Results from a Multi-disciplinary Sedimentary Pilot Study of Tectonic Lake Iznik (NW Turkey) – Geochemistry and Paleolimnology of the Recent Past

A limnogeological reconnaissance study was carried out on Lake Iznik, located in the southeast of the Marmara region of Turkey, involving a seismic survey and collection of short sediment cores. This lake is located on the middle branch of the North Anatolian Fault Zone (NAFZ), a transform plate boundary between the Eurasian and Anatolian Plates. It is, therefore, tectonically active and offers an opportunity to investigate the interplay of sedimentary and seismo-tectonic processes, as well as climate change and human impact in the region. Short cores of the three sub-basins, maximum length of 35.5 cm, recovered non-laminated, blackish clays and silts with varying amounts of biogenic and minerogenic (allochthonous, autochthonous) material, which documented almost the last 80 years of deposition and environmental history. High sedimentation rates in the deeper core sections are accompanied by changes in land use (conversion of woodland to farmland) in the northern areas of Lake Iznik, which caused the deposition of more weathered material (high K/Na ratios) and higher contents of Mn in the lake. A tendency towards eutrophic conditions within the last 20 years is indicated by high nutrient content (N, TOC, P), decreasing C/N-ratios, and characteristic diatom and cladoceran associations. Also increased pollution is revealed by higher Pb, Cu, and Zn contents and increased supply of human and animal faeces (high coprostanol content) during the last two decades. But simultaneous lower sedimentation rates towards the core tops complicate the reconstruction of recent and past eutrophication and pollution states of Lake Iznik. This requires an extension of the pilot study and deeper sediment cores, to recover non-anthropogenic influenced sediment levels.     

Greenhouse Gas Emissions and Costs over the Life Cycle of Wood and Alternative Flooring Materials

Increased use of wood can substitute more energy demanding products and thus contribute to a long-term solution to the global warming problem. The aim of this article is to provide an empirical study on this substitution impact, its cost-effectiveness, and which methodological assumptions that are of highest importance for the results obtained. We have made a case study where we compare use of various flooring materials. The results show that floor covering in solid oak causes lower greenhouse gas (GHG) emissions than the other materials. The difference can be ranked in the following order, after their potential for reduction in GHG emissions: Carpet in wool, carpet in polyamide, vinyl, and linoleum. At 2% pro anno discount rate, the avoided GHG emission in tons per m³ of oak flooring used is 0.1–1.9 for linoleum, and 11.8–15.5 for wool carpets. Unless the solution in solid oak is on total less expensive over the lifetime of the building, only the price of avoided emissions from a substitution between solid oak and carpet in wool is reasonable, compared to present carbon fees. The assumptions that influence the result most are choice of discount rate, carbon fixation on forest area, and waste handling. Empirical case studies like this indicate GHG emission reduction potentials caused by substitution, but should be complemented by dynamic input/output analyses and econometric studies. To analyse the flow of CO₂ over time, they should also be linked to forest management models.     

Fabric studies within the Cascade Lake shear zone, Sierra Nevada, California

The Cascade Lake shear zone occurs on the eastern margin of the Tuolumne Intrusive Suite, Sierra Nevada Batholith, California. Foliation in the zone is NNW trending and subvertical, and lineation is moderately south plunging. Deformation is syn-tectonic with emplacement of the Cathedral Peak granodiorite. A deformation gradient exists toward the NE margin of this pluton, with higher strains and lower temperatures of deformation found near the contact. We compare fabric data collected very densely in this shear zone using several techniques: field fabrics, 3D orientation of K-feldspar megacrysts, and AMS (anisotropy of magnetic susceptibility) analysis. In general, the results from the three different methods are in agreement. Deformation in this shear zone is part of a larger pattern of deformation within the Cathedral Peak granodiorite, as recorded by AMS analysis, and dextral shearing associated within the last stage of plutonism within the Sierra Nevada magmatic arc.     

Tetrahedral Plots of the Phase Relations for Basalts

The phase relations of quaternary systems are generally represented by projections onto ternary compositional planes. Such projections often obscure relationships that would only be evident in a three-dimensional tetrahedral plot. The tetrahedral plot requires that compositions of the minerals and melts be transformed into Cartesian coordinates. It is shown here how this transformation is carried out. The application is demonstrated by tetrahedral plots of experimental melt compositions of partially molten lherzolite. Furthermore, the plot can be used to evaluate whether or not a particular basaltic composition represents a primary melt. The methods are applicable to any four-component system.     

Meio-epifaunal wood colonization in the vicinity of methane seeps

In deep-sea environments, plant remains of several origins are found, including branches, twigs, leaves, and wood pieces, among others. As most of the deep-sea bottoms are oligotrophic and nutrient-limited, plant remains provide an oasis of localized organic enrichment and a substrate for colonization. Sunken wood was suggested to play an important evolutionary role in the diversification of chemosynthetic ecosystems, possibly representing stepping stones for the colonization between vent and seep ecosystems. In order to understand colonization processes of the Pacific Costa Rican meio-epifaunal assemblages associated with sunken wood, a field experiment was conducted on Mound 12 (8°55.778′N, 84°18.730′W) at ~1,000 m water depth. Woodblocks were placed in four different habitats (Mussel beds, tube worms, near mussel beds, rubble bottoms), and different local environmental conditions (seepage-active and seepage-inactive sites). Seven experimental Douglas fir woodblocks (each 1,047 cm² in surface area) were deployed from the R/V Atlantis using the manned submersible Alvin in February 2009 and recovered after 10.5 months in January 2010. Sample processing and analyses led to a data set of abundance (total 9,951 individuals) and spatial distribution of nine meio-epifaunal higher taxa/groups. Meio-epifaunal densities on individual woodblocks ranged from 3 to 26 ind.10 cm². Copepods accounted for the highest abundances (75.1%), followed by nauplii larvae (11.7%) and nematodes (9.8%). The maximum number of individuals (26.3 ind.10 cm⁻²) was found in blocks placed in seepage-inactive areas (near active mussel beds) in contrast to 2.9 ind.10 cm⁻² in active areas (within a mussel bed). A hierarchical cluster analysis grouped blocks according to seepage activity and not to habitat, but tests of similarity showed no significant differences in higher taxon composition and abundances, probably owing either to substrate homogeneity or low sample size. Copepods were the most abundant representatives, suggesting that this group is one of the most successful in colonizing in the early stage of succession, in this case while hardwood substrates are not yet decomposed or bored by bivalves.     

Shark interactions in pelagic longline fisheries

Substantial ecological, economic and social problems result from shark interactions in pelagic longline fisheries. Improved understanding of industry attitudes and practices towards shark interactions assists with managing these problems. Information on fisher knowledge and new strategies for shark avoidance may benefit sharks and fishers. A study of 12 pelagic longline fisheries from eight countries shows that incentives to avoid sharks vary along a continuum, based on whether sharks represent an economic disadvantage or advantage. Shark avoidance practices are limited, including avoiding certain areas, moving when shark interaction rates are high, using fish instead of squid for bait and deeper setting. Some conventionally employed fishing gear and methods used to target non-shark species contribute to shark avoidance. Shark repellents hold promise; more research and development is needed. Development of specifically designed equipment to discard sharks could improve shark post release survival prospects, reduce gear loss and improve crew safety. With expanding exploitation of sharks for fins and meat, improved data collection, monitoring and precautionary shark management measures are needed to ensure that shark fishing mortality levels are sustainable.