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Several long half-life natural and anthropogenic radionuclides, including 137Cs, 226Ra, 232Th, and 40K, in a 45 cm-long sediment core collected from the east continental shelf of Hainan Island, South China Sea, have been analyzed. The results showed that mean activity of 137Cs, 226Ra, 232Th, and 40K were 2.03 ± 1.2, 20.4 ± 1.8, 45.7 ± 3.0, and 520.0 ± 20.0 Bq/kg, respectively. Radium equivalent activity and External hazard index imply a low radiation, and the study area could serve as a background reference value for environmental radionuclides in east continental shelf of Hainan Island, South China Sea.

Dating recent sediment archives (

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are microbial molecular fossils ubiquitous in natural environments. The correlation between the Methylation Index of brGDGTs (the M B T 5 M E ' paleothermometer) and temperature offers an important tool for reconstructing past terrestrial temperatures. However, factors other than temperature could also affect the distribution of brGDGTs in lacustrine systems, hampering the quantitative application of this paleothermometer. Here we investigated brGDGT distributions in contemporary sediments collected from 52 lakes in mid-latitude Asia. Combined with published brGDGT data from other lakes across the globe, we have found a strong salinity control on the relative abundance of 5-methyl brGDGTs versus their late-eluting isomers (including 6-methyl, 7-methyl, and unknown isomers). This allows the development of novel indices based on the isomerization of brGDGTs for tracing past lake water salinity. We also demonstrate that salinity-controlled isomerization of pentamethylated and hexamethylated brGDGTs can significantly impact the M B T 5 M E ' paleothermometer, potentially leading to an overestimation of past temperature, but the temperature signal can be extracted out of the M B T 5 M E ' index after correcting the salinity effect. As demonstrated in application to a Lake Qinghai (China) sediment core spanning the last 18 kyr, our finding could facilitate the simultaneous retrieval of reliable temperature and salinity records using brGDGTs in lacustrine settings, in particular for lakes that have experienced large salinity changes during the geological past.

This paper describes the pollution level in sediment core collected from Sunairi Point of Karachi coastal area Pakistan. The sediment was characterized in terms of particle size, pH, total organic carbon, calcium carbonate, metals and mineralogical composition of sediments. The metals were determined using proton induced X-ray emission. It appeared from the results of grain size that sediment of core was mainly sandy in nature and neutral pH was observed throughout the core. The calcium carbonate in the core sediment seemed to be dependent on the pH outline of the sediment. The results of heavy metals in the sediment core indicated a significant upward enrichment in heavy metals with the highest concentrations found in the upper most layer sediments, may be due to anthropogenic activities, which could be the cause of upward enrichment in heavy metals. The pollution load index values, although showed no pollution, but showing an increasing trend from bottom to top in core, may be due to the influence of anthropogenic sources. The average geo-accumulation index values for sediment core showed that sediments were moderately polluted with Co and Pb. The results of sediment quality guidelines of United States Environmental Protection Agency, indicated, sediment of core was moderately polluted with Ni and Zn. It was concluded from the guidelines that heavy metals in sediment may cause danger to aquatic life. It was also inferred from the study that Sunairi Point area of Karachi coast is facing moderately metals pollution which increased with time.

We present results of multiproxy analysis of a sediment core collected from Billy Slope Meadow, a spring-fed wet meadow in Range Creek Canyon, Utah. Range Creek Canyon was the home to Fremont maize farmers between roughly 1200 and 800 cal BP (AD 750–1150). Stable carbon isotope analysis of core sediments from Billy Slope Meadow indicate the Billy Slope Meadow site was used as a field for maize agriculture during that time. Some scholars have suggested the florescence of the Fremont culture may have been driven by increased summer precipitation, which improved the economic profitability of dry farming maize. But analysis of pollen, macroscopic charcoal and sediment geochemistry from Billy Slope Meadow, and a comparison with a local tree-ring chronology indicate the Fremont period in Range Creek Canyon was probably marked by reduced summer precipitation, and not an invigorated monsoon. The Fremont maize farmers of Range Creek Canyon therefore likely used winter snowpack-derived water from Range Creek for maize agriculture. This observation has significant implications, as using creek water rather than direct precipitation and runoff necessitates the construction of dams irrigation infrastructure, limited evidence for which has been reported by archaeologists working in the Fremont region.

High-altitude lake sediment can be used as a natural archive to reconstruct the history of pollutants. In this work, the temporal distribution of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were determined using a high-resolution gas chromatography coupled with high-resolution mass spectrometer (HRGC/HRMS) in an alpine lake sediment core collected from the southern Tibetan Plateau (TP) to examine whether the expected decreasing trends due to the implementation of the international Conventions could be observed. The concentrations of PCBs and PBDEs in the sediment core were in the range of 11.8-142 pg/g dw and ND-457 pg/g dw, and their fluxes were in the range of 2.51-31.7 ng/(m2·yr) and ND-43.2 ng/(m2·yr), respectively. The prevalence of low-chlorinated (tri-CB) PCBs and low-brominated (tri- to tetra-) PBDEs in most sections of the sediment profiles was observed, suggesting that the light molecular weight PCBs and PBDEs have most likely reached lake sediments by long-range atmospheric transport from distant sources. Despite the restrictions on their applications, the sediment records for the concentrations and fluxes showed no corresponding decreasing trend with restrictions for PCBs, which suggested that these POPs (e.g., PCBs) were still emitted to the environment owing to the influence of primary or secondary emissions. To our knowledge, this is the first report on input history of atmospheric PCBs and PBDEs recorded in TP Lake sediment.

Sediment oxygen demand (SOD) measurement currently requires a long preparation time and bulky experimental equipment, which represent major obstacles to conducting SOD measurements. We developed a new SOD measurement method that can be easily conducted in a shorter time than the existing laboratory method. The undisturbed sediment core was transferred into the custom-made small glass vial (inner diameter 12.8 mm, length 125 mm). The SOD sample was incubated in the dark with or without stirring the overlying water inside the vial. The change in DO concentration was measured using a non-contact fluorescent oxygen sensor, and then the SOD was calculated. For comparison and verification of the new method, SOD was also measured using a large undisturbed sediment core (inner diameter 11 cm, length 50 cm). The SOD measurements using the new method were positively correlated with the SOD measurements using the large undisturbed sediment core, suggesting that the new method is a feasible alternative to the conventional method. In the new method, many SOD measurements can be taken from a single sediment core sample. This makes it possible to reduce the uncertainty associated with the highly heterogeneous structure of the sediments, and thus the new method has great advantages in obtaining reliable SOD data. A novel high-throughput method for SOD was developed that shortens sample preparation time and improves convenience of measurement. The new method is expected to contribute substantially to the accumulation of SOD monitoring data and to make great progress in elucidating the dynamics of dissolved oxygen in lakes.

A mass balance modelling approach was used to help understand the movement and impacts of tritium discharged from Canada Deuterium Uranium (CANDU) reactor facilities into Lake Ontario. A concentration-time model, previously developed, is updated in this study. Historical and projected tritium concentrations for Lake Ontario waters are presented. A model calculated accident scenario (10 times highest accidental release) indicates the importance of dilution to the dispersion of tritium; a “modelled” release in 2016 has tritium levels declining by the year 2030 to “previous 2016 levels”. As part of the mass balance approach, lake-bottom sediments were considered as potential radionuclide “sinks”. Tritium porewater results were noted as perturbations at depth in both short (30–50 cm cores) and long sediment core profiles (to 300 cm). These change in tritium concentrations with depth may have been due to CANDU emissions (as the most likely source) over time, based on records of accidental releases of tritiated coolant water. However, the exact process (advection and/or diffusion) responsible for the penetration of tritium into the lake bottom requires additional physical and hydrogeological characterization of the lake bottom sediments.

Polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs) were detected by gas chromatography–mass spectrometry in the sediment core form Poyang Lake. The concentrations of...

Fishery activities are an important source of microplastic pollution in coastal areas but have received little attention. The Beibu Gulf, a traditional fishing ground of China and the China-Indo Peninsula, was selected in this study, and the focus was on the impacts of fishery activities on the horizontal distribution of microplastics in sediment. The results showed that the dominant contaminants (polypropylene fibers and polyethylene fibers) might originate from the abrasion of fishing gear and contributed to 61.6% of the total abundance of microplastics in surface sediment. The abundance of polypropylene fibers and polyethylene fibers exhibited a strong correlation (R2 = 0.8586, p = 0.015) with values of fishery yields of different districts, which highlighted the effects of different fishery activities on microplastic contamination in marine sediment. Microplastics could be "hidden" in deep sediment to a depth of 60 cm. The estimated storage of microplastics in deep sediment (185 tons) was 5 times that in surface sediment. The assessment of microplastic storage worldwide might be underestimated because most previous studies only examined surface sediment. The abundance distribution and size distribution of microplastics in the sediment core suggested long-term burial of microplastics in deep sediment. Bioturbation might be responsible for the vertical transport of microplastics, leading to "fresh microplastics" preservation in "old sediment".

Organic proxies have been widely used to reconstruct temperature and terrestrial input variation at the interface between land and sea. However, the impact of human activities on these proxies has been little constrained, which might cause the misinterpretation of the sediment profile. In order to study the climatic and human impact on the environment, proxies in coastal regions, glycerol dialkyl glycerol tetraethers (GDGTs) in a sediment core spanning 115 years was analyzed from Beibu Gulf, China. The results indicate that isoprenoid GDGTs in the Beibu Gulf were mainly derived from Thaumarchaeota and the branched GDGTs originated mainly from terrestrial soil bacteria. The TEX86 index was applied to reconstruct the temporal SST variation. The results show that variation of TEX86-derived SST is controlled mainly by East Asian Monsoon system and partly by ENSO events. The methylation index of branched tetraethers or the cyclization index of branched tetraethers (MBT/CBT) derived mean annual air temperature (MAAT) agreed with MAAT record at the Qinzhou Station before 1982 AD. However, the population growth and economic development after 1982 AD caused the reduction of terrestrial organic matter input and increase of nutrient, leading to the thriving of Thaumarchaeota and increasing of in situ branched GDGTs proportion, which created the scatter of the MBT/CBT-reconstructed MAAT after 1982 AD. Therefore, human influence on GDGT proxies can be constrained in this way to avoid misinterpretation of paleoclimate and paleoenvironment records.

International audience; Since 1945, a large amount of heterogeneous data has been acquired to survey river sediment quality, especially concerning regulatory metals such as Cd, Cr, Cu, Hg, Ni, Pb, and Zn. Large-scale syntheses are critical to assess the effectiveness of public regulations and the resiliency of the river systems. Accordingly, this data synthesis pro- poses a first attempt to decipher spatio-temporal trends of metal contamination along seven major continental rivers in Western Europe (France, Belgium, Germany, and the Netherlands). A large dataset (>12,000 samples) from various sediment matrices (bed and flood deposits – BFD, suspended particulate matter – SPM, dated sedi- ment cores – DSC) was set up based on monitoring and scientific research from the 1950s to the 2010s. This work investigates the impact of analytical protocols (matrix sampling, fractionation, extraction), location and time fac- tors (related to geology and anthropogenic activities) on metal concentration trends. Statistical analyses high- light crossed-interactions in space and time, as well as between sediment matrices (metal concentrations in SPM ≃ DSC > BFD) and extraction procedures (also related to river lithology). Major spatio-temporal trends are found along several rivers such as (i) an increase of metal concentrations downstream of the main urban in- dustrial areas (e.g. Paris-Rouen corridor on the Seine River, Bonn-Duisburg corridor on the Rhine River), (ii) a long-term influence of former mining areas located in crystalline zones, releasing heavily contaminated sedi- ments for decades (Upper Loire River, Middle Meuse section), (iii) a decrease of metal concentrations since the 1970s (except for Cr and Ni, rather low and stable over time). The improvement of sediment quality in the most recent years in Europe reflects a decisive role of environment policies, such as more efficient wastewater treat- ments, local applications of the Water Framework Directive and urban industrial changes in the river valleys.

A sedimentary record of the 16 polycyclic aromatic hydrocarbon (PAH) pollutants from Dongping Lake, north China, is presented in this study. The influence of regional energy structure changes for 2–6-ring PAHs was investigated, in order to assess their sources and the impact of socioeconomic developments on the observed changes in concentration over time. The concentration of the ΣPAH16 ranged from 77.6 to 628.0 ng/g. Prior to the 1970s, the relatively low concentration of ΣPAH16 and the average presence of 44.4% 2,3-ring PAHs indicated that pyrogenic combustion from grass, wood, and coal was the main source of PAHs. The rapid increase in the concentration of 2,3-ring PAHs between the 1970s and 2006 was attributed to the growth of the urban population and the coal consumption, following the implementation of the Reform and Open Policy in 1978. The source apportionment, which was assessed using a positive matrix factorization model, revealed that coal combustion was the most important regional source of PAHs pollution (&gt, 51.0%). The PAHs were mainly transported to the site from the surrounding regions by atmospheric deposition rather than direct discharge.

Assessment of microplastics (MPs) in sediment cores is necessary to unveil global plastic pollution since most of the plastic litter might have been stored in sediment columns. In the current study, MPs inventory was determined in a 105 cm sediment core, collected in the Golden Horn Estuary, Sea of Marmara. Radiodating of sediment profile by using naturally occurring 210Pb and fission product 137Cs allowed us to couple the retrospective of global MP production to sediment MPs inventory. More than 90% of total MPs inventory was found in the deep layer of the sediment column (below 15 cm). Small MPs (20–200 μm) were more abundant than large ones (200–4000 μm). Elevated concentrations of MPs were attributed to industrial and municipal effluent of Istanbul metropolitan. On a local scale, this study suggests that the Golden Horn Estuary was polluted with MPs before the 1950s, and the abundance of MPs reached a maximum in the 1980s. We also propose on a global scale that “the missing” plastics might have been buried in deep sediment and radiodating of sediment is useful to reveal their historical input records.

International audience; F-specific RNA bacteriophages (FRNAPHs) are commonly used as indicators of faecal and viral contamination in waters. Once they enter surface waters, the exact role of suspended solids, sediments and hydro-meteorological factors in their fluvial fate and transport is poorly understood, and long-term studies (e.g., over years) are lacking. In this study, FRNAPH concentrations and genogroup distribution were measured in the Orne River (France) during two years at weekly intervals, and during four storm runoff events. Hydro-meteorological driving factors were investigated at both time scales. FRNAPH concentrations and genogroups at different depths of a riverbank sediment core were also examined to better discriminate the origin of the faecal pollution. During low flows, the FRNAPH and the suspended solid transport were decoupled and the FRNAPH concentrations were mainly correlated with the air and water temperature. During storm runoff events, the FRNAPH concentrations only showed a significant correlation with conductivity, turbidity and water discharge. Despite the uncertainty of the predictions, multi parameter regression models using hydro-meteorological variables were suitable to predict log transformed FRNAPHs’ concentrations at low flows with a standard error of 0.46. Model performance using the storm runoff events dataset was low. This study highlights different driving factors at low flows and during storm runoff events, and the need to measure at both time scales to better understand phage transport dynamics in surface water.

This study is focused on the metals’ pollution level in sediment core collected from Manora Picnic Point of Karachi coastal area Pakistan. The sediment was categorized in terms of pH, particle size, total organic carbon (TOC), calcium carbonate, and heavy metals, besides the determining the mineralogy composition of sediment. Metals were determined using proton-induced X-ray emission spectroscopy (PIXE) technique. The results of abundant and heavy metals in the sediment core indicated a significant upward enrichment, which could be the cause of discharge of industrial effluents and domestic wastewaters of Metropolitan Karachi into sea. The average geo-accumulation index values showed that sediments were moderately polluted with Co and Pb, and unpolluted for metals (Al, Ca Mg, Cr, Cu, Fe, K, Mn, Ni, Ti, V, and Zn). The pollution load index values indicate an increasing trend from bottom to top, which may be due to the influence of anthropogenic sources. According to the sediment quality guidelines of United States Environmental Protection Agency (USEPA), core sediment was heavily polluted with Ni and moderately polluted with Pb, Cu and Zn.

Surface sediment samples from Taihu Lake in China and its inflow rivers, along with two lake sediment core samples, were collected and analyzed for organophosphate esters (OPEs). The concentrations of total OPEs varied from 28.60 ng/g to 158.72 ng/g (median: 54.25 ng/g) in river surface sediment and from 62.57 ng/g to 326.84 ng/g (median: 86.37 ng/g) in lake sediment. Tributyl phosphate (TnBP) was the predominant compound in river surface sediment, and tris(2-butoxyethyl) phosphate was predominant in lake sediment. High contamination occurred in the north-west region, which was related to the high level of urbanization and high usage of OPEs. The sediment-water partition coefficients of OPEs (logKoc) were calculated, showing a significant correlation with logKow (p < 0.05). The concentration and composition of OPEs in two sediment cores varied due to the different sampling locations, with more OPE species found in the northern region than in the southern one. Principal component analysis and positive matrix factorization indicated that sewage discharges, vehicle emissions, and atmospheric deposition were the possible sources of OPEs in Taihu Lake sediments. Tris(1-chloro-2-propyl) phosphate, tris(2-chloroethyl) phosphate, and TnBP were the main OPEs causing ecological risks.

Radionuclide depth distribution in bottom sediments in deep-water zones of dam reservoirs, where no sediment mixing occurs, can be used to reconstruct time changes in particulate activity concentrations of radionuclides strongly bound to bottom sediments. This approach was used to analyze the 137Cs concentration profile in a bottom sediment core collected from Ogaki dam reservoir on the Ukedo River in the Fukushima Dai-ichi nuclear power plant contaminated zone in October 2019. The derived 137Cs particulate concentrations provided a basis for estimating the dissolved concentration and its temporal trend in the Ukedo River, using the mean value of the apparent 137Cs distribution coefficient. The reconstructed particulate and dissolved 137Cs concentrations and their temporal trends are consistent with monitoring data. The annual mean particulate and dissolved 137Cs wash-off ratios were also calculated for the period of eight years after the accident. Interestingly, the particulate 137Cs wash-off ratios for the Ukedo River at Ogaki dam were found to be similar to those for the Pripyat River at Chernobyl in the same time period after the accident, while the dissolved 137Cs wash-off ratios in the Ukedo River were an order of magnitude lower than the corresponding values in the Pripyat River. Both the particulate and dissolved 137Cs wash-off ratios in the Ukedo River declined faster during the first eight years after the FDNPP accident than predicted by the diffusional model, most likely, due to greater natural attenuation and, to some extent, remediation measures implemented on the catchments in Fukushima.

Sediment core samples from high tide lines and in submerged zones as well as surface water samples from eight beaches of Tenerife were analysed. Sampling was conducted over a period of one year in intervals of 5 weeks. The majority of particles were found in the high tide sediment (66%), followed by water samples (23%) and finally in sediment from submerged zones (11%). Regarding the particle amount per volume (items/L), accumulation in sediment samples was statistically higher compared to water samples. Mean values of items/L were higher in high tide sediments. In high tide and water samples, mostly white and transparent particles >1 mm were found. More than 70% were represented by fragments. In sediments from submerged zones, yellow and blue microparticles (

Dust storm variations over the past ~230 years were reconstructed on the northeast Loess Plateau using a sediment core from Lake Gonghai. The coarse component of the lake sediments (17.38–109.65 μm) was extracted using the grain size standard deviations method and could be used as a dust storm proxy. The reconstructed results suggest five dust storm peaks: in the 1810s, the late 1850s to the late 1880s, the late 1890s to the early 1920s, ~1950s to the early 1990s, and the late 2000s to the early 2010s. The 1950s–1990s had the highest frequency of dust storms over the past ~230 years, as a result of the combined effects of increased human activities, droughts, and strong winds. Before ~1950, the frequency of dust storms was influenced mainly by natural factors, such as drought events and high intensities of the Siberian High and the East Asian Winter Monsoon. After the 1950s, intensive human activity had a significant impact on dust storms, resulting in a relatively high frequency. However, because of a weakening trend in wind strengths resulting from global warming and ecological rehabilitation projects in North China, the frequency of dust storms has significantly decreased in the past two decades. This study highlights the significant effect of human activities on dust storm generation in Inner Asia and the variations in dust storms under global warming scenarios.

To understand siltation processes within the North Port of Incheon, Korea, this study estimated the sedimentation rate and then determined the dominant mechanisms for the siltation. The sedimentation rate was estimated by comparing bathymetric surveys adjusted with the dredged volume, and verified by the penetration depth of 11 gravity cores to the previous dredging surface. The average sedimentation rate was 64 cm/year but varied from 10 cm/year in the interior to about 100 cm/year at the entrance. To determine the dominant mechanisms for siltation, two ADCPs were deployed at the entrance and the interior end of the harbor over a month to estimate sediment flux. Detailed sediment transport processes were examined by two 13-h CTD profiling surveys near the entrance and interior end of the harbor. High siltation at the entrance is attributable to the influx of high turbidity water, the decrease of current velocity, and the formation of an eddy. Low sedimentation inside the harbor was attained by the slow settling of microflocs of about 20–30 mg/l concentration that are maintained regardless of time and space.

Redox-sensitive elements (uranium, molybdenum and cadmium) and productivity proxies (total organic carbon, calcium carbonate and phosphorous) were analysed to assess the importance of productivity on redox variation for the last ∼18 kyr in a sediment core off Cochin at a water depth of 280 m in the southeastern Arabian Sea. These proxies document a combination of higher productivity and intense suboxic conditions during the last deglaciation (∼18–13 kyr) and late Holocene (5.5 kyr to Present) versus lower productivity and less suboxic conditions between these intervals (∼13–5.5 kyr). The productivity and redox proxies behave similar to one another suggesting that the variations in productivity controlled the redox conditions. This relationship is supported by patterns during the last deglaciation, when a decrease in productivity at ∼16 kyr preceded improved deep water oxygenation by ∼14 kyr. Therefore, productivity changes were responsible for the development of reducing conditions in shallow waters in the southeastern Arabian Sea.

In past decades, China has experienced substantial economic growth and industrialization. However, the effects of vast development of China on Hg input to the nearby oceans are still unclear. In this study, four representative 210Pb-dated sediment cores were collected in the central and southern part of Bohai sea to investigate vertical changes of Hg contents and explore the relationship between the Hg deposition and pollution history in this region utilizing a large amount of information available. The results indicated that Hg median concentrations of sediment core B62, B66, JQ17 and HZ24 were 0.043 mg/kg, 0.054 mg/kg, 0.033 mg/kg and 0.018 mg/kg respectively, among which, B66 in Yellow river estuary and B62 in central part of Bohai Sea had higher concentrations and HZ24 in Bohai Strait had a lower concentration. 210Pb profile appeared as a three segments model in the core B62, but as many steps of decay with depth in B66. For HZ24, 210Pb activity only fluctuated with depth without any discernible trend. Sedimentary rates of these cores decreased as follows: B66＞B62＞JQ17＞HZ24. Vertical distributions of Hg concentrations in sediment cores were totally different from each other. Hg concentrations in sediment core B62 experienced an initial fluctuation followed by a decreasing trend, while sediment core HZ24 almost showed the uniform decreasing trends from the surface to the bottom. There were three segments of variation in sediment cores JQ17: initial fluctuation followed by an obviously decreasing tendency and then a converted variation from surface to bottom. Hg contents changes in core B62 might reflect the additive effects from atmospheric deposition at a larger scale and the river-delivered sediment accumulation, while Hg vertical changes in B66 mainly had a close relationship with the input of Yellow river. The converted variation at the bottom section in sediment cores JQ17 was inferred to have some relationship with the Chengbei platform construction in the corresponding periods.

This paper presented the historical data on the temporal trends of polybrominated diphenyl ethers (PBDEs) in the sediment cores collected from the Huaihe River, Yellow River and Chaohu Lake, China. Among the 40 targeted PBDE congeners, only 10, 6, and 9 of them were detected respectively in the samples from the Huaihe River, Yellow River and Chaohu Lake. On average, the total PBDEs concentrations in sediments were highest in Chaohu Lake followed by the Huaihe River and the Yellow River. As compared to other PBDE congeners, BDE-209 had higher concentrations and detection rates. The similar down core variation between PBDEs and total organic carbon (TOC) suggests that TOC is an important factor influencing PBDEs distribution in the sediments. The total PBDEs concentrations showed an increasing trend from bottom to upper sediments before a decreasing trend in the topmost sediments. The rapid urbanization and industrialization of these regions in recent decades may cause the historically increasing concentrations of sedimentary PBDEs, especially BDE-209. The decreasing PBDEs concentrations in topmost sediments was probably related to the strict environmental policies at present.

Lakes close to the limit of East Asia summer monsoon (EASM) are sensitive to the climate changes, which record significant information about environmental changes and human activities. One sediment core was collected from Dali Lake in north EASM margin of China and high-resolution multi-proxies are analyzed. The constant rate of supply (CRS) model based on 137Cs and 210Pb contents is established and provides a detail history of EASM variability and environmental changes over past ~168 years. The period from ~1847 to 1900 AD was characterized by the steady values of total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC) and C/N and decrease in δ13Corg values reflected slightly enhanced EASM. The period between ~1901 to 1944 AD, δ13Corg values indicated EASM first decrease and then increase. The gradually increased TN, TP and TOC values and the decreased C/N ratios indicated the shrink of the lake area caused by the higher evaporation and autochthonous OM increased. From ~1945 to 2015 AD, the increased values in TN, TP and TOC may be mainly caused by the shrink of the lake area and the enhanced human activities, and δ13Corg values suggested a fluctuant EASM in this period. Mercury (Hg) element in Dali Lake sediments gradually increased since 1847 AD while it was constant in the interval of ~1944−1959 AD and then kept increasing, which may be caused by the increased Hg content in atmosphere from Europe and other industrial area. The EASM variability over past ~168 years showed the trends were similar to EASM records in other regions of China. Furthermore, our findings indicated that the variability of the EASM was forced by changes in oceanic-atmospheric circulation interaction.

A radionuclide-dated (210Pb and 137Cs) sediment core collected from Hampstead Pond No. 1, a North London lake, was used to provide novel data on the historical accumulation of microplastic waste in the urban environment. Microplastics were extracted from sediments by sieving and dense-liquid separation. Fibres of anthropogenic origin dominated the assemblage. Microplastics were first identified by microscopy before Raman spectroscopy of selected particles was used to determine the composition of synthetic polymers and dyes. Polystyrene microplastic particles were identified, in addition to synthetic fibres of polyacrylonitrile, polyvinyl chloride and fibres containing synthetic dyes. Concentrations of total microplastics in the sediment samples ranged from detection level to 539 particles per kilogram of dried sediment. Proliferation of microplastics is evident in the core from the late 1950s to the present. Relatively low numbers of particles were found in older sediments, comparable to laboratory blanks, highlighting the difficulty of extending a plastic chronostratigraphy back to the early twentieth century. This study shows that, with optimisation, routine extraction of microplastics from radionuclide-dated lake sediments can add an important temporal perspective to our understanding of microplastics in aquatic systems.

A paleoecological study was performed on a sediment core recovered from a former artificial lake – the Reedbed of Sic near Cluj-Napoca, Romania – in order to explore the history of water management...

International audience; For ecological and economic issues, evaluating the environmental fate of dissolved and suspended matter in catchments and river ecosystems still remains a challenge for the preservation and management of natural resources. Models are useful tools and may help to cope with this challenge, and especially to define the relationships between the state of natural systems and land and river management/uses. As it is difficult -even impossible- to carry out experiments on natural systems such as catchments, models are also useful to test hypotheses about the underlying processes acting on dissolved and suspended losses. We propose a innovative approach to achieve these objectives. By coupling environmental indicators and lumped modeling, this study aims to develop a conceptual and general framework to evaluate and test the functions that drive particulate and dissolved matter flows at the catchment and landscape scales, while respecting the constraint of parsimony for the number of model parameters. Calculated suspended matter (SM) and soluble reactive phosphorus (SRP) losses agreed well with field data. 210Pbex (excess Pb) activities in core sediments were also compared to those of 210Pbex calculated from the filling of the reservoir. Our models are parsimonious and this does not impair their accuracy in reproducing recorded outflows or evaluating the sedimentation processes associated to particulate outflows. Considering the adequacy of our models, we validate the hypothesis that river bank erosion and water table behavior are the driving processes that govern losses of particulate and solute forms of P, in the studied extensive agriculture conditions.

This study evaluated the sources of Zn pollution in Tokyo Bay, Japan, on the basis of δ66Zn in a sediment core. The Zn concentration in sediments in the 1980s-2000s was considerably higher than the background concentration, suggesting that there remain important sources of Zn in the bay. The δ66Zn (+0.51‰) of anthropogenic Zn estimated in the core was significantly higher than those (approximately –0.1‰ - +0.2‰) of treated water from sewage treatment plants and vehicle-related sources. A large number of electroplating plants are located in Tokyo areas. It is assumed that Zn in effluents from electroplating operations is isotopically heavier owing to a negative isotopic effect on Zn electroplating. This tends to support the hypothesis that river bottom sediments, which were contaminated with Zn in the untreated effluents from electroplating plants in the past, are the principal sources of anthropogenic Zn in Tokyo Bay in the 1980s-2000s.

Concentration and transport pathways of plutonium in the marine environment play an important role to assess the radioactivity as well as the ecological influence. In order to obtain the results of plutonium concentration from main sources along the coast of Guangxi, surface soil samples and sediment core were analyzed by ICP-MS. The results indicated that the concentration of 239+240Pu in the surface soils and sediments are in the range of 0.136–0.272 and 0.088–0.469 Bq/kg, respectively. The ratios of 240Pu/239Pu are in the range of 0.171–0.198, which coincides with the value of contribution of the global fallout. The sedimentation rate of Sanniang Bay (sample no. SN2) were measured by excess 210Pb, 137Cs and 239+240Pu, respectively.

The occurrence of 209 PCB congeners was determined in a sediment core dated between 1930 and 2019 from Lake Biwa, a typical temperate monomictic lake in Japan. Concentrations of total PCBs ranged from 5.3 to 48 ng/g dry weight (dw), showing a highest peak at the 1960s to 1970s. The temporal trend of total PCBs in this sediment core generally matched with Japanese PCB production and emission pattern (i.e., increasing from the 1950s, peaking at 1970, and gradually decreasing since 1972). The vertical PCB profiles in our core were affected by physical mixing and bioturbation. By using a detailed and comprehensive analytical method, we have found elevated concentrations and special historical profiles of several congeners such as CB-7, -11, -47/48/75, -51, -68, and -209, which are still rarely included in routine PCB analysis. Some tetra-CB congeners like CB-47/48/75, -51, and -68 showed their concentration peaks at the early 2010s, which may be unintentionally produced during polymer manufacturing processes. PCB homolog- and congener-specific profiles in our sediment core samples have experienced weathering with higher proportions of penta- and hexa-CBs as compared to the Kanechlor usage pattern (i.e., dominated by tri- and tetra-CBs). Both intentional (i.e., technical mixtures) and unintentional (e.g., PCB-containing polymers and pigments) sources of PCBs were suggested from congener-specific analysis.

The development of rapid and efficient analytical method for the determination of legacy and current-use brominated flame retardants (BFRs) has been performed due to environmental concern related to these pollutants. In the present study, we used an automated clean-up device equipped with pre-packed micro-column sets (containing sulfuric acid impregnated silica gel and silver-modified alumina) to develop an effective purification method for polybrominated diphenyl ethers (PBDEs), pentabromoethylbenzene, hexabromobiphenyl, and decabromodiphenyl ethane (DBDPE) in sediment extracts. Matrix-spiked sediments (n = 6) and the Standard Reference Material® 1944 samples (n = 6) were tested. Our method showed acceptable accuracy, repeatability, and sensitivity for almost all the target compounds with reduced processing time, labor requirement, and solvent amounts as compared to conventional clean-up method (e.g., sulfuric acid treatment and self-packed chromatographic columns). The validated method was applied to sediment core samples (n = 16) collected in 2019 from Lake Biwa, the largest lake in Japan. PBDEs were detected in sediment samples of 0–13 cm depth (dated between 1990 and 2019) at relatively low concentrations (median 5.7; range 2.6–9.4 ng/g dry weight). PBDE profiles were dominated by BDE-209, which accounted for 91 ± 10% of total PBDEs. Among other BFRs, only DBDPE was found in sediment layers of 0–9 cm depth (deposited between 2005 and 2019). DBDPE concentrations ranged from 0.43 to 1.6 (median 0.71) ng/g and showed increasing trend toward shallower depths.

Dating recent sediment archives (137Cs) emitted during thermonuclear bombs testing (~1950 - ~1980) and nuclear accidents (1986 and 2011) was generally used for identifying sediment sources or for establishing sediment core chronology based on discrete time markers. Although this method was widely used during the last several decades, there is a lack of structured and comprehensive worldwide synthesis of radiocaesium fallouts. The current literature overview was based on 573 articles published between 1977 and 2020, reporting the collection of 1351 individual dated sediment cores. This synthesis led to the identification of the worldwide distribution of discrete time markers associated with the thermonuclear bomb testing peak in 1963, the Chernobyl fallout, the Fukushima fallout, as well as the identification of at least 25 events induced by local accidents or nuclear tests (e.g. Sellafield, la Hague accidents, Chinese nuclear tests).With a growing number of studies focusing on the analysis of recent sediment cores and the increasing interest in sediment fingerprinting techniques, this spatialized synthesis provides a unique worldwide referential for identifying the distribution of the 137Cs sources at global scale. It also outlines the main questions that would deserve attention in future research perspectives and the regions where 137Cs fallouts investigations should be conducted in priority.

We assessed the contributions of Cu smelting and Asian dust influx to metal(loid) pollution over the last century based on metal(loid) concentrations, Pb isotope ratios, and 210Pb dating of sediments from Gunsan Reservoir, South Korea. During the pre-industrial period (1827–1936), heavy metal pollutants were predominantly geogenic. Local smelting activity was dominant between 1936 and 2008. Between 1936 and 1971, Cu and Pb contamination was not significant, with contributions from smelting activities accounting for

The study deals with the spatio-temporal distribution of heavy metals in the sediments of Chagan lake, Northeast China. The pollution history of heavy metals is studied simultaneously through the 210Pb dating method by analyzing the characteristic of As, Hg, Cd, Cr, Ni, Cu, Pb, and Zn concentration-depth profiles. The potential ecological risk index (RI) and geo-accumulation index (Igeo) were used to evaluate the contamination degree. Principal component analysis (PCA), based on the logarithmic transformation and isometric log-ratio (ilr) transformed data, was applied with the aim of identifying the sources of heavy metals. The element concentrations show that the heavy metals are enriched in the surface sediment and sediment core with a varying degree, which is higher in the surficial residue. The results of Igeo indicate that the Cd and Hg in the surface sediment have reached a slightly contaminated level while other elements, uncontaminated. The results of RI show that the study area can be classified as an area with moderate ecological risk in which Cd and Hg mostly contribute to the overall risk. For the sediment core, the 210Pb dating results accurately reflect the sedimentary history over 153 years. From two evaluation indices (RI and Igeo) calculated by element concentration, there is no contamination, and the potential ecological risk is low during this period. The comparative study between raw and ilr transformed data shows that the closure effect of the raw data can be eliminated by ilr transformation. After that, the components obtained by robust principal component analysis (RPCA) are more representative than those obtained by PCA, both based on ilr transformed dataset, after eliminating the influence of outliers. Based on ilr transformed data with RPCA, three primary sources could be inferred: Cr, Ni, As, Zn, and Cu are mainly derived from natural sources, the main source of Cd and Hg are associated with agricultural activities and energy development, as for Pb, it originated from traffic and coal-burning activities, which is consistent with the fact that the development of tourism, fishery, and agriculture industries has led to the continuous increasing levels of anthropogenic Pb in Chagan Lake. The summarized results and conclusions will undoubtedly enhance the governmental awareness of heavy metal pollution and facilitate appropriate pollution control measures in Chagan Lake.

Summary To follow climate change in sediment cores it is important to now how quick a biomarker reacts to climate change. Here we investigated a sediment core from Lake Van retrieved during an ICDP campaign in 2021. We compare compound specific hydrogen isotopes measurements on biomarkers, i.e. long-chain n-alkanes and alkenones to understand which biomarker reacts first to, in this case, the water cycle (precipitation, evaporation) in the Eastern Turkey area.

This work reports the first high-resolution deposition records of anthropogenic uranium (236U and 233U) in a sediment core taken at the continental slope of the Philippine Sea off Mindanao Island in the equatorial northwest Pacific Ocean. Two notable peaks were observed in both profiles of 236U and 233U concentrations, with a narrower peak in 1951–1957 corresponding to close-in Pacific Proving Grounds (PPG) signal, and a broader peak in 1960s–1980s corresponding to the global fallout from nuclear weapons testing. 236U and 233U areal cumulative inventories in the studied sediment core are (2.79 ± 0.20) ∙ 1012 atom ∙ m−2 and (3.12 ± 0.41) ∙ 1010 atom ∙ m−2, respectively, about 20–30% of reported 233U and 236U inventories from the direct global fallout deposition. The overall 233U/236U atomic ratios obtained in this work vary within (0.3–3.5) ∙ 10−2, with an integrated 233U/236U atomic ratio of (1.12 ± 0.17) ∙ 10−2. The contribution from global fallout and close-in PPG fallout to 236U in the sediment core is estimated to be about 69% and 31%, respectively. We believe the main driving process for anthropogenic uranium deposition in the Philippine sediment is continuous scavenging of dissolved 236U from the surface seawater by sinking particles.

The growing use of plastic and their indiscriminate disposal into the environment has resulted in the accumulation of huge quantities of microplastic (MP) in the marine environment. Several studies have investigated the pathways of MPs reaching marine environments and a few have begun looking at their inventories in sediment profiles. Recent estimates suggest between 70 and 90% of the MP particles are accumulated into sediment profiles. This paper reviews MPs in sediment cores, and the methods used for chronological reconstruction to provide evidence to link the plastic usage and MP inventories over time. In one example, a 210Pb dated sediment core from Kuwait Bay revealed 0.1 MPs g−1 of sediment deposited in approximately 1951 and 0.5 MPs g−1 in sediment from 2009 indicating a progressively increasing presence in recent sediments. The review also highlights the issue of very large spatio-temporal variation in MP concentrations, indicating the limitation of a snapshot study especially when dealing with the surface sediments; and it demonstrates the relevance of using sediment cores for a better assessment of MP input and inventories in the marine environment. It is proposed that MP sediment data should be reported as N m−2 year−1 or g m−2 year−1, and cores preferably dated using 210Pb, and supported by at least one other stratigraphic marker to enhance the usefulness of these datasets, since 210Pb can reliably date sediments as old as 100 years, a time-span which extends well beyond the time plastic production began. The anomalies in data processing and reporting in terms of number per kg of sediment or per cm2/m2 should be addressed essentially by adopting a standardized protocol.

International audience; Brominated flame retardants (BFRs) are anthropogenic compounds that are ubiquitous in most manufactured goods. Few legacy BFRs have been recognised as persistent organic pollutants (POPs) and have been prohibited since the 2000s. However, most BFRs continue to be used despite growing concerns regarding their toxicity; they are often referred to as novel BFRs (nBFRs). While environmental contamination due to chlorinated POPs has been extensively investigated, the levels and spatiotemporal trends of BFRs are comparatively understudied. This study aims to reconstruct the temporal trends of both legacy and novel BFRs at the scale of a river corridor. To this end, sediment cores were sampled from backwater areas in four reaches along the Rhône River. Age-depth models were established for each of them. Polychlorinated biphenyls (PCBs), legacy BFRs (polybrominated diphenyl ethers - PBDEs, polybrominated biphenyls - PBBs and hexabromocyclododecane - HBCDDs) and seven nBFRs were quantified. Starting from the 1970s, a decreasing contamination trend was observed for PCBs. Temporal trends for legacy BFRs revealed that they reached peak concentrations from the mid-1970s to the mid-2000s, and stable concentrations by the mid-2010s. Additionally, individual concentrations of nBFRs were two to four orders of magnitude lower than those of legacy BFRs. Their temporal trends revealed that they appeared in the environment in the 1970s and 1980s. The concentrations of most of these nBFRs have not decreased in recent years. Thus, there is a need to comprehend the sources, contamination load, repartition in the environment, and toxicity of nBFRs before their concentrations reach hazardous levels.

The interest in UV filters&rsquo, occurrence in the environment has increased since they were recognized as &ldquo, emerging contaminants&rdquo, having potentially adverse impacts on many ecosystems and organisms. Increased worldwide demand for sunscreens is associated with temperature anomalies, high irradiance, and changes in the tourist market. Recently, it has been demonstrated that personal care products, including sunscreens, appear in various ecosystems and geographic locations causing an ecotoxicological threat. Our goal was to determine for the first time the presence of selected organic UV filters at four beaches in the central Pomeranian region in northern Poland and to assess their horizontal and vertical distribution as well as temporal variation at different locations according to the touristic pressure. In this pioneering study, the concentration of five UV filters was measured in core sediments dredged from four exposed beaches (Darłowo, Ustka, Rowy, and Czołpino). UV filters were detected in 89.6% of collected cores at detection frequencies of 0&ndash, 22.2%, 75&ndash, 100%, 0&ndash, 16.7%, and 2.8&ndash, 25% for benzophenone-1 (BP-1), benzophenone-2 (BP-2), benzophenone-3 (BP-3), and enzacamene (4-MBC), respectively. In terms of seasonality, the concentration of UV filters generally increased in the following order: summer &gt, autumn &gt, spring. No detectable levels of 3-BC (also known as 3-benzylidene camphor) were recorded. No differences were found in the concentration of UV filters according to the depth of the sediment core. During the summer and autumn seasons, all UV filters were detected in higher concentrations in the bathing area or close to the waterline than halfway or further up the beach. Results presented in this study demonstrate that the Baltic Sea coast is not free from UV filters. Even if actual concentrations can be quantified as ng&middot, kg&minus, 1 causing limited environmental threat, much higher future levels are expected due to the Earth&rsquo, s principal climatic zones shifting northward.

In recent years, concern about the release of anthropogenic organic micropollutants referred to as contaminants of emerging concern (CECs) has been growing. The objective of this study was to find potential CECs by means of an analytical screening method referred to as comprehensive target analysis with an automated identification and quantification system (CTA-AIQS), which uses gas and liquid chromatography combined with mass spectrometry (GC-MS and LC-QTOF-MS). We used CTA-AIQS to analyze samples from a sediment core collected in Beppu Bay, Japan. With this method, we detected 80 compounds in the samples and CTA-AIQA could work to useful tool to find CECs in environmental media. Among the detected chemicals, three PAHs (anthracene, chrysene, and fluoranthene) and tris(isopropylphenyl)phosphate (TIPPP) isomers were found to increase in concentration with decreasing sediment depth. We quantified TIPPP isomers in the samples by means of targeted analysis using LC-MS/MS for confirmation. The concentration profiles, combined with previous reports indicating persistent, bioaccumulative, and toxic properties, suggest that these chemicals can be categorized as potential CECs in marine environments.

In this study, the concentrations of seven heavy metals (Cr, Ni, Cu, Zn, As, Hg, and Pb) and Pb isotope in a sediment core from the Shuanglong reservoir, Southwestern China, were investigated. Based on the constant rate of supply (CRS) model, the age span of a 60 cm sediment sample was determined to range from the years 1944 to 2015. Combined with chronology and heavy metal content, the evolution of the sources and pollution levels of heavy metals showed a changing trend composed of various stages. The sources of heavy metals transitioned from natural origins in 1944&ndash, 1964 to industrial origins in 1965&ndash, 2004. The subsequent reduction in heavy metal content was mainly due to the vigorous implementation of environmental protection policies from 2005 to 2012. In recent years (2013&ndash, 2015), the heavy metal content has increased due to frequent human activity. Principal component analysis (PCA), correlation analysis, and the coefficient of variation (CV) analysis indicated that Cr, Ni, Cu, Zn, and As were derived from natural processes, Pb mainly came from automobile manufacturing, and Hg was mainly from industrial sources. The values of the geo-accumulation index (Ig), single pollution index (Pi), and single potential ecological risk index (Er) showed that the contamination of Hg and Pb was slight to moderate. Moreover, the values of the potential ecological risk index (RI), pollution load index (PLI), and Nemerow index (PN) indicated that the Shuanglong reservoir is under low ecological risk.

The aim of present study was to evaluate temporal changes in the distribution of polycyclic aromatic hydrocarbons (PAHs) in the estuary of the Itapicuru (Brazil). A sediment core was sampled in the study area. Concentrations of the 16 priority PAHs were analyzed using gas chromatography coupled to a mass spectrometry. A gas flow proportional counter was used to estimate the sedimentation rate through the determination of 210Pb. Granulometric fractions and total organic carbon (TOC) concentrations were also evaluated. Concentrations of TOC and PAHs ranged from 0.65 to 2.51% and 1.98 to 43.1 ng g−1 (dry weight), respectively. Significant correlations (p

Made available in DSpace on 2020-12-12T02:27:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Sediments geochemical data from Araxá city, Minas Gerais State, Brazil, have provided new insights on the pollutants inputs in different drainage systems of Araxá city, Minas Gerais State, Brazil. The sediments profiles (6) provided from a lake (Grand Hotel) and streams (Sal, Areia, Fundo, and Feio). The local municipality uses some waters (Areia, Fundo, and Feio streams) in water-supply systems. Because of the Brazilian environmental agency does not establish concentration guidelines for several heavy metals occurring in freshwater sediments, the values reported in this paper were compared with limits proposed elsewhere. Enrichment Factor (EF) values of 20–40 (very high enrichment) and EF > 40 (extremely high enrichment) were found for Ba (in two sediment core), Nb (in three sediment core) and Se (in four sediment core). The 210Pb chronological method was useful for tracking some major events that occurred in the history of Araxá city, showing concentration peaks around 1962 and 1993 for BaO, Nb2O5, Fe2O3, P2O5, SO3, SrO and CeO2 and around 1972 and 1999 for SeO2. Instituto de Geociências e Ciências Exatas-IGCE Universidade Estadual Paulista-UNESP, Av. 24-A No. 1515, P.O. Box 178, CEP, São Paulo Instituto de Geociências e Ciências Exatas-IGCE Universidade Estadual Paulista-UNESP, Av. 24-A No. 1515, P.O. Box 178, CEP, São Paulo CNPq: 301992/2016–9 CNPq: 400700/2016–6

The entirety of the sediment bed in lake Tyrifjorden, Norway, is contaminated by per- and polyfluoroalkyl substances (PFAS). A factory producing paper products and a fire station were investigated as possible sources. Fire station emissions were dominated by the eight carbon perfluoroalkyl sulfonic acid (PFSA), perfluorooctanesulfonic acid (PFOS), from aqueous film forming foams. Factory emissions contained PFOS, PFOS precursors (preFOS and SAmPAP), long chained fluorotelomer sulfonates (FTS), and perfluoroalkyl carboxylic acids (PFCA). Concentrations and profiles in sediments and biota indicated that emissions originating from the factory were the main source of pollution in the lake, while no clear indication of fire station emissions was found. Ratios of linear-to branched-PFOS increased with distance from the factory, indicating that isomer profiles can be used to trace a point source. A dated sediment core contained higher concentrations in older sediments and indicated that two different PFAS products have been used at the factory, referred to here as Scotchban and FTS mixture. Modelling, based on the sediment concentrations, indicated that 42e189 tons Scotchban, and 2.4e15.6 tons FTS mixture, were emitted. Production of paper products may be a major PFAS point source, that has generally been overlooked. It is hypothesized that paper fibres released from such facilities are important vectors for PFAS transport in the aquatic environment. © 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).