Search results for "Arctic"
showing 10 items of 565 documents
Chlorine partitioning in the lowermost Arctic vortex during the cold winter 2015/2016
2019
Activated chlorine compounds in the polar winter stratosphere drive catalytic cycles that deplete ozone and methane, whose abundances are highly relevant to the evolution of global climate. The present work introduces a novel dataset of in situ measurements of relevant chlorine species in the lowermost Arctic stratosphere from the aircraft mission POLSTRACC–GW-LCYCLE–SALSA during winter 2015/2016. The major stages of chemical evolution of the lower polar vortex are presented in a consistent series of high-resolution mass spectrometric observations of HCl and ClONO2. Simultaneous measurements of CFC-12 are used to derive total inorganic chlorine (Cly) and active chlorine (ClOx). The new data…
Improved synthesis of Bn5CpRu(CO)2Cl and its application as racemization catalyst in preparative-scale metalloenzymatic dynamic kinetic resolution of…
2010
An improved gram-scale synthesis of Bn5CpRu(CO)2Cl is reported based on heating of pentabenzylcyclopentadiene with Ru3(CO)12 at 160 °C under argon atmosphere in mesitylene followed by addition of chloroform, continued heating, and evaporation of the solvents. Subsequent washing of unreacted ligand precursor with hexane provided pure title compound in 77 % yield. In combination with Candida antarctica lipase B (CAL-B) (Novozym 435), this complex forms a highly active racemization catalyst for metallo-enzymatic dynamic kinetic resolution (DKR) of secondary alcohols as demonstrated in the present work by converting 100 g of racemic 1-phenylethanol to (R)-1-phenylethanol in >99 % ee and 93 %…
Chlorophenol Compounds in Snow
1988
Polychlorinated phenols, guaiacols and catechols have been studied in snow from North Pole, North, Central and South Finland. Only Central and South Finland samples contained known compounds above limit of determination 0.5 ng/1. Airborne chlorophenol pollution appeared to be very much higher in South than in Central Finland.
Species of Acryptolaria Norman, 1875 (Cnidaria: Hydrozoa) collected by US Antarctic and sub-Antarctic expeditions.
2020
Acryptolaria is a worldwide genus of deep-water benthic hydroids. The genus has relatively high species diversity, with 36 species described so far, yet most of them have been reported only occasionally. As a result, scientific knowledge of their ecology and distribution is scarce. Here I present the results of the study of species of Acryptolaria collected during several Antarctic and sub-Antarctic expeditions under the United States Antarctic Research Program between 1958 and 1986. Eight species were found in the collection (plus one determined to the genus level), with A. operculata having the highest occurrence. Acryptolaria flabellum is reported for the second time; the study also repr…
Southern Ocean areas of endemism: a reanalysis using benthic hydroids (Cnidaria, Hydrozoa)
2013
The biogeographic history of the Southern Ocean (SO) fauna is complex and poorly studied, especially the areas of endemism. We reanalyzed the data of Marques & Peña Cantero (2010), along with other geographical records of endemic benthic hydroids below 45°S. A Parsimony Analysis of Endemicity (PAE) based on 5° latitude by 5° longitude matrix with 61 species resulted in eight areas of endemism. We discuss these results in the context of different hypotheses of the evolution of the SO fauna and previously proposed biogeography patterns.
The impact of the Little ice age on coccolithophores in the central Mediterranea Sea
2010
The Little Ice Age (LIA) is the last episode of a series of Holocene climatic anomalies. There is still little knowledge on the response of the marine environment to the pronounced cooling of the LIA and to the transition towards the 20th century global warming. Here we present decadal-scale coccolithophore data from four short cores recovered from the central Mediterranean Sea (northern Sicily Channel and Tyrrhenian Sea), which on the basis of <sup>210</sup>Pb activity span the last 200–350 years. The lowermost part of the record of one of the cores from the Sicily Channel, Station 407, which extends down to 1650 AD, is characterized by drastic changes in productivity. Specific…
Serotoninergic Modulation of Phototactic Variability Underpins a Bet-Hedging Strategy in Drosophila melanogaster
2021
When organisms’ environmental conditions vary unpredictably in time, it can be advantageous for individuals to hedge their phenotypic bets. It has been shown that a bet-hedging strategy possibly underlies the high inter-individual diversity of phototactic choice in Drosophila melanogaster. This study shows that fruit flies from a population living in a boreal and relatively unpredictable climate have more variable variable phototactic biases than fruit flies from a more stable tropical climate, consistent with bet-hedging theory. We experimentally show that phototactic variability of D. melanogaster is regulated by the neurotransmitter serotonin (5-HT), which acts as a suppressor of the var…
Burning of Logged Sites to Protect Beetles in Managed Boreal Forests
2007
: Natural disturbance–based management and conservation strategies are needed to protect forest biodiversity. Boreal forests of northern Europe are typically clearcut and otherwise intensively managed for timber production. As a result, natural disturbances such as forest fires have became rare and the volume of dead wood has decreased. These changes have had a profound negative effect on species that depend on dead wood (saproxylic). Therefore, it is important to determine whether modifications of forest management methods can enhance the survival of these species. In our study area in southern Finland, we determined whether burning of logged sites and leaving trees (i.e., retention trees)…
Ecological Efficiency of Voluntary Conservation of Boreal-Forest Biodiversity
2008
Current networks of protected areas are biased in many countries toward landscapes of low productivity. Voluntary conservation incentives have been suggested as a socially acceptable way to supplement existing networks with more productive, privately owned areas of high priority for nature conservation. The limited resources committed to nature conservation demand cost-efficiency. Efficiency, however, depends not only on costs incurred to society from alternative ways of maintaining biodiversity but also on ecological values that can be captured. We examined the ecological efficiency of the new market-based voluntary program to preserve forest habitats on private land in southwestern Finlan…
New discoveries in New World Atissini as revealed in revision of Pelignellus Sturtevant & Wheeler (Diptera: Ephydridae)
2019
Pelignellus is resurrected from synonymy with Atissa and is revised. The genus and both included species—P. subnudus Sturtevant & Wheeler from the USA (California) and P. freidbergi n. sp. from Central America (Costa Rica, El Salvador, Panama)—are described with an emphasis on structures of the male terminalia, which are fully illustrated. The species are keyed and their distribution data are provided. For perspective and to facilitate recognition of genera and species, the tribe Atissini is diagnosed and a key to genera is provided.