Microbial communities from Arctic marine sediments respond slowly to methane addition during ex situ enrichments.

Anaerobic methanotrophic archaea (ANME) consume methane in marine sediments, limiting its release to the water column, but their responses to changes in methane and sulfate supplies remain poorly constrained. To address how methane exposure may affect microbial communities and methane- and sulfur-cycling gene abundances in Arctic marine sediments, we collected sediments from offshore Svalbard that represent geochemical horizons where anaerobic methanotrophy is expected to be active, previously active, and long-inactive based on reaction-transport biogeochemical modelling of porewater sulfate profiles. Sediment slurries were incubated at in situ temperature and pressure with different added methane concentrations. Sediments from an active area of seepage began to reduce sulfate in a methane-dependent manner within months, preceding increased relative abundances of anaerobic methanotrophs ANME-1 within communities. In previously active and long-inactive sediments, sulfur-cycling Deltaproteobacteria became more dominant after 30 days, though these communities showed no evidence of methanotrophy after nearly 8 months of enrichment. Overall, enrichment conditions, but not methane, broadly altered microbial community structure across different enrichment times and sediment types. These results suggest that active ANME populations may require years to develop, and consequently microbial community composition may affect methanotrophic responses to potential large-scale seafloor methane releases in ways that provide insight for future modelling studies.

Diagnosis of severe scrub typhus infection by next-generation sequencing:a case report.

BACKGROUND: Scrub typhus is an acute febrile illness, which was caused by Orientia tsutsugamushi and transmitted through the bite of chiggers. The diagnosis of scrub typhus could be missed diagnosis due to the absence of the pathognomonic eschar. CASE PRESENTATION: A 76-year-old man was hospitalized with fever and kidney injury and was diagnosed of hemorrhagic fever with renal syndrome first. However, the situation of the illness deteriorated into refractory septic shock and multiple organ dysfunction rapidly,although the treatment of anti-sepsis was used in 3rd-5th day. Orientia tsutsugamushi was determined to be the causative pathogen by Next-generation sequencing of his plasma sample in 6th day. Then, the patient was treated with doxycycline and azithromycin and recovered quickly. CONCLUSIONS: Next-generation sequencing was a new diagnostic technology and could identify scrub typhus in accurately and fast without the pathognomonic eschar.

Performance Evaluation of a Newly Developed Chemiluminescent Assay Kit for Detection of Neuron-Specific Eno.

BACKGROUND: To evaluate the performance of a chemiluminescence detection reagent for Neuron-specific enolase (NSE). METHODS: Based on the "Guiding principles on performance analysis of diagnostic, reagents in vitro" and the Clinical and Laboratory Standards Institute (CLSI) Guidelines, performance of the CLIA NSE kit was evaluated, including the detection limit, linear range, reportable range, accuracy, precision, cross reactivity, interference factors, Hook effect, and method comparison. RESULTS: The detection limit of the reagent was 0.05 ng/mL. The linear range of the reagent was 0.05 ng/mL - 400 ng/mL. The reagent can be reported as 0.05 ng/mL - 2,500 ng/mL. The recovery rate ranged from 94.95% to 105.12%. The CV of the reagent of the intra-assay was 3.8% - 5.7% and inter-batch was 3.6%, which meets the requirements. The common interference factors such as the blood fat, jaundice, and rheumatoid factor did not affect the quantitative accuracy of the reagent, but hemolysis resulted in higher readings. Cross-reactions were not observed when incubating with major interfering tumor markers; therefore, the kit was highly specific for NSE. The HOOK effect was not observed when the NSE content reached 20,000 ng/mL in samples. The coincidence rate of the reagent and Roche's products reached 94.81% and the correlation r reached 0.968. CONCLUSIONS: The performance of the NSE CLIA reagent was acceptable in all evaluated parameters, meeting requirements for clinical application.

Evolution of Membrane Fouling Revealed by Label-Free Vibrational Spectroscopic Imaging.

Membrane fouling is the bottleneck that restricts the sustainability of membrane technology for environmental applications. Therefore, the development of novel analytical tools for characterizing membrane fouling processes is essential. In this work, we demonstrate a capability of probing the chemical structure of foulants and detecting their 3-dimentional spatial distribution on membranes based on stimulated Raman scattering (SRS) microscopy as a vibrational spectroscopic imaging approach. The adsorption process of foulants onto membrane surfaces and their aggregation process within membrane pores during the microfiltration of protein and polysaccharide solutions were clearly monitored. Pore constriction and cake layer formation were found to be the coupled membrane fouling mechanisms. This work establishes an ultrafast, highly sensitive, nondestructive and label-free imaging platform for the characterization of membrane fouling evolution. Furthermore, this work provides new insights into membrane fouling and offers a powerful tool for membrane-based process exploration.

Antibiotic resistance at environmental multi-media interfaces through integrated genotype and phenotype analysis.

Antibiotic resistance is currently an unfolding global crisis threatening human health worldwide. While antibiotic resistance genes (ARGs) are known to be pervasive in environmental media, the occurrence of antibiotic resistance at interfaces between two or more adjacent media is largely unknown. Here, we designed a microcosm study to simulate plastic pollution in paddy soil and used a novel method, stimulated Raman scattering coupled with deuterium oxide (D2O) labelling, to compare the antibiotic resistance in a single medium with that at the interface of multiple environmental media (plastic, soil, water). Results revealed that the involvement of more types of environmental media at interfaces led to a higher proportion of active resistant bacteria. Genotypic analysis showed that ARGs (especially high-risk ARGs) and mobile genetic elements (MGEs) were all highly enriched at the interfaces. This enrichment was further enhanced by the co-stress of heavy metal (arsenic) and antibiotic (ciprofloxacin). Our study is the first to apply stimulated Raman scattering to elucidate antibiotic resistance at environmental interfaces and reveals novel pathway of antibiotic resistance dissemination in the environment and overlooked risks to human health.

The phylogeography and ecology of Oligobrachia frenulate species suggest a generalist chemosynthesis-based fauna in the arctic.

We used ancient DNA (aDNA) extraction methods to sequence museum voucher samples of Oligobrachia webbi, a frenulate siboglinid polychaete described from a northern Norwegian fjord over fifty years ago. Our sequencing results indicate a genetic match with the cryptic seep species, Oligobrachia haakonmosbiensis (99% pairwise identity for 574 bp mtCOI fragments). Due to its similarity with O. webbi, the identity of O. haakonmosbiensis has been a matter of debate since its description, which we have now resolved. Furthermore, our results demonstrate that chemosynthesis-based siboglinids, that constitute the bulk of the biomass at Arctic seeps are not seep specialists. Our data on sediment geochemistry and carbon and nitrogen content reveal reduced conditions in fjords/sounds, similar to those at seep systems. Accumulation and decomposition of both terrestrial and marine organic matter results in the buildup of methane and sulfide that apparently can sustain chemosymbiotic fauna. The occurrence of fjords and by extension, highly reducing habitats, could have led to Arctic chemosymbiotic species being relatively generalist with their habitat, as opposed to being seep or vent specialists. Our stable isotope analyses indicate the incorporation of photosynthetically derived carbon in some individuals, which aligns with experiments conducted on frenulates before the discovery of chemosynthesis that demonstrated their ability to take up organic molecules from the surrounding sediment. Since reduced gases in non-seep environments are ultimately sourced from photosynthetic processes, we suggest that the extreme seasonality of the Arctic has resulted in Arctic chemosymbiotic animals seasonally changing their degree of reliance on chemosynthetic partners. Overall, the role of chemosynthesis in Arctic benthos and marine ecosystems and links to photosynthesis may be complex, and more extensive than currently known.

Assessing the impact of freshwater discharge on the fluid chemistry in the Svalbard fjords.

Changes in the cryosphere extent (e.g., glacier, ice sheet, permafrost, and snow) have been speculated to impact (bio)geochemical interactions and element budgets of seawater and pore fluids in Arctic regions. However, this process has rarely been documented in Arctic fjords, which leads to a poor systematic understanding of land-ocean interactions in such a warming-susceptible region. Here, we present the chemical and isotopic (δ18O, δD, δ11B, and 87Sr/86Sr) compositions of seawater and pore fluids from five fjords in the Svalbard archipelago. Compared to bottom seawater, the low Cl- concentrations and depleted water isotopic signatures (δ18O and δD) of surface seawater and pore fluids delineate freshwater discharge originating from precipitation and/or meltwater of the cryosphere (i.e., glacier, snow, and permafrost). In contrast, the high Cl- concentrations with light water isotopic values in pore fluids from Dicksonfjorden indicate a brine probably resulted from submarine permafrost formation during the late Holocene, a timing supported by the numerical simulation of dissolved Cl- concentration. The freshwater is influenced by the local diagenetic processes such as ion exchanges indicated by δ11B signatures as well as interactions with bedrock during fluid migration inferred from pore fluid 87Sr/86Sr ratios. The interactions with bedrock significantly alter the hydrogeochemical properties of pore fluids in each fjord, yielding spatiotemporal variations. Consequently, land-ocean interactions in combination with the hydrosphere-cryosphere-lithosphere are critical factors for understanding and predicting the hydrology and elemental cycling during global climate change periods in the past, present, and future of the Svalbard archipelago.

[Stratified analysis of the relationship between traditional Chinese medicine constitutional types and health status in the general population based on data of 8,448 cases].

OBJECTIVE: To examine the relationship between traditional Chinese medicine (TCM) constitutional types and health status among groups of different age or gender in the general population of China. METHODS: Data of 8 448 cases were randomly sampled from a database of 21 948 cases of a cross-sectional survey on the TCM constitutional types and health status which was carried out in 9 provinces or municipalities of China (Jiangsu, Anhui, Gansu, Qinghai, Fujian, Beijing, Jilin, Jiangxi and Henan) according to gender and age structure of the Chinese population in 2005. Scores of health-related quality of life scale--the Medical Outcomes Study 36-Item Short-Form Health Survey (MOS SF-36)--were analyzed by Nemenyi test to compare the health status of individuals with different constitutional types. RESULTS: Compared with the gentleness type, the MOS SF-36 scores of the 8 types of pathological constitution were significantly low (P<0.05) among groups of different age or gender. The MOS SF-36 score was the lowest in men of the qi-deficiency, qi-depression and blood-stasis types, while it was the lowest in women of the phlegm-dampness, qi-depression and qi-deficiency types. For the age group of 15 to 34, the special diathesis, qi-depression and blood-stasis types had the lowest MOS SF-36 scores; for the age group of 35 to 59, the qi-deficiency, qi-depression and blood-stasis types had the lowest MOS SF-36 scores; for the age group of over 60, the qi-deficiency, qi-depression and phlegm-dampness types had the lowest MOS SF-36 scores. CONCLUSION: In groups of different gender or age, the MOS SF-36 scores of the 8 types of pathological constitution were significantly lower than that of the gentleness type, indicating a deficient health status. The health status of different types of constitution showed different characteristics in groups of different gender or age.

Distinct methane-dependent biogeochemical states in Arctic seafloor gas hydrate mounds.

Archaea mediating anaerobic methane oxidation are key in preventing methane produced in marine sediments from reaching the hydrosphere; however, a complete understanding of how microbial communities in natural settings respond to changes in the flux of methane remains largely uncharacterized. We investigate microbial communities in gas hydrate-bearing seafloor mounds at Storfjordrenna, offshore Svalbard in the high Arctic, where we identify distinct methane concentration profiles that include steady-state, recently-increasing subsurface diffusive flux, and active gas seepage. Populations of anaerobic methanotrophs and sulfate-reducing bacteria were highest at the seep site, while decreased community diversity was associated with a recent increase in methane influx. Despite high methane fluxes and methanotroph doubling times estimated at 5-9 months, microbial community responses were largely synchronous with the advancement of methane into shallower sediment horizons. Together, these provide a framework for interpreting subseafloor microbial responses to methane escape in a warming Arctic Ocean.

Lead-free cesium tin halide nanocrystals for light-emitting diodes and color down conversion.

Organometal halide perovskites are attracting a great deal of attention because of their long carrier diffusion lengths, wide wavelength tunability, and narrow-band emission. However, the toxicity of lead has caused considerable environmental and health concerns. In this work, lead-free cesium tin halide nanocrystals are synthesized and investigated. CsSnBr3 and CsSnI3 nanocrystals, 25 and 7 nm in size, are synthesized by a facile hot injection method. Absorption spectroscopy, photoluminescence spectroscopy, and X-ray diffraction were used to understand their structural and optical properties. CsSnBr3 and CsSnI3 nanocrystals show emission peaks at 683 and 938 nm, respectively. These nanocrystals show shelf stability for a few months. Temperature-dependent photoluminescence is utilized to know more about fundamental physical parameters, such as exciton binding energy, charge carrier-phonon interactions and band gap. Light-emitting diodes and color down-conversion films are also demonstrated using these lead free perovskite nanocrystals.

Discharge of deeply rooted fluids from submarine mud volcanism in the Taiwan accretionary prism.

Qualitative and quantitative assessments of fluid cycling are essential to address the role and transport of deeply sourced fluids in subduction systems. In this study, sediment cores distributed across a submarine mud volcano (SMV) offshore southwestern Taiwan were investigated to determine the characteristics of fluids generated through the convergence between the Eurasian and Phillippine Sea Plates. The low dissolved chloride concentration combined with the enrichment of 18O, and depletion of 2H of pore fluids suggest the discharge of deep freshwater formed by smectite dehydration at an equilibrium temperature of 100 to 150 °C. The upward fluid velocities, decreasing from 2.0 to 5.0 cm yr-1 at the center to a negligible value at margin sites, varied with the rate and efficiency of anaerobic methanotrophy, demonstrating the impact of fluid migration on biogeochemical processes and carbon cycling. By extrapolating the velocity pattern, the flux of fluids exported from 13 SMVs into seawater amounted up to 1.3-2.5 × 107 kg yr-1, a quantity accounting for 1.1-28.6% of the smectite-bound water originally stored in the incoming sediments. Our results imply that SMVs could act as a conduit to channel the fluids produced from great depth/temperature into seafloor environments in a subduction system of the western Pacific Ocean.

Atypical biological features of a new cold seep site on the Lofoten-Vesterålen continental margin (northern Norway).

A newly discovered cold seep from the Lofoten-Vesterålen margin (Norwegian Sea) is dominated by the chemosymbiotrophic siboglinid Oligobrachia haakonmosbiensis like other high latitude seeps, but additionally displays uncharacteristic features. Sulphidic bottom water likely prevents colonization by cnidarians and sponges, resulting in fewer taxa than deeper seeps in the region, representing a deviation from depth-related trends seen among seeps elsewhere. O. haakonmosbiensis was present among carbonate and barite crusts, constituting the first record of frenulates among hard substrates. The presence of both adults and egg cases indicate that Ambylraja hyperborea skates use the site as an egg case nursery ground. Due to sub-zero ambient temperatures (-0.7 °C), we hypothesize that small, seepage related heat anomalies aid egg incubation and prevent embryo mortality. We place our results within the context of high-latitude seeps and suggest they exert evolutionary pressure on benthic species, thereby selecting for elevated exploitation and occupancy of high-productivity habitats.

Image based quantitative comparisons indicate heightened megabenthos diversity and abundance at a site of weak hydrocarbon seepage in the southwestern Barents Sea.

BACKGROUND: High primary productivity in the midst of high toxicity defines hydrocarbon seeps; this feature usually results in significantly higher biomass, but in lower diversity communities at seeps rather than in the surrounding non-seep benthos. Qualitative estimates indicate that this dichotomy does not necessarily hold true in high latitude regions with respect to megafauna. Instead, high latitude seeps appear to function as local hotspots of both megafaunal diversity and abundance, although quantitative studies do not exist. In this study, we tested this hypothesis quantitatively by comparing georeferenced seafloor mosaics of a seep in the southwestern Barents Sea with the adjacent non-seep seafloor. METHODS: Seafloor images of the Svanefjell seep site and the adjacent non seep-influenced background seabed in the southwestern Barents Sea were used to construct georeferenced mosaics. All megafauna were enumerated and mapped on these mosaics and comparisons of the communities at the seep site and the non-seep background site were compared. Sediment push cores were taken in order to assess the sediment geochemical environment. RESULTS: Taxonomic richness and abundance were both considerably higher at the seep site than the non-seep location. However, taxa were fewer at the seep site compared to other seeps in the Barents Sea or the Arctic, which is likely due to the Svanefjell seep site exhibiting relatively low seepage rates (and correspondingly less chemosynthesis based primary production). Crusts of seep carbonates account for the higher diversity of the seep site compared to the background site, since most animals were either colonizing crust surfaces or using them for shelter or coverage. Our results indicate that seeps in northern latitudes can enhance local benthic diversity and this effect can take place even with weak seepage. Since crusts of seep carbonates account for most of the aggregating effect of sites experiencing moderate/weak seepage such as the study site, this means that the ability of seep sites to attract benthic species extends well beyond the life cycle of the seep itself, which has important implications for the larger marine ecosystem and its management policies.

Ultrastable, Deformable, and Stretchable Luminescent Organic-Inorganic Perovskite Nanocrystal-Polymer Composites for 3D Printing and White Light-Emitting Diodes.

Organic-inorganic perovskite nanocrystals with excellent optoelectronic properties have been utilized in various applications, despite their stability issues. The perovskite materials are sensitive to environments such as polar solvents, moisture, and heat. Thus, they are not used for extrusion three-dimensional (3D) printing, as it is usually conducted in the ambient environment and requires heating to liquefy the printed materials. In this work, 11 thermoplastic polymers conventionally used for extrusion 3D printing were investigated to test their capability as protective encapsulation materials for perovskite nanocrystals. Three of them exhibited good protective properties, and one (polycaprolactone, PCL) of these three could be blended with perovskite nanocrystals to form perovskite nanocrystal-PCL composites, which were deformable and stretchable once heated. Because of the low melting point of PCL, the perovskite nanocrystals maintained their optical properties after 3D printing, and the printed objects were still having fluorescent behavior. Moreover, fluorescent micrometer-sized fibers based on the perovskite nanocrystal-PCL composites could also be simply prepared using cotton candy makers. Perovskite nanocrystal-PCL composite films with different emission wavelengths were incorporated with blue light-emitting diodes (LEDs) to realize white LEDs with Commission Internationale de l'Éclairage chromaticity coordinates of (0.33, 0.33).

Conservative treatment of supination and external rotation for type Ⅲ and Ⅳankle fracture by bone setting / 中国骨伤

OBJECTIVE@#To explore curative effect of conservative treatment of supination-lateral rotation (SER) with type Ⅲ and Ⅳ ankle fracture by bone setting technique.@*METHODS@#From January 2017 to December 2019, 64 patients diagnosed with SER with type Ⅲ and Ⅳ ankle fracture were treated with manipulative reduction and conservative treatment (manipulation group) and surgical treatment with open reduction and internal fixation (operation group), 32 patients in each group. In manipulation group, there were 17 males and 15 females, aged from 15 to 79 years old with an average of (51.42±13.68) years old;according to Lauge-Hansen classification, there were 8 patients with supination external rotation type Ⅲ and 24 patients with type Ⅳ. In operation group, there were 13 males and 19 females, aged from 18 to 76 years old with an average of (47.36±15.02) years old;7 patients with type Ⅲ and 25 patients with type Ⅳ. Displacement of ankle fracture was measured by Digimizer software, and compared before treatment, 3 and 12 months after treatment between two groups. Lateral medial malleolus displacement, lateral medial malleolus displacement, lateral malleolus displacement, lateral malleolus displacement, lateral malleolus contraction displacement and posterior malleolus displacement were measured and compared between two groups. Mazur score was used to evaluate ankle joint function.@*RESULTS@#All patients were followed up from 12 to 36 months with an average of (17.16±9.36) months. There were statistical differences in lateral medial malleolus displacement, lateral medial malleolus displacement, lateral malleolus displacement, lateral malleolus displacement, lateral malleolus contraction displacement and posterior malleolus displacement in manipulation group before and after reduction(P<0.05). Compared with operation group, there were no statistically significant differences in lateral malleolus shift, lateral malleolus shift, lateral malleolus contraction shift(P>0.05), while there were statistically significant differences in lateral malleolus shift, posterior malleolus shift up and down (P<0.05). Mazur scores of ankle joint at 3 months after treatment in manipulation group and operation group were 68.84±13.08 and 82.53±7.31, respectively, and had statistical differences(P<0.05), while there was no difference in evaluation of clnical effect(P>0.05). There were no differences in Mazur score and evaluation of clnical effect between two groups at 12 months after treatment (P>0.05).@*CONCLUSION@#Bone setting technique could effectively correct lateral displacement of medial malleolus, lateral displacement of medial malleolus, lateral displacement of lateral malleolus and lateral contraction displacement of lateral malleolus in supination lateral rotation type Ⅲ and Ⅳ ankle fracture, and has good long-term clinical effect, which could avoid operation for some patients and restore ankle function after fracture.

Anti-depressant components and mechanism of Rehmanniae Radix based on UPLC-Q-Orbitrap HRMS and network pharmacology / 中国中药杂志

This study aimed to explore the anti-depressant components of Rehmanniae Radix and its action mechanism based on network pharmacology combined with molecular docking. The main components of Rehmanniae Radix were identified by ultra-high performance liquid chromatography-quadrupole/Orbitrap high resolution mass spectrometry(UPLC-Q-Orbitrap HRMS), and the related targets were predicted using SwissTargetPrediction. Following the collection of depression-related targets from GeneCards, OMIM and TTD, a protein-protein interaction(PPI) network was constructed using STRING. GO and KEGG pathway enrichment analysis was performed by Metascape. Cytoscape 3.7.2 was used to construct the networks of "components-targets-disease" and "components-targets-pathways", based on which the key targets and their corresponding components were obtained and then preliminarily verified by molecular docking. Rehmanniae Radix contained 85 components including iridoids, ionones, and phenylethanoid glycosides. The results of network analysis showed that the main anti-depressant components of Rehmanniae Radix were catalpol, melittoside, genameside C, gardoside, 6-O-p-coumaroyl ajugol, genipin-1-gentiobioside, jiocarotenoside A1, neo-rehmannioside, rehmannioside C, jionoside C, jionoside D, verbascoside, rehmannioside, cistanoside F, and leucosceptoside A, corresponding to the following 16 core anti-depression targets: AKT1, ALB, IL6, APP, MAPK1, CXCL8, VEGFA, TNF, HSP90 AA1, SIRT1, CNR1, CTNNB1, OPRM1, DRD2, ESR1, and SLC6 A4. As revealed by molecular docking, hydrogen bonding and hydrophobicity might be the main action forms. The key anti-depression targets of Rehmanniae Radix were concentrated in 24 signaling pathways, including neuroactive ligand-receptor interaction, neurodegenerative disease-multiple diseases pathway, phosphatidylinositol 3-kinase/protein kinase B pathway, serotonergic synapse, and Alzheimer's disease.

Seepage from an arctic shallow marine gas hydrate reservoir is insensitive to momentary ocean warming.

Arctic gas hydrate reservoirs located in shallow water and proximal to the sediment-water interface are thought to be sensitive to bottom water warming that may trigger gas hydrate dissociation and the release of methane. Here, we evaluate bottom water temperature as a potential driver for hydrate dissociation and methane release from a recently discovered, gas-hydrate-bearing system south of Spitsbergen (Storfjordrenna, ∼380 m water depth). Modelling of the non-steady-state porewater profiles and observations of distinct layers of methane-derived authigenic carbonate nodules in the sediments indicate centurial to millennial methane emissions in the region. Results of temperature modelling suggest limited impact of short-term warming on gas hydrates deeper than a few metres in the sediments. We conclude that the ongoing and past methane emission episodes at the investigated sites are likely due to the episodic ventilation of deep reservoirs rather than warming-induced gas hydrate dissociation in this shallow water seep site.

Erratum: Seepage from an arctic shallow marine gas hydrate reservoir is insensitive to momentary ocean warming.

This corrects the article DOI: 10.1038/ncomms15745.

Efficient Low-Temperature Solution-Processed Lead-Free Perovskite Infrared Light-Emitting Diodes.

Lead-free perovskite infrared light-emitting diodes are achieved by using a halide perovskite CsSnI3 as an emissive layer. The film shows compact micrometer-sized grains with only a few pinholes and cracks at the grain boundaries. The device exhibits maximum radiance of 40 W sr-1 m-2 at a current density of 364.3 mA cm-2 and maximum external quantum efficiency of 3.8% at 4.5 V.

Production of fluorescent dissolved organic matter in Arctic Ocean sediments.

Little is known about the production of fluorescent dissolved organic matter (FDOM) in the anoxic oceanic sediments. In this study, sediment pore waters were sampled from four different sites in the Chukchi-East Siberian Seas area to examine the bulk dissolved organic carbon (DOC) and their optical properties. The production of FDOM, coupled with the increase of nutrients, was observed above the sulfate-methane-transition-zone (SMTZ). The presence of FDOM was concurrent with sulfate reduction and increased alkalinity (R2 > 0.96, p < 0.0001), suggesting a link to organic matter degradation. This inference was supported by the positive correlation (R2 > 0.95, p < 0.0001) between the net production of FDOM and the modeled degradation rates of particulate organic carbon sulfate reduction. The production of FDOM was more pronounced in a shallow shelf site S1 with a total net production ranging from 17.9 to 62.3 RU for different FDOM components above the SMTZ depth of ca. 4.1 mbsf, which presumably underwent more accumulation of particulate organic matter than the other three deeper sites. The sediments were generally found to be the sources of CDOM and FDOM to the overlying water column, unearthing a channel of generally bio-refractory and pre-aged DOM to the oceans.