Search

• A novel blended algorithm was proposed to remotely observe lake POC across China. • POC concentrations in 450 large lakes were first mapped using OLCI/Sentinel-3 data. • Lake POC concentration across China was low in the west and high in the east. Remote sensing monitoring of particulate organic carbon (POC) concentration is essential for understanding phytoplankton productivity, carbon storage, and water quality in global lakes. Some algorithms have been proposed, but only for regional eutrophic lakes. Based on in-situ data (N = 1269) in 49 lakes across China, we developed a blended POC algorithm by distinguishing Type-I and Type-II waters. Compared to Type-I, Type-II waters had higher reflectance peak around 560 nm (>0.0125 sr−1) and mean POC (4.65 ± 4.11 vs. 2.66 ± 3.37 mg/L). Furthermore, because POC was highly related to algal production (r = 0.85), a three-band index (R 2 = 0.65) and the phytoplankton fluorescence peak height (R 2 = 0.63) were adopted to estimate POC in Type-I and Type-II waters, respectively. The novel algorithm got a mean absolute percent difference (MAPD) of 35.93 % and outperformed three state-of-the-art formulas with MAPD values of 40.56–76.42 %. Then, the novel algorithm was applied to OLCI/Sentinel-3 imagery, and we first obtained a national map of POC in 450 Chinese lakes (> 20 km2), which presented an apparent spatial pattern of "low in the west and high in the east". In brief, water classification should be considered when remotely monitoring lake POC concentration over a large area. Moreover, a process-oriented method is required when calculating water column POC storage from satellite-derived POC concentrations in type-II waters. Our results contribute substantially to advancing the dynamic observation of the lake carbon cycle using satellite data. [Display omitted] [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate the genetic etiology of epilepsy in a cohort of Chinese children.Methods: Targeted next-generation sequencing (NGS) was performed for 120 patients with unexplained epilepsy, including 71 patients with early-onset epileptic encephalopathies, and 16 patients with Dravet syndrome (including three patients with a Dravet-like phenotype) but without SCN1A pathogenic variants.Results: Pathogenic variants of 14 genes were discovered in 22 patients (18%). A de novo KCND3 pathogenic variant (c.1174G > A, p.Val392Ile) was identified in a boy with refractory epilepsy, psychomotor regression, attention deficit, and visual decline. Pathogenic variants in other coding genes were excluded via whole exome sequencing. This KCND3 variant was previously confirmed to be pathogenic by Giudicessi, et al. However, the clinical profile was different: sudden death at 20 years old without any medical history of neurological disorders, nor with any diseases typically caused by KCND3 pathogenic variants such as Brugada syndrome, spinocerebellar ataxia type 19/22 or ataxia accompanied by epilepsy. This indicates that we have identified a new KCND3 phenotype. In addition, we also uncovered a GRIN1 pathogenic variant and a novel HCN1 pathogenic variant in the Dravet cohort.Conclusion: Our study highlights the significant utility of NGS panels in the genetic diagnosis of pediatric epilepsy. Our findings indicate that KCND3 pathogenic variants may be responsible for a wider phenotypic spectrum than previously thought, by including childhood epileptic encephalopathy. Furthermore, this study provides evidence that GRIN1 and HCN1 are candidate genes for Dravet and Dravet-like phenotypes. [ABSTRACT FROM AUTHOR]

Riverine organic carbon (OC) transport plays a role in regulating terrestrial and marine carbon pools and deteriorating coastal water quality. However, long-term OC transport in Asian rivers and its diffusion in marginal seas have remained unreported. This study reported the spatiotemporal variations in OC resources for Hong Kong waters, China, based on monthly monitoring data collected at 82 river stations and 94 ocean sites during 1986–2020. The station-based riverine OC varied spatially and was generally high, with a mean value of 1.4–52.0 mg/L. Moreover, along with improving water quality, OC at 97.6% of the river stations decreased during 1986–2020; overall, sewage treatment accounted for 83.4% of the exponential decrease in riverine OC (R 2 = 0.68, p < 0.01). However, the reduction in riverine OC accounted for only 10.4% of the reduction in the marine five-day biochemical oxygen demand (BOD 5), which occurred at 70.2% of the ocean sites, especially those closest to the shore. The linear reduction in the marine BOD 5 (R 2 = 0.24, p < 0.01) was mainly attributed to reduced OC input from the adjacent Pearl River (61.9%) and decreases in phytoplankton growth (19.0%). These results indicated that sewage treatment improved water quality and decreased OC resources in Hong Kong waters, which can serve as a sustainable development model for other coastal cities. This study has important implications for mitigating organic pollution in the context of human efforts to manage the water environment. • Sewage treatment decreased OC resources in waters between 1986 and 2020. • Riverine OC input primarily influenced organic pollution in nearshore waters. • The sustainable management of water resources in Hong Kong is exemplary. [ABSTRACT FROM AUTHOR]

Abstract: ZnMoO4 with a rhombus sheet or flower-like structure, α-ZnMoO4 and needle-like ZnMoO4·0.8H2O were successfully synthesized by simple hydrothermal crystallization processes with citric acid. ZnMoO4·0.8H2O was easily synthesized in a shorter reaction time (2h) at a higher reactant concentration. It gradually transformed into ZnMoO4 with a monoclinic wolframite tungstate structure with an increased reaction time, and pure ZnMoO4 was obtained with a longer reaction time (8h). Citric acid (CA) played an important role in controlling the morphology of the as-obtained molybdates. The α-ZnMoO4 and ZnMoO4 were synthesized by heating ZnMoO4·0.8H2O at 130°C for 4h and 8h, respectively, under hydrothermal conditions. With transforming of ZnMoO4·0.8H2O to α-ZnMoO4 and further to ZnMoO4, the needle-like crystals gradually disappeared and were transformed into crystals with rhombus sheet morphology and then further to pentacle or flower-like crystals that can be ascribed to continuous splitting and growing of the rhombus sheets. [Copyright &y& Elsevier]

Dissolved organic carbon (DOC) in lakes serves as a substrate for heterotrophic bacterial growth, a regulator of the global carbon cycle, and a light absorption agent. DOC in eutrophic lakes is greatly influenced by phytoplankton phenology and terrigenous input by rivers. Therefore, it is necessary and significant to dynamically monitor the concentration, storage, and riverine exchange flux of DOC. By using in-situ DOC measurements from 2004 until 2018 (N = 2019), a machine learning algorithm, namely, a multilayer back-propagation neural network (MBPNN) model, was developed in this work to improve the remote sensing estimation of DOC concentrations in eutrophic Lake Taihu. The model yielded a mean estimation error of 15.14% for the testing dataset. The monthly mean DOC concentration significantly increased from 2003 to 2018 (N = 192, p < 0.01). High DOCs were observed in lake bays with high chlorophyll a (Chl-a) levels, and phytoplankton growth explained more than 50% of the monthly DOC variations. Then, given the evenly mixed DOC in the water column on the monthly and annual scales, we further estimated the monthly mean DOC storage in the lake from 2003 until 2018 and DOC fluxes (input and output) due to rivers during 2008–2018. Although the mean net riverine DOC input (50.56 ± 32.22 × 103 t C) was approximately 5.2 times the average DOC storage (9.73 ± 1.23 × 103 t C), phytoplankton growth controlled DOC variations, which indicated that much terrigenous DOC was transformed into other carbon forms after entering Lake Taihu. This study verified the feasibility of remote sensing of DOC (surface concentration, storage, and riverine exchange flux) in eutrophic lakes. • Machine learning improved the remote sensing of DOC in eutrophic Lake Taihu. • DOC variations in the Lake Taihu were controlled by phytoplankton growth. • Net DOC input from rivers was ~5.2 times the DOC storage during 2008–2018. [ABSTRACT FROM AUTHOR]

Abstract Suspended particulate matter (SPM) is generally divided into inorganic (SPIM) and organic (SPOM) parts; they come from different sources, and have different impacts on the optical properties and/or water quality of lake. However, in a specific remote sensing process, they are not retrieved separately. Using in-situ data of 59 lakes along the middle and lower reaches of the Yangtze River (MLR-YR) in dry season (April) and wet season (August) in 2012, we first studied the absorption properties and sources of different SPM. On this basis, we proposed a workflow for simultaneously estimating SPIM and SPOM from satellite data. Our results are as follows: Bio-optical compositions of SPM in these eutrophic shallow lakes tempo-spatially varied greatly and were dominated by human-induced eutrophication. Phytoplankton contributed 18.42 ± 18.92% of SPIM and 26.22 ± 19.24% of SPOM in April 2012, but 30.4 ± 23.41% of SPIM and 47.03 ± 18.1% of SPOM in August 2012. The trophic state index explained 42.84% of SPOM variation in April 2012, and 54.64% in August 2012. Moreover, there were strong linear relationships between SPIM concentration and non-algal particle absorption coefficient (Pearson's r = 0.73 ; p < 0.01) and between SPOM concentration and phytoplankton absorption coefficient (r = 0.76 ; p < 0.01). Based on these results, SPIM and SPOM concentrations in the lakes along the MLR-YR could be retrieved from OLCI/Sentinel-3A satellite data, respectively. This study has a great significance for real-time monitoring and managing aquatic environment in various eutrophic and/or shallow lakes as a group. Graphical abstract Unlabelled Image Highlights • Lakes along the middle and lower reaches of Yangtze River were seriously eutrophic. • Suspended particle compositions were dominated by human-induced eutrophication. • Bio-optical compositions of suspended particles differed by trophic state index. • Monitoring suspended particle compositions using satellite data was achievable. [ABSTRACT FROM AUTHOR]

Abstract: Pyrochlore-type K2Ta2O6 compound cannot be obtained by a conventional solid-state reaction. Here, we report the synthesis of K2Ta2O6 and tetragonal tungsten bronze (TTB)-type K6Ta10.8O30 nanopowders using a facile and low-cost sol–gel method at low temperature. The as-prepared samples were characterized by XRD, TG-DSC, FESEM, UV–vis diffuse reflectance spectrum and XPS. The compound K2Ta2O6 was formed at 700°C and reached complete crystallization at 750°C, and decomposed into pure K6Ta10.8O30 with the volatilization of K2O at 900°C. The transformation of K2Ta2O6 to K6Ta10.8O30 is reported for the first time. The band gap of the pure K2Ta2O6 and K6Ta10.8O30 samples was found to be about 4.16 and 3.63eV, respectively. The as-prepared K2Ta2O6 sample exhibited an efficient photocatalytic activity for the decomposition of azo dye acid red G (ARG) and 4-nitrophenol (4-NP, a typical persistent organic pollutant) solution under UV irradiation. According to the experimental results, the mechanism of the photocatalytic reaction over K2Ta2O6 was discussed. [ABSTRACT FROM AUTHOR]

Abstract: Sr6Bi2O9 powders were synthesized by a sol–gel method using Bi(NO3)3·5H2O and Sr(NO3)2 as the starting materials and were characterized by X-ray diffraction (XRD), UV–vis diffuse reflectance spectrum (UV–vis DRS), Fourier transform infrared (FT-IR) spectrum and Raman spectrum. The as-prepared Sr6Bi2O9 powders showed an efficient photocatalytic activity in the decomposition of 4BS dye (a widely used azo dye) and 4-nitrophenol (4-NP, a priority pollutant) under visible light irradiation (λ >400nm). TA-PL analysis reveals that HOthe dominant photooxidant. The radical scavengers experiments indicated that the main active species was O2 − in the photocatalytic degradation of dye under visible irradiation. A possible photodegradation mechanism of organic pollutants by the visible light driven Sr6Bi2O9 was discussed. [Copyright &y& Elsevier]

Sphingolipids (SPLs) represent a highly diverse and structurally complex lipid class. The discussion of SPL metabolism-related issues is of importance in understanding the neuropathological progression of Alzheimer's disease (AD). AD is characterized by the accumulation of extracellular deposits of the amyloid β-peptide (Aβ) and intraneuronal aggregates of the microtubule-associated protein tau. Critical roles of Aβ oligomer deposited and ganglioside GM1 could be formed as "seed" from insoluble GAβ polymer in initiating the pathogenic process, while tau might also mediate SPLs and their toxicity. The interaction between ceramide and α-Synuclein (α-Syn) accelerates the aggregation of ferroptosis and exacerbates the pathogenesis of AD. For instance, reducing the levels of SPLs can mitigate α-Syn accumulation and inhibit AD progression. Meanwhile, loss of SPLs may inhibit the expression of APOE4 and confer protection against AD, while the loss of APOE4 expression also disrupts SPLs homeostasis. Moreover, the heightened activation of sphingomyelinase promotes the ferroptosis signaling pathway, leading to exacerbated AD symptoms. Ferroptosis plays a vital role in the pathological progression of AD by influencing Aβ, tau, APOE, and α-Syn. Conversely, the development of AD also exacerbates the manifestation of ferroptosis and SPLs. We are compiling the emerging techniques (Derivatization and IM-MS) of sphingolipidomics, to overcome the challenges of AD diagnosis and treatment. In this review, we examined the intricate neuro-mechanistic interactions between SPLs and Aβ, tau, α-Syn, APOE, and ferroptosis, mediating the onset of AD. Furthermore, our findings highlight the potential of targeting SPLs as underexplored avenue for devising innovative therapeutic strategies against AD. [Display omitted] • The emerging technologies field of sphingolipidomic significantly improved the detectability to achieve more SPL biomarkers. • SPLs can affect AD development by regulating different pathogenesis (Aβ, tau, APOE, and α-Syn) of AD. • Ferroptosis may be a crucial potential pathway by which SPLs regulate AD. • Changes in SPLs might activate ferroptosis pathway consequently the pathogenesis of Aβ, tau, APOE, and α-Syn aggravated AD. [ABSTRACT FROM AUTHOR]

Dissolved organic matter (DOM) plays important roles in the aquatic biogeochemical cycle and the global carbon cycle. However, it is highly spatially and temporally varied due to complex sources from the catchment (allochthonous) and from within the system (autochthonous). Satellite remote sensing provides the ability to monitor DOM and identify the spatio-temporal variations in lakes on a global or regional scale. In this study, field work was conducted in 55 lakes in August 2012 along the middle and lower reaches of the Yangtze River (MLR-YR), where most lakes were characterized by eutrophication due to intense human activities. The results showed that both colored DOM (CDOM) and total DOM differed significantly by and were linearly related to the human-induced trophic state index (TSI), with R 2 = 0.41 and 0.61, respectively. Autochthonous substances by phytoplankton contributed to 38.5% of CDOM and 35.2% of DOM, and allochthonous terrestrial substance indexed by land cover change and aquaculture contributed to almost half, with 49.7% of CDOM and 49.8% of DOM. In total, human activities explained as much as 81.7% and 87.5% of the variations in CDOM and DOM, respectively. Finally, a flowchart for estimating DOM from satellite-derived TSI was proposed. This study has great significance for synchronously monitoring and managing aquatic environment quality in regional eutrophic lakes around the world. Image 1 • Quantity and composition of DOM were greatly varied in lakes along the Yangtze River. • Human activities explained 81.7% and 87.5% variations in CDOM and DOM, respectively. • Trophic state index could serve as a bridge for remotely monitoring DOM from Chl-a. [ABSTRACT FROM AUTHOR]

Abstract Coccolithophorids are key player in the marine biological pump and marine carbon cycle, as their production and community-structure are crucial for export and sequestration of carbon from the atmosphere to the deep sea with important implications to climatic trends. Variations in the species composition of coccolithophore communities largely reflect environmental changes and are therefore fundamental for palaeoceanographic reconstructions. The South China Sea (SCS) is an ideal area to study the response of coccolithophores to environmental change because of the remarkable seasonal and interannual variations of the monsoonal climate and the hydrography. However, to date only limited studies on the temporal changes of coccolithophores in the modern SCS have been reported. In the present work, coccolithophores in the northern SCS were investigated using time-series sediment traps during 2009–2010 and 2011–2012. Extinct coccoliths which had their last occurrence in the Miocene (e.g. Triquetrorhabdulus longus , Reticulofenestra floridanus), Pliocene (e.g. Reticulofenestra pseudoumbilica , Discoaster tamilis), and Pleistocene (e.g. Pseudoemiliania locunosa , Discoaster variabilis) were a frequent component of the coccoliths throughout all the seasons and provided, for the first time, a strong micropaleontological evidence for lateral advective transport in the deep SCS. The source of the fossil coccoliths most likely were the reworked Pleistocene sands which cover the outer shelf and upper slope to the west and south of the Dongsha Islands between 20 m and 600 m water depth. These sediments contain limestone fragments with foraminiferal assemblages of Miocene to Pliocene age, and, to the north and south of the islands, Miocene strata are exposed on the sea floor. Mesoscale eddies, both cyclonic and anticyclonic, were probably the main agent for resuspending and transporting the coccoliths as they propagated westwards along-slope from the Dongsha area to the mooring site. Extant coccolithophore were composed of 31 taxa with Florisphaera profunda , Gephyrocapsa oceanica, and Emiliania huxleyi contributing 91.4% and 83.8% of the annual coccolithophore export flux in 2009–2010 and 2011–2012, respectively; F. profunda was the predominant species. Enhanced fluxes of extant coccoliths occurred in the summer of 2009/2010, spring 2010, autumn 2011 and winter 2011/2012, but varied in phase with the extinct species. Therefore, lateral advection of extant taxa may have also taken place but the extent to which this may have masked primary signals from in-situ coccolithophore production remains open. The low fluxes of coccoliths in the winter of 2009/2010 in association with relatively reduced wind strength, higher SST and a shallower mixed layer might compared to those of 2011/2012 have been driven by the weak El Niño event, which affected the northern SCS during that season. Highlights • Coccolithophores were examined in setting particles in the northern South China Sea. • Extinct coccoliths are a strong micropaleontological evidence for lateral advection. • Source of extinct forms are Pleistocene sands and Miocene outcrops at northern slope. • Mesoscale eddies are the main agent in resuspension and transport of coccoliths. • Lateral advection of extant coccoliths may mask signals from in-situ production. [ABSTRACT FROM AUTHOR]

• Riverine COD content showed high values in the cropland-dominated areas. • Three seasonal variation types were identified for station-based riverine COD. • Variations in riverine COD were co-determined by human and natural factors. Rivers connect terrestrial and aquatic ecosystems and export approximately 55.47 % of the net terrestrial carbon fixation. However, due to unavailable high-frequency monitoring data, litter is known about diurnal variation in riverine carbon transport on a national scale. Based on daily measurements between March 2021 and February 2022 at 1491 stations across China, this study clarified the spatiotemporal variations in riverine organic matter indicated by chemical oxygen demand (COD). Spatially, COD content showed a spatial pattern with high values in the northwest (p < 0.05), and COD flux was determined by water discharge (84.01 %). Human activities explained 73.20 % of the spatial variations in riverine COD content; in particular, agricultural planting significantly elevated riverine COD (r = 0.73, p < 0.01). Seasonally, 95.53 % of stations showed significant seasonal variations in COD contents (p < 0.05); 69.72 % (25.81 %) were identified as Type II (III) typically had the maximum (minimum) COD in summer (autumn). Moreover, except for human activities (41.08 ± 22.94 %), natural factors also contributed 47.41 ± 24.04 % to the seasonal variations. In summer, high temperatures increased COD by promoting algal proliferation at Type II stations; however, heavy precipitation diluted COD contents at Type III stations. In these cases, seasonal measurements were essential for estimating riverine organic matter transport, especially the values measured in spring and winter. This study has significant implications for managing the aquatic environment, estimating riverine organic matter transport, and balancing the global carbon budget. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel algorithm was proposed to remotely observe POC storage in eutrophic lakes. • POC profile could be identified and parameterized by surface Chl-a, POC, and wind. • Spatiotemporal variations in POC storage were determined by temperature and depth. Particulate organic carbon (POC) storage play an essential role in determining carbon sinks and water quality in shallow eutrophic lakes. Although satellite data have been adopted to observe surface POC content, the previous remote sensing results cannot indicate water column-integrated POC storage in shallow eutrophic lakes with vertically nonuniform POC profiles. Based on 272 in-situ POC profiles collected from 19 shallow eutrophic lakes in China's Yangtze-Huai Plain (YHP), this study developed a novel process-oriented method to derive water column-integrated POC storage from OLCI/Sentinel-3A satellite data. The method included three critical steps: remotely estimating surface POC contents, identifying POC profile types (uniform, exponential decay, or power decay) through a binary decision tree, and parameterizing POC profiles using surface POC concentrations. The developed algorithms showed a bias of -25.79% for in-situ match-ups from 15 lakes (N = 88). The POC in the eutrophic lakes was mainly produced by phytoplankton (R 2 = 0.87). As a result, the surface POC content presented a unimodal peak in summer. However, in addition to air temperature regulations (0.52 – 68.53%), the water level also showed apparent effects on increasing POC storage, with relative contributions of 29.29 – 95.51% for the six largest lakes. Therefore, multisource satellite data are needed to derive POC storage in global eutrophic lakes remotely. This study is the first attempt to three-dimensionally observe lake POC contents from space and is important for understanding the carbon cycle in shallow eutrophic lakes. [Display omitted] [ABSTRACT FROM AUTHOR]

• OC transport variations in 41 rivers across China during 2004-2018 were studied. • Human activities were the main driving forces decreasing the riverine OC content. • Chinese rivers are losing their Asian features of low DOC/POC ratios. Rivers serve as regulators of global climate by releasing greenhouse gases, burying particulate carbon, and connecting different ecosystem carbon pools. However, long-term organic carbon (OC) transport features across different Asian rivers are not well known due to unavailable data. Based on routinely monitored environmental and hydrological data during 2004-2018, this study investigated the spatiotemporal variations in dissolved (DOC) and particulate OC (POC) transport across 41 rivers in China. Across different rivers, both DOC (1.35 – 16.8 mg/L) and POC (0.27 – 4.48 mg/L) concentrations covered wide ranges. The DOC content was high in the north and low in the south, with significantly higher (t test, p < 0.01) values for rivers north of 30°N (5.39 ± 3.66 mg/L vs. 2.39 ± 1.14 mg/L). Human activities greatly influenced the riverine DOC and POC distributions. The riverine ammonia nitrogen (NH+ 4-N) content was positively correlated with DOC (r = 0.81 and p < 0.01) and explained 85.59% of its spatial variation. High vegetation coverage had significant effects on decreasing the riverine POC content, with r = -0.55 and p < 0.05. During 2004-2018, water pollution prevention and control strategies decreased DOC concentrations in 60.98% of rivers; meanwhile, anthropogenic vegetation restoration and dam construction led to POC content decreases in 90.48% of rivers. Importantly, along with DOC and POC changes, increasing DOC/POC ratios were found in 90.48% of the rivers, with 42.86% being significant, which indicated that Chinese rivers are losing their Asian features of low DOC/POC ratios due to artificial disturbance. This study is significant for accurately quantifying greenhouse gas emissions, carbon burial, and OC export to estuaries by Chinese rivers. [Display omitted] [ABSTRACT FROM AUTHOR]