Top-down effect of arthropod predator chinese mitten crab on freshwater nutrient cycling

Aquatic litter decomposition is highly dependent on contributions and interactions at different trophic levels. The invasion of alien aquatic organisms like the channeled apple snail (Pomacea canaliculata) might lead to changes in the decomposition process through new species interactions in the invaded wetland. However, it is not clear how aquatic macroinvertebrate predators like the Chinese mitten crab (Eriocheir sinensis) will affect the nutrient cycle in freshwater ecosystems in the face of new benthic invasion. We used the litter bag method to explore the top-down effect of crabs on the freshwater nutrient cycle with the help of soil zymography (a technology previously used in terrestrial ecosystems). The results showed significant feeding effects of crabs and snails on lotus leaf litter and cotton strips. Crabs significantly inhibited the intake of lotus litter and cotton strips and the ability to transform the environment of snails by predation. Crabs promoted the decomposition of various litter substrates by affecting the microbial community structure in the sediment. These results suggest that arthropod predators increase the complexity of detrital food webs through direct and indirect interactions, and consequently have an important impact on the material cycle and stability of freshwater ecosystems. This top-down effect makes macrobenthos play a key role in the biological control and engineering construction of freshwater ecosystems.Sincere thanks to the Jiangsu Provincial Department of Agriculture (JBGS [2021]126), Jiangsu Provincial Department of Science and Technology (BE2019393), Jiangsu Forestry Science and Technology Innovation and Promotion project (LYKJ [2021]16), and Portuguese Foundation for Science and Technology (FCT) through SFRH/BD/119957/2016 scholarship for supporting this study financially. Thanks also to the Jiangsu Provincial Platform for Conservation and Utilization of Agricultural Germplasm for supporting this study

Comparative study of Al2O3, SiO2 and TiO2-coated LiNi0.6Co0.2Mn0.2O2 electrode prepared by hydrolysis coating technology

In this work, Al, Si and Ti oxides are used to modify the surface of LiNi0.6Co0.2Mn0.2O2 (NCM622) electrode through the hydrolysis coating technology. SEM and TEM results revealed that three prepared oxide layers have different uniformity and morphology. Also, charge-discharge results showed different initial discharge capacity and cycle ability of three different oxide coatings. It is shown that when the temperature is increased from 25 to 50 °C, the capacity retention of Al2O3-coated NCM622 is reduced by only 4 %, what demonstrated the best ability of this oxide to restrain cycle deterioration. Additionally, when the charge cutoff voltage is increased to 4.6 V, Al2O3-coated NCM622 showed 74 % of capacity retention. As the number of charge-discharge cycles increases, the dissolution of some transition metal ions may be restrained by Al2O3 layer. Generally, the enhanced electrochemical performance of Al2O3-coated NCM622 could be ascribed to the suppression of mutual reaction between electrode and electrolyte and improvement of structural stability of the material by Al2O3 coating

Can water temperature impact litter decomposition under pollution of copper and zinc mixture

To better understand the impact of warming on heavy metals (HM) associated with plant litter decomposition in streams, we investigated the impact of high and low HM (Cu and Zn) levels and different water temperatures (10,15 and 20oC) on microbial decomposition of TyphaangustifoliaL.litter and the associated extracellular enzyme activities. During a 100-day incubation, changes in litter mass losses, chemical composition (lignin and total carbohydrate), and extracellular enzyme activity were determined. The decomposition rates were accelerated by the low HM levels at 20oC (0.0051 day–1 at CK vs 0.0061 day–1 at low HM levels). The negative effects of Cu and Zn on Typha litter decomposition were more pronounced at lower temperatures (10 and 15°C). The enhanced enzyme activities of cellulase and β-glucosidase and the higher lignin/litter weight loss and lignin/carbohydrate ratios were found at 20oC and low HM treatment. The enzyme activities of β-glucosidase and cellulase were positively correlated with litter mass losses at 20oC and low HM levels. These results suggest that a 5oC increase in water temperature may attenuate the inhibition of low HM level on litter decomposition

Characterization of the complete chloroplast genome of Oxytropis aciphylla Ledeb. (Leguminosae)

To better understand the taxonomy of the genus Oxytropis, we sequenced the complete chloroplast genome of Oxytropis aciphylla Ledeb. The total plastome of O. aciphylla Ledeb. is 122,121 bp in length with a GC content of 34.3%. It contains one large single-copy (LSC) region of 88,235 bp, one small single-copy (SSC) region of 10,400 bp, and one inverted repeat (IR) region of 23,486 bp, encoding 76 proteins, four rRNAs, and 29 tRNAs. The phylogenetic position shows that O. aciphylla Ledeb. is the closest to Oxytropis glabra

The Impact of Water-Soluble Inorganic Ions in Particulate Matter (PM2.5) on Litter Decomposition in Chinese Subtropical Forests

Although numerous studies have demonstrated the toxic effects of fine particulates less than 2.5 µm (PM2.5) on the health of humans, little information is available on the ecotoxicity of PM2.5. Water-soluble inorganic ions (WSII, including Na+, NH4+, K+, Mg2+, Ca2+, Cl−, NO3−, and SO42−) can compose more than 60% of PM2.5. To better understand the possible impacts of WSII-PM2.5 on leaf litter decomposition, we conducted an experiment in which two leaf litters from oak (Quercus variabilis) and pine (Pinus massoniana) dominant forests in subtropical China were incubated in microcosms containing their respective forest soils and treated with WSII-PM2.5. Our results showed that, after six-months of decomposition, the WSII-PM2.5 treatments inhibited leaf litter decomposition rates, carbon and nitrogen loss, microbial biomass, and enzyme activities in the two forests. In addition, higher WSII-PM2.5 concentration led to stronger negative effects. Comparative analysis showed that the negative effects of WSII-PM2.5 on oak forest were greater than on pine forest, relating to the higher susceptibility to changes of soil microenvironment in oak forests. WSII-PM2.5 may influence decomposition through soil acidification and salinization, which could also cause a sub-lethal depression in soil isopod activity. However, in the first month of decomposition, mass loss of the oak and pine leaf litters under the low concentration WSII-PM2.5 were 21.63% and 35.64% higher than that under the control, respectively. This suggests that transitory low concentrations of WSII-PM2.5 have a promoting effect on decomposition. Long-term PM2.5 exposure, therefore, may have profound ecosystem consequences by altering the balance of ecosystem carbon flux, nutrient cycling, and humus formation in the future

The importance of calcium in improving resistance of Daphnia to Microcystis.

Changing environmental calcium (Ca) and rising cyanobacterial blooms in lake habitats could strongly reduce Daphnia growth and survival. Here, we assessed the effects of maternal Ca in Daphnia on transfer of resistance to their offspring against Microcystis aeruginosa PCC7806 (M. aeruginosa). Laboratory microcosm experiments were performed to examine effects in Daphnia carinata (D. carinata) and Daphnia pulex (D. pulex), and that how Ca induce responses in their offspring. The results showed that growth and survival were increased in offspring from exposed Daphnia as compared to unexposed, when raised in high Ca and increasing M. aeruginosa concentration. Among exposed Daphnia, offspring from high Ca mothers, produced more neonates with large size and higher survival as compared to offspring from low maternal Ca. Exposed D. carinata and D. pulex offspring, when reared in Ca deficient medium and increasing M. aeruginosa concentration, time to first brood increased, size become large and total offspring decreased subsequently in three alternative broods in offspring from low maternal Ca. In contrast, growth and reproduction in offspring from high Ca exposed mothers were consistent in three alternative broods. Despite species specific responses in growth, survival and variant life history traits in two Daphnia species, our results not only show maternal induction in Daphnia but also highlight that offspring response to M. aeruginosa varies with maternal Ca. This study demonstrates that Ca have role in Daphnia maternal induction against Microcystis, and recent Ca decline and increasing Microcystis concentration in lakes may decrease Daphnia growth and survival. Our data provide insights into the interactive effect of maternal Ca and Microcystis exposure on Daphnia and their outcome on offspring life history traits and survival

Impacts of Inter-Basin Water Transfer Projects on Optimal Water Resources Allocation in the Hanjiang River Basin, China

Inter-basin water transfer project is an effective engineering countermeasure to alleviate the pressure of water supply in water-deficient areas and balance the uneven distribution of water resources. To assess the impacts of inter-basin water transfer projects on optimal water resources allocation, an integrated water resources management framework is proposed, and is applied to the middle and lower reaches of the Hanjiang River Basin in China. Firstly, future water demands are analyzed as inputs. Then, a multi-objective water resources allocation model is formulated mitigating the negative impacts of water transfer projects on downstream water quantity and quality by using the non-dominated sorting genetic algorithm-II (NSGA-II). Finally, the indicators of water supply reliability, vulnerability and resilience are evaluated under different scenarios of inter-basin water transfer projects. The results indicate that: (1) the reliability and resilience of the water donor system will be gradually reduced while the vulnerability will be increased with the expansion of water transfer projects and the increase of water demand, (2) water supply risk is likely to increase in all zones (because zones at the boundary cannot obtain sufficient water due to limitations of local inflow and reservoir operation, while the amount of water available in the zones along the mainstream river is directly decreased by the water transfer projects), (3) more water supply measures and compensation measures will need to be implemented in the water donor areas. The framework proposed in this study to evaluate the comprehensive impact of inter-basin water transfer projects is conducive to water resources management

SPWM Smoothing Control Method Based on Wind Power Grid Connection

Energy is the foundation of economic development and technological development. Facing the present situation of non-renewable energy decline, wind power generation has been developed rapidly. However, the problem of unstable output voltage of wind power generation due to unstable wind speed needs to be solved, and traditional solutions cannot make the generated electric energy meet the national standards for grid-connected and off-grid operation. In this paper, the electric energy generated by wind turbine is rectified by bridge rectifier circuit and using large capacity capacitor filtering to generate DC with flat waveform. Then, using SPWM inversion technology, the normal rotation wave with the same frequency as the power grid is used as the modulation wave and according to the required voltage amplitude, and the triangle wave with appropriate duty ratio is calculated by SPWM smoothing control theory as carrier wave. Subsequently, accurate filtering is carried out and grid-connected and off-grid operation is carried out through the self-aligning device. Finally, with the help of MATLAB simulation platform, the wind turbine is simulated to work under different wind conditions, and whether the generated electric energy meets the grid-connected and off-grid operation standards is judged, which further determines the reliability and authenticity of the theory

The Photodegradation of Lignin Methoxyl C Promotes Fungal Decomposition of Lignin Aromatic C Measured with 13C-CPMAS NMR

Solar radiation has been regarded as a driver of litter decomposition in arid and semiarid ecosystems. Photodegradation of litter organic carbon (C) depends on chemical composition and water availability. However, the chemical changes in organic C that respond to solar radiation interacting with water pulses remain unknown. To explain changes in the chemical components of litter organic C exposed to UV-B, UV-A, and photosynthetically active radiation (PAR) mediated by water pulses, we measured the chemistry of marcescent Lindera glauca leaf litter by solid-state 13C cross-polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) over 494 days of litter decomposition with a microcosm experiment. Abiotic and biotic factors regulated litter decomposition via three pathways: first, photochemical mineralization of lignin methoxyl C rather than aromatic C exposed to UV radiation; second, the biological oxidation and leaching of cellulose O-alkyl C exposed to PAR and UV radiation interacts with water pulses; and third, the photopriming effect of UV radiation on lignin aromatic C rather than cellulose O-alkyl C under the interaction between radiation and water pulses. The robust decomposition index that explained the changes in the mass loss was the ratio of aromatic C to O-alkyl C (AR/OA) under radiation, but the ratio of hydrophobic to hydrophilic C (hydrophobicity), the carbohydrate C to methoxyl C ratio (CC/MC), and the alkyl C to O-alkyl C ratio (A/OA) under radiation were mediated by water pulses. Moreover, the photopriming effect and water availability promoted the potential activities of peroxidase and phenol oxidase associated with lignin degradation secreted by fungi. Our results suggest that direct photodegradation of lignin methoxyl C increases microbial accessibility to lignin aromatic C. Photo-oxidized compounds might be an additional C pool to regulate the stability of the soil C pool derived from plant litter by degrading lignin methoxyl and aromatic C