1928 research outputs found
Sort by
Global Mercury Assessment 2018
Get PDFThe Global Mercury Assessment 2018 is the fourth such assessment undertaken by The United Nations
Environment Programme (UN Environment), following earlier reports in 2002, 2008, and 2013. It is
the second assessment produced by UN Environment in collaboration with the Arctic Monitoring and
Assessment Programme (AMAP). The assessment is supported by a technical background document, the
chapters of which have been prepared by teams of experts and peer-reviewed for scientific quality. This
summary document presents the main findings of the technical document in plain language. Recognizing
the relevance of the results of the Global Mercury Assessment 2018 for policy makers, this section presents
key findings of highest policy relevance
The fossil record of durophagous predation in the James Ross Basin over the last 125 million years
Get PDFWe review the evidence for predation of shelly benthic prey over 125 million years of earth history in the James Ross Basin, Antarctica (~65°S). Although poor in the Early Cretaceous lower parts of the sequence, which represent essentially deeper water facies, evidence for both potential crushers and drillers becomes more apparent in the Santonian–Campanian Santa Marta Formation, and by the Maastrichtian López de Bertodano Formation there is an extensive fossil record of drill holes attributable to naticid gastropods, and some evidence of crushing by decapods crustaceans and possibly other taxa too. This continues at a similar level of intensity across the K/Pg boundary into the Danian Sobral Formation, but is less well constrained in the latest Paleocene–Early Eocene. The most extensive record of predation occurs in the Middle Eocene section of the La Meseta Formation on Seymour Island which also records the highest levels of benthic diversity within the entire basin. This key section is providing some important new evidence to suggest that the rate of acceleration of benthic predation intensity through the Late Mesozoic–Early Cenozoic in the polar regions may be similar to that seen in lower latitude regions. Predator–prey interaction was a key factor in the evolution of polar marine faunas too
Cretaceous Antarctic plesiosaurs: stratigraphy, systematics and paleobiogeography
Get PDFThe last twenty million years (Maastrichtian–Santonian) of Southern Hemisphere plesiosaur history is especially well recorded in the Weddellian Province (Patagonia; Western Antarctica and New Zealand). The oldest Late Cretaceous plesiosaurs, two specimens referred to Polycotylidae indet., come from the Santonian levels of the Santa Marta Formation, while the oldest elasmosaurids come from the lower Campanian of the same formation. In the lower Maastrichtian of the Snow Hill Island Formation the non-aristonectine elasmosaurid Vegasaurus molyi is recorded together with other non-diagnosable elasmosaurid specimens, but no aristonectines are present. Aristonectines appears in the Antarctic record in the upper Maastrichtian of the López de Bertodano Formation and are represented by Morturneria and cf. Aristonectes. The specimens from the upper Campanian previously referred to Aristonectinae indet. are referred to Elasmosauridae indet., shortening the temporal record of Aristonectinae in Antarctica. Therefore aristonectines appears in the Antarctic record in the upper Maastrichtian of the López de Bertodano Formation and are represented by Morturneria and cf. Aristonectes. The Antarctic Cretaceous elasmosaurids show a paleobiogeographic connection with South America and New Zealand (Weddellian Province). This connection is indicated by the shared presence of the Aristonectinae Kaiwhekea katiki (New Zealand) and Aristonectes (Argentina and Chile). Recent phylogenetic analysis recovered the aristonectines within the Weddellonectia clade, which includes the aristonectines and the non-aristonectines Vegasaurus molyi (Isla Vega, Antarctica); Kawanectes lafquenianum (Argentina); Morenosaurus stocki and Aphrosaurus furlongi (California). Among the Weddellonectia, the aristonectines show a relatively large body size and extremely derived features and probably occupied a trophic niche that differed from the trophic niche of other elasmosaurids. By way of contrast Kawanectes lafquenianum is an extremely small body-sized elasmosaurid restricted to marginal marine (probably estuarine) environments. Therefore the Weddellonectia show high morphological and probably high ecological diversity
Late Cretaceous non-avian dinosaurs from the James Ross Basin, Antarctica: description of new material, updated synthesis, biostratigraphy, and paleobiogeography
Get PDFAlthough the fossil record of non-avian dinosaurs from the Cretaceous of Antarctica is the poorest of any continent, fossils representing at least five major taxonomic groups (Ankylosauria, early-diverging Ornithopoda, Hadrosauridae, Titanosauria, and Theropoda) have been recovered. All come from Upper Cretaceous (Coniacian–Maastrichtian) marine and nearshore deposits belonging to the Gustav and Marambio groups of the James Ross Basin at the northern tip of the Antarctic Peninsula. The majority of these finds have come from the Campanian–Maastrichtian Snow Hill Island and López de Bertodano formations of James Ross and Vega islands. Given the rarity of Antarctic Cretaceous non-avian dinosaurs, discoveries of any fossils of these archosaurs, no matter how meager, are of significance. Here we describe fragmentary new ornithischian (ankylosaur and ornithopod) material from the upper Campanian–lower Maastrichtian Cape Lamb Member of the Snow Hill Island Formation and the Maastrichtian Sandwich Bluff Member of the López de Bertodano Formation. One of these specimens is considered to probably pertain to the holotypic individual of the early-diverging ornithopod Morrosaurus antarcticus. We also provide an up-to-date synthesis of the Late Cretaceous non-avian dinosaur record of the James Ross Basin and analyze the biostratigraphic occurrences of the various finds, demonstrating that most (including all named taxa and all reasonably complete skeletons discovered to date) occur within a relatively condensed temporal interval of the late Campanian to early Maastrichtian. Most or all James Ross Basin dinosaurs share close affinities with penecontemporaneous taxa from Patagonia, indicating that at least some continental vertebrates could disperse between southern South America and Antarctica during the final stages of the Mesozoic
Anomalous extensive landfast sea ice in the vicinity of Inexpressible Island, Antarctica
Get PDFOn 10 December 2017, a Chinese research vessel R/V Xuelong encountered an extensive area of landfast ice offshore Inexpressible Island (Antarctica) near the location where the fifth Chinese Antarctic research station is to be built. Using multi-source satellite images and weather data, we analyzed the ice conditions during the event season and reconstructed the development of landfast ice. Two stages in late September and early October were identified as contributing to the final ice extent. These two events are highly related to local- and large-scale weather conditions. Satellite images from 2003 to 2017 showed that four in fifteen years experienced severe landfast ice conditions, suggesting that it is not a rare phenomenon
Workshop Summary: Environmental protection of the High North – How to protect the Arctic from afar?
Get PDFThe Arctic is home to unique habitats that are increasingly threatened by the effects of climate change and the release of pollutants. As the region warms up and becomes more accessible, also the planning and conduct of economic activities puts more stress on the region’s ecosystems. Due to the inevitable linkages between Arctic and non-Arc-tic regions, Arctic states and states that do not directly border Arctic regions are responsible to promote environmental protection of the region.
The expert workshop aimed to enable exchange and discussion on how Arctic Council observers can engage strategically and practically in Arctic environmental protection. In an exchange with states that are active in the High North, indigenous communities, businesses, research, and civil society, potential solutions were developed for a sustainable development in the Arctic that allows reconciling a wide spectrum of interests in the region. Topics included in particular climate change and air pollution control, ship-ping, and tourism
The Asian Forum for Polar Sciences: An assessment of regional cooperation
Get PDFThis paper presents a review of the current status of Asian countries’ relations with Antarctica, aimed at deepening understanding of the role of the Asian Forum for Polar Sciences (AFoPS) in the area covered under the Antarctic Treaty. The paper critically examines the current situation regarding the Asian presence in Antarctica and provides a historical outline of the AFoPS. Whereas the activities of individual Asian countries in Antarctica have been extensively analyzed in previous studies, those of the AFoPS constitute a research gap within the scholarly literature. Therefore, an assessment of the role of the AFoPS within the wider Antarctic region from both the policy and scientific perspectives is necessary to better understand its relationship with other international organizations that are active in the area covered by the Antarctic Treaty. Over the course of its relatively short history, the AFoPS has accomplished a number of achievements. These include the signing of a Memorandum of Understanding with the International Arctic Science Committee and the Scientific Committee on Antarctic Research. Additionally, collaborative activities have been undertaken by members of the Forum, entailing, for example, exchanges of personnel, cooperation and support extended within scientific projects. Consequently, AFoPS member countries that traditionally lack a polar background, such as Thailand and Vietnam, have been able to conduct scientific activities in Antarctica
Characterizing three-dimensional features of Antarctic subglacial lakes from the inversion of hydraulic potential—Lake Vostok as a case study
Get PDFTo estimate basal water storage beneath the Antarctic ice sheet, it is essential to have data on the three-dimensional characteristics of subglacial lakes. We present a method to estimate the water depth and surface area of Antarctic subglacial lakes from the inversion of hydraulic potential method. Lake Vostok is chosen as a case study because of the diverse and comprehensive measurements that have been obtained over and around the lake. The average depth of Lake Vostok is around 345±4 m. We estimated the surface area of Lake Vostok beneath the ice sheet to be about 13300±594 km2. The lake consists of two sub-basins separated by a ridge at water depths of about 200–300 m. The surface area of the northern sub-basin is estimated to be about half of that of the southern basin. The maximum depths of the northern and southern sub-basins are estimated to be about 450 and 850 m, respectively. Total water volume is estimated to be about 4658±204 km3. These estimates are compared with previous estimates obtained from seismic data and inversion of aerogravity data. In general, our estimates are closer to those obtained from the inversion of aerogravity data than those from seismic data, indicating the applicability of our method to the estimation of water depths of other subglacial lakes