ALBERT

Beschreibung: Paul Baird and Mohammad Wehbe Given a Riemannian 3-manifold (M, g) endowed with a unit vector field U that is tangent to a conformal foliation, we require that the pair extend to a space-time ([script M],[script G]) endowed with a space-like unit vector field U in such a way that U simultaneously generates null geodesics and is ... [J. Math. Phys. 53, 032504 (2012)] published Thu Mar 8, 2012.

Beschreibung: Effects of seawater p CO 2 changes on the calcifying fluid of scleractinian corals Biogeosciences Discussions, 9, 2655-2689, 2012 Author(s): S. Hohn and A. Merico Rising atmospheric CO 2 concentrations due to anthropogenic emissions induce changes in the ocean carbonate chemistry and a drop in ocean pH. This acidification process is expected to harm calcifying organisms like coccolithophores, molluscs, echinoderms, and corals. A severe decline in coral abundance is, for example, expected by the end of this century with associated disastrous effects on reef ecosystems. Despite the growing importance of the topic, little progress has been made with respect to modelling the impact of acidification on coral calcification. Here we present a model for a coral polyp that simulates the carbonate system in four different compartments: the seawater, the polyp tissue, the coelenteron, and the calicoblastic layer. Precipitation of calcium carbonate takes place in the metabolically controlled calicoblastic layer beneath the polyp tissue. The model is adjusted to a state of activity as observed by direct microsensor measurements in the calcifying fluid. Simulated CO 2 perturbation experiments reveal decreasing calcification rates under elevated p CO 2 despite strong metabolic control of the calcifying fluid. Diffusion of CO 2 through the tissue into the calicoblastic layer increases with increasing seawater p CO 2 leading to decreased aragonite saturation in the calcifying fluid of the coral polyp. Our modelling study provides important insights into the complexity of the calcification process at the organism level and helps to quantify the effect of ocean acidification on corals.

Beschreibung: The role of the seagrass Posidonia oceanica in the cycling of trace elements Biogeosciences Discussions, 9, 2623-2653, 2012 Author(s): C. Sanz-Lázaro, P. Malea, E. T. Apostolaki, I. Kalantzi, A. Marín, and I. Karakassis The aim of this work was to study the role of the seagrass Posidonia oceanica on the cycling of a wide set of trace elements (Ag, As, Ba, Bi, Cd, Co, Cr, Cs, Cu, Fe, Ga, Li, Mn, Ni, Pb, Rb, Sr, Tl, V and Zn). We measured the concentration of these trace elements in the different compartments of P. oceanica (leaves, rhizomes, roots and epibiota) in a non-polluted seagrass meadow representative of the Mediterranean and calculated the annual budget from a mass balance. We provide novel data on accumulation dynamics of many trace elements in P. oceanica compartments and demonstrate that trace element accumulation patterns are mainly determined by plant compartment rather than by temporal variability. Epibiota was the compartment which showed the greatest concentrations for most trace elements. Thus, they constitute a key compartment when estimating trace element transfer to higher trophic levels by P. oceanica . For most trace elements, translocation seemed to be low and acropetal. Zn, Cd, Sr and Rb were the trace elements that showed the highest release rate through decomposition of plant detritus, while Cs, Tl and Bi the lowest. P. oceanica acts as a sink of potentially toxic trace elements (Ni, Cr, As and Ag), which can be sequestered, decreasing their bioavailability. P. oceanica may have a relevant role in the cycling of trace elements in the Mediterranean.

Beschreibung: Direct observations of diel biological CO 2 fixation in the oceans Biogeosciences Discussions, 9, 2153-2168, 2012 Author(s): H. Thomas, S. E. Craig, B. J. W. Greenan, W. Burt, G. J. Herndl, S. Higginson, L. Salt, E. H. Shadwick, and J. Urrego-Blanco Much of the variability in the surface ocean's carbon cycle can be attributed to the availability of sunlight, through processes such as heat fluxes and photosynthesis, which regulate over a wide range of time scales. The critical processes occurring on timescales of a day or less, however, have undergone few investigations, and most of these have been limited to a time span of several days to months, or exceptionally, for longer periods. Optical methods have helped to infer short-term biological variability, however corresponding investigations of the oceanic CO 2 system are lacking. We employ high-frequency CO 2 and optical observations covering the full seasonal cycle on the Scotian Shelf, Northwestern Atlantic Ocean, in order to unravel diel periodicity of the surface ocean carbon cycle and its effects on annual budgets. Significant diel periodicity occurs only if the water column is sufficiently stable as observed during seasonal warming. During that time biological CO 2 drawdown, or net community production (NCP), is delayed for several hours relative to the onset of photosynthetically available radiation (PAR), due to diel cycles in chlorophyll- a concentration and to grazing, both of which, we suggest, inhibit NCP in the early morning hours. In summer, NCP decreases by more than 90 %, coinciding with the seasonal minimum of the mixed layer depth and resulting in the disappearance of the diel CO 2 periodicity in the surface waters.

Beschreibung: A. Santi and A. Spiro The presentation of supergravity theories of our previous paper Super-Poincare algebras, space-times, and supergravities. I is re-formulated in the language of Berezin-Leites-Kostant theory of supermanifolds. It is also shown that the equations of Cremmer, Julia, and Scherk's theory of 11D-supergrav ... [J. Math. Phys. 53, 032505 (2012)] published Wed Mar 14, 2012.

Beschreibung: Tong Zhou and Zuo-nong Zhu In this paper, soliton interactions in three semidiscrete integrable systems are studied. It will be shown that in some cases the solitary waves of the semidiscrete integrable systems can interact elastically, i.e., the shapes, the amplitudes, and the velocities of waves preserve after undergoing co ... [J. Math. Phys. 53, 033507 (2012)] published Thu Mar 15, 2012.

Beschreibung: Gus Gutoski The present paper studies an operator norm that captures the distinguishability of quantum strategies in the same sense that the trace norm captures the distinguishability of quantum states or the diamond norm captures the distinguishability of quantum channels. Characterizations of its unit ball an ... [J. Math. Phys. 53, 032202 (2012)] published Wed Mar 14, 2012.

Beschreibung: Contribution of flowering trees to urban atmospheric biogenic volatile organic compound emissions Biogeosciences Discussions, 9, 3145-3172, 2012 Author(s): R. Baghi, D. Helmig, A. Guenther, T. Duhl, and R. Daly Emissions of biogenic volatile organic compounds (BVOC) from urban trees during and after blooming were measured during spring and early summer 2009 in Boulder, Colorado. Air samples were collected onto solid adsorbent cartridges from branch enclosures on the tree species crabapple, horse chestnut, honey locust, and hawthorn. These species constitute ~65 % of the insect-pollinated fraction of the flowering tree canopy (excluding catkin-producing trees) from the street area managed by the City of Boulder. Samples were analyzed for C 10 –C 15 BVOC by thermal desorption and gas chromatography coupled to a flame ionization detector and a mass spectrometer (GC/FID/MS). Identified emissions and emission rates from these four tree species during the flowering phase were found to vary over a wide range. Monoterpene emissions were identified for honey locust, horse chestnut and hawthorn. Sesquiterpene emissions were observed in horse chestnut and hawthorn samples. Crabapple flowers were found to emit significant amounts of benzyl alcohol and benzaldehyde. Floral BVOC emissions increased with temperature, generally exhibiting exponential temperature dependence. Changes in BVOC speciation during and after the flowering period were observed for every tree studied. Emission rates were significantly higher during the blooming compared to the vegetative state for crabapple and honey locust. Total normalized (30 °C) monoterpene emissions from honey locust were higher during flowering (5.26 μg Cg −1 h −1 ) than after flowering (1.23 μg Cg −1 h −1 ). The total normalized BVOC emission rate from crabapple (93 μg Cg −1 h −1 ) during the flowering period is of the same order as isoprene emissions from oak trees, which are among the highest BVOC emissions observed from plants to date. These findings illustrate that during the relatively brief springtime flowering period, floral emissions constitute by far the most significant contribution to the BVOC flux from these tree species, some of which are leafless at this time. Experimental results were integrated into the MEGAN biogenic emission model and simulations were performed to estimate the contribution of floral BVOC emissions to the total urban BVOC flux during the spring flowering period. The floral BVOC emitted during this three-month simulation are equivalent to 11 % of the cumulative monoterpene flux for the Boulder urban area.

Beschreibung: Li Ren, Qiang Mu, and Yongzheng Zhang The natural filtrations of hamiltonian superalgebras of formal vector fields are proved to be invariant under their automorphism group, by determining the set of ad-quasi-nilpotent elements. Thereby, the automorphism group of these Lie superalgebras are determined. ... [J. Math. Phys. 53, 033506 (2012)] published Thu Mar 15, 2012.

Beschreibung: Contributions of ectomycorrhizal fungal mats to forest soil respiration Biogeosciences Discussions, 9, 1635-1666, 2012 Author(s): C. L. Phillips, L. A. Kluber, J. P. Martin, B. A. Caldwell, and B. J. Bond Distinct aggregations of fungal hyphae and rhizomorphs, or "mats" formed by some genera of ectomycorrhizal (EcM) fungi are common features of soils in coniferous forests of the Pacific Northwest. We measured in situ respiration rates of Piloderma mats and neighboring non-mat soils in an old-growth Douglas-fir forest in Western Oregon to investigate whether there was an incremental increase in respiration from mat soils, and to estimate mat contributions to total soil respiration. We found that areas where Piloderma mats colonized the organic horizon often had higher soil surface flux than non-mats, with the incremental increase in respiration averaging 16 % across two growing seasons. Both soil physical factors and biochemistry were related to the higher surface flux of mat soils. When air-filled pore space was low (high soil moisture), soil CO 2 production was concentrated into near-surface soil horizons where mats tend to colonize, resulting in greater apparent differences in respiration between mat and non-mat soils. Respiration rates were also correlated with the activity of chitin-degrading soil enzymes. This suggests that the elevated activity of fungal mats may be related to consumption or turnover of chitinous fungal cell-wall materials. We found Piloderma mats present across 57 % of the soil surface in the study area, and use this value to estimate a respiratory contribution from mats at the stand-scale of about 9 % of total soil respiration. The activity of EcM mats, which includes both EcM fungi and microbial associates, was estimated to constitute a substantial portion of total soil respiration in this old-growth Douglas-fir forest.

Beschreibung: Wlodzimierz Natorf We generalize the result of Lukacs et al. on asymptotic stability of the Schwarzschild metric with respect to perturbations in the Robinson-Trautman class of metrics to the case of Petrov type II twisting metrics, under the condition of asymptotic flatness at future null infinity. The Bondi energy i ... [J. Math. Phys. 53, 022503 (2012)] published Tue Feb 7, 2012.

Beschreibung: Denis Borisov and Giuseppe Cardone We consider a planar waveguide with twisted boundary conditions. By twisting we mean a special combination of Dirichlet and Neumann boundary conditions. Assuming that the width of the waveguide goes to zero, we identify the effective (limiting) operator as the width of the waveguide tends to zero, e ... [J. Math. Phys. 53, 023503 (2012)] published Tue Feb 7, 2012.

Beschreibung: Chang-Guang Shi and Minoru Hirayama An application of the equation proposed by the present authors, which is equivalent to the static field equation of the Faddeev model, is discussed. Under some assumptions on the space and on the form of the solution, the field equation is reduced to a nonlinear ordinary differential equation of sec ... [J. Math. Phys. 53, 022301 (2012)] published Tue Feb 7, 2012.

Beschreibung: Kazuhide Matsuda We completely classify the rational solutions of the Noumi and Yamada system of type A, which is a generalization of the fourth Painleve equation. The rational solutions are classified to three by the Backlund transformation group. ... [J. Math. Phys. 53, 023504 (2012)] published Wed Feb 8, 2012.

Beschreibung: Remote sensing-based estimation of gross primary production in a subalpine grassland Biogeosciences Discussions, 9, 1711-1758, 2012 Author(s): M. Rossini, S. Cogliati, M. Meroni, M. Migliavacca, M. Galvagno, L. Busetto, E. Cremonese, T. Julitta, C. Siniscalco, U. Morra di Cella, and R. Colombo This study investigates the performances in a terrestrial ecosystem of gross primary production (GPP) estimation of a suite of spectral vegetation indexes (VIs) that can be computed from currently orbiting platforms. Vegetation indexes were computed from near-surface field spectroscopy measurements collected using an automatic system designed for high temporal frequency acquisition of spectral measurements in the visible near-infrared region. Spectral observations were collected for two consecutive years in Italy in a subalpine grassland equipped with an Eddy Covariance (EC) flux tower which provides continuous measurements of net ecosystem carbon dioxide (CO 2 ) exchange (NEE) and the derived GPP. Different VIs were calculated based on ESA-MERIS and NASA-MODIS spectral bands and correlated with biophysical (Leaf Area Index, LAI; fraction of photosynthetically active radiation intercepted by green vegetation, f IPAR g ), biochemical (chlorophyll concentration) and ecophysiological (green light-use efficiency, LUE g ) canopy variables. In this study, the normalized difference vegetation index (NDVI) showed better correlations with LAI and f PAR g ( r = 0.90 and 0.95, respectively), the MERIS terrestrial chlorophyll index (MTCI) with leaf chlorophyll content ( r = 0.91) and the Photochemical Reflectance Index (PRI 551 ), computed as ( R 531 − R 551 )/( R 531 + R 551 ) with LUE g ( r = 0.64). Subsequently, these VIs were used to estimate GPP using different modelling solutions based on the light-use efficiency model describing the GPP as driven by the photosynthetically active radiation absorbed by green vegetation (APAR g ) and by the efficiency (ε) with which plants use the absorbed radiation to fix carbon via photosynthesis. Results show that GPP can be successfully modelled with a combination of VIs and meteorological data or VIs only. Vegetation indexes designed to be more sensitive to chlorophyll content explained most of the variability in GPP in the ecosystem investigated, characterized by a strong seasonal dynamic of GPP. Accuracy in GPP estimation slightly improves when taking into account high frequency modulations of GPP driven by incident PAR or modelling LUE g with the PRI in model formulation. Similar results were obtained for both measured daily VIs and VIs obtained as 16-day composite time series and then downscaled from the compositing period to daily scale (resampled data). However, the use of resampled data rather than measured daily input data decreases the accuracy of the total GPP estimation on an annual basis.

Beschreibung: Soil organic carbon storage changes in coastal wetlands of the modern Yellow River Delta from 2000 to 2009 Biogeosciences Discussions, 9, 1759-1779, 2012 Author(s): J. Yu, Y. Wang, Y. Li, H. Dong, D. Zhou, G. Han, H. Wu, G. Wang, P. Mao, and Y. Gao Soil carbon sequestration plays an essential role in mitigating CO 2 increases and the subsequently global greenhouse effect. The storages and dynamics of soil organic carbon (SOC) of 0–30 cm soil depth in different landscape types including beaches, reservoir and pond, reed wetland, forest wetland, bush wetland, farmland, building land, bare land (severe saline land) and salt field in the modern Yellow River Delta (YRD), were studied based on the data of the regional survey and laboratory analysis. The landscape types were classified by the interpretation of remote sensing images of 2000 and 2009, which was calibrated by field survey results. The results revealed an increase of 10.59 km 2 in the modem YRD area from 2000 to 2009. The SOC density varied ranging from 0.73 kg m −2 to 21.60 kg m −2 at depth of 30 cm. There were ~3.97 × 10 6 t and 3.98 × 10 6 t SOC stored in the YRD in 2000 and 2009, respectively. The SOC storages changed greatly in beaches, bush wetland, farm land and salt field which were affected dominantly by anthropogenic activities. The area of the YRD increased greatly within 10 yr, however, the small increase of SOC storage in the region was observed due to landscape changes, indicating that the modern YRD was a potential carbon sink and anthropogenic activity was a key factor for SOC change.

Beschreibung: Tian Zhou Xu In this paper, we study the stability of the multi-Jensen mappings in non-Archimedean normed spaces. The results improve and extend some recent results. ... [J. Math. Phys. 53, 023507 (2012)] published Mon Feb 13, 2012.

Beschreibung: Stefano De Leo and Gisele Ducati In looking for quaternionic violations of quantum mechanics, we discuss the delay time for pure quaternionic potentials. Our study shows the energy region which amplifies the difference between quaternionic and complex quantum mechanics. ... [J. Math. Phys. 53, 022102 (2012)] published Mon Feb 13, 2012.

Beschreibung: Samuel Friot and David Greynat Multiple Mellin-Barnes integrals are often used for perturbative calculations in particle physics. In this context, the evaluation of such objects may be performed through residues calculations which lead to their expression as multiple power series and logarithms of the parameters involved in the p ... [J. Math. Phys. 53, 023508 (2012)] published Mon Feb 13, 2012.

Beschreibung: Implications of observed inconsistencies in carbonate chemistry measurements for ocean acidification studies Biogeosciences Discussions, 9, 1781-1792, 2012 Author(s): C. J. M. Hoppe, G. Langer, S. D. Rokitta, D. A. Wolf-Gladrow, and B. Rost The growing field of ocean acidification research is concerned with the investigation of organisms' responses to increasing p CO 2 values. One important approach in this context is culture work using seawater with adjusted CO 2 levels. As aqueous p CO 2 is difficult to measure directly in small scale experiments, it is generally calculated from two other measured parameters of the carbonate system (often A T , C T or pH). Unfortunately, the overall uncertainties of measured and subsequently calculated values are often unknown. Especially under high p CO 2 , this can become a severe problem with respect to the interpretation of physiological and ecological data. In the few datasets from ocean acidification research where all three of these parameters were measured, p CO 2 values calculated from A T and C T are typically about 30 % lower (i.e. ~300 μatm at a target p CO 2 of 1000 μatm) than those calculated from A T and pH or C T and pH. This study presents and discusses these discrepancies as well as likely consequences for the ocean acidification community. Until this problem is solved, one has to consider that calculated parameters of the carbonate system (e.g. p CO 2 , calcite saturation state) may not be comparable between studies, and that this may have important implications for the interpretation of CO 2 perturbation experiments.

Beschreibung: H. Hassanabadi, E. Maghsoodi, S. Zarrinkamar, and H. Rahimov Approximate analytical solutions of spin and pseudospin symmetry limits of Dirac equation are reported for the generalized Poschl-Teller scalar and vector potentials and a Coulomb tensor interaction by Nikiforov-Uvarov method. On the contrary to the cumbersome numerical procedures, the analytical ap ... [J. Math. Phys. 53, 022104 (2012)] published Wed Feb 15, 2012.

Beschreibung: Tamaghna Hazra, V. K. Chandrasekar, R. Gladwin Pradeep, and M. Lakshmanan General solutions of nonlinear ordinary differential equations (ODEs) are in general difficult to find; although, powerful integrability techniques exist in the literature for this purpose. It has been shown that in some scalar cases particular solutions may be found with little effort if it is poss ... [J. Math. Phys. 53, 023511 (2012)] published Wed Feb 15, 2012.

Beschreibung: Aurel Bejancu We study curvature problems on a nearly Riemannian manifold, which is a sub-Riemannian manifold (M, HM, g, VM) whose adapted tensor field given by (2.2) vanishes identically. First, we prove the existence and uniqueness of what we call horizontal Riemannian connection, which is a torsion-free and me ... [J. Math. Phys. 53, 023513 (2012)] published Fri Feb 17, 2012.

Beschreibung: Riverine influence on the tropical Atlantic Ocean biogeochemistry Biogeosciences Discussions, 9, 1945-1969, 2012 Author(s): L. Cotrim da Cunha and E. T. Buitenhuis We assess the role of riverine inputs of N, Si, Fe, organic and inorganic C in the tropical Atlantic Ocean using a global ocean biogeochemistry model. We use two sensitivity tests to investigate the role of the western (South American Rivers) and eastern (African Rivers) riverine nutrient inputs on the tropical Atlantic Ocean biogeochemistry (between 20° S–20° N and 70° W–20°). Increased nutrient availability from river inputs in this area (compared to an extreme scenario with no river nutrients) leads to an increase in 14 % (0.7 Pg C a −1 ) in open ocean primary production (PP), and 21 % (0.2 Pg C a −1 ) in coastal ocean PP. We estimate very modest increases in open and coastal ocean export production and sea-air CO 2 fluxes. Results suggest that in the tropical Atlantic Ocean, the large riverine nutrient inputs on the western side have a larger impact on primary production and sea-air CO 2 exchanges. On the other hand, African river inputs, although smaller than South American inputs, have larger impact on the coastal and open tropical Atlantic Ocean export production. This is probably due to a combination of nutrient trapping in upwelling areas off the Congo River outflow, and differences in delivered nutrient ratios leading to alleviation in limitation conditions mainly for diatoms.

Beschreibung: A. Elci The jet space of the Schrodinger equation and Noether's theorem are used to determine a set of particle trajectories that belong exclusively to an eigenfunction. These trajectories depend on a vector field [script A]-vector which satisfies two partial differential equations. Characteristic trajector ... [J. Math. Phys. 53, 122107 (2012)] published Tue Dec 18, 2012.

Beschreibung: Coral Patch seamount (NE Atlantic) – a sedimentological and macrofaunal reconnaissance based on video and hydroacoustic surveys Biogeosciences Discussions, 9, 18707-18753, 2012 Author(s): C. Wienberg, P. Wintersteller, L. Beuck, and D. Hebbeln The present study provides new knowledge about the so far largely unexplored Coral Patch seamount which is located in the NE Atlantic Ocean half-way between the Iberian Peninsula and Madeira. For the first time a detailed hydroacoustic mapping (MBES) in conjunction with video surveys (ROV, camera sled) were performed to describe the sedimentological and biological characteristics of this sub-elliptical ENE-WSW elongated seamount. Video observations were restricted to the south-western summit area of Coral Patch seamount (area: ~ 8 km 2 , water depth: 560–760 m) and revealed that this part of the summit is dominated by exposed hard substrate, whereas soft sediment is just a minor substrate component. Although exposed hardgrounds are dominant for this summit area, and thus, offer suitable habitat for settlement by benthic organisms, the macrofauna shows rather low abundance and diversity. In particular, scleractinian framework-building cold-water corals are apparently rare with very few isolated and small-sized live occurrences of the species Lophelia pertusa and Madrepora oculata . In contrast, dead coral framework and coral rubble are more frequent pointing to a higher abundance of cold-water corals on Coral Patch during the recent past. This is even supported by the observation of fishing lines that got entangled with rather fresh-looking coral frameworks. Overall, long lines and various species of commercially important fish were frequently observed emphasising the potential of Coral Patch as an important target for fisheries that may have impacted the entire benthic community. Hydroacoustic seabed classification covered the entire summit of Coral Patch and its northern and southern flanks (area: 560 km 2 ; water depth: 560–2660 m) and revealed extended areas dominated by mixed and soft sediments at the northern flank and to a minor degree at its easternmost summit and southern flank. Nevertheless, also these data predict most of the summit area to be dominated by exposed bedrock which would offer suitable habitat for benthic organisms. By comparing the locally restricted video observations and the broad-scale monitoring of a much larger and deeper seafloor area as derived by hydroacoustic seabed classification, it becomes obvious that habitat information obtained by in situ sampling may provide a rather scattered pattern about the entire seamount ecosystem. Solely with a combination of both methods, a satisfactory approach to describe the diverse characteristics of a seamount ecosystem can be derived which is in turn indispensable for future scientific monitoring campaigns as well as management and conservation purposes.

Beschreibung: High-resolution measurements of atmospheric molecular hydrogen and its isotopic composition at the West African coast of Mauritania Biogeosciences Discussions, 9, 18799-18829, 2012 Author(s): S. Walter, A. Kock, and T. Röckmann Oceans are a net source of molecular hydrogen (N 2 ) to the atmosphere, where nitrogen (N 2 ) fixation is assumed to be the main biological production pathway besides photochemical production from organic material. The sources can be distinguished using isotope measurements because of clearly differing isotopic signatures of the produced hydrogen. Here we present the first ship-borne measurements of atmospheric molecular H 2 mixing ratio and isotopic composition at the West African coast of Mauritania (16–25° W, 17–24° N). This area is one of the biologically most active regions of the world's oceans with seasonal upwelling events and characterized by strongly differing hydrographical/biological properties and phytoplankton community structures. The aim of this study was to identify areas of H 2 production and distinguish H 2 sources by isotopic signatures of atmospheric H 2 . Besides this a diurnal cycle of atmospheric H 2 was investigated. For this more than 100 air samples were taken during two cruises in February 2007 and 2008, respectively. During both cruises a transect from the Cape Verde Island towards the Mauritanian Coast was sampled. In 2007 additionally four days were sampled with a high resolution of one sample per hour. Our results clearly indicate the influence of local sources and suggest the Banc d'Arguin as a pool for precursors for photochemical H 2 production, whereas N 2 fixation could not be identified as a H 2 source during these two cruises. With our experimental setup we could demonstrate that variability in diurnal cycles is probably influenced and biased by released precursors for photochemical H 2 production and the origin of air masses. This means for further investigations that just measuring the mixing ratio of H 2 is insufficient to explain the variability of a diurnal cycle and support is needed, e.g. by isotopic measurements. However, measurements of H 2 mixing ratios, which are easy to conduct online during ship cruises could be a helpful tool to easily identify production areas of biological precursors such as VOC's for further investigations.

Beschreibung: Physical transport properties of marine microplastic pollution Biogeosciences Discussions, 9, 18755-18798, 2012 Author(s): A. Ballent, A. Purser, P. de Jesus Mendes, S. Pando, and L. Thomsen Given the complexity of quantitative collection, knowledge of the distribution of microplastic pollution in many regions of the world ocean is patchy, both spatially and temporally, especially for the subsurface environment. However, with knowledge of typical hydrodynamic behavior of waste plastic material, models predicting the dispersal of pelagic and benthic plastics from land sources into the ocean are possible. Here we investigate three aspects of plastic distribution and transport in European waters. Firstly, we assess patterns in the distribution of plastics found in fluvial strandlines of the North Sea and how distribution may be related to flow velocities and distance from source. Second, we model transport of non-buoyant preproduction pellets in the Nazaré Canyon of Portugal using the MOHID system after assessing the density, settling velocity, critical and depositional shear stress characteristics of such waste plastics. Thirdly, we investigate the effect of surface turbulences and high pressures on a range of marine plastic debris categories (various densities, degradation states and shapes tested) in an experimental water column simulator tank and pressure laboratory. Plastics deposited on North Sea strandlines varied greatly spatially, as a function of material composition and distance from source. Model outputs indicated that such dense production pellets are likely transported up and down canyon as a function of tidal forces, with only very minor net down canyon movement. Behaviour of plastic fragments under turbulence varied greatly, with the dimensions of the material, as well as density, playing major determining roles. Pressure was shown to affect hydrodynamic behaviours of only low density foam plastics at pressures ≥ 60 bar.

Beschreibung: Jan Hamhalter In the algebraic approach to quantum theory, a quantum observable is given by an element of a Jordan algebra and a state of the system is modelled by a normalized positive functional on the underlying algebra. Maximal deviation of a quantum observable is the largest statistical deviation one can obt ... [J. Math. Phys. 53, 122208 (2012)] published Wed Dec 19, 2012.

Beschreibung: Hellmut Baumgartel The paper presents a classification of the basic types of admissible solutions of the general Friedmann equation with non-vanishing cosmological constant and for the case that radiation and matter do not couple. There are four distinct types. The classification uses first the discriminant of a polyn ... [J. Math. Phys. 53, 122505 (2012)] published Wed Dec 19, 2012.

Beschreibung: Stefan Hollands and Karl-Henning Rehren Abstract not available. [J. Math. Phys. 53, 120401 (2012)] published Wed Dec 19, 2012.

Beschreibung: Yury G. Smirnov and Dmitry V. Valovik Coupled polarized electromagnetic wave propagation in a nonlinear dielectric layer filled with lossless, nonmagnetic, and isotropic medium is considered. The layer is located between two half-spaces with constant permittivities. The permittivity in the layer is described by Kerr law. Considered coup ... [J. Math. Phys. 53, 123530 (2012)] published Wed Dec 19, 2012.

Beschreibung: Effects of precipitation on soil respiration and its temperature/moisture sensitivity in three subtropical forests in Southern China Biogeosciences Discussions, 9, 15667-15698, 2012 Author(s): H. Jiang, Q. Deng, G. Zhou, D. Hui, D. Zhang, S. Liu, G. Chu, and J. Li Both long-term observation data and model simulations suggest an increasing chance of serious drought in the dry season and extreme flood in the wet season in Southern China, yet little is known about how changes in precipitation pattern will affect soil respiration in the region. We conducted a field experiment to study the responses of soil respiration to precipitation manipulations – precipitation exclusion to mimic drought, double precipitation to simulate flood, and ambient precipitation (Abbr. EP, DP and AP, respectively) – in three subtropical forests in Southern China. The three forests include Masson pine forest (PF), coniferous and broadleaved mixed forest (MF) and monsoon evergreen broadleaved forest (BF). Our observations showed that altered precipitation can strongly influence soil respiration, not only through the well-known direct effects of soil moisture, but also by modification on both moisture and temperature sensitivity of soil respiration. In the dry season, soil respiration and its temperature sensitivity in the three forests showed rising trends with precipitation increase, and its moisture sensitivity showed an opposite trend. In the wet season, the EP treatment also decreased soil respiration and its temperature sensitivity, and enhanced moisture sensitivity in all three forests. Soil respiration under the DP treatment increased significantly in the PF only, and no significant change was found for either moisture or temperature sensitivity. However, the DP treatment in the MF and BF reduced temperature sensitivity significantly. Our results indicated that soil respiration would decrease in the three subtropical forests if soil moisture continues to decrease in the future. More rainfall in the wet season could have limited effect on the response of soil respiration to the rising of temperature in the BF and MF.

Beschreibung: J.-B. Bru and W. de Siqueira Pedra We study the thermodynamic properties of a certain type of space-inhomogeneous Fermi and quantum spin systems on lattices. We are particularly interested in the case where the space scale of the inhomogeneities stays macroscopic, but very small as compared to the side-length of the box containing fe ... [J. Math. Phys. 53, 123301 (2012)] published Thu Nov 8, 2012.

Beschreibung: M. Vatandoost and Y. Bahrampour A space-time may be regarded as a partially ordered set by causal relations. Recently, as a poset, a sphere order representation of a space-time is considered and some interesting results are obtained. In this paper, we define a weakly causally convex open set and characterize connected open subsets ... [J. Math. Phys. 53, 122501 (2012)] published Thu Nov 8, 2012.

Beschreibung: Alexandru Chirvasitu We show that the quotients of Wang and Van Daele's universal quantum groups by their centers are simple in the sense that they have no normal quantum subgroups, thus providing the first examples of simple compact quantum groups with non-commutative fusion rings. ... [J. Math. Phys. 53, 123509 (2012)] published Tue Nov 13, 2012.

Beschreibung: Andro Mikelic and Mary F. Wheeler We undertake establishing well-posedness of the dynamic Biot-Allard equations. It is obtained using the precise properties of the dynamic permeability matrix following the homogenization derivation of the model. By taking the singular limit of the contrast coefficient, the quasi-static Biot system c ... [J. Math. Phys. 53, 123702 (2012)] published Tue Nov 13, 2012.

Beschreibung: Fabio Bagarello, Atsushi Inoue, and Camillo Trapani We continue our analysis of the consequences of the commutation relation [S,T]=[openface 1], where S and T are two closable unbounded operators. The weak sense of this commutator is given in terms of the inner product of the Hilbert space [script H], where the operators act. We also consider what we ... [J. Math. Phys. 53, 123510 (2012)] published Tue Nov 13, 2012.

Beschreibung: Ricardo Gallego Torrome, Paolo Piccione, and Henrique Vitorio In this work, a version of Fermat's principle for causal curves with the same energy in time orientable Finsler spacetimes is proved. We calculate the second variation of the time arrival functional along a geodesic in terms of the index form associated with the Finsler spacetime Lagrangian. Then th ... [J. Math. Phys. 53, 123511 (2012)] published Tue Nov 13, 2012.

Beschreibung: Tamar Friedmann and C. R. Hagen The spectrum of the square of the angular momentum in arbitrary dimensions is derived using only group theoretical techniques. This is accomplished by application of the Lie algebra of the noncompact group O(2, 1). ... [J. Math. Phys. 53, 122102 (2012)] published Tue Nov 13, 2012.

Beschreibung: Revisiting factors controlling methane emissions from high-arctic tundra Biogeosciences Discussions, 9, 15853-15900, 2012 Author(s): M. Mastepanov, C. Sigsgaard, T. Tagesson, L. Ström, M. P. Tamstorf, M. Lund, and T. R. Christensen Among the numerous studies of methane emission from northern wetlands the number of measurements carried on at high latitudes (north of the Arctic Circle) is very limited, and within these there is a bias towards studies of the growing season. Here we present results of five years of automatic chamber measurements at a high-arctic location in Zackenberg, NE Greenland covering both the growing seasons and two months of the following freeze-in period. The measurements show clear seasonal dynamics in methane emission. The start of the growing season increase in CH 4 fluxes were strongly related to the date of snow melt. The greatest variation in fluxes between the study years were observed during the first part of the growing season. Somewhat surprisingly this variability could not be explained by commonly known factors controlling methane emission, i.e. temperature and water table position. Late in the growing season CH 4 emissions were found to be very similar between the study years (except the extremely dry 2010) despite large differences in climatic factors (temperature and water table). Late-season bursts of CH 4 coinciding with soil freezing in the autumn were observed at least during three years between 2006 and 2010. The accumulated emission during the freeze-in CH 4 bursts was comparable in size with the growing season emission for the year 2007, and about one third of the growing season emissions for the years 2009 and 2010. In all three cases the CH 4 burst was accompanied by a~corresponding episodic increase in CO 2 emission, which can compose a significant contribution to the annual CO 2 flux budget. The most probable mechanism of the late season CH 4 and CO 2 bursts is physical release of gases, accumulated in the soil during the growing season. In this study we investigate the drivers and links between growing season and late season fluxes. The reported surprising seasonal dynamics of CH 4 emissions at this site show that there are important occasions where conventional knowledge on factors controlling methane emissions is overruled by other processes, acting in longer than seasonal time scales. Our findings suggest the importance of multiyear studies with continued focus on shoulder seasons.

Beschreibung: Distribution of methane in the Lena Delta and Buor Khaya Bay, Russia Biogeosciences Discussions, 9, 16213-16237, 2012 Author(s): I. Bussmann The Lena River is one of the largest Russian rivers draining into the Laptev Sea. The permafrost areas surrounding the Lena are predicted to melt at increasing rates due to global temperature increases. With this melting, large amounts of carbon – either organic or as methane – will reach the waters of the Lena and the adjacent Buor Khaya Bay (Laptev Sea). Methane concentrations and the isotopic signal of methane in the waters of the Lena Delta and estuary were monitored from 2008 to 2010. Meltwater run-off of permafrost soils produced hotspots for methane input into the river system (median concentration 1500 nM) compared with concentrations of around 100 nM observed in the main channels of the Lena. Within the river, especially at sites with meltwater input, microbiological experiments indicated strong in situ methane production but a very low methane oxidation potential. In the estuary of Buor Khaya Bay, methane concentrations decreased towards background levels of 20 nM. Here, the strong stratification of the water column permits the dilution of methane with seawater, and methane is released mainly by diffusion into the atmosphere.

Beschreibung: Spectrally resolved efficiencies of carbon monoxide (CO) photoproduction in the Western Canadian Arctic: particles versus solutes Biogeosciences Discussions, 9, 16161-16211, 2012 Author(s): G. Song, H. Xie, S. Bélanger, and M. Babin Spectrally resolved efficiency (i.e. apparent quantum yield, AQY) of carbon monoxide (CO) photoproduction is a useful indicator of substrate photoreactivity and a crucial parameter for modeling CO photoproduction rates in the water column. Recent evidence has suggested that CO photoproduction from particles in marine waters is significant compared to the well-known CO production from chromophoric dissolved organic matter (CDOM) photodegradation. Although CDOM-based CO AQY spectra have been extensively determined, little is known of this information on the particulate phase. Using water samples collected from the Mackenzie estuary, shelf, and Canada Basin in the Southeastern Beaufort Sea, the present study for the first time quantified the AQY spectra of particle-based CO photoproduction and compared them with the concomitantly determined CDOM-based CO AQY spectra. CO AQYs of both particles and CDOM decreased with wavelength but the spectral shape of the particulate AQY was flatter in the visible regime. This feature resulted in a disproportionally higher visible light-driven CO production by particles, thereby increasing the ratio of particle- to CDOM-based CO photoproduction with depth in the euphotic zone. In terms of depth-integrated production in the euphotic zone, CO formation from CDOM was dominated by the ultraviolet (UV, 290–400 nm) radiation whereas UV and visible light played roughly equal roles in CO production from particles. Spatially, CO AQY of bulk particulate matter (i.e. the sum of organics and inorganics) augmented from the estuary to shelf to basin while CO AQY of CDOM trended inversely. Water from the deep chlorophyll maximum layer revealed higher CO AQYs than did surface water for both particles and CDOM. CO AQY of bulk particulate matter exceeded that of CDOM on the shelf and in the basin but the sequence reversed in the estuary. Mineral absorption-corrected CO AQY of particulate organic matter (POM) was, however, greater than its CDOM counterpart in all three sub-regions and displayed magnitudes in the estuary that were no inferior to those in shelf and offshore waters. In terms of CO photoproduction, POM was thus more photoreactive than CDOM, irrespective of the organic matter's origins (i.e. terrigenous or marine). Riverine CDOM exhibited higher photoreactivity than marine CDOM and land-derived POM appeared similarly or more photoreactive than marine POM. AQY-based modeling indicates that CO photoproduction in the study area is underestimated by 13–48 % if the particulate term is ignored.

Beschreibung: Radium-based estimates of cesium isotope transport and total direct ocean discharges from the Fukushima Nuclear Power Plant accident Biogeosciences Discussions, 9, 16139-16160, 2012 Author(s): M. A. Charette, C. F. Breier, P. B. Henderson, S. M. Pike, I. I. Rypina, S. R. Jayne, and K. O. Buesseler Radium has four naturally occurring isotopes that have proven useful in constraining water mass source, age, and mixing rates in the coastal and open ocean. In this study, we used radium isotopes to determine the fate and flux of runoff-derived cesium from the Fukushima Nuclear Power Plant (NPP). During a June 2011 cruise, the highest Cs concentrations were found along the eastern shelf of northern Japan, from Fukushima south, to the edge of the Kuroshio current, and in an eddy ∼ 130 km from the NPP site. Locations with the highest cesium also had some of the highest radium activities, suggesting much of the direct ocean discharges of Cs remained in the coastal zone 2–3 months after the accident. We used a short-lived Ra isotope ( 223 Ra, t 1/2 = 11.4 d) to derive an average water mass age ( T r ) in the coastal zone of 32 days. To ground-truth the Ra age model, we conducted a direct, station-by-station comparison of water mass ages with a numerical oceanographic model and found them to be in excellent agreement (model avg. T r = 27 days). From these independent T r values and the inventory of Cs within the water column at the time of our cruise, we were able to calculate an offshore 134 Cs flux of 3.9–4.6 × 10 13 Bq d −1 . Radium-228 ( t 1/2 = 5.75 yr) was used to derive a vertical eddy diffusivity ( K z ) of 0.7 m 2 d −1 (0.1 cm 2 s −1 ); from this K z and 134 Cs inventory, we estimated a 134 Cs flux across the pycnocline of 1.8 × 10 4 Bq d −1 for the same time period. On average, our results show that horizontal mixing loss of Cs from the coastal zone was ∼ 10 9 greater than vertical exchange below the surface mixed layer. Finally, a mixing/dilution model that utilized our Ra-based and oceanographic model water mass ages produced a direct ocean discharge of 134 Cs from the FNPP of 11–16 PBq at the time of the peak release in early April 2011. Our results can be used to calculate discharge of other water-soluble radionuclides that were released to the ocean directly from the Fukushima NPP.

Beschreibung: Soil respiration compartments on an aging managed heathland: can model selection procedures contribute to our understanding of ecosystem processes? Biogeosciences Discussions, 9, 16239-16301, 2012 Author(s): G. R. Kopittke, E. E. van Loon, A. Tietema, and D. Asscheman Soil respiration studies are increasingly undertaken with the aim of quantifying C fluxes and predicting changes for the future. The interpretation of field data into annual C loss predictions requires the use of modeling tools which generally include model variables related to the underlying drivers of soil respiration, such as soil temperature, soil moisture and plant activity. Very few studies have reported using model selection procedures in which structurally different models are calibrated, then validated on separate observation datasets and the outcomes critically compared. This study utilized thorough model selection procedures to determine soil heterotrophic (microbial) and autotrophic (root) respiration for a heathland chronosequence. The model validation process identified that none of the six measured plant variables explained any data variation when included in models with soil temperature, which contradicts many current studies. The best predictive model used a generalized linear mixed effect model format with soil temperature as the only variable. There were no heterotrophic respiration differences between the community ages. In contrast, autotrophic respiration was significantly greater on the youngest vegetation (55 % of total soil respiration in summer) and decreased as the plants aged (oldest vegetation: 37 % of total soil respiration in summer). Total annual soil C loss from the youngest and oldest communities was estimated to be 650 and 435 g C m −2 yr −1 respectively. Heathlands are cultural landscapes which are managed through cyclical cutting, burning or grazing practices. Understanding the C fluxes from these ecosystems provides information on the optimal management cycle-time to maximize C uptake and minimize C output. Inclusion of the predicted soil fluxes into a preliminary ecosystem C balance suggested that the youngest vegetation is a C sink while the oldest vegetation is a C source, indicating that shorter management cycles could reduce C emissions.

Beschreibung: Biological production in the Bellingshausen Sea from oxygen-to-argon ratios and oxygen triple isotopes Biogeosciences Discussions, 9, 16033-16085, 2012 Author(s): K. Castro-Morales, N. Cassar, and J. Kaiser We present estimates of mixed layer net community oxygen production ( N ) and gross oxygen production ( G ) of the Bellingshausen Sea in March and April 2007. N was derived from oxygen-to-argon (O 2 / Ar) ratios; G was derived using the dual-delta method from triple oxygen isotope measurements. In addition, O 2 profiles were collected at 253 CTD stations. N is often approximated by the biological oxygen air-sea exchange flux ( F bio ) based on the O 2 / Ar supersaturation, assuming that significant horizontal or vertical fluxes are absent. Here, we show that the effect of vertical fluxes alone can account for F bio values 〈 0 in large parts of the Bellingshausen Sea towards the end of the productive season, which could be mistaken to represent net heterotrophy. Thus, improved estimates of mixed-layer N can be derived from the sum of F bio , F e (entrainment from the upper thermocline during mixed-layer deepening) and F v (diapycnal eddy diffusion across the base of the mixed layer). In the Winter Sea Ice Zone (WSIZ), the corresponding correction results in a small change of F bio = (30 ± 17) mmol m −2 d −1 to N = (34 ± 17) mmol m −2 d −1 . However, in the permanent open ocean zone (POOZ), the original F bio value of (−17 ± 10) mmol m −2 d −1 gives a corrected value for N of (−2 ± 18) mmol m −2 d −1 . We hypothesize that in the WSIZ enhanced water column stability due to the release of freshwater and nutrients from sea-ice melt may account for the higher N-value. These results stress the importance of accounting for physical biases when estimating mixed layer-marine productivity from in situ O 2 / Ar ratios.

Beschreibung: Constraints from atmospheric CO 2 and satellite-based vegetation activity observations on current land carbon cycle trends Biogeosciences Discussions, 9, 16087-16138, 2012 Author(s): D. Dalmonech and S. Zaehle Terrestrial ecosystem models used for Earth system modelling show a significant divergence in future patterns of ecosystem processes, in particular carbon exchanges, despite a seemingly common behaviour for the contemporary period. An in-depth evaluation of these models is hence of high importance to achieve a better understanding of the reasons for this disagreement. Here, we develop an extension for existing benchmarking systems by making use of the complementary information contained in the observational records of atmospheric CO 2 and remotely-sensed vegetation activity to provide a firm set of diagnostics of ecosystem responses to climate variability in the last 30 yr at different temporal and spatial scales. The selection of observational characteristics (traits) specifically considers the robustness of information given the uncertainties in both data and evaluation analysis. In addition, we provide a baseline benchmark, a minimum test that the model under consideration has to pass, to provide a more objective, quantitative evaluation framework. The benchmarking strategy can be used for any land surface model, either driven by observed meteorology or coupled to a climate model. We apply this framework to evaluate the offline version of the MPI-Earth system model's land surface scheme JSBACH. We demonstrate that the complementary use of atmospheric CO 2 and satellite based vegetation activity data allows to pinpoint specific model failures that would not be possible by the sole use of atmospheric CO 2 observations.

Beschreibung: Seasonal and spatial comparisons of phytoplankton growth and mortality rates due to microzooplankton grazing in the northern South China Sea Biogeosciences Discussions, 9, 16005-16032, 2012 Author(s): B. Chen, L. Zheng, B. Huang, S. Song, and H. Liu We conducted a comprehensive investigation on the microzooplankton herbivory effect on phytoplankton in the northern South China Sea (SCS) using the seawater dilution technique at surface and deep chlorophyll maximum (DCM) layers in two cruises (July–August of 2009 and January of 2010). We compared vertical (surface vs. DCM), spatial (onshore vs. offshore), and seasonal (summer vs. winter) differences of phytoplankton growth (μ 0 ) and microzooplankton grazing rates ( m ). During summer, both μ 0 and m were significantly higher at the surface than at the layer of DCM, which was below the mixed layer. During winter, surface μ 0 was significantly higher than at DCM, while m was not significantly different between the two layers, both of which were contained within the mixed layer. Surface μ 0 was, on average, significantly higher in summer than in winter; while average surface m was not different between the two seasons. There were no significant cross-shelf trends of μ 0 in summer or winter surface waters. In surface waters, μ 0 was not correlated with ambient nitrate concentrations and the effect of nutrient enrichment on phytoplankton growth was not pronounced. There was a decreasing trend of m from shelf to basin surface waters in summer, but not in winter. Microzooplankton grazing effect on phytoplankton ( m /μ 0 ) did not increase with distance offshore, suggesting that the importance of microzooplankton as grazers of phytoplankton may not decrease in onshore waters. On average, microzooplankton grazed 73% and 65% of the daily primary production in summer and winter, respectively.

Beschreibung: Interconnectivity vs. isolation of prokaryotic communities in European deep-sea mud volcanoes Biogeosciences Discussions, 9, 17377-17400, 2012 Author(s): M. G. Pachiadaki and K. A. Kormas By exploiting the available data on 16S rRNA gene sequences – spanning over a sampling period of more than 10 yr – retrieved from sediments of the Haakon Mosby mud volcano (HMMV), Gulf of Cadiz (GoC) and eastern Mediterranean (Amsterdam and Kazan mud volcanoes; AMSMV, KZNMV) mud volcanoes/pockmarks, we investigated whether these systems are characterized by high (interconnectivity) or low (isolation) connection degree based on shared bacterial and archaeal phylotypes. We found only two archaeal and two bacterial phylotypes to occur in all three sites and a few more that were found in two of the three sites. Although the number of shared species depends a lot on the analysis depth of each sample, the majority of the common phylotypes were related mostly to cold seep deep-sea habitats, while for some of them their relative abundance was high enough to be considered as key-species for the habitat they were found. As new tools, like next generation sequencing platforms, are more appropriate for revealing greater depth of diversity but also allow sample replication and uniform sampling protocols, and gain wider recognition and usage, future attempts are more realistic now for fully elucidating the degree of specificity in deep-sea mud volcanoes and pockmarks microbial communities.

Beschreibung: Density and distribution of megafauna at the Håkon Mosby Mud Volcano (the Barents Sea) based on image analysis Biogeosciences Discussions, 9, 17475-17517, 2012 Author(s): E. Rybakova (Goroslavskaya), S. Galkin, M. Bergmann, T. Soltwedel, and A. Gebruk During a survey of the Håkon Mosby Mud Volcano (HMMV), located on the Bear Island Fan in the southwest Barents Sea at ~ 1250 m water depth, different habitats inside the volcano caldera and outside it were photographed using a towed camera platform, an Ocean Floor Observation System (OFOS). Three transects were performed across the caldera and one outside, in the background area, each transect was ~ 2 km in length. We compared the density, taxa richness and diversity of non-symbiotrophic megafauna in areas inside the volcano caldera with different bacterial mat and pogonophoran tubeworm cover. Significant variations in megafaunal composition, density and distribution were found between considered areas. Total megafaunal density was highest in areas of dense pogonophoran populations (mean 52.9 ind. m −2 ) followed by areas of plain light-coloured sediment that were devoid of bacterial mats and tubeworms (mean 37.7 ind. m −2 ). The lowest densities were recorded in areas of dense bacterial mats (mean ≤ 1.4 ind. m −2 ). Five taxa contributed to most of the observed variation: the ophiuroid Ophiocten gracilis , lysianassid amphipods, the pycnogonid Nymphon macronix , the caprellid Metacaprella horrida and the fish Lycodes squamiventer . In agreement with previous studies, three zones within the HMMV caldera were distinguished, based on different habitats and megafaunal composition: "bacterial mats", "pogonophoran fields" and "plain light-coloured sediments". The zones were arranged almost concentrically around the central part of the caldera that was devoid of visible megafauna. The total number of taxa showed little variation inside (24 spp.) and outside the caldera (26 spp.). The density, diversity and composition of megafauna varied substantially between plain light-coloured sediment areas inside the caldera and the HMMV background. Megafaunal density was lower in the background (mean 25.3 ind. m −2 ) compared to areas of plain light-coloured sediments inside the caldera.

Beschreibung: Phosphorus sorption and buffering mechanisms in suspended sediments from the Yangtze Estuary and Hangzhou Bay, China Biogeosciences Discussions, 9, 17519-17538, 2012 Author(s): M. Li, M. J. Whelan, G. Wang, and S. M. White The adsorption isotherm and the mechanism of the buffering effect are important controls on phosphorus behaviors in estuaries and are important for estimating phosphate concentrations in aquatic environments. In this paper, we derive phosphate adsorption isotherms in order to investigate sediment adsorption and buffering capacity for phosphorus discharged from sewage outfalls in the Yangtze Estuary and Hangzhou Bay near Shanghai, China. Experiments were also carried out at different temperatures in order to explore the buffering effects for phosphate. The results show that P sorption in sediments with low fine particle fractions was best described using exponential equations. Some P interactions between water and sediment may be caused by the precipitation of CaHPO 4 from Ca 2+ and HPO 4 2− when the phosphate concentration in the liquid phase is high. Results from the buffering experiments suggest that the Zero Equilibrium Phosphate Concentrations (EPC 0 ) vary from 0.014 mg l −1 to 0.061 mg l −1 , which are consistent with measured phosphate concentrations in water samples collected at the same time as sediment sampling. Values of EPC 0 and linear sorption coefficients ( K ) in sediments with high fine particle and organic matter contents are relatively high, which implies that they have high buffering capacity. Both EPC 0 and K increase with increasing temperature, indicating a higher P buffering capacity at high temperatures.

Beschreibung: Seasonal, daily and diel N 2 effluxes in permeable carbonate sediments Biogeosciences Discussions, 9, 17437-17473, 2012 Author(s): B. D. Eyre, I. R. Santos, and D. T. Maher Benthic metabolism and inorganic nitrogen and N 2 flux rates (denitrification) were measured in permeable carbonate sands from Heron Island (Great Barrier Reef). Some of the N 2 flux rates were among the highest measured in sediments. All benthic fluxes showed a significant difference between seasons with higher rates in summer and late summer. There was no distinct response of the benthic system to mass coral spawning. Instead, changes in benthic fluxes over 12 days in summer appears to be driven by tidal changes in water depth and associated changes in phytosynthetically active radiation reaching the sediments. Dark N 2 fluxes were strongly correlated to benthic oxygen consumption across all sites and seasons ( r 2 = 0.64; p 〈 0.005; slope = 0.036). However, there were seasonal differences with a steeper slope in summer than winter reflecting either more efficient coupling between respiration and nitrification-denitrification at higher temperatures or different sources of organic matter. Adding data from published studies on carbonate sands revealed two slopes in the dark N 2 flux versus benthic oxygen consumption relationship. The lower slope (0.035) was most likely due to high carbon : nitrogen (C : N) organic matter from coral reefs, but competition by benthic microalgae for nitrogen, N-fixation or inefficient coupling between respiration and nitrification-denitrification can not be excluded. The steeper slope (0.089) was most likely due to respiration being driven by low C : N phyto-detritus. If the different slopes were driven by the sources of organic matter then global estimates of continental shelf denitrification are probably about right. In contrast, global estimates of continental shelf may be over-estimated if the low slope was due to inefficient coupling between respiration and nitrification-denitrification and also due to reduced N 2 effluxes in the light associated with competition by benthic microalgae for nitrogen and N-fixation.

Beschreibung: Spatial variability of particle-attached and free-living bacterial diversity in surface waters from the Mackenzie River to the Beaufort Sea (Canadian Arctic) Biogeosciences Discussions, 9, 17401-17435, 2012 Author(s): E. Ortega-Retuerta, F. Joux, W. H. Jeffrey, and J.-F. Ghiglione We explored the patterns of total and active bacterial community structure in a gradient covering surface waters from the Mackenzie River to the coastal Beaufort Sea, Canadian Arctic Ocean, with a particular focus on free-living vs. particle-attached communities. Capillary electrophoresis-single strand conformation polymorphism (CE-SSCP) showed significant differences when comparing river, coast and open sea bacterial community structures. In contrast to the river and coastal waters, total (16S rDNA-based) and active (16S rRNA-based) communities in the open sea samples were not significantly different, suggesting that most present bacterial groups were equally active in this area. Additionally, we observed significant differences between particle-attached (PA) and free-living (FL) bacterial communities in the open sea, but similar structure in the two fractions for coastal and river samples. Direct multivariate statistical analyses showed that total community structure was mainly driven by salinity (proxy of DOC and CDOM), suspended particles, amino acids and chlorophyll a . 16S rRNA genes pyrosequencing of selected samples confirmed these significant differences from river to sea and also between PA and FL fractions only in open sea samples, and PA samples generally showed higher diversity (Shannon, Simpson and Chao indices) than FL samples. At the class level, Opitutae was most abundant in the PA fraction of the sea sample, followed by Flavobacteria and Gammaproteobacteria , while the FL sea sample was dominated by Alphaproteobacteria . Finally, the coast and river samples, both PA and FL fractions, were dominated by Betaproteobacteria , Alphaproteobacteria and Actinobacteria . These results highlight the coexistence of particle specialists and generalists and the role of particle quality in structuring bacterial communities in the area. These results may also serve as a~basis to predict further changes in bacterial communities should climate change lead to further increases in river discharge and related particles load.

Beschreibung: F. S. Costa and E. Capelas de Oliveira We study a time-space fractional wave-diffusion equation with periodic conditions using Laplace transforms and Fourier series and presenting its solution in terms of three-parameter Mittag-Leffler functions. As a particular case we recover a recent result. We also present some graphics associated wi ... [J. Math. Phys. 53, 123520 (2012)] published Mon Dec 10, 2012.

Beschreibung: Paolo Amore We show that the spectral zeta functions of inhomogeneous strings and drums can be calculated using Rayleigh-Schrodinger perturbation theory. The inhomogeneities that can be treated with this method are small but otherwise arbitrary and include the previously studied case of a piecewise constant den ... [J. Math. Phys. 53, 123519 (2012)] published Mon Dec 10, 2012.

Beschreibung: Caidi Zhao This paper studies the pullback asymptotic behavior of solutions for a non-autonomous non-Newtonian fluid on Omega=[openface R] x (L,L) for some L 〉 0. We first use the technique of truncation functions together with the decomposition of spatial domain to prove the existence of a pullback attractor ... [J. Math. Phys. 53, 122702 (2012)] published Mon Dec 10, 2012.

Beschreibung: Ashley Montanaro Hypercontractive inequalities have become important tools in theoretical computer science and have recently found applications in quantum computation. In this note we discuss how hypercontractive inequalities, in various settings, can be used to obtain (fairly) concise proofs of several results in q ... [J. Math. Phys. 53, 122206 (2012)] published Mon Dec 10, 2012.

Beschreibung: S. S. Man'ko We study Schrodinger operators on star metric graphs with potentials of the form alpha[eh]Q([eh]x). In dimension 1 such potentials, with additional assumptions on Q, approximate in the sense of distributions as [eh] --〉 0 the first derivative of the Dirac delta-function. We establish the convergence ... [J. Math. Phys. 53, 123521 (2012)] published Mon Dec 10, 2012.

Beschreibung: Physical and biogeochemical forcing of oxygen changes in the tropical eastern South Pacific along 86° W: 1993 versus 2009 Biogeosciences Discussions, 9, 17583-17618, 2012 Author(s): P. J. Llanillo, J. Karstensen, J. L. Pelegrí, and L. Stramma Temporal changes of the water mass distribution and biogeochemical cycling in the tropical eastern South Pacific are investigated based on the extended Optimum Multi-Parameter (OMP) method. Two ship occupations of a meridional section along 85°50´ W, from 14° S to 1° N, are analysed, one during a relatively warm (El Niño/El Viejo, March 1993) and the other during a cold (La Niña/La Vieja, February 2009) upper-ocean phase. The largest El Niño – Southern Oscillation (ENSO) impact was found in the water properties and water mass distribution in the upper 250 m. The most prominent change is the vertical motion of the Oxygen Minimum Zone (OMZ) associated to the hypoxic Equatorial Subsurface Water (ESSW). During a cold phase the core of the ESSW is found at shallower layers, replacing the shallow (top 250 m) Subtropical Surface Water (STW) and allowing an intrusion of oxygen-rich and nutrient-poor Antarctic Intermediate Water (AAIW) in the depth range of 300 to 600 m. The shift in the vertical location of the intrusion of AAIW in the OMZ induces changes in oxygen advection and respiration, the largest the oxygen supply the greatest the respiration and the lowest the nitrate loss by denitrification. Changes in the intensity of the zonal currents in the Equatorial Current System, that ventilate the OMZ from the west, are used to explain the patchy latitudinal changes of seawater properties observed along the repeated section. Given that changes down to 800 m depth are observed, not only interannual (ENSO) but also decadal variability (Pacific Decadal Oscillation) is a potential driver for the observed changes.

Beschreibung: Benthic communities in the deep Mediterranean Sea: exploring microbial and meiofaunal patterns in slope and basin ecosystems Biogeosciences Discussions, 9, 17539-17581, 2012 Author(s): K. Sevastou, N. Lampadariou, P. N. Polymenakou, and A. Tselepides The long held perception of the deep sea consisting of monotonous slopes and uniform oceanic basins has over the decades given way to the idea of a complex system with wide habitat heterogeneity. Under the prism of a highly diverse environment, a large dataset was used to describe and compare spatial patterns of the dominant small-size components of deep-sea benthos, metazoan meiofauna and bacteria, from Mediterranean basins and slopes. A grid of 73 stations sampled at five geographical areas along the central-eastern Mediterranean basin (central Mediterranean, northern Aegean Sea, Cretan Sea, Libyan Sea, eastern Levantine) spanning over 4 km in depth revealed a high diversity in terms of both metazoan meiofauna and microbial communities. The higher meiofaunal abundance and richness observed in the northern Aegean Sea highlights the effect of productivity on benthic patterns. Non parametric analyses detected no differences for meiobenthic standing stocks and major taxa diversity ( α , β , γ and δ components) between the two habitats (basin vs. slope) for the whole investigated area and within each region, but revealed significant bathymetric trends: abundance and richness follow the well-known gradient of decreasing values with increasing depth, whereas differentiation diversity ( β - and δ -diversity) increases with depth. In spite of a similar bathymetric trend observed for nematode genera richness, no clear pattern was detected with regard to habitat type; the observed number of nematode genera suggests higher diversity in slopes, whereas richness estimator Jack1 found no differences between habitats. On the other hand, δ -diversity was higher at the basin habitat, but no differences were found among depth ranges, though turnover values were high in all pairwise comparisons of the different depth categories. Results of multivariate analysis are in line with the above findings, indicating high within habitat variability of meiofaunal communities and a gradual change of meiofaunal structure towards the abyssal stations. In contrast to meiobenthic results, microbial richness is significantly higher at the basin ecosystem and tends to increase with depth, while community structure varies greatly among samples regardless of the type of habitat, depth or area. The results presented here suggest that differences in benthic parameters between the two habitats are neither strong nor consistent; it appears that within habitat variability is high and differences among depth ranges are more important.

Beschreibung: Giuseppe Genovese In this work, we give a proof of universality with respect to the choice of the statistical distribution of the quenched noise, for mean field bipartite spin glasses. We use mainly techniques of spin glasses theory, as Guerra's interpolation and the cavity approach. ... [J. Math. Phys. 53, 123304 (2012)] published Wed Dec 5, 2012.

Beschreibung: Air-sea exchange of CO 2 at a Northern California coastal site along the California Current upwelling system Biogeosciences Discussions, 9, 17707-17741, 2012 Author(s): H. Ikawa, I. Faloona, J. Kochendorfer, K. T. Paw U, and W. C. Oechel Uncertainty in the air-sea CO 2 exchange (CO 2 flux) in coastal upwelling zones is attributed to high temporal variability, which is caused by changes in ocean currents. Upwelling transports heterotrophic, CO 2 enriched water to the surface and releases CO 2 to the atmosphere, whereas the presence of nutrient-rich water at the surface supports high primary production and atmospheric CO 2 uptake. To quantify the effects of upwelling on CO 2 fluxes, we measured CO 2 flux at a coastal upwelling site off of Bodega Bay, California, during the summer of 2007 and the fall of 2008 using the eddy covariance technique and the bulk method with p CO 2 measurements from November 2010 to July 2011. Variations in sea surface temperatures (SST) and alongshore wind speeds suggest that the measurement period in 2007 coincided with a typical early-summer upwelling period and the measurement period in 2008 was during a typical fall relaxation period. A strong source of CO 2 (~1.5 ± 7 SD (standard deviation) g C m −2 day −1 ) from the ocean to the atmosphere during the upwelling period was concurrent with high salinity, low SST, and low chlorophyll density. In contrast, a weak source of CO 2 flux (~0.2 ± 3 SD g C m −2 day −1 ) was observed with low salinity, high SST and high chlorophyll density during the relaxation period. Similarly, the sink and source balance of CO 2 flux was highly related to salinity and SST during the p CO 2 measurement periods; high salinity and low SST corresponded to high p CO 2 , and vice versa. We estimated that the coastal area off Bodega Bay was likely a source of CO 2 to the atmosphere based on the following conclusions: (1) the overall CO 2 flux estimated from both eddy covariance and p CO 2 measurements showed a source of CO 2 ; (2) although the relaxation period during the 2008 measurements were favorable to CO 2 uptake, CO 2 flux during this period was still a slight source, (3) salinity and SST were found to be good predictors of the CO 2 flux for both eddy covariance and p CO 2 measurements, and historical data of daily averaged SST and salinity between 1988 to 2011 show that 99% of the data falls within the range of our observation in May–June 2007, August–September 2008 and November 2010–July 2011 indicating that our data set was representative of the annual variations in the sea state. Based on the developed relationship between p CO 2 and SST and salinity, the average annual CO 2 flux between 1988 and 2011 was estimated to be ~35 mol C m −2 yr −1 . The peak monthly CO 2 flux of ~7 mol C m −2 month −1 accounted for about 30% of the dissolved inorganic carbon in the surface mixed-layer.

Beschreibung: Trophic state of sediments from two deep continental margins off Iberia: a biomimetic approach Biogeosciences Discussions, 9, 17619-17650, 2012 Author(s): A. Dell'Anno, A. Pusceddu, C. Corinaldesi, M. Canals, S. Heussner, L. Thomsen, and R. Danovaro The trophic state of benthic deep-sea ecosystems can greatly influence key ecological processes (e.g. biomass production and nutrient cycling). Thus, assessing the trophic state of the sediment at different spatial and temporal scales is crucial for a better understanding of deep-sea ecosystem functioning. Here, using a biomimetic approach based on enzymatic digestion of protein and carbohydrate pools, we assess the bioavailability of organic detritus and its nutritional value in the uppermost layer of deep-sea sediments from open slopes and canyons of the Catalan (NW Mediterranean) and Portuguese (NE Atlantic) continental margins, offshore east and west Iberia, respectively. Patterns of sediment trophic state were analyzed in relation to increasing water depth, including repeated samplings over a 3 yr period in the Catalan margin. Bioavailable organic matter and its nutritional value were significantly higher in the Portuguese margin than in the Catalan margin, thus reflecting differences in primary productivity of surface waters reported for the two regions. Similarly, sediments of the Catalan margin were characterized by significantly higher food quantity and quality in spring, when higher primary production processes occur in surface waters, than in summer and autumn. In both continental margins, bioavailable organic C concentrations did not vary or increase with increasing water depth. Differences in the benthic trophic state of canyons against open slopes were more evident in the Portuguese than in the Catalan margin. Overall our findings indicate that deep-sea sediments are characterized by relatively high amounts of bioavailable organic matter. We suggest that the interactions between biological-related processes in surface waters and particle transport and deposition dynamics can play a crucial role in shaping the quantity and distribution of bioavailable organic detritus and its nutritional value along deep continental margins.

Beschreibung: Koenraad M. R. Audenaert, Milan Mosonyi, and Frank Verstraete In the problem of quantum state discrimination, one has to determine by measurements the state of a quantum system, based on the a priori side information that the true state is one of the two given and completely known states, rho or sigma. In general, it is not possible to decide the identity of t ... [J. Math. Phys. 53, 122205 (2012)] published Fri Dec 7, 2012.

Beschreibung: Effects of increased p CO 2 and geographic origin on purple sea urchin ( Strongylocentrotus purpuratus ) calcite elemental composition Biogeosciences Discussions, 9, 17939-17973, 2012 Author(s): M. LaVigne, T. M. Hill, E. Sanford, B. Gaylord, A. D. Russell, E. A. Lenz, J. D. Hosfelt, and M. K. Young Ocean acidification will likely have negative impacts on invertebrates producing skeletons composed of calcium carbonate. Skeletal solubility is partly controlled by the incorporation of "foreign" ions (such as Mg and Sr) into the crystal lattice of these skeletal structures, a process that is sensitive to a variety of biological and environmental factors. Here we explore the effects of life stage, oceanographic region of origin, and changes in the partial pressure of carbon dioxide in seawater ( p CO 2 ) on trace elemental composition in the purple sea urchin ( Strongylocentrotus purpuratus ). We show that, similar to other urchin taxa, adult purple sea urchins have the ability to precipitate skeleton composed of a range of biominerals spanning low to high magnesium calcites. Mg/Ca and Sr/Ca ratios were substantially lower in adult spines compared to adult tests. On the other hand, trace elemental composition was invariant among adults collected from four oceanographically distinct regions along the US west coast (Oregon, Northern California, Central California, and Southern California). Skeletons of newly settled juvenile urchins that originated from adults from the four regions exhibited intermediate Mg/Ca and Sr/Ca between adult spine and test endmembers, indicating that skeleton precipitated during early life stages is more soluble than adult spines and less soluble than adult tests. Mean skeletal Mg/Ca or Sr/Ca of juvenile skeleton did not vary with source region when larvae were reared under present-day, global-average seawater carbonate conditions (400 ppm; pH = 8.02 ± 0.03 1 SD; Ω calcite = 3.3 ± 0.2 1 SD). However, when reared under elevated CO 2 (900 ppm; pH = 7.72 ± 0.03; Ω calcite = 1.8 ± 0.1), skeletal Sr/Ca in juveniles exhibited increased variance across the four regions. Although larvae from the northern populations (Oregon, Northern California, Central California) did not exhibit differences in Mg or Sr incorporation under elevated CO 2 (Sr/Ca = 2.09 ± 0.06 mmol mol −1 ; Mg/Ca = 66.9 ± 4.1 mmol mol −1 ), juveniles of Southern California origin partitioned ∼ 8% more Sr into their skeletons when exposed to higher CO 2 (Sr/Ca = 2.26 ± 0.05 vs. 2.10 ± 0.03 mmol mol −1 1 SD). Together these results suggest that the diversity of carbonate minerologies present across different skeletal structures and life stages in purple sea urchins does not translate into an equivalent plasticity of response associated with geographic variation or temporal shifts in seawater properties. Rather, composition of S. purpuratus skeleton precipitated during both early and adult life history stages appears relatively robust to spatial gradients and predicted changes in seawater carbonate chemistry for 2100. An exception to this trend may arise during early life stages, where certain populations of purple sea urchins may alter skeletal mineral precipitation rates and composition beyond a given CO 2 threshold. The degree to which this latter geochemical plasticity might affect mineral stability and solubility in a future, altered ocean requires additional study.

Beschreibung: Ewa Felinska, Zbigniew Jaskolski, and Michal Kosztolowicz A flow in the formulation and proof of Lemma 2.7 of E. Felinska, Z. Jaskolski, and M. M. Kosztolowicz, J. Math. Phys. 53, 033504 (2012) is fixed in Sec. I of this Erratum. This has no consequences for the rest of the paper. An essential error was made in Theorems 3.5, 3.6, and Corollary 3.7 of Sec. ... [J. Math. Phys. 53, 129902 (2012)] published Fri Dec 14, 2012.

Beschreibung: K. Deschout and A. B. J. Kuijlaars We consider Angelesco ensembles with respect to two modified Jacobi weights on touching intervals [a, 0] and [0, 1], for a 〈 0. As a --〉 1 the particles around 0 experience a phase transition. This transition is studied in a double scaling limit, where we let the number of particles of the ensemble ... [J. Math. Phys. 53, 123523 (2012)] published Fri Dec 14, 2012.

Beschreibung: Rong Cheng, Jianhua Hu, and Zhiyong Wang In this paper, we study a class of semilinear elliptic equations which are completely resonant with nonconstant coefficients at origin and at infinity. By applying Morse theory and Minimax method, we obtain the existence of multiple nontrivial solutions for the equations. ... [J. Math. Phys. 53, 123524 (2012)] published Fri Dec 14, 2012.

Beschreibung: Bioavailability of sinking organic matter in the Blanes canyon and the adjacent open slope (NW Mediterranean Sea) Biogeosciences Discussions, 9, 18295-18330, 2012 Author(s): P. Lopez-Fernandez, S. Bianchelli, A. Pusceddu, A. Calafat, A. Sanchez-Vidal, and R. Danovaro Submarine canyons are sites of intense energy and material exchange between the shelf and the deep adjacent basins. To test the hypothesis that active submarine canyons represent preferential conduits of available food for the deep-sea benthos, two mooring lines were deployed at 1200 m depth from November 2008 to November 2009 inside the Blanes canyon and on the adjacent open slope (Catalan Margin, NW Mediterranean Sea). We investigated the fluxes, biochemical composition and food quality of sinking organic carbon (OC). OC fluxes in the canyon and the open slope varied among sampling periods, though not consistently in the two sites. In particular, while in the open slope the highest OC fluxes were observed in August 2009, in the canyon the highest OC fluxes occurred in April–May 2009. For almost the entire study period, the OC fluxes in the canyon were significantly higher than those in the open slope, whereas OC contents of sinking particles collected in the open slope were consistently higher than those in the canyon. This result confirms that submarine canyons are effective conveyors of OC to the deep sea, particles transferred are predominantly of inorganic origin, significantly higher than that reaching the open slope at a similar water depth. Using multivariate statistical tests, two major clusters of sampling periods were identified: one in the canyon that grouped trap samples collected in December 2008, concurrently with the occurrence of a major storm at the sea surface, and associated with increased fluxes of nutritionally available particles from the upper shelf. Another cluster grouped samples from both the canyon and the open slope collected in March 2009, concurrently with the occurrence of the seasonal phytoplankton bloom at the sea surface, and associated with increased fluxes of total phytopigments. Our results confirm the key ecological role of submarine canyons for the functioning of deep-sea ecosystems, and highlight the importance of canyons in linking episodic storms and primary production occurring at the sea surface to the deep sea floor.

Beschreibung: Influence of increasing dissolved inorganic carbon concentrations and decreasing pH on chemolithoautrophic bacteria from oxic-sulfidic interfaces Biogeosciences Discussions, 9, 18371-18395, 2012 Author(s): K. Mammitzsch, G. Jost, and K. Jürgens Increases in the dissolved inorganic carbon (DIC) concentration are expected to cause a decrease in the pH of ocean waters, a process known as ocean acidification. In oxygen-deficient zones this will add to already increased DIC and decreased pH values. It is not known how this might affect microbial communities and microbially mediated processes. In this study, the potential effects of ocean acidification on chemolithoautotrophic prokaryotes of marine oxic-anoxic transition zones were investigated, using the chemoautotrophic denitrifying ε -proteobacterium " Sulfurimonas gotlandica " strain GD1 as a model organism. This and related taxa use reduced sulfur compounds, e.g. sulfide and thiosulfate, as electron donors and were previously shown to be responsible for nitrate removal and sulfide detoxification in redox zones of the Baltic Sea water column but occur also in other oxygen-deficient marine systems. Bacterial cell growth within a broad range of DIC concentrations and pH values was monitored and substrate utilization was determined. The results showed that the DIC saturation concentration for growth was already reached at 800 μM, which is well below in situ DIC levels. The pH optimum was between 6.6 and 8.0. Within a pH range of 6.6–7.1 there was no significant difference in substrate utilization; however, at lower pH values cell growth decreased sharply and cell-specific substrate consumption increased. These findings suggest that a direct effect of ocean acidification, with the predicted changes in pH and DIC, on chemolithoautotrophic bacteria such as " S. gotlandica " str. GD1 is generally not very probable.

Beschreibung: Linyu Peng, Huafei Sun, and Guoquan Xu The complexity of the fractional Brownian motions is investigated from the viewpoint of information geometry. By introducing a Riemannian metric on the space of their power spectral densities, the geometric structure is achieved. Based on the general construction, for an example, whose power spectra ... [J. Math. Phys. 53, 123305 (2012)] published Mon Dec 17, 2012.

Beschreibung: Microbial bioavailability regulates organic matter preservation in marine sediments Biogeosciences Discussions, 9, 13187-13210, 2012 Author(s): K. A. Koho, K. G. J. Nierop, L. Moodley, J. J. Middelburg, L. Pozzato, K. Soetaert, J. van der Plicht, and G.-J. Reichart Burial of organic matter (OM) plays an important role in marine sediments, linking the short-term, biological carbon cycle with the long-term, geological subsurface cycle. It is well established that low-oxygen conditions promote organic carbon burial in marine sediments. However, the mechanism remains enigmatic. Here we report biochemical quality, microbial degradability, OM preservation and accumulation along an oxygen gradient in the Indian Ocean. Our results show that more OM, and of biochemically higher quality, accumulates under low oxygen conditions. Nevertheless, microbial degradability does not correlate with the biochemical quality of OM. This decoupling of OM biochemical quality and microbial degradability, or bioavailability, violates the ruling paradigm that higher quality implies higher microbial processing. The inhibition of bacterial OM remineralisation may play an important role in the burial of organic matter in marine sediments and formation of oil source rocks.

Beschreibung: Impact of an 8.2-kyr-like event on methane emissions in northern peatlands Biogeosciences Discussions, 9, 13243-13286, 2012 Author(s): S. Zürcher, R. Spahni, F. Joos, M. Steinacher, and H. Fischer Rapid changes in atmospheric methane (CH 4 ), temperature and precipitation are documented by Greenland ice core data both for glacial times (the so called Dangaard-Oeschger (DO) events) as well as for a cooling event in the early Holocene (the 8.2 kyr event). The onsets of DO warm events are paralleled by abrupt increases in CH 4 by up to 250 ppbv in a few decades. Vice versa, the 8.2 kyr event is accompanied by an intermittent decrease in CH 4 of about 80 ppbv over 150 yr. The abrupt CH 4 changes are thought to mainly originate from source emission variations in tropical and boreal wet ecosystems, but complex process oriented bottom-up model estimates of the changes in these ecosystems during rapid climate changes are still missing. Here we present simulations of CH 4 emissions from northern peatlands with the LPJ-Bern dynamic global vegetation model. The model represents CH 4 production and oxidation in soils and transport by ebullition, through plant aerenchyma, and by diffusion. Parameters are tuned to represent site emission data as well as inversion-based estimates of northern wetland emissions. The model is forced with climate input data from freshwater hosing experiments using the NCAR CSM1.4 climate model to simulate an abrupt cooling similar to the widespread 8.2 kyr event. As a main result we get a concentration reduction of ~10 ppbv per degree K change of mean northern hemispheric surface temperature in peatlands. This sensitivity comprises effects on peatland emissions of similar size by the temperature itself as well as by the accompanying change in precipitation rate, hence water table. Comparison with the ice core record reveals that a change in boreal peatland emissions alone could not completely account for the 80 ppbv methane decline during the 8.2 kyr event, pointing to a significant contribution from tropical wetlands to this event.

Beschreibung: Temporal variation of nitrate and phosphate transport in headwater catchments: the hydrological controls and landuse alteration Biogeosciences Discussions, 9, 13211-13241, 2012 Author(s): T.-Y. Lee, J.-C. Huang, S.-J. Kao, and C.-P. Tung Oceania Rivers are hotspots of high DIN (dissolved inorganic nitrogen) and DIP (dissolved inorganic phosphorus) transport. However, the effects of hydrologic controls and land use alternation on the temporal variations of DIN and DIP are rarely documented. In this study, we monitored the nitrate and phosphate concentrations from three headwater catchments with different cultivation gradients at a 3-day interval. This sampling scheme was supplemented with a 3-h interval monitoring during typhoon periods. The results showed that the DIN and DIP yields in the pristine, moderately cultivated, and intensively cultivated watersheds were 7.52/0.31, 31.17/0.30, and 40.96/0.52 kg ha −1 yr −1 , respectively. The high DIN yields are comparable to the intensively and extensively disturbed large rivers around the world. These N yields may be due to a high level of nitrogen deposition, rainfall-runoff, and fertilizer application. The importance of event sampling was indicated by the contribution of the three typhoons to the annual DIN and DIP fluxes, which were 30% and 60%, respectively. Both DIN and DIP fluxes significantly increased as the cultivation gradient increased. The DIN and DIP ratio varied from 54 to 230 depending on the decrease of the cultivation gradient. This value is higher than the global mean of ~18. Thus, we speculate that nitrogen saturation occurs in the headwater catchments of Oceania Rivers. The results obtained provide fundamental clues of DIN and DIP yield of Oceania Rivers, which are helpful in understanding the impact of human disturbance on headwater watersheds.

Beschreibung: Ammonia emissions from cattle urine and dung excreted on pasture Biogeosciences Discussions, 9, 13287-13318, 2012 Author(s): J. Laubach, A. Taghizadeh-Toosi, S. J. Gibbs, R. R. Sherlock, F. M. Kelliher, and S. P. P. Grover Twelve cattle were kept for three days in a circular area of 16 m radius on short pasture and fed with freshly-cut pasture. Ammonia (NH 3 ) emissions from the urine and dung excreted by the cattle were measured with a micrometeorological mass-balance method, during the cattle presence and for 10 subsequent days. Daily-integrated emission rates peaked on day 3 of the experiment (last day of cattle presence) and declined steadily for five days thereafter. Urine patches were the dominant sources for these emissions. On day 9, a secondary emissions peak occurred, with dung pats likely to be the main sources. This interpretation is based on simultaneous observations of the pH evolution in urine patches and dung pats created next to the circular plot. Feed and dung samples were analysed to estimate the amounts of nitrogen (N) ingested and excreted. Total N volatilised as NH 3 was 19.8 (±0.9) % of N intake and 22.4 (±1.3) % of N excreted. The bimodal shape of the emissions time series allowed to infer separate estimates for volatilisation from urine and dung, respectively, with the result that urine accounted for 88.6 (±2.6) % of the total NH 3 emissions. The emissions from urine represented 25.5 (±2.0) % of the excreted urine-N, while the emissions from dung amounted to 11.6 (±2.7) % of the deposited dung-N. Emissions from dung may have continued after day 13 but were not resolved by the measurement technique. A simple resistance model shows that the magnitude of the emissions from dung is controlled by the resistance of the dung crust.

Beschreibung: Isoprene emissions from a tundra ecosystem Biogeosciences Discussions, 9, 13351-13396, 2012 Author(s): M. J. Potosnak, B. M. Baker, L. LeStourgeon, S. M. Disher, K. L. Griffin, and M. S. Bret-Harte Whole-system fluxes of isoprene from a~moist acidic tundra ecosystem and leaf-level emission rates of isoprene from a common species ( Salix pulchra ) in that same ecosystem were measured during three separate field campaigns. The field campaigns were conducted during the summers of 2005, 2010 and 2011 and took place at the Toolik Field Station (68.6° N, 149.6° W) on the north slope of the Brooks Range in Alaska, USA. The maximum rate of whole-system isoprene flux measured was over 1.2 mg C m −2 h −1 with an air temperature of 22 ° C and a PAR level over 1500 μmol m −2 s −1 . Leaf-level isoprene emission rates for S. pulchra averaged 12.4 nmol m −2 s −1 (27.4 μg C gdw −1 h −1 ) extrapolated to standard conditions (PAR = 1000 μmol m −2 s −1 and leaf temperature = 30° C). Leaf-level isoprene emission rates were well characterized by the Guenther algorithm for temperature, but less so for light. Chamber measurements from a nearby moist acidic tundra ecosystem with less S. pulchra emitted significant amounts of isoprene, but at lower rates (0.45 mg C m −2 h −1 ). Comparison of our results to predictions from a global model found broad agreement, but a detailed analysis revealed some significant discrepancies. An atmospheric chemistry box model predicts that the observed isoprene emissions have a significant impact on Arctic atmospheric chemistry, including the hydroxyl radical (OH). Our results support the prediction that isoprene emissions from Arctic ecosystems will increase with global climate change.

Beschreibung: Seasonal measurements of total OH reactivity fluxes, total ozone loss rates and missing emissions from Norway spruce in 2011 Biogeosciences Discussions, 9, 13497-13536, 2012 Author(s): A.C. Nölscher, E. Bourtsoukidis, B. Bonn, J. Kesselmeier, J. Lelieveld, and J. Williams Numerous reactive volatile organic compounds (VOCs) are emitted into the atmosphere by vegetation. Most biogenic VOCs are highly reactive towards the atmosphere's most important oxidant, the hydroxyl (OH) radical. One way to investigate the chemical interplay between biosphere and atmosphere is through the measurement of total OH reactivity, the total loss rate of OH radicals. This study presents the first determination of total OH reactivity emission rates (measurements via the Comparative Reactivity Method) based on a branch cuvette enclosure system mounted on a Norway spruce (Picea abies) throughout spring, summer and autumn 2011. In parallel separate VOC emission rates were monitored by a Proton Transfer Reaction-Mass Spectrometer (PTR-MS), and total ozone (O 3 ) loss rates were obtained inside the cuvette. Total OH reactivity emission rates were in general temperature and light dependent, showing strong diel cycles with highest values during daytime. Monoterpene emissions contributed most, accounting for 56–69% of the measured total OH reactivity flux in spring and early summer. However, during late summer and autumn the monoterpene contribution decreased to 11–16%. At this time, a large missing fraction of the total OH reactivity emission rate (70–84%) was found when compared to the VOC budget measured by PTR-MS. Total OH reactivity and missing total OH reactivity emission rates reached maximum values in late summer corresponding to the period of highest temperature. Total O 3 loss rates within the closed cuvette showed similar diel profiles and comparable seasonality to the total OH reactivity fluxes. Total OH reactivity fluxes were also compared to emissions from needle storage pools predicted by a temperature-only dependent algorithm. Deviations of total OH reactivity fluxes from the temperature-only dependent emission algorithm were observed for occasions of mechanical and heat stress. While for mechanical stress, induced by strong wind, measured VOCs could explain total OH reactivity emissions, during heat stress they could not. The temperature driven algorithm matched the diel course much better in spring than in summer, indicating a different production and emission scheme for summer and early autumn. During these times, unmeasured and possibly unknown primary biogenic emissions contributed significantly to the observed total OH reactivity flux.

Beschreibung: Increasing cloudiness in Arctic damps the increase in phytoplankton primary production due to sea ice receding Biogeosciences Discussions, 9, 13987-14012, 2012 Author(s): S. Bélanger, M. Babin, and J.-E. Tremblay The Arctic Ocean and its marginal seas are among the marine regions most affected by climate change. Here we present the results of a diagnostic model used to elucidate the main drivers of primary production (PP) trends over the 1998–2010 period at pan-Arctic and local (i.e. 9.28 km resolution) scales. Photosynthetically active radiation (PAR) above and below the sea surface was estimated using precomputed look-up tables of spectral irradiance and satellite-derived cloud optical thickness and cloud fraction parameters from the International Satellite Cloud Climatology Project (ISCCP) and sea ice concentration from passive microwaves data. A spectrally resolved PP model, designed for optically complex waters, was then used to produce maps of PP trends. Results show that incident PAR above the sea surface (PAR(0+)) has significantly decreased over the whole Arctic and sub-Arctic Seas, except over the perrennially sea ice covered waters of the Central Arctic Ocean. This fading of PAR(0+) (+8% decade –1 ) was caused by increasing cloudiness May and June. Meanwhile PAR penetrating the ocean (PAR(0–)) increased only along the sea ice margin over the large Arctic continental shelf where sea ice concentration declined sharply since 1998. Overall, PAR(0–) slightly increased in the Circum Arctic (+3.4% decade –1 ), while it decreased when considering both Arctic and sub-Arctic Seas (–3% decade –1 ). We showed that rising phytoplankton biomass (i.e. chlorophyll a ) normalized by the diffuse attenuation of photosynthetically usable radiation (PUR) by phytoplankton accounted for a larger proportion of the rise in PP than did the increase in light availability due to sea-ice loss in several sectors and particularly in perrennially and seasonally open waters. Against a general backdrop of rising productivity over Arctic shelves, significant negative trends were observed in regions known for their great biological importance such as the coastal polynyas of Northern Greenland.

Beschreibung: Jean-Claude Saut, Roger Temam, and Chuntian Wang Motivated by the study of boundary control problems for the Zakharov-Kuznetsov equation, we study in this article the initial and boundary value problem for the ZK (short for Zakharov-Kuznetsov) equation posed in a limited domain Omega = (0, 1) x (pi/2, pi/2), d = 1, 2. This article is related to ... [J. Math. Phys. 53, 115612 (2012)] published Fri Oct 12, 2012.

Beschreibung: Darryl D. Holm and Cesare Tronci The Euler-Poincare approach to complex fluids is used to derive multiscale equations for computationally modeling Euler flows as a basis for modeling turbulence. The model is based on a kinematic sweeping ansatz (KSA) which assumes that the mean fluid flow serves as a Lagrangian frame of motion for ... [J. Math. Phys. 53, 115614 (2012)] published Fri Oct 12, 2012.

Beschreibung: R. Dascaliuc and Z. Grujic A mathematical evidencein a statistically significant senseof a geometric scenario leading to criticality of the Navier-Stokes problem is presented. ... [J. Math. Phys. 53, 115613 (2012)] published Fri Oct 12, 2012.

Beschreibung: Weinan E and Jianfeng Lu The continuum limit of the spin-polarized Thomas-Fermi-Dirac-von Weizsacker model in an external magnetic field is studied. An extension of the classical Cauchy-Born rule for crystal lattices is established for the electronic structure under sharp stability conditions on charge density and spin dens ... [J. Math. Phys. 53, 115615 (2012)] published Fri Oct 12, 2012.

Beschreibung: Storage and stability of organic carbon in soils as related to depth, occlusion within aggregates, and attachment to minerals Biogeosciences Discussions, 9, 13085-13133, 2012 Author(s): M. Schrumpf, K. Kaiser, G. Guggenberger, T. Persson, I. Kögel-Knabner, and E.-D. Schulze Conceptual models suggest that stability and age of organic carbon (OC) in soil depends on the source of plant litter, occlusion within aggregates, incorporation in organo-mineral complexes, and location within the soil profile. Various tools like density fractionation, mineralization experiments, and radiocarbon analyses have been used to study the importance of these mechanisms. We systematically apply them to a range of European soils to test whether general controls emerge even for soils that vary in vegetation, soil types, parent material, and land use. At each of the 12 study sites, 10 soil cores were sampled in 10 cm depth intervals to 60 cm depth and subjected to density separation. Bulk soil samples and density fractions (free light fractions – fLF, occluded light fractions – oLF, heavy fractions – HF) were analysed for OC, total nitrogen (TN), δ 13 C, and Δ 14 C. Bulk samples were also incubated to determine mineralizable OC. Declining OC-normalized CO 2 release and increasing age with soil depth confirm greater stability of OC in subsoils across sites. Depth profiles of LF-OC matched those of roots, which in turn reflect plant functional types in soil profiles not subject to ploughing. Modern Δ 14 C signatures and positive correlation between mineralizable C and fLF-OC indicate the fLF is an easily available energy and nutrient source for subsurface microbes. Fossil C derived from the geogenic parent material affected the age of OC especially in the LF at three study sites. The overall importance of OC stabilization by binding to minerals was demonstrated by declining OC-normalized CO 2 release rates with increasing contributions of HF-OC to bulk soil OC and the low Δ 14 C values of HF-OC. The stability of HF-OC was greater in subsoils than in topsoils; nevertheless, a portion of HF-OC was active throughout the profile. The decrease in Δ 14 C (increase in age) of HF-OC with soil depth was related to soil pH as well as to dissolved OC fluxes. This indicates that dissolved OC translocation contributes to the formation of subsoil HF-OC and shapes the Δ 14 C profiles. While quantitatively less important than OC in the HF, consistent older ages of oLF-OC than fLF-OC indicate that occlusion of LF-OC in aggregates also contributes to OC stability in subsoils. Overall, our results showed that association with minerals is the most important factor in stabilization of OC in soils.

Beschreibung: The non-steady-state oceanic CO 2 signal: its importance, magnitude and a novel way to detect it Biogeosciences Discussions, 9, 13161-13186, 2012 Author(s): B. I. McNeil and R. J. Matear The ocean's role has been pivotal in modulating rising atmospheric CO 2 levels since the industrial revolution, sequestering over a quarter of all fossil-fuel derived CO 2 emissions. Net oceanic uptake of CO 2 has roughly doubled between the 1960's (~1 Pg C yr −1 ) and 2000's (~2 Pg C yr −1 ), with expectations it will continue to absorb even more CO 2 with rising future atmospheric CO 2 levels. However, recent CO 2 observational analyses along with numerous model predictions suggest the rate of oceanic CO 2 uptake is already slowing, largely as a result of a natural decadal-scale outgassing signal. This recent and unexpected CO 2 outgassing signal represents a paradigm-shift in our understanding of the oceans role in modulating atmospheric CO 2 . Current tracer-based estimates for the ocean storage of anthropogenic CO 2 assume the ocean circulation and biology is in steady state, thereby missing the new and potentially important "non-steady-state" CO 2 outgassing signal. By combining data-based techniques that assume the ocean is in steady-state, with techniques that constrain the net oceanic CO 2 uptake signal, we show how to extract the non-steady-state CO 2 signal from observations. Over the entire industrial era, the non-steady-state CO 2 outgassing signal (~13 ± 10 Pg C) is estimated to represent about 9% of the total net CO 2 inventory change (~142 Pg C). However between 1989 and 2007, the non-steady-state CO 2 outgassing signal (~6.3 Pg C) has likely increased to be ~18% of net oceanic CO 2 storage over that period (~36 Pg C), a level which cannot be ignored. The present uncertainty of our data-based techniques for oceanic CO 2 uptake limit our capacity to quantify the non-steady-state CO 2 signal, however with more data and better certainty estimates across a~range of diverse methods, this important and growing CO 2 signal could be better constrained in the future.

Beschreibung: Diversity pattern of nitrogen fixing microbes in nodules of Trifolium arvense (L.) at different initial stages of ecosystem development Biogeosciences Discussions, 9, 13135-13160, 2012 Author(s): S. Schulz, M. Engel, D. Fischer, F. Buegger, M. Elmer, G. Welzl, and M. Schloter Legumes can be considered as pioneer plants during ecosystem development, as they form a symbiosis with different nitrogen fixing rhizobia species, which enable the plants to grow on soils with low available nitrogen content. In this study we compared the abundance and diversity of nitrogen fixing microbes based on the functional marker gene nifH , which codes for a subunit of the Fe-protein of the dinitrogenase reductase, in nodules of different size classes of Trifolium arvense (L.). Additionally, carbon and nitrogen contents of the bulk soil and plant material were measured. Plants were harvested from different sites, reflecting 2 (2a) and 5 (5a) yr of ecosystem development, of an opencast lignite mining area in the south of Cottbus, Lower Lusatia (Germany) where the artificial catchment "Chicken Creek" was constructed to study the development of terrestrial ecosystems. Plants from the 5a site revealed higher amounts of carbon and nitrogen, although nifH gene abundances in the nodules and carbon and nitrogen contents between the two soils did not differ significantly. Analysis of the nifH clone libraries showed a significant effect of the nodule size on the community composition of nitrogen fixing microbes. Medium sized nodules (2–5 mm) contained a uniform community composed of Rhizobium leguminosarum bv. trifolii , whereas the small nodules ( 〈 2 mm) consisted of a diverse community including clones with non- Rhizobium nifH gene sequences. Regarding the impact of the soil age on the community composition a clear distinction between the small and the medium nodules can be made. While clone libraries from the medium nodules were pretty similar at both soil ages, soil age had a significant effect on the community compositions of the small nodules, where the proportion of R. leguminosarum bv. trifolii increased with soil age.

Beschreibung: Lizhi Ruan and Haiyan Yin The aim of this paper is to study the global unique solvability on C-solution to the Cauchy problem of a special 2 x 2 nonlinear hyperbolic system with damping and diffusion. Furthermore, we also investigate the convergence rates as the diffusion parameter beta goes to zero. It is shown that the c ... [J. Math. Phys. 53, 103703 (2012)] published Mon Sep 24, 2012.

Beschreibung: Ioana Dumitriu We compute the exact and limiting smallest eigenvalue distributions for two classes of beta-Jacobi ensembles not covered by previous studies. In the general beta case, these distributions are given by multivariate hypergeometric F functions, whose behavior can be analyzed asymptotically for special ... [J. Math. Phys. 53, 103301 (2012)] published Mon Sep 24, 2012.

Beschreibung: Carl M. Bender and Sarben Sarkar This paper presents an asymptotic analysis of the Boltzmann equations (Riccati differential equations) that describe the physics of thermal dark-matter-relic abundances. Two different asymptotic techniques are used, boundary-layer theory, which makes use of asymptotic matching, and the delta expansi ... [J. Math. Phys. 53, 103509 (2012)] published Thu Sep 27, 2012.

Beschreibung: K. Hepp This review provides many entry points to controversies in neuroscience, where input from mathematical physics could be fruitful, especially about coherence and decoherence in the brain, both on the level of classical and quantum mechanics. ... [J. Math. Phys. 53, 095222 (2012)] published Thu Sep 27, 2012.

Beschreibung: J. Kiukas, P. Lahti, J. Schultz, and R. F. Werner In the nonrelativistic setting with finitely many canonical degrees of freedom, a shift-covariant phase space observable is uniquely characterized by a positive operator of trace one and, in turn, by the Fourier-Weyl transform of this operator. We study three properties of such observables, and char ... [J. Math. Phys. 53, 102103 (2012)] published Thu Sep 27, 2012.

Beschreibung: Michael K.-H. Kiessling The non-relativistic bosonic ground state is studied for quantum N-body systems with Coulomb interactions, modeling atoms or ions made of N bosonic point electrons bound to an atomic point nucleus of Z absolute electron charges, treated in BornOppenheimer approximation (the nuclear mass M = [infinit ... [J. Math. Phys. 53, 095223 (2012)] published Thu Sep 27, 2012.

Beschreibung: N. Bebiano, J. da Providencia, and J. P. da Providencia Extensions of trace inequalities arising in statistical mechanics are derived in a straightforward and unified way from a variational characterization of the Tsallis entropy. Namely, one-parameter extension of the thermodynamic inequality is presented and its equivalence to a generalized PeierlsBogo ... [J. Math. Phys. 53, 103303 (2012)] published Thu Oct 4, 2012.

Beschreibung: Jiansheng Geng and Jian Wu In this paper, we show that one dimension derivative nonlinear Schrodinger equation admits a whitney smooth family of small amplitude, real analytic quasi-periodic solutions with two Diophantine frequencies. The proof is based on a partial Birkhoff normal form reduction and an abstract infinite dime ... [J. Math. Phys. 53, 102702 (2012)] published Thu Oct 4, 2012.

Beschreibung: Badis Ydri and Adel Bouchareb In this article we study non-commutative vector sigma model with the most general phi interaction on Moyal-Weyl spaces. We compute the 2- and 4-point functions to all orders in the large N limit and then apply the approximate Wilson renormalization group recursion formula to study the renormalized c ... [J. Math. Phys. 53, 102301 (2012)] published Thu Oct 4, 2012.

Beschreibung: Suemi Rodriguez-Romo We deal with some matters needed to construct concrete left Hopf algebras for inhomogeneous quantum groups produced as noncommutative symmetries of fermionic and bosonic creation/annihilation operators. We find a map for the bidimensional fermionic case, produced as in Manin's [Quantum Groups and No ... [J. Math. Phys. 53, 102104 (2012)] published Thu Oct 4, 2012.

Beschreibung: The climate dependence of the terrestrial carbon cycle; including parameter and structural uncertainties Biogeosciences Discussions, 9, 13439-13496, 2012 Author(s): M. J. Smith, M. C. Vanderwel, V. Lyutsarev, S. Emmott, and D. W. Purves The feedback between climate and the terrestrial carbon cycle will be a key determinant of the dynamics of the Earth System over the coming decades and centuries. However Earth System Model projections of the terrestrial carbon-balance vary widely over these timescales. This is largely due to differences in their carbon cycle models. A major goal in biogeosciences is therefore to improve understanding of the terrestrial carbon cycle to enable better constrained projections. Essential to achieving this goal will be assessing the empirical support for alternative models of component processes, identifying key uncertainties and inconsistencies, and ultimately identifying the models that are most consistent with empirical evidence. To begin meeting these requirements we data-constrained all parameters of all component processes within a global terrestrial carbon model. Our goals were to assess the climate dependencies obtained for different component processes when all parameters have been inferred from empirical data, assess whether these were consistent with current knowledge and understanding, assess the importance of different data sets and the model structure for inferring those dependencies, assess the predictive accuracy of the model, and to identify a methodology by which alternative component models could be compared within the same framework in future. Although formulated as differential equations describing carbon fluxes through plant and soil pools, the model was fitted assuming the carbon pools were in states of dynamic equilibrium (input rates equal output rates). Thus, the parameterised model is of the equilibrium terrestrial carbon cycle. All but 2 of the 12 component processes to the model were inferred to have strong climate dependencies although it was not possible to data-constrain all parameters indicating some potentially redundant details. Similar climate dependencies were obtained for most processes whether inferred individually from their corresponding data sets or using the full terrestrial carbon model and all available data sets, indicating a strong overall consistency in the information provided by different data sets under the assumed model formulation. A notable exception was plant mortality, in which qualitatively different climate dependencies were inferred depending on the model formulation and data sets used, highlighting this component as the major structural uncertainty in the model. All but two component processes predicted empirical data better than a null model in which no climate dependency was assumed. Equilibrium plant carbon was predicted especially well (explaining around 70% of the variation in the withheld evaluation data). We discuss the advantages of our approach in relation to advancing our understanding of the carbon cycle and enabling Earth System Models make better constrained projections.

Beschreibung: Nitrogen cycling in the Central Arabian Sea: a model study Biogeosciences Discussions, 9, 13581-13625, 2012 Author(s): A. Beckmann and I. Hense We present a biogeochemical model that couples the marine nitrogen and oxygen cycles and includes euphotic, aphotic, aerobic and anaerobic processes. The model is used to investigate the mechanisms affecting nitrite and nitrogen losses in the suboxic layer of the Central Arabian Sea. In an idealized two-dimensional physical environment the model is able to reproduce the observed meridional-vertical structure of suboxic zone, secondary nitrite maximum, nitrate and oxygen. Characteristic features of vertical profiles are well represented and the modelled nitrogen transformation rates are in good agreement with observed values. The model results show that the oxygen minimum zone is not vertically homogeneous, as all suboxic processes are confined to the top 100 m of this zone. Minute differences in oxygen concentration determine the thickness of the nitrite layer. The modelled average N-loss rate in the suboxic region of the Arabian Sea is about 50 mmol N m −2 yr −1 (about 30 times smaller than most previous estimates). The system response time scale is about 50 yr, much larger than usually assumed.

Beschreibung: The carbon budget of South Asia Biogeosciences Discussions, 9, 13537-13580, 2012 Author(s): P. K. Patra, J. G. Canadell, R. A. Houghton, S. L. Piao, N.-H. Oh, P. Ciais, K. R. Manjunath, A. Chhabra, T. Wang, T. Bhattacharya, P. Bousquet, J. Hartman, A. Ito, E. Mayorga, Y. Niwa, P. Raymond, V. V. S. S. Sarma, and R. Lasco The source and sinks of carbon dioxide (CO 2 ) and methane (CH 4 ) due to anthropogenic and natural biospheric activities were estimated for the South Asia region (Bangladesh, Bhutan, India, Nepal, Pakistan and Sri Lanka). Flux estimates were based on top-down methods that use inversions of atmospheric data, and bottom-up methods that use field observations, satellite data, and terrestrial ecosystem models. Based on atmospheric CO 2 inversions, the net biospheric CO 2 flux in South Asia (equivalent to the Net Biome Productivity, NBP) was a sink, estimated at −104 ± 150 Tg C yr −1 during 2007–2008. Based on the bottom-up approach, the net biospheric CO 2 flux is estimated to be −191 ± 193 Tg C yr −1 during the period of 2000–2009. This last net flux results from the following flux components: (1) the Net Ecosystem Productivity, NEP (net primary production minus heterotrophic respiration) of −220 ± 186 Tg C yr −1 (2) the annual net carbon flux from land-use change of −14 ± 50 Tg C yr −1 , which resulted from a sink of −16 Tg C yr −1 due to the establishment of tree plantations and wood harvest, and a source of 2 Tg C yr −1 due to the expansion of croplands; (3) the riverine export flux from terrestrial ecosystems to the coastal oceans of +42.9 Tg C yr −1 ; and (4) the net CO 2 emission due to biomass burning of +44.1 ± 13.7 Tg C yr −1 . Including the emissions from the combustion of fossil fuels of 444 Tg C yr −1 for the decades of 2000s, we estimate a net CO 2 land-to-atmosphere flux of 297 Tg C yr −1 . In addition to CO 2 , a fraction of the sequestered carbon in terrestrial ecosystems is released to the atmosphere as CH 4 . Based on bottom-up and top-down estimates, and chemistry-transport modeling, we estimate that 37 ± 3.7 Tg C-CH 4 yr −1 were released to atmosphere from South Asia during the 2000s. Taking all CO 2 and CH 4 fluxes together, our best estimate of the net land-to-atmosphere CO 2 -equivalent flux is a net source of 334 Tg C yr −1 for the South Asia region during the 2000s. If CH 4 emissions are weighted by radiative forcing of molecular CH 4 , the total CO 2 -equivalent flux increases to 1148 Tg C yr −1 suggesting there is great potential of reducing CH 4 emissions for stabilizing greenhouse gases concentrations.

Beschreibung: Interactions between leaf nitrogen status and longevity in relation to N cycling in three contrasting European forest canopies Biogeosciences Discussions, 9, 9759-9790, 2012 Author(s): L. Wang, A. Ibrom, J. F. J. Korhonen, K. F. Arnoud Frumau, J. Wu, M. Pihlatie, and J. K. Schjoerring Seasonal and spatial variations in foliar nitrogen (N) parameters were investigated in three European forests with different tree species, viz. beech ( Fagus sylvatica L.), Douglas fir ( Pseudotsuga menziesii , Mirb., Franco) and Scots pine ( Pinus sylvestris L.) in Denmark, The Netherlands and Finland, respectively. This was done in order to obtain information about functional acclimation, tree internal N conservation and its relevance for both ecosystem internal N cycling and foliar N exchange with the atmosphere. Leaf N pools generally showed much higher seasonal variability in beech trees than in the coniferous canopies. The concentrations of N and chlorophyll in the beech leaves were synchronized with the seasonal course of solar radiation implying close physiological acclimation, which was not observed in the coniferous needles. During phases of intensive N metabolism in the beech leaves, the NH 4 + concentration rose considerably. This was compensated for by a strong pH decrease resulting in relatively low Γ values (ratio between tissue NH 4 + and H + ). The Γ values in the coniferous were even smaller than in beech, indicating low probability of NH 3 emissions from the foliage to the atmosphere as an N conserving mechanism. The reduction in foliage N content during senescence was interpreted as N re-translocation from the senescing leaves into the rest of the trees. The N re-translocation efficiency (η r ) ranged from 37 to 70% and decreased with the time necessary for full renewal of the canopy foliage. Comparison with literature data from in total 23 tree species showed a general tendency for η r to on average be reduced by 8% per year the canopy stays longer, i.e. with each additional year it takes for canopy renewal. The boreal pine site returned the lowest amount of N via foliage litter to the soil, while the temperate Douglas fir stand which had the largest peak canopy N content and the lowestη r returned the highest amount of N to the soil. These results support the hypothesis that a high N status, e.g. as a consequence of chronically high atmospheric N inputs, increases ecosystem internal over tree-bulk-tissue internal N cycling in conifer stands. The two evergreen tree species investigated in the present study behaved very differently in all relevant parameters, i.e. needle longevity, N c and η r , showing that generalisations on tree internal vs. ecosystem internal N cycling cannot be made on the basis of the leaf habit alone.

Beschreibung: Net sea-air CO 2 flux uncertainties in the Bay of Biscay based on the choice of wind speed products and gas transfer parameterizations Biogeosciences Discussions, 9, 9993-10017, 2012 Author(s): P. Otero, X. A. Padín, M. Ruiz-Villarreal, L. M. García-García, A. F. Ríos, and F. F. Pérez The estimation of sea-air CO 2 fluxes are largely dependent on wind speed through the gas transfer velocity parameterization. In this paper, we quantify uncertainties in the estimation of the CO 2 uptake in the Bay of Biscay resulting from using different sources of wind speed such as three different global reanalysis meteorological models (NCEP/NCAR 1, NCEP/DOE 2 and ERA-Interim), one regional high-resolution forecast model (HIRLAM-AEMet) and QuikSCAT winds, in combination with some of the most widely used gas transfer velocity parameterizations. Results show that net CO 2 flux estimations during an entire seasonal cycle may differ up to 240% depending on the wind speed product and the gas exchange parameterization. The comparison of satellite and model derived winds with observations at buoys advises against the systematic overestimation of NCEP-2 and the underestimation of NCEP-1. In this region, QuikSCAT has the best performing, although ERA-Interim becomes the best choice in areas near the coastline or when the time resolution is the constraint.