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Abstract: This paper addresses the recent (1970s–1990s) processes of river mouth bar formation, riverbed aggradation and distributary migration in the Huanghe River mouth area, in the light of station-based monitoring, field measurements and remote sensing interpretation. The results show that the morphological changes of the river mouth bar have been closely associated with the largely reduced fluvial discharge and sediment load. Landform development such as bar progradation occurred in two phases, i.e. before and after 1989, which correspond to faster and lower bar growth rates, respectively. Fast riverbed aggradation in the mouth channel was strongly related to river mouth bar progradation. During 1976–1996, about 2.8% of the total sediment loads were deposited in the river channel on the upper to middle delta. Therefore, the river water level rose by a few meters from 1984 to 1996. The frequent distributary channel migration, which switched the radial channel pattern into the SE-directed pattern in the mid-1980s, was linked with mouth bar formation. Marine conditions also constrain seaward bar progradation. Furthermore, the history of river mouth bar formation reflects human impacts, such as dredging and dyking in order to stabilize the coastal area. [Copyright &y& Elsevier]

This paper systematically describes the molecular and isotopic characteristics of Meso- to Neoproterozoic (1.73–0.85 Ga) sediments from the Jixian section, Yanshan Basin, North China. A correlation is made between molecular fingerprints and paleoenvironmental and paleontologic data acquired from these strata. The agreement between these parameters suggest that the biomarkers preserved in these Proterozoic sediments are good indicators of the evolution of the paleoenvironment and early life in the Yanshan Basin. The fact that extended regular isoprenoids (>C20) were detected in most of the studied samples suggest a sustained lipid input to sedimentary organic matter from halophiles and other possible archaebacteria through Meso- to Neoproterozoic. Two dehydroabietin isomers (i.e. 18- and 19-norabieta-8,11,13-trienes) were unexpectedly present in these samples, which provides evidence suggesting that the compounds with abieta structure could be derived from primitive organisms such as algae. The stable carbon isotope characteristics of kerogen and coexisting carbonate show a rapid decline in atmospheric CO2 concentration from 1.73 to1.58 Ga, and a stable concentration afterwards. The difference (ΔC) in isotopic composition between carbonate and associated kerogen lies in zonal variations along the stratigraphic sequence, which can be attributed to the alternations of marine transgressions and regressions that occurred in the Yanshan Basin during the Proterozoic. The carbon isotope relationships between kerogen and alkanes from these strata are consistent with the hypothesis that before 1.4 Ga both n-alkanes and isoprenoids had been derived mainly from heterotrophic halophiles and other archaebacteria, but after that only isoprenoids originated from archaebacteria whereas n-alkanes were possibly derived from photosynthetic organisms. Changes in the source of n-alkanes around 1.4 Ga may suggest a decline of heterotrophic reworking to primary lipids, which can be related to the formation of a quiet, shallow-water environment of an epicontinental sea at this stage in the Yanshan Basin. [Copyright &y& Elsevier]

The temporal and spatial distribution of total nitrogen and total phosphate in the sediments of a shallow eutrophic Chinese lake (Lake Chao), and their relationships with the physical and chemical features of sediments, and their effects on the lake water quality and trophic state, are presented in this paper. The following results were obtained: (1) higher concentration of Tot-N and Tot-P in the sediments occurred in the summer and the autumn seasons; (2) higher annual average Tot-N and Tot-P concentrations were observed in the sediments near the various river mouths and in the western part of the lake; (3) Tot-N and Tot-P concentration in the lake sediments generally increased with increase in lake sediment Eh, pH, and Al2O3, and declined with decrease in lake sediment size diameters and SiO2; and, (4) correlations were observed in both the temporal and spatial distributions between the trophic state, Tot-N and Tot-P concentration in the lake water, and the Tot-N and Tot-P concentration found in the lake sediments. [ABSTRACT FROM AUTHOR]

Ten samples of slope-wash and colluvial deposits from a trench wall at Xiyangfang, Yanqing County, located in the northern margin fault zone of the Yanqing Basin, about 90 km northwest of Beijing, have been dated by both green light stimulated emission (GLSL) and infra-red stimulated emission (IRSL). Four of the samples were measured in both Adelaide (Risø equipment) and Beijing (Daybreak equipment), with essentially consistent results. The paper gives a comparison of equivalent dose values obtained by both GLSL and IRSL. The Xiyangfang trench wall presents four fault-scarp-collapsed wedges, showing a clear normal faulting pattern, which can be interpreted as a record of palaeo-earthquake events, covering a time period from about 100 ka to the modern. A return time of about 7000 yr is suggested for events at this site. An attempt is made to correlate the dating records with the local earthquake history of destructive earthquakes in the last 2000 yr. [Copyright &y& Elsevier]

Abstract: This paper presents a revision of a river-flow response model by Dust and Wohl (2012). In particular, serious confusion of the relationship between sediment transport capacity and width-to-depth ratio is clarified. As a consequence, we propose a reasonable qualitative model for understanding the complexity of river responses as illustrated in an appropriately modified form of the Lane diagram, which identifies the equilibrium condition based on the balance between channel aggradation and degradation. [Copyright &y& Elsevier]

This paper reports bulk organic carbon isotope data from a laboratory study designed to evaluate whether acid chromium reduction (ACR), commonly used to prepare rock/sediment samples for sulfur isotope analysis, significantly fractionates bulk organic carbon isotopes compared with the standard decarbonation (SD) method in Quaternary coastal plain incised valley sediments. In this study, 36 sediment samples obtained from a Quaternary sediment core from the Qiantang River incised valley on the East China coastal plain were tested. The results show differences in the δ13C org values between the ACR and SD methods for Quaternary incised valley sediments ranging from – 0.97‰ to +0.34‰, with most values (86%) showing a negative bias. Approximately half of the samples yield δ13C org values that differ by ≥ ± 0.3‰. The carbonate and total organic carbon (TOC) contents of the sediment samples have no significant effects on the bulk organic carbon isotopes derived by ACR. There is also no obvious correlation between the organic carbon loss by ACR and the difference of the δ13C org values. We believe that ACR loses more 13C-enriched labile organic carbon and/or volatile organic compounds (VOCs) than SD, which leads to a negative bias in the δ13C org values. The mineral composition was speculated to be related to a significant positive bias in the δ13C org values by ACR observed in two particular samples and requires further study. Consequently, ACR should be used with caution for sediments containing primarily young labile organic carbon with medium to high TOC contents (TOC ≥ 0.5 wt %), as it may cause a large offset of the δ13C org values compared with SD. However, ACR may be used for sediments containing organic matter primarily from terrestrial plants with relatively low TOC contents (TOC < 0.5 wt %). • Chromium reduction for analysis of bulk δ13C org values in Quaternary sediments were tested. • Chromium reduction significantly fractionated δ13C org values in Quaternary sediments. • Chromium reduction should be used with caution for analysis of δ13C org values in sediments. [ABSTRACT FROM AUTHOR]

Accurate inversion of sound velocity in a Holocene stratum and a Quaternary stratum was achieved based on rich high-resolution sub-bottom profiles and boreholes in the Jinzhou Bay, Bohai Sea of China. The average value of the sound velocity is 1540.2 m/s in the Holocene stratum and 1764.7 m/s in the Quaternary stratum. The fitting analysis shows that there is an obvious positive linear correlation between the sound velocity and the burial depth of the stratum, with a gradient of 4.5 s−1. The method involving the solution of over-determined equations was innovatively put forward to explore the sound velocity characteristics of different types of sediments. The eigenvalues of the sound velocities of seven types of sediments and weathered rock in the study area are solved: the sound velocities of mud, muddy sand, muddy silty clay, muddy clay, silty clay, clay, silty sand, and strongly weathered rock are 1513.7 m/s, 1484.3 m/s, 1532.0 m/s, 1511.3 m/s, 1693.9 m/s, 1602.7 m/s, 1599.4 m/s, and 2137.7 m/s, respectively. And statistical analysis shows that the sound velocity of the sediment in the study area has obvious quadratic correlations with the void ratio and compressibility. • Based on sub-bottom profiles and boreholes datasets, this paper develops a method of acoustic inversion of seabed sediment. • Innovatively establishing over-determined equations to solve sound velocities of different types of sediments. • Findings can provide important reference values to the geophysical survey and the development of seabed geoacoustics. [ABSTRACT FROM AUTHOR]

Endemic fluorosis is a worldwide health concern, which may be related to enhanced fluorine (F) in soil via food-to-mouth or respiratory system activity exposure to humans. Until now, continental scale data on F in the pedosphere is still deficient in China. In this paper, the distribution of enhanced F and the factors influencing this distribution are investigated using data of the China Geochemical Baseline project. The median values of F were 488 and 456 ppm in top and deep soil, respectively. In terms of spatial distribution, F in topsoil of China presents coastal and mountain low-value zones, central-south plain and southwest Karst high-value zones, and a northwest arid basin high-value zone. Thirty-three F geochemical provinces were delineated with F values of >700 ppm, which were predominately associated with geological background, intensive evaporation, and human activities. The formation of a high F anomaly area from the central–southern part to the southwestern part of China was related to the calcium-enriched soil and the superimposed coupling of multiple factors including the high F geological background, such as F-enriched organic matter strata, F-enriched phosphorus-bearing strata, F-enriched gypsum salt strata and mineralization processes. The high F anomaly area in northwestern China was not only related to the high geological background, but also associated with the secondary enrichment caused by evaporation. • Geochemical distribution characteristics of F in drainage catchment sediment/alluvial soil of China were studied. • The main factors of F enrichment are geological background, hydrothermal processes, evaporation and human activities. • The supernormal enrichment of F in southwest China is caused by geological background and hydrothermal processes. [ABSTRACT FROM AUTHOR]

• A hybrid statistical model for integrated ecological risk assessment of PAHs. • Analysis of interdependence among PAHs exposure concentrations according to copulas and HACs. • Inapplicable assumptions that concentration additivity and independent action were avoided. • SQGs provide toxicological evidence for ecological risk assessment of PAHs. For integral ecological risk assessment of polycyclic aromatic hydrocarbons (PAHs), the interdependence is always ignored by assuming concentration additivity (CA) and independent action (IA). This paper proposed a hybrid assessment model, named hierarchical Archimedean copula integral assessment (HACIA), to treat inherent relations and assess the multi-dimensional holistic ecological risks of exposure concentrations of 16 PAHs. The HACIA model couples with hierarchical Archimedean copulas (HACs) and ecological evaluation criteria, sediment quality guidelines (SQGs), which depends on copulas to construe the connotations of correlations among exposure concentrations of PAHs. The two case studies, the exposure concentrations of 16 PAHs from Taihu Lake in China and the Bay of Bengal coast in Bangladesh, respectively, are used to verify the adaptability and feasibility of HACIA model and evaluate their comprehensive environmental risk. In addition, a theoretical and empirical comparison with three frequently-used methods was provided objectively, which focused on presuppositions, principles, evaluations and consequences. The results indicated that the HACIA model has good feasibility and applicability to evaluate the synthetic ecological risk according to PAHs exposure concentrations, remedies for the situation that the interdependence among other methods is neglected, and can produce more deliberate classification of hazards theoretically and better demonstrations of assessment results than the other three. Although the more accurate risk assessments rely on detecting quantity of samples, the integral ecological risk assessment based on the proposed HACIA model is reliable and robust because of its reasonable structure. [ABSTRACT FROM AUTHOR]

Thallium (Tl) is an uncommon toxic element, with an even greater toxicity than that of As, Hg and Cd. Steel-making industry has been identified as an emerging new significant source of Tl contamination in China. This paper presents a pilot investigation of the contamination and geochemical transfer of Tl and associated metal(loid)s in river sediments affected by long-term waste discharge from the steel-making industry. The results uncovered an overall Tl contamination (1.96 ± 0.42 mg/kg) across a sediment profile of approximately 1.5 m in length, even 10 km downstream the steel plant. Highly elevated contents of Pb, Cu, Cd, Zn and Sb were found in the fluvial sediments, displaying strong positive correlations with Tl contents. Elevated levels of geochemically mobile Tl as well as Cd, Zn, Cu and Pb occurred in the fluvial sediments, signifying anthropogenic imprints from steel production activities at high temperature. Levels of contamination and ecological risk were calculated to be moderate to considerable for Tl, Cu, Zn and high to very high for Cd, Pb, Sb. The results highlight that there is a great challenge in view of potentially considerable Tl pollution due to continuous massive steel production in many other parts of China. It is high time to initiate process-based management of Tl contamination control for the ambient aquifer system in the steel-making area. Image 1 • Steel industry is an emerging new significant source of Tl pollution in China. • Steel-making activities have generated Tl contamination imprints in river sediments. • High levels of Tl as well as Pb, Zn, Cd, and Sb were identified in the sediments. • Higher than 30% of Tl is geochemically mobile, bearing high ecological risks. • It indicates great challenge for Tl pollution in China due to massive steel industry. [ABSTRACT FROM AUTHOR]

Streamflow and sediment runoff are important indicators for the changes in hydrological processes. In the context of environmental changes, decreases in both streamflow and sediment (especially in the flood season) are often observed in most of the tributaries of the middle Yellow River in China's Loess Plateau. Understanding the effect of human activities could be useful for the management of soil and water conservation (SWC) and new constructions. In this paper, changes in streamflow and sediment during the flood season (June–September) of the 1966–2017 period in a typical loess hill and gully landform basin were analyzed. Basin-wide rainfall of the flood season decreased nonsignificantly with an average rate of −0.6 mm/flood season for the whole study period by using the trend-free pre-whitening based Mann–Kendall trend test, while the decreasing rate was weakened on the time scale. A remarkable warming trend (1985–1999) and two decreasing trends (1966–1984 and 2000–2017) were observed, and the overall increasing trend could be found in air temperature series with a rate of 0.01 °C/flood season during the study period. Statistical models were developed to describe the rainfall-runoff and rainfall-sediment processes in the pre-impact period (when the hydrological series was stationary). Furthermore, the relative effects of climate variability and human activities on hydrological changes were quantified. Results proved the dominant role of human activities (versus climate variability) on the reductions of both streamflow and sediment load. The relative contribution of human activities to streamflow decrease was 84.6% during the post-impact period 1995–2017, while the contributions were 48.8% and 80.1% for two post-impact periods (1982–1996 and 1997–2017), respectively, to the reduction of sediment load. Besides, the effect of the exclusion of anomalous streamflow or sediment events on change-point detection was also analyzed. It indicated that the anomalous events affect the detection of change points and should be given full consideration in order to decide whether to remove them in the change-point detection. Otherwise, the full series with anomalous samples will completely affect the attribution results of hydrological changes. We also suggest that large-scale SWC measures with different construction quality and operational life could intercept and relieve most floods and high sediment concentration processes, but may amplify the peaks of streamflow and sediment when the interception capacities are exceeded under the condition of extreme rainstorm events. [ABSTRACT FROM AUTHOR]

In recent decades, the streamflow and sediment of the Yellow River has decreased sharply, especially the sediment discharge. The factors that lead to this phenomenon have become a widely concerned problem of the whole society. The analysis of abrupt change points of hydrological series is the key to divide datum period, so it is an important work in the research of streamflow and sediment reduction cause. So far, many methods have been proposed to detect abrupt change. However, most methods have great uncertainty due to the deficiencies of irrational structure of test statistics, ideal hypothesis or subjectivity. In this paper, a new method called moving average difference method for abrupt change points detection is proposed. It is proved to be effective through comparison with four commonly used methods via both synthetic series and real data case study. The results show that the proposed method has four distinct advantages: (1) The test statistic structure of the method has physical significance and is intuitive to understand; (2) It is more accurate in abrupt change detection; (3) It can detect all of the abrupt change points at one time; (4) It can detect the abrupt changes and calculate the corresponding mutation intensity simultaneously. [ABSTRACT FROM AUTHOR]

Heavy metal pollution in sediment is one of the most serious problems in water bodies, including rivers, which can cause secondary pollution when environmental conditions change. In this study, surface sediment samples collected from the four main tributaries of Dongting Lake (i.e., Xiangjiang River (XR), Zishui River (ZR), Yuanjiang River (YR), and Lishui River (LR)) were analyzed for concentrations of Zn, Cr, Cu, As, Cd, and Pb. The spatial distribution, source, and potential ecological risk of these metals were determined. The results suggest a great spatial heterogeneity of heavy metals in the sediment of the studied rivers. Heavy metals had highest concentrations in the sediment of XR, especially midstream and downstream. A principal component analysis (PCA) and correlation analysis indicated that Cd and As were mainly from industrial wastewater and mineral mining, Cr came from natural process and agricultural activities, and Zn and Cu potentially from both. Pb was originated from atmospheric deposition and river inflow transportation. According to the geo-accumulation index ( I g e o ), enrichment factor (EF), and risk index (RI) assessment, heavy metals pollution was highest in the sediment of XR, and Cd was the main pollutant in the sediment of XR, presenting considerable potential ecological risk. This may contribute to heavy metal pollution in Dongting Lake. This paper provides a reference for the aquatic environmental management of heavy metals in Dongting Lake area and its tributaries. [ABSTRACT FROM AUTHOR]

The occurrence of eight perfluorinated compounds (PFCs) in the surface sediments from 10 sampling sites spread across the Danjiangkou Reservoir was investigated by isotope dilution ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) after solid-phase extraction (SPE). All the sediments from the 10 sites contained detectable levels of PFCs. The total concentration of the target PFCs in each sediment sample (C∑PFCs) ranged from 0.270 to 0.395 ng g−1 of dry weight, and the mean value of C∑PFCs was 0.324 ± 0.045 ng g−1 of dry weight for the whole reservoir. For each perfluorinated compound in one sediment, perfluorooctane sulfonate (PFOS) or perfluoro-n-butanoic acid (PFBA) consistently had a higher concentration than the other six PFCs, while perfluoro-n-octanoic acid (PFOA) was always undetectable. In terms of spatial distribution, the total and individual concentrations of PFCs in sediment from downstream sites of the Danjiangkou Reservoir were higher than those from upstream sites. Factor analysis revealed that PFCs in the sediment samples originated from electroplating and anti-fog agents in industry, food/pharmaceutical packaging and the water/oil repellent paper coating, and the deposition process. The quotient method was utilized to assess the ecological risk of PFCs in the sediments of the Danjiangkou Reservoir, which showed that the concentrations of PFCs were not considered a risk. In this study, detailed information on the concentration level and distribution of PFCs in the sediments of the Danjiangkou Reservoir, which is the source of water for the Middle Route Project of the South-to-North Water Transfer Scheme in China, was reported and analyzed for the first time. These results can provide valuable information for water resource management and pollution control in the Danjiangkou Reservoir. [ABSTRACT FROM AUTHOR]

Multiple lines of evidence revealed that enormous CO 2 was input into the ocean-atmosphere system during Oceanic Anoxic Event 1a (OAE 1a), which led to a series of environmental perturbations (e.g. temperature rising, enhanced weathering, promoted primary productivity and marine anoxia). Among them, increased carbon isotope fractionation (Δ13C carb-org) between the carbonate (δ13C carb) and organic carbon (δ13C org) in the sediments is one of the most important indicators to the enhanced atmospheric pCO 2. However, only a few research reported high-resolution paired carbon isotopes during OAE 1a, which were almost limited around the western Tethys. Here, we report new paired carbon isotopes of the Early Cretaceous sediments from the ODP site 866A in the western Pacific and the Lingshan Island section in the Sulu orogenic belt. The δ13C carb curves from both sections correlate well with OAE 1a, in which a positive δ13C carb excursion is identified between the C3–C6 segments. The Δ13C carb-org displays a ∼7–11‰ positive shift coinciding with the δ13C carb excursion, indicating a remarkable increase and a gradual decrease in CO 2 in water and atmosphere, which further support significant atmospheric pCO 2 changes during OAE 1a on a global scale. The sediments also show a few variations in carbon isotope records during OAE 1a between different locations, which may reflect different influences from local environments, and the deviations of stratigraphic correlation and diagenesis cannot be ruled out either. • The carbon isotopes from both sections correlate well with OAE 1a. • Atmospheric pCO 2 rose in early OAE 1a and fell in late OAE 1a on a global scale. • The atmospheric pCO 2 changes show a few variations between different locations. [ABSTRACT FROM AUTHOR]

The authors respond to the comments made to their paper regarding the metasedimentary source for the Jiuyishan fayalite-bearing A-type granite in China. They argue on the statement by the discussers about their reasons for proposing a sedimentary source. They examine a suggestion on an I-type connection for Mesozoic granitoids in the South China Block including the Jiuyoshan granite. They elaborate on the proposal that felsic magmas derived from metasedimentary source are strongly peraluminous.

The article examines the factors that initiated the formation of the Taklimakan Desert in Tarim Basin, China. They have analyzed the surface microtexture and particle size of the interbedded light yellow silt from the Xiyu and Artux Formations. The paper provides stratigraphic evidence for the onset of dune building in the Tarim Basin. The investigations indicate that the dominant direction of sand dune movement is northeasterly. The study also suggested that central Tibet had an elevation of about 4 kilometer by at least 35 million years ago.