catchments descriptors (CDs) and a Euclidean distance based on physical similarity (PS) method and (ii) behavioral similarity, which is determined by highest-performance of transferred model parameters between gauged donor catchment and ungauged target catchment (best-donor case (BD)). It is believed that catchments that apparently to be similar in terms of CDs, have a similar hydrological behavior. We wish to see if that assumption is valid in this paper. Spatial proximity (SP) is also implemented to see if it might be used as an alternative for PS where there is no apparent physical similarity between catchments. To test the study's assumptions, the HBV conceptual rainfall-runoff model is used in 576 catchments across four climate regions in Iran. The results indicate that: (1) as expected, the best-donor (BD) case performs the best, and the more than 75 % of our physically similar catchments have a hydrological similarity (the overlap was ≥ 70 %), (2) the superiority of PS over SP demonstrates that the CDs exert a great influence on transferability within each climate region than geographical distance. However, we demonstrated that the SP is superior, when spatial distance between donor and target catchments is reduced (nearest neighbor ≤ 20 km), (3) consistent with CDs, when utilizing SP method, geographical distance has a varying effect on model transferability within wetter and drier regions, such that SP performs better in wetter regions than it does in dry interior regions, (4) throughout Iran, the dominant controls on model transferability differ by region. Thus, the climatic (aridity index or PET/P), topographic (mean elevation), and physiographic (catchment area) properties exert a greater influence on parameter transfer to ungauged catchments than do other CDs, and (5) the runoff ratio (streamflow signature) confirmed the superiority of the wetter regions over the drier regions in terms of control on the parameters transfer.

Patterns of infestation by subcortical insects (Coleoptera: Buprestidae, Cerambycidae) after widespread wildfires in mature Douglas-fir (Pseudotsuga menziesii) forests

Warming temperatures and changing weather patterns are causing more frequent and severe disturbances in western North American forests. The increasing length and severity of recent wildfire seasons have annually caused widespread injury to millions of trees, facilitating the subsequent outbreak of various subcortical insect species that infest damaged hosts. The subcortical woodboring beetle assemblage (Coleoptera: Cerambycidae and Buprestidae) comprises insects that feed primarily within the phloem and sapwood of defensively compromised trees, often causing severe degradation of high value stands slated for post-fire salvage logging. We studied three 2017 fire complexes within mature Douglas-fir (Pseudotsuga menziesii) forests in southern British Columbia to investigate the post-fire infestation patterns of woodborers. We observed the highest levels of woodborer infestation in forests with moderate to high levels of fire injury, rather than in extremely burnt stands with greater tree mortality. We also found that woodborer infestation likelihood could be predicted from a combination of tree height and fire injury for individual trees. In addition, infestation was more likely in large (>13.1 m tall) rather than small trees (<13 m tall) with the same levels of fire injury. We conclude that the woodboring beetle assemblage present in dry interior Douglas-fir forests is more aggressive and ubiquitous than previously observed, and these insects actively attack and kill living trees that may otherwise survive after fires with both economic and ecological ramifications. Economically, post-fire salvage may be more effective in preventing woodborer population build-up and timber degradation by targeting moderately scorched stands immediately after wildfire. Ecologically, woodborer impacts to trees that would otherwise survive may compromise their biological legacy and impair the diversity and composition of future Douglas-fir stands.

Effect of Differentiated Relative Humidity of Air on the Quality of Traditional Speciality Guaranteed “Krakowska Sucha Staropolska” Sausage

The aim of the study was to determine the effects of air relative humidity (RH: 60 and 80%) during the drying process of “krakowska sucha staropolska” (KSS) sausages on selected quality characteristics. The composition and production process of KSS sausages complied the requirements of traditional specialities guaranteed. It was found that the use of lower RH of drying air allowed a time reduction of 20%. Lowering the RH of air during the drying process did not affect the cross-sectional colour and odour of the sausages, colour components, TBARS values, protein, fat and salt content. However, the acceleration of the drying process resulted in very dried outer layers and less dry interior of KSS sausages. As a result, the sausages had lower scores in the sensory evaluation of hardness and overall acceptability. For this reason, shortening the drying process of sausages by using air with lower relative humidity is not recommended.

Characterisation of degradation of photovoltaic (PV) module technologies in different climatic zones in Ghana

Degradation of photovoltaic (PV) modules depends on technology and environmental conditions. This study characterised the degradation rates of different PV module technologies in three climatic zones in Ghana to determine the technology that would suffice specific environmental conditions in Ghana. The study sampled 104 PV modules of different technologies and ages from 16 PV systems in these climatic zones. The study employed current–voltage (I-V) curve tracing for data collection. The results revealed that the median power degradation rates of monocrystalline silicon modules were least with 0.76%/year and 1.39%/year in Dry Equatorial Climatic Zone and Interior Savannah Climatic Zone respectively, followed by polycrystalline silicon modules with 1.31%/year, 1.35%/year and 1.57%/year in Dry Equatorial Climatic Zone, Wet Semi Equatorial Climatic Zone and Interior Savannah Climatic Zone respectively and highest in amorphous silicon modules with 1.62%/year and 1.67%/year in Dry Equatorial Climatic Zone and Interior Savannah Climatic Zone respectively. The same module technology degraded differently within the same climatic zone, and from one climatic zone to another. Module degradation rates also varied from one location to another. However, crystalline silicon modules performed creditably in all the climatic zones and thus, could suffice better in these climatic zones in Ghana than amorphous silicon modules.

Calibration of a hydrologic model in data-scarce Alaska using satellite and other gridded products

Study RegionAlaska and hydrologically connected portions of Canada Study FocusRugged terrain and harsh conditions make observational hydroclimatic data, especially runoff data, extremely limited across most of Alaska. Consequently, many previous hydrologic studies in Alaska have focused on smaller-domain trends, where pockets of hydroclimatic observations are clustered. Using a combination of reanalysis and remotely sensed gridded products, we develop a calibration framework for a monthly resolution water budget model, over the entire Alaskan domain, that does not rely on runoff. The domain is comprised of distributed model response units (MRUs), each representing a Hydrologic Unit Code 12 basin. We use a Fourier Amplitude Sensitivity Test (FAST) to inform a two-step calibration process; first calibrating to actual evapotranspiration and then to fractional snow-covered area (fSCA), resulting in a range of parameter solutions for each MRU. New Hydrological Insights for the RegionUsing this framework, the model performs best in the moderate to dry Alaskan interior; in the absence of glaciation and where permafrost is generally not continuous. Modelled runoff for recent decades shows increased runoff trends at lower latitudes and slightly decreased runoff trends at higher latitudes within the Alaskan domain. These findings reveal that reliance upon non-runoff fluxes for model calibration is viable in this cold region and that better characterization of hydroclimatic data is necessary to improve confidence in cold region modeling studies.

Small mammal relative abundance within riparian ecosystems of the Blue Mountains

There is a growing interest and investment in restoring riparian areas in the Pacific Northwest to protect biodiversity and water quality, and to restore quality habitat for threatened fish species. However, these management activities change vegetation conditions and potentially impact terrestrial species in these ecosystems. Our objective was to estimate associations between small mammals and 4 broad cover types—conifers, shrubs, grasses, and forbs—in riparian areas within the Blue Mountains of northeast Oregon, USA. We estimated abundances and spatial association for 10 small mammal species using a multispecies hierarchical abundance model and mark-recapture data collected on 36 sites from 2014 to 2017. We predicted that forest-associated species would be more abundant with greater conifer cover, that increases in shrub cover would favor most species, and that increases in grass and forb cover would favor grassland-associated species. Yellow-pine chipmunks (Tamias amoenus) were positively associated with conifer cover, while long-tailed voles (Microtus longicaudus) and montane voles (Microtus montanus) were negatively associated with conifer cover. Associations with shrub cover were positive for bushy-tailed woodrats (Neotoma cinerea), deer mice (Peromyscus maniculatus), and yellow-pine chipmunks, but negative for montane voles. Bushy-tailed woodrats and montane voles were negatively associated with grass cover. This study is the first to characterize the riparian small mammal communities in this region and provides insights on the effects of restoration activities on riparian ecosystems in dry interior forests and grasslands. We suggest that riparian plantings, a ubiquitous restoration practice, will increase the relative abundances for some, but not all, small mammal species. We also demonstrate use of a new multi-species abundance model that can be a powerful tool for analyzing mark-recapture data because it allowed us to extend the scope of our analysis to data poor species by pooling information with data rich species.

Delineation of dew formation zones in Iran using long-term model simulations and cluster analysis

Abstract. Dew is a non-conventional source of water that has been gaining interest over the last two decades, especially in arid and semi-arid regions. In this study, we performed a long-term (1979–2018) energy balance model simulation to estimate dew formation potential in Iran aiming to identify dew formation zones and to investigate the impacts of long-term variation in meteorological parameters on dew formation. The annual average of dew occurrence in Iran was ∼102 d, with the lowest number of dewy days in summer (∼7 d) and the highest in winter (∼45 d). The average daily dew yield was in the range of 0.03–0.14 L m−2 and the maximum was in the range of 0.29–0.52 L m−2. Six dew formation zones were identified based on cluster analysis of the time series of the simulated dew yield. The distribution of dew formation zones in Iran was closely aligned with topography and sources of moisture. Therefore, the coastal zones in the north and south of Iran (i.e., Caspian Sea and Oman Sea), showed the highest dew formation potential, with 53 and 34 L m−2 yr−1, whereas the dry interior regions (i.e., central Iran and the Lut Desert), with the average of 12–18 L m−2 yr−1, had the lowest potential for dew formation. Dew yield estimation is very sensitive to the choice of the heat transfer coefficient. The uncertainty analysis of the heat transfer coefficient using eight different parameterizations revealed that the parameterization used in this study – the Richards (2004) formulation – gives estimates that are similar to the average of all methods and are neither much lower nor much higher than the majority of other parameterizations and the largest differences occur for the very low values of daily dew yield. Trend analysis results revealed a significant (p&lt;0.05) negative trend in the yearly dew yield in most parts of Iran during the last 4 decades (1979–2018). Such a negative trend in dew formation is likely due to an increase in air temperature and a decrease in relative humidity and cloudiness over the 40 years.

Tectonically and climatically driven mountain-hopping erosion in central Guatemala from detrital &amp;lt;sup&amp;gt;10&amp;lt;/sup&amp;gt;Be and river profile analysis

Abstract. The rise of a mountain range affects moisture circulation in the atmosphere and water runoff across the land surface, modifying the distribution of precipitation and drainage patterns in its vicinity. Water routing in turn affects erosion on hillslopes and incision in river channels on surrounding mountain ranges. In central Guatemala, two parallel, closely spaced mountain ranges formed during two consecutive pulses of uplift, the first between 12 and 7 Ma (Sierra de Chuacús–Sierra de las Minas), and the second after 7 Ma (Altos de Cuchumatanes). We explore the climatic and tectonic processes through which the rise of the most recent range drove the slowing of river incision and hillslope erosion over the previously uplifted range. The 40Ar/39Ar dating of perched volcanic deposits documents the sequential rise and incision of these mountain ranges. Terrestrial cosmogenic 10Be in river sediments indicates that currently hillslopes in the older range erode more slowly than in the younger range (20–150 vs. 300 m Myr−1). These differences mimic the current distribution of precipitation, with the younger range intercepting the atmospheric moisture before it reaches the older range. River channel steepness and deformation of paleovalleys in the new range further indicate that the younger range has been rising faster than the older range up to today. We review how atmospheric moisture interception and river long-profile adjustment to the rise of the new range have contributed to the decline of erosion rates over the old range. We also explore the consequences of this decline and of aridification on the topographic evolution of the older range. The older range undergoes a slow topographic decay, dominated by backwearing, by the stacking of slowly migrating erosion waves along the mountain flanks, and by the formation of pediments around its base. The morphology of the old range is therefore transitioning from that of a front range to that of a dry interior range.

A 14000 year multi-proxy alluvial record of ecotone changes in a Fynbos-Succulent Karoo transition in South Africa

To address long-standing questions concerning Southern Hemisphere climate dynamics and palaeoecological change in southern Africa, a Late Glacial-Holocene alluvial sediment sequence from the relatively dry interior year-round rainfall zone in South Africa was investigated. The study site borders the Fynbos biome and Succulent Karoo biome ecotone, and comprises a rare stratified sequence of sandy and organic-rich silt deposits, shown to span the last 14,000 years. A high resolution multi-proxy record of ecological change was derived using pollen, phytoliths and organic geochemical analyses. For the period 14–11 ka, significant valley aggradation occurred under relatively drier conditions, followed, during the early and middle Holocene, by alternating phases of humid and dry events with higher stream energy, slower accumulation or subtle seasonality changes. A transition from relatively humid to more arid conditions at 4–3 ka is identified and is consistent in timing with several interior year-round rainfall zone records. Results revealed alternations of fynbos and karroid elements and C3/C4 grasses throughout the last fourteen thousand years, but did not suggest large-scale biome shifts. The record joins a growing number of sites contributing to debate over the complex atmospheric-oceanic drivers of palaeoclimate in this region. These data broadly fit to the regional pattern for the southernmost interior of South Africa in showing alternating influences from the westerly winter rain systems in the early Holocene, with a greater contribution from subtropical summer rain system during the middle and later Holocene.

CONSTRUCTION OF DRY GATES FOR THE DEVELOPMENT OF INTERMODAL TRANSPORT OF GOODS IS THE BEST OPPORTUNITY TO REDUCE THE TRAFFIC VOLUME IN THE CENTRAL AREA OF ALBANIA

This analysis briefly identifies the state of Intermodal Freight Transport in Albania from a perspective in facilitating road traffic on the main axes in the central area of Albania. This study examines the possibilities of planning the location of the dry port in the interior of the territorial space of the central area of Albania. Finally, through this Study, we present the orientations and lessons to be learned from the best practices for the promotion of intermodal freight transport. The overall objective of our study is to contribute to the long-term sustainable development of logistics infrastructure and multimodal transport in Albania and to achieve the expected results as provided in the National Sectorial Transport Strategy 2016-2020, under Strategic Priority 1. The specific objective of this study is to reduce the congestion of traffic volumes on the central road axes, to reduce travel time, to reduce transport costs, to minimize environmental pollution from truck gases, and to increase safety through the development of Intermodal Transport shifting freight flows from road transport to rail transport

Woody vegetation cover, height and biomass at 25-m resolution across Australia derived from multiple site, airborne and satellite observations

Detailed spatial information on the presence and properties of woody vegetation serves many purposes, including carbon accounting, environmental reporting and land management. Here, we investigated whether machine learning can be used to combine multiple spatial observations and training data to estimate woody vegetation canopy cover fraction (‘cover’), vegetation height (‘height’) and woody above-ground biomass dry matter (‘biomass’) at 25-m resolution across the Australian continent, where possible on an annual basis. We trained a Random Forest algorithm on cover and height estimates derived from airborne LiDAR over 11 regions and inventory-based biomass estimates for many thousands of plots across Australia. As predictors, we used annual geomedian Landsat surface reflectance, ALOS/PALSAR L-band radar backscatter mosaics, spatial vegetation structure data derived primarily from ICESat/GLAS satellite altimetry, and spatial climate data. Cross-validation experiments were undertaken to optimize the selection of predictors and the configuration of the algorithm. The resulting estimation errors were 0.07 for cover, 3.4 m for height, and 80 t dry matter ha-1 for biomass. A large fraction (89–94 %) of the observed variance was explained in each case. Priorities for future research include validation of the LiDAR-derived cover training data and the use of new satellite vegetation height data from the GEDI mission. Annual cover mapping for 2000–2018 provided detailed insight in woody vegetation dynamics. Continentally, woody vegetation change was primarily driven by water availability and its effect on bushfire and mortality, particularly in the drier interior. Changes in woody vegetation made a substantial contribution to Australia’s total carbon emissions since 2000. Whether these ecosystems will recover biomass in future remains to be seen, given the persistent pressures of climate change and land use.

Using Megha‐Tropiques satellite data to constrain humidity in regional convective simulations: A northern Australian test case

AbstractConvective initiation and growth are sensitive to atmospheric conditions, especially humidity, in ways that need to be understood and quantified. It is not clear, however, how well current observations and modelling systems can serve to test this understanding. We simulate multiple cases of convergent cloud lines observed during January 2016 over northeastern Australia using the Weather Research and Forecasting (WRF) model (version 3.7.1), initialized by and nudged to reanalysis data. Overall, WRF appears to skilfully simulate the convergence lines. However, the associated convective clouds as seen by satellite were not properly captured by the model. The model humidity was tested against the current version (V3‐00) of the Megha‐Tropiques satellite, which although up to 30% too moist in the lowest retrieved layer over the dry continental interior compared to radiosondes, is usually accurate to within ±10% near the cloud lines. Unperturbed WRF simulations were found to be 10–20% too dry in this region. Compensating for this humidity bias via the model initialization produced more realistic simulations of clouds and convection, and this had a comparable or larger impact than changing model physics. This result highlights the importance of observations of water vapour that are accurate and have good spatial coverage, especially in the lower troposphere, for properly constraining simulations of convective environments and for model evaluation of moist processes.

Estimating actual versus detected road mortality rates for a northern viper

Mitigation of adverse effects of roads on wildlife benefits from a fundamental understanding of the number of animals killed by traffic. Road surveys are a key part in quantifying this mortality; however, without accounting for scavenging and observer detection rates, this method only reveals a minimum number of roadkilled animals. We quantified western rattlesnake (Crotalus oreganus) road mortality on a two-lane road in the dry interior of British Columbia, Canada. In 2015, 2016 we repeatedly surveyed 11.7 km of this road by walking, driving, and cycling. We determined the rate of carcass removal by scavengers and observer detection probability during walking surveys using planted snake carcasses. Fifty-two percent of carcasses were removed from the road by scavengers in two days, while 11% remained for >14 days. The mean observer detection probability was 0.76 for a team of two observers conducting surveys by walking. The mean road mortality rate, which accounts for scavenging and observer detection during walking surveys, was 0.06 rattlesnake deaths/km/day or 124 rattlesnake deaths/year based on mean rattlesnake active season duration. The estimated number of rattlesnake deaths was 2.7times the number of dead rattlesnakes detected through all surveys and incidental observations combined. Overall, walking surveys detected only 8% of the estimated rattlesnake deaths. Incidental observations of carcasses made while driving at other times in the study area were numerous, however the detection rate per kilometer was very low compared to more rigorous survey methods. The results highlight the magnitude of snake road deaths that can occur on a two-lane road with just 350 vehicles per day bisecting a wildlife reserve, the importance of standardized surveys and accurate assessments of sources of error in road mortality research, and the value of a model that can be used to calculate detection rates of roadkilled wildlife by trained observers.

Essential oil composition of Pentzia incana (Asteraceae), an important natural pasture plant in the Karoo region of South Africa

Pentzia incana is one of the most important of all natural pasture plants in the dry interior (Karoo) region of South Africa. This highly aromatic shrub is thought to be responsible for the distinctive flavour of Karoo lamb (a registered geographical indication), yet the essential oil is here characterised for the first time. Leafy twigs are traditionally chewed for relief of stomach ache. Essential oil is associated with numerous small, multicellu- lar glands. Gas chromatography and gas chromatography/mass spectrometry analysis of 17 essential oil samples from five populations showed considerable variation in both yield (0.12% to 0.88% dry weight) and composition. Of interest was the presence of one major biosynthetic group comprising yomogi alcohol (to 38.9%), artemisia alcohol (to 26.1%), artemisia ketone (to 35.0%) and artemisyl acetate (to 9.4%). High levels of fragranol (26.9%) and fragranyl acetate (27.1%) were observed only in a single specimen. Other main compounds were 1,8-cineole (to 16.7%), santolina alcohol (to 11.3%), camphor (to 47.9%), linalyl acetate (to 17.4%) and bicyclogermacrene (to 11.8%). Six of the 10 major compounds were isolated and their identities confirmed by nuclear magnetic resonance. The volatile compounds may possibly be linked to the medicinal use of P. incana, as well as the flavour profile of Karoo lamb.

Shifts in the Source and Composition of Dissolved Organic Matter in Southwest Greenland Lakes Along a Regional Hydro‐climatic Gradient

AbstractDissolved organic matter (DOM) concentration and quality were examined from Arctic lakes located in three clusters across south‐west (SW) Greenland, covering the regional climatic gradient: cool, wet coastal zone; dry inland interior; and cool, dry ice‐marginal areas. We hypothesized that differences in mean annual precipitation between sites would result in a reduced hydrological connectivity between lakes and their catchments and that this concentrates degraded DOM. The DOM in the inland lake group was characterized by a lower aromaticity and molecular weight, a low soil‐like fluorescence, and carbon stable isotope (δ13C‐DOC) values enriched by ~2‰ relative to the coastal group. DOC‐specific absorbance (SUVA254) and DOC‐specific soil‐like fluorescence (SUVFC1) revealed seasonal and climatic gradients across which DOM exhibited a dynamic we term “pulse‐process”: Pulses of DOM exported from soils to lakes during snow and ice melt were followed by pulses of autochthonous DOM inputs (possibly from macrophytes), and their subsequent photochemical and microbial processing. These effects regulated the dynamics of DOM in the inland lakes and suggested that if circumpolar lakes currently situated in cool wetter climatic regimes with strong hydrological connectivity have reduced connectivity under a drier future climate, they may evolve toward an end‐point of large stocks of highly degraded DOC, equivalent to the inland lakes in the present study. The regional climatic gradient across SW Greenland and its influence on DOM properties in these lakes provide a model of possible future changes to lake C cycling in high‐latitude systems where climatic changes are most pronounced.