MIS 3 marine and lacustrine sediments at Kriegers Flak,southwestern Baltic Sea

Anjar, J., Larsen, N. K., Björck, S., Adrielsson, L. & Filipsson, H. L. 2010: MIS 3 marine and lacustrine sediments at Kriegers Flak, southwestern Baltic Sea. Boreas, 10.1111/j.1502‐3885.2010.00139.x. ISSN 0300‐9483. Sediment cores from the Kriegers Flak area in the southwestern Baltic Sea show a distinct lithological succession, starting with a lower diamict that is overlain by a c. 10 m thick clay unit that contains peat, gyttja and other organic remains. On top follows an upper diamict that is inter‐layered with sorted sediments and overlain by an upward‐coarsening sequence with molluscs. In this paper we focus on the clay unit, which has been subdivided into three subunits: (A) lower clay with benthic foraminifera and with diamict beds in the lower part; (B) thin beds of gyttja and peat, which have been radiocarbon‐dated to 31–35 ¹⁴C kyr BP (c. 36–41 cal. kyr BP); and (C) upper clay unit. Based on the preliminary results we suggest the following depositional model: fine‐grained sediments interbedded with diamict in the lower part (subunit A) were deposited in a brackish basin during a retreat of the Scandinavian Ice Sheet, probably during the Middle Weichselian. Around 40 kyr BP the area turned into a wetland with small ponds (subunit B). A transgression, possibly caused by the damming of the Baltic Basin during the Kattegat advance at 29 kyr BP, led to the deposition of massive clay (subunit C). The data presented here provide new information about the paleoenvironmental changes occurring in the Baltic Basin following the Middle Weichselian glaciation.     

LL-moments for estimating low flow quantiles / Estimation des quantiles d'étiage grâce aux LL-moments

Abstract

A parameter estimation method is proposed for fitting probability distribution functions to low flow observations. LL-moments are variants of L-moments that are analogous to LH-moments, which were defined for the analysis of floods. LL-moments give higher weights to the small observations. Expressions are given that relate them to the probability distribution function for the case of normal, Weibull and power distributions. Sampling properties of the LL-moments and of the distribution parameters and quantiles estimated by them are found by a Monte Carlo simulation study. It is shown on an example that the low flow quantile estimates obtained by LL-moments may be significantly different from those obtained by L-moments.     

Regionalization approaches for the periodic parameters of monthly flows: a case study of Ceyhan and Seyhan River basins

Five alternative regionalization approaches in two broad categories, named function‐free and functional approaches, have been proposed to predict periodic behaviours in the basic parameters of monthly stream flows throughout homogeneous regions defined. Function‐free and functional approaches rely on the standardized (or normalized) forms of raw and fitted values of the monthly periodic parameters considered. Homogeneous regions are identified based on these standardized/normalized parameters by means of the hierarchical clustering analysis. The proposed models are tested for two major river basins in south Turkey. It is concluded that the proposed regional models are very effective to estimate periodic behaviour of monthly flows. The functional approaches are quite plausible, and the function‐free approach needs much more parameters. Both types of regionalization approaches can be reliably used to get regional monthly flow estimates for the flow sections where monthly records are not available or too short. Copyright © 2010 John Wiley & Sons, Ltd.     

International fisheries regime effectiveness—Activities and resources of key actors in the Southern Ocean

Many contemporary environmental challenges are truly global and span several organizational and geographical borders. Research on international environmental regimes has, over the last couple of decades, identified several important factors that contribute to a more effective governance of global ecological resources, but few studies have addressed the different roles certain influential individual organizations play in determining regime effectiveness. Here we address this question by studying a relatively successful fishery governance system in the Southern Ocean. By drawing on insights from the research fields of common-pool resource management and international environmental regimes, we demonstrate that organizations engaged in certain combinations of activities, and that have access to certain combinations of resources stand out as important for regime effectiveness. In particular, collaboration with other flag states and being politically well-connected stand out as important explanatory factors. However, access to advanced technology, engagement in public campaigns, and being active in the field are other factors that, in different combinations, also seem to explain organizational importance. Furthermore, governmental and non-governmental organizations tend to perform different sets of activities and possess different resources, thereby complementing each other. Also, organizations doing similar things are often of different types with different mandates and objectives. This could contribute to improved adaptability and responsiveness to change at the larger regime level. Finally, we discuss some potential implications of our results for capacity-building in international environmental governance.     

Climatic control of the surge periodicity of an Icelandic outlet glacier

Surging outlet glaciers are important in draining large ice caps, but the mechanisms controlling surge periodicities are poorly known. We investigated a sediment sequence from the glacier‐fed Lake Lögurinn in eastern Iceland, and our unique annually resolved data, based on sedimentary varves, imply that Eyjabakkajökull, an outlet glacier of Vatnajökull, began surging about 2200 cal a BP (before 1950 AD). Approximately 1700 cal a BP, the glacier started to surge at a uniform 34‐ to 38‐year periodicity that prevailed until the coldest part of the Little Ice Age when the periodicity almost halved to 21–23 years. Since the late 1800 s the surge periodicity of Eyjabakkajökull has returned to a longer period of 35–40 years. We suggest that surge periodicities of Eyjabakkajökull are forced by climatically driven mass balance changes, which may be a common forcing factor for similar surge‐type outlet glaciers. Copyright © 2011 John Wiley & Sons, Ltd.     

Shock experiments in support of the Lithopanspermia theory: The influence of host rock composition,temperature, and shock pressure on the survival rate of endolithic and epilithic microorganisms

Abstract– Shock recovery experiments were performed with an explosive set‐up in which three types of microorganisms embedded in various types of host rocks were exposed to strong shock waves with pressure pulse lengths of lower than 0.5 μs: spores of the bacterium Bacillus subtilis, Xanthoria elegans lichens, and cells of the cyanobacterium Chroococcidiopsis sp. 029. In these experiments, three fundamental parameters were systematically varied (1) shock pressures ranging from 5 to 50 GPa, (2) preshock ambient temperature of 293, 233 and 193 K, and (3) the type of host rock, including nonporous igneous rocks (gabbro and dunite as analogs for the Martian shergottites and chassignites, respectively), porous sandstone, rock salt (halite), and a clay‐rich mineral mixture as porous analogs for dry and water‐saturated Martian regolith. The results show that the three parameters have a strong influence on the survival rates of the microorganisms. The most favorable conditions for the impact ejection from Mars for microorganisms would be (1) low porosity host rocks, (2) pressures <10–20 GPa, and (3) low ambient temperature of target rocks during impact. All tested microorganisms were capable of surviving to a certain extent impact ejection in different geological materials under distinct conditions.     

Reciprocal influence of Kürtün Dam and wastewaters from the settlements on water quality in the stream Harşit,NE Turkey

This paper aims to reveal the reciprocal influence of Kürtün Dam and wastewaters from the settlements on the water quality in the stream Har?it, NE Turkey. Several key water-quality indicators were measured: water temperature (T), pH, dissolved oxygen (DO), electrical conductivity, water hardness, chemical oxygen demand (COD), ammonium nitrogen (NH₄ ⁺–N), nitrite nitrogen (NO₂ ^?–N), nitrate nitrogen (NO₃ ^?–N), total Kjeldahl nitrogen (TKN), total nitrogen (TN), orthophosphate phosphorus (PO₄ ^3?–P), and methylene blue active substances (MBAS). The monitoring and sampling studies were conducted every 15 days from March 2009 to February 2010 at two stations selected in the upstream and downstream of the Kürtün Dam. It was concluded that the Kürtün Dam Lake had a high-quality water in terms of T, pH, DO, COD, NH₄ ⁺–N, NO₂ ^?–N and NO₃ ^?–N values, but slightly polluted water with respect to TKN, PO₄ ^3?–P, and MBAS according to the Turkish Water Pollution Control Regulation. The dam improved the stream water quality by increasing the DO concentration, and decreasing the NO₂ ^?–N and PO₄ ^3?–P concentrations thanks to its hydraulic residence time despite the wastewater discharge by the nearby settlements. However, the wastewater discharge deteriorated the stream water quality increasing the COD, NH₄ ⁺–N, NO₃ ^––N, and TN concentrations.     

Investigation of the failure mechanism and stabilization of a landslide in weathered tuffite,Giresun, northeastern Turkey

This study investigates the causes and failure mechanism of the Aksu landslide that occurred during the construction of the Giresun–Espiye road between KM: 1 + 030–1 + 170 in northern Turkey and recommends proper stabilization techniques. For the purpose of investigating the causes and mechanism of this slope failure, engineering geological mapping, geotechnical investigation and rock mass characterization were performed. From top to bottom, weathered tuffite, tuffite, flysch, and dacitic tuffite were the major units in the study area. The disturbance of the slope by the excavations performed at the toe of the slope (i.e., due to the foundation excavation for the Tünel restaurant building and for the road cut) led to a “translational slide”. The “translational slide” occurred in completely weathered tuffite due to the disturbance of the stability of the slope by the excavations performed at the toe of the slope, particularly for the foundation excavation of the Tünel restaurant building and for the road cut along the Giresun–Espiye road. The rise in the groundwater level was also another important factor that has contributed to the occurrence of the landslide. After establishing the geometry of the landslide in detail, the shear strength parameters of the failure surface were determined by the back analysis method. Sensitivity analyses were performed and landslide failure mechanisms were modeled to quantify the contributing factors that have caused the formation of the Aksu landslide. The influence of an earthquake was investigated through pseudostatic slope stability analysis. Toe buttressing, ground water drainage, and surface water drainage alternatives were considered for stabilizing the slope.     

Groundwater quality assessment and its suitability in Çeltikçi plain (Burdur/Turkey)

The Çeltikçi (Burdur) plain is located in the southwest of Turkey and is a semi-closed basin. Groundwater is densely used as drinking, irrigation and domestic water in the plain. Hydrogeochemical processes controlling groundwater chemistry and geochemical assessment of groundwater were investigated in the Çeltikçi (Burdur/Turkey) plain. In this study, groundwater samples for two seasons were analyzed and major ion chemistry of groundwater was researched to understand the groundwater geochemistry. Two major hydrochemical facies (Ca–HCO₃ and Ca–Mg–HCO₃) were determined in the area. Various graphical plots and multivariate statistical analysis were used for identifying the occurrence of different geochemical processes. In the study area, weathering is one of the key geochemical processes which controlled the solute concentration in groundwater. Chemical indexes such as sodium adsorption ratio, %Na, residual sodium carbonate, magnesium hazard and permeability index were calculated and results show that groundwater is suitable for irrigation purpose except for permeability index values. Concentrations of Mn, NO₃ and total hardness exceed the prescribed limits of WHO and are the major limiting parameters of groundwater use for potable and domestic purposes.