High-Throughput Screening Strategy for Electrocatalysts for Selective Catalytic Oxidation of Formaldehyde to Formic Acid.

Electrocatalytic oxidation of formaldehyde (FOR) is an effective way to prevent the damage caused by formaldehyde and produce high-value products. A screening strategy of a single-layer MnO2-supported transition metal catalyst for the selective oxidation of formaldehyde to formic acid was designed by high-throughput density functional calculation. N-MnO2@Cu and MnO2@Cu are predicted to be potential FOR electrocatalysts with potential-limiting steps (PDS) of 0.008 and -0.009 eV, respectively. Electronic structure analysis of single-atom catalysts (SACs) shows that single-layer MnO2 can regulate the spin density of loaded transition metal and thus regulate the adsorption of HCHO (Ead), and Ead is volcanically distributed with the magnetic moment descriptor -|mM - mH|. In addition, the formula quantifies Ead and |mM - mH| to construct a volcano-type descriptor α describing the PDS [ΔG(*CHO)]. Other electronic and structural properties of SACs and α are used as input features for the GBR method to construct machine learning models predicting the PDS (R2 = 0.97). This study hopes to provide some insights into FOR electrocatalysts.

Advances on micro/nanoplastics and their effects on the living organisms: A review.

Micro/nanoplastics (MPs) are attracting increasing attention owing to the potential threats they pose to the sustainability of the environment and the health of living organisms. Thus, a comprehensive understanding of the influence of MPs on living organisms is vital for developing countermeasures. We conducted an extensive literature search to retrieve the articles related to MPs via the Web of Science. Accordingly, 152 articles published in the last decade and in influential journals were selected to analyze the effects of MPs on plants, animals, microorganisms, and humans as well as the current status, hotspots, and trends of studies on MPs. The results showed that owing to the special characteristics of MPs and anthropogenic activities, MPs have become ubiquitous worldwide. MPs are ingested by plants and animals and enter the human body through various pathways, resulting in numerous adverse effects, such as growth inhibition, oxidative stress, inflammation, organ damage, and germ cell lesions. Moreover, they affect microorganisms by reshaping the structure and function of microbial communities and changing the spread pathway. However, microorganisms can also contribute to the degradation of MPs. With increasing evidence of the adverse effects of MPs on biota, coping with MP pollution and mitigating harmful outcomes have emerged as major challenges. This review focuses on (1) the main effects of MPs on living organisms, ranging from microorganisms to humans, (2) the current status and hotspots of studies related to MPs, and (3) the challenges and prospects of further studies on MPs.

Diagnostic value of circulating microRNAs for esophageal cancer: a meta-analysis based on Asian data.

BACKGROUND AND OBJECTIVE: esophageal cancer (EC) is one of the most common gastrointestinal malignant diseases. We conducted a comprehensive meta-analysis to explore the clinical applicability of circulating microRNA for the diagnosis of EC. METHODS: as of September 10, 2021, a comprehensive literature search was conducted on PubMed, Embase, Web of Science, Cochrane Library, Wanfang Database, and China National Knowledge Infrastructure (CNKI) to identify eligible studies. The sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the curve (AUC) were pooled to evaluate the test performance. The potential sources of heterogeneity were analyzed by subgroup analysis. Deeks' funnel plot was used to assess publication bias. RESULTS: 85 studies from 50 articles were included in the current meta-analysis. The overall pooled sensitivity was 0.82 (95 % CI, 0.79-0.84), specificity was 0.84 (95 % CI, 0.81-0.86), PLR was 4.9 (95 % CI, 4.2-5.9), NLR was 0.22 (95 % CI, 0.19-0.25), DOR was 22 (95 % CI, 17-29) and AUC was 0.89 (95 % CI, 0.86-0.92), respectively. Subgroup analysis suggested that miRNA clusters with a large sample size showed better diagnostic accuracy. Publication bias was not found. CONCLUSIONS: circulating miRNAs can be used as a potential non-invasive biomarker for the diagnosis of EC in Asian populations.

Circulating microRNAs as Potential Biomarkers for the Diagnosis of Endometrial Cancer: a Meta-Analysis.

Endometrial cancer (EC) is the most common female genital tract malignancy worldwide. Many investigators have confirmed the possibility of using circulating miRNAs to diagnose EC; however, the results were inconsistent. Therefore, we performed the current meta-analysis to systematically evaluate the diagnostic value of circulating miRNAs in EC. We carefully searched relevant articles published prior to February 15, 2022 in the databases of PubMed, Embase, Web of Science, Cochrane Library, Wanfang database, and China National Knowledge Infrastructure (CNKI) based on PRISMA statement. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the curve (AUC) were calculated to test the diagnostic accuracy. Furthermore, subgroup analyses were performed to identify the potential sources of heterogeneity, and the Deeks' funnel plot asymmetry test was used to evaluate the potential publication bias. Twenty-one studies from 12 articles including a total of 2305 participants (1341 EC patients and 964 controls) were included in the current diagnostic meta-analysis. The overall pooled results of miRNA for EC diagnosis were: sensitivity, 0.84 (95% CI: 0.79-0.88); specificity, 0.87 (95% CI: 0.79-0.91); PLR, 6.3 (95% CI: 3.9-10.0); NLR, 0.18 (95% CI: 0.13-0.25); DOR, 35 (95% CI: 17-71); and AUC was 0.91 (95% CI: 0.89-0.94). Subgroup analysis suggested that miRNA cluster, serum type, and large sample sizes showed a better diagnostic accuracy. Moreover, there was no significant publication bias. Circulating miRNAs have great potential as novel non-invasive biomarkers for EC diagnosis.

Spin regulation for efficient electrocatalytic N2 reduction over diatomic Fe-Mo catalyst.

Electrocatalytic nitrogen reduction reaction (eNRR) is a promising method for the sustainable production of ammonia as an alternative to the traditional energy-intensive Haber-Bosch process. In this work, an efficient strategy by atomic spin regulation to promote NRR through Fe-transition metal (TM) hybrid heteronuclear dual-atom catalysts has been studied. By means of DFT computations, the stability, activity, and selectivity of 30 kinds of Fe-based dual-atoms anchored on N-doped porous graphene are systematically investigated to evaluate their catalytic performance. Fe/MoNC is screened as an excellent NRR catalyst with the limiting potentials of 0.63 V, and also suppresses HER. In the Fe/MoNC, the neighboring Fe atom regulates the spin state of the Mo center in MoN4 from high-spin state (2.63 µB) to medium-spin state (0.74 µB), which can effectively relieve the strong overlapping between Mo 4d orbital with the NxHy intermediates, promote the desorption of reaction product, and eventually achieve a lower limiting potential. Interestingly, the archetype of the active center of nitrogenase is also a FeMo-cofactor, which is consistent with our screening results. The work may provide new insight into the mechanism of nitrogenase, and promote the rational design of efficient NRR catalysts by atomic spin regulation.

Generic Cutting Force Modeling with Comprehensively Considering Tool Edge Radius, Tool Flank Wear and Tool Runout in Micro-End Milling.

Accurate cutting force prediction is crucial in improving machining precision and surface quality in the micro-milling process, in which tool wear and runout are essential factors. A generic analytic cutting force model considering the effect of tool edge radius on tool flank wear and tool runout in the micro-end milling process is proposed. Based on the analytic modeling of the cutting part of the cutting edge in the end face of the micro-end mill bottom, the actual radius model of the worn tool is established, considering the tool edge radius and tool flank wear. The tool edge radius, tool wear, tool runout, trochoidal trajectories of the current cutting edge, and all cutting edges in the previous cycle are comprehensively considered in the instantaneous uncut chip thickness calculation and the cutter-workpiece engagement determination. The cutting force coefficient model including tool wear is established. A series of milling experiments are performed to verify the accuracy and effectiveness of the proposed cutting force model. The results show that the predicted cutting forces are in good agreement with the experimental cutting forces, and it is necessary to consider tool wear in the micro-milling force modeling. The results indicate that tool wear has a significant influence on the cutting forces and cutting force coefficients in the three directions, and the influences of tool wear on the axial cutting force and axial force coefficient are the largest, respectively. The proposed cutting force model can contribute to real-time machining process monitoring, cutting parameters optimization and ensuring machining quality.

Stimulation of high-concentration dissolved nitrogen and reactive phosphorus in Lake Taihu sediments on the initiation and maintenance of cyanobacterial blooms.

The spatio-temporal variation of dissolved inorganic nitrogen (DIN: NH4+-N, NO2--N, and NO3--N) and dissolved reactive phosphorus (DRP) in Meiliang Bay of Lake Taihu sediments and their potential effects on the cyanobacterial blooms were studied. Monthly sampling was performed using high-resolution dialysis sampling devices (HR-Peeper) and two important results were observed in April (the initiation period of cyanobacterial bloom) and June-August (the maintenance period of cyanobacterial blooms). In April, high concentrations of dissolved NO2--N and NO3--N, probably caused by the groundwater influx, were observed in deep anoxic sediments (below 110 mm). NO2--N and NO3--N are good electron acceptors for the mineralization of organic P under anaerobic conditions and should lead to an increase in DRP concentrations in sediments, DRP released from sediments thus further stimulating the cyanobacterial growth and the outbreak of severe cyanobacterial blooms in May due to the extremely low concentrations of DRP in the water body. From June to August, high concentrations of NO2--N, NO3--N, and DRP were observed in the surface sediment, which was caused by the release of NH4+-N from the mineralization of cyanobacterial debris. This should play an important role in maintaining cyanobacterial growth, especially in stimulating the occurrence of cyanobacterial blooms during September, when N and P were co-limited. This study revealed high-concentration DIN and DRP in Lake Taihu sediments potentially stimulated the initiation and maintenance of cyanobacterial blooms.

The epidemiological status of osteoporotic hip fractures: A bicentric comparative and retrospective study.

BACKGROUND: Osteoporotic hip fractures have posed a significant burden to society, and more epidemiological data is required. OBJECTIVE: To compare the epidemiological differences of hip fracture patients in Spain and China. METHOD: This was a retrospective comparative study. Comparisons were made in terms of morbidity, demographic and anthropometric characteristics, length of stay, cost of hospitalization, and mortality by consulting the medical histories of osteoporotic hip fractures in two hospitals. The t test was used for measurement data, and the X2 test was used for count data. The difference is statistically significant when p< 0.05. RESULTS: A total of 757 patients were enrolled in this study, with 426 from Virgen Macarena University Hospital (HUVM) and 331 from Xi'an Daxing Hospital (XDH). The average age was 81.4 ± 9.26 and 76.0 ± 8.08 years; the proportion of women was 74.9% and 68.0%, respectively. The incidence of osteoporotic hip fractures in Seville residents over 50 years old was approximately 239 per 100,000 residents, compared to 158 per 100,000 residents in Xi'an. The timing of surgery in Spanish patients was significantly longer than in Chinese patients, 78.7 ± 48.2 vs. 60.7 ± 43.1 hours, p= 0.000. There were 81 deaths in Spain and 43 deaths in China during the one-year follow-up period (p= 0.026). CONCLUSIONS: In terms of incidence, demographics, surgical methods, and mortality, there are significant differences between hip fracture patients in Seville, Spain and Xi'an, China.

Adsorption Behavior of Environmental Gas Molecules on Pristine and Defective MoSi2N4: Possible Application as Highly Sensitive and Reusable Gas Sensors.

Inspired by the recent practical application of two-dimensional (2D) nanomaterials as gas sensors, catalysts, and materials for waste gas disposal, herein, the adsorption behaviors of environmental gas molecules, including NO, CO, O2, CO2, NO2, H2O, H2S, and NH3, on the 2D pristine and defective MoSi2N4 (MSN) monolayers were systematically investigated using spin-polarized density functional theory (DFT) calculations. Our results reveal that all the gas molecules are physically adsorbed on the MSN surface with small charge transfer, but the electronic structures of NO, NO2, and O2 are obviously modified due to the in-gap states. The introduction of N vacancy on the MSN surface enhances the interaction between gas molecules and the substrate, especially for NO2 and O2. Interestingly, the adsorption type of NO and CO evolves from physisorption to chemisorption, which may be utilized in NO and CO catalytic reaction. Furthermore, the moderate adsorption strength and obvious changes in electronic properties of H2O and H2S on the defective MSN make them have promising prospects in highly sensitive and reusable gas sensors. This work offers several promising gas sensors based on the MSN monolayer and also provides a theoretical reference of other related 2D materials in the field of gas sensors, catalysts, and toxic gas disposal.

Diagnostic accuracy of circulating microRNA in hepatitis B virus-related hepatocellular carcinoma: a meta-analysis based on Asian data.

BACKGROUND AND AIM: hepatitis B virus (HBV) is the main risk factor for hepatocellular carcinoma (HCC). We performed a meta-analysis based on Asian data to evaluate the diagnostic accuracy of circulating microRNA as a non-invasive biomarker in the diagnosis of HBV-related HCC. METHODS: a comprehensive literature search (updated to May 12, 2021) in PubMed, Embase, Web of Science, Wanfang Database, and China National Knowledge Infrastructure (CNKI) was performed to identify eligible studies. The sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the curve (AUC) for diagnosing HBV-related HCC were pooled in this meta-analysis. A subgroup analysis was performed to explore heterogeneity, and Deeks' funnel plot was used to assess publication bias. RESULTS: a total of 19 articles including 32 studies were included in the current meta-analysis. The overall sensitivity, specificity, PLR, NLR, DOR and AUC were 0.83 (95 % CI: 0.79 to 0.87), 0.78 (95 % CI: 0.73 to 0.83), 3.9 (95 % CI: 3.0 to 4.9), 0.21 (95 % CI: 0.16 to 0.27), 18 (95 % CI: 12 to 27) and 0.88 (95 % CI: 0.85 to 0.91), respectively. Subgroup analysis shows that miRNA clusters with a large sample size showed better diagnostic accuracy. Although there is no publication bias, the research still has some limitations. CONCLUSIONS: circulating miRNAs could serve as a potential non-invasive biomarker in diagnosing HBV-related HCC in Asian populations.

The Potential Diagnostic Accuracy of Let-7 Family for Cancer: A Meta-Analysis.

BACKGROUND: Cancer is a global public health problem affecting human health. Early stage of cancer diagnosis, when it is not too large and has not spread is important for successful treatment. Many researchers have proposed that the let-7 microRNA family can be used as a biomarker for cancer diagnosis. The aim of this meta-analysis is to evaluate whether let-7 family can be used as a diagnostic tool for cancer patients. METHODS: We conducted a comprehensive literature search on PubMed, EMBASE, Web of Science, Cochrane Library, Google Scholar, China National Knowledge Infrastructure (CNKI) and Wanfang database, updated to October 23, 2020. A random effects model was used to pool the sensitivity and specificity. Besides, we measured the diagnostic value using positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and area under the curve (AUC) were pooled. In addition, meta-regression and subgroup analysis were performed to explore the possible sources of heterogeneity, and Deeks' funnel chart was used to assess whether there was publication bias. RESULTS: 31 studies from 15 articles were included in the current meta-analysis. The overall sensitivity, specificity, PLR, NLR, DOR and AUC were 0.80 (95% CI: 0.75-0.85), 0.81 (95% CI: 0.74-0.86), 4.2 (95% CI: 2.9-5.9), 0.24 (95% CI: 0.19-0.32), 17 (95% CI: 10-29) and 0.87 (95% CI: 0.84-0.90), respectively. Subgroup analysis shows that the let-7 family cluster of serum type showed a better diagnostic accuracy of cancer, especially the breast cancer. Although there is no publication bias, it still has some limitations. CONCLUSIONS: let-7 family can be considered as a promising non-invasive diagnostic biomarker for cancer.

Rehabilitation guidance for hip fracture patients during the COVID-19 pandemic using chat software: A new model.

BACKGROUND: Hip fractures are serious fractures for the elderly. The rehabilitation of patients with hip fractures has been greatly affected by the coronavirus disease 2019 (COVID-19) pandemic. OBJECTIVE: We have piloted a new model for tracking patients and providing rehabilitation guidance that uses WeChat. The purpose of this study is to explore the role of chat software in rehabilitation guidance for hip fracture patients during COVID-19. METHODS: Patients treated for hip fractures from February 1 to April 30, 2020 were randomly divided into a control group and an observation group. The control group was given conventional discharge guidance, while the observation group also followed up the patients using WeChat to guide the exercise. Satisfaction, the Harris Hip Score, complications and the mortality of the two groups after discharge were compared. RESULTS: The incidence of complications and mortality in the observation group were significantly lower than in the control group: p= 0.022 and p= 0.048, respectively. The Harris Hip Score and satisfaction were significantly better than the control group's: p= 0.000 and p= 0.007, respectively. CONCLUSION: During the COVID-19 pandemic, it is very helpful to use WeChat software or other social software with similar functions (such as WhatsApp and Facebook) to guide the rehabilitation of hip fractures.

The Potential Diagnostic Accuracy of Circulating MicroRNAs for Leukemia: A Meta-Analysis.

BACKGROUND: Leukemia is a common malignant disease in the human blood system. Many researchers have proposed circulating microRNAs as biomarkers for the diagnosis of leukemia. We conducted a meta-analysis to evaluate the diagnostic accuracy of circulating miRNAs in the diagnosis of leukemia. METHODS: A comprehensive literature search (updated to October 13, 2020) in PubMed, EMBASE, Web of Science, Cochrane Library, Wanfang database and China National Knowledge Infrastructure (CNKI) was performed to identify eligible studies. The sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the curve (AUC) for diagnosing leukemia were pooled for both overall and subgroup analysis. The meta-regression and subgroup analysis were performed to explore heterogeneity and Deeks' funnel plot was used to assess publication bias. RESULTS: 49 studies from 22 publications with a total of 3,489 leukemia patients and 2,756 healthy controls were included in this meta-analysis. The overall sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio and area under the curve were 0.83, 0.92, 10.8, 0.18, 59 and 0.94, respectively. Subgroup analysis shows that the microRNA clusters of plasma type could carry out a better diagnostic accuracy of leukemia patients. In addition, publication bias was not found. CONCLUSIONS: Circulating microRNAs can be used as a promising noninvasive biomarker in the early diagnosis of leukemia.

A holistic understanding of cobalt cycling and limiting roles in the eutrophic Lake Taihu.

Cobalt (Co) cycling is often dominated by its role as a micronutrient in marine, while little is known on its cycling in a shallow eutrophic lake. Monthly sampling was performed in eutrophic Meiliang Bay of Lake Taihu, combining two laboratory control experiments and in situ Co limitation bioassay experiments. The high-resolution dialysis and the diffusive gradients in thin films technique were used to detect dissolved and labile Co, respectively. The positive correlations between dissolved/labile Co and Mn in the sediments for 6 or 7 months demonstrated that the mobility of Co in the sediments was primarily controlled by Mn redox cycling in the field. However, it is unexpected that the dissolved and labile Co only showed a small change over one year irrespective of the significant fluctuation in dissolved/labile Mn, with the concentrations being as low as 1.08 ± 0.22 µg/L and 0.246 ± 0.091 µg/L for dissolved and labile Co in the surface 20 mm sediment, respectively. Cyanobacterial bloom simulation and aerobic-anaerobic-cyanobacterial addition experiments indicated that the level of Co in the sediment-overlying water system was strongly regulated by cyanobacterial uptake, followed by the degradation of Co-enriched cyanobacterial biomass, which offset the influence of Mn redox cycling on Co mobility in the sediment. The significant enhancement of Microcystis spp. biomass by Co addition further indicated that Co was the potential limiting nutrient for cyanobacterial blooms. This work provides new ideas for better management strategies of eutrophication in shallow lakes.

Laboratory investigation on calcium nitrate induced coupling reactions between nitrogen, phosphorus, sulfur, and metals in contaminated sediments.

In recent years, calcium nitrate addition has become a promising and usually used method for in situ sediment remediation. In this study, excess calcium nitrate was applied to column sediments to explore the coupling reactions of elements such as N, Fe, S, and P. Diffusive gradients in thin film (DGT) devices were used to collect labile substances at the sediment-water interface. Rhizon samplers were used to collect soluble substances in interstitial water. Results showed that nitrate addition turned the surface sediment into a more oxidized state, and mobile Fe, S, P, and As were removed in surface ~ 10-cm sediment. Due to different nitrate distributions in corresponding sediment depths, the consumption rates of NH3-N and soluble reactive P were faster in the surface sediment than that in deeper layers. Different from previous researches, the transient increase of soluble Fe was observed in this study, which was probably attributed to the solvation of FeS in the autotrophic denitrification process. According to our results, we suggest that a dosage of far less than 141 g N/m2 and slightly more than 45.3 g N/m2 can be used for the remediation of black and odorous sediment and control of internal P by calcium nitrate.

Potential diagnostic value of circulating miRNA for multiple myeloma: A meta-analysis.

BACKGROUND: Multiple myeloma (MM) is the second incurable hematological malignancy. In recent years, due to the rise of microRNA (miRNA), many scholars have participated in the study of its value in the diagnosis of MM, and have obtained good but inconsistent results. Therefore, in order to determine the role of miRNA in the early diagnosis of MM, we performed this meta-analysis. METHODS: We searched for related studies including PubMed, Web of Science, EMBASE, Cochrane Library, China National Knowledge Infrastructure (CNKI) and Wanfang Database as of July 20, 2020 to conduct this meta-analysis. To improve the accuracy, the quality assessment of Diagnostic Accuracy Study 2 (QUADAS-2) was used. We also applied random effects models to summarize sensitivity and specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and area under the curve (AUC) to measure diagnostic values, and subgroup analysis used to discover potential sources of heterogeneity. RESULTS: We finally collected 32 studies from 15 articles that included a total of 2053 MM patients and 1118 healthy controls in this meta-analysis. The overall sensitivity, specificity, PLR, NLR, DOR and AUC were 0.81, 0.85, 5.5, 0.22, 25 and 0.90, respectively. Subgroup analysis shows that the down-regulation of microRNA clusters with larger samples size of plasma type could carry out a better diagnostic accuracy of MM patients. In addition, publication bias was not found. CONCLUSIONS: Circulating miRNA could be a potential non-invasive biomarker for early diagnosis of MM. However, multi-center, more rigorous, and larger-scale studies are needed to verify our conclusions.

Potential diagnostic value of miRNAs in peripheral blood for osteosarcoma: A meta-analysis.

Osteosarcoma (OS) is one of the most common primary malignant tumors in adolescents. In recent years, multiple studies have reported the value of miRNAs in the diagnosis of OS, but the results were very different from each other. Therefore, we conducted this meta-analysis to determine the accuracy of miRNAs in the diagnosis of OS. The meta-analysis searched for relevant researches including PubMed, EMBASE, Web of Science, Wanfang database and China National Knowledge Infrastructure (CNKI) as of June 1, 2020. We used the quality assessment of Diagnostic Accuracy Study 2 (QUADAS-2) to score the quality of each study. A random effects model was used to pool the sensitivity and specificity. We measured the diagnostic value using positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and area under the curve (AUC). Subgroup and meta-regression analysis were used to find potential sources of heterogeneity. The meta-analysis finally included 31 articles about 2634 OS patients and 1715 healthy controls. The pooled estimations showed that the circulating miRNAs has a high accuracy in diagnosing OS, with a sensitivity of 0.79, specificity of 0.89, PLR of 7.3, NLR of 0.23, DOR of 31, and AUC of 0.90. In addition, subgroup and meta-regression analysis showed that miRNA clusters have higher diagnostic accuracy than single miRNA, and miRNAs in plasma were more reliable than those in serum. In conclusion, peripheral blood miRNA is a potential noninvasive biomarker to assist in the early diagnosis of OS, especially young patients with bone pain and/or indeterminate radiology findings.

A comprehensive understanding of enhanced Pb mobilization in sediments caused by algal blooms.

A good understanding of lead (Pb) mobilization in eutrophic lakes is a key to the accurate assessment of Pb pollution. In this work, dissolved and labile Pb was determined by both high resolution dialysis (HR-Peeper) and diffusive gradients in thin films (DGT) in sediment-water profiles of the hyper-eutrophic Meiliang Bay of Lake Taihu on a monthly basis during one year. The drinking water standards for dissolved Pb of the World Health Organization (10µg/L) and those of China were exceeded in the overlying water (20.79-118.5µg/L). Out of which, a total of five months even exceeded the fisheries water quality limitation (50µg/L) in China. The algal blooms created an anaerobic environment in the surface sediments in July. The reductive conditions led to the dissolution of Fe/Mn and this caused the release of Pb, followed by organic matter complexation. This was supported by the coincident changes of dissolved Pb with dissolved organic matter (DOM) in sediments under anaerobic incubation. Algae residue decomposition in October caused another distinct release of Pb, but this process should be considerably suppressed by increased sulfide precipitation and pyrite adsorption of Pb ion. These results indicated that Pb mobilization in sediments can be significantly enhanced by algal blooms in eutrophic lakes, indicating that further attention should be paid to Pb pollution in waters with harmful algal blooms.

Mobility of chromium in sediments dominated by macrophytes and cyanobacteria in different zones of Lake Taihu.

To study the mechanisms of chromium (Cr) mobilization in sediments of lakes with different ecotypes, seasonal sampling was performed in the macrophyte-dominated East Taihu (MDET) and cyanobacteria-dominated Meiliang Bay (CDMB) in Lake Taihu. Concentrations of labile Cr(VI) and dissolved Cr were assessed using diffusive gradients in thin films (DGT) and high-resolution dialysis passive sampling devices, respectively. Results indicated that in pore water the dissolved Cr concentrations and in sediments total Cr and Cr fractions concentrations (dissolved, exchangeable and carbonate fraction (F1), Fe-Mn oxide fraction (F2), organic/sulfide fraction (F3)) were lower in MDET than in CDMB. However, the highly toxic DGT-labile Cr(VI) concentrations were higher in MDET sediments than in CDMB sediments. In the two lake zones, the seasonal variations in concentrations of dissolved Cr and DGT-labile Cr(VI) were significant, while total Cr and Cr fractions showed negligible changes (except F1 fraction). In summer, the high mobility of dissolved Cr (MDET: 103.42±10.82µg/L; CDMB: 108.99±4.24µg/L) were mainly caused by dissolved organic matter complexing with Cr(III). In winter the high mobility of dissolved Cr (MDET: 100.27±22.04µg/L; CDMB: 102.01±8.81µg/L) and DGT-labile Cr(VI) (MDET: 28.26±3.73µg/L; CDLZ: 25.82±2.26µg/L) were primarily caused by the oxidization of Cr (III) by Mn(III/IV) oxides. This study establishes the mechanisms for seasonal variation of Cr mobilization in different lake ecological zones, highlighting the urgent need for remediation of Cr pollution, especially in macrophyte-dominated lake zones.

Peak Chromium Pollution in Summer and Winter Caused by High Mobility of Chromium in Sediment of a Eutrophic Lake: In Situ Evidence from High Spatiotemporal Sampling.

To study the mechanisms of chromium (Cr) mobilization in sediments of eutrophic lakes, monthly sampling was performed in the Meiliang Bay of Lake Taihu, China, combined with laboratory experiments. High-resolution dialysis and diffusive gradients in thin film (DGT) sampling techniques were used. Results indicated that in July 2016 and January 2017, the concentrations of soluble Cr and DGT-labile Cr(VI) in the overlying water exceeded both drinking and fishery water quality standards, resulting from the high mobility of Cr in sediments. In July (summer), the high concentration of soluble Cr (134.04 ± 7.20 µg/L) detected in the anaerobic sediments was primarily caused by the complexation of Cr(III) with dissolved organic matter (DOM). This mechanism was supported by an observed simultaneous increase of soluble Cr and DOM under simulated anaerobic conditions. In January (winter), the high concentrations of soluble Cr (97.55 ± 9.65 µg/L) and DGT-labile Cr(VI) (25.83 ± 1.25 µg/L) in aerobic sediments were primarily caused by reoxidation of Cr(III) by Mn(III/IV) oxides as evidenced by the lowest concentrations of soluble and DGT-labile Mn(II). This study sheds light on the full-year variation and mechanisms of Cr mobilization in eutrophic lake sediments and suggests the urgent need for remediation of Cr pollution especially for winter.