The Russian Arctic coastal zone management problems: past lessons and new realities

The growing attention to the development of coastal zone resources is notable not only for moderate and southern latitudes but also in the Arctic regions. In Russia this process has a history related to exploration of non-renewable resources and the long-term policy of moving labour forces to the Far North and East. The role of the Russian Arctic coastal zone in the national economy had been stimulated by active usage of the Northern Sea Route for 60 years as a mainstream Arctic transport line. Diversified human usage of all kinds of natural resources is getting more controversial. A deep revaluation of existing methods and management approaches is needed in accordance with the complexities of Russian social/economic and ecological factors in the Arctic. The modern challenge of transition towards sustainable development also needs to be reevaluated. The last decade has shown a real effort of all Arctic countries to expand cooperation in joint scientific multidisciplinary studies. The studies are aimed at elaboration of common views on Arctic development and protection of environment. Moreover, the Arctic shelf and coastal zone are getting a new arena of international investments for industrial projects and implementation due to recovery of huge deposits of oil and gas resources of sophisticated technologies. All this makes international scientific cooperation more of a reality.     

Jom-Bolok Holocene volcanic field in the East Sayan Mts., Siberia,Russia: structure,style of eruptions,magma compositions,and radiocarbon dating

Jom-Bolok volcanic field is located in the East Sayan Mts. of Siberia (Russia), a portion of the Asian convergent zone. It is located at the boundary of the Riphean Tuva-Mongolia massif, which was probably reactivated because of the interplay between far-field tectonic stress derived from the India–Asia collision zone and extension in the south-western Baikal rift system. The volcanic field comprises a number of hawaiitic lava flows, of various lengths, which flowed down paleorivers. Flows were fed by fissure eruptions and the largest lava flow field was dated as 7,130?±?140 cal ¹⁴C years BP using a buried organic sample found inside the associated cinder cone. This lava flow field is about 70 km long, ～100 km² in area, and 7.9 km³ in volume. The area and volume of this flow field ranks this eruption highly in the global record of fissure-fed effusive eruptions. This lava flow field makes up 97% of the entire Jom-Bolok volcanic field, a fact which raises a puzzling question: why and/or how did a relatively small-volume volcanic field produce such a large-volume individual eruption? A working hypothesis is that a pond of sublithospheric melt accumulated over a relatively prolonged period. This was then rapidly drained in response of tectonic changes triggered by unloading of ice in the Early Holocene.     

Production, retention and export of zooplankton faecal pellets on and off the Iberian shelf, north-west Spain

Vertical distribution of faecal pellets (FP), their sedimentation and the production rates of FP by mesozooplankton were studied during a cruise on and off the Iberian shelf in August 1998. The cruise was divided into two legs, each of them a short-term Lagrangian drift experiment. FP were collected with water bottles, with drifting sediment traps and during experiments carried out onboard the ship. The pellets were enumerated and their biovolumes and carbon contents (FPC) were calculated.The standing stock of FP in the upper 50 m was on average three times higher during the first on-shelf experiment than during the second off-shelf experiment. There were large diurnal variations, but no clear pattern emerged between day and night sampling. The vertical export of FPC from the upper, productive layer was on average one order of magnitude greater on the shelf (range 6–160 mg.m⁻².d⁻¹) compared to the off-shelf experiment (range 1–30 mg.m⁻².d⁻¹). FPC sedimentation explained 20% of the total POC export from the euphotic layer on the shelf, but <5% off the shelf. FP sedimentation was dominated by medium-sized cylindrical pellets (40–60 μm in diameter), but larger cylindrical pellets (60–100 μm in diameter) also played an important role. The smaller FP size fractions were never of any significance, in spite of the high abundance of smaller calanoid and cyclopoid copepods. The community production of FPs by mesozooplankton were calculated for the off shelf stations, and the average retention potential of FP in the upper 200 m was estimated to be 98%. Thus retention processes are clearly important for cross-shelf advection of FPs, their injection into the deep ocean and in the regulation of pelagic benthic coupling.     

Sedimentary iron inputs stimulate seagrass (Posidonia oceanica) population growth in carbonate sediments

The relationship between sedimentary Fe inputs and net seagrass population growth across a range of Posidonia oceanica meadows growing in carbonate Mediterranean sediments (Balearic Islands, Spain; SE Iberian Peninsula, Spain; Limassol, Cyprus; Sounion, Greece) was examined using comparative analysis. Sedimentary Fe inputs were measured using benthic sediment traps and the net population growth of P. oceanica meadows was assessed using direct census of tagged plants. The meadows examined ranged from meadows undergoing a severe decline to expanding meadows (specific net population growth, from −0.14 yr⁻¹ to 0.05 yr⁻¹). Similarly, Fe inputs to the meadows ranged almost an order of magnitude across meadows (8.6–69.1 mg Fe m⁻² d⁻¹). There was a significant, positive relationship between sedimentary iron inputs and seagrass net population growth, accounting for 36% of the variability in population growth across meadows. The relationship obtained suggested that seagrass meadows receiving Fe inputs below 43 mg Fe m⁻² d⁻¹ are vulnerable and in risk of decline, confirming the pivotal role of Fe in the control of growth and the stability of seagrass meadows in carbonate sediments.     

Microbially mediated methane and sulfur cycling in pockmark sediments of the Gdansk Basin, Baltic Sea

In the Russian sector of the Gdansk Basin (Baltic Sea), high organic matter influx fuels microbial processes resulting in the formation of reduced sediments with elevated methane concentrations. Investigated areas of geoacoustic anomalies (～245 km²) were found to contain three distinct geomorphologic structures (pockmarks), with a total area of ～1 km². Methane anomalies recorded in the water above one of these pockmarks were traced as high as 10 m above the bottom. In pockmark sediments, sulfate reduction and anaerobic oxidation of methane (AOM) occurred at high rates of 33 and 50 µmol dm^?3 day^?1, respectively. Integrated over 0–180 cm sediment depths, AOM exceeded methanogenesis almost tenfold. High AOM rates resulted from methane influx from deeper sediment layers. The δ¹³C signature of methane carbon (?78.1 to ?71.1‰) indicates the biogenic origin of pockmark methane. In pockmark sediments, up to 70% of reduced sulfur compounds was possibly produced via AOM.     

Geology of the Murcia Valley and Flood Plain Modifications in the Construction of the Circus Maximus,Rome, Italy

This paper presents a morphological and hydrogeological reconstruction of the Murcia Valley at the location of the great Roman stadium Circus Maximus in Rome. We reconstruct a valley segment using ERT (electrical resistivity tomography) and geoarchaeological drilling data that identified three main layers. The basal layer, with high resistivity values and convex shapes, is correlated to alluvial gravel and lithified silt‐clay sediments. The middle layer shows low‐to‐medium resistivity values extending to concavities between the basal convex shapes. The very low resistivity values of this middle layer characterize elliptical to circular morphologies and have been ascribed to the presence of water‐saturated clay‐silt and peaty sediments. The surface layer is characterized by widespread lateral inhomogeneity interpreted as anthropogenic fill. The data indicate a pre‐Roman anastomosed alluvial plain subsequently modified by human intervention. In an effort to reclaim the valley for construction of the Circus, the Romans utilized the natural topography and created a central embankment, later becoming the Spina, by filling depressions with sand taken from adjacent bars. Our study contributes to (1) knowledge of the pre‐Roman landscape, (2) understanding anthropogenic modification of the Murcia Valley flood plain, and (3) archaeological interpretation of the monument.