Thermal and pressure stability of myrosinase enzymes from black mustard (Brassica nigra L. W.D.J Koch. var. nigra), brown mustard (Brassica juncea L. Czern. var. juncea) and yellow mustard (Sinapsis alba L. Subsp Maire) seeds

This study investigates the effects of temperature and pressure on inactivation of myrosinase extracted from black, brown and yellow mustard seeds. Brown mustard had higher myrosinase activity (2.75 un/mL) than black (1.50 un/mL) and yellow mustard (0.63 un/mL). The extent of enzyme inactivation increased with pressure (600-800 MPa) and temperature (30-70 °C) for all the mustard seeds. However, at combinations of lower pressures (200-400 MPa) and high temperatures (60-80 °C), there was less inactivation. For example, application of 300 MPa and 70 °C for 10 minutes retained 20%, 80% and 65% activity in yellow, black and brown mustard, respectively, whereas the corresponding activity retentions when applying only heat (70 °C, 10min) were 0%, 59% and 35%. Thus, application of moderate pressures (200-400 MPa) can potentially be used to retain myrosinase activity needed for subsequent glucosinolate hydrolysis

A Range Extension of the Atlantic Silverside, Menidia menidia, to Coastal Waters of Southwestern Newfoundland

Previous literature documents Atlantic Silverside, Menidia menidia, as occurring from the southern Gulf of St. Lawrence to northeastern Florida. Beach seining in St. George’s Bay, Newfoundland, revealed the presence of this species in coastal waters of southwestern Newfoundland. This is the first documented report of M. menidia in Newfoundland waters. This report extends the range of this species north of the Laurentian Channel, a significant biogeographic barrier to small coastal fishes. All M. menidia collected were young-of-the-year, less than 90 mm SL (Standard Length). These fish may be representative of a larger relict population originating from the Mid-Hypsithermal Interval (7000 years ago) that spawn in St. George’s Bay and migrate offshore for winter. Alternatively, these M. menidia may be survivors of a more southern spawning population carried northward by ocean currents

Fungal Spore Dispersal by the Eastern Box Turtle (Terrapene carolina carolina)

Although spores from most macrofungi are wind- or water-dispersed, dispersal may also occur via biotic vectors. The Eastern box turtle (Terrapene carolina carolina) is a facultative mycovore that may play an important role in fungal spore dispersal although, to date, no information exists on fungi occurring in fecal samples of box turtles or on the ecological significance of box turtles as spore dispersal vectors. Consequently, a study of the potential for Eastern box turtles to act as vectors for spore dispersal was initiated by capturing wild turtles and collecting fecal samples. Serial dilutions from fecal samples were made to enumerate spores, quantify the number of spores per gram of fecal material and to isolate and identify fungi. Fungal spores were found to be extremely abundant throughout all samples. Fecal samples from 36 turtles yielded a total of 23 different fungal taxa in the Zygomycota, Ascomycota and Basidiomycota. Two yeasts that were isolated, Cryptococcus albidus and Rhodotorula mucilaginosa, are reported to naturally occur on Trifolium seeds found in fecal samples. A mold previously unreported from fecal material, Aspergillus wentii, was also found in fecal samples. Data collected suggests Eastern box turtles influence fungal spore dispersal by browsing on plant materials and defecating large numbers of fungal spores within their home ranges

The contrast between Atlantic and Pacific surface water fluxes

The Atlantic Ocean is known to have higher sea surface salinity than the Pacific Ocean at all latitudes. This is thought to be associated with the Atlantic Meridional Overturning Circulation and deep water formation in the high latitude North Atlantic - a phenomenon not present anywhere in the Pacific. This asymmetry may be a result of salt transport in the ocean or an asymmetry in the surface water flux (evaporation minus precipitation; E − P ) with greater E − P over the Atlantic than the Pacific. In this paper we focus on the surface water flux. Seven estimates of the net freshwater flux (E − P − R including runoff, R), calculated with different methods and a range of data sources (atmospheric and oceanic reanalyses, surface flux datasets, hydrographic sections), are compared. It is shown that E − P − R over the Atlantic is consistently greater than E − P − R over the Pacific by about 0.4 Sv (1 Sv ≡ 106 m3 s−1). The Atlantic/Pacific E − P − R asymmetry is found at all latitudes between 30◦S and 60◦N. Further analysis with ERA-Interim combined with a runoff dataset demonstrates that the basin E − P − R asymmetry is dominated by an evaporation asymmetry in the northern high-latitudes, but by a precipitation asymmetry everywhere south of 30◦N. At the basin scale, the excess of precipitation over the Pacific compared to the Atlantic (∼ 30◦S - 60◦N) dominates the asymmetry. Also it is shown that the asymmetry is present throughout the year and quite steady from year to year. Investigation of the interannual variability and trends suggest that the precipitation trends are not robust between datasets and are indistinguishable from variability. However, a positive trend in evaporation (comparable to other published estimates) is seen in ERA-Interim, consistent with sea surface temperature increases

Establishing Lagrangian connections between observations within air masses crossing the Atlantic during the International Consortium for Atmospheric Research on Transport and Transformation experiment

The ITCT-Lagrangian-2K4 (Intercontinental Transport and Chemical Transformation) experiment was conceived with an aim to quantify the effects of photochemistry and mixing on the transformation of air masses in the free troposphere away from emissions. To this end, attempts were made to intercept and sample air masses several times during their journey across the North Atlantic using four aircraft based in New Hampshire (USA), Faial (Azores) and Creil (France). This article begins by describing forecasts from two Lagrangian models that were used to direct the aircraft into target air masses. A novel technique then identifies Lagrangian matches between flight segments. Two independent searches are conducted: for Lagrangian model matches and for pairs of whole air samples with matching hydrocarbon fingerprints. The information is filtered further by searching for matching hydrocarbon samples that are linked by matching trajectories. The quality of these "coincident matches'' is assessed using temperature, humidity and tracer observations. The technique pulls out five clear Lagrangian cases covering a variety of situations and these are examined in detail. The matching trajectories and hydrocarbon fingerprints are shown, and the downwind minus upwind differences in tracers are discussed

A Range Extension of the Atlantic Silverside, Menidia menidia, to Coastal Waters of Southwestern Newfoundland

Previous literature documents Atlantic Silverside, Menidia menidia, as occurring from the southern Gulf of St. Lawrence to northeastern Florida. Beach seining in St. George’s Bay, Newfoundland, revealed the presence of this species in coastal waters of southwestern Newfoundland. This is the first documented report of M. menidia in Newfoundland waters. This report extends the range of this species north of the Laurentian Channel, a significant biogeographic barrier to small coastal fishes. All M. menidia collected were young-of-the-year, less than 90 mm SL (Standard Length). These fish may be representative of a larger relict population originating from the Mid-Hypsithermal Interval (7000 years ago) that spawn in St. George’s Bay and migrate offshore for winter. Alternatively, these M. menidia may be survivors of a more southern spawning population carried northward by ocean currents

Chemical composition observed over the mid-Atlantic and the detection of pollution signatures far from source regions

The atmospheric composition of the central North Atlantic region has been sampled using the FAAM BAe146 instrumented aircraft during the Intercontinental Transport of Ozone and Precursors (ITOP) campaign, part of the wider International Consortium for Atmospheric Research on Transport and Transformation (ICARTT). This paper presents an overview of the ITOP campaign. Between late July and early August 2004, twelve flights comprising 72 hours of measurement were made in a region from approximately 20 to 40°W and 33 to 47°N centered on Faial Island, Azores, ranging in altitude from 50 to 9000 m. The vertical profiles of O3 and CO are consistent with previous observations made in this region during 1997 and our knowledge of the seasonal cycles within the region. A cluster analysis technique is used to partition the data set into air mass types with distinct chemical signatures. Six clusters provide a suitable balance between cluster generality and specificity. The clusters are labeled as biomass burning, low level outflow, upper level outflow, moist lower troposphere, marine and upper troposphere. During this summer, boreal forest fire emissions from Alaska and northern Canada were found to provide a major perturbation of tropospheric composition in CO, PAN, organic compounds and aerosol. Anthropogenic influenced air from the continental boundary layer of the USA was clearly observed running above the marine boundary layer right across the mid-Atlantic, retaining high pollution levels in VOCs and sulfate aerosol. Upper level outflow events were found to have far lower sulfate aerosol, resulting from washout on ascent, but much higher PAN associated with the colder temperatures. Lagrangian links with flights of other aircraft over the USA and Europe show that such signatures are maintained many days downwind of emission regions. Some other features of the data set are highlighted, including the strong perturbations to many VOCs and OVOCs in this remote region

Processes influencing ozone levels in Alaskan forest fire plumes during long-range transport over the North Atlantic

A case of long-range transport of a biomass burning plume from Alaska to Europe is analyzed using a Lagrangian approach. This plume was sampled several times in the free troposphere over North America, the North Atlantic and Europe by three different aircraft during the IGAC Lagrangian 2K4 experiment which was part of the ICARTT/ITOP measurement intensive in summer 2004. Measurements in the plume showed enhanced values of CO, VOCs and NOy , mainly in form of PAN. Observed O3 levels increased by 17 ppbv over 5 days. A photochemical trajectory model, CiTTyCAT, was used to examine processes responsible for the chemical evolution of the plume. The model was initialized with upwind data and compared with downwind measurements. The influence of high aerosol loading on photolysis rates in the plume was investigated using in situ aerosol measurements in the plume and lidar retrievals of optical depth as input into a photolysis code (Fast-J), run in the model. Significant impacts on photochemistry are found with a decrease of 18% in O3 production and 24% in O3 destruction over 5 days when including aerosols. The plume is found to be chemically active with large O3 increases attributed primarily to PAN decomposition during descent of the plume toward Europe. The predicted O3 changes are very dependent on temperature changes during transport and also on water vapor levels in the lower troposphere which can lead to O3 destruction. Simulation of mixing/dilution was necessary to reproduce observed pollutant levels in the plume. Mixing was simulated using background concentrations from measurements in air masses in close proximity to the plume, and mixing timescales (averaging 6.25 days) were derived from CO changes. Observed and simulated O3/CO correlations in the plume were also compared in order to evaluate the photochemistry in the model. Observed slopes change from negative to positive over 5 days. This change, which can be attributed largely to photochemistry, is well reproduced by multiple model runs even if slope values are slightly underestimated suggesting a small underestimation in modeled photochemical O3 production. The possible impact of this biomass burning plume on O3 levels in the European boundary layer was also examined by running the model for a further 5 days and comparing with data collected at surface sites, such as Jungfraujoch, which showed small O3 increases and elevated CO levels. The model predicts significant changes in O3 over the entire 10 day period due to photochemistry but the signal is largely lost because of the effects of dilution. However, measurements in several other BB plumes over Europe show that O3 impact of Alaskan fires can be potentially significant over Europe

The role of boundary layer processes in summer-time Arctic cyclones

Arctic cyclones are the most energetic weather systems in the Arctic, producing strong winds and precipitation that present major weather hazards. In summer, when the sea ice cover is reduced and more mobile, Arctic cyclones can have large impacts on ocean waves and sea ice. While the development of mid-latitude cyclones is known to be dependent on boundary layer (BL) turbulent fluxes, the dynamics of summer-time Arctic cyclones and their dependence on surface exchange processes have not been investigated. The purpose of this study is to characterise the BL processes acting in summer-time Arctic cyclones and understand their influence on cyclone evolution. The study focuses on two cyclone case studies, each characterised by a different structure during growth in the Arctic: (A) low-level-dominant vorticity (warm-core) structure and (B) upper-level-dominant vorticity (cold-core) structure, linked with a tropopause polar vortex. A potential vorticity (PV) framework is used to diagnose the BL processes in model runs from the ECMWF Integrated Forecasting System model. Both cyclones are associated with frictional Ekman pumping and downward sensible heat fluxes over sea ice. However, a third process, the frictional baroclinic generation of PV, acts differently in A and B due to differences in their low-level temperature structures. Positive PV is generated in Cyclone A near the bent-back warm front, like in typical mid-latitude cyclones. However, the same process produces negative PV tendencies in B, shown to be a consequence of the vertically aligned axisymmetric cold-core structure. This frictional process also acts to cool the lower troposphere, reducing the warm-core anomaly in A and amplifying the cold-core anomaly in B. Both cyclones attain a vertically aligned cold-core structure that persists for several days after maximum intensity, which is consistent with cooling from frictional Ekman pumping, frictional baroclinic PV generation, and downward sensible heat fluxes. This may help to explain the longevity of isolated cold-core Arctic cyclones with columnar vorticity structure.</p