Anisotropy of the hectometer cosmic radio background

The angular anisotropy of cosmic radio emission at frequencies of 260, 512, 772, and 1028 kHz was studied on the WIND spacecraft when it moved to a distance of ~1.5×10⁶ km from the Earth at the deepest phase of the last solar minimum. The modulation index of the temperature of the spacecraft dipole antenna rotating in the plane of the ecliptic was found to have an indistinct frequency dependence with a maximum of 17% near 500 kHz. This result modifies significantly the conclusions of the only similar experiment on the IMP-6 spacecraft carried out under less favorable observing conditions. Existing ideas about the causes of the radio-background anisotropy in the opacity region of the Galactic gas disk are briefly reviewed.     

Economic feasibility of using offshore oil and gas structures in the Gulf of Mexico for platform-based aquaculture

The increasing global demand for animal protein is a major ecological concern due to its impacts on land use, climate change, global grain supply and fisheries. One method for harvesting animal protein is to grow marine fish. This is widely practiced in coastal environments, but also leads to environmental problems associated with habitat loss and nutrient loading. One alternative is to move marine aquaculture further offshore, away from coastal land-use conflicts and towards ocean currents, which can efficiently dispose wastes. This concept creates a logistical challenge, however, since operators have to transport large amounts of food, fish and fuel to and from offshore cages on a regular basis and in varied weather conditions. In this paper, we discuss the economic feasibility of using offshore oil and gas platforms as bases for open ocean aquaculture in the Gulf of Mexico. We develop net-present value models of a platform-based operation and describe sensitivity analysis of the model output. We conclude that offshore platform-based mariculture may be commercially viable under favorable assumptions, that its viability requires economies of scale and depends principally on the yield per unit of cage volume achieved. The limitations of the analysis are described.     

The liver of wrasse - morphology and function as a mirror of point source chemical impact.

Corkwing wrasse (Symphodus melops L.), a protogynous, non-migratory lipfish species, living close to rocky shores was chosen as an indicator species for the monitoring of biological effects of contaminants. Fish were caught by local fisherman at the Norwegian west coast in fjord sites within the framework of the EU BEEP project. The sites represented different point source impacts of (I) copper (a former copper mine), (II) polycyclic aromatic hydrocarbons (PAHs, aluminium smelter discharge), (III) formaldehyde plus PAHs (kelp-factory and influence of the aluminium smelter). Livers of wrasse were studied for histopathological alterations and compared to healthy livers of fish from a reference location. Besides liver morphology, different functional and metabolic parameters were measured to link pathological alterations to functional disorders. The integrity of the lysosomal compartment was tested by the assessment of lysosomal membrane stability (lys), and the accumulation of neutral lipids and lipofuscin. Activity and intracellular localisation of the NADPH-producing enzymes in the liver were assessed histochemically and measured by computer-assisted image analysis. Histopathological alterations were most severe at the site impacted by formaldehyde and PAHs. These findings were associated with highest tumor prevalence, lowest membrane stabilities in hepatocytes and highest accumulation rates of lipofuscin in the liver. The activities of the NADPH-producing enzymes phosphogluconate dehydrogenase (PGDH) and glucose-6-phosphate dehydrogenase (G6PDH) were significantly lower compared to unimpacted reference fish. Histopathological alterations showed clear differences dependent on the input source. Potential links between specific contaminant impact and functional and morphological disorders are discussed.     

The impact of the 2005 hurricane season on the Louisiana Artificial Reef Program

The 2005 hurricane season in the Gulf of Mexico was the worst in the history of offshore production, with Hurricanes Katrina and Rita destroying 110 oil and gas structures and eight mobile offshore drilling units. Infrastructure destroyed by accident or natural catastrophe are decommissioned according to the same federal regulations that guide normal decommissioning operations, but depending on the nature of the destruction and the market conditions in the months following the event, special conditions and delays may occur. Historically, offshore infrastructure destroyed by hurricanes or other unusual circumstances have been considered for inclusion in the Louisiana Artificial Reef Program (LARP) under the Special Artificial Reef Site (SARS) category. The purpose of this paper is to review the impact of the 2005 hurricane season on the LARP and the current status of the SARS program. We examine the criteria employed in project evaluation and approval as well as aggregate program statistics. The characteristics and risks associated with decommissioning destroyed infrastructure are also described. At the end of 2006, 10 projects representing 35 platforms destroyed in the 2005 hurricane season have been approved as SARS in the Gulf of Mexico, effectively doubling the number of sites and structures classified as SARS.     

Geostandards and Geoanalytical Research Bibliographic Review 2019

This bibliographic review gives an outline of publications in 2019 focusing on reference materials (RMs) used in geochemistry and related fields, such as palaeoclimate and environmental research.     

A study of lignin degradation in leaf and needle litter using C-labelled tetramethylammonium hydroxide (TMAH) thermochemolysis: Comparison with CuO oxidation and van Soest methods

We studied the degradation of lignin in leaf and needle litter of ash, beech, maple, pine and spruce using ¹³C-labelled tetramethylammonium hydroxide (¹³C TMAH) thermochemolysis. Samples were allowed to decompose for 27 months in litter bags at a German spruce forest site, resulting in a range of mass loss from 26% (beech) to 58% (ash). In contrast to conventional unlabelled TMAH thermochemolysis, ¹³C-labelling allows thermochemolysis products from lignin, demethylated lignin and other polyphenolic litter compounds (e.g. tannins) to be distinguished. Proxies for lignin degradation (phenol yield; acid/aldehyde ratio of products) changed considerably upon correction for the contribution of non-lignin sources to the thermochemolysis products. Using the corrected values, we found increasing acid/aldehyde values as well as decreasing or constant yield of lignin derived phenols normalised to litter carbon, suggesting pronounced lignin degradation by wood-rotting fungi. No indication for build up of demethylated lignin through the action of brown rot fungi on ring methoxyls was found. The results were compared with those of other analytical techniques applied in previous studies. Like ¹³C-TMAH thermochemolysis, CuO oxidation showed increasing lignin oxidation (acid/aldehyde ratio) and no/little enrichment of lignin derived phenols in the litter. Molecular lignin degradation patterns did not match those from analysis of total acid unhydrolysable residues (AURs). In particular, the long assumed selective preservation of lignin during the first months of litter decomposition, based on AUR analysis, was not supported by results from the CuO and ¹³C TMAH methods.     

Multiproxy Analyses of Stratigraphy and Palaeoenvironment of the Late Palaeolithic Grabow Floodplain Site,Northern Germany

Changing river courses and fluctuations of the water table were some of the most fundamental environmental changes that humans faced during the Late Glacial, particularly as these changes affected areas intensively used for settlement and resource exploitation. Unfortunately, only a few stratigraphies have been documented in the North European plain that show the interaction between river development, vegetation history, and occupation by Late Palaeolithic humans. Here, we present the results of detailed stratigraphical studies (pedology, archaeology, chrono‐, tephra‐, and palynostratigraphy) at the Federmesser site Grabow 15 located in the broad Elbe River valley. The research aimed to produce a model of site formation based on a multiproxy approach, relating the local evidence to the palaeoenvironmental and settlement history of the wider region. After deposition of fluvial sands during the Late Pleniglacial in a braided setting, the river course developed locally toward a meandering system at the transition from the Older Dryas to the Allerød, while periodic flooding led to the deposition of floodplain sediments during the early Allerød. The floodplain was settled by people of the earliest “Federmessergruppen,” who are believed to have chosen this open floodplain area along the river for collecting and processing amber of local origin. Their artifacts became embedded in the aggrading floodplain sediments. In the late Allerød, floodplain sedimentation ceased and a Fluvisol‐type soil developed, indicating a trend toward geomorphic stability. The Fluvisol was then covered by silty floodplain sediments due to a rising water level during the late Younger Dryas resulting in the cessation of human occupation in the area. Subsequent organic‐rich Late Glacial/Holocene sediments preserved the settlement remains to the present.     

Integrating Fire Behavior and Pedestrian Mobility Models to Assess Potential Risk to Humans from Wildfires Within the U.S.–Mexico Border Zone∗

Wildfires create a risk to pedestrians traveling through rural areas, because they might not be aware of the presence of a wildfire or its direction and rate of spread until is too late to successfully evacuate. In wildland areas of southern San Diego County, immigrants crossing the U.S.–Mexico border and border security agents are particularly at risk to wildfires. The objective of this study is to develop a framework of analysis and associated tools for examining the combined behavior of wildfires and pedestrian mobility to assess the potential threat of fire to pedestrians in wildland areas. Outputs from a geographic information system (GIS) overlay model for determining potentially dangerous fire zones, the Wildland–Urban Interface Evacuation (WUIVAC) model, and a model of pedestrian mobility in wildland areas were combined to generate wildfire risk to pedestrian maps. The key technical contributions of the study are the development and testing of the pedestrian mobility model and the framework and logic for integrating the results of three GIS-based models. The applied geography contribution is the testing of two scenarios of high risk from wildfires to pedestrians within the U.S.–Mexico border zone of San Diego County, California.

The study results show that the travel times calculated by the pedestrian mobility model appear to be realistic and are affected by the terrain and vegetation characteristics of a study site, whereas the evacuation trigger buffers (ETBs) from WUIVAC are mostly influenced by the wind speed and direction parameters of the FlamMap fire spread model. A moderate fire danger to pedestrians in the most remote wildland locations of the study area is determined. The scenario test results suggest that if a wildfire occurs within 2 km (extreme southwesterly winds) or 6 km (extreme northeasterly wind) of pedestrians in the worst case location within the San Diego border region they would likely not have a sufficient amount of time to reach a nearby safety zone.     

A Royalty Revenue Forecast Model for Louisiana

Louisiana receives royalty revenue when minerals are produced on state-owned lands and water bottoms, federal properties within the state, and offshore fields underlying federal and state jurisdiction within 3–6 nautical miles from the coastline. Royalty revenue on oil and gas production has averaged $465 million per year and has contributed 3–7% of the state general revenue over the past decade. The purpose of this article is to develop a royalty revenue forecast model to assist in state budgeting and planning purposes. Producing fields are evaluated within a probabilistic framework to capture the uncertainty associated with future capital outlays and operational changes, and a discovery model is used to generate production from fields expected to be discovered in the future. The forecasts are combined with commodity price scenarios and royalty rate assumptions to generate a royalty revenue outlook for the state. We estimate that cumulative royalty revenue during 2012–2017 will range from $704 million to $1,408 million for oil production and from $286 million to $1,145 million for gas production for commodity prices of 60–120 $/bbl and 2–8 $/Mcf. At $80/bbl and $4/Mcf, cumulative royalty receipts from 2012 to 2017 are estimated at $1,510 million.     

iShocks: X-ray binary jets with an internal shocks model

In the following paper, we present an internal shocks model, iShocks, for simulating a variety of relativistic jet scenarios; these scenarios can range from a single ejection event to an almost continuous jet, and are highly user configurable. Although the primary focus in the following paper is black hole X-ray binary jets, the model is scale and source independent and could be used for supermassive black holes in active galactic nuclei or other flows such as jets from neutron stars. Discrete packets of plasma (or 'shells') are used to simulate the jet volume. A two-shell collision gives rise to an internal shock, which acts as an electron re-energization mechanism. Using a pseudo-random distribution of the shell properties, the results show how for the first time it is possible to reproduce a flat/inverted spectrum (associated with compact radio jets) in a conical jet whilst taking the adiabatic energy losses into account. Previous models have shown that electron re-acceleration is essential in order to obtain a flat spectrum from an adiabatic conical jet: multiple internal shocks prove to be efficient in providing this re-energization. We also show how the high-frequency turnover/break in the spectrum is correlated with the jet power,  ν _b ∝ L ^∼0.6_W  , and the flat-spectrum synchrotron flux is correlated with the total jet power,   F _ν∝ L ^∼1.4_W  . Both the correlations are in agreement with previous analytical predictions.