Publications by authors named "Shengrui Wang"

63 Publications

Water inflow and endogenous factors drove the changes in the buffering capacity of biogenic elements in Erhai Lake, China.

Sci Total Environ 2021 Sep 14;806(Pt 1):150343. Epub 2021 Sep 14.

Guangdong-Hong Kong Joint Laboratory for Water Security, Center for Water Research, Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, Zhuhai 519087, China; College of Water Sciences, Beijing Normal University, Beijing 100875, China; Engineering Research Center of Ministry of Education on Groundwater Pollution Control and Remediation, Beijing 100875, China.

Buffering capacity could provide a comprehensive view to recognize the response between external loads and water quality and help address the significant challenges associated with the reduction of lake pollution. However, quantification of the dynamic change in the holistic buffering capacity of biogenic elements in lakes and its driving mechanisms has not been fully understood. Taking Erhai Lake in China as an example, this study quantified the long-term (2000-2019) dynamic changes in buffering capacity and revealed key driving forces for the changes in buffering capacity. The results showed that nitrogen buffering capacity (NBC) and organic buffering capacity (CODBC) decreased during the past 20 years, while phosphorus buffering capacity (PBC) did not change significantly. Endogenous factors are the main controlling factors of buffering capacity. Specifically, algal biomass drove the change in NBC (interpretation rate of 62.2%); the adsorption and sedimentation effects of sediments maintained the relative stability of PBC (56.30%) while algal biomass indirectly impacted the PBC (1.69% only) by affecting the redox environment of the sediments; and algae-derived organic matter and refractory organic matter accumulation dominated the change in CODBC (61.4% and 32.8%, respectively). Water inflow is another controlling factor for NBC and CODBC due to dilution of lake water. This study indicated that the accumulation of endogenous loads and a decrease in water inflow drove the decrease in the lake's buffering capacity (mainly NBC and CODBC), which could help explain why the decrease in external loads in Erhai Lake has not yet reversed the trend of water quality decline. Our study highlights the importance of comprehensive buffering capacity improvement instead of simple external load control to optimize lake environmental management. In the future, attention should be given to controlling endogenous loads, especially preventing algal blooms, and to optimizing hydrodynamic conditions to cope with the decrease in water inflow.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2021.150343DOI Listing
September 2021

Synergistic effects of graphene quantum dots and carbodiimide in promoting resin-dentin bond durability.

Dent Mater 2021 10 28;37(10):1498-1510. Epub 2021 Aug 28.

Key Lab. of Oral Diseases Research of Anhui Province, College & Hospital of Stomatology, Anhui Medical University, Hefei 230032, China. Electronic address:

Objective: Resin-based dental adhesion is mostly utilized in minimally invasive operative dentistry. However, improving the durability and stability of resin-dentin bond interfaces remain a challenge. Graphene quantum dots (GQDs) reinforced by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) were introduced to modify the resin-dentin bond interfaces, thereby promoting their durability and stability.

Methods: GQDs, EDC, and EDC+GQDs groups were designed to evaluate the effects of GQDs and EDC on collagenase activity, the interaction of GQDs with collagen, and the resin-dentin interface. First, the effects of GQDs and EDC on collagenase activity was evaluated by Collagenase (EC 3.4.24.3) reacting with its substrate. The interaction of GQDs and EDC with collagen were evaluated by cross-linking degree analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, attenuated total reflection Fourier transform infrared spectroscopy and enzymatic hydrolysis. Second, the acid-etched and rinse adhesive system was used to evaluate the resin-dentin bond on the basis of microtensile bond strength, in situ zymography and fluorescence confocal laser scanning microscopy.

Results: GQDs could inhibit collagenase activity. GQDs with the aid of EDC could cross-link collagen via covalent bonds and improve the anti-enzymatic hydrolysis of collagen. In the resin-dentin adhesion model, the μTBS of the EDC+GQDs group was significantly higher than the other control groups after thermocycling. The addition of EDC to GQDs could inhibit matrix metalloproteinase activity and promote the integrity of the bonding interfaces after thermocycling.

Significance: This study presents a novel strategy to modify the resin-dentin interface and provides a new application for GQDs. This strategy has the potential to improve the durability of resin-based restoration in dentistry.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.dental.2021.07.004DOI Listing
October 2021

Dynamic and driving evolution of lake basin pressure in cold and arid regions based on a new method: A case study of three lakes in Inner Mongolia, China.

J Environ Manage 2021 Nov 11;298:113425. Epub 2021 Aug 11.

Center of Water Research, Beijing Normal University at Zhuhai, 519087, China; Guangdong-Hong Kong Joint Laboratory for Water Security, Zhuhai, 519087, China; Engineering Research Center of Ministry of Education on Groundwater Pollution Control and Remediation, College of Water Sciences, Beijing Normal University, Beijing, 100875, China.

Static single-path assessment methods usually underestimate the lake basin pressure (LBP). Considering the cumulative transmission of multiple paths, how to assess the dynamic changes of LBP and reveal the driving evolution is not clear. Here, taking Hulun, Daihai and Wuliangsuhai lake basins in the cold and arid region as the study case, we established an LBP assessment method that coupled multiple driving paths. For the first time, this study reveals the dynamic and driving evolution of LBP and found that rapid economic development and accelerated urbanization dramatically increased the LBPs in the three lakes. Specifically, the LBPs in the three lake basins has increased by 90%-270 % in the past 32 years, and they experienced a stable stage driven by climate (1987-1992), followed by a slight increasing stage driven by agriculture (1993-2004) and finally a significant increase stage (2005-2018) driven by industry and urbanization. Different degrees of warming, populations and development intensities of agriculture and livestock were the main factors driving the spatial differences in LBPs in the three lake basins. The LBPs in the Hulun, Daihai and Wuliangsuhai Lake Basins exhibited phase driving, continuous driving and ineffective driving characteristics to the water environment changes, respectively, which were related to lake basin governance. Compared with the driving paths of water quality and water quantity, the LBP was most strongly transmitted through the water ecological path. Rapid economic development and accelerated urbanization will bring greater LBPs to the lake basins. Lake management should promote the construction of water environmental protection mechanisms that correspond to urbanization, such as land use, and continue to strengthen watershed governance to alleviate the impact of LBP, especially the impact on the service functions of water ecosystem. Our method quantified the LBPs that were transmitted from different driving paths and provided action priorities for watershed management.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jenvman.2021.113425DOI Listing
November 2021

Trends of the response-relationship between net anthropogenic nitrogen and phosphorus inputs (NANI/NAPI) and TN/TP export fluxes in Raohe basin, China.

Chemosphere 2021 Jul 24;286(Pt 1):131662. Epub 2021 Jul 24.

Key Laboratory of Poyang Lake Environment and Resource Utilization, Ministry of Education, School of Resources Environmental and Chemical Engineering, Nanchang University, Nanchang, 330031, China.

The intensification of anthropogenic nitrogen (N) and phosphorus (P) inputs profoundly affects water environmental quality. Hence it is pivotal to clarify the response relationship between riverine TN/TP export and anthropogenic N/P inputs to provide strategies guidance in N/P management. Based on the variation of net anthropogenic N and P inputs (NANI/NAPI) in the Raohe basin from 1990 to 2018, we constructed the response relationship between NANI/NAPI and total nitrogen and phosphorus (TN/TP) export fluxes in the riverine, which successfully predicted N and P export at the basin scale management. We found N export ratio (ratio of TN export to NANI) increased with slight fluctuation and was mainly affected by the combined effects of Nfer (fertilizer N inputs) and Ndep (atmospheric N deposition) etc., while the decrease of P export ratio (ratio of TP export to NAPI) was mainly due to intensive retention effect of the soil and sediment induced by anthropogenic influence to P transportation process. These results indicate that the downstream aquatic systems take a high risk of increasing N load pressure and the basin systems suffer a danger from rising P load pressure. Therefore, it is recommended to concentrate more on downstream aquatic systems during the N management strategy implementation and pay closer attention to the whereabouts of P in the basin system.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chemosphere.2021.131662DOI Listing
July 2021

Prediction of harmful algal blooms in large water bodies using the combined EFDC and LSTM models.

J Environ Manage 2021 Oct 23;295:113060. Epub 2021 Jun 23.

College of Water Sciences, Beijing Normal University, Beijing, 100875, China.

Harmful algal blooms (HABs) is a worldwide water environmental problem. HABs usually happens in short time and is difficult to be controlled. Early warning of HABs using data-driven models is prospective in making time for taking precaution against HABs. High-frequency water quality monitoring data are necessary to improve the reliability of the model, but it is expensive. This research used environmental fluid dynamics code (EFDC) to extend one-point data obtained by only one instrument to the whole 249 ha water area instead of multi-instruments monitoring, followed by Long short-term memory (LSTM) to predict the HABs in the whole water body. Correlation analysis and principal component analysis were used to reduce the data dimension and improve model accuracy. Finally, the LSTM model was calibrated to predict chlorophyll-a (Chl-a) for the next 1 to 3 time steps. The Nash-Sutcliffe efficiency coefficient (NSE) and mean absolute percentage error (MAPE) of EFDC-LSTM were 0.797-0.991 and 2.74-13.16%, respectively, suggesting the promising utilization of this model in early warning systems for HABs. EFDC-LSTM achieves high-precision HABs forecasting in a cost-effective manner, providing a reliable way to detect HABs in advance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jenvman.2021.113060DOI Listing
October 2021

Implications of phosphorus partitioning at the suspended particle-water interface for lake eutrophication in China's largest freshwater lake, Poyang Lake.

Chemosphere 2021 Jan 14;263:128334. Epub 2020 Sep 14.

Engineering Research Center of Ministry of Education on Groundwater Pollution Control and Remediation, College of Water Sciences, Beijing Normal University, Beijing, 100875, China.

Nutrient partition, especially for phosphorus (P), has been prominently changed that was caused by variation of river-lake relationship during the post-Three Gorges Reservoir and catchment alternations. Changes in proportion of total particulate phosphorus (TPP) and total dissolved phosphorus (TDP) might accelerate lake eutrophication, but limited attention has been paid to P partition over suspended particle (SP) levels. Data analysis showed that SP concentration presented a positive effect on TPP in wet season and soluble reactive phosphorus (SRP) in dry season, indicating seasonal physical and chemical variations. Based on this phenomenon, we proposed a hypothesis that the SP levels would affect TDP and TPP proportions by partition in aqueous-solid. It was found that using the parabola models to fit the sorption relationships of SRP and TDP (R > 0.6, p < 0.01), the maximum sorption capacity (Q) was 64.54 mg/kg and 60.52 mg/kg at 400 mg/L of SP level, respectively. In addition, the partition coefficients (K) of TDP and SRP were logarithmically increased with SP levels, indicating that higher SP levels (>400 mg/L) would hinder the sorption process. Furthermore, enhancing turbulence lead to less sorption of SRP and TDP at high SP levels (>800 mg/L). The sorption of SRP and TDP related to the presence of Fe/Al oxy-hydroxides were enriched in the Fe/Al-P fraction (47% of TP). The findings of this study indicated that the low SP levels would increase P bioavailability for alga and is not conducive for lake eutrophication management.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chemosphere.2020.128334DOI Listing
January 2021

Emerging water pollution in the world's least disturbed lakes on Qinghai-Tibetan Plateau.

Environ Pollut 2021 Mar 9;272:116032. Epub 2020 Nov 9.

Engineering Research Center of Ministry of Education on Groundwater Pollution Control and Remediation, College of Water Sciences, Beijing Normal University, Beijing, 100875, China.

Qinghai-Tibet Plateau (QTP) Lake Region has largest abundance and size distribution of lakes in China. Being relatively away from major human activities, the water quality of these lakes has not attracted concerns in the past. However, dramatic climate change and intensified anthropogenic activities over the past 30 years have exerted multiple pressures on the water environment of the lakes, resulting in elevated nutrient concentrations in major freshwater lakes of the region. Rapid water quality deterioration and eutrophication of the lakes were first found in Lake Hurleg in the northeast of the plateau. Analyses of driving forces associated with these changes indicate that both the intrinsic characteristics of the QTP lakes and climate change were responsible for the vulnerability to human activities than other lakes in different regions of China, with accelerated urbanization and extensive economic development in the lake basin playing a decisive role in creating water pollution events. Under combination pressures from both natural and anthropogenic effect, the increasing rate of nutrient concentrations in Lake Hurleg has been 53-346 times faster than in Lake Taihu and Lake Dianchi during the deterioration stage. The result suggests the current development mode of Lake Hurleg basin is not suitable for setting protection targets for the QTP lake region more broadly due to its extremely poor environmental carrying capacity. To stop worsening the lake water environment condition, it is necessary to review the achievements made and lessons learned from China's fight against lake pollution and take immediate measures, inform policies into the development mode in the QTP lake region, and avoid irreversible consequences and ensure good water quality in the "Asian Water Tower."
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.envpol.2020.116032DOI Listing
March 2021

Rapid regeneration of enamel-like-oriented inorganic crystals by using rotary evaporation.

Mater Sci Eng C Mater Biol Appl 2020 Oct 30;115:111141. Epub 2020 May 30.

Key Lab. of Oral Diseases Research of Anhui Province, College & Hospital of Stomatology, Anhui Medical University, Hefei 230032, China. Electronic address:

Enamel, the hardest tissue in the human body, has excellent mechanical properties, mainly due to its highly ordered spatial structure. Fabricating enamel-like structure is still a challenge today. In this work, a simple and highly efficient method was introduced, using the silk fibroin as a template to regulate calcium- and phosphate- supersaturated solution to regenerate enamel-like hydroxyapatite crystals on various substrates (enamel, dentin, titanium, and polyethylene) under rotary evaporation. The enamel-like zinc oxide nanorod array structure was also successfully synthesized using the aforementioned method. This strategy provides a new approach to design and fabricate mineral crystals with particular orientation coatings for materials.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.msec.2020.111141DOI Listing
October 2020

Coupling characteristics and environmental significance of nitrogen, phosphorus and organic carbon in the sediments of Erhai Lake.

Environ Sci Pollut Res Int 2020 Jun 30;27(16):19901-19914. Epub 2020 Mar 30.

College of Agricultural Science, Hebei North University, Zhangjiakou, 075131, Hebei, China.

The contents and forms of nitrogen (N), phosphorus (P), and organic carbon (C) were determined with 40 cm (approximately 1600 s) core sediments from Erhai Lake on the Yungui Plateau of China as the sample. The vertical distribution characteristics, coupling relationships and ecological indicator significance of C-N-P were studied and identified. The results showed that the total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) contents were in the ranges of 1436-8255 mg·kg, 1287-5462 mg·kg, and 870.26-1507.74 mg·kg, respectively. In the Erhai Lake sediments, the main forms of TOC, organic nitrogen (ON) and organic phosphorus (OP) were humus, TN, and TP, respectively. The deposition of C, N, and P in the Erhai Lake sediments was divided into four periods. In the initial development period (from 40 to 23 cm), C, N and P were deposited and released synchronously; the main form of N was nontransferable total nitrogen (NTN), and that of P was inorganic phosphorus (IP). In the ecological recovery period (from 22 to 14 cm), C and N were deposited synchronously, and their deposition amounts were more than that of P. C, N and P were released synchronously. The main form of N was transferable total nitrogen (TTN), and that of P was IP. In the rapid economic growth period (from 13 to 0 cm), C, N, and P were deposited and released synchronously; the main form of N was NTN, and that of P was OP. In comparison to the other periods, this period was a period of higher active soil organic carbon (ASOC). In the integrated management period (surface sediment), C and N were deposited and released synchronously, and their deposition amounts were greater than that of P. The main form of N was NTN, that of P was OP, and the ASOC content was high. When exogenous inputs were the main sources of C, N, and P, the deposition forms of P and N were mainly OP and NTN, respectively, and those of IP and TTN were calcium-bound P (Ca-P) and ion-exchange form N (IEF-N), respectively. When endogenous inputs were the main sources of C, N and P, the deposition forms of P and N were mainly IP and TTN, respectively, and those of IP and TTN were Fe/Al-P and weak acid extractable form (WAEF-N), respectively. The content ratio of Ca-P and Fe/Al-P, as well as that of IEF-N and WAEF-N, could reflect the changes in the contribution of endogenous and exogenous sources to the Erhai Lake sediments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11356-020-08120-9DOI Listing
June 2020

Distribution character of localized iron microniche in lake sediment microzone revealed by chemical image.

Environ Sci Pollut Res Int 2019 Dec 7;26(35):35704-35716. Epub 2019 Nov 7.

National Engineering Laboratory for Lake Pollution Control and Ecological Restoration, Chinese Research Academy of Environmental Sciences (CRAES), Beijing, 100012, China.

DGT (diffusive gradients in thin films) technique and LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry) for heterogeneous distribution of the soluble labile iron (Fe) at submillimeter resolution in lake sediment porewater are reported. The soluble labile Fe species include ion and labile organic complexes. The chemical images in two dimensions (2D) for DGT concentration of Fe (C(Fe)) are investigated for Fe remobilization character. There are 902 C(Fe) values between 1000 and 2000 μg L, 463 values between 2000 and 3000 μg L, and 112 values over 3000 μg L in all chemical maps. Based on the linear correlation relationships between C (Fe) and total Fe (TFe), total organic carbon (TOC), acid-volatile sulfide (AVS), Eh, concentrations of the soluble reactive phosphorus (P) (SRP), and soluble labile trace metals (Zn, Cu, Pb, and Zn) in a vertical 1D profile of sediment or porewater, Fe release mechanisms are mainly due to the reductive Fe release from iron oxyhydroxides and the decomposition of organic matter in algae biomass and deep sediment layer. It can be used to explain the formation mechanisms of Fe microniches in chemical maps with heterogeneous character to a great extent. C(Fe) peak flux in the center of Fe microniche and the low C (Fe) at the edge of a microniche are due to the formation of the insoluble iron sulfide and the abundant acid-volatile sulfide (AVS) in sediment. The verified co-remobilization of the soluble labile Fe and trace metals or SRP in sediment porewater can be used to predict their simultaneous release from Fe microniches with the large C (Fe) peaks. The different kinds of Fe microniche zones and hot spots from sediment/water interface (SWI) to deep sediment correspond to the formation mechanisms of microniches mentioned above. Moreover, some narrow Fe microniche zones with the large C (Fe) across chemical maps are due to the desorption of Fe(II) from the freshly formed oxide on Myriophyllum verticiilatur roots, which are located at sites of microniche zones.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11356-019-06219-2DOI Listing
December 2019

Response of phosphorus fractionation in lake sediments to anthropogenic activities in China.

Sci Total Environ 2020 Jan 2;699:134242. Epub 2019 Sep 2.

Engineering Research Center of Ministry of Education on Groundwater Pollution Control and Remediation, College of Water Sciences, Beijing Normal University, Beijing 100875, China.

In this study, geochemical fractionation is used to establish the relationship between sediment phosphorus (P) pools and anthropogenic activities based on the dated sediment from a suite of lakes in China. Our extraction results showed that the inorganic P fractions, including Ca-P (46% of TP) and Fe/Al-P (24%), constitute most of the P in sediments. Soil erosion dynamics and geographic location are the dominant factors controlling the historical distribution and partitioning of Ca-P in sediments, while over the last few decades, industrial and domestic effluents were the leading factor controlling Fe/Al-P. The organic P (P) fractions, NaHCO-P, HCl-P, and Ful-P accounted for only 11%, 16% and 12% of P on average, respectively, whereas Hum-P and Res-P made up the dominant P fraction (59%) and were the main factors controlling P dynamics due to fertilizer and livestock breeding. Thus, the historical fraction of P in the sediment core can be used as an indicator of anthropogenic activities. Ca-P decreased in the top layers of the cores because of the implementation of the Soil and Water Conservation Law in China since 1991. However, Fe/Al-P and P continuously increased in the lakes from the economic backward area over the last few decades, which is largely due to enhanced point sources of pollution and an increase in the intensity of agricultural practices. As a potential P source, the massive accumulation of Fe/Al-P and P would be released into the overlying water to further facilitate eutrophication via increasing pH and alkaline phosphatase and decreasing in the dissolved oxygen concentration. Therefore, in order to control eutrophication more effectively and efficiently, it is essential that the accumulation of sediment Fe/Al-P and P be decreased immediately and domestic wastewater, poultry excreta, and fertilizer loss must be more carefully controlled, especially in economically backward areas.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2019.134242DOI Listing
January 2020

Synthesis and phosphate adsorption behaviour of Mg/Al-pillared montmorillonite loaded with La(OH).

Environ Technol 2021 Apr 20;42(11):1652-1668. Epub 2019 Oct 20.

College of Water Sciences, Beijing Normal University, Beijing, People's Republic of China.

Magnesium/aluminum-pillared montmorillonite loaded with lanthanum hydroxide (Mg/Al-MMT-La(OH)) was synthesized using non-toxic raw materials by ion-exchange and co-precipitation for phosphate removal from wastewater. Some adsorbents were fabricated in different molar ratios of Mg to Al, analyzed using various characterizations, and investigated in batch adsorption experiments. The determined adsorption kinetics of the 1:4 Mg/Al-MMT-La(OH) composite fitted well with the Elovich model. In addition, the Langmuir model revealed the high adsorption efficiency of phosphate by the adsorbent with a maximum adsorption capacity of 79.33 mg/g. The negative value of Δ° and positive value of Δ° (64.25 kJ/mol) demonstrated that phosphate adsorption onto 1:4 Mg/Al-MMT-La(OH) was spontaneous and endothermic in nature. Moreover, when the molar ratio of to was 1:5, the phosphate adsorption capacity reduced by 53.5%, far exceeding the effect of , , Cl, and . The addition of Al caused a sharp decline in phosphate removal property by 81.9% when /Al molar ratio was 1:5, however, the presence of other cations showed the negligible impact on it. The adsorption mechanism primarily involved ion exchange with intercalated anions and surface coordination with loaded hydroxides. Results proved that 1:4 Mg/Al-MMT-La(OH) material has a favourable application potential in the surface water remediation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/09593330.2019.1675775DOI Listing
April 2021

Phosphorus (P) release risk in lake sediment evaluated by DIFS model and sediment properties: A new sediment P release risk index (SPRRI).

Environ Pollut 2019 Dec 19;255(Pt 2):113279. Epub 2019 Sep 19.

National Engineering Laboratory for Lake Pollution Control and Ecological Restoration, Institute of Lake Environmental, Chinese Research Academy of Environmental Sciences (CRAES), Beijing 100012, China; College of Water Sciences, Beijing Normal University, Beijing, 100875, China.

A new sediment P release risk index (SPRRI) for "in-situ" phosphorus (P) release risk in lake sediment, is developed based on diffusive gradients in thin films (DGT) technique, DGT induced flux in sediments (DIFS) model and sediment properties. SPRRI includes three sub-indexes, which contain (1) the labile P pool size, (2) resupply constant (r) and desorption rate (Dspt rate) for P transfer and (3) the molar ratio between iron (Fe) in sequential extraction for sediment P by bicarbonate-dithionite (BD) and aluminum (Al) by NaOH (at 25 °C), i.e. BD(Fe)/Al[NaOH25] in sediment solid. The first sub-index considers P release from (i) sediment with NHCl-P+BD-P pool, i.e. the loosely sorbed P (NHCl-P) plus iron associated P (BD-P), or (ii) sediment with NHCl-P pool, respectively. The second and third sub-indexes reflect kinetic P desorption and resupply ability of solid phase, and the effect of P sequestration by Al hydroxide on P release, in turn. The inner relationship between SPRRI and sub-indexes, and their effects on P release risk are elucidated. SPRRI can be used to evaluate sediment P reactivity by five release risk ranks. For Lake Dianchi (China), P transfer dynamics, labile P pool, resupply ability and Al-P in sediment, and "external P-loading" control and affect P release risk in different regions, which is reflected by the spatial distribution map for SPRRI. The present SPRRI can be applied for lakes with (1) pH range varying from moderate acidity to weak alkalinity in waterbody and (2) NHCl-P or NHCl-P+BD-P pool in sediment solid.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.envpol.2019.113279DOI Listing
December 2019

The potential role of sediment organic phosphorus in algal growth in a low nutrient lake.

Environ Pollut 2019 Dec 11;255(Pt 2):113235. Epub 2019 Sep 11.

Centre for Ecology & Hydrology, Bush Estate, Penicuik, Midlothian, EH26 0QB, UK.

The role of sediment-bound organic phosphorus (P) as an additional nutrient source is a component of internal P budgets in lake system that is usually neglected. Here we examined the relative importance of sediment P to internal P load and the role of bioavailable P in algal growth in Lake Erhai, China. Lake Erhai sediment extractable P accounted for 11-43% (27% average) of extractable total P, and bioavailable P accounted for 21-66% (40%) of P. The massive storage of bioavailable P represents an important form of available P, essential to internal loads. The bioavailable P includes mainnly labile monoester P and diester P was identified in the sequential extractions by HO, NaHCO, NaOH, and HCl. 40% of HO-P, 39% of NaHCO-P, 43% of NaOH-P, and 56% of HCl-P can be hydrolyzed to labile monoester and diester P, suggesting that the bioavailability of P fractions was in decreasing order as follows: HCl-P > NaOH-P > HO-P > NaHCO-P. It is implied that traditional sequential fractionation of P might overestimate the availability of labile P in sediments. Furthermore, analysis of the environmental processes of bioavailable P showed that the stabler structure of dissloved organic matter (DOM) alleviated the degradation and release of diester P, abundant alkaline phosphatase due to higher algal biomass promoted the degradation of diester P. The stability of DOM structure and the degradation of diester P might responsible for the spatial differences of labile monoester P. The biogeochemical cycle of bioavailable P replenishs available P pools in overlying water and further facilitate algal growth during the algal blooms. Therefore, to control the algal blooms in Lake Erhai, an effective action is urgently required to reduce the accumulation of P in sediments and interrupt the supply cycle of bioavailable P to algal growth.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.envpol.2019.113235DOI Listing
December 2019

Feature-weighted survival learning machine for COPD failure prediction.

Artif Intell Med 2019 05 28;96:68-79. Epub 2019 Mar 28.

Département de Médecine de Famille et de Médecine d'Urgence, Université de Sherbrooke, Québec J1H 5N4, Canada; Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke (CRCHUS), Québec J1H 5N4, Canada. Electronic address:

Chronic obstructive pulmonary disease (COPD) yields a high rate of failures such as hospital readmission and death in the United States, Canada and worldwide. COPD failure imposes a significant social and economic burden on society, and predicting such failure is crucial to early intervention and decision-making, making this a very important research issue. Current analysis methods address all risk factors in medical records indiscriminately and therefore generally suffer from ineffectiveness in real applications, mainly because many of these factors relate weakly to prediction. Numerous studies have been done on selecting factors for survival analysis, but their inherent shortcomings render these methods inapplicable for failure prediction in the context of unknown and intricate correlation patterns among risk factors. These difficulties have prompted us to design a new Cox-based learning machine that embeds the feature weighting technique into failure prediction. In order to improve predictive accuracy, we propose two weighting criteria to maximize the area under the ROC curve (AUC) and the concordance index (C-index), respectively. At the same time, we perform a Dirichlet-based regularization on weights, making differences between factor relevance clearly visible while maintaining the model's high predictive ability. The experimental results on real-life COPD data collected from patients hospitalized at the Centre Hospitalier Universitaire de Sherbrooke (CHUS) demonstrate the effectiveness of our learning machine and its great promise in clinical applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.artmed.2019.01.003DOI Listing
May 2019

Response of sediment organic phosphorus composition to lake trophic status in China.

Sci Total Environ 2019 Feb 17;652:495-504. Epub 2018 Oct 17.

Lancaster Environment Centre, Library Avenue, Lancaster University, Lancaster LA14YQ, UK; Centre & Centre for Ecology and Hydrology Benson Lane, Wallingford, Oxfordshire OX108BB, UK.

Organic phosphorus (P) constitutes the most important fraction of P in lake sediments, and the compositional properties of P affect its behavior in lake ecosystems. In this study, P NMR, FT-IR spectroscopy, and UV-visible absorbance spectroscopy were combined to identify the dynamic composition of sediment P across two sets of lakes in China ranging from oligotrophic to eutrophic, and their possible effects on lake eutrophication were evaluated. The results showed that sediment P content (accounting for 24-75% of TP) was positively correlated with trophic status in both Eastern Plain and Yun-Gui Plateau lakes of China, and the linear relationship was more stable compared to total P (TP), implying that sediment P may be a superior indicator of trophic status than TP. The P component, phosphonate accounted for only 0.4% or less of P, while the monoester P and diester P, accounted for 2-24% and 0.5-5% of P, respectively, and were the main factors causing P to increase with the increasing trophic status. The factors were closely related to the enhanced organic sewage load and intensification of contemporary sedimentation of phytoplankton. As trophic status increased, sediment P might integrate into larger amounts of aromatic substances and functional groups, which could enhance the stability of P in sediments. Furthermore, sediments from lakes with higher trophic status exhibited a higher degree of humification and molecular weights, which impart resistance to biodegradation, and therefore, reduced the risk of sediment P release. However, the massive accumulation of bioavailable P (monoester and diester P) allows possible degradation, supporting algal growth and maintains eutrophic status because there is abundant alkaline phosphatase in eutrophic lakes. Thus, to control lake eutrophication more effectively, targeted actions are urgently required to reduce the accumulation and degradation of P in lake sediment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2018.10.233DOI Listing
February 2019

In-depth molecular characterization and biodegradability of water-extractable organic nitrogen in Erhai Lake sediment.

Environ Sci Pollut Res Int 2018 Jul 8;25(20):19779-19789. Epub 2018 May 8.

Engineering Research Center of Beijing, Beijing University of Technology, Beijing, 100022, China.

Dissolved organic nitrogen (DON) constitutes a significant fraction of the total dissolved nitrogen content of most aquatic systems and is thus a major nitrogen source for bacteria and phytoplankton. The present work applied Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to a compound-level analysis of the depth-dependent molecular composition of water-extractable organic nitrogen (WEON) in lake sediment. The study focused on Erhai Lake, China. It was found that a large portion (from 16.33 ± 7.87 to 39.54 ± 5.77%) of the WEON in the lake sediment was reactive under cultivation by algal or bacteria. The WEON in the mid-region of Erhai sediment particularly exhibited a lower bioavailability, having been less affected by the basin environment. The FT-ICR MS results revealed the presence of thousands of compounds in the Erhai Lake sediment samples collected at different depths, with the N-containing compounds accounting for 28.3-34.4% of all the compounds. The WEON molecular weight was also observed to increase with increasing sediment depth. A van Krevelen diagram showed that the lignin-type components were dominant (~ 56.2%) in the sediment WEON, contributing to its stabilization and reducing the risk of sediment nutrient release. The FT-ICR MS results further revealed 204 overlapping formulas of WEON for each core sediment sample, attributable to the presence of refractory components. It was observed that 78.4% of the formulas were within the lignin-like region, suggesting unique allochthonous DON sources. The aliphatic component proportion of all the unique formulas was also found to increase with increasing sediment depth. This indicates that, with the development and evolution of the Erhai Basin, the more labile WEON components were transformed into more stable lignin-like substrates, with a positive effect on the Lake Erhai ecosystem. Graphical abstract ᅟ.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11356-018-2122-zDOI Listing
July 2018

Optimum water depth ranges of dominant submersed macrophytes in a natural freshwater lake.

PLoS One 2018 7;13(3):e0193176. Epub 2018 Mar 7.

State Key Laboratory of Environmental Criteria and Risk Assessment, State Environmental Protection Key Laboratory for Lake Pollution Control, Research Center for Lake Ecology and Environments, Chinese Research Academy of Environmental Sciences (CRAES), Beijing, China.

Macrophytes show a zonal distribution along the lake littoral zone because of their specific preferred water depths while the optimum growth water depths of dominant submersed macrophytes in natural lakes are not well known. We studied the seasonal biomass and frequency patterns of dominant and companion submersed macrophytes along the water depth gradient in Lake Erhai in 2013. The results showed that the species richness and community biomass showed hump-back shaped patterns along the water depth gradient both in polydominant and monodominant communities. Biomass percentage of Potamogenton maackianus showed a hump-back pattern while biomass percentages of Ceratophyllum demersum and Vallisneria natans appeared U-shaped patterns across the water depth gradient in polydominant communities whereas biomass percentage of V. natans increased with the water depth in monodominant communities. Dominant species demonstrated a broader distribution range of water depth than companion species. Frequency and biomass of companion species declined drastically with the water depth whereas those of dominant species showed non-linear patterns across the water depth gradient. Namely, along the water depth gradient, biomass of P. maackianus and V. natans showed hump-back patterns and biomasses of C. demersum displayed a U-shaped pattern in the polydominant communities but biomass of V. natans demonstrated a hump-back pattern in the monodominant communities; frequency of P. maackianus showed a hump-back pattern and C. demersum and V. natans maintained high frequencies in the two types of communities. We can speculate that in Lake Erhai the optimum growth water depths of P. maackianus and C. demersum in the polydominant communities are 2.5-4.5 m and 1-2 m or 5-6 m, respectively and that of V. natans is 3-5 m in the polydominant communities and 2.5-5 m in the monodominant communities. This is the first report that the optimum water depth ranges in the horizontal direction of three dominant submersed macrophytes in a natural freshwater lake were determined.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0193176PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5841742PMC
June 2018

Transfer kinetics of phosphorus (P) in macrophyte rhizosphere and phytoremoval performance for lake sediments using DGT technique.

J Hazard Mater 2018 05 7;350:189-200. Epub 2018 Feb 7.

State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, China.

DGT (diffusive gradients in thin films) technique and DIFS (DGT induced fluxes in sediment) model are firstly designed for macrophyte-rhizobox system and in-situ macrophytes in Lake Erhai. Dynamics of phosphorus (P) transfer in Zizania latifolia (ZL) and Myriophyllum verticiilatur (MV) rhizosphere is revealed and phytoremediation performance for P in sediment is evaluated. Dynamic transfer process of P at DGT/sediment interface includes (i) diffusion flux and concentration gradients at DGT(root)/porewater interface leading to porewater concentration (C) depletion and (ii) P desorption from labile P pool in sediment solid to resupply C depletion. Fe-redox controlled P release from Fe-bound P (BD-P2) and then NHCl-P1 in rhizosphere sediment resupplies porewater depletion due to DGT (root) sink. K (labile P pool size in solid phase), r (resupply ratio) and kinetic exchange (Tc and k) lead to change characters of DIFS curves of (1) r against deployment time and (2) C (dissolved concentration) against distance at 24 h. They include two opposite types of "fast" and "slow" rate of resupplies. Sediment properties and DIFS parameters control P diffusion and resupply in rhizosphere sediment. Phytoremoval ability for sediment P in lake is estimated to be 23.4 (ZL) or 15.0 t a (MV) by "DGT-flux" method.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jhazmat.2018.02.005DOI Listing
May 2018

Transfer Mechanism, Uptake Kinetic Process, and Bioavailability of P, Cu, Cd, Pb, and Zn in Macrophyte Rhizosphere Using Diffusive Gradients in Thin Films.

Environ Sci Technol 2018 02 11;52(3):1096-1108. Epub 2018 Jan 11.

State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing, Jiangsu 210023, PR China.

The transfer-uptake-bioavailability of phosphorus (P), Cu, Cd, Zn, and Pb in rhizosphere of Zizania latifolia (ZL) and Myriophyllum verticiilaturn (MV) cultivated in rhizoboxes in Lake Erhai (China) is evaluated by DGT (diffusive gradients in thin films) technique. DGT induced fluxes in sediments (DIFS) model reveals that resupply ability (r), liable pool size in sediment solid (k), kinetic parameter (k), or response time (T) control the diffusion-resupply characters of P and Cu (standing for four metals) in rhizosphere interface. The linear fitting curves of element content in ZL or MV roots (C) against DGT (C), porewater (C), or sediment concentration demonstrate that C for five elements can be predicted by C more effectively than the other methods. (I) DOC (dissolved organic carbon) in porewater controlled by OM (organic matter) in solid plus pH for Cu and Cd or (II) DOP/DTP ratio in porewater (between dissolved organic P and dissolved total P) for P controlled by Fe-bound P and OM in solid, can affect phytoavailability in rhizosphere. They lead to (I) the larger slope (s) and the linear regression coefficient (R) in the first part than those for the complete fitting curve (ZL or MV root against C(Cu) or C(Cu) and MV root against C(Cd)) or (II) the outliers above or below the fitting curve (ZL root (P) against C(P) or C(P)) and the larger R without outliers. DGT-rhizobox-DIFS should be a reliable tool to research phytoremediation mechanism of macrophytes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.est.7b01578DOI Listing
February 2018

Features and influencing factors of nitrogen and phosphorus diffusive fluxes at the sediment-water interface of Erhai Lake.

Environ Sci Pollut Res Int 2018 Jan 4;25(2):1933-1942. Epub 2017 Nov 4.

National Engineering Laboratory for lake water pollution control and ecological restoration technology, State Environmental Protection Key Laboratory for Lake Pollution Control, Research Center of Lake Eco-environment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.

Nitrogen and phosphorus diffusion at the sediment-water interface is vital to the water quality of lakes. In this paper, N and P diffusive fluxes at the sediment-water interface in Erhai Lake were studied using the sediment-pore water diffusive flux method. Characteristics of temporal and spatial variation of N and P diffusive fluxes were analyzed. Effects of the physicochemical properties of sediments and overlying water were discussed. Results showed that (1) the total N and P diffusive fluxes at the sediment-water interface of Erhai Lake are relatively low. The diffusive flux of ammonia nitrogen is 8.97~74.84 mgd m, higher in the middle of the lake, followed by the northern and southern regions successively. The P diffusive flux is -0.007~0.050 mgd m, higher in northern region of the lake, followed by middle and southern regions successively. The annual N diffusive flux has two peaks, and the higher peak is in September. The annual P diffusive flux shows a "V-shaped" variation, reaching the valley in July. N and P diffusive fluxes decrease with an increase of sediment depth. Overall, N and P diffusive fluxes at the sediment-water interface in Erhai Lake show different temporal and spatial variation. (2) Aquatic plants promote N and P diffusion at the sediment-water interface in Erhai Lake. The pH, DO, and SD of the overlying water are important influencing factors for the P diffusive flux. P diffusive flux is inversely proportional to the total phosphorous (TP) concentration of the overlying water. The physicochemical environment of overlying water slightly influences the N diffusive flux. The activity of sediments and the organic content are two main influencing factors of N diffusive flux, while P content and morphology of sediments are the main influencing factors of P diffusive flux. Iron and manganese ions are important elements that influence N and P diffusive fluxes at the sediment-water interface. (3) The P diffusive flux at the sediment-water interface in Erhai Lake is mainly affected by the physical and chemical properties of water, whereas the N diffusive flux is mainly influenced by the mineralization of organic matter in sediments. The P diffusive flux at the sediment-water interface is sensitive to the overlying water quality. Sediment transformation from "source" to "sink" was observed in 1 year. On the contrary, N diffusive flux is less sensitive to lake water quality. Endogenetic pollutant control in Erhai Lake should focus on P control.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11356-017-0556-3DOI Listing
January 2018

Characteristics and effects of dissolved organic phosphorus from different sources on the water quality of Erhai Lake in Southwest China.

Environ Sci Pollut Res Int 2017 Aug 24;24(22):18605-18618. Epub 2017 Jun 24.

State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.

To establish the influence of dissolved organic phosphorus (DOP) from different sources on the water quality of Erhai Lake in August 2014, enzymatic hydrolysis technology was used to characterize enzymatically hydrolyzable phosphorus (EHP). The results indicate that the DOP represents a significant source of the bioavailable P in the lake water and its different sources of Erhai Lake, and the bioavailability of the P pool may be underestimated by up to 55% if DOP is ignored and only the soluble-reactive phosphorus (SRP) is considered. The significant differences in DOP characteristics from the different sources may be related to the origin of the DOP, regional pollution, and environmental factors. The DOP from the sediment porewater can act as an important source of DOP in the lake water based on its high DOP content and high DOP loads from the sediment release. In addition, the highest EHP loads from the sediment release can threaten the water quality of Erhai Lake and sustain the algal blooms when they occur. Therefore, for the protection of Erhai Lake, the contributions of not only the SRP but also the DOP to the bioavailable P pool should be considered, emphasizing the eutrophication risk caused by DOP from sediments, especially in the middle section of Erhai Lake. The effects of DOP from the inflowing rivers on the water quality should also not be ignored, due to its high bioavailability.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11356-017-9474-7DOI Listing
August 2017

Characteristics of dissolved organic phosphorus inputs to freshwater lakes: A case study of Lake Erhai, southwest China.

Sci Total Environ 2017 Dec 9;601-602:1544-1555. Epub 2017 Jun 9.

State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; Yunnan Key Laboratory of Pollution Process and Management of Plateau Lake-Watershed, Kunming 650034, Yunnan Province, China.

In this study, we made the first estimate of the annual dissolved organic phosphorus (DOP) load to Lake Erhai, a typical mesotrophic-eutrophic lake in China. We also evaluated what proportion of DOP was bioavailable using enzymatically hydrolyzable phosphorus (EHP), and further assessed the potential impacts of DOP on lake water quality. We estimated that the annual DOP load into Lake Erhai accounted for nearly 50% of total dissolved phosphorus, while EHP accounted for about 30% of the bioavailable phosphorus (BAP) pool. The DOP load increased and accounted for a greater proportion of total dissolved phosphorus and BAP loads during the wet season, and helped maintain algal blooms. Inflowing rivers were the main source of DOP with high bioavailability to Lake Erhai, especially in the wet season. The EHP concentrations of the inflowing rivers were positively correlated with algal biomass. The observation suggests that, as a significant source of BAP, the contribution of the DOP load to eutrophication of the lake should not be ignored, especially given the low soluble reactive phosphorus concentrations in the lake water during the algal biomass period. Information on the contributions from different pollution sources is needed to support the development of effective P pollution control strategies. Short-term strategies to protect Lake Erhai include better management of the inflowing rivers, especially in the northern part during the wet season, while, over the long-term, strategies to decrease P release from lake sediments should be considered.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2017.05.265DOI Listing
December 2017

Structurexplor: a platform for the exploration of structural features of RNA secondary structures.

Bioinformatics 2017 Oct;33(19):3117-3120

Department of Computer Science, Faculty of Science, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1 Canada.

Summary: Discovering function-related structural features, such as the cloverleaf shape of transfer RNA secondary structures, is essential to understand RNA function. With this aim, we have developed a platform, named Structurexplor, to facilitate the exploration of structural features in populations of RNA secondary structures. It has been designed and developed to help biologists interactively search for, evaluate and select interesting structural features that can potentially explain RNA functions.

Availability And Implementation: Structurxplor is a web application available at http://structurexplor.dinf.usherbrooke.ca. The source code can be found at http://jpsglouzon.github.io/structurexplor/.

Contact: [email protected]

Supplementary Information: Supplementary data are available at Bioinformatics online.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/bioinformatics/btx323DOI Listing
October 2017

New insights into the source of decadal increase in chemical oxygen demand associated with dissolved organic carbon in Dianchi Lake.

Sci Total Environ 2017 Dec 30;603-604:699-708. Epub 2017 Mar 30.

State Key Laboratory of Environmental Criteria and Risk Assessment, State Environmental Protection Key Laboratory for Lake Pollution Control, Research Center of Lake Eco-environment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; Yunnan Key Laboratory of Pollution Process and Management of Plateau Lake Watershed, Kunming, Yunnan Province, 650034, China.. Electronic address:

Dissolved organic carbon (DOC) can be used an alternative index of water quality instead of chemical oxygen demand (COD) to reflect the organic pollution in water. The monitoring data of water quality in a long-term (1990-2013) from Dianchi Lake confirmed the increase trend of COD concentration in the lake since 2007. The similarities and differences in the DOC components between the lake and its sources and the contribution from allochthonous and autochthonous DOC to the total DOC in this lake were determined to elucidate the reason of COD increase based on C/N atomic ratios, stable isotope abundance of carbon and nitrogen, UV-visible spectroscopy, three-dimensional excitation-emission matrix (3DEEM) fluorescence spectroscopy. The terrigenous organic matter showed humic-like fluorescence, and the autochthonous organic matter showed tryptophan-like components. Agricultural runoff (9.5%), leaf litter (7.5%) and urban runoff (13.2%) were the main sources of DOC in the lake. Sewage tail was a major source of organic materials, 3DEEM for the indicates that sewage tail DOC composition did not change markedly over the biodegradation period, indicating that sewage tail contains a high load of DOC that is resistant to further biodegradation and subsequently accumulates in the lake. The change of land use in the catchment and the increase of sewage tail load into the lake are the key factors for the increase in COD concentration in Dianchi Lake. Thus, the lake should be protected by controlling the pollution from the urban nonpoint sources and refractory composition in point sources.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.scitotenv.2017.02.024DOI Listing
December 2017

Release mechanism and kinetic exchange for phosphorus (P) in lake sediment characterized by diffusive gradients in thin films (DGT).

J Hazard Mater 2017 Jun 21;331:36-44. Epub 2017 Feb 21.

State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, PR China; State Environmental Protection Key Laboratory for Lake Pollution Control, Research Center of Lake Eco-Environment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, PR China; Dongtinghu Lake Ecological Observation and Research Station (DEORS), Yueyang, Hunan Province, 41400, PR China; Yunnan Key Laboratory of Pollution Process and Management of Plateau Lake-Watershed, Kunming, Yunnan Province, 650034, PR China. Electronic address:

Diffusive gradients in thin films (DGT) technique has been newly designed for the identification of formation mechanisms of "internal phosphorus (P)-loading" and the numerical simulation of P exchange at DGT/sediment interface in Lake Dianchi. The primary mechanism was Fe-redox controlled P release from Fe-bound P in sediments, which was revealed by C (P and Fe), total P (Fe) and P (Fe) fractions in NHCl and BD phases in sediments and their relationships at sites (N-T). The breakdown of algae biomass in the top layer of sediments at sites (O-T) and the coupled P/Fe/sulfur reactions at two depths at site N played a minor role in P release. The "internal P-loading" was calculated to be 19.23ta, which was 3.0% of the "entering P-loading". At sites (1-9), DGT induced flux in sediments (DIFS) model for P was used to derive curves (i) the resupply parameter (R) against deployment time and (ii) the dissolved/sorbed concentrations against the distance at DGT/sediment interface, the variation characters of which were controlled by kinetics and sediment-P pool. Sulfide microniches in sediments related to P release were evaluated by computer imaging densitometry (CID). DGT-DIFS-CID should be a reliable method to reveal P mobilization in lake sediments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jhazmat.2017.02.024DOI Listing
June 2017

Accuracy and generalizability of using automated methods for identifying adverse events from electronic health record data: a validation study protocol.

BMC Health Serv Res 2017 02 16;17(1):147. Epub 2017 Feb 16.

Department of Quality, Patient Safety and Performance, McGill University Health Centre, 2155 Guy Street, Montreal, QC, H3H 2R9, Canada.

Background: Adverse events (AEs) in acute care hospitals are frequent and associated with significant morbidity, mortality, and costs. Measuring AEs is necessary for quality improvement and benchmarking purposes, but current detection methods lack in accuracy, efficiency, and generalizability. The growing availability of electronic health records (EHR) and the development of natural language processing techniques for encoding narrative data offer an opportunity to develop potentially better methods. The purpose of this study is to determine the accuracy and generalizability of using automated methods for detecting three high-incidence and high-impact AEs from EHR data: a) hospital-acquired pneumonia, b) ventilator-associated event and, c) central line-associated bloodstream infection.

Methods: This validation study will be conducted among medical, surgical and ICU patients admitted between 2013 and 2016 to the Centre hospitalier universitaire de Sherbrooke (CHUS) and the McGill University Health Centre (MUHC), which has both French and English sites. A random 60% sample of CHUS patients will be used for model development purposes (cohort 1, development set). Using a random sample of these patients, a reference standard assessment of their medical chart will be performed. Multivariate logistic regression and the area under the curve (AUC) will be employed to iteratively develop and optimize three automated AE detection models (i.e., one per AE of interest) using EHR data from the CHUS. These models will then be validated on a random sample of the remaining 40% of CHUS patients (cohort 1, internal validation set) using chart review to assess accuracy. The most accurate models developed and validated at the CHUS will then be applied to EHR data from a random sample of patients admitted to the MUHC French site (cohort 2) and English site (cohort 3)-a critical requirement given the use of narrative data -, and accuracy will be assessed using chart review. Generalizability will be determined by comparing AUCs from cohorts 2 and 3 to those from cohort 1.

Discussion: This study will likely produce more accurate and efficient measures of AEs. These measures could be used to assess the incidence rates of AEs, evaluate the success of preventive interventions, or benchmark performance across hospitals.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12913-017-2069-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5314632PMC
February 2017

The super-n-motifs model: a novel alignment-free approach for representing and comparing RNA secondary structures.

Bioinformatics 2017 Apr;33(8):1169-1178

Department of Computer Science, Faculty of Science, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada.

Motivation: Comparing ribonucleic acid (RNA) secondary structures of arbitrary size uncovers structural patterns that can provide a better understanding of RNA functions. However, performing fast and accurate secondary structure comparisons is challenging when we take into account the RNA configuration (i.e. linear or circular), the presence of pseudoknot and G-quadruplex (G4) motifs and the increasing number of secondary structures generated by high-throughput probing techniques. To address this challenge, we propose the super-n-motifs model based on a latent analysis of enhanced motifs comprising not only basic motifs but also adjacency relations. The super-n-motifs model computes a vector representation of secondary structures as linear combinations of these motifs.

Results: We demonstrate the accuracy of our model for comparison of secondary structures from linear and circular RNA while also considering pseudoknot and G4 motifs. We show that the super-n-motifs representation effectively captures the most important structural features of secondary structures, as compared to other representations such as ordered tree, arc-annotated and string representations. Finally, we demonstrate the time efficiency of our model, which is alignment free and capable of performing large-scale comparisons of 10 000 secondary structures with an efficiency up to 4 orders of magnitude faster than existing approaches.

Availability And Implementation: The super-n-motifs model was implemented in C ++. Source code and Linux binary are freely available at http://jpsglouzon.github.io/supernmotifs/ .

Contact: [email protected]

Supplementary Information: Supplementary data are available at Bioinformatics o nline.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/bioinformatics/btw773DOI Listing
April 2017

A new method for decontamination of de novo transcriptomes using a hierarchical clustering algorithm.

Bioinformatics 2017 05;33(9):1293-1300

Agriculture and Agri-Food Canada, Saint-Jean-sur-Richelieu, QC J3B 3E6, Canada.

Motivation: The identification of contaminating sequences in a de novo assembly is challenging because of the absence of information on the target species. For sample types where the target organism is impossible to isolate from its matrix, such as endoparasites, endosymbionts and soil-harvested samples, contamination is unavoidable. A few post-assembly decontamination methods are currently available but are based only on alignments to databases, which can lead to poor decontamination.

Results: We present a new decontamination method based on a hierarchical clustering algorithm called MCSC. This method uses frequent patterns found in sequences to create clusters. These clusters are then linked to the target species or tagged as contaminants using classic alignment tools. The main advantage of this decontamination method is that it allows sequences to be tagged correctly even if they are unknown or misaligned to a database.

Availability And Implementation: Scripts and documentation about the MCSC decontamination method are available at https://github.com/Lafond-LapalmeJ/MCSC_Decontamination .

Contact: : [email protected]

Supplementary Information: Supplementary data are available at Bioinformatics online.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/bioinformatics/btw793DOI Listing
May 2017

Molecular characterization of lake sediment WEON by Fourier transform ion cyclotron resonance mass spectrometry and its environmental implications.

Water Res 2016 Dec 28;106:196-203. Epub 2016 Sep 28.

State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; State Environmental Protection Key Laboratory for Lake Pollution Control, Research Center of Lake Eco-environment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.

The compositional properties of water-extractable organic nitrogen (WEON) affect its behavior in lake ecosystems. This work is the first comprehensive study using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) for the characterization of the molecular composition of WEON in lake sediment. In sediments of Erhai Lake in China, this study found complex WEON species, with N-containing compounds in the northern, central, and southern regions contributing 34.47%, 42.44%, and 40.6%, respectively, of total compounds. Additionally, a van Krevelen diagram revealed that lignin components were dominant in sediment WEON structures (68% of the total), suggesting terrestrial sources. Furthermore, this study applied ESI-FT-ICR-MS to the examination of the environmental processes of lake sediment WEON on a molecular level. The results indicated that sediment depth impacted WEON composition and geochemical processes. Compared with other ecosystems, the double bond equivalent (DBE) value was apparently lower in Erhai sediment, indicating the presence of relatively fewer and smaller aromatic compounds. In addition, the presence of a large number of N-containing species and abundant oxidized nitrogen functional compounds that were likely to biodegrade may have further increased the potential releasing risk of WEON from Erhai sediment under certain environmental conditions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.watres.2016.09.059DOI Listing
December 2016
-->