Comparison of fouling of raw milk and whey protein solution on stainless steel and fluorocarbon coated surfaces: Effects on fouling performance, deposit structure and composition

Fouling from raw milk and from whey protein solutions mimicking the protein content of milk have been performed at two length scales, using a microfluidic heat transfer cell and a bench-scale device with hydraulic diameters 1:0mm and 16:1 mm, respectively. The microfluidic cell allows raw milk to be studied in once-through mode and was used to identify polymer coated surfaces to test against stainless steel. Several of the fluorocarbon coated surfaces reduced the mass deposition but the pressure drop and thermal resistance did not match these directly, indicating that the nature and structure of the deposit is affected by the surface. A fluorinated ethylene propylene coating was identified as a promising candidate for large scale tests. At the interface with apolar surfaces, raw milk fouling layers were high in protein whereas a strongly attached mineral-rich layer was present at the interface with steel. The attraction of denatured protein towards apolar surfaces and the formation of a calcium phosphate layer on steel at later stages of fouling are explained with arguments based on the interfacial free energy of these materials in water.The work was funded by Chemours Belgium BVB

Antarctic ice sheet sensitivity to atmospheric CO2 variations in the early to mid-Miocene

Geological records from the Antarctic margin offer direct evidence of environmental variability at high southern latitudes and provide insight regarding ice sheet sensitivity to past climate change. The early to mid-Miocene (23-14 Mya) is a compelling interval to study as global temperatures and atmospheric CO2 concentrations were similar to those projected for coming centuries. Importantly, this time interval includes the Miocene Climatic Optimum, a period of global warmth during which average surface temperatures were 3-4 °C higher than today. Miocene sediments in the ANDRILL-2A drill core from the Western Ross Sea, Antarctica, indicate that the Antarctic ice sheet (AIS) was highly variable through this key time interval. A multiproxy dataset derived from the core identifies four distinct environmental motifs based on changes in sedimentary facies, fossil assemblages, geochemistry, and paleotemperature. Four major disconformities in the drill core coincide with regional seismic discontinuities and reflect transient expansion of grounded ice across the Ross Sea. They correlate with major positive shifts in benthic oxygen isotope records and generally coincide with intervals when atmospheric CO2 concentrations were at or below preindustrial levels (∼280 ppm). Five intervals reflect ice sheet minima and air temperatures warm enough for substantial ice mass loss during episodes of high (∼500 ppm) atmospheric CO2. These new drill core data and associated ice sheet modeling experiments indicate that polar climate and the AIS were highly sensitive to relatively small changes in atmospheric CO2 during the early to mid-Miocene

Physical Properties of the AND-1B Core, ANDRILL McMurdo Ice Shelf Project, Antarctica

Whole-core physical properties of the AND-1B sediment core were determined on site for initial core characterisation and correlation with seismic modelling to predict target-reflector depth. This was accomplished by the application of a GEOTEK MSCL (multisensor core logger) from which detected parameters were converted to wet bulk density (WBD), P-wave velocity (Vp), and magnetic susceptibility (MS). Due to difficulties in terms of sensor drift, non-contact resistivity (NCR) data were not processed on site. Standards were logged together with the cores throughout the entire depth range to monitor data quality and demonstrate that no systematic offsets occurred between different core diameters of the AND-1B core (PQ-liner, PQ, HQ, and NQ). Physical properties exhibit a large range of values, reflecting the different nature of the various lithologies including clasts, effects of cementation, and overall downcore gradients in WBD and Vp as a result of compaction. Generally, the boundaries of the major stratigraphic units are in good agreement with changes in the pattern of the physical properties. WBD, Vp, and MS exhibit remarkable cyclicities in particular in the upper part of the core down to about 600 metres below seafloor (mbsf)

Physical Properties of the AND-2A Core, ANDRILL Southern McMurdo Sound Project, Antarctica

Whole-core measurements of Wet Bulk Density (WBD), compressional (P)-wave velocity (Vp), and Magnetic Susceptibility were measured at a sampling interval of 1 or 2 centimetres (cm) throughout the AND-2A drill core for initial core characterisation and on-site correlation with seismic modeling to predict target-reflector depth. Measurements were made using a GEOTEK (Multi-Sensor-Core-Logger MSCL). Density and velocity standards were measured together with core runs of 3-6 metres (m) (and occasionally up to 18 m) throughout the entire depth range to monitor data quality. Drift of the magnetic susceptibility sensor was also monitored and corrected where necessary. These physical properties show a large range of values, reflecting the different nature of the various lithologies including extremely high velocity and density values in individual clasts, and the effects of cementation on porosity. A downcore increase in WBD and Vp occurs in the upper 200 m, however, no systematic trend exists at greater depths although large fluctuations on a m-decimetre- (dm) scale occur. Magnetic susceptibility is generally low (\u3c100 x\u3e10-5 SI), however, four intervals of high (\u3e600 x 10-5 SI) susceptibility occur at 560, 800, 980 and 1 080 mbsf, indicating a relatively greater contribution of volcanic-derived material to the core site in the lower half of the AND-2A core

The physical properties record of the AND-1B sediment core A quantitative approach to describing past ice shelf/ice sheet dynamics

In austral summer 2006/07 a more than 1200 m long sediment core was drilled beneath McMurdo Ice Shelf near Ross Island (Antarctica) with the purpose of contributing to a better understanding of the Late Cenozoic history of the Antarctic Ice Sheet (ANDRILL-MIS Project). Dating back to about 13 Ma this core offers the great potential to study the long-term global cooling trend at an ice-proximal location. High-resolution multi-sensor core logger measurements of whole-core physical properties serve as a numerical expression of lithologic changes in the core and therefore, represent a quantitative tool for approaching past ice dynamics. This is especially applicable for the repeating sequences of diatomites and diamtictites in the upper half of the core with a prominent cyclicity between 140-300 mbsf. Rather abrupt high-amplitude variations in wet-bulk density (WBD) and magnetic susceptibility (MS) reflect rapid changes between two main end-member facies generated by the alternation between a grounded ice sheet and open marine conditions. For the whole core, the WBD signal, ranging from 1.4 kg/cu.m in the diatomites to 2.3 kg/cu.m in diamitctites from the lower part of the core, represents the influence of three variables: (i) the degree of compaction seen as reduced porosities with depth from about 55 % in the top part to about 25 % at the bottom, (ii) the clast content with clasts being almost absent in diatomite deposits and (iii) the individual grain density (GD). GD itself ranges from about 2.15 kg/cu.m in diatomites to 2.9 kg/cu.m for volcanic sandstones and thereby reflects the variety of lithologies as well as the influence of cement (mainly pyrite and carbonate) on the matrix grain density. The calculation of residual porosities demonstrates the strong imprint of glacial loading for especially diamictites from the upper 150 m. This over-consolidation signature preserved in the sediments can be used to characterize the Pleistocene ice sheet in terms of ice thickness derived from past stresses. MS on the other hand mainly documents a marine vs. terrestrial source of sediments where the latter can be divided into younger local material from the McMurdo Volcanic Province and basement clasts from the Transantarctic Mountains. Values range over several orders of magnitude from <10 (10-5 SI) in the diatomites to 8000 (10-5 SI) in single clasts (mainly dolerite). Synchronous minima and maxima in both WBD and MS support dramatic changes in the depositional environment, driven by oscillations in ice extent in response to climate fluctuations. According to the age model, cyclicity occurs on Milankovich timescales with changes in obliquity being the dominant forcing until the Early Pleistocene. Additionally, small-amplitude variations within diatomite units propose sub-Milankovich forcing as superimposed control on system dynamics

Porosity and density of the AND-1B sediment core, McMurdo Sound region, Antarctica: Field consolidation enhanced by grounded ice

A study of density and porosity is presented for the 1285-m-long AND-1B core recovered from a flexural moat in the McMurdo Sound (Antarctica) in order to interpret sediment consolidation in an ice-proximal location on the Antarctic shelf. Various lithologies imply environmental changes from open marine to subglacial, and are numerically expressed in high-resolution whole-core wet-bulk density (WBD). Grain density data interpolated from discrete samples range from 2.14 to 3.85 g/cm3 and are used to calculate porosity from WBD in order to avoid the 5�15 overestimation and underestimation of porosities obtained by standard methods. The trend of porosity extends from 0.5 near the top (Pleistocene) to 0.2 at the bottom (Miocene). Porosity fluctuations in different lithologies are superimposed with 0.2�0.3 in sequences younger than ca. 1 Ma and 0.5�0.8 in Pliocene diatomites. The AND-1B porosities and void ratios of Pliocene diatomites and Pleistocene mudstones exhibit a large negative offset compared to modern lithological analogs and their consolidation trends. This offset cannot be explained in terms of the effective stress at the AND-1B site. The effective stress ranges from 0 to 4000 kPa in the upper 600 m, and reaches 13,000 kPa at the base of the AND-1B hole. We suggest an excess of effective overburden stress of �1700 and �6000 kPa to explain porosities in Pliocene diatomites and Pleistocene mudstones, respectively. This is interpreted as glacial preconsolidation by subsequently grounded ice sheets under subpolar to polar, followed by colder polar types of glaciations. Information on Miocene consolidation is sparse due to alteration by diagenesis

Past warmer climate periods at the Antarctic margin detected from proxies and measurements of biogenic opal in the ABD-1B core: the XRF spectral silver (Ag) peak used as a new tool for biogenic opal quantification

Quantification of biogenic opal in marine sediments is a time consuming job, but the results could indicate periods of higher bioproductivity and warmer conditions than today at the Antarctic margin. Within the international Antarctic Geological Drilling Program (ANDRILL), core AND-1B was drilled and recovered a 1285 m sequence from a flexural moat basin filled with glacimarine, terrigenous, volcanic and biogenic sediments below the McMurdo Ice Shelf. Our main goal is to study the variability and the stability of the Ross Ice Shelf from Miocene to Recent. The melting and collapse of large Antarctic ice shelves may cause a significant sea level rise because of accelerated inland ice glacier surges into the ocean. Biogenic opal content in sediments can be deduced indirectly from grain density measurements on single samples, or faster and more continuous by gamma ray attenuation measurements on the core, with subsequent wet bulk and grain density calculations. Spectral colour reflectance (b* value) measurements on the split core surface can also be a fast tool for opal content quantification. Of course, they all have disadvantages in comparison to direct measurement on samples using X-ray diffraction or geochemical leaching methods. Some major and minor chemical elements were measured directly on split core surfaces with a non- destructive X-Ray Fluorescence Core Scanner method (XRF-CS, Avaatech) in the field. Quantitative geochemical analyses like determination of total inorganic and organic carbon (TOC), biogenic opal as well as major and minor elements were done on core samples. We found a strong positive correlation between the counts per second of the XRF-CS Ag peak area and the biogenic opal content of the samples (r=0.81) not only in the AND-1B core but in others as well from the Antarctic margin. In literature, it is noted that diatoms could accumulate Ag in sediments, so at first we were pleased to find this Ag enrichment with our tool. But further geochemical analyses revealed that measuring these low Ag concentrations and their variability (< 2ppm) is not possible or at least problematic with the XRF-CS. The detector of the XRF-CS has an Ag collimator, possibly acting as an amplifier on perhaps higher induced X-ray emissions in opal rich sediments within the Ag energy spectrum range, which might have nothing to do with Ag itself. However, we are still studying the physics behind this measurement phenomenon. Nevertheless, this Ag peak can be used as a proxy for biogenic opal concentrations. It is negatively correlated to Fe and Ti and variability downcore has a high signal to noise ratio. Combining the opal calculations from fast measurements of the Ag peak (opal-Ag), the grain density (opal-GD), and the b* value (opal-b*) we yielded a new multi-parameter proxy (opal-MP) for a high-resolution record of biogenic opal concentration in the upper 600m of the core (spacing: about 2cm or 300y). This opal-MP proxy correlates very well with measured opal leaching data (r=0.88, n=481). The biogenic opal concentrations in combination with other high-resolution data will be used as a cyclostratigraphic approach to understand paleoenvironmental and climate changes. Periods with much higher accumulation of biogenic opal than today were detected in the core that indicate a retreat and perhaps a total decay of the Ross Ice Shel

Periglacial landscape evolution and environmental changes of Arctic lowland areas for the last 60,000 years (Western Laptev Sea coast, Cape Mamontov Klyk)

Non-glaciated Arctic lowlands in north-east Siberia were subjected to extensive landscape and environmental changes during the Late Quaternary. Coastal cliffs along the Arctic shelf seas expose terrestrial archives containing numerous palaeoenvironmental indicators (e.g., pollen, plant macro-fossils and mammal fossils) preserved in the permafrost. The presented sedimentological (grain size, magnetic susceptibility and biogeochemical parameters), cryolithological, geochronological (radiocarbon, accelerator mass spectrometry and infrared-stimulated luminescence), heavy mineral and palaeoecological records from Cape Mamontov Klyk record the environmental dynamics of an Arctic shelf lowland east of the Taymyr Peninsula, and thus, near the eastern edge of the Eurasian ice sheet, over the last 60 Ky. This region is also considered to be the westernmost part of Beringia, the non-glaciated landmass that lay between the Eurasian and the Laurentian ice caps during the Late Pleistocene. Several units and subunits of sand deposits, peat–sand alternations, ice-rich palaeocryosol sequences (Ice Complex) and peaty fillings of thermokarst depressions and valleys were presented. The recorded proxy data sets reflect cold stadial climate conditions between 60 and 50 Kya, moderate inderstadial conditions between 50 and 25 Kya and cold stadial conditions from 25 to 15 Kya. The Late Pleistocene to Holocene transition, including the Allerød warm period, the early to middle Holocene thermal optimum and the late Holocene cooling, are also recorded. Three phases of landscape dynamic (fluvial/alluvial, irregular slope run-off and thermokarst) were presented in a schematic model, and were subsequently correlated with the supraregional environmental history between the Early Weichselian and the Holocene