Peat bank growth,Holocene palaeoecology and climate history of South Georgia (sub-Antarctica), based on a botanical macrofossil record

Botanical macrofossil analysis of a more than 9000 years old, radiocarbon dated peat sequence of a moss peat bank from South Georgia, shows a clear evolution in the vegetation. Seven ecological phases could be distinguished and they can be interpreted in terms of climate development during the Holocene. Until 2200 years ago, Warnstorfia fontinaliopsis was the dominant moss species pointing to a wet environment. Lower numbers of this species in association with the presence of drier species are assumed to indicate drier periods, such as occurring between ca 6000–5200 and 4400–3400 cal yr BP. The most prominent and definitive vegetation change took place around 2200 cal yr BP. A Polytrichum–Chorisodontium moss peat bank was formed, which is still growing there today. The forcing mechanism for this vegetation change is thought to be a temperature decrease, rather than a precipitation decrease. This conclusion is mainly based on the fact that, today, moss peat banks have their optimal occurrence range in the maritime Antarctic, a region were the mean annual temperature is ca 4 °C lower than on South Georgia. The remarkable change in the moss bank vegetation at 2200 cal yr BP raises the question whether this moment was only a short climatic deterioration, or a definitive change to a cooler and wetter climate after a Holocene climatic optimum period.     

Does upward seepage of river water and storm water runoff determine water quality of urban drainage systems in lowland areas? A case study for the Rhine–Meuse delta

The water quality of urban drainage ditches in lowlands in the Rhine‐Meuse delta was analysed with principal component analysis (PCA) during a dry period and a rain storm, and related to the seepage of polluted river water and effective impervious area (EIA). This was done in order to test the hypothesis that seepage of river water and storm water runoff from impervious areas strongly determine the water quality of urban drainage systems along large lowland rivers. Our analysis revealed that upward seepage of groundwater originating from rivers Rhine and Meuse was positively correlated with nitrate, potassium, sodium and chloride and negatively correlated with alkalinity, calcium, magnesium and iron. EIA was correlated with very few environmental variables (i.e. phosphate, pH and iron in the dry period and iron during the rain storm). Nickel and zinc concentrations generally exceeded the maximum allowable concentrations (MAC), while lead and phosphorus concentrations were just above the nutrient standards and MAC in a few locations during the rain storm. To optimize water quality in urban water systems, attention should be paid to all sources of pollution and not only to EIA. The impact of local groundwater seepage originating from large rivers in lowlands on the chemistry of urban water systems is often underestimated and should be taken into account when assessing water quality and improving water quality status. Copyright © 2009 John Wiley & Sons, Ltd.     

Evidence of Traveling Waves in Filament Threads

High-resolution Hα filtergrams (0.2″) obtained with the Swedish 1-m Solar Telescope resolve numerous very thin, thread-like structures in solar filaments. The threads are believed to represent thin magnetic flux tubes that must be longer than the observable threads. We report on evidence for small-amplitude (1 – 2 km s⁻¹) waves propagating along a number of threads with an average phase velocity of 12 km s⁻¹ and a wavelength of 4″. The oscillatory period of individual threads vary from 3 to 9 minutes. Temporal variation of the Doppler velocities averaged over a small area containing a number of individual threads shows a short-period (3.6 minutes) wave pattern. These short-period oscillations could possibly represent fast modes in accordance with numerical fibril models proposed by Díaz et al. (Astron. Astrophys. 379, 1083, 2001). In some cases, it is clear that the propagating waves are moving in the same direction as the mass flows.     

Diet and gill morphology of the East Coast redeye round herring Etrumeus wongratanai off KwaZulu-Natal,South Africa

Stomach content analyses and measurements of gillraker morphology were used to assess the diet and feeding ecology of the East Coast redeye round herring Etrumeus wongratanai and provide data for comparisons with other small pelagic fishes off South Africa. Samples were collected by jigging from a kayak off Scottburgh, KwaZulu-Natal (KZN), over the period July 2013–May 2014. In total, 66 stomachs (containing 4 407 prey items) and 66 gill arches were examined. Stomach content analyses indicated that East Coast redeye round herring, at the time of sampling, fed on large (1 500–2 500?µm) particles, with ～2 500?µm particles making the greatest contribution to dietary carbon. The species feeds on larger particles than do anchovy Engraulis encrasicolus and sardine Sardinops sagax, but on particles of a similar size to those consumed by West Coast redeye round herring Etrumeus whiteheadi. There were significant differences in mean gillraker gaps between East Coast redeye round herring and both sardine and anchovy, but not between East Coast and West Coast redeye round herring. The differences in gillraker gaps between East Coast redeye round herring, sardine and anchovy are indicative of resource partitioning through differential feeding, based on zooplankton size. The data suggest that there is no resource partitioning between East and West coast redeye round herring, indicating that competition is likely to occur between them. However, such competition is minimised by limited spatial overlap between these two species.     

Evidence for surface variegation in Rosetta OSIRIS images of asteroid 2867 Šteins

The OSIRIS camera onboard Rosetta successfully acquired images of asteroid 2867 Steins through a variety of color filters during the flyby on 5 September 2008. The best images of this 5 km diameter asteroid have a resolution of 78 m per pixel. We process the images by deconvolving with the point spread function and enlarging through the Mitchell-Netravali filter. The enhanced set is analyzed by means of various techniques (PCA, band ratios, stereo anaglyphs) to study surface morphology and search for variegation. We identify a landslide, which supports a YORP origin for Steins’ unusual diamond shape. In addition, we find that the interior of one of two large craters on the south pole is bluer than the rest of the body.     

Mobility of metals in nickel mine spoil materials

An understanding of the biogeochemical behaviour of metals in mine spoil materials is a prerequisite to rehabilitate Ni mining sites. The objective of this study was to characterize the fate of metals in different Ni ore spoil materials as influenced by hydrological conditions and fertilisation practices. In tropical ultramafic complexes, the different stages of lateritic weathering lead to two types of ores, and therefore, to two spoil types. They are mainly either a clay-rich saprolite, so-called “garnierite”, enriched in phyllosilicates, or a limonitic material, enriched in Fe oxides. Lysimeter columns were designed to monitor leaching waters through both spoil materials. The garnieritic spoil released higher concentrations of Mg (mean = 2.25 mg L⁻¹), Ni (0.39 mg L⁻¹) and Cr (1.19 mg L⁻¹) than the limonitic spoil (Mg = 0.5 mg L⁻¹; Ni = 0.03 mg L⁻¹ and Cr = 0.25 mg L⁻¹). Chromium was mainly in an anionic form in leaching solutions. As exchangeable pools of Cr(VI) in limonite (980 mg kg⁻¹ of KH₂PO₄-extractable Cr) are considerable its release in water may still occur in the case of a pH increase. In mixed spoil, metal concentrations were almost as low as in the limonitic one. The effect of mineral-N fertilisation was a strong release of cations (Ni, Mg) into the leachate. Phosphate amendment did not affect the soil solution composition under experimental conditions.