All-optical Einstein-Podolsky-Rosen steering swapping.

Einstein-Podolsky-Rosen (EPR) steering, an important resource in quantum information, describes the ability of one party to influence the state of another party through local measurements. It differs from Bell nonlocality and entanglement due to its asymmetric property. EPR steering swapping allows two spatially independent parties to present EPR steering without direct interaction. Here, we theoretically propose an all-optical EPR steering swapping (AOSS) scheme based on low-noise high-broadband optical parametric amplifiers (OPAs). A low-noise high-broadband OPA is utilized to implement the function of Bell-state measurement without detection, avoiding the optic-electro and electro-optic conversions. After AOSS, one-way and two-way EPR steering between two independent optical modes can be obtained. Our scheme provides a guidance for the construction of a measurement-free, all-optical broadband quantum network utilizing EPR steering swapping.

[Characterization of Microplastic Surface Bacterial Community Structure and Prediction of Ecological Risk in Poyang Lake, China].

In recent years, the environmental pollution of microplastics in Poyang Lake has received increasing attention. Baisha Lake of Poyang Lake was selected as the study area, and samples of water and sediments of Baisha Lake and the microplastics therein were collected, and the polymer types of microplastics were identified as polyethylene (PE), polyester (PET), polypropylene (PP), and polystyrene (PS) using Fourier infrared spectroscopy. We also analyzed the structural composition of bacterial communities in water, in sediments, and on microplastic surfaces using 16S high-throughput sequencing. The species richness and diversity of bacteria on the microplastic surfaces were lower than those in the surrounding water and sediments. The results of NMDS analysis showed that the bacterial community structures on the microplastic surfaces differed greatly from those in the surrounding sediments and water. The bacterial community composition in water and sediment differed from that on the microplastic surfaces, and the dominant bacterial phyla on the microplastic surfaces were Proteobacteria and Bacteroidota, and their relative abundance on the microplastic surfaces was higher than that in sediment. The relative abundance of Proteobacteria was higher than that in water. The relative abundances of Bacteroidota and Actinobacteriota were significantly lower than that of water. Massilia and Pseudomonas were the dominant genera on the microplastic surfaces, and their relative abundances were significantly higher than those in the surrounding water and sediments. BugBase phenotype prediction revealed that the relative abundance of contains mobile elements, biofilm formation, potential pathogenicity, and stress tolerance phenotypes of microplastic bacterial communities were significantly higher than those of the surrounding water and sediments. The results revealed that microplastics may have contributed to the spread of harmful bacteria, including pathogenic bacteria, and increased the potential pathogenicity of bacterial communities. Additionally, microplastic surface bacterial communities had higher phenotypes of mobile gene element content. Revealing the potential harm of microplastic pollution to wetland ecology at the micro level may provide a scientific reference for maintaining the ecological stability of wetlands.

Enhancing and flattening multiplexed quantum entanglement by utilizing perfect vortex modes.

We experimentally demonstrate a method for enhancing and flattening multiplexed entanglement in the four-wave mixing (FWM) process, which is implemented by replacing Laguerre-Gaussian (LG) modes with perfect vortex (PV) modes. For the topological charge l ranging from -5 to 5, the entanglement degrees of orbital angular momentum (OAM) multiplexed entanglement with PV modes are all larger than those of OAM multiplexed entanglement with LG modes. More importantly, for OAM multiplexed entanglement with PV modes, the degree of entanglement almost does not change with the topology value. In other words, we experimentally flatten the OAM multiplexed entanglement, which cannot be achieved in OAM multiplexed entanglement with LG modes based on the FWM process. In addition, we experimentally measure the entanglement with coherent superposition OAM modes. Our scheme provides a new, to the best of our knowledge, platform to construct an OAM multiplexed system and may find potential applications in realizing the parallel quantum information protocols.

[Microbial Community Structure on Microplastic Surface in the Grus leucogeranus Reserve of Poyang Lake].

As a new type of pollutant, microplastics have attracted increasing attention. Microplastics in aquatic ecosystems are accumulating at an unprecedented scale, causing significant environmental and economic impacts. In this study, sediments and different types of microplastic samples were collected from the Grus leucogeranus Reserve of Wuxing Reclamation Farm of Poyang Lake, which is the largest freshwater lake in China. The main types of microplastics were film (PE), debris (PP1), fiber (PP2), and foam (PS), and the polymers were identified as polyethylene, polypropylene, and polystyrene in the study area. The structures of microbial communities (fungi and bacteria) were identified using 16S high-throughput sequencing. The results showed that there was no significant difference in the Ace and Chao of bacteria between the surface of PE and PP1 and that of the surrounding sediments (P>0.05), whereas PP2 and PS were significantly lower than those in surrounding sediments (P<0.05). Ace and Chao of fungi showed that PE and PS had no significant differences with the sediment (P>0.05), and PP1 and PP2 were significantly lower than those in surrounding sediments (P<0.05). The species diversity Shannon and Simpson index of bacteria and fungi on different types of microplastic surfaces were lower than that of sediment. The bacterial communities on the sediment and microplastic surface mainly included Proteobacteria and Bacteroidetes. In the fungal community, Basidiomycota, Ascomycota, and Chytridiomycota were the dominant bacteria. Through KEGG functional prediction, it was found that most of the metabolic pathways with a significant difference between bacteria and sediments on the surface of microplastics and with an abundance ratio higher than 1% were related to metabolism. Compared with that of sediment, the metabolic pathways of PE and PP2 on microplastic surfaces were down-regulated mainly in cell motility, signal transduction, and carbohydrate metabolism, whereas the energy metabolism, general and global metabolism pathways, and cofactor metabolism were up-regulated. Compared with that of sediment, the bacterial metabolic pathways of PS and PP1 on microplastic surfaces were down-regulated, mainly including general and global metabolic pathways, translation, and exogenous biodegradation, and cell motility and signal transduction were up-regulated. However, the abundance of other functional genes in sediments and microplastic samples showed little difference. The results indicated that microplastics can change the structure of microbial communities, and the microbial community on the surface of microplastics could catalyze metabolic reactions and promote the decomposition of microplastics. The study of microplastic surface microbial structure in Poyang Lake can support management decisions to protect the ecological integrity of the lake.

Seasonal flooding wetland expansion would strongly affect soil and sediment organic carbon storage and carbon-nutrient stoichiometry.

In the past few decades, many non-flooding uplands (NF) and permanent flooding waters (PF) have been turned into seasonal flooding wetlands (SF) at the global scale. This trend could severely threaten global climate system by changing carbon cycling in terrestrial and aquatic ecosystems. However, the effects of SF expansion on soil and sediment organic carbon (SOC) storage and carbon-nutrient stoichiometry are far from clearly understood. Therefore, we explored SOC storage and carbon-nutrient stoichiometry among adjacent NF, SF and PF using 817 samples at 0-100 cm depth increment at Poyang Lake and Shengjin Lake in the middle-lower Yangtze River floodplain, China. The SFs of the two lakes were both Carex lakeshore wetlands. The NF of Shengjin Lake was a near-natural forest, while the NF of Poyang Lake was a disturbed grassland. The results showed that SOC storage at SFs of Poyang Lake and Shengjin Lake was 75.61 and 98.01 Mg C/ha at 0-100 cm depth increment. The difference in SOC storage among nearby NF, SF and PF depended on depth and disturbance. SOC storage at SF was equivalent to that at near-natural NF, but was much higher than that at disturbed NF. SOC storage at SF was 12.62%-24.50% higher than that at PF at 0-30 cm depth increment, but was 15.16%-25.87% lower than that at PF at 0-100 cm depth increment. Edaphic carbon and nutrients followed allometric relationships at most sites and C increased faster than N and P along the depth gradients. Carbon-nutrient stoichiometric relationships at SF and PF were similar, and were more coupled than those at near-natural NF. This research illustrates the strong effects of seasonal flooding on SOC sequestration in terrestrial and aquatic ecosystems, and expands our understanding of carbon cycling in these two ecosystems.

A comparison of metric scoring and health status classification methods to evaluate benthic macroinvertebrate-based index of biotic integrity performance in Poyang Lake wetland.

Methods for metric scoring and health status classification in development of index of biotic integrity (IBI) vary considerably across published studies. The difference between ecosystem health assessment results from these alternative methods for scoring and classification has rarely been studied systematically. Poyang Lake in China has experienced severe degradation over recent decades. Here, we aimed to develop a benthic macroinvertebrate-based index of biotic integrity (B-IBI) to assess the wetland health of Poyang Lake, and to evaluate the difference in assessment results using different methods of scoring and classification. Data on benthic macroinvertebrate assemblages, water quality and human-induced disturbances were collected at 30 sampling sites. Forty-nine attributes of macroinvertebrate assemblages were tested, and only the attributes that were significantly correlated with disturbance gradients or showed strong discriminatory power between reference and impaired sites were selected as the B-IBI metrics. Two scoring, two thresholding and three classification methods were applied for metric scoring and health status classification. Five assemblage attributes, i.e. the number of taxa, Shannon-Wiener diversity index, % Diptera, ASPT index and the number of predator taxa, were selected as the B-IBI metrics. Health status assessments varied considerably among the various metric scoring and classification methods, suggesting the importance of standardizing the methods for scoring and classification to be able to compare assessment results across different areas and time periods. The wetland health of Poyang Lake was rated as fair, which indicates that the wetland has experienced anthropogenic pressure and substantial changes in macroinvertebrate assemblage structure. Further, sample sites adjacent to tributary river mouths were in poor or very poor condition, suggesting that pollutant input by rivers has strong negative impacts on wetland health. Effective management of the entire lake basin and its watershed is therefore important for the wetland conservation.

Taxonomic bias in occurrence information of angiosperm species in China.

Taxonomic bias is a well-known shortcoming of species occurrence databases. Understanding the causes of taxonomic bias facilitates future biological surveys and addresses current knowledge gaps. Here, we investigate the main drivers of taxonomic bias in occurrence data of angiosperm species in China. We used a database including 5,936,768 records for 28,968 angiosperm species derived from herbarium specimens and literature sources. Generalized additive models (GAMs) were applied to investigate explanatory powers of 17 variables on the variation in record numbers of species. Five explanatory variables were selected for a multi-predictor GAM that explained 69% of the variation in record numbers: plant height, range size, elevational range, numbers of scientific publications and web pages. Range size was the most important predictor in the model and positively correlated with number of records. Morphological and phenological traits and social-economic factors including economic values and conservation status had weak explanatory powers on record numbers of plant species, which differs from the findings in animals, suggesting that causes of taxonomic bias in occurrence databases may vary between taxonomic groups. Our results suggest that future floristic surveys in China should more focus on range-restricted and socially or scientifically less "interesting" species.

Flooding variations affect soil bacterial communities at the spatial and inter-annual scales.

Hydrological variations have substantial effects on the diversity and composition of soil bacterial communities in wetlands. At the spatial scale, the responses of soil bacterial diversity and composition to hydrological variations in wetlands have been extensively investigated. However, at the temporal scale, especially at the inter-annual scale, the corresponding bacterial responses are rarely reported. Therefore, we explored the effects of flooding variations on the diversity and composition of soil bacterial communities at a lakeshore wetland in two hydrological contrasting years. Three flooding variables, i.e. flooding duration (FD), total duration of the growing season (TGD), and exposure duration of the growing season (EGD), were used to characterize flooding regime. Soil bacterial communities were determined using 16S rRNA gene sequencing method. We found a very high soil bacterial diversity at the lakeshore wetland. The Shannon's indexes of soil bacterial communities varied from 5.61 to 7.11 in two years. Soil bacterial α-diversity followed a unimodal curve along the elevation gradient, and was significantly lower in the flooding year than in the drought year. Principal coordinate analysis demonstrated that the compositions of soil bacterial communities were separated in order of elevation and year along the first and second axes, respectively. The apparent habitat preferences of soil bacterial families were closely connected with their respiratory traits, and this trend was stronger at the inter-annual scale than at the spatial scale. Soil bacterial compositions were predominantly determined by the direct (by changing respiratory traits) and indirect (by changing soil pH) effects of TGD at the spatial scale, while they were simultaneously regulated by the direct effects of three flooding variables at the inter-annual scale. Our results enhance the understanding of soil microbial communities in wetlands and have large implications for developing general theories to predicting soil microbial functions.

[Effect of degradation succession process on the temperature sensitivity of ecosystem respiration in alpine Potentilla fruticosa scrub meadow].

Grazing is one of the main artificial driving forces for the degradation succession process of alpine meadow. In order to quantitatively study the temperature sensitivity of alpine meadow ecosystem respiration in different degradation stages, we conducted the research in Haibei Alpine Meadow Ecosystem Research Station, CAS from July 2003 to July 2004. The static chamber-chromatography methodology was used to observe the seasonal changes of alpine scrub ecosystem respiration flux during different degradation stages. The results showed that: (1) The seasonal changes of ecosystem respiration flux in different degradation stages of alpine shrub presented a unimodal curve. The maximum appeared in August and the minimum appeared during the period from October to next April. The degradation succession process significantly decreased the ecosystem respiratory CO2 release rate. The respiratory rate ranges of alpine Potentilla fruticosa scrub (GG), Kobresia capillifolia meadow (GC) and bare land (GL) were 34.21-1 168.23, 2.30-1 112.38 and 20.40-509.72 mg (m2 x h)(-1), respectively. The average respiration rate of GG was 1.29 and 2.56 times of that of GC and GL, respectively; (2) Temperature was the main factor that affected the ecosystem respiration rate, and contributed 25% - 79% of the variation of the ecosystem respiration. The degradation succession process significantly changed the correlation between ecosystem respiration rate and temperature. The correlation (R2) between ecosystem respiration rate and each temperature indicator (T(s), T(d) and T(a)) was reduced by 47.23%, 46.95% and 55.28%, respectively when the ground vegetation disappeared and the scrub was degraded into secondary bare land; (3) The difference of Q10 between warm and cool seasons was significant (P < 0.05), and the value of cold season was larger than that of warm season. Degradation succession process apparently changed the temperature sensitivity of ecosystem respiration. The Q10 values of GG, GC and GL were 2.38, 2.91 and 1.62, respectively. Q10 of GC was increased by 22.26% and that of GL was decreased by 31.93% compared with that of GG.

[Research and demonstration of comprehensive measures of schistosomiasis prevention and control technology. II. Longitudinal evaluation on control effect].

OBJECTIVE: To evaluate the effect of comprehensive measures of schistosomiasis prevention and control technique. METHODS: The comprehensive measures including forbidding grazing on marshlands, renovating latrines and supplying safe water, and health education were carried out in a demonstrative area, and the schistosomiasis endemic situation and other relative factors were investigated. RESULTS: After the control measures were carried out for 3 years, the prevalence of schistosomiasis in human decreased from 3.57% to 0.83%, and the infection rates of cattle decreased from 17.14% to 0. No infected Oncomelania snails were found on the marshlands in the demonstration area. CONCLUSION: The comprehensive measures aforementioned are effective in the control of schistosomiasis in Poyang Lake region.

[Characteristics of CO2 emission from Carex-dominated wetland in Poyang Lake in non-flooded period].

By using static chamber/gas chromatography, the CO2 fluxes in a Carex cinerascen-dominated wetland in the Poyang Lake Nanji Wetland National Nature Reserve were measured in nonflooded period (from September 2009 to April 2010). Two treatments were installed, i. e. , soil-plant system (TC) and aboveground plant removal (TJ), representing ecosystem respiration and soil respiration, respectively. There was an obvious seasonal variation in the ecosystem respiration and soil respiration. The respiration rate in treatment TC ranged from 89.57 to 1243.99 mg CO2 x m(-2) x h(-1), and that in TJ was from 75.30 to 960.94 mg CO2 x m(-2) x h(-1). Soil respiration accounted for 39% -84% of ecosystem respiration, with an average of 64%. Soil temperature was the main factor controlling the ecosystem respiration and soil respiration, explaining more than 80% of the respiration variance. The temperature coefficient (Q10), an index of temperature sensitivity for respiration, was 3.31 for ecosystem respiration and 2.75 for soil respiration. The Q10 value was higher in winter than in autumn and spring. No significant correlation was observed between soil moisture and CO2 fluxes. In non-flooded period, the C. cinerascens-dominated wetland acted as a carbon sink of atmospheric CO2, with a carbon uptake of 1717.72 g C x m(-2).

Water sources of dominant species in three alpine ecosystems on the Tibetan Plateau, China.

Plant water sources were estimated by two or three compartment linear mixing models using hydrogen and oxygen isotope (deltaD and delta18O) values of different components such as plant xylem water, precipitation and river water as well as soil water on the Tibetan Plateau in the summer of 2005. Four dominant species (Quercus aquifolioides, Pinus tabulaeformis, Salix rehderiana and Nitraria tangutorum) in three typical ecosystems (forest, shrub and desert) were investigated in this study. Stable isotope ratios of the summer precipitations and the soil water presented variations in spatial and temporal scales. delta18O values of N. tangutorum xylem water were constant in the whole growth season and very similar to those of deep soil water. Water sources for all of the plants came from both precipitations and soil water. Plants switched rapidly among different water sources when environmental water conditions changed. Rainwater had different contributions to the plants, which was influenced by amounts of precipitation. The percentage of plant xylem water derived from rainwater rose with an increase in precipitation. Water sources for broad-leaved and coniferous species were different although they grew in the same environmental conditions. For example, the broad-leaved species Q. aquifolioides used mainly the water from deep soil, while 92.5% of xylem water of the coniferous species P. tabulaeformis was derived from rainwater during the growth season. The study will be helpful for us to fully understand responses of species on the Tibetan Plateau to changes in precipitation patterns, and to assess accurately changes of vegetation distribution in the future.

Growing season ecosystem respirations and associated component fluxes in two alpine meadows on the Tibetan Plateau.

From 30 June to 24 September in 2003 ecosystem respiration (Re) in two alpine meadows on the Tibetan Plateau were measured using static chamber- and gas chromatography- (GC) based techniques. Simultaneously, plant removal treatments were set to partition Re into plant autotrophic respiration (Ra) and microbial heterotrophic respiration (Rh). Results indicated that Re had clear diurnal and seasonal variation patterns in both of the meadows. The seasonal variability of Re at both meadow sites was caused mainly by changes in Ra, rather than Rh. Moreover, at the Kobresia humilis meadow site (K_site), Ra and Rh accounted for 54% and 46% of Re, respectively. While at the Potentilla fruticosa scrub meadow (P_site), the counterparts accounted for 61% and 39%, respectively. T test showed that there was significant difference in Re rates between the two meadows (t = 2.387, P = 0.022). However, no significant difference was found in Rh rates, whereas a significant difference was observed in Ra rates between the two meadows. Thus, the difference in Re rate between the two meadows was mainly attributed to plant autotrophic respirations. During the growing season, the two meadows showed relatively low Q10 values, suggesting that Re, especially Rh was not sensitive to temperature variation in the growing season. Additionally, Re and Rh at the K_site, as well as Rh at the P_site was negatively correlated with soil moisture, indicating that soil moisture would also play an important role in respirations.