Mariner Elements Research Articles

The Abrasive Wear Resistance of Coatings Manufactured on High-Strength Low-Alloy (HSLA) Offshore Steel in Wet Welding Conditions

Some marine and offshore structure elements exploited in the water cannot be brought to the surface of the water as this will generate high costs, and for this reason, they require in-situ repairs. One of the repair techniques used in underwater pad welding conditions is a wet welding method. This paper presents an investigation of the abrasive wear resistance of coatings made in wet welding conditions with the use of two grades of covered electrodes—an electrode for underwater welding and a commercial general use electrode. Both electrodes were also used for manufacturing coatings in the air, which has been also tested. The Vickers HV10 hardness measurements are performed to demonstrate the correlation in abrasive wear resistance and the hardness of each specimen. The microscopic testing was performed. For both filler materials, the coatings prepared in a water environment are characterized by higher resistance to metal–mineral abrasion than coatings prepared in an air environment—0.61 vs. 0.44 for commercial usage electrode and 0.67 vs. 0.60 for underwater welding. We also proved that in the water, the abrasive wear was greater for specimens welded by the general use electrode, which results in a higher hardness of the layer surface. In the air welding conditions, the layer welded by the electrode for use in the water was characterized by a lower hardness and higher resistance to metal–mineral abrasion. The microstructure of the prepared layers is different for both the environment and both electrodes, which results in abrasive wear resistance.

Complex Evolutionary History of Mboumar, a Mariner Element Widely Represented in Ant Genomes

Mboumar-9 is an active mariner-transposable element previously isolated in the ant Messor bouvieri. In this work, a mariner-like element, Mboumar, isolated from 22 species of ants, is analyzed. These species belong to nine different subfamilies, including Leptanillinae, the most primitive ant subfamily, and Myrmicinae and Formicidae, the most derived ones. Consequently, Mboumar-like elements seem to be well-represented in ant genomes. The phylogenetic tree drawn for mariner elements is highly inconsistent with the phylogeny of host ants, with almost identical elements found in clearly distant species and, on the contrary, more variable elements in closely related species. The inconsistency between the two phylogenetic trees indicates that these transposable elements have evolved independently from the speciation events of the ants that host them. Besides, we found closer genetic relationships among elements than among their host ants. We also found potential coding copies with an uninterrupted open reading frame of 345 aa in 11 species. The putative transposase codified by them showed a high sequence identity with the active Mboumar-9 transposase. The results of selection tests suggest the intervention of purifying selection in the evolution of these elements. Overall, our study suggests a complex evolutionary history of the Mboumar-like mariner in ants, with important participation of horizontal transfer events. We also suggest that the evolutionary dynamics of Mboumar-like elements can be influenced by the genetic system of their host ants, which are eusocial insects with a haplodiploid genetic system.

Homology-Free Detection of Transposable Elements Unveils Their Dynamics in Three Ecologically Distinct Rhodnius Species

Transposable elements (TEs) are widely distributed repetitive sequences in the genomes across the tree of life, and represent an important source of genetic variability. Their distribution among genomes is specific to each lineage. A phenomenon associated with this feature is the sudden expansion of one or several TE families, called bursts of transposition. We previously proposed that bursts of the Mariner family (DNA transposons) contributed to the speciation of Rhodnius prolixus Stål, 1859. This hypothesis motivated us to study two additional species of the R. prolixus complex: Rhodnius montenegrensis da Rosa et al., 2012 and Rhodnius marabaensis Souza et al., 2016, together with a new, de novo annotation of the R. prolixus repeatome using unassembled short reads. Our analysis reveals that the total amount of TEs present in Rhodnius genomes (19% to 23.5%) is three to four times higher than that expected based on the original quantifications performed for the original genome description of R. prolixus. We confirm here that the repeatome of the three species is dominated by Class II elements of the superfamily Tc1-Mariner, as well as members of the LINE order (Class I). In addition to R. prolixus, we also identified a recent burst of transposition of the Mariner family in R. montenegrensis and R. marabaensis, suggesting that this phenomenon may not be exclusive to R. prolixus. Rather, we hypothesize that whilst the expansion of Mariner elements may have contributed to the diversification of the R. prolixus-R. robustus species complex, the distinct ecological characteristics of these new species did not drive the general evolutionary trajectories of these TEs.

Relationship between indoor and outdoor size-fractionated particulate matter in urban microenvironments: Levels, chemical composition and sources

Exposure to particulate matter (PM) has been associated with adverse health outcomes, particularly in susceptible population groups such as children. This study aims to characterise children's exposure to PM and its chemical constituents. Size-segregated aerosol samples (PM0.25, PM0.25–0.5, PM0.5–1.0, PM1.0–2.5 and PM2.5–10) were collected in the indoor and outdoor of homes and schools located in Lisbon (Portugal). Organic and elemental carbon (OC and EC) were determined by a thermo-optical method, whereas major and trace elements were analysed by X-Ray Fluorescence. In school, the children were exposed to higher PM concentrations than in home, which might be associated not only to the elevated human occupancy but also to outdoor infiltration. The pattern of PM mass size distribution was dependent on the location (home vs. school and indoor vs. outdoor). The presence of EC in PM0.25 and OC in PM0.25–0.5 was linked to traffic exhaust emissions. OC and EC in PM2.5–10 may be explained by their adhesion to the surface of coarser particles. Generally, the concentrations of mineral and marine elements increased with increasing PM size, while for anthropogenic elements happened the opposite. In schools, the concentrations of mineral matter, anthropogenic elements and marine aerosol were higher than in homes. High mineral matter concentrations found in schools were related to the close proximity to busy roads and elevated human occupancy. Overall, the results suggest that exposure to PM is relevant and highlights the need for strategies that provide healthier indoor environments, principally in schools.

Very Deep Neural Networks for Extracting MITE Families Features and Classifying them based on DNA Scalograms

DNA sequencing has recently generated a very large volume of data in digital format. These data can be compressed, processed and classified only by using automatic tools which have been employed in biological experiments. In this work, we are interested in the classification of particular regions in C. Elegans Genome, a recently described group of transposable elements (TE) called Miniature Inverted-repeat Transposable Elements (MITEs). We particularly focus on the four MITE families (Cele1, Cele2, Cele14, and Cele42). These elements have distinct chromosomal distribution patterns and specific number conserved on the six autosomes of C. Elegans. Thus, it is necessary to define specific chromosomal domains and the potential relationship between MITEs and Tc / mariner elements, which makes it difficult to determine the similarities between MITES and TC classes. To solve this problem and more precisely to identify these TEs, these data are classified and compressed, in this study, using an efficient classifier model. The application of this model consists of four steps. First, the DNA sequence are mapped in a scalogram’s form. Second, the characteristic motifs are extracted in order to obtain a genomic signature. Third, MITE database is randomly divided into two data sets: 70% for training and 30%for tests. Finally, these scalograms are classified using Transfer Learning Approach based on pre-trained models like VGGNet. The introduced model is efficient as it achieved the highest accuracy rates thanks to the recognition of the correct characteristic patterns and the overall accuracy rate reached 97.11% for these TEs samples classification. Our approach allowed also classifying and identifying the MITES Classes compared to the TC class despite their strong similarity. By extracting the features and the characteristic patterns, the volume of massive data was considerably reduced.

The Aegean Imaginarium: Selected Stereotypes and Associations Connected with the Aegean Sea and Its Islands in Roman Literature in the Period of the Principate

This article is devoted to the rarely addressed problem of Roman stereotypes and associations connected with the Aegean Sea and its islands in the works of Roman authors in the first three centuries of the Empire. The image of the Aegean islands in the Roman literature was somewhat incongruously compressed into contradictory visions: islands of plenty, desolate prisons, always located far from Italy, surrounded by the terrifying marine element. The positive associations stemmed from previous cultural contacts between the Aegean and Rome: the Romans admired the supposedly more developed Greek civilisation (their awe sometimes underpinned by ostensible disparagement), whereas their elites enjoyed their Aegean tours and reminisced about past glories of Rhodes and Athens. The negative associations came from the islands’desolation and insignificance; the imperial authors, associating the Aegean islets with exile spots, borrowed such motifs from classical and Hellenistic Greek predecessors. The Aegean Sea, ever-present in the rich Greek mythical imaginarium, inspired writers interested in myth and folklore; other writers associated islands with excellent crops and products, renowned and valued across the Empire.

Palynostratigraphy of dinosaur bone-bearing deposits from the Upper Cretaceous of Western Bulgaria

Palynological investigation of the Vrabchov dol locality (Western Bulgaria) which recently yielded fragmentary dinosaur bones attributed to the clade Titanosauria, reveals well-preserved sporomorph assemblages dominated by angiosperm pollen from the Normapolles group, spores and rare gymnosperms. The age assessment of the studied sequence is based on the diagnostic Normapolles species, such as Oculopollis orbicularis Góczán, 1964, Oculopollis zaklinskaiae Góczán, 1964, Krutzschipollis spatiosus Góczán in Góczán et al., 1967 and Krutzschipollis crassus (Góczán, 1964) Góczán in Góczán et al., 1967. The concurrent presence of these pollen species suggests a late Santonian–early Campanian age for the succession. The sporomorph association is encountered in a palynofacies dominated by continental elements, including translucent phytoclasts (tissues, wood remains and plant cuticles). The sedimentary succession shows no evidence of marine elements and a very low proportion of AOM that attests to deposition within a lagoonal to foreshore marine environment, with high continental input and short transportation. The vegetation in the studied area was primarily composed of a range of Normapolles-producing angiosperms and secondarily of pteridophyte spore-producing plants. Gymnosperms were rare. Such a vegetation pattern reflects a warm, seasonally dry climate during the late Santonian–earliest Campanian in the studied area. The dinosaurs inhabited a wet lowland area, probably rich in herbaceous plants.

Microbial Community Compositions and Geochemistry of Sediments with Increasing Distance to the Hydrothermal Vent Outlet in the Kairei Field

Microbial metabolisms in sediments play a pivotal role in marine element cycling. In hydrothermal sediments chemosynthetic microorganisms likely prevail, while in non-hydrothermally impacted sediment regimes microorganisms associated with organic matter decomposition are primarily recognized. To test how these microorganisms are distributed along the hitherto neglected transition zone influenced to different degrees by hydrothermal input we sampled four sediment sites: these were (i) near an active vent, (ii) the outer rim, and (iii) the inactive area of the Kairei hydrothermal field as well as (iv) sediments roughly 200 km south-east of the Kairei field. Chemistry and microbial community compositions were different at all sampling sites. Against expectations, the sediments near the active vent did not host typical chemosynthetic microorganisms and chemistry did not indicate current, extensive hydrothermal venting. Data from the outer rim area of the active Kairei field suggested microbially mediated saponite production and diffuse hydrothermal flow from below accompanied by increased metal concentrations. A steep redox gradient in the inactive Kairei field points towards significant redox driven processes resulting in dissolution of hydrothermal precipitates and intense metal mobilization. Local microorganisms were primarily Chloroflexi, Bacillales, Thermoplasmata, and Thaumarchaeota.

Stowaway miniature inverted repeat transposable elements are important agents driving recent genomic diversity in wild and cultivated carrot

BackgroundMiniature inverted repeat transposable elements (MITEs) are small non-autonomous DNA transposons that are ubiquitous in plant genomes, and are mobilised by their autonomous relatives. Stowaway MITEs are derived from and mobilised by elements from the mariner superfamily. Those elements constitute a significant portion of the carrot genome; however the variation caused by Daucus carota Stowaway MITEs (DcStos), their association with genes and their putative impact on genome evolution has not been comprehensively analysed.ResultsFourteen families of Stowaway elements DcStos occupy about 0.5% of the carrot genome. We systematically analysed 31 genomes of wild and cultivated Daucus carota, yielding 18.5 thousand copies of these elements, showing remarkable insertion site polymorphism. DcSto element demography differed based on the origin of the host populations, and corresponded with the four major groups of D. carota, wild European, wild Asian, eastern cultivated and western cultivated. The DcStos elements were associated with genes, and most frequently occurred in 5′ and 3′ untranslated regions (UTRs). Individual families differed in their propensity to reside in particular segments of genes. Most importantly, DcSto copies in the 2 kb regions up- and downstream of genes were more frequently associated with open reading frames encoding transcription factors, suggesting their possible functional impact. More than 1.5% of all DcSto insertion sites in different host genomes contained different copies in exactly the same position, indicating the existence of insertional hotspots. The DcSto7b family was much more polymorphic than the other families in cultivated carrot. A line of evidence pointed at its activity in the course of carrot domestication, and identified Dcmar1 as an active carrot mariner element and a possible source of the transposition machinery for DcSto7b.ConclusionStowaway MITEs have made a substantial contribution to the structural and functional variability of the carrot genome.

On the chemical nature of wet deposition over a major desiccated lake: Case study for Lake Urmia basin

Abstract One of the largest hyper-saline lakes in the world is Lake Urmia, which is in the northwest region of Iran. Lake Urmia has experienced extreme desiccation in recent years. This study was conducted to investigate possible impacts of aerosol emitted by Lake Urmia on rainwater properties. Rainwater samples were collected from September 2017 to September 2018 at 13 sites spanning different areas of the Lake Urmia basin. Samples were analysed for acidity/alkalinity (pH), electrical conductivity (EC), total suspended solids (TSS) and elemental composition (Na, Mg, K, Ca, Al, Fe, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, and Pb). The results reveal that rainwater around Lake Urmia is characterized by high concentrations of heavy metals and toxic elements (e.g., Fe, Al, Ni, Cu, Cr, Co, Ti), especially in the outer ring of the study region to the north. Chemical signatures of anthropogenic pollution were most evident at sites near populated and manufacturing centers. The average pH of rainwater was enhanced relative to other regions, with the lowest and highest values of the 13 sites being 7.7 and 8.6, respectively. Concentrations of marine elements (Na+, K+, Mg2+, Ca2+) decreased with increasing distance from Lake Urmia, suggestive of possible impacts of the lakebed's emission on rain composition via likely below-cloud scavenging. The area impacted by the marine aerosol emitted by Lake Urmia has a diameter of 30 to 40 km surrounding the shoreline. The results reveal a stronger signature of crustal species in the north owing to desiccated lakebed hotspots located in the north.

Riding the Wave: The SINE-Specific V Highly-Conserved Domain Spread into Mammalian Genomes Exploiting the Replication Burst of the MER6 DNA Transposon.

Transposable elements are widely distributed within genomes where they may significantly impact their evolution and cell functions. Short interspersed elements (SINEs) are non-autonomous, fast-evolving elements, but some of them carry a highly conserved domain (HCD), whose sequence remained substantially unchanged throughout the metazoan evolution. SINEs carrying the HCD called V are absent in amniote genomes, but V-like sequences were found within the miniature inverted-repeat transposable element (MITE) MER6 in Homo sapiens. In the present work, the genomic distribution and evolution of MER6 are investigated, in order to reconstruct the origin of human V domain and to envisage its possible functional role. The analysis of 85 tetrapod genomes revealed that MER6 and its variant MER6A are found in primates, while only the MER6A variant was found in bats and eulipotyphlans. These MITEs appeared no longer active, in line with literature data on mammalian DNA transposons. Moreover, they appeared to have originated from a Mariner element found in turtles and from a V-SINE from bony fishes. MER6 insertions were found within genes and conserved in mRNAs: in line with previous hypothesis on functional role of HCDs, the MER6 V domain may be important for cell function also in mammals.

Marine and freshwater taxa: some numerical trends

Most of the freshwater fauna originates from ancient or recent marine ancestors. In this study, we considered only completely aquatic non-parasitic animals, counting 25 phyla, 77 classes, 363 orders for a total that should include 236,070 species. We divided these taxa into three categories: exclusively marine, marine and freshwater, and exclusively freshwater. By doing so, we obtained three distribution curves which could reflect the marine species’ mode of invasion into continental waters. The lack of planktonic stages in the benthic fauna of inland waters, in addition to what we know about the effects of the impoundment of epicontinental seas following marine regressions, lead us to think that the main invasion mode into inland waters is more linked to the sea level fluctuations of the past than to slow and “voluntary” ascents of rivers by marine elements.

Syn‐rift sequence development in a fault‐controlled embayment (Early Permian Irwin River Coal Measures, Northern Perth Basin, Western Australia)

AbstractStratigraphic patterns and sequence development in tectonically active extensional basins remain poorly documented in comparison with passive‐margin settings. Rift basin fills are generally characterized by coarsening‐upward trends in response to the rapid creation of accommodation by extensional faulting, and the progressive filling of graben during more quiescent periods. The Early Permian Irwin River Coal Measures in the Northern Perth Basin (Western Australia) record a complex stratigraphic arrangement of conglomerate, sandstone, mudstone and coal, and have been attributed to delta plain depositional environments that developed in a cool–temperate climatic setting during syn‐rift activity. Sedimentary analysis of outcrop and core data from the fault‐bounded Irwin Terrace is used to distinguish nine facies associations reflecting deposition in braided rivers, fixed‐anastomosed channel belts, tide‐influenced coastal environments and storm‐affected distal bays. The broader depositional system is interpreted as a morphologically asymmetrical tide‐dominated embayment with a fluvial and wave influence. The stratigraphic architecture of the Irwin River Coal Measures was strongly influenced by the evolving rift basin margin. Fault reactivation of the major basin‐bounding Darling Fault in the early syn‐rift phase caused footwall uplift and the inception of transverse palaeo‐valleys occupied by braided fluvial systems. Fault block subsidence during the subsequent balanced, backstepping and drowning phases resulted in a dominantly retrogradational stacking pattern indicating progressive flooding of marginal‐marine areas and culminating in deposition of distal marine elements. In the active rift basin, it is proposed that preservation of a shallow‐marine syn‐rift sequence was promoted by the geomorphological confinement of the embayed system increasing tidal current acceleration and hampering transgressive ravinement. The proposed sequence model demonstrates that transgressive successions can develop in the early syn‐rift phase in response to footwall uplift and tectonic subsidence. The syn‐rift sequence recording the filling of an embayment on a rift basin margin may be applied in similar tectonic and/or depositional contexts worldwide.

Mountains‐to‐the‐sea conservation: An island perspective

Abstract Island nations such as New Zealand provide valuable insights into conservation challenges posed by strongly connected and recently developed or exploited freshwater and marine ecosystems. The narrow land mass, high rainfall, and steep terrain of New Zealand, like many other island nations, mean that land‐based stressors are rapidly transferred to freshwater habitats and propagated downstream to coastal environments via short, fast‐flowing river systems. Freshwater and marine environments are linked through faunal life histories; for example, diadromous fishes, many of which are considered threatened or at risk of extinction, and require cross‐ecosystem conservation to ensure survival of critical life stages and persistence of source populations. Recent invasions of marine and freshwater environments by non‐indigenous species reveal rapid impacts on a naïve biota and highlight conservation conundrums caused by management aimed at enhancing native biodiversity by improving habitat connectivity. Understanding and managing interconnected freshwater and marine ecosystems is a key concept for local indigenous communities, and highlights socio‐cultural connectivity and sustainable local harvesting of traditional resources as key elements of contemporary marine and freshwater conservation planning in New Zealand.

An institutional framework for addressing marine genetic resources under the proposed treaty for marine biodiversity in areas beyond national jurisdiction

In December 2017, the United Nations General Assembly decided to convene an intergovernmental conference to elaborate an international legally binding instrument on marine biodiversity in areas beyond national jurisdiction. This legally binding instrument would address four elements, namely marine protected areas, marine genetic resources, environmental impact assessments and capacity building and technology transfer. One of the indicators for the success of the legally binding instrument will be an institutional mechanism that is both effective and that can co-exist with existing mechanisms. There is already a proposal for an institutional mechanism under the implementing agreement. However, the proposed institutional mechanism was developed largely with marine protected areas in mind. The purpose of this article is to determine whether this proposed mechanism could work also for the marine genetic resources element of the proposed treaty. This is necessitated by the fact that the marine genetic resources element of the proposed treaty is far more complex and raises issues that are more intractable.

New marine reptile fossils from the Oxfordian (Late Jurassic) of Greenland

AbstractKnowledge about marine reptile diversity and disparity during the Late Jurassic is increasing. This contribution describes marine reptile skeletal elements (ichthyosaur and plesiosaur) from Kingofjeld mountain in NE Greenland. The assemblage is early Late Oxfordian (Late Jurassic) in age, and consists ofc. 100 disarticulated skeletal elements. The location is of biogeographic importance as it was at the time situated between the Boreal realm and the Tethys Sea and is promising in terms of future prospecting.

Decimeter-scale mapping of carbonate-controlled trace element distribution in Neoarchean cuspate stromatolites

Ancient stromatolites can provide key insights into the early evolution of life on Earth. Neoarchean fenestrate stromatolites from the ∼2520 Ma Upper Nauga Formation (Transvaal Supergroup, South Africa) preserve cuspate morphologies. They possess clearly delineated support and drape structures interpreted as dolomitized microbial mat material. Petrographic observations show that the biogenic structures are composed of planar-s to non-planar ferroan dolomite, encased in ferroan calcite, including herringbone calcite textures. The cuspate stromatolites were analyzed using Synchrotron Rapid Scanning X-Ray Fluorescence (SRS-XRF) and more conventional techniques to determine: (i) whether element distributions could be distinguished in ancient stromatolites at both cm to dm scales, (ii) whether element distributions show variation between biogenic and abiogenic textures, and (iii) the sample’s paragenesis. The distributions of Ca, Fe, Mn, Pb, Cu, As, Br, Al, Si, P, and S directly correspond to dolomitized stromatolitic structures and show trace element distributions are principally controlled by calcite and dolomite occurrence. Dolomite formation was mainly driven by seawater-derived fluids given the high concentrations of Fe and retention of marine shale-normalized rare earth element and yttrium (REY SN ) patterns, however the spatial association of dolomite to stromatolite structures may reflect microbially-influenced mineral nucleation. Given the complexity of this sample’s paragenetic evolution, trace metal distributions cannot be conclusively tied to specific metabolic pathways, bioaccumulation or passive binding, however, the results show SRS-XRF can be used for quantifiable, spatial, in-situ investigation of ancient microbialites.

Insights into the Regulation of Algal Proteins and Bioactive Peptides Using Proteomic and Transcriptomic Approaches.

Oceans abound in resources of various kinds for R&D and for commercial applications. Monitoring and bioprospecting allow the identification of an increasing number of key natural resources. Macroalgae are essential elements of marine ecosystems as well as a natural resource influenced by dynamic environmental factors. They are not only nutritionally attractive but have also demonstrated potential health benefits such as antioxidant, antihypertensive, and anti-inflammatory activities. Several bioactive peptides have been observed following enzymatic hydrolysis of macroalgal proteins. In addition, significant differences in protein bioactivities and peptide extracts of wild and cultivated macroalgae have been highlighted, but the metabolic pathways giving rise to these bioactive molecules remain largely elusive. Surprisingly, the biochemistry that underlies the environmental stress tolerance of macroalgae has not been well investigated and remains poorly understood. Proteomic and functional genomic approaches based on identifying precursor proteins and bioactive peptides of macroalgae through integrated multi-omics analysis can give insights into their regulation as influenced by abiotic factors. These strategies allow evaluating the proteomics profile of regulation of macroalgae in response to different growth conditions as well as establishing a comparative transcriptome profiling targeting structural protein-coding genes. Elucidation of biochemical pathways in macroalgae could provide an innovative means of enhancing the protein quality of edible macroalgae. This could be ultimately viewed as a powerful way to drive the development of a tailored production and extraction of high value molecules. This review provides an overview of algal proteins and bioactive peptide characterization using proteomics and transcriptomic analyses.

Late Aptian (Early Cretaceous) dry–wet cycles and their effects on vegetation in the South Atlantic: Palynological evidence

The Cretaceous is generally conceived as one of the warmest geological periods in Earth history. The link between climate and plant distribution is here highlighted on the basis of palynological analyses. An upper Aptian well section from the Sergipe Basin in northeastern Brazil documents four cycles of dry–wet oscillations, based on palynological evidence. The cycles show a general trend of acceleration of the hydrological cycle. Dry periods are recorded mainly at the base of the section, with changes to more humid periods upwards. The dry periods are characterized by high to very high abundance of Classopollis classoides pollen grains. Already in the wet periods a conspicuous change in vegetation is recorded, with an increase in fern spores and upland flora, in particular Araucariacites australis pollen grains. The replacement of Classopollis by Araucariacites and ferns reflects a change from dry to wet conditions. The first dry–wet cycle (DWC-1) is recorded in the dominantly non-marine phase. At the base of this first cycle, intensive growth of anhydrite nodules is recorded. However, in beds overlying the evaporites, there is a conspicuous increase in flora associated with humid conditions (ferns and upland flora). DWC-2 starts with a pronounced peak of dinoflagellate cysts, which decrease abruptly accompanied by an increase in xerophytic flora (e.g., Classopollis classoides, Equisetosporites spp.). The abundance of xerophytic flora decreases upwards to give room for high abundances of fern spores, upland flora (e.g., Araucariacites australis, Cicatricosisporites spp.) and, in particular, dinoflagellate cysts. DWC-3 starts with a short interval containing a moderate abundance of xerophytes and a conspicuous wet flora and marine elements. With rising humidity, fern spore diversity also increased, suggesting that humidity was an important factor for the increase in diversity of this group. DWC-4 records minor peaks of xerophytic flora and a dominance of fern spores and upland flora. The progressive change in flora may be the result of displacement of the Intertropical Convergence Zone (ITCZ) and a relative sea-level rise.

Determination of water level design for an estuarine city

Based on the extreme value theory, self–affinity, and scale invariance, we studied the temporal and spatial relationship and the variation of water level and established a model of Gumbel–Pareto distribution for designed flood calculation. The model includes the previous extreme value models, the over–threshold data, and the fractal features shared by previous extreme value models. The model was simplified into a logarithmic normal distribution and a Pareto distribution for specific parameter values, and was used to calculate the designed flood values for the Shanghai Wusong Station in 100– and 1 000–year return periods. The calculated results show that the value of the designed flood height calculated in the Gumbel–Pareto distribution is between those in the Gumbel and Pearson–III distributions. The designed flood values in the 100– and 1 000–year return periods of the model were 0.03% and 0.11% lower, respectively, than the Gumbel distribution and 0.06% and 1.54% higher, respectively, than the Pearson–III distribution. Compared to the traditional model based solely on extreme probability, the Gumbel–Pareto distribution model could better describe the probabilistic characteristics of extreme marine elements and better use the data.