Suspension and calibration of a sediment trap

The aim of this technical note is to introduce a new, simple construction of a buoy-carried, suspended sediment trap that meets given demands concerning design (geometry of vessels) and stability during the registration period. The device is based on a ball-and-socket joint in the center and two Plexiglas cylinders (D=5cm, H=30cm) on PVC plastic arms. The suspension consists of only three parts. To determine the optimal construction, the apparatus has been calibrated in a circulating flume at various water velocities.     

Zircon coronas around Fe–Ti oxides: a physical reference frame for metamorphic and metasomatic reactions

Ilmenite in coronitic gabbros from the Bamble and Kongsberg sectors, southern Norway, is surrounded by zircons ranging in diameters from a fraction of a micrometer to 10 μm across. The zircons are inert during subsequent metamorphism (amphibolite- to pumpellyite–prehnite facies) and metasomatism (scapolitization and albitization) and can be found as trails in silicates (phlogopite, talc, chlorite, amphibole, albite, and tourmaline) in the altered rocks. The trails link up to form polygons outlining the former oxide grain boundary. This 3-dimensional framework of zircons is used to (a) recognize metasomatic origin of rocks, (b) quantify the mobility of elements during mineral replacement, (c) establish the growth direction of reaction fronts and to identify the reaction mechanism as dissolution–reprecipitation. Zircon coronas on Fe–Ti oxides have been described from a number of terrains and appear to be common in mafic rocks (gabbros and granulites) providing a tool for a better understanding of metasomatic and metamorphic reactions.     

Turbidity-discharge hysteresis in a meso-scale catchment: The importance of intermediate scale events

In-situ sensors for riverine water quality monitoring are a powerful tool to describe temporal variations when efficient and informative analyses are applied to the large quantities of data collected. Concentration-discharge hysteresis patterns observed during storm events give insights into headwater catchment processes. However, the applicability of this approach to larger catchments is less well known. Here, we evaluate the potential for high-frequency turbidity-discharge (Q) hysteresis patterns to give insights into processes operating in a meso-scale (722 km²) northern mixed land use catchment. As existing event identification methods did not work, we developed a new, objective method based on hydrograph characteristics and identified 76 events for further analysis. Qualitative event analysis identified three recurring patterns. Events with low mean Q (≤ 2 m³/s) often showed short-term, quasi-periodic turbidity variation, to a large extent disconnected from Q variation. High max Q events (≥15 m³/s) were often associated with spring flood or snowmelt, and showed a disconnection between turbidity and Q. Intermediate Q events (mean Q: 2–11 m³/s) were the most informative when applying hysteresis indexes, since changes in turbidity and Q were actually connected. Hysteresis indexes could be calculated on a subset of 60 events, which showed heterogeneous responses: 38% had a clockwise response, 12% anticlockwise, 12% figure eight (clockwise–anticlockwise), 10% reverse figure eight (anticlockwise–clockwise) and 28% showed a complex response. Clockwise hysteresis responses were associated with the wetter winter and spring seasons. Generally, changes in Q and turbidity were small during anticlockwise hysteresis events. Precipitation often influenced figure-eight patterns, while complex patterns often occurred during summer low flows. Analysis of intermediate Q events can improve process understanding of meso-scale catchments and possibly aid in choosing appropriate management actions for targeting a specific observed pattern.     

Temperature and pressure dependence of Fe-Mg partitioning between garnet and phengite,with particular reference to eclogites

Experimental data combined with data from natural rocks have been used to calibrate a geothermometer based on the distribution of Fe²⁺ and Mg between coexisting garnets and phengites. The pressure effect on the K _D -value appears to be considerable. The calculated thermometer is expressed as $$T(K) = \frac{{3685 + 77.1P(kb)}}{{InK_D + 3.52}}.$$ The use of this \(K_{D_{(FeO/MgO)} }^{ga + ph}\) geothermometer on eclogites with low Fe₂O₃ content, gives P-T values which are in good accordance with those obtained by other methods. The problems that arise when Fe³⁺ is present in larger amounts, are discussed.     

Influence of Temporal Variations in River Discharge, pH, Alkalinity and Ca on the Speciation and Concentration of Heavy Metals in Some Mining Polluted Rivers

Dissolved (dialysis in situ) and total concentrations ofCu, Zn, Cd and Al in eight mining polluted rivers in the Røros area, central Norway, were determinedby atomic absorption spectrometry (flame and graphite furnace) and compared to pH, Caconcentration and alkalinity through seasonal variations in river discharge. Totalconcentrations of the metals were highest during early spring flood and during summer andautumn rain episodes. Dissolved concentrations also increased as the spring floodproceeded, but small discharge peaks within this 2 month period as well as a considerableautumn flood episode appeared to lower rather than to raise the dissolved metal concentrations.Consequently the dissolved fractions of Zn, Cd and Al showed a significant negative correlationwith river discharge, and were low at the discharge peaks. Possibly high sediment concentrationsoccurring at high flood conditions more than counteracted desorption induced by pHdecrease, and led to decreased dissolved fractions through adsorption. Cu speciationon the other hand seemed to be more closely linked to pH. Alkalinity and Ca concentration,both assumed to protect aquatic life from metal pollution, were significantly lowerduring episodes with high Cu and Al total concentrations.     

From Fish to Jellyfish in the Eutrophicated Limfjorden (Denmark)

The heavily eutrophicated Limfjorden (Denmark) provides a good illustration of the value of long-term monitoring, especially if this is combined with an experimental, interdisciplinary research approach. Here, we first give a short overview of the environmental status of Limfjorden, including the historical development of nutrient overloading and subsequent oxygen depletion in near-bottom water, and how the annual landings of edible bottom-dwelling fish species (plaice, flounder, eel and others) caught in Limfjorden have decreased from about 2,500 t in the early 1920s to only about 20 t in recent years where the fish have been replaced by an increasing number of especially the moon jellyfish, Aurelia aurita, which mainly preys on zooplankton. Next, we evaluate the ecological consequences of the present high number of jellyfish, based on data from recent years’ research on the abundance of jellyfish, their population dynamics and predation impact. In Limfjorden, the benthic polyp stage of A. aurita ensures a large number of small ephyrae in the early spring and subsequently a large population of adult medusae that control the zooplankton during summer and autumn. The holopelagic invasive ctenophore Mnemiopsis leidyi, which was observed in Limfjorden for the first time in 2007, is a second carnivore adding additional predation pressure of the indigenous A. aurita so that copepods and other mesozooplankton organisms may be virtually absent, as observed in 2008 and 2009 where ciliates made up a substantial part of the zooplankton biomass. Marine environmental management programmes should be aware of the increasing importance of both indigenous and new invasive jellyfish species that may show mass occurrence in especially eutrophicated and over-fished areas.     

Boron substitution in diopside evaluated through 11B nuclear reaction analysis

 Nuclear reaction analyses on boron in flux-grown Me³⁺- and Na⁺-doped diopside crystals utilising the ¹¹B(p,2α)⁴He reaction in conjunction with EMP analyses for major elements and optical absorption spectroscopy for determination of Me-valence state distributions show that appreciable amounts of B may enter the diopside lattice in crystals produced in Na₂B₄O₇ fluxes. The results indicate that the substitution ^[6]Me^3+[4]B^3+[6]Mg²⁺ ₋₁ ^[4]Si⁴⁺ ₋₁ operates in the present diopside samples in addition to the coupled substitution ^[6]Me^3+[8]Na^+[6]Mg²⁺ ₋₁ ^[8]Ca²⁺ ₋₁. The specific NRA technique applied allows for quantitative, high resolution (ca. 5 μm) B analyses at ppm level as well as high-resolution and high-contrast imaging of B-concentration patterns in minerals. The estimated detection limit and relative error of the B analyses are 10 ppm and 5–10%, respectively. Received: 20 September 1999 / Accepted: 6 June 2000     

Talc-garnet-kyanite-quartz schist from an eclogite-bearing terrane,Western Tasmania

Talc-garnet-kyanite-quartz schist occurs in an eclogite-bearing terrane in the Precambrian of Western Tasmania. It is argued that this rock was formed at a pressure of ? 10 kb and a temperature of 600°±20° C. Chemical zoning in the garnet and talc preserves evidence of increasing temperature during growth of the major minerals.     

Local traditions as a means for commercial production of historical beers: The case of Vossaøl,Norway

The aim of the article is to analyse challenges facing the commercial production of historical beers, which are ‘extinct’ beers. The concept of ‘fictive terroir’ is introduced to emphasize these challenges. The author addresses the following questions: What kind of knowledge is needed to produce historical beers? How can this knowledge be acquired? How can it be used commercially in craft breweries? The studied case is Vossaøl, a craft beer imitation of a beer produced in the early 19th century. The data were obtained from written sources and interviews with local home brewers and brewers at Voss Brewery in Norway. The study revealed the need to reconstruct the terroir in the early 19th century. Additionally, Voss Brewery had to acquire knowledge about how to process and combine the ingredients, which included the traditional yeast (kveik). Involving traditional home brewers was crucial to determine how ingredients could be combined to produce Vossaøl. The author concludes that a synthetic knowledge base was a useful point of departure in this respect. Participation in the traditional culture of brewing proved an important means when working with this knowledge base. The results are interesting in the broader context of the reconstruction of beverages and food.     

Making a home during crisis: Post‐tsunami recovery in a context of war,Sri Lanka

This paper provides insights into the dynamic linkages between the ongoing construction of houses for people displaced by war and disaster, conceptions of homemaking and processes of recovery and reconstruction in the post‐tsunami context in Sri Lanka. In so doing, it also uncovers the dilemmas and ambiguities that are embedded in the recovery process. A case from Eastern Province, Sri Lanka illustrates how recovery works in local areas are driven by various stakeholders from outside, whose negotiations and power, voices and preferences, both independently and collectively, define the scope for homemaking processes. Our findings recommend that debates of ‘building back better’ following such disasters should embody an understanding of houses as political, cultural, social and economic constructs, and be cognizant of the wider processes of homemaking.