Hydrocarbon composition and distribution in a coastal region under influence of oil production in northeast Brazil

Waters and sediments from the Potiguar Basin (NE Brazilian coast) were investigated for the presence and nature of polycyclic aromatic hydrocarbons (PAH) and aliphatic hydrocarbons. The region receives treated produced waters through a submarine outfall system serving the industrial district. The total dispersed/dissolved concentrations in the water column ranged from 10-50 ng L⁻¹ for ∑16PAH and 5-10 μg L⁻¹ for total aliphatic hydrocarbons. In the sediments, hydrocarbon concentrations were low (0.5-10 ng g⁻¹for ∑16PAH and 0.01-5.0 μg g⁻¹ for total aliphatic hydrocarbons) and were consistent with the low organic carbon content of the local sandy sediments. These data indicate little and/or absence of anthropogenic influence on hydrocarbon distribution in water and sediment. Therefore, the measured values may be taken as background values for the region and can be used as future reference following new developments of the petroleum industry in the Potiguar Basin.     

Regimes of magma recharge and their control on the eruptive behaviour during the period 2001–2005 at Mt. Etna volcano

Mount Etna volcano (Italy) during the period 2001–2005 has undergone a period of intense eruptive activity marked by three large eruptions (2001, 2002–2003 and 2004–2005). These eruptions encompassed diverse eruptive styles and regimes: from intensely explosive, during 2001 and 2002–2003 eruptions, to exclusively effusive in the 2004–2005 event. In this work, we put forward the idea that these three eruptions are the response of the progressive arrival into the uppermost segment of the open-conduit system of a new magma, which was geochemically distinct in terms of trace element and Sr–Nd–Pb isotope signature from the products previously emitted by the Etnean volcano. The magma migrated upwards mainly through a peripheral tectonic system, which can be considered as eccentric in spite of its relative proximity to the main system. The ingress of the new magma and its gradual displacement from the eccentric system into the uppermost sector of the open-conduit gave rise to different eruptive behaviours. At the beginning, the ascent of the undegassed magma, able to exsolve a gas phase at depth, and its interaction with closed-system magma reservoirs less than 10 km deep gave rise to the explosive events of 2001 and 2002–2003. Later, when the same magma entered into the open-conduit system, it took part in the steady-state degassing and partially lost its volatile load, leading to a totally effusive eruption during the 2004–2005 event. One further consideration highlighted here is that in 2001–2005, migration of the feeding axis from an eccentric and peripheral position towards the main open-conduit has led to the development of a new vent (South East Crater 2) located at the eastern base of the South East Crater through which most of the subsequent Etnean activity occurred.     

Growth pattern and changes in abundance of the endangered bat star Asterina stellifera

The sea star Asterina stellifera has declined during the last decade and is currently abundant only in the southern limit of its former range. We surveyed this population over 5 years to model individual growth and explore the relationship of changes in local abundance with variation in environmental factors and the reproductive status of individuals. Our results show that A. stellifera is a species with slow growth and a relatively long lifespan. Contrary to expectations for temperate species, growth rates were fairly constant through the year and therefore models including seasonal oscillations were inappropriate. The abundance of this species increased significantly from early spring to early summer, likely due to augmented activity and small‐scale aggregation during the reproductive season that affected our estimates of abundance. No significant recruitment occurred during the 5 years studied. The lack of recruitment during long periods and the slow individual growth rates make A. stellifera particularly vulnerable to local extinction. This study was performed prior to the arrival in the study area of the invasive kelp Undaria pinnatifida and side‐gilled sea slug Pleurobranchaea maculata, species that threaten the community structure where A. stellifera lives. Therefore, the information reported here will be essential to assessing the impacts of these exotic species on this sea star population.     

MarcoPolo-R near earth asteroid sample return mission

MarcoPolo-R is a sample return mission to a primitive Near-Earth Asteroid (NEA) proposed in collaboration with NASA. It will rendezvous with a primitive NEA, scientifically characterize it at multiple scales, and return a unique sample to Earth unaltered by the atmospheric entry process or terrestrial weathering. MarcoPolo-R will return bulk samples (up to 2?kg) from an organic-rich binary asteroid to Earth for laboratory analyses, allowing us to: explore the origin of planetary materials and initial stages of habitable planet formation; identify and characterize the organics and volatiles in a primitive asteroid; understand the unique geomorphology, dynamics and evolution of a binary NEA. This project is based on the previous Marco Polo mission study, which was selected for the Assessment Phase of the first round of Cosmic Vision. Its scientific rationale was highly ranked by ESA committees and it was not selected only because the estimated cost was higher than the allotted amount for an M class mission. The cost of MarcoPolo-R will be reduced to within the ESA medium mission budget by collaboration with APL (John Hopkins University) and JPL in the NASA program for coordination with ESA’s Cosmic Vision Call. The baseline target is a binary asteroid (175706) 1996 FG3, which offers a very efficient operational and technical mission profile. A binary target also provides enhanced science return. The choice of this target will allow new investigations to be performed more easily than at a single object, and also enables investigations of the fascinating geology and geophysics of asteroids that are impossible at a single object. Several launch windows have been identified in the time-span 2020–2024. A number of other possible primitive single targets of high scientific interest have been identified covering a wide range of possible launch dates. The baseline mission scenario of MarcoPolo-R to 1996 FG3 is as follows: a single primary spacecraft provided by ESA, carrying the Earth Re-entry Capsule, sample acquisition and transfer system provided by NASA, will be launched by a Soyuz-Fregat rocket from Kourou into GTO and using two space segment stages. Two similar missions with two launch windows, in 2021 and 2022 and for both sample return in 2029 (with mission duration of 7 and 8?years), have been defined. Earlier or later launches, in 2020 or 2024, also offer good opportunities. All manoeuvres are carried out by a chemical propulsion system. MarcoPolo-R takes advantage of three industrial studies completed as part of the previous Marco Polo mission (see ESA/SRE (2009)3, Marco Polo Yellow Book) and of the expertise of the consortium led by Dr. A.F. Cheng (PI of the NASA NEAR Shoemaker mission) of the JHU-APL, including JPL, NASA ARC, NASA LaRC, and MIT.     

Biodiversity,ecological structure,and change in the sponge community of different geomorphological zones of the barrier fore reef at Carrie Bow Cay,Belize

Changes in the relative abundance of benthic groups on the barrier fore reef at Carrie Bow Cay, Belize, point to a significant reduction of corals and an expansion of the sponge community in 1995–2009. Fifty‐one species are now present in the four geomorphological zones of this reef: the low‐relief spur‐and‐groove zone, the inner reef slope, the outer ridge, and the fore‐reef slope (to a depth of 30 m). Five species are new additions to the sponge fauna reported for Belize, and six species account for 42.6% of the total assemblage: Niphates erecta (9.60%), Aiolochroia crassa (8.8%), Niphates digitalis (6.9%), Callyspongia plicifera (6.63%), Aplysina archeri (5.37%) and Xestospongia muta (5.37%). Species richness, average density, diversity and evenness indexes are statistically similar in these four zones but some species appear to be more dominant in certain areas. In the same 30 years, coral cover has decreased by more than 90%, while the octocoral cover has greatly increased (by as much as 10‐fold in the low‐relief spur‐and‐groove zone). Thus the Carrie Bow fore reef appears to be undergoing a transition from coral dominance in the late 1970s to algae dominance today, with other benthic groups such as sponges and octocorals showing signs of gradual recovery.     

Spring–summer cycling of DOC, DON and inorganic N in a highly seasonal system encompassing the Northeast Water Polynya, 1993

Dissolved organic nitrogen (DON), dissolved organic carbon (DOC) and inorganic nutrient concentrations were determined in samples from an area encompassing the Northeast Water Polynya from June to August 1993. In June, still ice-covered polynya area surface waters (PySW) had significantly higher (p<0.05) DOC concentrations (110 μM, n=68) than surface water outside the polynya area (96 μM, n=6). Melting ice and ice algae are suggested as DOC sources. DOC concentrations found in this study are consistent with other studies showing higher DOC concentrations in the Arctic than in other ocean areas. As the productive season progressed, DOC concentrations in Polynya surface water (PySW) decreased (p<0.05) from 110 to 105 μM, while DON concentrations increased (p<0.05) from 5.6 to 6.1 μM, causing a significant decrease (p<0.05) in the C : N ratios of DOM from spring (C : N ratio 20) to summer (C : N ratio 17). We found a significant (p<0.05) decrease in the DOM C : N ratio in all water masses within the polynya area as the productive season progressed. DON was the largest fraction of total dissolved nitrogen (TDN) in PySW and surface waters outside the polynya area. TDN was calculated as the sum of DON, nitrate, nitrite and ammonium concentrations. DON increased (p<0.05) from 62% to 73% of TDN in PySW from spring to summer, a result of increasing DON concentrations and decreasing inorganic nitrogen concentrations over the productive season. The seasonal accumulation of DON and the corresponding decrease in nitrate concentrations in waters with primary production indicate that it is important to take the DON pool into account when estimating export production from nitrate concentration decreases in surface waters. PySW TDN concentrations decreased (p<0.05) from 9.1 (n=61) to 8.6 μM (n=60) from spring (May 25 through June 19) to summer (July 1 through July 27). The seasonal decrease in surface water TDN concentrations corresponded to increases in TDN concentrations in deeper water masses within the Polynya. Most of the TDN increase in deep water was in the form of DON. A possible explanation is that PON was dissolved (partially remineralized) in the water column at mid depths, causing increases in the DON concentration. Transfer of N from PySW (with a short residence time in the polynya area) to Polynya Intermediate Water and deep waters of the Norske and Westwind Trough with multi-year residence times keeps N from leaving the polynya area. In spring, nutrients from degradation of OM in PyIW could support primary production. The role of PyIW as an OM trap could be important in supporting primary production in the polynya area.     

Behaviour of Instrumented Hollow Auger Pile Groups in Sandy Soil

Geotechnical and Geological Engineering - Hollow auger piles are a new solution technique being used more often in recent years as a foundation for buildings of 15 floors or less in the coastal...     

Linking soil water balance with flood spatial arrangement in an extremely flat landscape

In areas with very mild relief, water drains in a disordered way due to the lack of a developed drainage network, as it occurs in extremely flat sedimentary regions like the Argentine Pampas. The study analysed the flood spatial arrangements in 2014 by calculating landscape metrics and relating them to soil water balance. The study area is located at Del Azul creek lower basin (Pampa Ecoregion, Argentina). Daily soil water balances were obtained, and seven landscape metrics were calculated in 15 windows in five LandSat images, all along 2014, to explore the relationship between hydrological scenarios and spatial pattern summarized with principal component analysis. Water excess concentrated in winter (June and August); deficits were in late spring and summer (January and November), whereas the beginning of autumn (March) was an intermediate situation. Principal component 1 (44.7%) reflected area and shape metrics and correlated positively with water table level; principal component 2 (32.3%) summarized aggregation ones and was negatively associated with accumulated water excesses or deficits in previous 30 days and useful reserve. Both exhibited possible threshold-driven behaviour. Internal heterogeneity between NW and SE zones within the study area coincided with the existence of ancient alluvial fans. The results highlight the peculiarities of the flood spatial patterns in regions with very mild relief, where landforms usually determine water flows.     

Detrital Cr-spinel in the Šambron–Kamenica Zone (Slovakia): evidence for an ocean-spreading zone in the Northern Vardar suture?

The Šambron–Kamenica Zone is situated on the northern margin of the Levočské vrchy mountains and Šarišskà vrchovina Highland, where the Central Carpathian Paleogene joins the Pieniny Klippen Belt. Sandstone outcrops in this area. From Cretaceous to Late Oligocene in age, these sediments suggest transport directions from S and SE. The heavy mineral assemblages of this sandstone include Cr-spinel grains, mainly displaying types II and III alpine-peridotite affinities, and are representative of Ocean Island Basalt volcanism. A sample from Upper Eocene sediments at Vit’az shows a clear change in Cr-spinel composition, which turns out to have types I and II peridotite affinities, and to derive from arc and Middle Ocean Ridge Basalt volcanism, with sediment transport directions from SW and WSW. These data indicate major variations in the Upper Eocene tectonic setting, giving constraints to paleogeographic reconstruction of the Slovak Central Carpathians.     

Biotic effects of environmental catastrophes at the end of the Cretaceous and early Tertiary: Guembelitria and Heterohelix blooms

In this study we report similar biotic response patterns in planktic foraminiferal assemblages, whether in association with volcanism, impacts or climate change at the end of the Cretaceous and early Tertiary. During and after each type of catastrophe two groups dominate high stress assemblages: (1) the small Guembelitria species, which are interpreted as having thrived in eutrophic surface waters where other species rarely survived; and (2) the low oxygen tolerant small Heterohelix species, which thrived at times of an expanding oxygen minimum zone associated with high nutrients and a stratified water column. The ecosystem collapse appears to be primarily the result of high macro- and micronutrient influx (from impacts, volcanism and erosion) leading to eutrophication and phytoplankton blooms (i.e., primary producers) that result in toxic conditions for foraminifera. Once nutrients decrease due to consumption by phytoplankton, the first opportunistic foraminifera, the Guembelitria, appear and graze on phytoplankton, rapidly reproduce (heterochronic acceleration) and increase populations exponentially. With nutrient depletion Guembelitria populations rapidly decrease leading to ecologic niches for other generalists and ecosystem recovery. Small low O₂ tolerant heterohelicid populations mark this second stage, followed by small trochospiral and planispiral species. With further environmental recovery, increasing competition, niche development, and restoration of a well-stratified watermass, oligotrophic conditions are restored opening habitats for large, highly specialized species and a return to normal diverse assemblages. Such highly stressed ecological successions are observed in association with mantle plume volcanism in the Indian Ocean, Andean volcanism in Argentina and shallow inland seas in Egypt and Madagascar during the late Maastrichtian, the K-T impact, volcanism during the early Danian, and intense upwelling and climate extremes. We present a simple model to explain the ecological succession and recovery phases that follow major biotic perturbations.