Organic Flux Research Articles

Response of Recent Benthic Foraminiferal Assemblages to Contrasting Environments in Baffin Bay and the Northern Labrador Sea, Northwest Atlantic

Modern deep-water benthic foraminiferal assemblages in Baffin Bay and the northern Labrador Sea, Western North Atlantic, were sampled from box cores and analyzed to determine assemblage composition. The two marine basins are separated by the shallow waters of Davis Strait. Assemblages of Baffin Bay contained only agglutinated foraminifera, whereas samples from the Labrador Sea contained both calcareous and agglutinated species, which resulted in significantly higher species richness. The absence of benthic calcareous taxa in Baffin Bay is attributed to cold, saline, CO2-rich bottom waters related to the Baffin Bay Bottom Water and the Baffin Bay Atlantic Water. Modern foraminiferal assemblage distribution supports the model of increased organic flux under seasonal open-water conditions that feed a rich agglutinated assemblage, but lead to oxidation of organic matter and increased carbonate dissolution. Deep-water sediments contain ice-rafted coarse-grained components and biogenic elements such as sponge spicules that are heavily used by numerous agglutinated species for test construction. Robust, tubular suspension feeders occupy regions under the influence of bottom currents that deliver nutrients. Although disturbances of the sediment-water interface cannot be excluded with sampled box cores, small-scale patchiness can be confirmed by varying abundances of infaunal taxa. Absolute counts of specimens in subsamples vary signif­icantly, whereas species evenness among subsamples is less variable. These findings call for caution when interpreting lateral faunal changes on the basis of small core samples.

Quantification of the volatility of secondary organic compounds in ultrafine particles during nucleation events

Abstract. Condensation of secondary organic compounds onto ultrafine aerosols is important for growing these particles to sizes where they can act as cloud condensation nuclei. The organic flux to ultrafine particles depends strongly on the volatility of the condensing compounds. This paper presents quantitative estimates of the volatility of secondary organic aerosol (SOA) in freshly nucleated particles. We examine 13 nucleation/growth events in two remote continental locations, Hyytiälä, Finland and Egbert, ON, Canada. Two independent methods are used to quantify the volatility of the growing nucleation mode: (1) modelling of the growing nucleation mode to determine which volatilities allow the model to reproduce observed growth, and (2) modelling of the evaporation of heated aerosols in a Volatility Differential Mobility Particle Sizer to determine which volatilities allow the model to reproduce the observed evaporation. We find that the average saturation vapor concentration (C*) in the freshly nucleated particles (once Dp > 3 nm) is likely less than 10−3–10−2 μg m−3 (this corresponds to 3 × 106−3 × 107 molecules cm−3 and a saturation vapor pressure of 10−8–10−7 Pa). This maximum volatility depends somewhat on other uncertain factors that affect the size-dependent condensation of secondary organic compounds such as the surface tension, mass accommodation coefficient and the volatility of the pre-existing aerosols. However, our tests suggest that under no reasonable assumptions can the SOA in the ultrafine particles contain a majority of compounds with C* > 10−2 μg m−3. We demonstrate that the growth could be driven by either gas-phase or particle-phase chemistry but cannot conclude which is responsible for the low-volatility SOA.

Diverse patterns of ocean export productivity change across the Cretaceous‐Paleogene boundary: New insights from biogenic barium

One of the best‐studied aspects of the K‐Pg mass extinction is the decline and subsequent recovery of open ocean export productivity (e.g., the flux of organic matter from the surface to deep ocean). Some export proxies, including surface‐to‐deep water δ13C gradients and carbonate sedimentation rates, indicate a global decline in export productivity triggered by the extinction. In contrast, benthic foraminiferal and other geochemical productivity proxies suggest spatially and temporally heterogeneous K‐Pg boundary effects. Here we address these conflicting export productivity patterns using new and compiled measurements of biogenic barium. Unlike a previous synthesis, we find that the boundary effect on export productivity and the timing of recovery varied considerably between different oceanic sites. The northeast and southwest Atlantic, Southern Ocean, and Indian Ocean records saw export production plummet and remain depressed for 350 thousand to 2 million years. Biogenic barium and other proxies in the central Pacific and some upwelling or neritic Atlantic sites indicate the opposite, with proxies recording either no change or increased export production in the early Paleocene. Our results suggest that widespread declines in surface‐to‐deep ocean δ13C do not record a global decrease in export productivity. Rather, independent proxies, including barium and other geochemical proxies, and benthic community structure, indicate that some regions were characterized by maintained or rapidly recovered organic flux from the surface ocean to the deep seafloor, while other regions had profound reductions in export productivity that persisted long into the Paleocene.

Characterisation of Ottnangian (middle Burdigalian) palaeoenvironments in the North Alpine Foreland Basin using benthic foraminifera—A review of the Upper Marine Molasse of southern Germany

Abstract Considerable facies changes and varying foraminiferal assemblages have been described from the lower Miocene sediments of the Upper Marine Molasse in the North Alpine Foreland Basin of southern Germany, and have resulted in the distinction of a “Western Molasse” and “Eastern Molasse”. However, the causes and processes leading to these local differences have largely remained unexplored to date. The aim of this study is to explore possible explanations in order to better understand the palaeogeographic, stratigraphic and environmental setting. The study focuses on the Ottnangian (middle Burdigalian) segment of the Upper Marine Molasse in southern Germany, and includes a review of previously published data, together with new data from the borehole Stockhausen which is located between the areas of the Eastern and Western Molasse. Methods include quantitative analysis of benthic foraminiferal assemblages, qualitative studies of planktonic foraminifera and calcareous nannoplankton, as well as palaeoenvironmental considerations based on the actualistic approach. The results of these studies demonstrate that the lower and middle Ottnangian Upper Marine Molasse include a single transgressive–regressive sedimentary cycle with gradual changes of foraminiferal assemblages in the Eastern Molasse. On the other hand, two sedimentation cycles are recognizable in the Western Molasse and in the borehole Stockhausen where the lower and middle Ottnangian sediments are separated from one another by an unconformity and display an abrupt change in lithofacies and foraminiferal content. The benthic foraminiferal assemblages from the area of the Western Molasse are indicative of a rather shallow sea, but indicative of a much deeper facies in the basin area of the Eastern Molasse. It can therefore be concluded that the shallow sea to the west was more sensitive to minor changes in sea level than the area of the Eastern Molasse, either because of global sea level variation or as a result of regional tectonics. This means that the occurrence of two sedimentary cycles in the Western Molasse, and absence of the second cycle in the Eastern Molasse, may be the result of shallower water depths and a lower subsidence rate in the area of the Western Molasse. Another interesting result from our studies relates to the sea-level highstand and maximum extension of the Upper Marine Molasse Sea that, based on our studies, has occurred during the early Ottnangian, rather than during the middle Ottnangian as suggested previously. During this highstand, the area of the Eastern Molasse displays a differentiation into a deep neritic basin facies characterised by high organic flux and moderate oxygen depletion at times, and a marginal marine facies with well oxygenated environments. The latter facies remained poorly understood until recently. The entire region of the South German Molasse Basin was affected by a regression during the middle Ottnangian. This phase is characterised by unstable environmental conditions in the Eastern Molasse, i.e. salinity fluctuations and temporarily strong oxygen depletion of bottom waters. In the Western Molasse, life conditions became even worse and, as a result, a drastic decline in marine life is observable.

Seasonal variability of meio- and macrobenthic standing stocks and diversity in an Arctic fjord (Adventfjorden, Spitsbergen)

Strong environmental seasonality is a basic feature of the Arctic system, still there are few published records of the seasonal variability of the Arctic marine biota. This study examined the year-round seasonal changes of soft bottom macro- and meiobenthic standing stocks and diversity on a station located in an Arctic fjord (Adventfjorden, Spitsbergen). The seasonality observed in benthic biota was related to the pelagic processes, primarily the seasonal fluxes of organic and inorganic particles. The highest abundance, biomass and richness of benthic fauna occurred in the spring after the phytoplankton bloom. During the summer, when a high load of glacial mineral material was transported to the fiord, the number of both meio- and macrobenthic individuals decreased remarkably. The strong inorganic sedimentation in summer was accompanied by a decline in macrobenthic species richness, but had no effects on evenness. Redundancy analysis (RDA) pointed to granulometric composition of sediments (depended on mineral sedimentation) and organic fluxes as factors best related to meio- and macrobenthic taxonomic composition, but no clear seasonal trend could be observed on the nMDS plots based on meiobenthic higher taxa or macrobenthic species abundances in the samples. This study addresses the possible effects of changes in the winter ice cover on the fjordic benthic systems because it was performed in a year with no ice cover on the fjord.

How Silver Powder Metallurgy Affects the Physical Properties of Low Temperature Firing Silver Conductor

With the implementation of RoHS (the Restriction of Hazardous Substance) Directive banning the use of Lead, Cadmium, Mercury and Hexavalent Chromium, hybrid microelectronic manufacturers are globally embracing the lead free movement. These manufacturers must not only understand the implications of their material choice but must be aware of the interaction between lead free solder alloys and their RoHS compliant thick film materials. It is commonly known that lead free solder alloys process at much higher reflow temperatures than lead containing solder which can directly impact the fired film leach resistance and the loss of adhesion. There are also other concerns; lead free solders alloys generally require a different organic flux system to promote wetting and reflow, but this change may cause a fired film conductor to leach more easily than the flux used in the lead containing solders. The use of lead free solders such as SAC305, SAC405 or 95/5 on a low firing (550–570 °C) pure silver conductor has the tendency of leaching the fired film more readily than conductors containing small amounts of palladium or platinum. Many of these situations provide new challenges for the hybrid circuit manufacturer. There is little information available regarding the effects of the lead free solders on low firing silver thick film conductors. This paper discusses the results of a newly developed Pb and Cd free silver thick film conductor paste with a modified silver powder metallurgy to improve the leach resistance, solder acceptance and adhesion using lead free solder. In addition, the pure silver conductor was fired on top of a low temperature dielectric paste. This conductor was evaluated by comparing lead free solder alloys to traditional tin-lead-silver solder alloys. This study included evaluations based on SEM photos, solderability, leach resistance, and initial and long term adhesions. Results are published describing the difference in behavior between the different solder alloys in conjunction with the different silver powder metallurgy.

Interannual variability in vertical export in the Ross Sea: Magnitude, composition, and environmental correlates

The vertical flux of particulate matter from the surface of the Ross Sea, Antarctica, has been suggested as being large, with substantial seasonal and spatial variations. We conducted a study in which vertical flux was quantified using sediment traps deployed at 200 m and compared to estimates calculated from one-dimensional budgets of nutrients (nitrogen and silicon). Estimates of flux were collected at two locations in the southern Ross Sea from late December to early February during four years: 2001–2002, 2003–2004, 2004–2005, and 2005–2006. Phytoplankton biomass and vertical flux varied substantially seasonally and spatially between the two sites, and among years. The greatest flux was observed in 2001–2002, with a short-term maximum organic carbon flux of 3.13 mmol m −2 d −1, and the summer mean organic carbon flux equal to 0.93 mmol m −2 d −1. In contrast, the mean carbon flux at the same site in 2003–2004 was over an order of magnitude less, averaging 0.19 mmol m −2 d −1, despite the fact that productivity in that year was substantially greater. In 2005–206 the contribution of fecal pellets to flux was smallest among all years, and the pellet contribution ranged from <1 to more than 50% of organic flux. As the moorings also had surface layer fluorometers, the relationship between surface biomass and sediment trap flux was compared. Temporal lags between surface fluorescence and flux at 200 m maxima in 2003–2004 and 2004–2005 ranged from two to six days; however, in 2005–2006 the temporal offset between biomass and flux was much longer, ranging from 11 to 27 days, suggesting that fecal pellet production appeared to increase the coupling between flux and surface production. Estimates of export from the upper 200 m based on one-dimensional nutrient budgets were greater than those recorded by the sediment traps. Nutrient budgets also indicated that siliceous production averaged ca. 40% of the total annual production. The variations observed in the flux of biogenic matter to depth in the Ross Sea are large, appear to reflect different forcing among years, and at present are not adequately understood. However, such variability needs to be both understood and represented in biogeochemical models to accurately assess and predict the effects of climate change on biogeochemical cycles.

234Th-derived particulate organic carbon export flux in the western Arctic Ocean

To evaluate the particle dynamics and estimate the POC (particulate organic carbon) export flux from the euphotic zone in the western Arctic Ocean, 234Th-238U disequilibrium was applied during the second Chinese National Arctic Research Expedition (July 15–September 26, 2003). The POC export fluxes are estimated from the measured profiles of the 234Th/238U activity ratios and the POC/PTh ratios. The average residence times of the particulate and dissolved 234Th in the euphotic zone are 33 d and 121 d, and their average export fluxes are 480 dpm/m2d and 760 dpm/m2d, respectively. The scavenging and removal processes of particle reactive elements are active in the upper layer of the Chukchi Sea. The average residence time of 234Th increases from shelf to basin, while the export fluxes of 234Th decrease. The estimated POC export fluxes from the euphotic zone vary from 2.1 to 20.3 mmol/m2d, indicating that the western Arctic Ocean is an important carbon sink in summer due to efficient biological pump.

Modeling the dynamics and export of dissolved organic matter in the Northeastern U.S. continental shelf

Continental shelves are believed to play a major role in carbon cycling due to their high productivity. To improve our understanding of carbon dynamics on continental margins, a dissolved organic matter (DOM) model was developed and imbedded within an existing coupled ocean circulation-biogeochemical model of the U.S. East coast. A model simulation with the DOM module was compared with the reference model (without the DOM module) to illustrate the role of DOM dynamics in coastal ocean biogeochemical cycling. Model results reveal that the progressive release of dissolved organic nitrogen (DON) in the ocean’s upper layer during summer increases the regenerated primary production by 30–300%, which, in turn, enhances the dissolved organic carbon (DOC) production mainly from phytoplankton exudation in the upper layer and solubilization of particulate organic matter (POM) deeper in the water column. This analysis suggests that DOM is a necessary component for representing ecosystem functioning and organic fluxes in models because DOM (1) is a major organic pool directly related to primary production, (2) decouples partially the carbon and nitrogen cycles (through carbon excess uptake, POM solubilization and DOM mineralization) and (3) is intimately linked to the residence time of water masses for its distribution and export. The seasonally produced DOC on the shelf can be exported to the open ocean by horizontal transport at comparable rates (1–2 mol C m −2 yr −1) to particulate organic carbon burial in the southern U.S. Mid-Atlantic Bight (MAB).

Denitrification, N-fixation and nitrogen and phosphorus fluxes in different benthic habitats and their contribution to the nitrogen and phosphorus budgets of a shallow oligotrophic sub-tropical coastal system (southern Moreton Bay, Australia)

Denitrification, N-fixation, and dissolved inorganic and organic fluxes of nitrogen (N) and phosphorus (P) were measured in each of the major benthic habitat types of a shallow oligotrophic sub-tropical coastal system, and N and P budgets were constructed to quantify the importance of each habitat to N and P cycling in the whole ecosystem. The productivity/respiration (p/r) ratio (trophic status) of the habitats was an important control on the rates, direction (uptake, efflux) and composition (dissolved inorganic N (DIN), dissolved organic N (DON), N2) of N fluxes across the sediment–water interface, with an efflux below p/r = 1.5 and an uptake above p/r = 1.5. The Zostera Seagrass Community was the most important habitat for N loss via net N2 effluxes (denitrification; 48%). Denitrification rates in seagrass were higher than those previously measured in temperate regions, most likely due to greater availability of NH4 + for coupled nitrification–denitrification. Yabby Shoals (sub-tidal shoals inhabited by burrowing shrimp, Trypaea australiensis) accounted for the second largest loss of N via denitrification, the largest recycling of DIN and dissolved inorganic P (DIP; statistically significant only during the dark in summer) across the sediment–water interface and the second largest uptake of DON (statistically significant only in summer). This study highlighted that shallow subtropical coastal systems have a complex mosaic of benthic habitats and that some less ‘iconic’ habitats (i.e. non-seagrass) also make an important functional contribution that controls the flow of N and P through the whole ecosystem.

Deep-sea faunal provinces and their inferred environments in the Indian Ocean based on distribution of Recent benthic foraminifera

Multivariate analysis was performed on percentages of 46 species of unstained deep-sea benthic foraminifera from 131 core-top to near-core-top samples (322–5013 m) from across the Indian Ocean. Faunal data are combined with GEOSECS geochemical data to investigate any relationship between benthic foraminifera (assemblages and species) and deep-sea properties. In general, benthic foraminifera show a good correlation to surface productivity, organic carbon flux to the sea floor, deep-sea oxygenation and, to a lesser extent, to bottom temperature, without correlation with the water depths. The foraminiferal census data combined with geochemical data has enabled the division of the Indian Ocean into two faunal provinces. Province A occupies the northwestern Indian Ocean (Arabian Sea region) where surface primary production has a major maximum during the summer monsoon season and a secondary maximum during winter monsoon season that leads to high organic flux to the seafloor, making the deep-sea one of the most oxygen-deficient regions in the world ocean, with a pronounced oxygen minimum zone (OMZ). This province is dominated by benthic foraminifera characteristic of low oxygen and high organic food flux including Uvigerina peregrina, Robulus nicobarensis, Bolivinita pseudopunctata, Bolivinita sp., Bulimina aculeata, Bulimina alazanensis, Ehrenbergina carinata and Cassidulina carinata. Province B covers southern, southeastern and eastern parts of the Indian Ocean and is dominated by Nuttallides umbonifera, Epistominella exigua, Globocassidulina subglobosa, Uvigerina proboscidea, Cibicides wuellerstorfi, Cassidulina laevigata, Pullenia bulloides, Pullenia osloensis, Pyrgo murrhina, Oridorsalis umbonatus, Gyroidinoides (= Gyroidina) soldanii and Gyroidinoides cf. gemma suggesting well-oxygenated, cold deep water with low (oligotrophic) and pulsed food supply.

Live benthic foraminiferal faunas along a bathymetrical transect (140–4800 m) in the Bay of Biscay (NE Atlantic)

In a 10-stations bathymetrical transect in the Bay of Biscay, we observed important changes in the density, composition and microhabitats of live foraminiferal faunas from the outer continental shelf to the abyssal plain. Four zones are recognised: (1) at the upper continental shelf (140 m water depth), foraminiferal densities are very high and the superficial sediment is occupied by Bolivina subaenariensis and Valvulineria bradyana. Globobulimina spp., Chilostomella oolina and Nonion fabum dominate the infaunal niches, which are positioned close to the sediment–water interface due to a strong compaction of the vertical succession of redox zones. (2) At the upper continental slope stations (300–1000 m), foraminiferal densities are high and the superficial sediments are dominated by Uvigerina mediterranea/peregrina. Deeper in the sediment, intermediate infaunal niches are occupied by Melonis barleeanus. Due to a deeper oxygen penetration, the deep infaunal taxa Globobulimina spp . and C. oolina live at a considerable depth in the sediment. (3) At the mid and lower slope stations (1000–2000 m) in the superficial sediment Cibicidoides kullenbergi and Hoeglundina elegans progressively replace U. mediterranea. U. peregrina is still a dominant taxon, reflecting its preference for a somewhat intermediate organic flux level. Deep infaunal taxa become increasingly rare. (4) At the lower slope and abyssal plane stations (deeper than 2000 m), faunal densities are very low and the fauna is composed exclusively by shallow infaunal species, such as Nuttallides umboniferus and Melonis pompilioides. The foraminiferal data together with the pore water data in the sediment give evidence of the presence of a trophic gradient from very eutrophic settings at the upper continental shelf towards oligotrophic settings at the abyssal area.

Solidification and wetting behaviour of SnAgCu solder alloyed by reactive metal organic flux

Purpose – The purpose of this paper is to develop a new alloying method for solders by using a metal organic modified flux in solder pastes.

An emerging picture of Neoproterozoic ocean chemistry: Insights from the Chuar Group, Grand Canyon, USA

Detailed iron, sulfur and carbon chemistry through the > 742 million year old Chuar Group reveals a marine basin dominated by anoxic and ferrous iron-rich (ferruginous) bottom waters punctuated, late in the basin's development, by an intrusion of sulfide-rich (euxinic) conditions. The observation that anoxia occurred frequently in even the shallowest of Chuar environments (10s of meters or less) suggests that global atmospheric oxygen levels were significantly lower than today. In contrast, the transition from ferruginous to euxinic subsurface water is interpreted to reflect basinal control—specifically, increased export of organic carbon from surface waters. Low fluxes of organic carbon into subsurface water masses should have been insufficient to deplete oxygen via aerobic respiration, resulting in an oxic oxygen minimum zone (OMZ). Where iron was available, larger organic carbon fluxes should have depleted oxygen and facilitated anaerobic respiration using ferric iron as the oxidant, with iron carbonate as the expected mineralogical signature in basinal shale. Even higher organic fluxes would, in turn, have depleted ferric iron and up-regulated anaerobic respiration by sulfate reduction, reflected in high pyrite abundances. Observations from the Chuar Group are consistent with these hypotheses, and gain further support from pyrite and sulfate sulfur isotope abundances. In general, Chuar data support the hypothesis that ferruginous subsurface waters returned to the oceans, replacing euxinia, well before the Ediacaran emergence of persistently oxygenated conditions, and even predating the Sturtian glaciation. Moreover, our data suggest that the reprise of ferruginous water masses may relate to widespread rifting during the break-up of Rodinia. This environmental transition, in turn, correlates with both microfossil and biomarker evidence for an expanding eukaryotic presence in the oceans, suggesting a physiologically mediated link among tectonics, environmental chemistry and life in the dynamic Neoproterozoic Earth system.

Dissolved carbon species in associated diffuse and focused flow hydrothermal vents at the Main Endeavour Field, Juan de Fuca Ridge: Phase equilibria and kinetic constraints

Despite significant advances in the understanding of hydrothermal processes at mid‐ocean ridges, the linkage between focused flow and diffusively flowing vent fluids has remained elusive. Here, we report the distribution of dissolved carbon species in fluids issuing from associated low‐, moderate‐, and high‐temperature vent systems, collected in 2005 at the Main Endeavour Field (MEF), Juan de Fuca Ridge. Excess CO(aq) measured in the moderate‐temperature diffuse flow fluids indicates redox disequilibria between CO(aq) and CO2(aq), suggesting hydrothermal circulation of short residence time in near‐seafloor mixing zones. According to geochemical modeling, the chemical variability of MEF fluids is consistent with a combination of conductive cooling, reaction transport, and subsequent seawater mixing of a single source fluid. The similar distribution of C1‐C3 alkanes observed in diffuse and focused flow fluids likely indicates a minimal fingerprint of biological and methanogenic metabolism on organic fluxes, consistent with a possible short‐lived hydrothermal near‐seafloor circulation. Accordingly, dissolved carbon species in low‐temperature vent fluids can serve as geochemical proxies to distinguish the extent of compositional change in subsurface microbial habitats in the MEF hydrothermal fluids and elsewhere. Part of this reflects conditions unique to the near‐surface, diffuse flow environment, but the flux of components from deeper‐seated hydrothermal processes is important as well. In comparison with earlier measurements (1999 and 2000) of high‐temperature vent fluids at MEF, the 2005 data set exhibits lower Li/Cl ratios and H2(aq) concentrations indicative of higher fluid/rock mass ratios and more oxidizing and/or lower‐temperature conditions, respectively.

A late Miocene–early Pliocene Antarctic deepwater record of repeated iron reduction events

In this study we present a late Miocene–early Pliocene record of sixty-four zones with prominent losses in the magnetic susceptibility signal, taken on a sediment drift (ODP Site 1095) on the Pacific continental rise of the West Antarctic Peninsula. The zones are comparable in shape and magnitude and occur commonly at glacial-to-interglacial transitions. High resolution records of organic matter, magnetic susceptibility and clay mineral composition from early Pliocene intervals demonstrate that neither dilution effects nor provenance changes of the sediments have caused the magnetic susceptibility losses. Instead, reductive dissolution of magnetite under suboxic conditions seems to be the most likely explanation. We propose that during the deglaciation exceptionally high organic fluxes in combination with weak bottom water currents and prominent sediment draping diatom ooze layers produced temporary suboxic conditions in the uppermost sediments. It is remarkable that synsedimentary suboxic conditions can be observed in one of the best ventilated open ocean regions of the World.

Observing novel soil conditioners for carbon emissions mitigation

PurposeThe New Zealand (NZ) Government's commitment to a sustainable, low emissions energy future may be met, in part, by expanding bioenergy systems fuelled by short rotation forestry through utilising lower quality land affecting soil organic matter content and soil CO2 flux. The purpose of this paper is to investigate the carbon sequestration potential of a range of soil conditioners in order to minimise or offset carbon emissions due to ground disturbance.Design/methodology/approachSeven soil conditioners are evaluated using incubation chambers to measure the affect of their incorporation within three NZ soil types on soil respiration.FindingsCharcoal is found to produce a distinct and significant carbon sequestering trend, as do newspaper and whey. Conversely, vegetable oil, paper mill pulp, biodiesel and methanol showed overall carbon emitting trends.Research limitations/implicationsThe research is limited as only CO2 is monitored within the incubation chambers rather than the whole gaseous carbon profile. No microbial observations are conducted.Practical implicationsThe investigation concluded that of the conditioners observed, charcoal, newspaper and whey warrant further observation as carbon sequestration soil conditioners.Originality/valueThe paper forms part of the foundations within the development of soil conditioners specifically designed for carbon sequestration.

Surface–bottom relationships in the Gulf of Salerno (Tyrrhenian Sea) over the last 34 kyr: Compositional data analysis of palaeontological proxies and geochemical evidence

The palaeontological, geochemical and mineralogical records of core GNS84-C106 were analysed in order to reconstruct palaeohydrological changes and palaeoproductivity patterns in the Gulf of Salerno for the last 34 kyr. This approach, including compositional analysis of planktonic and benthic assemblages, gave an insight into the relationships between continental, sea surface and bottom environmental changes. The main source of variability of planktonic and benthic assemblages is related respectively to sea surface temperature and palaeobathymetry. Interrelated changes in surface salinity, nutrients, density gradient in the water column and organic fluxes at the bottom act as a secondary factor controlling the composition of both planktonic and benthic assemblages. The highest palaeoproductivity rates were reached during an interval spanning from late glacial to Middle Holocene, in conditions of enhanced continental run-off. During the Early and Middle Holocene, reduced surface salinity and density stratification were also coupled with the development of a deep chlorophyll maximum and enhanced flux or organic matter at the bottom. From about 6.5 kyr B.P. onward, a sharp reduction in palaeoproductivity took place, coupled with an increase in surface salinities.

Abrupt climate change, sea surface salinity and paleoproductivity in the western Mediterranean Sea (Gulf of Lion) during the last 28 kyr

The planktonic foraminiferal record of core MD99-2346 (Gulf of Lion) shows a decrease of sea surface temperature (SST) at the time of Heinrich event H2 (24–23.5 cal kyr BP), Younger Dryas and during the early to middle Holocene. These events were associated with a decrease of surface water salinity. The salinity lowering events were similar and synchronous to those recorded in the North Atlantic Ocean during H1, H2 and the Younger Dryas. They can be explained by a decrease in the salinity of the Atlantic surface water entering the Mediterranean through the Strait of Gibraltar. This result indicates that the Mediterranean Sea remained a concentration basin and that its freshwater budget was not significantly different from the modern conditions at the time of these low salinity events. Higher abundances of the benthic foraminifer Cibicidoides pachydermus at the time of Heinrich events (H2 and H1) may result from a seasonal, and more pulsed supply of labile organic matter. A high abundance of intermediate and deep infaunal taxa ( Globobulimina spp.) during the warm Bölling/Alleröd period is interpreted as a result of an increased lateral advection of organic matter to the deeper environments of the Gulf of Lion. Surface water productivity, as reflected by the organic flux to the benthic ecosystem, reaches a maximum during the cold Younger Dryas period. It is possible that cold conditions at the time of the Younger Dryas have allowed an enhanced vertical mixing and deep-water cascading in the Gulf of Lion. This may have resulted in an increase of primary and export production. This putative intensification of deep-water cascading would have occurred after the sustained rise of the global sea-level from 16 to 12.5 cal kyr BP. The deglacial sea-level rise may also have played an important role in favouring the downslope movement of dense shelf water enriched in organic matter originating from the early Rhône delta complex. The conditions during the Holocene were characterized by a low surface productivity and oligotrophic environment similar to the modern situation.

Large-scale variation in macrofaunal communities along the eastern Nordic Seas continental margin: A comparison of four stations with contrasting food supply

A hypothesis-driven approach was used to examine the relative importance of pelagic and advective organic flux as drivers of macrofaunal community structure at mid-slope (900–1400 m) depths along the eastern Nordic Seas margin. Ice-free stations were sampled on the Vøring Plateau (VP, mainly pelagic flux) and Bear Island Fan (BIF, major downslope advection). Seasonally ice-covered stations with episodic inputs of fresh phytodetritus were located on the Svalbard Margin (SM, major current-driven advective input), and Yermak Plateau (YP, low advective input). Macrofaunal biomass was higher at stations with seasonal ice cover, suggesting a greater supply of bioavailable organic matter in the marginal ice zones. At VP, BIF and SM, box corer and multiple corer samples gave broadly consistent community data. Very large infauna in box corer samples from YP indicated the existence of a faunal component absent or not sampled at the other three stations. This faunal component and higher mean body size for 18 out of 23 major taxa at YP relative to VP was consistent with a hypothesis relating body size to interannual variability of sinking flux, but was confounded by a depth difference between the two stations. Consistent with predictions, taxa associated with subsurface ‘caching’ of fresh organic matter were important community elements at stations experiencing episodic pelagic input, but not at the advection-dominated BIF. Current-driven advective flux was associated with high suspension-feeder biomass at BIF, but not at SM. The predicted high representation of subsurface deposit-feeders at BIF was not found. Sipunculans ( Nephasoma sp.) known to rapidly subduct fresh organic matter were found at all stations but were most abundant at VP. Comparison with data from the mid-1980s showed a large difference in estimated macrofaunal abundance on the Vøring Plateau, but good agreement in biomass. Community patterns on the Vøring Plateau were generally consistent with earlier data. Standing stock estimates from the Svalbard Margin and Yermak Plateau also agreed well with previous data. Results suggest that large-scale contrasts in organic flux can be used to predict some aspects of bathyal macrofaunal community composition in the Nordic Seas.