Temperature and Moisture Influence on Compression-Recovery Behavior of Wood

The primary limitation of non-veneer wood composites for applications in moist environments is dimensional instability. Thickness instabilities from moisture absorption primarily result from damaged cell structures that recover upon absorption of moisture. Previous research has shown that manipulating the pressing parameters involved in the manufacture of non-veneer wood composites (i.e., temperature and moisture) can lead to a more dimensionally stable product. However, the precise phenomena controlling these changes are not fully defined. To understand development of pressing-induced damage, the large strain, compression-recovery behavior of wood and polyurethane (PUR) foam (i.e., as a model system) was studied at a variety of compression temperatures spanning the glassy to rubber transition. The behavior is then related to polymer phase transitions to discern the role of viscoelastic behavior in damage evolution. The elastic modulus (E) and yield stress (σy) were used to characterize the elastic region of compression, whereas fractional recovery (R) and dissipated energy (ΔE) represented the inelastic component. The PUR foam displayed a distinct glassy plateau region dominated by E, σy, and ΔE as well as low R. Wood with 22 and 12% MC behaved similarly to the elastomeric PUR foam; however, limits on environmental control prevented testing in the rubbery regime for the 12% MC samples. The E and σy also decreased with increasing compression temperature for ovendried yellow-poplar. However, in contrast to yellow-poplar with either 12 or 22% MC, an increase in ΔE was accompanied by a decrease in R with increasing compression temperature of the oven-dried yellow-poplar. An apparent change in mechanism occurs when compressing wood at high temperatures without moisture present. This change was attributed to kinetic effects such as thermal degradation or crosslinking reactions

Spatial assessment of intertidal seagrass meadows using optical imaging systems and a lightweight drone

Seagrass ecosystems are highly sensitive to environmental change. They are also in global decline and under threat from a variety of anthropogenic factors. There is now an urgency to establish robust monitoring methodologies so that changes in seagrass abundance and distribution in these sensitive coastal environments can be understood. Typical monitoring approaches have included remote sensing from satellites and airborne platforms, ground based ecological surveys and snorkel/scuba surveys. These techniques can suffer from temporal and spatial inconsistency, or are very localised making it hard to assess seagrass meadows in a structured manner. Here we present a novel technique using a lightweight (sub 7 kg) drone and consumer grade cameras to produce very high spatial resolution (∼4 mm pixel−1) mosaics of two intertidal sites in Wales, UK. We present a full data collection methodology followed by a selection of classification techniques to produce coverage estimates at each site. We trialled three classification approaches of varying complexity to investigate and illustrate the differing performance and capabilities of each. Our results show that unsupervised classifications perform better than object-based methods in classifying seagrass cover. We also found that the more sparsely vegetated of the two meadows studied was more accurately classified - it had lower root mean squared deviation (RMSD) between observed and classified coverage (9–9.5%) compared to a more densely vegetated meadow (RMSD 16–22%). Furthermore, we examine the potential to detect other biotic features, finding that lugworm mounds can be detected visually at coarser resolutions such as 43 mm pixel−1, whereas smaller features such as cockle shells within seagrass require finer grained data (<17 mm pixel−1)

Comentarios a la ponencia "Igualdades, desigualdades y derechos", presentada por Mirta Lobato

Teniendo en cuenta -como advierte Mirta Lobato a los comentaristas- que cuando habla de desigualdades en su ponencia se refiere a que "el trabajo es el eje articulador de estas reflexiones", y sin dejar de reconocer la importancia que cabe a los otros temas y sujetos sobre los que tan bien desarrolla su exposición, quiero centrarme en un grupo que estoy estudiando desde hace unos años, como es el de los inmigrantes limítrofes a la Argentina de fin de siglo XX e inicios del XXI. Para ello, voy a analizar brevemente -como así lo exigen las reglas del comentario- a estos sujetos sociales, a quienes, como también ella afirma, ya los habríamos de encontrar censalmente a inicios del siglo pasado, aunque su visibilidad fuera menor porque aún no habían arribado a Buenos Aires; es decir, al escenario donde "las cosas suceden".Fil: Benencia, Roberto Rodolfo. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Community Review of Southern Ocean Satellite Data Needs

This review represents the Southern Ocean community’s satellite data needs for the coming decade. Developed through widespread engagement, and incorporating perspectives from a range of stakeholders (both research and operational), it is designed as an important community-driven strategy paper that provides the rationale and information required for future planning and investment. The Southern Ocean is vast but globally connected, and the communities that require satellite-derived data in the region are diverse. This review includes many observable variables, including sea-ice properties, sea-surface temperature, sea-surface height, atmospheric parameters, marine biology (both micro and macro) and related activities, terrestrial cryospheric connections, sea-surface salinity, and a discussion of coincident and in situ data collection. Recommendations include commitment to data continuity, increase in particular capabilities (sensor types, spatial, temporal), improvements in dissemination of data/products/uncertainties, and innovation in calibration/validation capabilities. Full recommendations are detailed by variable as well as summarized. This review provides a starting point for scientists to understand more about Southern Ocean processes and their global roles, for funders to understand the desires of the community, for commercial operators to safely conduct their activities in the Southern Ocean, and for space agencies to gain greater impact from Southern Ocean-related acquisitions and missions.The authors acknowledge the Climate at the Cryosphere program and the Southern Ocean Observing System for initiating this community effort, WCRP, SCAR, and SCOR for endorsing the effort, and CliC, SOOS, and SCAR for supporting authors’ travel for collaboration on the review. Jamie Shutler’s time on this review was funded by the European Space Agency project OceanFlux Greenhouse Gases Evolution (Contract number 4000112091/14/I-LG)

Revised estimates of ocean-atmosphere CO2 flux are consistent with ocean carbon inventory

This is the final version. Available from the publisher via the DOI in this record.The ocean is a sink for ~25% of the atmospheric CO2 emitted by human activities, an amount in excess of 2 petagrams of carbon per year (PgC yr−1 ). Time-resolved estimates of global ocean-atmosphere CO2 flux provide an important constraint on the global carbon budget. However, previous estimates of this flux, derived from surface ocean CO2 concentrations, have not corrected the data for temperature gradients between the surface and sampling at a few meters depth, or for the effect of the cool ocean surface skin. Here we calculate a time history of ocean-atmosphere CO2 fluxes from 1992 to 2018, corrected for these effects. These increase the calculated net flux into the oceans by 0.8–0.9 PgC yr−1 , at times doubling uncorrected values. We estimate uncertainties using multiple interpolation methods, finding convergent results for fluxes globally after 2000, or over the Northern Hemisphere throughout the period. Our corrections reconcile surface uptake with independent estimates of the increase in ocean CO2 inventory, and suggest most ocean models underestimate uptake.European Space AgencyEuropean CommissionBONUS Secretariat (EEIG

On the Potential of Surfers to Monitor Environmental Indicators in the Coastal Zone

The social and economic benefits of the coastal zone make it one of the most treasured environments on our planet. Yet it is vulnerable to increasing anthropogenic pressure and climate change. Coastal management aims to mitigate these pressures while augmenting the socio-economic benefits the coastal region has to offer. However, coastal management is challenged by inadequate sampling of key environmental indicators, partly due to issues relating to cost of data collection. Here, we investigate the use of recreational surfers as platforms to improve sampling coverage of environmental indicators in the coastal zone. We equipped a recreational surfer, based in the south west United Kingdom (UK), with a temperature sensor and Global Positioning System (GPS) device that they used when surfing for a period of one year (85 surfing sessions). The temperature sensor was used to derive estimates of sea-surface temperature (SST), an important environmental indicator, and the GPS device used to provide sample location and to extract information on surfer performance. SST data acquired by the surfer were compared with data from an oceanographic station in the south west UK and with satellite observations. Our results demonstrate: (i) high-quality SST data can be acquired by surfers using low cost sensors; and (ii) GPS data can provide information on surfing performance that may help motivate data collection by surfers. Using recent estimates of the UK surfing population, and frequency of surfer participation, we speculate around 40 million measurements on environmental indicators per year could be acquired at the UK coastline by surfers. This quantity of data is likely to enhance coastal monitoring and aid UK coastal management. Considering surfing is a world-wide sport, our results have global implications and the approach could be expanded to other popular marine recreational activities for coastal monitoring of environmental indicators

A reconciliation of empirical and mechanistic models of the air-sea gas transfer velocity

Models of the air-sea transfer velocity of gases may be either empirical or mechanistic. Extrapolations of empirical models to an unmeasured gas or to another water temperature can be erroneous if the basis of that extrapolation is flawed. This issue is readily demonstrated for the most well-known empirical gas transfer velocity models where the influence of bubble-mediated transfer, which can vary between gases, is not explicitly accounted for. Mechanistic models are hindered by an incomplete knowledge of the mechanisms of air-sea gas transfer. We describe a hybrid model that incorporates a simple mechanistic view—strictly enforcing a distinction between direct and bubble-mediated transfer—but also uses parameterizations based on data from eddy flux measurements of dimethyl sulphide (DMS) to calibrate the model together with dual tracer results to evaluate the model. This model underpins simple algorithms that can be easily applied within schemes to calculate local, regional, or global air-sea fluxes of gases

Sensitivity of Modeled CO2 Air–Sea Flux in a Coastal Environment to Surface Temperature Gradients, Surfactants, and Satellite Data Assimilation

This work evaluates the sensitivity of CO2 air–sea gas exchange in a coastal site to four different model system configurations of the 1D coupled hydrodynamic–ecosystem model GOTM–ERSEM, towards identifying critical dynamics of relevance when specifically addressing quantification of air–sea CO2 exchange. The European Sea Regional Ecosystem Model (ERSEM) is a biomass and functional group-based biogeochemical model that includes a comprehensive carbonate system and explicitly simulates the production of dissolved organic carbon, dissolved inorganic carbon and organic matter. The model was implemented at the coastal station L4 (4 nm south of Plymouth, 50°15.00’N, 4°13.02’W, depth of 51 m). The model performance was evaluated using more than 1500 hydrological and biochemical observations routinely collected at L4 through the Western Coastal Observatory activities of 2008—2009. In addition to a reference simulation (A), we ran three distinct experiments to investigate the sensitivity of the carbonate system and modeled air–sea fluxes to (B) the sea-surface temperature (SST) diurnal cycle and thus also the near-surface verticalgradients,(C)biologicalsuppressionofgasexchangeand(D)dataassimilationusingsatellite Earth observation data. The reference simulation captures well the physical environment (simulated SST has a correlation with observations equal to 0.94 with a p > 0.95). Overall, the model captures the seasonal signal in most biogeochemical variables including the air–sea flux of CO2 and primary production and can capture some of the intra-seasonal variability and short-lived blooms. The model correctlyreproducestheseasonalityofnutrients(correlation>0.80forsilicate,nitrateandphosphate), surface chlorophyll-a (correlation > 0.43) and total biomass (correlation > 0.7) in a two year run for 2008–2009. The model simulates well the concentration of DIC, pH and in-water partial pressure of CO2 (pCO2) with correlations between 0.4–0.5. The model result suggest that L4 is a weak net source of CO2 (0.3–1.8 molCm−2 year−1). The results of the three sensitivity experiments indicate that both resolving the temperature profile near the surface and assimilation of surface chlorophyll-a significantlyimpacttheskillofsimulatingthebiogeochemistryatL4andallofthecarbonatechemistry related variables. These results indicate that our forecasting ability of CO2 air–sea flux in shelf seas environments and their impact in climate modeling should consider both model refinements as means of reducing uncertainties and errors in any future climate projections

Air–sea CO2 exchange in the Baltic Sea - A sensitivity analysis of the gas transfer velocity

This is the final version. Available on open access from Elsevier via the DOI in this recordAir–sea gas fluxes are commonly estimated using wind-based parametrizations of the gas transfer velocity. However, neglecting gas exchange forcing mechanisms – other than wind speed – may lead to large uncertainties in the flux estimates and the carbon budgets, in particular, in heterogeneous environments such as marginal seas and coastal areas. In this study we investigated the impact of including relevant processes to the air–sea CO flux parametrization for the Baltic Sea. We used six parametrizations of the gas transfer velocity to evaluate the effect of precipitation, water-side convection, and surfactants on the net CO flux at regional and sub-regional scale. The differences both in the mean CO fluxes and the integrated net fluxes were small between the different cases. However, the implications on the seasonal variability were shown to be significant. The inter-annual and spatial variability were also found to be associated with the forcing mechanisms evaluated in the study. In addition to wind, water-side convection was the most relevant parameter controlling the air–sea gas exchange at seasonal and inter-annual scales. The effect of precipitation and surfactants seemed negligible in terms of the inter-annual variability. The effect of water-side convection and surfactants resulted in a reduction of the downward fluxes, while precipitation was the only parameter that resulted in an enhancement of the net uptake in the Baltic Sea.BONUS Secretariat (EEIG

Carbon on the Northwest European Shelf: Contemporary Budget and Future Influences

A carbon budget for the northwest European continental shelf seas (NWES) was synthesized using available estimates for coastal, pelagic and benthic carbon stocks and flows. Key uncertainties were identified and the effect of future impacts on the carbon budget were assessed. The water of the shelf seas contains between 210 and 230 Tmol of carbon and absorbs between 1.3 and 3.3 Tmol from the atmosphere annually. Off-shelf transport and burial in the sediments account for 60–100 and 0–40% of carbon outputs from the NWES, respectively. Both of these fluxes remain poorly constrained by observations and resolving their magnitudes and relative importance is a key research priority. Pelagic and benthic carbon stocks are dominated by inorganic carbon. Shelf sediments contain the largest stock of carbon, with between 520 and 1600 Tmol stored in the top 0.1 m of the sea bed. Coastal habitats such as salt marshes and mud flats contain large amounts of carbon per unit area but their total carbon stocks are small compared to pelagic and benthic stocks due to their smaller spatial extent. The large pelagic stock of carbon will continue to increase due to the rising concentration of atmospheric CO2, with associated pH decrease. Pelagic carbon stocks and flows are also likely to be significantly affected by increasing acidity and temperature, and circulation changes but the net impact is uncertain. Benthic carbon stocks will be affected by increasing temperature and acidity, and decreasing oxygen concentrations, although the net impact of these interrelated changes on carbon stocks is uncertain and a major knowledge gap. The impact of bottom trawling on benthic carbon stocks is unique amongst the impacts we consider in that it is widespread and also directly manageable, although its net effect on the carbon budget is uncertain. Coastal habitats are vulnerable to sea level rise and are strongly impacted by management decisions. Local, national and regional actions have the potential to protect or enhance carbon storage, but ultimately global governance, via controls on emissions, has the greatest potential to influence the long-term fate of carbon stocks in the northwestern European continental shelf