There is a relative lack of research, targeted models and tools to manage beaches in estuaries and bays (BEBs). Many estuaries and bays have been highly modified and urbanised, for example port developments and coastal revetments. This paper outlines the complications and opportunities for conserving and managing BEBs in modified estuaries. To do this, we focus on eight diverse case studies from North and South America, Asia, Europe, Africa and Australia combined with the broader global literature. Our key findings are as follows: (1) BEBs are diverse and exist under a great variety of tide and wave conditions that differentiate them from open-coast beaches; (2) BEBs often lack statutory protection and many have already been sacrificed to development; (3) BEBs lack specific management tools and are often managed using tools developed for open-coast beaches; and (4) BEBs have the potential to become important in “nature-based” management solutions. We set the future research agenda for BEBs, which should include broadening research to include greater diversity of BEBs than in the past, standardising monitoring techniques, including the development of global databases using citizen science and developing specific management tools for BEBs. We must recognise BEBs as unique coastal features and develop the required fundamental knowledge and tools to effectively manage them, so they can continue providing their unique ecosystem services.

The modern Nile delta developed in the Middle and Late Holocene, and at its most northern-central point is situated at the Burullus Lagoon, which is environmentally diverse, including salt marshes, mudflats, and sand plains, and separated from a sea by a sand barrier overtopped with high sand dunes. The lagoon has been fed since the Middle Holocene by the Sebennitic branch of the Nile and marine intrusions through the Bughaz inlet. A sediment core (BO-1) was collected at the northeastern shore of the lagoon and sampled at centennial scale resolution in order to reconstruct the development of the lagoon. The results show that an initial and limited lagoon had developed at the end of the Early Holocene, but after a dry period ca. 7.2 cal ka BP it has been progressively transformed into a marshy area, with occasional inflows of sea water. Lower water level and higher salinity of the Burullus Lagoon at 6.0–5.5 and 4.8–4.2 cal ka BP reflected droughts in the Nile catchment. Thereafter, the river reactivated in the Burullus Lagoon area, and since 2.8 cal ka BP was accompanied by occasional inflows of sea water. Since ca. 0.8 cal ka BP, increased fluvial activity occurred in this part of the Nile delta, which terminated after construction of the Aswan dams in the twentieth century.

Archaeological records of the Neolithic settlements on the eastern China coast between 35°N and 30°N, an area covering the abandoned Yellow River and the Yangtze River delta plains, reveal that Neolithic people moved from the Yellow River basin onto the northern coast for fishing, hunting and dry-land agriculture ~ 7000 yr ago. Marine transgression interrupted their activities on the low-lying (2–5 m in elevation) coastal wetlands between 6000 and 5000 yr ago, after which they reclaimed their land near the river mouths. Their migration routes on the southern Yangtze delta plain indicate another scenario: early Neolithic communities moved onto the plain for wet-rice cultivation. Despite relative sea-level rise from 7000 to 4000 yr ago, a large number of settlements were established on the lowlands between the eastern Chenier Ridges and the western Taihu Lake depression. The Chenier Ridges, with ~ 1.0 m higher topography than the adjacent coastal area, played a role in sheltering the Neolithic people. Subsequently, settlements waned considerably, possibly due to further marine inundation combined with cold climate. The present study shows that migration patterns of the Neolithic settlements are closely associated with a gradually rising sea level between 7000 and 4000 yr ago.

During the mid-Holocene the eastern Taihu area, on China's Yangtze delta plain, was populated by advanced late Neolithic cultures supported by intensive domesticated rice cultivation. This agricultural system collapsed around 4200 cal yr BP, with severe population decline, the end of the Liangzhu culture, and about half a millennium of very low-scale human activity in the area before the re-establishment of agricultural production. Microfossil analyses from six sedimentary sequences, supported by AMS 14C dating, has allowed reconstruction of mid-Holocene hydrological conditions and salinity changes which would have had a major influence on agricultural viability and cultural history in the coastal wetlands. These data, allied to existing stratigraphic and sea-level records, show that chenier ridges that developed after ca. 7000 cal yr BP in the east of the area sheltered it from marine inundation and although still connected to the sea through tidal creeks, low-salinity conditions persisted throughout the Neolithic period. There is no evidence that marine flooding caused the collapse of Liangzhu culture. Marine influence was stable and evolved slowly. Social and cultural causes may also have been important, but if environmental change triggered the collapse of Neolithic agricultural society here, other natural forces must be sought to explain this event.

The Quaternary stratigraphy of the Yangtze delta has been revealed by a deep (344.64 m) continuous borehole, the sediments of which are divided into four sections, the Early (Q1), Middle (Q2), and Late Pleistocene (Q3), and the Holocene (Q4). Six lithofacies include lacustrine, fluvial, coastal, drowned river channel, deltaic, and shallow marine in these time periods. The fluvial and lacustrine lithofacies prevailed during Q1and Q2; coastal and drowned river channel lithofacies periodically appeared in Q1, Q2, and Q3; shallow marine lithofacies dominated Q3; and deltaic lithofacies occurred in Q4. Based on stratigraphy, four transgressive events are inferred. Trace-element (Sr, Ba, B, Ga, V) content and ratios of Sr/Ba and B/Ga are considered with regard to their distribution in the various lithofacies. Geochemical facies criteria are established based on combined diagnostic indices: Sr > 160 ppm, B > 90 ppm, Sr/Ba > 0.35, B/Ga > 4.0 for the shallow marine lithofacies; Sr < 90 ppm, B < 50 ppm, Sr/Ba < 0.2, B/Ga < 2.5 for the terrigenous lithofacies. These indices correspond well to paleosalinity data obtained using the sedimentary phosphate method (Ca/Ca + Fe). Transgressive events identified by the geochemical indices are mostly the same as reflected by marine fossils. Nevertheless, geochemical indices can indicate the occurrence of a weak transgression, where marine fossils are rare.

The large prehistoric city of Liangzhu and its associated earthen dike emerged on the Yangtze delta-coast after two millennia of occupation in this area by scattered communities. Details of its development have been widely discussed in the literature. Our results reveal that the city was selectively built at the head of an embayment backed by hills, with close access to food, freshwater and timber, and with protection from coastal hazards. Radiocarbon and optically stimulated luminescence (OSL) dating shows that it was built around 4.8–4.5 ka, and the earthen dike was constructed a little later at ~ 4.1 ka. During this time, saltwater wetlands were changing to freshwater in response to rapid coastal progradation as the postglacial sea-level rise stabilized. This facilitated rice farming and furthered the development of the city with elaborate city planning. The younger large-scale earthen dike and artificial ponds possibly suggest increasing demand for flood mitigation and irrigation.

In the present study, nano-sized cuboid-shaped particles in Mg–Nd–Y are studied by means of Cs-corrected atomic-scale high-angle annular dark-field scanning transmission electron microscopy. The structure of the cuboid-shaped phase is identified to be yttrium (major component) and neodymium atoms in face-centered cubic arrangement without the participation of Mg. The lattice parameter a=5.15 Å. During isothermal aging at 225°C, Mg3(Nd,Y) precipitates adhere to surface (100) planes of the cuboid-shaped particles with the orientation relationship: $[100]_{{{\rm Mg}_{{\rm 3}} {\rm RE}}} \,/\,\,/\,[100]_{{{\rm Cuboid}}} $ and $[310]_{{{\rm Mg}_{{\rm 3}} {\rm RE}}} \,/\,\,/\,[012]_{{{\rm Cuboid}}} $ . The fully coherent interfaces between the precipitates and the cuboid-shaped phases are reconstructed and categorized into two types: $(400)_{{{\rm Mg}_{{\rm 3}} {\rm RE}}} $ interface and $(200)_{{{\rm Mg}_{{\rm 3}} {\rm RE}}} $ interface.

We report here investigations on the superstructure modulation induced by the ordering of carbon vacancies in the nonstoichiometric zirconium carbide of ZrC0.61, which was prepared by spark plasma sintering (SPS) of the mechanochemically synthesized ZrCx nanopowders. The sintered ZrC0.61 is found to exhibit an interesting microstructure of interlaced laminated sheets. In contrast to the previous long duration post annealing for realization of the ordered carbon vacancies in the rocksalt-structured transition metal carbide, the ordered carbon vacancies are directly obtained during the SPS process, and no post-annealing period is necessary. With the help of transmission electron microscopy, the superstructural nanodomains with the average size of ∼30 nm are identified.