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The Zhe-Min Uplift (ZMU) has undergone tectonic subsidence, which has been associated with a notable transgression in the northern marginal seas of China since the middle Pleistocene. However, its uplift history during the late Quaternary is still inadequate. The Old Red Sand (ORS) is a late Pleistocene deposit that is widely distributed along the southeastern coast of China. The ORS consists of partially-cemented fine- to medium-grained sand. In this paper, we focus on mud-rich ORS deposits of the Liushui area, Pingtan Island, Fujian Province, and report optically stimulated luminescence (OSL) ages, and new datasets of grain size, mineralogy (detrital zircon, clay and detrital minerals) and organic carbon and nitrogen isotope profiles to improve understanding of chronology, provenance, palaeoenvironmental evolution and tectonic infuence. Based on the OSL data, we hypothesize that the development of the ORS was associated with lower sea levels, with most deposition occurring within MIS4. Based on comparison of detrital zircon U Pb ages, the coarse fraction of the Liushui ORS was mainly derived from the Minjiang River, with modest input from weathering of coastal granites. The East Asian Winter Monsoon contributed some materials from the East China Sea shelf during the last glacial period, as indicated by the fine-grained nature of the Liushui ORS, low K-feldspar/plagioclase ratios, high dolomite content and the frequency of Neoproterozoic and Palaeoproterozoic detrital zircons. The deposition of the ORS was influenced by both the East Asian Winter Monsoon and sea level changes. The clay minerals in the mud layers of the Liushui ORS were dominated by kaolinite and illite, with little chlorite and no smectite, indicating that they originated from the Minjiang River. The TOC/TN ratios of the mud layers, as well as their isotope characteristics, indicate the organic matter was derived from marine sources, presumably during the transgression event in MIS5. The average uplift rate of the ORS was about 0.03 mm/yr. The uplift of the ORS provided new insights into the geological records of the ZMU, which differed from the subsidence observed in the northern region of the Minjiang River during the late Pleistocene. • The formation of the ORS was association with lower sea level, and the MIS4 was primarily the deposition stage. • During the last glacial, the more sediments from the East China Sea shelf were transported to the ORS by EAWM. • The mud layer was the transgression records during MIS5. • The distribution of the ORS was influenced by tectonic activity. [ABSTRACT FROM AUTHOR]

The geochemical compositions of sediments in the Dongshan Bay, a semi-enclosed bay on the southeast coast of China, were obtained to identify pollutant sources and evaluate the anthropogenic impacts over the last 100 years. The results indicated that the metal flux had been increasing since the 1980s. Enrichment factor values (Pb, Zn and Cu) suggested only slight enrichment. The proportion of anthropogenic Pb changed from 9% to 15% during 2000–2014. Coal combustion might be an important contamination source in the Dongshan Bay. The historical variation in the metal flux reflected the economic development and urbanization in the Zhangjiang drainage area in the past 30 years. According to the Landsat satellite remote sensing data, the urbanization area expanded approximately three times from 1995 to 2010. The δ 13 C values (−21‰ to −23‰) of the organic matter (OM) in the sediments indicated that the OM was primarily sourced from aquatic, terrigenous and marsh C 3 plants. Nitrogen was mainly derived from aquatic plants and terrigenous erosion before the 1980s. However, the total organic carbon (TOC) contents, total nitrogen (TN) contents and δ 15 N had been increasing since the 1980s, which suggested that the sources of nitrogen were soil erosion, fertilizer and sewage. In addition, the TOC and TN fluxes in the Dongshan Bay had significantly increased since the 1980s, which reflected the use of N fertilizer. However, the TOC and TN fluxes significantly decreased in the past decade because environmental awareness increased and environmental protection policies were implemented. [ABSTRACT FROM AUTHOR]

Detrital zircons from the Minjiang and Zhujiang Rivers in SE China have been analyzed for U/Pb ages and Lu–Hf isotopic compositions to constrain their provenance and the growth history of the continental crust of the Cathaysia Block. Zircon U/Pb ages show five major populations at 90–250 Ma, 400–500 Ma, 0.7–1.2 Ga, 1.6–2.0 Ga and 2.3–2.6 Ga. Proterozoic zircons have Hf isotopic signatures consistent with the remelted ancient crust and the involvement of juvenile crust. However, Phanerozoic zircons have Hf isotopic signatures indicative of reworked or recycled ancient crust. Crustal growth rates based on the two-stage Hf model ages of the detrital zircons indicate that 30% and 90% of present crust in the northeastern Cathaysia Block was formed by 2.5 Ga and 1.6 Ga, respectively, whereas <20% continental crust was formed by 2.5 Ga, and 80% by 1.6 Ga in the southwestern Cathaysia Block. Therefore, Neoarchean and Paleoproterozoic were two major periods of crustal growth of the Cathaysia Block. Our results also reveal that the tectono-thermal events at ∼370 Ma and ∼117 Ma may have occurred to the Wuyishan terrane in the northeastern Cathaysia Block. Jurassic zircon grains have Hf isotopic compositions more variable than Cretaceous grains, which may have been derived from different source rocks. The 140–120 Ma tectono-thermal events were likely related to the change of the subduction direction of the Paleo-Pacific plate from northward to northwestward at 140 Ma. The 112–90 Ma tectono-thermal events may be correlated with the rollback of the subducted paleo-Pacific plate at ∼110 Ma. [ABSTRACT FROM AUTHOR]

The evolution of seafloor erosion-siltation in urban bays has received wide attention owing to its high susceptibility to natural factors and human activity, Xiamen is a typical coastal city in China that has undergone rapid urban development. Here, we studied seafloor erosion-siltation in the sea to the east of Xiamen Island. In particular, we focused on the responses of erosion-siltation to changes in the natural environmental factors and intensive human activity. The spatial distribution and transport trends of surficial sediments, changes in sedimentary records, and erosion-siltation dynamics were analyzed based on surficial sediments, core sediment within a time span of ca.100 years, and new and historical bathymetric data. The results showed that surficial sediments were mainly transported to the northwest and southwest, three stage changes in sedimentary records have occurred, the shoreline gradually moved seaward and became straighter, and the erosion-siltation state shifted from slight erosion to siltation. Before the 1930s, climate change with alternating aridity and humidity controlled the influence area of the Jiulong River sediment input. During the subsequent period (1930s to the early 1970s) of enhanced human activity in the drainage basin, the increased river sediment input only promoted siltation in some of the study areas; however, after the 1970s, river sediment input was no longer a dominant factor in the evolution of erosion-siltation. During the rapid urban development in Xiamen, coastal development and construction on Xiamen Island resulted in a large influx of sediment into the sea directly. This compensated for the decreased river sediment input and shifted the study area toward siltation. Meanwhile, rapid siltation was triggered in some of sediment convergence areas and the Jinmen Channel, where the dredging and maintenance demands were low. While channel dredging and maintenance coupled with sediment back siltation caused significant short-term topography changes in the Xiamen East Channel. Land reclamation directly shrank tidal flats along Xiamen Island. Moreover, normal wind-generated waves and occasional intensification typhoon events affected the long-term evolution of these tidal flats via persistent erosion coupled with coastal transport, and drastic short-term erosion, respectively. • Riverine input fluctuated significantly under impact of natural and human activity. • Enhanced riverine sediment input only promoted siltation in some study areas. • Human activity dominated erosion-siltation evolution during rapid city development. • Coastal development gap led to varied erosion-siltation situation in two channels. • Reclamation, wave action and typhoon caused to the shrinking of tidal flats area. [ABSTRACT FROM AUTHOR]

A recent paper (Deng et al., 2017) reported detrital zircon geochronology from sandy sediments of the Lanyang River and the Zhuoshui River in the east and west Taiwan, respectively. They demonstrated that zircons from the Yangtze Block and the North China Block could be transported to the proto-Taiwan region by paleo-longshore currents. However, it is here suggested that, detrital zircons are unlikely to be transported over such long distances by paleo-longshore currents. Furthermore, the Min River in the Cathaysia Block might be a potential, and more accessible, primary provenance. The contribution of Min River to Taiwan sediments should be taken into account. [ABSTRACT FROM AUTHOR]

Sediment transport in estuarine systems has been of increasing interest for scientists during the past few decades. However, the mechanisms for sediment redistribution remain unclear. We characterized in detail sediment transport in the Xiaoqing River estuary using the mathematical Weibull function to partitiongrain-size components of surface sediments in the southwestern Laizhou Bay, Northeast China. Four partitioned components: finer than 4, 4.6-12.5, 23.4-63.3, and 67.1-132.6 μm were interpreted in terms of hydrodynamic conditions. During sediment transport, silt grains were suspended and moved seaward from three depositional centers, whereas fine-grained sands moved generally landward. Overall, sediments are transported clockwise in a generally NNE direction near shore and then turn eastward offshore. The mathematical partitioning method showed a great potential for future estuarine environmental studies. [ABSTRACT FROM AUTHOR]

In this study, we described the distribution pattern of suspended particulate matter (SPM) and its influencing factors in the waters around the Minjiang River Estuary. Further, we investigated the flocculation process of SPM and its underlying mechanism in the study area. The objectives were achieved using water temperature, salinity, turbidity, fluorescence and particle size distribution of SPM data measured in August 2009. As influenced by dilution from the Minjiang River water, the water column structure was significantly stratified in the estuary, with an obvious thermocline and halocline. The turbidity was relatively low in the surface water (SSC < 5 mg/l) but sufficient to form nepheloid layer in the near-benthic (SSC > 15 mg/l). Fluorescence was high (up to 10 μl/l) in the surface water, which was markedly lower and more uniform in the lower water layer. The total volume concentration and particle size of the SPM in the upper water layer were significantly higher than those of the lower water layer. The in-situ particle size frequency distribution of SPM markedly changed in the different water layers, whereas the dispersed particles were fine, with little difference in frequency distribution. The mean effective density of SPM was generally < 600 kg/m 3 in the surface and benthic water, and the values were slightly higher in the benthic water layer than in the surface water layer, with a significant increase in the middle water layer. The significant differences between the distribution trends of the total volume concentration and water turbidity were controlled by the size distribution of SPM. The concentration distribution of SPM was mainly influenced by source, re-suspension and thermocline, among other factors. Flocs widely occurred in the study area, and the flocculation mechanism of SPM varied in the different water layers. In the upper water layer, intense biological activity promoted the formation of stable macroflocs. In the benthic water layer, the biological activity was limited, the flocculation of sediment particles was mainly caused by physico-chemical attraction of inorganic particles, and the hydrodynamic conditions and high settling velocity were also unfavourable to the formation of macroflocs. [ABSTRACT FROM AUTHOR]

In this study, surface water samples were collected over several seasons from the Jiulong River mainstream (North and West Rivers) and estuary from 2013 to 2014. The concentration of dissolved inorganic carbon (DIC), stable carbon isotope composition (δ13C DIC), in-situ temperature, pH, and conductivity of the surface water were measured to study the source and fate of DIC in the Jiulong River. The results showed that the DIC concentrations decreased from upstream to downstream in the North River but increased in the West River, which was determined mainly by the lithology of the drainage basin. In spring, the river is fed by deep groundwater resources that are older and contain more DIC originating from carbonate weathering compared to surface water, resulting in the high concentration and δ13C DIC value of DIC. Whereas during the summer and autumn, the high runoff caused by frequent precipitation dilutes the DIC concentration of river water and the contribution of soil CO 2 is more important, resulting in lower DIC concentration and δ13C DIC value. δ13C DIC values indicate that the DIC in the Jiulong River was derived mainly from the chemical weathering of bedrock, and CO 2 outgassing was one of the main fates of the riverine DIC. Results of mixing ratio calculation in freshwater and seawater suggest that additional processes existed with the mixing process, which were identified as organic carbon degradation and respiration in summer and autumn and offshore water vertical mixing in winter and spring, but in general the spatial variation of DIC in the estuary was determined mainly by mixing of freshwater and seawater. This study complements our understanding of the sources and fates of DIC in small river systems on the continental margin of the East China Sea. • Riverine DIC content was determined by the lithology of the basin in Jiulong River. • CO 2 outgassing is one of the main fates of riverine DIC. • Significant seasonal variation of riverine DIC was found in Jiulong River. • Riverine DIC and marine DIC are not conservative mixed in the estuary. • Organic carbon degradation is the main additional process of DIC in the estuary. [ABSTRACT FROM AUTHOR]

The suspended particulate matter (SPM) is an important carrier of heavy metals transportation from land to sea, so it is significant to study the heavy metal pollution in SPM. The distribution and assessment of five heavy metals (Mn, Cr, Ni, Cu, and Pb) in SPM collected from Passur River and its estuary in Sundarban were studied in combination with water temperature, salinity, and turbidity. The results show that the heavy metal content and distribution in SPM are mainly controlled by runoff input, hydrodynamic process and the interaction process of salt and fresh water in estuaries. The quality evaluation results of heavy metals in SPM show that pollution degree is light. Studies on the heavy metals in SPM are of great significance to comprehensively evaluate regional pollution status and carry out early warning., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The concentrations of Cr, Ni, Cu, Zn, As, Cd, Pb, and Al in suspended particles were measured, and temperature, salinity, flow velocity and direction during a tidal cycle were observed before and after Typhoon Fung-wong at six stations in Quanzhou Bay, respectively. The comparison results show that, after the typhoon, the salinity in Quanzhou Bay decreased, whereas the concentrations of heavy metals increased by a factor of between 2 and 10, and the high heavy metal concentration corresponded to the low value of ratio between heavy metals and Al (HMs/Al), suggesting that these increased heavy metals were mainly from natural sources. Instantaneous unit width flux calculations for heavy metals at different stations indicate that sediments are an important source of heavy metals in suspended particles under the influence of typhoon, which has significantly contribution to understanding the impact of typhoons on the heavy metal pollution in the coastal area., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Two sedimentary cores in the Minjiang River estuary (SE China) are documented for grain size, clay minerals, heavy metals, magnetic parameters and Pb isotopes to investigate the source and historical variation of heavy metals. The MJK9 core was collected outside of the Minjiang River estuary, and the core is composed of mixed sediments, of which ~70% from the Yangtze River and 30% from the Minjiang River. It is thus difficult to be used for tracing the human activity along the Minjiang River. In contrast, the sediments of MJK16 core which was collected in a nearshore area are primarily from the Minjiang River. The enrichment factors of the sediments were <1.5, indicating minor pollution. The results indicate that the sediments of the MJK16 core have Cu and Pb concentrations increasing since 1980, associated with the increase of magnetic mineral concentration and (206)Pb/(207)Pb and (206)Pb/(208)Pb of the sediments. We compared the Pb isotopic compositions between our results and those for the deposit mining in the Minjiang River basin, and aerosols and coal dust in south China, and considered that Pb in the sediments of the MJK16 core was derived primarily from weathered rocks as well as industrial emission (e.g. coal combustion). The sediments have anthropogenic Pb concentrations ranging from 6% in 1950 to 23.7% in 2010, consistent with the impact of rapid urban and industrial development in China., (Copyright © 2014 Elsevier B.V. All rights reserved.)