Ocean urea fertilization for carbon credits poses high ecological risks

The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed.     

Temporal sampling strategies and uncertainty in calibrating a conceptual hydrological model for a small boreal catchment

How much data is needed for calibration of a hydrological catchment model? In this paper we address this question by evaluating the information contained in different subsets of discharge and groundwater time series for multi‐objective calibration of a conceptual hydrological model within the framework of an uncertainty analysis. The study site was a 5·6‐km² catchment within the Forsmark research site in central Sweden along the Baltic coast. Daily time series data were available for discharge and several groundwater wells within the catchment for a continuous 1065‐day period. The hydrological model was a site‐specific modification of the conceptual HBV model. The uncertainty analyses were based on a selective Monte Carlo procedure. Thirteen subsets of the complete time series data were investigated with the idea that these represent realistic intermittent sampling strategies. Data subsets included split‐samples and various combinations of weekly, monthly, and quarterly fixed interval subsets, as well as a 53‐day ‘informed observer’ subset that utilized once per month samples except during March and April—the months containing large and often dominant snow melt events—when sampling was once per week. Several of these subsets, including that of the informed observer, provided very similar constraints on model calibration and parameter identification as the full data record, in terms of credibility bands on simulated time series, posterior parameter distributions, and performance indices calculated to the full dataset. This result suggests that hydrological sampling designs can, at least in some cases, be optimized. Copyright © 2009 John Wiley & Sons, Ltd.     

Radio–optical alignments in a low radio luminosity sample

We present an optically based study of the alignment between the radio axes and the optical major axes of eight z ∼0.7 radio galaxies in a 7C sample. The radio galaxies in this sample are ≈20 times less radio‐luminous than 3C galaxies at the same redshift, and are significantly less radio-luminous than any other well-defined samples studied to date. Using Nordic Optical Telescope images taken in good seeing conditions at rest frame wavelengths just longward of the 4000-Å break, we find a statistically significant alignment effect in the 7C sample. Furthermore, in two cases where the aligned components are well separated from the host we have been able to confirm spectroscopically that they are indeed at the same redshift as the radio galaxy. However, a quantitative analysis of the alignment in this sample and in a corresponding 3C sample from HST archival data indicates that the percentage of aligned flux may be lower and of smaller spatial scale in the 7C sample. Our study suggests that alignments on the 50-kpc scale are probably closely related to the radio luminosity, whereas those on the 15‐kpc scale are not. We discuss these results in the context of popular models for the alignment effect.     

The DNSC08GRA global marine gravity field from double retracked satellite altimetry

Satellite radar altimetry has been monitoring the earth’s oceans from space for several decades. However, only the GEOSAT and ERS-1 geodetic mission data recorded more than a decade ago provide altimetry with adequate spatial coverage to derive a high-resolution marine gravity field. The original geodetic mission data suffer from degradation in quality and coverage close to the coast and in Polar Regions as well as the occasionally wrongly retracking of these, even in the open ocean. In order to improve the quality of these geodetic mission data and to derive a new improved global marine gravity field called DNSC08GRA, a new double retracking technique for analyzing the waveform data has been developed. Multiple retracking allows the system to retrack more data to increase the spatial coverage of the data. Subsequently, a second retracking run is used to enhance the SSH determination by using information from the first fitting to inform the second set of retrackers about smoothly varying sea state parameters. The development of the new global marine gravity field DNSC08GRA is described in this paper. Besides application of new retracking techniques the radar altimetry has been processed using EGM2008 as reference and augmented with ArcGP gravity data and laser altimetry from ICESat to close the Polar gap. DNSC08GRA is seen to perform significantly better than previous global marine gravity field like KMS02. The improvement in accuracy is better than 20% in general, but in coastal regions, the improvement is in many places of the order of 40–50% compared to older global marine gravity field KMS02.     

An event stratigraphy for the Last Termination in the North Atlantic region based on the Greenland ice-core record: a proposal by the INTIMATE group

It is suggested that the GRIP Greenland ice-core should constitute the stratotype for the Last Termination. Based on the oxygen isotope signal in that core, a new event stratigraphy spanning the time interval from ca. 22.0 to 11.5 k GRIP yr BP (ca. 19.0–10.0 k ¹⁴C yr BP) is proposed for the North Atlantic region. This covers the period from the Last Glacial Maximum, through Termination 1 of the deep-ocean record, to the Pleistocene–Holocene boundary, and encompasses the Last Glacial Late-glacial of the traditional northwest European stratigraphy. The isotopic record for this period is divided into two stadial episodes, Greenland Stadials 1 (GS-1) and 2 (GS-2), and two interstadial events, Greenland Interstadials 1 (GI-1) and2 (GI-2). In addition, GI-1 and GS-2 are further subdivided into shorter episodes. The event stratigraphy is equally applicable to ice-core, marine and terrestrial records and is considered to be a more appropriate classificatory scheme than the terrestrially based radiocarbon-dated chronostratigraphy that has been used hitherto. © 1998 John Wiley & Sons, Ltd.     

Bioavailability of PAH in effluent water from an aluminium works evaluated by transplant caging and biliary fluorescence measurements of Atlantic cod (Gadus morhua L.)

Fixed wavelength fluorescence (FF) of bile was used as a biomarker for PAH exposure in fish caged adjacent to an aluminium works. After 30 days of caging, a 20–50 fold increase of pyrene fluorescence was found in groups caged adjacent to the works as compared to two control groups. The PAH uptake occurred mainly from suspended particles rather than from PAH contaminated sediments at the caging sites. Our results demonstrates the combined use of fish caging and bile-fluorescence measurements as a powerful field model for the monitoring of coastal waters subjected to PAH pollution.     

Larval dispersal and vertical migration behaviour – a simulation study for short dispersal times

Current speed often varies with depth, so vertical movements of larvae are expected to have profound effects on dispersal velocity and therefore dispersal potential. Systematic behaviours are expected to have strong effects on dispersal. However, reliable information on the presence of vertical migrations in larvae is scarce, but the few well investigated empirical examples justify a detailed simulation study and an analysis of potential effects. We present a spatially explicit 3D hydrodynamic model that incorporates biological information in the form of active particles advected in a Lagrangian fashion. The set‐up is designed to analyze the sensitivity of dispersal distances to variation in vertical behaviour of larvae. We simulated short (4 days) pelagic larval durations (PLDs) to determine whether behaviour might be important over short dispersal periods. We found that sinusoidal behaviours (slow vertical migration) in or out of phase with tides did not significantly change the dispersal patterns compared to those of larvae that remained at the surface. By contrast, a quadratic pattern of behaviour resulting in rapid vertical migration, in or out of phase with tides, had dramatic effects on both distance and direction of dispersal. The resulting dispersal kernels were found to be multimodal due to the interaction between tidal and meteorological components in flow. Incorporating biological information on larval migrations in Lagrangian simulation of dispersal will be important in estimates of connectivity and forecasting marine reserve networks.     

Architecture of growth basins in a tidally influenced,prodelta to delta-front setting: The Triassic succession of Kvalpynten,East Svalbard

World-class examples of fault-controlled growth basins with associated syn-kinematic sedimentary fill are developed in Upper Triassic prodelta to delta-front deposits exposed at Kvalpynten, SW Edgeøya in East Svalbard. They are interpreted to have interacted with north-westerly progradation of a regional delta system. The syn-kinematic successions consist of 4 to 5 coarsening-upward units spanning from offshore mudstones to subtidal heterolithic bars and compound tidal dunes, which were blanketed by regional, post-kinematic sandstone sheets deposited as laterally continuous, subaqueous tidal dune fields. The rate of growth faulting is reflected in the distribution of accommodation, which governs sedimentary architecture and stacking patterns within the coarsening-upward units. Fully compartmentalized basins (12, 200–800 m wide and c. 150 m high grabens and half grabens) are characterized by syn-kinematic sedimentary infill. These grabens and half-grabens are separated by 60–150 m high horsts composed of pro-delta to distal delta-front mudstones. Grabens host tabular tidal dunes (sandwaves), whereas half-grabens bound by listric faults (mainly south-dipping) consist of wedge-shaped, rotated strata with erosive boundaries proximal to the uplifted fault block crests. Heterolithic tidal bars (sand ridges) occur in narrow half-grabens, showing migration oblique to the faults, up the dipslope. Structureless sandstone wedges and localized subaqueous slumps that formed in response to collapse of the block crests were only documented in half-grabens. Late-kinematic deposition during the final stages of faulting occurred in partly compartmentalized basins, filled with variably thick sets of continuous sandstone belts (compound tidal dunes).     

Application of CCSEM to heavy mineral deposits: Source of high-Ti ilmenite sand deposits of South Kerala beaches, SW India

For the characterization of sediments, Computer Controlled Scanning Electron Microscopy (CCSEM) is a powerful method in obtaining chemical data on individual mineral grains and modal analysis of the heavy mineral fraction of sediment samples. Here we show how the CCSEM method can be used to evaluate ilmenite ore grade as well as a tool to investigate the source of heavy mineral deposits.The heavy mineral rich deposits in beach sands around the town of Chavara in SW India are characterized by ilmenite with elevated TiO₂ contents, often exceeding 60 wt.%. In order to determine the origin of these high-TiO₂ ilmenite deposits, we collected a series of beach sediment samples (22) from a c. 800 km long stretch of coastline from northern Kerala state to well within the Tamil Nadu state. A set (7) of river sediments was also taken, roughly covering the catchment area to the beach samples. The data show that the sediments in the Chavara high-Ti ilmenite deposit are distinguished by minor elements in ilmenite, garnet chemistry and heavy mineral assemblage: Chavara ilmenite has high MgO and low MnO contents; garnets have low grossular components and the heavy mineral assemblage is dominated by sillimanite–kyanite in addition to ilmenite. These features correlate with basement geology in the hinterland, and with sediments from rivers, draining the basement. Based on these observations we conclude that high-Ti ilmenite from Chavara beaches originates in the khondalite belt of high-grade metasediments. Our study demonstrates rapid mineral analyses in sediments by CCSEM to be efficient in the characterization of mineral compositions and assemblages in sediments, in the identification of possible source regions and thus ultimately in exploration for industrial mineral resources.     

Civilian GPS: The Benefits of Three Frequencies

A third civil frequency at 1176.45 MHz will be added to the Global Positioning System (GPS). This new frequency will bring a number of benefits. The aviation user will be one of the prime beneficiaries because the new frequency is in a protected aviation band. Thus, the system will be more robust against interference and jamming. The carrier-phase differential user will also be a prime beneficiary as long as his application has a reasonably short baseline. It is this high accuracy use that is explored in some depth. The process of forming linear combinations of both the code and carrier-phase measurements is studied, and the benefits and problems are explained. ? 2000 John Wiley & Sons, Inc.