Electron spin resonance optical dating of marine,estuarine, and aeolian sediments in Florida,USA

For the first time, electron spin resonance optical dating (ESROD) has been conducted on littorally transported and aeolian siliciclastic sediments in Florida. ESROD utilizes light-sensitive radiation-sensitive defects at silicon sites that have been replaced by aluminum and titanium atoms to give rise to a time-dependant signal. These defects saturate at higher levels of radiation dose, compared to optically stimulated luminescence, and therefore extend the optical dating range back into the millions of years. Our results show that the Trail Ridge Sequence is a multi-depositional unit that began deposition around 2.2 Ma and continued until 6 ka. The Osceola Cape, of the Effingham Sequence, was deposited around 1.5 Ma, and the Chatham Sequence was a multi-depositional terrace with at least three events preserved.     

Australian ‘gayborhoods’ and ‘lesborhoods’: a new method for estimating the number and prevalence of adult gay men and lesbian women living in each Australian postcode

ABSTRACT

Gay men and lesbian women often demonstrate unique settlement patterns, forming what have been referred to as ‘gayborhoods’. This study sought to provide the first postcode-level estimates of population size and prevalence of gay and lesbian people in Australia. Data on same-gender-partnered households from the Australian Census were combined with information from six different surveys conducted from 2011 to 2017. We estimated that in 2016 there were 132,203 gay men (1.5% of adult males; 95% CI: 1.4–1.6) and 79,931 lesbian women (0.9% of adult females; 95% CI: 0.8–1.0) in Australia. While many postcodes were sparsely populated by gay and lesbian people (40.1% had prevalences of <0.1%), 24.6% were moderately populated (prevalences in the 50-95th percentile) and 2.7% were highly populated (95th percentile). By jurisdiction, the Australian Capital Territory had the highest prevalences of gay men (2.1%; 95% CI: 2.0–2.2) and lesbian women (1.5%; 95% CI: 1.4–1.6). Although the majority of highly populated postcodes were found in major cities (83.7%), some were also found in regional and remote area (16.3%). This method can be applied in other countries to enhance populate estimates. The accompanying dataset can be used to guide service delivery, conduct geographically contextualised research and develop policies relevant to gay men and lesbian women in Australia.     

Groundwater flow and contaminant transport modelling at an air weapons range

Numerical modelling was done at the Cold Lake Air Weapons Range, Canada, to test whether the dissolved RDX and nitrate detected in groundwater come from the same sources, and to predict whether contamination poses a threat to the surface water receptors near the site. Military live fire training activities may indeed pose a risk of contamination to groundwater resources, however field investigations on military bases are quite recent, and little information is available on the long-term behaviour of munition residues related contaminants. Very limited information was available about the contaminant source zones, which were assigned based on our knowledge of current training activities. The RDX plume was well represented with the model, but the heterogeneous distribution of nitrate concentrations was more difficult to reproduce. It was nonetheless determined that both contaminants originate from the same areas. According to the model, both contaminants should reach the nearby river, but concentrations in the river should remain very low if the source zone concentration does not change. Finally, the model allowed the recommendation of a new location for the main bombing target, which would offer added protection to the river and the lake into which it flows.     

打造过硬品牌以彰显地质公园在UNESCO世界级名录中的特殊地位——PPF理念(“过去—现在—将来”理念)

目前世界地质公园网络(GGN)共有90个成员,分布在27个国家和地区,尽管在这个网络建立过程中,联合国教科文组织起着关键作用,但在过去十多年里,其与地质公园的关系只能被定义为“特别支持”,眼下两者的关系应该在一个国际倡议或计划下被正式化,这将有利于进一步提高地质公园的管理、交流合作和资源利用.实现该目标,就要清晰地阐明地质公园核心的独有特色,使地质公园与联合国教科文组织已实施的计划形成互补,不会产生冲突或重叠.本文介绍的PPF理念将会是一个有效的方法,以此创建一个过硬的品牌,彰显地质公园在UNESCO世界级名录中的特殊地位.     

Estuarine resources use by juvenile Flagfin mojarra (Eucinostomus melanopterus) in an inverse tropical estuary (Sine Saloum,Senegal)

The Flagfin mojarra, Eucinostomus melanopterus, is a marine spawner whose young individuals are common in the Sine Saloum inverse estuary (Senegal). The species offers the opportunity to study both the use of the estuarine nursery resources and the impact of the particular environment of the inverse estuary on these resources. This will lead to a better understanding of the functioning of the nursery. We investigated the resources used by juvenile Flagfin mojarra by coupling stomach contents and stable isotopes methods.     

Reconstructing 4000 years of mass movement and tsunami history in a deep peri‐Alpine lake (Lake Geneva,France‐Switzerland)

The study of mass movements in lake sediments provides insights into past natural hazards at historic and prehistoric timescales. Sediments from the deep basin of Lake Geneva reveal a succession of six large‐scale (volumes of 22 × 10⁶ to 250 × 10⁶ m³) mass‐transport deposits, associated with five mass‐movement events within 2600 years (4000 cal bp to 563 ad ). The mass‐transport deposits result from: (i) lateral slope failures (mass‐transport deposit B at 3895 ± 225 cal bp and mass‐transport deposits A and C at 3683 ± 128 cal bp ); and (ii) Rhône delta collapses (mass‐transport deposits D to G dated at 2650 ± 150 cal bp , 2185 ± 85 cal bp , 1920 ± 120 cal bp and 563 ad , respectively). Mass‐transport deposits A and C were most probably triggered by an earthquake, whereas the Rhône delta collapses were likely to be due to sediment overload with a rockfall as the external trigger (mass‐transport deposit G, the Tauredunum event in 563 ad known from historical records), an earthquake (mass‐transport deposit E) or unknown external triggers (mass‐transport deposits D and F). Independent of their origin and trigger mechanisms, numerical simulations show that all of these recorded mass‐transport deposits are large enough to have generated at least metre‐scale tsunamis during mass movement initiation. Since the Tauredunum event in 563 ad , two small‐scale (volumes of 1 to 2 × 10⁶ m³) mass‐transport deposits (H and I) are present in the seismic record, both of which are associated with small lateral slope failures. Mass‐transport deposits H and I might be related to earthquakes in Lausanne/Geneva (possibly) 1322 ad and Aigle 1584 ad , respectively. The sedimentary record of the deep basin of Lake Geneva, in combination with the historical record, show that during the past 3695 years, at least six tsunamis were generated by mass movements, indicating that the tsunami hazard in the Lake Geneva region should not be neglected, although such events are not frequent with a recurrence time of 0·0016 yr^?1.     

226Ra and222Rn contents of Galapagos Rift hydrothermal waters —the importance of low-temperature interactions with crustal rocks

Hydrothermal waters collected by “Alvin” from the Galapagos Spreading Center are enriched in²²²Rn by factors of 50–200 over bottom waters. The²²⁶Ra in the same samples, however, is enriched by less than a factor of four over bottom waters. Enrichments of²²²Rn result primarily from α-recoil from rock surfaces while²²⁶Ra enrichments are dominantly produced by high-temperature alteration of cooling ridge volcanics. The abundances of both nuclides exhibit positive correlations with temperature. The data extrapolate to bottom water temperatures and compositions, demonstrating the importance of seawater mixing. Different vents, however, have different mixing lines, and vents with high²²²Rn have low²²⁶Ra. We propose these patterns result from variations in the extent of low-temperature crustal interaction with the hydrothermal fluids. Low-temperature crustal waters can maintain high steady state²²²Rn contents due to the α-recoil additions to the fluids. The²²⁶Ra, however, is strongly adsorbed at low-temperatures resulting in low concentrations of this nuclide in low-temperature crustal waters. Thus, physical mixing of a crustal water component with hydrothermal waters or variable crustal path lengths of the hydrothermal fluids can account for the variable mixing lines and²²²Rn/²²⁶Ra values of the hot springs.The²²²Rn/²²⁶Ra value appears to be a sensitive indicator of low-temperature crustal interaction. Values > 100 have experienced extensive crustal interaction and are indicative of diffuse hydrothermal flow. Values between 1 and 10 are indicative of primary hydrothermal fluids which have not experienced significant interaction with the crust. Values of²²²Rn/²²⁶Ra between 10³ and 10⁴ are indicative of interaction of the hydrothermal fluids with sediments. Such values are observed in water samples from the Galapagos hydrothermal mounds.