Technical Note: Comparison of storage strategies of sea surface microlayer samples

The sea surface microlayer (SML) is an important biogeochemical system whose physico-chemical analysis often necessitates some degree of sample storage. However, many SML components degrade with time so the development of optimal storage protocols is paramount. We here briefly review some commonly used treatment and storage protocols. Using freshwater and saline SML samples from a river estuary, we investigated temporal changes in surfactant activity (SA) and the absorbance and fluorescence of chromophoric dissolved organic matter (CDOM) over four weeks, following selected sample treatment and storage protocols. Some variability in the effectiveness of individual protocols most likely reflects sample provenance. None of the various protocols examined performed any better than dark storage at 4 °C without pre-treatment. We therefore recommend storing samples refrigerated in the dark

Open ocean carbon monoxide photo-production

Sunlight-initiated photolysis of chromophoric dissolved organic matter (CDOM) is the dominant source of carbon monoxide (CO) in the open-ocean. A modelling study was conducted to constrain this source. Spectral solar irradiance was obtained from two models (GCSOLAR and SMARTS2). Water-column CDOM and total light absorption were modelled using spectra collected along a Meridional transect of the Atlantic ocean using a 200-cm pathlength liquid waveguide UV-visible spectrophotometer. Apparent quantum yields for the production of CO (AQYCO) from CDOM were obtained from a parameterisation describing the relationship between CDOM light absorption coefficient and AQYCO and the CDOM spectra collected. The sensitivity of predicted rates to variations in model parameters (solar irradiance, cloud cover, surface-water reflectance, CDOM and whole water light absorbance, and AQYCO was assessed. The model\u27s best estimate of open-ocean CO photoproduction was 47 +/- 7 Tg CO-C yr-1, with lower and upper limits of 38 and 84 Tg CO-C yr-1, as indicated by sensitivity analysis considering variations in AQYs, CDOM absorbance, and spectral irradiance. These results represent significant constraint of open-ocean CO photoproduction at the lower limit of previous estimates. Based on these results, and their extrapolation to total photochemical organic carbon mineralisation, we recommend a downsizing of the role of photochemistry in the open-ocean carbon cycle. (c) 2006 Elsevier Ltd. All rights reserved

Nitrous oxide and methane in the Atlantic Ocean between 50 degrees North and 52 degrees South: Latitudinal distribution and sea-to-air flux

We discuss nitrous oxide (N2O) and methane (CH4) distributions in 49 vertical profiles covering the upper 300 m of the water column along two 13,500 km transects between 50°N and 52°S during the Atlantic Meridional Transect (AMT) programme (AMT cruises 12 and 13). Vertical N2O profiles were amenable to analysis on the basis of common features coincident with Longhurst provinces. In contrast, CH4 showed no such pattern. The most striking feature of the latitudinal depth distributions was a well-defined “plume” of exceptionally high N2O concentrations coincident with very low levels of CH4, located between 23.5°N and 23.5°S; this feature reflects the upwelling of deep waters containing N2O derived from nitrification, as identified by an analysis of N2O, apparent oxygen utilization (AOU) and NO3-, and presumably depleted in CH4 by bacterial oxidation. Sea-to-air emissions fluxes for a region equivalent to 42% of the Atlantic Ocean surface area were in the range 0.40–0.68 Tg N2O yr-1 and 0.81–1.43 Tg CH4 yr-1. Based on contemporary estimates of the global ocean source strengths of atmospheric N2O and CH4, the Atlantic Ocean could account for 6–15% and 4–13%, respectively, of these source totals. Given that the Atlantic Ocean accounts for around 20% of the global ocean surface, on unit area basis it appears that the Atlantic may be a slightly weaker source of atmospheric N2O than other ocean regions but it could make a somewhat larger contribution to marine-derived atmospheric CH4 than previously thought

A Roadmap for Interdisciplinary Research on the Internet of Things

In mid-2011, the Technology Strategy Board started an integrated programme of work focused on the Internet of Things (IoT), which included strategic investment and the establishment of a Special Interest Group aimed at building and engaging a UK community of innovators and researchers in the IoT. As the portfolio of activities with businesses, academics and other stakeholders progressed, it became apparent to us that the community had a keen interest in taking a more concerted and deeper look at the fundamental research issues in the IoT and that a more interdisciplinary approach was needed.Responding to this level of interest, the Technology Strategy Board joined forces with the Arts and Humanities Research Council, the Economic and Social Research Council, the Engineering and Physical Sciences Research Council and the Research Councils UK Digital Economy Programme and agreed to collaborate on an interdisciplinary R&D roadmapping activity, arguably the first of its kind in the UK. The activity, led by Professors Rahim Tafazolli, Hamid Aghvami, Rachel Cooper, William Dutton and Dr Colin Upstill brought together insight from a wide group of leaders and culminated in a two-day ‘meeting of minds’ in Loughborough on 11 and 12 July 2012. This report summarises the outcomes of the activity and makes important wide-ranging recommendations

Water Quality, nutrients and the European Union’s Water Framework Directive in a lowland agricultural region: Suffolk, south-east England.

The water quality of 13 rivers in the lowland, agricultural county of Suffolk is investigated using routine monitoring data for the period 1981 to 2006 collected by the Environment Agency of England and Wales (EA), and its predecessors, with particular emphasis on phosphorus (as total reactive phosphorus, TRP) and total (dissolved and particulate) oxidised nitrogen (TOxN – predominantly nitrate NO3). Major ion and flow data are used to outline fundamental hydrochemical characteristics related to the groundwater provenance of base-flow waters. Relative load contributions from point and diffuse sources are approximated using Load Apportionment Modelling for both TRP and TOxN where concurrent flow and concentration data are available. Analyses indicate a mixture of point and diffuse sources of TRP, with the former being dominant during low flow periods, while for TOxN diffuse sources dominate. Out of 59 sites considered, 53 (90%) were found to have annual average TRP concentrations greater than 0.05 mg P l-1, and 36 (61%) had average concentrations over 0.120 mg P l-1, the upper thresholds for ‘High’ and ‘Good’ ecological status, respectively. Correspondingly, for TOxN, most of the rivers are already within 70% of the 11.3 mg N l-1 threshold, with two rivers (Wang and Ore) being consistently greater than this. It is suggested that the major challenge is to characterise and control point-source TRP inputs which, being predominant during the late spring and summer low-flow period, coincide with the peak of primary biological production, thus presenting the major challenge to achieving ‘good’ ecological status under the Water Framework Directive. Results show that considerable effort is still required to ensure appropriate management and develop tools for decision-support

Nitrous oxide emissions from the Arabian Sea: A synthesis

We computed high-resolution (1º latitude x 1º longitude) seasonal and annual nitrous oxide (N2O) concentration fields for the Arabian Sea surface layer using a database containing more than 2400 values measured between December 1977 and July 1997. N2O concentrations are highest during the southwest (SW) monsoon along the southern Indian continental shelf. Annual emissions range from 0.33 to 0.70 Tg N2O and are dominated by fluxes from coastal regions during the SW and northeast monsoons. Our revised estimate for the annual N2O flux from the Arabian Sea is much more tightly constrained than the previous consensus derived using averaged in-situ data from a smaller number of studies. However, the tendency to focus on measurements in locally restricted features in combination with insufficient seasonal data coverage leads to considerable uncertainties of the concentration fields and thus in the flux estimates, especially in the coastal zones of the northern and eastern Arabian Sea. The overall mean relative error of the annual N2O emissions from the Arabian Sea was estimated to be at least 65%