Machine learning-based prediction of methane production from lignocellulosic wastes.

The biochemical methane potential test is a standard method to determine the biodegradability of lignocellulosic wastes (LWs) during anaerobic digestion (AD) with disadvantages of long experiment duration and high operating expense. This paper developed a machine learning model to predict the cumulative methane yield (CMY) using the data of 157 LWs regarding physicochemical characteristics, digestion condition and methane yield, with the coefficient of determination equal to 0.869. Model interpretability analyses underscored lignin content, organic loading, and nitrogen content as pivotal attributes for CMY prediction. For the feedstocks with a cellulose content exceeding about 50%, the CMY in the early AD stage would be relatively lower than those with low cellulose content, but prolonging digestion time could promote methane production. Besides, lignin content in feedstock surpassing 15% would significantly inhibit methane production. This work contributes to valuable guidance for feedstock selection and operation optimization for AD plants.

Enhancing acidification efficiency of vegetable wastes through heat shock pretreatment and initial pH regulation.

Anaerobic digestion (AD) technology is a practical approach to alleviate severe environmental issues caused by vegetable wastes (VWs). However, its primary product is methane-rich biogas converted from the precursors (mainly volatile fatty acids, VFAs) after long fermentation periods, making traditional AD projects of low economic profits. Intervening in the methanogenesis stage artificially to produce high value-added VFAs can shorten the reaction time of the AD process and significantly improve profits, posing a promising alternative for treating VWs. Given this, this study applied heat shock (HS) pretreatment to inoculum to prevent methane production during AD and systemically investigated the effects of HS pretreatment and initial pH regulation on VFA production from VWs. The results showed that appropriate HS pretreatment effectively inhibited methane generation but promoted VFA accumulation, and VFA production was further enhanced by adjusting the initial pH to 8.0 and 9.0. The highest total VFA concentration of 14,883 mg/L with a VFA yield of 496.1 mg/gVS, 26.98% higher than that of the untreated group, was achieved at an initial pH 8.0 with HS pretreatment of 80 °C for 1 h. Moreover, pH regulation influenced the metabolic pathway of VFA production from VWs during AD, as butyrate was the dominant product at an initial pH of 6.0, while the increased initial pH improved the acetate proportion.

Performance and mechanism of various microaerobic pretreatments on anaerobic digestion of tobacco straw.

Tobacco straw is an abundant biomass in China's agricultural ecosystems, and has high potential for methane production. However, the anaerobic digestion (AD) efficiency is limited by the recalcitrant lignocellulose structure of the tobacco straw. In this study, three microaerobic pretreatments were performed for the AD of tobacco straw to increase methane production. Among them, microbial pretreatment with biogas slurry at an oxygen concentration of 4 mL/g VS resulted in the highest methane production of 349.1 mL/g VS, increasing by 19.8 % than that of untreated. During this pretreatment, the relative abundances of Enterococcus and Clostridium sensu stricto 12, which are closely related to acetic acid production and cellulose degradation, were high, and these bacteria might have an important contribution to substrate hydrolysis and the methanogenesis efficiency of the AD process. This study advances the understanding of microaerobic pretreatment processes and provides technological guidance for the efficient utilization of tobacco straw.

Neural correlates of central pain sensitization in chronic low back pain: a resting-state fMRI study.

PURPOSE: The objective of this study is to explore the neural correlates of pain sensitization in patients with chronic low back pain (cLBP). While the association between cLBP and pain sensitization has been widely reported, the underlying brain mechanism responsible for this relationship requires further investigation. METHODS: Our study included 56 cLBP patients and 56 healthy controls (HC). Functional magnetic resonance imaging data were obtained, and the voxel-wise amplitude of low-frequency fluctuation (ALFF) was calculated to identify brain alterations in cLBP patients compared to HC groups. Pearson correlation coefficients were computed to explore the association between clinical data and brain alterations. Furthermore, mediation analyses were performed to investigate the path association between brain alterations and pain-related behaviors. RESULTS: Our findings revealed that patients with cLBP exhibited higher sensitivity, attention, and catastrophizing tendencies towards pain compared to HC. Furthermore, cLBP patients displayed significantly higher ALFF in various brain regions within the "pain matrix" and the default mode network when compared to HC. The altered precuneus ALFF was positively correlated with pain intensity (R = 0.51, P<0.001) and was negatively correlated with pain sensitivity (R = -0.43, P<0.001) in cLBP patients. Importantly, the effect of altered precuneus ALFF on pain intensity was mediated by pain threshold in these patients. CONCLUSION: Our study suggests that altered neural activity in the precuneus may contribute to pain hypersensitivity, which further exacerbating pain in cLBP patients.

Changes in the IL-18, IL-22, and T lymphocyte subset levels in patients with hepatitis B-related liver cirrhosis and their predictive values for hepatorenal syndrome.

OBJECTIVE: To investigate the changes in the interleukin (IL)-18, IL-22, and T lymphocyte subset levels in patients with hepatitis B-related liver cirrhosis and to determine their predictive values for hepatorenal syndrome (HRS). METHODS: Clinical data of 70 healthy individuals (group A) and 84 patients with hepatitis B-related liver cirrhosis (group B) admitted to Hospital 989 of the PLA Joint Logistics Support Force were retrospectively collected. The serum levels of IL-18 and IL-22, concentrations of cluster of differentiation (CD)3+, CD4+, and CD8+ cells, as well as the CD4+/CD8+ ratio in the peripheral blood T lymphocyte subsets were measured. Further, their predictive values for HRS were determined. Logistic regression analysis was employed to identify independent risk factors for HRS. RESULTS: In group B, the posttreatment IL-18 and IL-22 levels and CD8+ cell concentration significantly decreased after treatment, whereas the CD3+ and CD4+ cell concentrations and CD4+/CD8+ ratio increased. Notably, the serum IL-18 and IL-22 levels were higher in patients with HRS than in those without. Also, the CD3+ and CD4+ cell concentrations and CD4+/CD8+ ratio in the peripheral blood were lower in patients with HRS than in those without. The sensitivities of the serum IL-18 and IL-22 levels for predicting HRS were 90.32% and 80.65%, and the specificities were 71.70% and 77.36%, respectively. The sensitivities of CD3+, CD4+, and CD8+ cell concentrations for predicting HRS were 77.42%, 90.32%, and 83.87%, and the specificity was 67.92%, 64.15%, and 52.83%, respectively. Moreover, the sensitivity and specificity of CD4+/CD8+ ratio for predicting HRS were 80.65% and 86.79%, respectively. CONCLUSIONS: IL-18, IL-22, and T lymphocyte subset levels may have significant implications in the progression of hepatitis B-related liver cirrhosis, and detecting these markers could aid in treatment, evaluation, and prediction of HRS in patients. Furthermore, IL-18 and IL-22 levels and the CD4+/CD8+ ratio were identified as independent risk factors for HRS.

Responses of soil phosphorus cycling and bioavailability to plant invasion in river-lake ecotones.

The invasion of exotic plants in the river-lake ecotone has seriously affected the nutrient cycling processes in wetland soil. The South American species Alternanthera philoxeroides (Mart.) Griseb. is rapidly invading the river-lake ecotone in subtropical China, and has become the dominant species in the river-lake ecotone. However, there have been few studies on the effects of A. philoxeroides invasion on soil phosphorus (P) cycling and bioavailability in this ecotone. Here, we measured the bioavailable P fractions, physicochemical properties and nutrient content in the surface soils of the native plant (Zizania latifolia (Griseb.) Turcz and Nelumbo nucifera Gaertn.) communities and the adjacent invasive A. philoxeroides communities in three river-lake ecotones with different nutrient substrates in the subtropical Dongting Lake basin over a 3-year period to reveal the effects of A. philoxeroides invasion on the morphology and concentrations of soil bioavailable P. The principal coordinate analysis results showed that the A. philoxeroides invasion significantly altered the bioavailable P concentrations in the soil of native plant communities in the different river-lake ecotones, and this effect was not disturbed by the heterogeneity of the soil matrix. However, the effects of invasion into different native plant communities on the fractions of soil bioavailable P were different. Compared with native Z. latifolia and N. nucifera communities, A. philoxeroides invasion increased the concentration of inorganic P by 39.5% and 3.7%, respectively, and the concentration of organic P decreased by 32.7% and 31.9%, respectively. In addition, the invasion promoted P cycling and accumulation in the river-lake ecotone, which resulted in average decreases in the soil N:P and C:P ratios of 7.9% and 12.5%, respectively. These results highlight the impact of exotic plant invasions on nutrient cycling in wetland ecosystems in the river-lake ecotone, and this process may be detrimental to the late recovery of native plants.

Imaging parameters and clinical significance of posterior ligament complex injury in thoracolumbar fracture.

This study aims to investigate whether the combination of radiographs and computed tomography (CT) images can be used as an alternative means of magnetic resonance imaging examination or a preliminary screening method before examination, so as to improve the accuracy of determining the degree of posterior ligament complex injury in thoracolumbar fracture patients. From May 2011 to May 2019, the patients with thoracolumbar fracture were collected. A total of 150 patients were enrolled. The reference standard was 1.5T magnetic resonance imaging examination and lipid suppression sequence was applied. All radiographs and CT imaging results were measured in the Picture Archiving and Communication System workstation. The upper endplate angle and lower endplate angle, the percentage of vertebral height drop, the difference of inter-spinous process distance on CT images and the translation distance were statistically significant between the 2 groups (P < .05). Receiver operating characteristic curve showed that the diagnostic performance was excellent (all area under the curve > 0.7). To sum, the results showed that endplate angle + inter-spinous process distance on CT images combination had relatively high-quality diagnostic value for posterior ligamentous complex injury in thoracolumbar fracture patients.

In situ remediation mechanism of internal nitrogen and phosphorus regeneration and release in shallow eutrophic lakes by combining multiple remediation techniques.

Large anthropogenic inputs of N and P alter the nutrient cycle and exacerbate global eutrophication problems in aquatic ecosystems. This study in Lake Datong, China, investigates the remediation mechanism of multiple remediation technique combinations (dredging, adsorbent amendment, and planting aquatic vegetation) on sediment N and P loads based on two high-resolution sampling techniques (HR-Peeper and DGT) and P sequential extraction procedures. The results showed that high temperature and low dissolved oxygen considerably enhanced pore water dissolved reactive P (DRP) and NH4+ concentrations attributable to abundant Fe-P and organic matter content in the sediment. Fe reduction is critical for regulating pore water DRP release and promoting N removal. Overall, for Lake Datong, combining multiple remediation techniques is more effective in controlling sediment P loads (pore water DRP, P fluxes, forms of P, and labile P), from a long-term perspective, than a single remediation. Lanthanum-modified bentonite (LMB) inactivation treatment can transfer mobile P in the surface sediment into more refractory forms over time, thereby reducing the risk of sediment labile P release. However, it is difficult to effectively remediate internal P loads owing to inappropriate dredging depths and low biomass of aquatic vegetation. Future lake restoration practices should optimize the selection of different remediation technique combinations based on internal N and P pollution characteristics, while reducing external wastewater input. These results are important for understanding the remediation mechanisms of internal N and P and provide suggestions for sediment management of shallow eutrophic lakes.

Recycling different textile wastes for methane production: Morphological and microstructural changes and microbial community dynamics.

The dramatic increase of textile wastes has become a major global concern, which calls for alternative practices to alleviate severe environmental pollution and waste of resources due to their improper disposal and management. Anaerobic digestion (AD) is a cost-effective and eco-friendly technology that allows the bioconversion of organic wastes into clean energy (methane), which might be potentially useful for recycling textile wastes. In this study, AD was applied to 11 commonly available textile wastes in daily life to explore their feasibility, along with the methane production efficiency, biodegradability (BD), degradation mechanism, and microbial community dynamics during AD. The results showed that all textile wastes presented an obvious decomposition from an integrated shape to fragmented pieces within 18 days except blue denim. The highest experimental methane production (EMP) of 356.0 mL/g volatile solids (VS) and BD of 78.0 % were obtained with flax. The degradation mechanism could be concluded that predominant bacteria, especially Clostridium sensu stricto, first attached to the surface of textile waste and converted its main compositions cellulose and hemicellulose into acetate as the core intermediate. Then, acetate was utilized by the major methanogen, Methanothrix, through the acetoclastic methanogenesis pathway to produce methane. This study not only enriches the understanding of textile wastes degradation mechanisms during AD and provides very useful data on methane production from commonly available textile wastes but also proposes a promising method for efficiently recycling and utilizing the diverse range of textile wastes to reduce waste pollution and generate clean energy simultaneously.

Influences of organic loading, feed-to-inoculum ratio, and different pretreatment strategies on the methane production performance of eggplant stalk.

A large amount of eggplant stalk (ES) is incinerated after harvesting of eggplant every year, which aggravates environmental pollution and waste of resources. Converting ES into methane through anaerobic digestion (AD) technology may be a potential treatment method, considering the low environmental impact and high energy recovery. Firstly, this study explored the effects of organic loading (OL) and feed to inoculum ratio (F/I ratio) on the AD of ES by response surface methodology (RSM). In order to achieve higher AD efficiency, various pretreatments (acid, alkali, alkaline hydrogen peroxide (AHP), microwave, and ultrasound) were introduced and comprehensively assessed with regard to methane production, organic matter destruction, and kinetic parameters. Results showed that OL had a more significant impact on AD process compared to F/I ratio and methane production was enhanced remarkably when the OL and F/I ratio were 35.0 g VS/L and 3.0, respectively. XRD, FTIR, and SEM analyses of pretreated ES showed that alkali and AHP pretreatments performed better in delignification. Under optimal conditions, the ES pretreated with 1.5% AHP (adjusted by KOH) performed the maximum methane production of 262.2 mL/g VS with a biodegradability of 95.0%, which increased by 334.1% compared to untreated ES. This paper not only provides the theoretical data about methane production performance of ES but also gives practical guidance for efficient utilization of similar vegetable stalk biowastes, which is also promising for large-scale industrial applications in the future.

Response of spatio-temporal changes in sediment phosphorus fractions to vegetation restoration in the degraded river-lake ecotone.

Phosphorus (P) is an essential element in the ecosystem and the cause of the eutrophication of rivers and lakes. The river-lake ecotone is the ecological buffer zone between rivers and lakes, which can transfer energy and material between terrestrial and aquatic ecosystems. Vegetation restoration of degraded river-lake ecotone can improve the interception capacity of P pollution. However, the effects of different vegetation restoration types on sediment P cycling and its mechanism remain unclear. Therefore, we seasonally measured the P fractions and physicochemical properties of sediments from different restored vegetation (three native species and one invasive species). The results found that vegetation restoration significantly increased the sediment total P and bioavailable P content, which increased the sediment tolerance to P pollution in river-lake ecotone. In addition, the total P content in sediments was highest in summer and autumn, but lower in spring and winter. The total P and bioavailable P contents in surface sediments were the highest. They decreased with increasing depth, suggesting that sediment P assimilation by vegetation restoration and the resulting litter leads to redistribution of P in different seasons and sediment depths. Microbial biomass-P (MBP), total nitrogen (TN), and sediment organic matter (SOM) are the main factors affecting the change of sediment phosphorus fractions. All four plants' maximum biomass and P storage appeared in the autumn. Although the biomass and P storage of the invasive species Alternanthera philoxeroides were lower, the higher bioavailable P content and MBP values of the surface sediments indicated the utilization efficiency of sediment resources. These results suggest that vegetation restoration affects the distribution and circulation of P in river and lake ecosystems, which further enhances the ecological function of the river-lake ecotone and prevents the eutrophication and erosion of water and sediment in the river-lake ecotone.

[Advance in the degradation of biodegradable plastics in different environments].

With the continuously increasing demands of plastic products in the current society, the challenge of disposing plastic waste is constantly increasing, leading to the urgent need of mitigating plastic pollution. As a consequence, much attention has been paid to biodegradable plastics due to their degradability in a bio-active environment under certain conditions. Biodegradable plastics herald vast development potentials and considerable market prospects. The degradation of numerous types of biodegradable plastics will be affected by many factors. A thorough understanding of degradation mechanisms as well as functional microbial strains and enzymes is the key to comprehensive utilization and efficient treatment and disposal of biodegradable plastics. The article summarized the types, properties, advantages and disadvantages, and main applications of common biodegradable plastics. The degradation mechanisms, functional microbial strains and enzymes, as well as the degradation degree and duration under different environmental conditions, were also summarized. This review may help better understand the degradation of biodegradable plastics wastes.

Community structure and function of epiphytic bacteria attached to three submerged macrophytes.

In aquatic ecosystems, large amounts of epiphytic bacteria living on the leaf surfaces of submerged macrophytes play important roles in affecting plant growth and biogeochemical cycling. The restoration of different submerged macrophytes has been considered an effective measure to improve eutrophic lakes. However, the community ecology of epiphytic bacteria is far from well understood for different submerged macrophytes. In this study, we used quantitative PCR, 16S rRNA gene high-throughput sequencing and functional prediction analysis to explore the structure and function of epiphytic bacteria in an aquatic ecosystem recovered by three submerged macrophytes (Hydrilla verticillata, Vallisneria natans and Potamogeton maackianus) during two growth periods. The results showed that the community compositions and functions of epiphytic bacterial communities on the submerged macrophyte hosts were different from those of the planktonic bacterial communities in the surrounding water. The alpha diversity of the epiphytic bacterial community was significantly higher in October than in July, and the community compositions and functions differed significantly in July and October. Among the three submerged macrophytes, the structures and functions of the epiphytic bacterial community exhibited obvious differences, and some specific taxa were enriched on the biofilms of the three plants. The alpha diversity and the abundance of functions related to nitrogen and phosphorus transformation were higher in the epiphytic bacteria of P. maackianus. In summary, these results provide clues for understanding the distribution and formation mechanisms of epiphytic bacteria on submerged macrophyte leaves and their roles in freshwater ecosystems.

The spatiotemporal characteristics of water quality and phytoplankton community in a shallow eutrophic lake: Implications for submerged vegetation restoration.

One of the most serious consequences of eutrophication in shallow lakes is deterioration of water quality, proliferation of phytoplankton and disappearance of submerged macrophytes. After removing herbivorous and plankti-benthivorous fish, submerged macrophyte restoration was utilized at the entire lake (82.7 km2) to combat eutrophication and improve water quality in the shallow subtropical aquaculture of Lake Datong. We conducted two years of monitoring, from March 2018 to February 2020. During the first year of restoration, 80% of the area of Lake Datong (approximately 60 km2) was successfully recovered by submerged vegetation, and the water quality was improved. For example, the phosphorous (P) content (including total P (TP), dissolved reactive P (DRP) and total dissolved P (TDP)) and turbidity decreased, and the Secchi depth (SD) increased. However, the submerged vegetation disappeared from autumn 2019 in the intermittent recovery area (MN), while the continuous recovery area (DX) continued to recover with an abundance of submerged vegetation. During the second year, the water quality continued to improve significantly in the DX area, with high biomass and coverage of submerged vegetation. In the MN area, although turbidity and ammonia nitrogen (NH4+-N) increased significantly and SD decreased significantly, the P content (TP, TDP, and DRP) still continued to decrease. The restoration of submerged macrophytes could significantly decrease the density of phytoplankton. Over time, there was a regime shift in Lake Datong. The structural equation model (SEM) results illustrated that the water level and submerged plant coverage were the primary drivers that triggered changes in the state of the lake ecosystem. Our results highlight the potential of restoring submerged vegetation to control water eutrophication at the whole-lake scale. However, the water level in spring was the primary driver that triggered changes in the state of the lake ecosystem. Water level management should be emphasized during the early stages of recovery of submerged plants.

T2 MRI at 3T of cartilage and menisci in patients with hyperuricemia: initial findings.

OBJECTIVE: To compare and evaluate T2 values of compartmental femorotibial cartilage and subregional menisci in patients with hyperuricemia at 3T. MATERIALS AND METHODS: Thirty-two subjects were included in this study and subdivided into two subgroups: 15 healthy controls (3 females, 12 males; mean age = 45.3 ± 10.9 years), 17 patients with hyperuricemia (2 females, 15 males; mean age = 44.4 ± 12.7 years). All subjects were assessed on a 3T MR scanner using an 8-channel phased-array knee coil (transmit-receive). Wilcoxon rank sum test and analysis of covariance (ANCOVA) were performed to determine whether there were any statistically significant differences in T2 values of compartmental femorotibial cartilage and subregional menisci between the two subgroups. RESULTS: Lateral tibial cartilage (48.6 ± 3.5 ms) in healthy subgroup had significantly lower (p < 0.05) T2 values than all subcompartments of femorotibial cartilage in hyperuricemia subgroup. Medial tibial cartilage (56.5 ± 4.3 ms) in hyperuricemia subgroup had significantly higher (p < 0.05) T2 values than all subcompartments of femorotibial cartilage except medial tibial cartilage in healthy subgroup. Medial anterior horn of meniscus (39.4 ± 2.9 ms) in healthy subgroup had significantly lower (p < 0.05) T2 values than all subregional menisci except both medial anterior horn and medial body segment of meniscus in hyperuricemia subgroup. CONCLUSION: T2 values in certain compartmental femorotibial cartilage and subregional menisci in patients with hyperuricemia are evidently and abnormally heightened compared with those in healthy subjects, to which special attention should be paid when diagnosing and treating the patients with hyperuricemia in the clinical setting. The LT cartilage had significantly lower T2 values (48.6 ± 3.5 ms) in healthy subgroup compared to all compartmental femorotibial cartilage in cohort with HU. MF cartilage had significantly lower T2 values (51.6 ± 2.9 ms) in healthy subgroup compared to both LF (54.4 ± 4.1 ms) and MT (56.5 ± 4.3 ms) in cohort with HU. MT cartilage had significantly higher T2 values (56.5 ± 4.3 ms) in cohort with HU subgroup compared to LF (52.5 ± 3.0 ms) in healthy subgroup. T2 mapping may be promising and potential sensitive discriminator of understanding and examining the early compositional and structural change in proteoglycan-collagen matrix of human femorotibial cartilage in patients with hyperuricemia.

Wintertime vertical distribution of black carbon and single scattering albedo in a semi-arid region derived from tethered balloon observations.

The vertical distribution of atmospheric aerosols plays an essential role in aerosol-radiation and aerosol-cloud interactions. Because of strong light absorption, the radiative effects of black carbon (BC) are highly sensitive to its vertical distribution; the lack of high-resolution observations is the reason for their poor quantification. We used a tethered balloon platform to acquire high-resolution vertical profiles of BC, particle number concentration, and meteorological parameters in the semi-arid region of Northwest China in December 2018. A total of 112 BC profiles were classified into four vertical distribution categories, which were determined by local emissions, regional transport, vertical mixing due to the ABL evolution, and topography. BC profiles with peaks near or above the atmospheric boundary layer (ABL) accounted for 57% of the profiles. Vertical single scattering albedo (SSA) profiles were subsequently calculated using the profiles of BC and particle size distribution. The vertical SSA distribution is generally modulated by BC profiles. The diurnal variations of the BC and SSA profiles were summarized using a boundary-layer normalization method. In the ABL, BC decreased and SSA increased with increasing height at 02:00, 08:00, and 20:00, while both BC and SSA exhibited a uniform distribution at 14:00. The SSA decreased above the ABL at 14:00, which might have had a profound impact on ABL development. These results provide a better understanding of the vertical BC and SSA distributions, which can also be used to reduce uncertainties in estimating the BC radiative effects.

Recycling durian shell and jackfruit peel via anaerobic digestion.

With growing popularity of durian and jackfruit, environment threats following improper management of durian shell (DS) and jackfruit peel (JP) are increasingly serious. Anaerobic digestion is a potential solution but concern on its unsatisfied efficiency from lignocellulosic recalcitrance remains. This work applied four representative pretreatments on DS and JP to determine the effects on methane generation, energy potential, and environmental benefits. The suitable pretreatments for DS and JP were 3% KOH and 5% AHP, causing 103.8% and 69.8% increase in methane yield and biodegradability than untreated, respectively. Moreover, 3% KOH-treated DS and 5% AHP-treated JP could potentially produce total energy of 2.0 × 109 MJ/year, reduce coal consumption by 6.8 × 104 ton/year, and cut emission by 2.2 × 1010 particulate/year, which might alleviate the serious energy crisis and environmental issues from the overuse of fossil fuel. This study provides important insights into efficient use of DS and JP, and a reference for other fruit wastes.

Response of sediment and water microbial communities to submerged vegetations restoration in a shallow eutrophic lake.

Submerged macrophytes are the main primary producers in shallow lakes and play an important role in structuring communities. Aquatic microbes are also an important component of aquatic ecosystems and play important roles in maintaining the health and stability of ecosystems. However, little is known about the interactions between macrophytes and microbes during the reintroduction of submerged vegetation. Here, we chose restored zones dominated by four different submerged vegetations and a bare zone in a shallow eutrophic lake to unveil the microbial diversity, composition and structure changes in sediment and water samples after submerged macrophytes were recovered for one and a half years (July 2019) and two years (April 2020). We found that the recovery of submerged vegetations decreased phosphorus content in water and sediments but increased nitrogen and carbon content in sediments. We observed that the transparency of water in the restored zones was significantly higher than that in the bare zone in July. The recovery of submerged vegetations significantly influenced the alpha diversity of bacterial communities in sediments, with higher values observed in restored zones than in bare zones, whereas no significant influence was found in the water samples. In July, the macrophyte species showed strong effects on the bacterial community composition in water and relatively little effect in sediment. However, a strong effect of the macrophyte species on the composition of bacterial communities in sediments was observed in April, which may be related to the decomposition of plant litter and the decay of detritus. Additionally, the dissimilarity of the sedimentary bacterial community may increase more slowly with environmental changes than the planktonic bacterial community dissimilarity. These results suggest that the large-scale restoration of aquatic macrophytes can not only improve water quality and change sediment characteristics but can also affect the diversity and compositions of bacterial communities, and these effects seem to be very long-lasting.

High contribution of vehicle emissions to fine particulate pollutions in Lanzhou, Northwest China based on high-resolution online data source appointment.

The quantitative estimation of urban particulate matter (PM) sources is essential but limited because of various reasons. The hourly online data of PM2.5, organic carbon (OC), elemental carbon (EC), water-soluble ions, and elements from December 2019 to November 2020 was used to conduct PM source appointment, with an emphasis on the contribution of vehicle emissions to fine PM pollution in downtown Lanzhou, Northwest China. Vehicle emissions, secondary formation, mineral dust, and coal combustion were found to be the major PM sources using the positive matrix factorization model. The seasonal mean PM2.5 were estimated to be 72.8, 39.2, 24.3, and 43.6 µg·m-3 and vehicle emissions accounted for 35.7%, 25.8%, 30.0%, and 56.6% in winter, spring, summer, and autumn, respectively. Vehicle emissions were the largest source of PM considering the high PM pollution in winter and its significantly large contribution in autumn. Furthermore, the contribution of vehicle emissions increased with increasing PM in winter and autumn. Vehicle emissions were also the most important source of EC, accounting for 70.3%, 91.0%, 83.5%, and 93.7% of the total EC in winter, spring, summer, and autumn, respectively. With the reduction in industrial emissions and increase in vehicle numbers in China in recent years, vehicle emissions are going to be the largest source of urban PM pollution. To sustainably improve air quality in Lanzhou and other Chinese cities, efforts should be made to control vehicle emissions such as promoting clean-energy vehicles and encouraging public transportation.