A retrospective analysis of contamination and periphyton PICT patterns for the antifoulant irgarol 1051, around a small marina on the Swedish west coast

Irgarol is a triazine photosystem II (PSII) inhibitor that has been used in Sweden as an antifouling ingredient since the 1990s. Early microcosm studies indicated that periphyton was sensitive to irgarol at concentrations regularly found in harbours and marinas. However, field studies of irgarol effects on the Swedish west coast in 1994, using the pollution-induced community tolerance (PICT) approach, failed to detect any effects of the toxicant in the field. A PICT study involves sampling of replicate communities in a gradient of contamination, and a comparison of their community tolerance levels, with an increase being an indication that sensitive species have been eliminated and replaced by more tolerant ones. Typically, short-term assays are used to quantify the community tolerance levels. Later PICT studies in the same area over a 10 year period demonstrate that irgarol tolerance levels have increased, although the contamination pattern has been stable. Our results support the hypothesis that that the PICT potential was low initially, due to a small differential sensitivity between the community members, and that a persistent selection pressure was required to favour and enrich irgarol-tolerant species or genotypes.     

Solar magnetic activity: topology and prediction

We ascribe the solar magnetic activity to the interplay between the plasma flow and the magnetic field. Observations by SOHO, Hinode and upcoming SDO are discussed. We then discuss the understanding and modeling of solar magnetic activity based on mathematical topological concepts. We present predictions using neural networks. Further we describe the outcome of the cycle 24 prediction panel. Finally, recommendations are given for making improved predictions.     

Short contribution: Mapping quaternary deposits as a method for explaining the distribution of mesolithic sites in reclaimed landscapes: An example from Vålse Vig,southeast Denmark

Archaeological sites dating to the Ertebolle period of the Mesolithic have been recorded below a thin layer of marine sands in a reclaimed bay on northern Falster Island in Denmark. The finds seemed randomly distributed throughout the bay; there was no obvious pattern related to the modern landscape. However, by coring through the veneer of marine sands and mapping the pattern of the underlying Late Quaternary deposits, the authors were able to reconstruct the Mesolithic landscape and thereby explain the distribution of archaeological sites. This approach allows archaeologists to focus subsurface exploration in geomorphic settings, such as former fjords and coastlines that have a high potential for yielding prehistoric sites. © 2006 Wiley Periodicals, Inc.     

Influence of interplanetary interaction regions on geomagnetic disturbances and tropospheric circulation

Proposed solar wind-magnetosphere energy coupling functions are studied. An empirical formula proposed by Svalgaard (1977) is found to predict the geomagnetic activity quite well.

The influence of solar wind interaction regions on the tropospheric circulation, through a suggested cosmic ray mechanism, was investigated. The cosmic ray intensity at Earth clearly showed a decrease at the time of passage of an interaction region. It is suggested that the well-known dip in the Vorticity Area Index may be caused by an interaction-modulated decrease in cosmic ray intensity.     

The Greenland Ice Core Chronology 2005, 15–42 ka. Part 2: comparison to other records

A new Greenland Ice Core Chronology (GICC05) based on multi-parameter counting of annual layers has been obtained for the last 42 ka. Here we compare the glacial part of the new time scale, which is based entirely on records from the NorthGRIP ice core, to existing time scales and reference horizons covering the same period. These include the GRIP and NorthGRIP modelled time scales, the Meese-Sowers GISP2 counted time scale, the Shackleton–Fairbanks GRIP time scale (SFCP04) based on ¹⁴C calibration of a marine core, the Hulu Cave record, three volcanic reference horizons, and the Laschamp geomagnetic excursion event occurring around Greenland Interstadial 10. GICC05 is generally in good long-term agreement with the existing Greenland ice core chronologies and with the Hulu Cave record, but on shorter time scales there are significant discrepancies. Around the Last Glacial Maximum there is a more than 1 ka age difference between GICC05 and SFCP04 and a more than 0.5 ka discrepancy in the same direction between GICC05 and the age of a recently identified tephra layer in the NorthGRIP ice core. Both SFCP04 and the tephra age are based on ¹⁴C-dated marine cores and fixed marine reservoir ages. For the Laschamp event, GICC05 agrees with a recent independent dating within the uncertainties.     

Particle Size Distributions of Clay-rich Sediments and Pure Clay Minerals: A Comparison of Grain Size Analysis with Sedimentation Field-Flow Fractionation

Two clay-rich coastal sediment samples have been characterised together with three pure clays identified as major components of the sediment samples. The mineralogy of the sediments was determined by X-ray diffraction, and their bulk properties measured (organic carbon content, leachable iron and manganese, surface area and cation exchange capacity). A simple approach is used to model the properties of the sediments from those of their pure clay components. Good agreement is found for cation exchange capacity and specific surface area indicating that the clay minerals are the most important constituents influencing the sediments' surface properties. Particle size distributions were assessed by conventional grain size analysis, and also by Sedimentation Field-Flow Fractionation (SedFFF). These two approaches yield sharply differing size distributions; in particular, conventional grainsize analysis indicates a much greater proportion of submicron particles. Similar results are obtained from analysis of pure clays. The most likely reason for this is artifacts introduced in the unavoidable 1 m prefractionation used for SedFFF.     

Assessing climate change impacts on the Iberian power system using a coupled water-power model

Climate change is expected to have a negative impact on the power system of the Iberian Peninsula; changes in river runoff are expected to reduce hydropower generation, while higher temperatures are expected to increase summer electricity demand, when water resources are already limited. However, these impacts have not yet been evaluated at the peninsular level. We coupled a hydrological model with a power market model to study three impacts of climate change on the current Iberian power system: changes in hydropower production caused by changes in precipitation and temperature, changes in temporal patterns of electricity demand caused by temperature changes, and changes in irrigation water use caused by temperature and precipitation changes. A stochastic dynamic programming approach was used to develop operating rules for the integrated system given hydrological uncertainty. We found that changes in precipitation will reduce runoff, decrease hydropower production (with accompanying increases in thermal generation), and increase irrigation water use, while higher temperatures will shift power demand from winter to summer months. The combined impact of these effects will generally make it more challenging to balance agricultural, power, and environmental objectives in the operation of Iberian reservoirs, though some impacts could be mitigated by better alignment between temporal patterns of irrigation and power demands.     

Initial design of urban drainage systems for extreme rainfall events using intensity–duration–area (IDA) curves and Chicago design storms (CDS)

ABSTRACT

Due to more frequent extreme rainfall incidents in recent years, many large cities are considering the construction of new drainage systems to cope with rainfall in the order of 100-year events. In such cases, T-year point rainfall events should be supplemented with areal reduction factors (ARF) to avoid overdesign. To facilitate an initial design, a procedure based on using Chicago Design Storms (CDS) in combination with intensity–duration–area (IDA) curves was developed to produce CDS-ARF input rainfall. By means of the time of concentration, a specific instantaneous unit hydrograph (IUH) was obtained for each subcatchment. Combination of CDS-ARF rains and the subcatchment IUHs using convolution integrals was used to produce inflow hydrographs to the drainage system. A sequential design procedure that successively includes subcatchments for the entire drainage system in the downstream direction is implemented and exemplified ensuring a consistent initial design.     

Short-range order in tourmaline: a vibrational spectroscopic approach to elbaite

Polarized Fourier-transform infrared and Raman spectra were acquired on an elbaite sample previously characterized by electron- and ion microprobe analysis, X-ray diffraction and structure refinement. Spectra from the two vibrational spectroscopy techniques reveal a close similarity in the OH-stretching region, with three main absorption bands strongly polarized in the c-axis direction. By means of bond-valence theory arguments, the observed OH bands are interpreted and assigned to specific local cation arrangements around the O1 (≡W) and O3 (≡V) anion sites. In combination with the relatively simple composition of the studied sample, bond-valence constraints are used to identify stable anion-cation arrangements, which permit the occurrence of short-range ordering to be assessed. Evidence for nearly complete short-range order at the O1 site, with the stable arrangements ^Y(LiAlAl)_0.6–^W(OH)_0.6 and ^Y(LiLiAl)_0.4–^W(F)_0.4, are presented. These two local arrangements can be further expanded to obtain the larger ordered clusters [^W(OH)–^Y(LiAl₂)–^V(OH)₃–^Z(Al)₆]_0.6 and [^W(F)–^Y(Li₂Al)–^V(OH)₃–^Z(Al)₆]_0.4.