Discarded containers on a kent beach

Winter beach surveys of discarded containers at Sandwich Bay showed a wide range of fabrication materials and contents. These were manufactured world-wide and probably distributed by seaborne disposal from local shipping. Although blow moulded polyethylene bottles containing toilet cleansers were commonly observed, there was no evidence to indicate an accumulation of these items in the marine environment.     

Origin of garnet phenocrysts in calc-alkaline rocks

A large number of garnet phenocrysts from Palaeozoic rhyodacites and granodiorite porphyrites from Central and Northeastern Victoria have been analyzed using the electron microprobe. These garnets, from an area of several thousand square miles, are very uniform in composition (dominantly almandine, with subordinate pyrope and minor grossular and spessartine). They show minor zoning with a very thin outer rim slightly richer in almandine and spessartine than the remainder of the phenocryst. They are surrounded by a complex intergrowth of cordierite and hypersthene forming a reaction rim. Resorbed quartz phenocrysts are typically associated with the garnet phenocrysts. The uniform composition, the conspicuous size and the subhedral-euhedral form of the garnet phenocrysts indicate that they crystallized directly from the acid calc-alkaline magma at an early stage of its crystallization. High pressure experimental work on a natural garnet-bearing rhyodacite glass demonstrates that almandine-rich garnet and quartz are near-liquidus phases at 18 and 27 kb , but garnet does not appear until well below the liquidus at 9 kb. A comparison of the composition of the experimentally crystallized garnets with the natural garnets suggests that these acid calc-alkaline magmas began to crystallize at pressures between 9 and 18 kb, i.e. at depths corresponding to the lower crust or upper mantle.     

The closed system pyrolysis of β-O-4 lignin substructure model compounds

Lignin substructure model compounds having a β-O-4 linkage were synthesized. These were guaiacylglycerol-β-guaiacyl ether (GGE) and guaiacylglycerol-β-syringyl ether (GSE) which model guaiacyl and syringyl units respectively. Closed system microscale pyrolysis of GGE and GSE was carried out at 300 °C both in the presence and absence of water vapour. The laboratory degradation of GSE occurred predominantly by breaking the C_β–O bond of the β-O-4 linkage to form the ring B fragment of the model compound. This was followed by demethylation of the aromatic methoxyl groups. Char formation was another significant process during pyrolysis. There are structural features of the char formed during the heating of GGE which indicate incorporation of the remaining fragment of the model compound (ring A coupled with the propyl segment of the aryl ether linkage).     

Regional and local variations in the emerging economic landscape of the new German Länder

Events in eastern Germany since 1989 pose major challenges for geographical interpretation. This paper examines the spatial impacts of the post-unification economic and social upheavals in the new Länder. Using unemployment rates as a key indicator of regional differentiation, spatial variability within the new Länder is examined in terms of two fundamental dimensions. First, the relationship with former patterns of economic specialization is explored, and secondly, the effects of basic geographical properties such as settlement structure, location and peripherality. Prominent regional polarities are described, notably between major agglomeration cores and rural residuals, and between ‘bridgehead’ locations and less-accessible districts. Within this context the paper then identifies some ‘green shoots’ of recovery and new growth. It concludes by emphasizing the importance of incorporating sub-regional variations into any new framework of regional policy.     

Determining the climatic requirements of trees suitable for agroforestry

After fossil fuel burning, clearing of forests for agriculture is the second most significant factor increasing levels of atmospheric carbon dioxide. Replanting trees on previously cleared land around the world could reduce the buildup of atmospheric carbon dioxide. However, forests were usually cleared to grow crops or graze animals, so there is no possibility of completely restoring forests on most cleared lands. There is a need to develop agroforestry systems, which integrate trees with agricultural activities.One of the key problems in developing successful agroforestry systems is identifying which trees can be successfully grown in different areas. This problem will become even greater as tree breeding produces a wider variety of genotypes available for planting. General methods are described to identify where a particular tree (species, provenance or clone) with potential for use in agroforestry systems can be grown. The methods also help to identify locations where particular trees are growing under relatively extreme climatic conditions for that taxa. Conditions at these locations should be carefully evaluated as more reliable future climatic scenarios are developed. In the meantime they could be monitored to provide early warning of the effects of climatic and atmospheric change.     

River system discontinuities due to lateral inputs: generic styles and controls

In alluvial river systems, lateral inputs of water and/or sediment at junctions or undercut hillsides can disrupt what would otherwise be smooth downstream trends in mainstream bed elevation, channel gradient, and bed grain size. Generic styles of mainstream response to lateral inputs are investigated using a one‐dimensional sediment routing model with multiple grain size fractions. Numerical experiments isolate the effects of three para‐meters: ratio of tributary to mainstream water flux (QR), ratio of tributary to mainstream bedload flux (FR), and ratio of tributary to mainstream bedload diameter (DR). The findings are not unduly sensitive to the choice of initial conditions or to approximations made in the model. The primary distinction is between junctions that aggrade, causing local profile convexity with interrupted downstream fining, and junctions that degrade. The immediate effects of aggradation extend further upstream than downstream, whereas degradation is much more subdued and has no upstream impact. Aggradation is typical of coarse inputs (DR > 2), and degradation of fine inputs (DR < 1), but very high ratios of QR to FR also promote degradation. Both aggrading and degrading junctions can lead to a change in mainstream bed grain size well below the junction, with higher ratios of QR to FR producing a coarser distal bed. The effect of a tributary reflects the interplay between additional bed load and additional discharge to transport it. Copyright © 2006 John Wiley & Sons, Ltd.     

Mercury distribution and transport in a contaminated river system in Kazakhstan and associated impacts on aquatic biota

The River Nura in Central Kazakhstan has been heavily polluted by Hg originating from an acetaldehyde plant. A number of studies were undertaken to investigate the transport, fate and bioavailability of Hg in this river system. The sediments within a 20 km section of the river downstream of the effluent outfall canal are highly polluted and are acting as a strong source of surface water contamination. Mercury transport in the river is dominated by the remobilization of contaminated bed sediments and river bank erosion during the annual spring flood. Peak Hg concentrations in unfiltered surface water samples during a larger than usual flood event in 2004 were in the order of 1600–4300 ng L⁻¹. The majority of the particulate-bound Hg appears to be sedimented in the shallow Intumak reservoir 75 km downstream of the source of the pollution, leading to a drop in aqueous Hg concentrations by an order of magnitude. Nevertheless, background concentrations of Hg in surface water are not reached until at least 200 km downstream, and during the flood period Hg is also detected in the terminal wetlands of the river.Mercury concentrations in sediment cores taken from the river bed in the most contaminated section of the Nura ranged from 9.95 to 306 mg kg⁻¹. Methylmercury (MeHg) levels in shallow sediment cores were highest in surface sediments and ranged between 4.9 and 39 μg kg⁻¹, but were generally less than 0.1% of total Hg (THg). A significant inverse relationship was found between THg concentrations and the percentage of MeHg formed in the sediments, irrespective of the sampling depth. The observed relationship was confirmed by comparison with results from a different river system, indicating that it may be true also for other highly contaminated aquatic systems. It is hypothesized that at high THg levels in severely contaminated sediments, the accumulation of MeHg may be limited by increasingly efficient demethylation processes, and that this underlying trend in sediments is the reason why MeHg levels in surface water are often found to be higher at less contaminated sites compared to upstream sites.Mercury concentrations in biota in the most contaminated section of the river were 15–20 times higher than background levels. Fish were found to be impacted for more than 125 km downstream from the source, indicating significant transport of dissolved MeHg to downstream areas and/or in-situ MeHg production in less contaminated downstream reaches. There were also indications that impoundments may increase the bioavailability of Hg.     

Major Miocene geological events in southern Tibet and eastern Asia induced by the subduction of the Ninetyeast Ridge

Cenozoic adakitic rocks in the Gangdese changed from barren continental melts to ore-forming slab melts at ~ 23 Ma. The distribution and chemical characteristics of the ore-forming adakites point to an association with the Ninetyeast Ridge. The subduction of the thick, rigid Ninetyeast Ridge changed the geometry and rheology of the eastern Tibetan Plateau lithosphere and asthenosphere, restrained the eastward escape of asthenospheric mantle as well as continental fragments, and promoted the uplift and building of the Tibetan Plateau, which consequently changed the tectonic and climatic regimes in eastern Asia.