Evolution of seafloor pockmarks along the Northern Orange Basin, Offshore South Africa: Interplay between fluid flow and bottom current activities

Pockmarks are pervasive geomorphologic features identified along continental margins resulting from fluid expulsion on the seafloor. However, the understanding of the underlying geological mechanism/control in relation to their evolution, distribution, and morphology is limited, especially along data-starved continental margins such as the Northern Orange Basin. Analysis of a high-quality 3D seismic reflection data reveals at least 50 individual pockmarks, two channel-like depressions and several irregular depressions in water depth ranging between 800 m and 2400 m. Morphologically, the pockmarks are circular, elongated, comet-like and crescentic in shape, with diameters and depths ranging between ∼0.2 - 2.8 km and ∼10 - 130 m, respectively. Preferential alignment of these pockmarks on the seafloor in relation to the axis of underlying turbidite channels, erosional morphologies and mass transport complexes portray a genetic relationship. The slope architecture hints at the possibility of both deep and shallow fluid source driving pockmark formation. Under this scenario, deep thermogenic gas derived from Cretaceous source rocks migrated along fault systems associated with the Late Cretaceous Megaslide complex to the overburden. The fluids are stored/redistributed in contourite and turbidite channels and subsequently focused toward the seafloor under an increased pore pressure regime. Yet, the fluids may be either solely biogenic gas or heterogeneous, incorporating biogenic components and pore-water derived from the channels and dewatering of the contourites. Importantly, the discovery of crescentic and elongated end-member pockmark morphologies indicate post-formation sculpting of the initial pockmark morphologies by bottom currents. The discovery of these deep-water pockmarks opens the possibility that such fluid escape features may be more widespread than currently documented in the Northern Orange Basin. This has implications in understanding of the petroleum system here and their potential role in the South Atlantic marine ecosystems and global climate change in terms of the expulsion of climate forcing gases.

Investigation of the Properties of Large and Small Fractions of Municipal Solid Waste

The results of field and laboratory studies of the component and fractional composition of solid municipal waste (MSW), humidity and ash content of MSW components, which made it possible to evaluate the properties of individual fractions and waste in general, are presented. The fractional composition of MSW was determined by the method of separating waste into five fractions of different sizes: more than 250 mm, 100-250 mm, 50–100 mm, 15–50 mm and less than 15 mm. An assessment of the energy and biological potentials of MSW of various sizes has been carried out. In each fraction, the main biogenic components have been identified, which form the biological potential. The calculation of thermal properties (moisture content, ash, combustible substances, as well as the heat of combustion) for the fractions under consideration has been performed. The dependence of the heat of combustion of MSW on the particle size has been established.

First description of deep benthic habitats and communities of oceanic islands and seamounts of the Nazca Desventuradas Marine Park, Chile

Seamounts and oceanic islands of the Chilean Exclusive Economic Zone at the intersection of the Nazca and Salas y Gómez ridges lie within one of the least explored areas in the world. The sparse information available, mainly for seamounts outside Chilean jurisdiction and shallow-water fauna of the Desventuradas Islands, suggests that the area is a hotspot of endemism. This apparent uniqueness of the fauna motivated the creation of the large Nazca-Desventuradas Marine Park (NDMP, ~ 300,000 km2) around the small islands San Felix and San Ambrosio in 2015. We report for the first time a detailed description of benthic microhabitats (i.e., centimeter to meter scale), macrohabitats (i.e., meter to kilometer-scale) and associated megafauna within the NDMP. Descriptions were based on analysis of fauna collected by trawling and ROV video observations from ~ 50 to 370 m depth. Rocky, coarse sand and silty sediment bottom habitats were observed at island slopes. In contrast, rocky and coarse sandy bottom habitats with a predominance of rhodoliths, thanatocoenosis, and other biogenic components were observed at seamounts. Mobile fauna and predators dominated the oceanic islands and nearby seamounts, whereas seamounts farther from the islands were dominated by sessile and hemisessile fauna that were mainly suspension and deposit feeders. Based on the register of 118 taxonomic units, our results provide an expanded and updated baseline for the benthic biodiversity of NDMP habitats, which seemed pristine, without evidence of trawling or anthropogenic debris.

Astronomical tuning of the Aptian Stage

<p>We present a new astronomical tuning for the Aptian stage, based on the combined record of the Piobbico Core (Umbria-Marche Basin, central Italy - this study) and the Cismon Core (Belluno Basin, northwestern Italy - Malinverno et al., 2010).  Integrated bio-chemostratigraphy is available for both cores, granting their chronostratigraphic characterization and highest correlability.</p><p>A continuous high-resolution greyscale log of the Piobbico Core, obtained after full reprocessing of core photos, was used as input for the cyclostratigraphic analysis. Evolutionary spectral analysis reveals unstable frequencies throughout the record, indicative of uneven sedimentation rates ranging from about 2 to about 9 m/My. Reconstructed sedimentation rate model is based on the optimal fit of the long-eccentricity ~405-kyr-cycle. Changes in accumulation rate were further validated by applying the evolutionary coefficient analysis of the stratigraphic series, with the main components of the La2010a astronomical solution used as targets. Estimated variations in sedimentation rate well reflect the major lithofacies variations, from marlstone-dominated to marly limestone-dominated intervals, and the relative changes in biogenic components along the succession.</p><p>Results of the cyclostratigraphic analysis indicate that orbital forcing controlled the depositional patterns. Visual variations in the greyscale log, further supported by spectral analysis, highlight an evident cyclicity related to long- and short-eccentricity orbital periodicities. The combined short- and long-eccentricity amplitude envelope of the tuned record shows significant long-term modulations in the short eccentricity bands. Frequencies related to precession index fit as well with the La2010a astronomical model. The calibration with the theoretical astronomical solution allowed to define a consistent age model for the studied succession.</p><p>The tuned greyscale log of the Piobbico Core (this study) was merged with the tuned FMI resistivity log of the Cismon Core (Malinverno et al., 2010) in order to obtain a composite record covering the entire Aptian time interval and determine the duration of the Aptian time interval.  In addition, by anchoring the results of the cyclostratigraphy to the U-Pb absolute age of 113.1 ± 0.3 Ma for the Aptian/Albian boundary, we provide a new estimate for the age of the Barremian/Aptian boundary, currently placed at the base of the M0r polarity Chron. The ~405 ky-tuned Piobbico and Cismon merged record indicates a duration of 9.77 My for the Aptian, and an age of 122.87 ± 0.3 Ma for the Barremian/Aptian boundary.</p>

Zróżnicowanie przestrzenne wybranych składników biogennych w śródpolnych oczkach w Polsce Północnej = Spatial differentiation characterising selected biogenic components in mid-field kettle ponds of northern Poland

Closed basins are important and fixed elements of a post-glacial landscape, in which they may occupy rather a large percentage of the total area. Sometimes these fill to become bodies of water known as kettle ponds. Each such basin has its own closed catchment at the surface and, owing to the limited circulation of matter in these types of depressions, biogenic components often accumulate to excess. In that context, the work detailed here had as its main objective the identification of sources of biogenic substances like nitrates, ammonium-nitrogen and phosphates, with a view to determining the range of variability characterising their presence in small mid-field ponds present in the catchments of two of northern Poland’s rivers, i.e. the Parsęta and the Borucinka. Most of the kettle ponds under study could not be said to have particularly high contents of nitrate, given an average for the bodies of water studied within the Parsęta basin equal to 2.98 mg·dm-3. There was nevertheless considerable variability in concentrations of the ion – ranging from 0 to as much as 51.30 mg·dm-3. It was the “Sadkowo” pond that might be singled out here for its extremely high concentration (the aforesaid maximum value of 51.30 mg·dm-3; along with a mean value of 13.41 mg·dm-3). In this case a local factor is likely to have been operating – i.e. areal runoff pollution from fields involving nitrogenous compounds. Ponds in the Borucinka catchment had only low concentrations of nitrate, with a mean value for all kettle ponds studied there of just 0.24 mg·dm-3 (with values in the overall range 0 to 2.17 mg·dm-3). Concentrations of the analysed component were thus lower in the Borucinka catchment than in the Parsęta basin, with a key influencing factor likely to have been the sizes of the bodies of water studied. The Parsęta-basin examples were in fact smaller kettle ponds whose catchment features and morphometric parameters are such as to ensure higher concentrations of biogenic (especially nitrogenous) compounds in any standing waters. Mean concentrations of ammonium ions obtained for the Parsęta basin were of 0‑2.41 mg·dm-3, the value averaged for the six ponds being 0.95 mg·dm-3. However, four other Parsęta-basin ponds excluded from the study in fact reported very high values for NH4 + – of up to 25.55 mg·dm-3. The Borucinka catchment again contrasted with the Parsęta basin, with noted concentrations of ammonium-nitrogen both low and of limited variability (in the 0‑1.88 mg·dm-3 range). The average figures for all the depressions studied there was 0.09 mg·dm-3. The situation as regards the two forms of nitrogen was thus similar, with concentrations lower in the catchment of the Borucinka and higher in the basin of the Parsęta. Sizes of bodies of water would seem to be a factor influencing spatial differentiation of NH4 + concentrations. Where phosphate was concerned, kettle ponds within the Parsęta basin had a mean concentration of 0.57 mg·dm-3, with reported values from one pond to another ranging from 0 to 4.46 mg·dm-3. The Borucinka p ds again had lower concentrations of this biogenic substance across a narrower range of values (0 to 3.69 mg·dm-3, mean 0.19 mg·dm-3).

Appraisal of sedimentary alkenones for the quantitative reconstruction of phytoplankton biomass

Marine primary productivity (PP) is the driving factor in the global marine carbon cycle. Its reconstruction in past climates relies on biogeochemical proxies that are not considered to provide an unequivocal signal. These are often based on the water column flux of biogenic components to sediments (organic carbon, biogenic opal, biomarkers), although other factors than productivity are posited to control the sedimentary contents of the components, and their flux is related to the fraction of export production buried in sediments. Moreover, most flux proxies have not been globally appraised. Here, we assess a proxy to quantify past phytoplankton biomass by correlating the concentration of C37 alkenones in a global suite of core-top sediments with sea surface chlorophyll-a (SSchla) estimates over the last 20 y. SSchla is the central metric to calculate phytoplankton biomass and is directly related to PP. We show that the global spatial distribution of sedimentary alkenones is primarily correlated to SSchla rather than diagenetic factors such as the oxygen concentration in bottom waters, which challenges previous assumptions on the role of preservation on driving concentrations of sedimentary organic compounds. Moreover, our results suggest that the rate of global carbon export to sediments is not regionally constrained, and that alkenones producers play a dominant role in the global export of carbon buried in the seafloor. This study shows the potential of using sedimentary alkenones to estimate past phytoplankton biomass, which in turn can be used to infer past PP in the global ocean.

Average annual background quantity of chemical elements and organic matter in the streams of the "River" environment flowing into Lake Baikal reservoirs

The aim of the article is to assess the average long-term background hydrochemical input of chemical elements and organic matter from the flows of the natural component of the environment "Rivers" flowing into the South, Selenginsky, Middle and North reservoirs of Lake. Baikal. The results of calculation of the average annual amount (g/year) of chemical elements and organic matter (Na+, K+, Ca2+, Mg2+, Al, Si, Mn2+, Feобщ , SO42-, HCO3-, Cl-, NO3-, PO43-, Cr, Cu, Cd, Hg, Pb, Sr, Zn, Co, U, V, Mo, Cорг, Nорг, Pорг, Sорг, CO2, Ti) in the streams of the natural component of the environment "Rivers" flowing into the South, Selenginsky, Sredniy, Severny reservoirs of Lake Baikal are presented. The scale of the river chemical input into the reservoirs and the contribution of the "River" flows to the chemical balances of these reservoirs have been determined. It has been established that only in the Selenga reservoir the rivers carry a significant amount of matter (about 3%). The contribution of river flows to the chemical balance of the reservoir is 3.54; 5.4; 17.5 and 21.5% in the South, Selenga, Middle and North reservoirs, respectively. The rivers flowing into the Selenga reservoir carry 70.6% of the total amount of matter brought by the rivers into the lake. Whereas the rivers of the Northern, Middle and Southern reservoirs carry 14.0; 11.6 and 3.8% of the matter. Only in the Selenga and Northern reservoirs, the rivers (tributaries) are the main sources of macrocomponents (K+, Na+, Ca2+, SO42-, CO3-, Cl-), a number of microcomponents (Rb, Mo, Hg, Sr, and Cu and Zn in the Selenga river-), organic matter (Corgг, Norg, Porg), and biogenic components in the Selenga reservoir (NO3-).

EFFECTIVENESS OF A MODERN LANDFILL LINER SYSTEM IN CONTROLLING GROUNDWATER QUALITY OF AN OPEN HYDROGEOLOGICAL SYSTEM, SE LITHUANIA

The work analyzes data of environmental geological mapping, groundwater monitoring of the region municipal waste landfill. This study examines the effectiveness of a modern landfill liner system in minimizing migration of pollutants in the groundwater of an open hydrogeological system. The results showed that dissolution of carbonates and dilution were the major processes controlling groundwater quality. In the landfill’s direct impact zone, groundwater was only weakly polluted with biogenic components. Increase in concentrations of these chemical components in this zone was related with the groundwater and surface runoff water flowing from adjacent areas. We can state that the modern landfill liner system we analysed is efficient and has no adverse effects on groundwater quality under hydrogeological conditions favourable for the spread of pollutants. However, in case of an accident, pollutants might pose a great threat on the safety of groundwater. Therefore, even modern landfill liner systems are not recommended to be constructed in open hydrogeological systems.

Assessment of the Chemical State of Bottom Sediments in the Eutrophied Dam Reservoir in Poland

The aim of the presented research was to examine the concentration of biogenic compounds and heavy metals in the bottom sediments of the Sulejów Reservoir (Central Poland) from October 2018. Based on the obtained research results, maps of the spatial distribution were prepared. The following parameters were analyzed: total phosphorus (TP), total Kjeldahl nitrogen, total organic carbon (TOC), ratio of total organic carbon to nitrogen (C:N), organic matter content as well as Cd, Cr and Pb concentrations. The sediments were collected at 28 sampling sites, covering the whole area of the reservoir. The differences in the content of individual biogenic compounds result from the composition of the debris applied by the supplying rivers, as well as the content of this elements in the water, long retention time (40 days) and depth from which the tested sediments were taken. The distribution of examined compounds was largely influenced by the agricultural activity in the studied area, as well as the presence of ports and recreational points. Based on the measurements, the highest amounts of biogenic components deposit in sediments of deep parts in slow-flowing waters, in stagnation zones, areas adjacent to arable land, and the sites where fine-size fractions prevail in the deposited material. Biogenic compounds in sediments of the Sulejów Reservoir showed a pattern of gradual increase along the reservoir from lower values in the back-water part. A similar relationship is visible for heavy metals. Referring to the ecotoxicological criteria, it can be stated that bottom sediments from the Sulejów Reservoir collected in 2018 are not toxicologically contaminated in terms of cadmium, lead and chromium content.