Programmed intermittent epidural bolus in parturients: A meta-analysis of randomized controlled trials.

BACKGROUND: To evaluate the efficacy and safety of programmed intermittent epidural bolus (PIEB) in parturients. METHODS: The PubMed, Embase, and the Cochrane Library (from inception to July 2021) were searched for identification of randomized placebo-controlled trials in which PIEB was applied in parturients. The outcomes were the effect of analgesia, satisfaction score, mode of delivery, duration of labor, neonatal condition, and adverse events. The pooled odds ratios (OR), weighted mean difference (WMD), and 95% confidence intervals (CIs) were calculated using random- and fixed-effects models. RESULTS: PIEB was found to be associated with decreased total consumption of ropivacaine (WMD = -15.83, 95% CI: -19.06 to -12.60, P < .00001; I2 = 61%; P for heterogeneity = .04), total consumption of sufentanil (WMD = -4.93, 95% CI: -6.87 to 2.98, P < .00001; I2 = 68%; P for heterogeneity = .05), numbers of patients who require patient-controlled epidural analgesia bolus (OR = 0.27, 95% CI: 0.14-0.51, P < .0001; I2 = 65%; P for heterogeneity = .01), the number of attempts (WMD = -4.12, 95% CI: -7.21 to -1.04, P = .009; I2 = 100%; P for heterogeneity < .00001), rate of breakthrough pain (OR = 0.47, 95% CI: 0.28-0.80, P = .005; I2 = 47%; P for heterogeneity = .09). Eight studies focus on the duration of analgesia. After by meta-analysis, we found that the pain visual analogue scale (VAS) score at 30 minutes, 2 hours, 4 hours, and 5 hours in PIEB group was significantly lower when compared with control group, (WMD = -0.15, 95% CI: -0.26 to -0.04, P = .006; I2 = 0%; P for heterogeneity = .64), (WMD = -0.79, 95% CI: -1.32 to 0.25, P = .004; I2 = 97%; P for heterogeneity < .00001), (WMD = -1.00, 95% CI: -1.08 to -0.91, P < .00001; I2 = 0%; P for heterogeneity = .67), (WMD = -1.81, 95% CI: -3.23 to -0.39, P = .01; I2 = 98%; P for heterogeneity < .00001), respectively. Nineteen studies discussed the mode of delivery between 2 groups. The results suggest that the rate of normal delivery is significantly higher in PIEB group compared with control group (OR = 1.37, 95% CI: 1.08-1.75, P = .01). The time of first and second stage of labor are significantly shorter in PIEB group compared with control group, the result is (WMD = -10.52, 95% CI: -14.74 to 4.76, P < .00001; I2 = 0%; P for heterogeneity = .86), (WMD = -1.48, 95% CI: -2.26 to -0.69, P = .0002; I2 = 35%; P for heterogeneity = .10), respectively. Thirteen studies concerned the satisfaction score of patients. The satisfaction score of patients in the PIEB group was significantly higher when compared with control group (WMD = 0.91, 95% CI: 0.42-1.39, P = .0003; I2 = 98%; P for heterogeneity < .00001). The Apgar score at 1, 5 minutes in PIEB group are significantly higher (WMD = 0.07, 95% CI: 0.02-0.13 P = .007; I2 = 55%; P for heterogeneity = .04), (WMD = -0.08, 95% CI: -0.12 to -0.05, P < .00001; I2 = 21%; P for heterogeneity = .27), respectively. CONCLUSIONS: PIEB is a good alternative for labor analgesia with better analgesic effect, maternal and infant outcome.

[Characterizing Sources and Composition of Chromophoric Dissolved Organic Matter in a Key Drinking Water Reservoir Lake Tianmu].

Lake Tianmu is an important source of drinking water, and its water quality can influence ecosystem service functions. Unraveling the sources and composition of chromophoric dissolved organic matter (CDOM) that can affect water treatment processes is necessary to maintain water supply safety and ecosystem service functioning of Lake Tianmu. Samples were collected monthly in 2017 and analyzed for CDOM absorbance and fluorescent spectra using parallel factor analysis (PARAFAC) to investigate the spatial and temporal variations of CDOM sources and composition in Lake Tianmu. PARAFAC results showed that CDOM in Lake Tianmu was mainly composed of a microbial humic-like component C1 (44.2%±9.8%), followed by a tryptophan-like component C2 (29.2%±4.3%), tyrosine-like component C3 (17.2%±13.1%), and terrestrial humic-like component, C4 was the lowest (9.4%±2.4%). The CDOM abundance a(254) and fluorescence intensities of C1 and C2 were significantly higher in the river mouths than in the downstream lake regions, whereas the spectral slope S275-295 was significantly lower in the river mouths (t-test, P<0.05), indicating that allochthonous inputs cause an elevated degree of humification and relative increase in the molecular weight of CDOM in the inflowing river mouths. Seasonal differences in CDOM composition were mainly ascribed to the a(254) and fluorescence intensities of C1, C2, and C4 being significantly higher in the summer and autumn than in the winter and spring (t-test, P<0.05). Our results showed that the influences of different seasons on CDOM composition comprise differences in rainfall and runoff input, as well as water temperature, thermal stratification, phytoplankton biomass, and mineralization of CDOM by light and microbes.

[Effect of Phytoplankton Community Composition and Size Structure on Light Absorption Properties].

In the fields of phytoplankton ecology, water optics, and water color remote sensing, phytoplankton absorption properties represent the light absorption capacity of phytoplankton, which affects photosynthesis efficiency and carbon fixation. Here, the biomass, community composition, and the absorption properties of phytoplankton were measured alongside other bio-optical parameters in Lake Tianmu are examined using data collected between January and November 2013 (except February). Based on the relationships between phytoplankton biomass, community composition, and absorption, the effects of abundance, biomass, and equivalent sphere diameter on phytoplankton absorption and specific absorption were revealed. The highest biomass and abundance of phytoplankton were recorded in the autumn and the lowest in the winter. Cryptomonas, Synedra, and Cyclotella were the dominant genera throughout the year. The dominant genera structure type was Bacillariophyta-Cryptophyta in the winter and spring, Bacillariophyta-Chlorophyta-Pyrroptata in the summer, and Cryptophyta-Bacillariophyta-Chlorophyta in the autumn. Phytoplankton diameter was ranked in the order summer>autumn>winter>spring, with mean values of 64.83 µm in summer and 29.54 µm in spring. Phytoplankton absorption coefficients of were ranked in the order autumn > spring > winter > summer, with mean values at 440 nm and 675 nm of (0.66±0.18) m-1 and (0.33±0.10) m-1 in autumn and (0.17±0.02) m-1 and (0.08±0.01) m-1 in summer, respectively. The specific absorption coefficients of the phytoplankton were ranked in the order spring > winter > autumn > summer, with mean values at 440 nm and 675 nm of (0.07±0.02) m2·mg-1 and (0.04±0.01) m2·mg-1 in spring and (0.03±0.004) m2·mg-1 and (0.01±0.002) m2·mg-1 in summer, respectively. Significant linear correlations were found between phytoplankton biomass, abundance, and absorption coefficients. Variations of Bacillariophyta and Cyanophyta biomass caused by temperature explained the seasonal variation in absorption coefficients. The specific absorption coefficient decreased with an increase in equivalent sphere diameter, and variations in phytoplankton community composition explained seasonal changes in the specific absorption coefficient.

Creating rat hepatocyte organoid as an in vitro model for drug testing.

BACKGROUND: Liver organoids have recently been applied as models for liver disease and drug screening, especially when combined with liver-on-a-chip technologies. Compared to hepatocyte-like cells, primary hepatocytes have high functionality but cannot maintain their function when cultured in vitro. Mesenchymal stem cells (MSCs) enhance hepatocyte function and maintain hepatocyte metabolism when co-cultured with hepatocytes. MSCs can help induced pluripotent stem cells to generate an organoid structure via the MSC-based traction force triggered by extracellular matrix (ECM) proteins. In this study, primary hepatocytes were co-cultured with MSCs on a liver-derived ECM to generate liver organoids within a short duration. AIM: To create hepatocyte organoids by co-culturing primary hepatocytes with MSCs on a porcine liver extracellular matrix (PLECM) gel. METHODS: Perfusion and enzymatic hydrolysis were used to form the PLECM gel. Rat hepatocytes and human MSCs were mixed and plated on pre-solidified PLECM gel in a 48-well plate for 48 h to generate organoids. Generated organoids were evaluated through hematoxylin and eosin, periodic acid-Schiff, immuno-histological, and immunofluorescence staining, and quantitative PCR for alb, CYP450 gene markers, and urea cycle genes. Culture medium was collected to detect albumin (ALB) and urea production on days 2, 4, 6, 8, 14, and 20. RESULTS: The whole porcine liver was perfused and enzymatically hydrolyzed to form a PLECM gel. The structural components and basement membrane composition of the ECM, such as collagen type I, collagen type IV, fibronectin, and laminin, were demonstrated to be retained. Through interaction of human MSCs with the liver-derived ECM, primary hepatocytes and human MSCs assembled together into a 3D construction and generated primary hepatocyte organoids for 48 h. The mRNAs of the gene alb, the CYP450 gene markers cyp1a1, cyp1a2, and cyp3a2 as well as urea cycle genes arg-1, asl, ass-1, cps-1, nags were highly expressed in hepatocyte organoids. Long-term survival of the primary hepatocyte organoids, as well as stable functionality, was demonstrated via ALB and urea production in vitro. CONCLUSION: Our new method of creating primary hepatocyte organoids by co-culturing hepatocytes with MSCs on liver-derived ECM hydrogels could be used to develop models for liver disease and for drug screening.

Highly sensitive and wide-detection range pressure sensor constructed on a hierarchical-structured conductive fabric as a human-machine interface.

With the booming development of flexible pressure sensors, the need for multifunctional and high-performance pressure sensor has become increasingly important. Although great progress has been made in the novel structure and sensing mechanism of the pressure sensor, the trade-off between the sensitivity and the wide-detection range has prevented its development, further restricting its application in wearable human-machine interfaces (WHMIs). Herein, a novel pressure sensor based on the hierarchical conductive fabric was fabricated and purposed as a WHMI. Poly(3,4-ethylenedioxythiophene) nanowires (PEDOT NWs) and cellulose nanofibers (CNF) were stacked on a conductive poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) fabric to form a special spatial multi-level hierarchical structure inside the fabric, which is a breakthrough for the improvement of the sensor's performance and makes the fabrication process of in situ polymerization suitable for large-scale production. The multi-level hierarchical structures endowed the pressure sensor with characteristics of high sensitivity (15.78 kPa-1), a wide-detection range from 30 Pa to 700 kPa, and outstanding stability toward compression and bending deformation. Benefiting from its excellent performance, a human-machine interface based on arrayed pressure sensors and signal processing system can control the illumination of the LED array and effectively capture finger motion to control the eight-direction movement of an unmanned aerial vehicle (UAV). This improved performance of the pressure sensor based on the hierarchical conductive fabric made it a widespread application in intelligent fabric, electronic skin, human-machine interfaces, and robotics.

[Bioavailability Characteristics of Chromophoric Dissolved Organic Matter in Lake Gaoyou, Lake Nansi, and Lake Dongping Under Different Hydrological Scenarios].

The bio-lability of chromophoric dissolved organic matter (CDOM) directly reflects its biodegradability potential, and also affects the migration and conversion of pollutants and impacts water quality. This study combines excitation-emission matrices and parallel factor analysis (EEMs-PARAFAC) with laboratory 28 days of bio-incubation experiments, and analyzed the bioavailability characteristics of CDOM samples collected from Lake Gaoyou, Lake Nansi and Lake Dongping in flood season and dry season. Our results showed that:① four fluorescent components were obtained using EEMs-PARAFAC, including a microbial humic-like C1, a terrestrial humic-like C4, a tryptophan-like C2, and a tyrosine-like C3. ② The differences of CDOM absorption pre-and post-incubation, i.e. Δa(254) of the three lakes were positive in the three lakes in the flood season, while partially negative in the dry season, indicating a quite different response of CDOM bioavailability to hydrological seasons. ③ Under different hydrological scenarios, the two humic-like components C1 and C4 increased post-bio-incubation compared with that pre-incubation for the samples collected from Lake Nansi and Lake Dongping, and the two protein-like components in Lake Nansi in both the flood and dry seasons and in Lake Dongping in the flood season (t-test, P<0.001, P=0.005) were lower in the post-than those pre-incubation. In Lake Gaoyou, C1-C3 post-incubation were significantly lower than pre-incubation (t-test, P=0.008, P=0.005). In the dry season, in comparison, C1-C4 except for C2 increased post-incubation than pre-incubation for Lake Gaoyou. This indicated that the protein-like components are unstable and more easily uptaken by microorganisms and may be potentially converted into more stable humic-like components. HIX and IC:IT of the three lakes increased post-incubation while the spectral slope S275-295 decreased, which further confirmed the aforementioned conclusion. ④ During both the flood and dry seasons, the bioavailability of the protein-like components C2-C3 and the fluorescence intensity of C1 and C4 in the inflowing river mouths of the three lakes were higher than in the remaining lake regions. It is therefore necessary to strengthen the water quality management in the inflowing river mouths of the three lakes to maintain the water quality of the lakes.

[Response of Chromophoric Dissolved Organic Matter Dynamics to Different Hydrological Scenarios in the Two Largest Freshwater Lakes Connected to the Yangtze River].

Poyang Lake and Dongting Lake are the two largest freshwater lakes in China connected to the Yangtze River. Changes in the water quality of the two lakes are critical to the water security of the residents surrounding the lakes. Analyses of the optical properties, including chromophoric dissolved organic matter (CDOM) absorption and fluorescence spectroscopy coupled by parallel factor analysis (PARAFAC), were carried out to investigate the dynamics of CDOM in the two lakes in different hydrological scenarios. Our results indicated that different hydrological scenarios have more notable effects on the CDOM dynamics in Poyang Lake compared to those in Dongting Lake. In Poyang Lake, the mean CDOM absorption a(254) and dissolved organic carbon (DOC) were higher in the wet season than in the dry-to-wet transition season, and higher still than in the dry season (t-test, P<0.01), and the mean of the CDOM absorption spectral slope S275-295 was higher in the dry season than in the dry-to-wet transition season and higher still than in the wet season (t-test, P<0.01). In Dongting Lake, the mean of a(254) was not significantly different between different hydrological periods, and SUVA254 reached its maximum in the dry-to-wet transition season. Four fluorescent components were identified using parallel factor analysis. The contribution percentage of CDOM protein-like components in the two lakes was higher during the dry season, and the protein-like components and humic-like components contributed roughly the same amount in the dry-to-wet season, whereas the humic-like components accounted for the main proportion in both lakes during the wet season. From the perspective of spatial distribution, the fluorescence intensity of the four components of Poyang Lake was lower in the southern upstream than in the northern downstream lake regions during the dry season, whereas in the wet season a contrast pattern was found, i.e., with high values found in the upstream lake regions. The spatial difference of fluorescence intensity of the four components in the east of Dongting Lake during the dry season was greater than that in the wet season. We found that DOC increased with increasing water level (r2=0.99, P<0.01) in Poyang Lake and tryptophan-like C2 decreased with increasing water level (r2=0.99, P<0.05) in Dongting Lake. Therefore, the water quality of the two lakes should be managed in a targeted manner according to the response characteristics of CDOM in the two lakes under different hydrological scenarios.

[Characterizing Chromophoric Dissolved Organic Matter in Key Lakes in the Middle Reaches of the East Route of the South-North Water Diversion Project].

Lake Hongze and Lake Luoma are two key lakes located in the middle reaches of the east line of the South-to-North Water Diversion Project. We attempted to unravel the sources and optical composition of CDOM for samples collected from these lakes using excitation-emission matrices (EEMs) and parallel factor analysis (PARAFAC). ① Three fluorescent components were obtained using PARAFAC, including a terrestrial humic-like C1, a tryptophan-like C2, and a tyrosine-like C3. The sources and optical composition of CDOM in the two lakes were, to a large extent, affected by upstream inflow. ② Specifically, fluorescence intensity (Fmax) of the three components C1-C3 in the inflowing river mouths of the two lakes was notably higher than in the other lake regions, and Fmax of the three components during the flood season was significantly higher than during the dry season (t-test, P<0.01). During the flood season, the fluorescence intensity of the terrestrial humic-like component was the highest. This indicates that the source and composition of CDOM in the two lakes are greatly affected by the inflow from the upstream water system, and that the hydrological processes control the abundance and sources of CDOM, especially the terrestrial humic-like C1.③ Significant positive relationships were found between the terrestrial humic-like C1 and the DOC concentrations and CDOM absorption a(254) (r2=0.60, P<0.01; r2=0.88, P<0.01), and the correlation was higher than the other two components. This indicated that the terrestrial humic-like component was the main source of CDOM. In addition, the terrestrial humic-like C1 had a significant positive correlation with SUVA, S275-295, and the integration ratio of the fluorescence peak C to peak T (IC:IT) (r2=0.49, P<0.01; r2=0.61, P<0.01; r2=0.93, P<0.01). It is further revealed that the source and composition of CDOM in the two lakes are greatly affected by land sources. This study reveals the response of CDOM source and composition in Lake Hongze and Lake Luoma to different hydrological scenarios and water transfer processes. Based on these results, the water quality management of the rivers entering the lake should be strengthened during the flood season.

[Spatio-temporal Variations in Aquatic Vegetation Cover and the Potential Influencing Factors in Lake Hongze Based on MODIS Images].

Aquatic vegetation is an important part of lake ecosystems and plays a vital role in improving water quality and maintaining biodiversity. At present, China's lakes are facing eutrophication and the degradation of aquatic vegetation. The monitoring of temporal and spatial variations in aquatic vegetation and elucidating the main influencing factors are of great significance for protecting aquatic vegetation and restoring eutrophic lake ecosystems. Therefore, we introduced the Vegetation Present Frequency (VPF) method to extract data on aquatic vegetation and combined this with meteorological factors and human activities to analyze the temporal and spatial in Lake Hongze based on MODIS data from 2007 to 2017. The VPF of aquatic vegetation in Lake Hongze showed clear seasonal and interannual variations. The VPF was significantly higher in spring and summer than in autumn and winter (P<0.05, one way-ANOVA). The maximum VPF of 0.43 occurred in June but the minimum VPF of 0.21 was recorded in January. The VPF from April to October, during the growing season of aquatic vegetation, was significantly higher than in other months. The annual mean VPF of the northern lake area (Z1) decreased significantly (R2=0.56, P<0.01), ranging from the highest value of 0.50 in 2008 to the lowest value of 0.27 in 2016 (a decrease of 45.8%), indicating a significant loss of aquatic vegetation. Spatially, the VPF of Lake Hongze decreases from the coastal zone to the open water, and the VPF values of the northern (Z1) and western sub-lakes (Z2) are higher than that of other lakes segments (Z3-Z5). The interannual variation in VPF for the entire lake was not significantly affected by annual mean temperature, annual precipitation, annual mean wind speed, or annual sunshine duration (P>0.05), indicating that meteorological factors have little influence on interannual variation of aquatic vegetation in this lake. However, total suspended matter concentration was significantly negatively correlated with VPF in Z1 area (R2=0.48, P<0.01), with strong sand-mining activities occurring in this area. These results indicate that the increase of total suspended matter concentrations caused by sand mining is an important driving factor in the decline of aquatic vegetation in the Z1 segment.

Krüppel-like factor 3 inhibition by mutated lncRNA Reg1cp results in human high bone mass syndrome.

High bone mass (HBM) is usually caused by gene mutations, and its mechanism remains unclear. In the present study, we identified a novel mutation in the long noncoding RNA Reg1cp that is associated with HBM. Subsequent analysis in 1,465 Chinese subjects revealed that heterozygous Reg1cp individuals had higher bone density compared with subjects with WT Reg1cp Mutant Reg1cp increased the formation of the CD31hiEmcnhi endothelium in the bone marrow, which stimulated angiogenesis during osteogenesis. Mechanistically, mutant Reg1cp directly binds to Krüppel-like factor 3 (KLF3) to inhibit its activity. Mice depleted of Klf3 in endothelial cells showed a high abundance of CD31hiEmcnhi vessels and increased bone mass. Notably, we identified a natural compound, Ophiopogonin D, which functions as a KLF3 inhibitor. Administration of Ophiopogonin D increased the abundance of CD31hiEmcnhi vessels and bone formation. Our findings revealed a specific mutation in lncRNA Reg1cp that is involved in the pathogenesis of HBM and provides a new target to treat osteoporosis.

[Influence of Cyanobacterial Blooms on Denitrification Rate in Shallow Lake Taihu, China].

Denitrification is the most important nitrogen removal process in lake waters, and is of great significance for mitigating nitrogen pollution and controlling eutrophication in lakes. The outbreak and decline of cyanobacterial blooms may promote denitrification directly in the water column by changing the nitrogen circulation pathway and microenvironment of the water body, and accelerate the removal of nitrogen. In order to verify this hypothesis, the cyanobacteria with different biomass and the NO3--N, PO43--P nutrient for 10 days were taken from Taihu Lake water to simulate the effects of cyanobacteria growth and degradation on denitrification. The dynamic changes of algal biomass and various forms of nitrogen concentration were simultaneously determined by 15N isotope addition culture combined with membrane inlet mass spectrometer (MIMS) for real-time quantitative determination of denitrification rate. The results showed that cyanobacteria absorbed nitrogen into particle nitrogen during the growth period. During the decay period, algae cells released a large amount of NH4+-N by degrading mineralization, which was then converted into NO3--N to provide a substrate for denitrification. That is the key to promoting denitrification in water; the denitrification rate (as N2) reaches (1614.52±301.57)µmol·(m2·h)-1, which is three times higher than the denitrification rate[ (534.45±242.18)µmol·(m2·h)-1]of the lowest concentration cyanobacterial group at the same time. At the end of the experiment, the highest rate of TN removal was highest in the group with the highest initial biomass of cyanobacteria (40.02%), which was 2.26 times of the TN removal rate (17.72%) in the control, indicating that cyanobacterial accumulation can significantly promote the intensity of denitrification and accelerate the removal of nitrogen in water. The rate of denitrification in the decline of cyanobacteria is significantly affected by the concentration of NH4+-N, indicating that the coupling of nitrification-denitrification of microorganisms attached to algae is the main route of nitrogen removal. The results study indicate that the cyanobacteria bloom rapidly during the growth period. Nitrogen is converted into particle nitrogen. The degradation of cyanobacteria is accelerated by coupled nitrification-denitrification, which may be one of the reasons for the decrease of nitrogen concentration in Taihu Lake.

[Reconstruction of Water Hyperspectral Remote Sensing Reflectance Based on Sparse Representation and Its Application].

Multispectral satellite sensors have several limitations with respect to capturing the target's spectral information due to their band setting and number of bands. The hyperspectral reconstruction technique is an effective method to obtain hyperspectral information from multispectral data. In this study, we propose a hyperspectral reconstruction algorithm based on the sparse representation of water remote sensing reflectance. The proposed algorithm was validated for five ocean color sensors (Sentinel-2A MSI, MERIS, MODIS Aqua, GOCI, and ⅦRS) using in situ measured above-water remote sensing reflectance. The mean absolute percentage error (MAPE) and root mean square error (RMSE) of the reconstructed and measured spectra for five ocean color sensors were less than 10% and 0.005 sr-1, respectively. Compared with the spectra reconstruction algorithm based on multi-variable linear regression, the proposed algorithm can obtain the features of complex water remote sensing reflectance without using in situ-measured reflectance for algorithm tuning. In addition, the accuracy of the proposed algorithm is better than the spectra reconstruction algorithm based on multi-variable linear regression. Two spectra reconstruction algorithms were applied to five ocean color sensors to test the applicability of the remotely estimated water constituent concentration. The statistical results for the reconstructed spectral factors and in situ water constituent concentration suggest that the reconstructed reflectance derived by the proposed algorithm has a performance similar to that of in situ-measured hyperspectral reflectance. The reconstructed reflectance derived by the proposed algorithm performs better than the spectra reconstruction algorithm based on multi-variable linear regression. Finally, the proposed algorithm was applied to GOCI data to remotely estimate the chlorophyll-a and total suspended matter concentrations. The accuracy of the water constituent concentration estimated from reconstructed images is better than that using original multispectral images. For the estimation of the chlorophyll-a concentration, the MAPE improved from 80.6% to 51.5% and the RMSE improved from 12.175 µg·L-1 to 7.125 µg·L-1. For the estimation of total suspended matter, the MAPE improved from 19.1% to 18.8% and the RMSE improved from 29.048 mg·L-1 to 28.596 mg·L-1.

[Response of Chromophoric Dissolved Organic Matter Composition to Different Hydrological Scenarios in Large Eutrophic Lake Taihu].

Chromophoric dissolved organic matter (CDOM) is a fraction of dissolved organic matter that can strongly absorb light in the ultraviolet and blue regions and plays an important role in the biogeochemical cycling of carbon, nitrogen, and phosphorus. Unraveling the sources, optical composition, and corresponding spatial variabilities of CDOM can improve our understanding of carbon, nitrogen, and phosphorus cycling in lakes and lake water quality management. CDOM spectral absorption and fluorescent excitation-emission matrices were measured to investigate the compositional dynamics of CDOM under different hydrological scenarios. Our results showed that the mean value of dissolved organic carbon (DOC) concentration of (8.11±1.26) mg·L-1 in the rainy season was significantly higher than that in the dry season (3.53±1.19) mg·L-1 (t-test, P<0.01), whereas the mean spectral slope S275-295 of (20.89±1.90) µm-1 in the dry season was significantly greater than that in the rainy season (19.09±1.81) µm-1 (t-test, P<0.001). Three fluorescent components were identified using parallel factor analysis, and we further found that the dynamics of the three CDOM components were strongly influenced by hydrological conditions. Fluorescence intensity (Fmax) of the terrestrial humic-rich component C2 increased with increasing water levels and rainfall. Significant negative relationships were found between all three fluorescent components and dissolved oxygen (P<0.01), suggesting that all three components served as important substrates for microbial processing. Significant positive relationships were found between the terrestrial humic-rich C2 and tryptophan-like C1 and chlorophyll-a and chemical oxygen demand, indicating that anthropogenic inputs and algal degradation contributed significantly to the CDOM pool in Lake Taihu. We further found a significant positive relationship between DOC concentration and Fmax of terrestrial humic-rich C2 (r2=0.58, P<0.001), suggesting that DOC in Lake Taihu was primarily derived from allochthonous input.

[Efficacy of Phoslock® on the Reduction of Sediment Phosphorus Release in West Lake, Hangzhou, China].

Famous as the world cultural heritage, West Lake in Hangzhou city has plenty of soft sediments with high organic matter content. To search the countermeasures for internal phosphorus release reduction from the sediment, the sediment core incubation was conducted to understand the efficacy of Phoslock® on internal phosphorus release in spring, summer and winter, respectively. The results showed that the internal phosphorus release fluxes in winter and spring were relatively low, with averaged values in the entire lake of 0.13 mg·(m2·d)-1 and 0.29 mg·(m2·d)-1, respectively, while the release flux was 3.29 mg·(m2·d)-1 in summer, more than ten times higher than those in spring and winter. It was estimated that 23.7 kg of phosphorus could be released from sediment in the entire lake every day in summer. Spatially, the phosphorus release flux was related to organic matter contents in sediments, but not the phosphorus or bioavailable phosphorus contents in sediments in West Lake. With Phoslock® added at the rate of 630 g·m-2, sediment phosphorus release was successfully controlled, which reduced the phosphorus concentration in the lake water to less than 0.010 mg·L-1. Especially during summer time, the sediment phosphorus release was reduced by 98% after Phoslock® application. The research suggested that Phoslock® is powerful for phosphorus control even for sediments with high organic matter content, which could be considered in ecological restoration of WEst Lake.

[Remote sensing estimation of total suspended matter concentration in Xin'anjiang Reservoir using Landsat 8 data].

Total suspended matter (TSM) plays an important role in determining the underwater light climate, which then affects the lake primary production. Therefore, TSM concentration is an important parameter for lake water quality and water environment assessment. This study developed an empirical estimation model and presented the spatial distribution of TSM concentration for the relatively clear Xin'anjiang Reservoir based on the in situ ground data and the matching Landsat 8 data. The results showed that Band 2, Band 3 and Band 8 of Landsat 8 data were the sensitive bands of TSM estimation in Xin'anjiang Reservoir with the linear determination coefficients of 0.37, 0.51 and 0.42, respectively. However, the linear models using Band 2, Band 3 and Band 8 could not give a reasonable and satisfying estimation accuracy. Therefore, a three-band combination estimation model of TSM concentration using Band 2, Band 3 and Band. 8 was calibrated and validated to improve the TSM concentration estimation accuracy. The determination coefficient, mean relative error and root mean square error were 0.92, 11% and 0.16 mg x L(-1), respectively for the three-band combination model. Overall, the TSM concentration was relatively low in Xin'anjiang Reservoir, ranging from 0. 04 to 24. 54 mg x L(-1) with a mean value of 2.19 mg x L(-1). Higher TSM concentrations were distributed in the nearshore zones and small bays such as Fengshuling bay, Fenkou bay, Weiping bay, Anyang bay, Dashu bay and Linqi bay, which were affected by input rivers rainfall and human dredging activity. Therefore, this study demonstrated that the combination of three bands using Landsat 8 data could be used to estimate the TSM concentration in the relatively clear Xin'anjiang Reservoir.

[Estimation of Diffuse Attenuation Coefficient of Photosynthetically Active Radiation in Xin'anjiang Reservoir Based on Landsat 8 Data].

Photosynthetically active radiation (PAR) is defined as the wavelength band of 400 to 700 nm, representing most of the visible solar radiation that could be used for photosynthesis. PAR is attenuated by the absorption and scattering of nonpigment suspended matter, chromophoric dissolved organic matter and phytoplankton, and it plays an important role in determining the density and distribution of aquatic organisms. This study developed an empirical model and presented the spatial-temporal distribution of PAR diffuse attenuation coefficient [Kd (PAR)] for the slightly turbid Xin'anjiang Reservoir based on the in situ ground data and the matching Landsat 8 data. The results showed that the three-hand combinational model of Kd ( PAR) using Band 2, Band 3 and Band 8 could give a reasonable and acceptable estimation accuracy with a determination coefficient of 0. 87. Independent dataset was used to validate the model with a mean relative error of 9.16% and a root mean square error of 0.06 m⁻¹. Therefore, the three-band combination using Landsat 8 data could be used to accurately estimate Kd (PAR) in the slightly turbid Xin'anjiang Reservoir. Kd (PAR) exhibited significant seasonal and spatial differences. Kd (PAR) was higher in autumn (September-November) and summer (June-August) with the average Kd (PAR) of (0.82 ± 0.60) m⁻¹ and (0.77 ± 0.41) m⁻¹, but lower in winter (December-February) and spring (March-May) with the average Kd (PAR) of (0.56 ± 0.50) m⁻¹ and (0.40 ± 0.45 ) m⁻¹, respectively. Spatially, Kd (PAR) ranged from 0.002 to 13.86 m⁻¹ with an average of (0.64 ± 0.49) m⁻¹. The temporal heterogeneity of Kd (PAR) was mainly caused by the seasonal rainfall and seasonal growth of phytoplankton. The spatial heterogeneity was mainly caused by suspended matter concentration derived from watershed inputs and human dredging activity.

[Characteristics of optical absorption coefficients and their differences in typical seasons in Lake Qiandaohu].

Absorption characteristics of total suspended particulate, phytoplankton and tripton in Lake Qiandaohu are presented based on the in situ data collected in winter (from December 2012 to February 2013) and summer (from July to August 2013). The mean values of total suspended particle absorption coefficients at 440 nm [a(p) (440)] in winter and summer are (0.20 +/- 0.07) m(-1) and (0.24 +/- 0.17) m(-1). Correspondingly, the mean values of a(p) (675) are (0.07 +/- 0.02) m(-1) and (0.10 +/- 0.07) m(-1). In winter the absorption spectra of total suspended particulate matters can be divided into two cases: the absorption spectra are similar to those of phytoplankton in the northwest lake and to those of tripton in other lake regions. In summer, the absorption spectra of total suspended particles are similar to those of phytoplankton from 400 nm to 700 nm. The mean values of phytoplankton absorption coefficients at 440 nm [a(ph) (440)] are (0.10 +/- 0.03) m(-1) in winter, and (0.17 +/- 0.14) m(-1) in summer. Accordingly, the mean values of a(ph) (675) are (0.05 +/- 0.02) m(-1) and (0.08 +/- 0.07) m(-1). The mean values of Chlorophyll-specific absorption coefficients (by the concentration of Chla) at440 nm a(*)(ph)(440) are (0.045 +/- 0.010) m2 x mg(-1) in winter and (0.039 +/- 0.013) m2 x mg(-1) in summer. At the same time, the mean values of a(*)(ph) (675) are (0.022 +/- 0.004) m2 x mg(-1) and (0.019 +/- 0.005) m2 x mg(-1). Significantly linear correlations are found between phytoplankton absorption coefficients and chlorophyll a concentration, trophic level index (TLI). Chlorophyll-specific absorption coefficients vary with the chlorophyll a concentrations following a power function. The tripton absorption coefficients exponentially decrease from 400 nm to 700 nm. The correlation between tripton absorption coefficients and inorganic particles is significant in winter, whereas, the correlation between tripton absorption coefficients and the concentrations of total suspended particles and organic particles are significant in summer.

[Characteristics of diffuse attenuation coefficient of underwater irradiance in the lakes in the middle and lower reaches of Yangtze river ].

Based on the underwater irradiance profile measurement and water samples collection in September, October 2007 in Lake Donghu, Lake Liangzi and Lake Honghu, and in April in 2010 in Lake Kuileihu, the diffuse attenuation coefficient and the dominant attenuation factors were analyzed. The ranges of diffuse attenuation coefficient and total suspended solid (TSS), organic suspended solid (OSS), inorganic suspended solid (ISS), chlorophyll a (Chla), and dissolved organic carbon (DOC) concentration varied less in Lake Donghu and Lake Kuileihu than in Lake liangzi and Lake Honghu. The regression analysis showed that ISS was the dominant affecting factor of transparency in Lake Donghu and Lake Kuileihu, but ISS and OSS jointly controlled the transparency in Lake Liangzi and Lake Honghu. The diffuse attenuation coefficient minimum occurred near 580 nm. At around 675 nm, the diffuse attenuation coefficient peak was due to phytoplankton absorption, especially at sites with high pigment concentration. The euphotic depth was less than the mean water depth in Lake Donghu, suggesting that the submerged aquatic vegetation (SAV) can not grow in the present underwater light climate. However, the euphotic depth was larger than the mean water depth in other three lakes showing that the underwater light climate can meet the light requirements for the growth of SAV. The regression analysis showed that ISS was the dominant affecting factor of PAR attenuation in Lake Donghu and Lake Kuileihu, but ISS, OSS and Chla jointly controlled PAR attenuation in lake Liangzi and lake Honghu. The significant correlation between the beam attenuatin coefficient at 750 nm and PAR difffuse attenuation coefficient showed that the particles scattering significantly contributed to underwater irradiance attenuation.

[Characterizing chromophoric dissolved organic matter (CDOM) in Lake Honghu, Lake Donghu and Lake Liangzihu using excitation-emission matrices (EEMs) fluorescence and parallel factor analysis (PARAFAC)].

Little is known about DOM characteristics in medium to large sized lakes located in the middle and lower reaches of Yangtze River, like Lake Honghu, Lake Donghu and Lake Liangzihu. Absorption, fluorescence and composition characteristics of chromophoric dissolved organic matter (CDOM) are presented using the absorption spectroscopy, the excitation-emission ma trices (EEMs) fluorescence and parallel factor analysis (PARAFAC) model based on the data collected in Sep-Oct. 2007 including 15, 9 and 10 samplings in Lake Honghu, Lake Donghu and Lake Liangzihu, respectively. CDOM absorption coefficient at 350 nm a(350) coefficient in Lake Honghu was significantly higher than those in Lake Donghu and Lake Liangzihu (t-test, p< 0. 001). A significant negative correlation was found between CDOM spectral slope in the wavelength range of 280-500 nm (S280-500) and a(350) (R2 =0. 781, p<0. 001). The mean value of S280-500 in Lake Honghu was significantly lower than those in Lake Donghu (t-test, p