Biofuel scenarios in a water perspective: The global blue and green water footprint of road transport in 2030

Concerns over energy security and climate change stimulate developments towards renewable energy. Transport is expected to switch from fossil fuel use to the use of fuel mixtures with a larger fraction of biofuels, e.g. bio-ethanol and biodiesel. Growing biomass for biofuels requires water, a scarce resource. Existing scenarios on freshwater use usually consider changes in food and livestock production, and industrial and domestic activities. This research assesses global water use changes related to increasing biofuel use for road transport in 2030 and evaluates the potential contribution to water scarcity. To investigate water demand changes related to a transition to biofuels in road transport, the study combines data from water footprint (WF) analyses with information from the IEA APS energy scenario for 2030. It includes first-generation biofuels, bio-ethanol from sugar cane, sugar beet, sweet sorghum, wheat and maize, and biodiesel from soybean, rapeseed, jatropha and oil palm. Under the IEA APS scenario, the global biofuel WF will increase more than tenfold in the period 2005–2030. The USA, China and Brazil together will contribute half of the global biofuel WF. In many countries, blue biofuel WFs significantly contribute to blue water scarcity. The research provides a first exploration of the potential contribution of transport biofuel use to blue water scarcity. In 2030, the global blue biofuel WF might have grown to 5.5% of the totally available blue water for humans, causing extra pressure on fresh water resources. When biofuel use continues to expand after 2030, countries should therefore consider the water factor when investigating the extent to which biofuels can satisfy future transport energy demand.     

Effects of the substratum on the formation of glacial tunnel valleys: an example from the Middle Pleistocene of the southern North Sea Basin

Tunnel valleys are elongated incisions formed by meltwater underneath ice sheets that rest on unlithified bed materials. The formation of tunnel valleys is commonly believed to be influenced by the properties of the preglacial bed; however, a detailed analysis of this relationship has not been performed to date. To determine whether tunnel‐valley location and morphology are controlled by the substratum, a 3D seismic survey was combined with lithological data from the Wadden Sea area in the Dutch sector of the southern North Sea Basin. This study shows that tunnel‐valley floors often coincide with seismic reflectors that mark lithological boundaries in the substratum, and that the location and depth of tunnel‐valley incision vary as a function of the properties of the substratum as expressed by lithological and geophysical‐log variations. Tunnel valleys are incised preferentially into fine‐grained layers, while the top of coarser‐grained units commonly coincide with the tunnel‐valley floor. These observations indicate that the geometry and orientation of tunnel valleys in the study area are controlled by contrasts in lithological properties of the bed. An explanation for the observed lithological control might lie in large water‐pressure differences over fine‐grained and impermeable layers along the flow‐path of subglacial meltwater flowing through the substratum, from areas with high pore‐water pressure towards areas with relatively low pressures in the vicinity of meltwater channels. These pressure differences might have been sufficient for the fracturing and fluidization of these layers. The concepts presented here have implications for existing genetic models and for the prediction of tunnel‐valley morphology in understudied areas.     

贵州新民石门坎三叠系关岭组底部火山凝灰岩锆石U-Pb年龄及意义

华南地区三叠系地层发育,安尼阶底界（即下—中三叠统界线）附近广泛发育浅绿色火山凝灰岩或凝灰质碎屑岩,俗称 “绿豆岩”。国际安尼阶底界界线层型候选剖面——位于南盘江盆地内的贵州关刀剖面和广西湾头剖面,已获得可对比的“绿豆岩”锆石U-Pb年龄,但在相邻的上扬子台地上尚缺少对安尼阶底界测年的可对比数据。本研究采集了贵州省盘州市新民镇石门坎剖面三叠系关岭组底部的多层“绿豆岩”,利用LA-ICP-MS获得锆石的U-Pb年龄。结果显示,石门坎剖面关岭组底部的锆石结晶年龄为246.9±1.1 Ma,可与南盘江盆地内及上扬子台地区出露安尼阶底界的剖面相对比。其绝对年龄为上扬子台地区内的安尼阶底界年龄对比提供了参照,有助于限定中三叠世海生爬行动物群所代表的海洋生态系统的复苏时间。石门坎剖面地层沉积连续,未来有望继续开展综合地层学的研究。     

Timing and pace of ice-sheet withdrawal across the marine–terrestrial transition west of Ireland during the last glaciation

Understanding the pace and drivers of marine-based ice-sheet retreat relies upon the integration of numerical ice-sheet models with observations from contemporary polar ice sheets and well-constrained palaeo-glaciological reconstructions. This paper provides a reconstruction of the retreat of the last British–Irish Ice Sheet (BIIS) from the Atlantic shelf west of Ireland during and following the Last Glacial Maximum (LGM). It uses marine-geophysical data and sediment cores dated by radiocarbon, combined with terrestrial cosmogenic nuclide and optically stimulated luminescence dating of onshore ice-marginal landforms, to reconstruct the timing and rate of ice-sheet retreat from the continental shelf and across the adjoining coastline of Ireland, thus including the switch from a marine- to a terrestrially-based ice-sheet margin. Seafloor bathymetric data in the form of moraines and grounding-zone wedges on the continental shelf record an extensive ice sheet west of Ireland during the LGM which advanced to the outer shelf. This interpretation is supported by the presence of dated subglacial tills and overridden glacimarine sediments from across the Porcupine Bank, a westwards extension of the Irish continental shelf. The ice sheet was grounded on the outer shelf at ~26.8 ka cal bp with initial retreat underway by 25.9 ka cal bp. Retreat was not a continuous process but was punctuated by marginal oscillations until ~24.3 ka cal bp. The ice sheet thereafter retreated to the mid-shelf where it formed a large grounding-zone complex at ~23.7 ka cal bp. This retreat occurred in a glacimarine environment. The Aran Islands on the inner continental shelf were ice-free by ~19.5 ka bp and the ice sheet had become largely terrestrially based by 17.3 ka bp. This suggests that the Aran Islands acted to stabilize and slow overall ice-sheet retreat once the BIIS margin had reached the inner shelf. Our results constrain the timing of initial retreat of the BIIS from the outer shelf west of Ireland to the period of minimum global eustatic sea level. Initial retreat was driven, at least in part, by glacio-isostatically induced, high relative sea level. Net rates of ice-sheet retreat across the shelf were slow (62–19 m a⁻¹) and reduced (8 m a⁻¹) as the ice sheet vacated the inner shelf and moved onshore. A picture therefore emerges of an extensive BIIS on the Atlantic shelf west of Ireland, in which early, oscillatory retreat was followed by slow episodic retreat which decelerated further as the ice margin became terrestrially based. More broadly, this demonstrates the importance of localized controls, in particular bed topography, on modulating the retreat of marine-based sectors of ice sheets.     

Concentration of polybrominated diphenyl ethers (PBDEs) in sediment cores of Sundarban mangrove wetland, northeastern part of Bay of Bengal (India)

The paper presents the first comprehensive survey of congener profiles (12 congeners) of polybrominated diphenyl ethers (PBDEs) in core sediment samples (<63 microm) covering seven sites in Sundarban mangrove wetland (India). Gas-chromatographic analyses were carried out in GC-Ms/Ms for tri- to hepta- brominated congeners. Results pointed out a non-homogenous contamination of the wetland with summation operator(12) PBDE values ranging from 0.08 to 29.03 ngg(-1), reflecting moderate to low contamination closely in conformity to other Asian aquatic environments. The general order of decreasing congener contribution to the total load was: BDE 47>99>100>154, similar to the distribution pattern worldwide. Although tetrabromodiphenyl ether BDE 47 was found in all samples followed by hexabromodiphenyl ether BDE-154, they were not necessarily the dominant congeners. No uniform temporal trend on PBDE levels was recorded probably due to particular hydrological characteristics of the wetland and/on non-homologous inputs from point sources (untreated municipal wastewater and local industries, electronic wastes from the dump sites, etc.) of these compounds. Because of the propensity of PBDEs to accumulate in various compartments of wildlife and human food webs, evaluation of biological tissues should be undertaken as a high priority.     

Effects of acoustic alarms, designed to reduce small cetacean bycatch in gillnet fisheries, on the behaviour of North Sea fish species in a large tank

World-wide many cetaceans drown incidentally in fishing nets. To reduce the unwanted bycatch in gillnets, pingers (acoustic alarms) have been developed that are attached to the nets. In the European Union, pingers will be made compulsory in some areas in 2005 and in others in 2007. However, pingers may effect non-target marine fauna such as fish. Therefore in this study, the effects of seven commercially-available pingers on the behaviour of five North Sea fish species in a large tank were quantified. The species tested were: sea bass (Dicentrarchus labrax), pout (Trisopterus luscus), thicklip mullet (Chelon labrosus), herring (Clupea harengus), and cod (Gadus morhua). The fish were housed as single-species schools of 9-13 individuals in a tank. The behaviour of fish in quiet periods was compared with their behaviour during periods with active pingers. The results varied both between pingers and between fish species. Sea bass decreased their speed in response to one pinger and swam closer to the surface in response to another. Thicklip mullet swam closer to the bottom in response to two pingers and increased their swimming speed in response to one pinger. Herring swam faster in response to one pinger, and pout and cod (close relatives) showed no behavioural responses to any of the pingers. Of the seven pingers tested, four elicited responses in at least one fish species, and three elicited no responses. Whether similar responses would be elicited in these fish species in the wild, and if so, whether such responses would influence the catch rate of fisheries, cannot be derived from the results of this study. However, the results indicate the need for field studies with pingers and fish. Based on the small number of fish species tested, the present study suggests that the higher the frequency of a pinger, the less likely it is to affect the behaviour of marine fish.     

New insights from age determination on toxic element accumulation in striped and bottlenose dolphins from Atlantic and Mediterranean waters

This study aimed at comparing toxic element (Hg, Cd) bioaccumulation in relation to age for bottlenose (Tursiops truncatus) and striped dolphins (Stenella coeruleoalba) from Mediterranean and Atlantic waters. Metal concentrations were also measured in selected prey to infer metal exposure through the diet. As expected, Mediterranean prey exhibited the highest Hg levels, probably as a consequence of the Hg enrichment of the Mediterranean Sea. Comparing the predators from each area and taking age into account, Mediterranean bottlenose dolphins displayed higher Hg levels than Atlantic dolphins (p = 0.032), whereas Mediterranean striped dolphins did not (p = 0.691). The consumption of Myctophid fish, which showed the highest Hg levels (105+/-80 ngg(-1) w.wt.) among Atlantic prey, may explain the high Hg levels in the liver of the Atlantic striped dolphins and suggested a preferential offshore feeding behaviour in this area. Concerning Cd, no clear differences were found between geographical areas.     

Sérsiclets – a matched filter extension of Shapelets for weak lensing studies

The precision study of dark matter using weak lensing by large-scale structure is strongly constrained by the accuracy with which one can measure galaxy shapes. Several methods have been devised but none has demonstrated the ability to reach the level of precision required by future weak lensing surveys. In this paper, we explore new avenues to the existing 'Shapelets' approach, combining a priori knowledge of the galaxy profile with the power of orthogonal basis function decomposition. This paper discusses the new issues raised by this matched filter approach and proposes promising alternatives to shape measurement techniques. In particular, it appears that the use of a matched filter (e.g. Sérsic profile) restricted to elliptical radial fitting functions resolves several well-known Shapelet issues.     

NGC 2587: a sparse open cluster projected on to a populous star field

We present CCD photometry in the Johnson U , B and V and Kron–Cousins I passbands for the open cluster NGC 2587. The sample consists of 4406 stars reaching down to   V ∼ 21.0  . We developed a new method to clean statistically the colour–magnitude diagrams. NGC 2587 appears to be a sparse, relatively bright open cluster, with a few tens of members projected on to a populous star field. The comparatively bright F7/8 II type star HD 70927, located close to the cluster centre, seems not to be a member. Our analysis suggests that NGC 2587 is slightly younger than the Hyades and probably of solar metallicity. A cluster radius of roughly 8 arcmin was estimated from the radial stellar density profile. From 18 probable cluster members with measured proper motions, we derive the following mean values for NGC 2587:  μ_α=−4.3 ± 3.6 mas yr⁻¹  and  μ_δ=−2.5 ± 3.4 mas yr⁻¹  . Adopting the theoretical metal content   Z = 0.02  , which provides the best global fit, we derive a cluster age of  500⁺⁶⁰₋₅₀  . Simultaneously, colour excesses   E ( B − V ) = 0.10  and   E ( V − I ) = 0.15  and an apparent distance modulus of   V − M_V = 12.50  are obtained. The interstellar extinction in the cluster direction is found to follow the normal law. NGC 2587 is located at a distance of (2.70 ± 0.70) kpc from the Sun and ∼9.8 kpc from the Galactic centre.