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• The ecohydraulic modeling framework is a valuable tool for assessing fish ecology in dammed rivers. • Cascade dam construction could fragment spawning site habitats and reduce fish population abundance in the tailwater zone of the main stream. • Spawning site habitats would improve, leading to an increase in fish population abundance in the backwater zone of tributaries. • The effects of cascade dam construction on endemic fish habitat and population status depend on spawning site location, fish species, and life stages. Cascade dam constructions will alter the habitat of spawning sites and affect fish population in the Lancang River basin. This paper examines the impacts of cascade dam construction on four spawning sites, focusing on two co-distributed and endemic fish species: Schizothorax prenanti and Schizothorax davidi. An ecohydraulic modeling framework that combined hydro-morphodynamic, habitat, and population models was used to investigate changes in habitat quality and fish population under two scenarios: no-dam and with-dam. Fish habitat quality was evaluated using the habitat suitability index, and population fluctuations were assessed by the abundance and density of fish populations at all life stages. The simulation results indicated that cascade dam construction would fragment the spawning site habitat in the tailwater zone of the main stream and result in a decrease in fish population abundance and density. Conversely, spawning site habitats in backwater zone of tributaries would improve, and fish population abundance and density would increase. Additionally, the simulation results showed that the magnitude of fish population variations varied by species and life stages. These results highlight the different responses of spawning site location, fish species, and life stages to dam construction, which can help identify areas of the habitat with higher potential for finer-scale endemic fish conservation and recovery efforts. This study provides a comprehensive framework tool for fish ecological evaluation in dammed rivers, which has the potential to assist decision-makers involved in river ecosystem ecological conservation. [Display omitted] [ABSTRACT FROM AUTHOR]

• HDR-CRISPR/Cas9D10A with four sgRNAs appeared to have higher knock-in efficiency in PRV. • The deletion of TK/gI/gE resulted in much antigenic epitope loss. • The insertion of GM-CSF enhanced the immunogenicity of the recombinant PRV. • The TK/gI/gE deleted PRV expressing GM-CSF alleviated the tissue damages in mice. Outbreaks of Pseudorabies (PR) by numerous highly virulent and antigenic variant Pseudorabies virus (PRV) strains have been causing severe economic losses to the pig industry in China since 2011. However, current commercial vaccines are often unable to induce thorough protective immunity. In this study, a TK/gI/gE deleted recombinant PRV expressing GM-CSF was developed by using the HDR-CRISPR/Cas9 system. Here, a four-sgRNA along with the Cas9D10A targeting system was utilized for TK/gI/gE gene deletion and GM-CSF insertion. Our study showed that the four-sgRNA targeting system appeared to have higher knock-in efficiency for PRVs editing. The replication of the recombinant PRVs were slightly lower than that of the parental strain, but they appeared to have similar properties in terms of growth curves and plaque morphology. The mice vaccinated with the recombinant PRV expressing GM-CSF via intramuscular injection showed no obvious clinical symptoms, milder pathological lesions, and were completely protected against wild-type PRV challenge. When compared to the triple gene-deleted PRV, the gB antibodies and neutralizing antibody titers were improved and the immunized mice appeared to have lower viral load and higher mRNA levels of IL-2, IL-4, IL-6, and IFN-γ in spleens. Our study offers a novel approach for recombinant PRV construction, and the triple gene-deleted PRV expressing GM-CSF could serve as a promising vaccine candidate for PR control. [ABSTRACT FROM AUTHOR]

• Using radioactive and stable water isotopes to quantify the water age and SGD. • SFGD was estimated by combining water and salt mass balance models. • The SFGD accounted for 4.5% of the total SGD. • SGD associated nutrient fluxes were significantly higher than riverine input. • The estimated water age of Laizhou Bay ranged from 23.5 to 50.0 days. Nutrient inputs from submarine groundwater discharge (SGD) play a significant role in sustaining primary productivity and nutrient cycling in the coastal area. Currently, various geochemical isotopes are used to trace the SGD processes. However, mass balance models of stable water isotopes (δ2H and δ18O) are seldom used in SGD estimating. In this study, mass balance models of 18O and radium (228Ra) isotopes were used to quantify the water age and SGD in Laizhou Bay, China based on the isotope data sampled in August 2017. The estimated age of water masses in Laizhou Bay ranged from 23.5 to 50.0 days with an average of 32.1 ± 16.3 days. The average SGD flux was (2.07 ± 1.04) × 108 m3 d−1, which was an order of magnitude larger than the Yellow River discharge during the sampling period. The sensitivity analysis revealed that estimated results of the water age and SGD are sensitive to the δ18O value in evaporation, as well as δ18O and 228Ra values in groundwater end-members. Based on the isotope method, the proportion of the Yellow River discharging into Laizhou Bay was estimated to be less than 27% of the total discharge. Furthermore, based on water and salt mass balance models, the estimated submarine fresh groundwater discharge (SFGD) flux ranged from (0.54–1.31) × 107 m3 d−1 with an average of (0.93 ± 0.46) × 107 m3 d−1. The SFGD accounted for 4.5% of the total SGD. Nutrient fluxes from SGD were significantly greater than those from the Yellow River, and SGD may have important effects on the marine ecosystem environments. This study reveals that stable and radium isotopes can be effectively combined to calculate the water age and SGD, which may be applied to the coastal area elsewhere. [ABSTRACT FROM AUTHOR]

Fe, Co, N atoms co-doped hollow carbon capsules was prepared and used as metal-free catalysts for PMS activation. In Fenton-like reaction, it displayed high degradation rate and outstanding adaptation to full pH range (0–14). [Display omitted] • Fe-Co-N@HCCs displays high PMS activation property in a full range of pH values. • k of Fe-Co-N@HCC is 3.1 and 1.4 times higher than N@HCCs and Fe-N@HCCs. • Contribution of radicals, 1O 2 , electron-transfer path is 13.3%, 30.1%, 56.6%. • PMS is activated on Fe-N 4 and Co-N 4 sites for 1O 2 , Co-N 4 site shows better activity. • Leached Fe and Co ions is 24.9 and 13.6 times lower than Fe-Co-N@HCCs/FeCo. Persulfate (PMS)-based Fenton-like reaction was a highly efficient technique for disposal of organic contaminants. However, high metal leaching and low environmental adaptation were the major concerns for further application. To overcome these two drawbacks, herein, Fe, Co, N atoms co-doped hollow carbon capsules (Fe-Co-N@HCCs) were prepared and used as catalysts for PMS activation. 92.6% of TC was degraded within 40 min and the mineralization efficiency was 55.7%. The degradation rate was 4.7, 3.1 and 1.4 times higher than those of activated carbon, N@HCCs, and Fe-N@HCCs, respectively. Thermodynamic study indicated the TC degradation was an exothermal, chaotic and non-spontaneous process. Radical trapping experiments, electron paramagnetic resonance spectrum, and electrochemical analysis indicated that 1O 2 production and electron-transfer path worked together for PMS activation. DFT calculation indicated that the catalytic activity of Co-N 4 site was higher than Fe-N 4 site for 1O 2 production. Fe-Co-N@HCCs were adapted well to the full pH range (0–14) and complex inorganic anions via non-radical PMS activation paths. Meanwhile, the leached Fe and Co ions were lowered to 0.201 and 0.457 mg/L, satisfying the China emission standard. This work gave a better comprehension on preparation of carbonaceous materials with high environmental adaptation and low leached metal ions for PMS activation. [ABSTRACT FROM AUTHOR]

Many coal mining subsidence lakes have formed in eastern China due to underground coal mining. Lacustrine groundwater discharge (LGD) is of great importance to the hydrological cycle and the eco-environment of lakes. However, LGD in coal mining area is rarely reported. In the study, we quantified groundwater discharge into a Huainan coal mining subsidence lake (China) using water stable (D and 18O) and radioactive (222Rn) isotopes. 222Rn and 18O mass balance models were used to independently estimate LGD. The lake water was sampled based on the horizontal and vertical profile sampling. The isotope depth profiles were weighted according to the lake bathymetry to obtain a representative isotope inventory by geographic information system (GIS) analysis. The LGD rates estimated from two models were comparable, and the values were 18 mm d−1 for the 18O and 14 ± 8 mm d−1 for the 222Rn. Compared with the LGD of Ammelshainer See lake (Germany), a subsidence lake formed by coal mining, the LGD in the study was larger, which may be related to the different hydrological conditions in different areas. By integrating the LGD rates from these two models, this study quantitatively analyzed the role of groundwater in maintaining the water balance in subsidence lakes, which is of great significance to water resources assessment and sustainable utilization of coal mining subsidence lakes in eastern China. • Using radioactive and stable isotopes to estimate LGD rate of the coal mining subsidence lake. • Combining horizontal and vertical sampling improves the accuracy of radon decay loss assessment. • Isotope depth profile is weighted to obtain representative isotope inventory. • Groundwater discharge contributes a large amount of water to coal mining subsidence lakes. [ABSTRACT FROM AUTHOR]

Large-scale gully land consolidation projects have been implemented on the Loess Plateau of western China. These projects have formed a large number of fill slopes, which are prone to failure induced by rainfall. However, the failure mechanisms of the loess-bedrock fill slope, especially the influence of the weak interlayer between the loess fill and bedrock on slope failure, are not clear. In this study, a laboratory flume model experiment was carried out to investigate rainfall infiltration processes and failure mechanisms of a loess-bedrock fill slope induced by rainfall. The volumetric water content, pore water pressure, wetting front migration, and deformation characteristics of the slope were analyzed to reveal the effects of the weak interlayer on slope failure. The results show that rainfall-induced failure of loess-bedrock fill slope exhibited characteristics of mode transformation, initiated by the local failure of the slope toe and gradually transforming into a multi-stage rotational slide-earthflow and gully erosion with continued rainfall. The maximum migration rate of the wetting front in the weak interlayer is about 3 times that in loess fill, occurring in the weak interlayer within a depth of 0.64 m (about 16 m in the prototype). The preferential flow formed in the weak interlayer accelerated the saturation of the fill slope and generated seepage force towards the outside of the slope, which makes the upper fill slope more prone to shear failure along the weak interlayer. These results provide a theoretical basis for preventing or mitigating related risks associated with gully land consolidation projects on the Loess Plateau. • A model test is used to study infiltration process and failure mechanisms of loess-bedrock fill slope induced by rainfall. • The effect of weak interlayer between bedrock and loess fill on the failure of loess-bedrock fill slope is analyzed. • Moisture migration of the loess-bedrock fill slope during rainfall is revealed. • The failure mode of loess-bedrock fill slope induced by rainfall is identified. [ABSTRACT FROM AUTHOR]

[Display omitted] • Seasonal sampling of heavy metals in the groundwater was conducted in a subtropical mangrove wetland. • The enrichment trend of heavy metals exhibited seasonal variations along the intertidal transect. • COVID-19-induced attenuation of anthropogenic activity reduced terrestrial input of heavy metals to the sea. • The intertidal aquifer served as a buffer zone for the transport of heavy metals to the sea. Mangrove wetlands connecting the land and sea are critical and dynamic ecosystems which act as biogeochemical reactors that influence the concentrations and distributions of heavy metals in the groundwater and adjacent seawater. In this paper, a subtropical mangrove wetland in China was selected to investigate the spatiotemporal patterns of groundwater heavy metals and the driving mechanism along an intertidal transect with distinct undulated topography and vegetation zonation. Along the transect, five groundwater observation wells (W1-5) were set to collect groundwater samples at three different sediment depths (0.5, 1.2, and 2.0 m) and the advective flux between groundwater and surface water were calculated during four seasonal sampling campaigns from 2019 to 2020. The results showed that the seaward W1-3 acted as the groundwater discharge area while the landward W4-5 served as the surface water recharge area. The results of single-factor contamination index showed that a potential pollution risk of Hg existed at the study sites. The distribution of other heavy metals in the mangrove groundwater exhibited a seasonal variability along the transect during the sampling campaigns. For example, the relative high concentrations of Fe, Pb, Cu, Cr, and Zn focused in the landward zones in the dry seasons (autumn and winter 2019), whereas they changed to the seaward zones in the wet seasons (summer and autumn 2020). Moreover, the intertidal aquifer can act as a sink to enrich heavy metals in winter 2019 and autumn 2020 but become a source to discharge heavy metals to the sea in summer 2020. The above migration patterns of heavy metals were ascribed to the multiple complex factors including the seawater-groundwater interactions, vegetation zonation, biogeochemical reactions, and anthropogenic activities. This study contributed to the better understanding of heavy metal behaviors in mangrove groundwater so as to improve the sustainable management of mangrove wetlands under the pressure of anthropogenic activities and climate change. [ABSTRACT FROM AUTHOR]

[Display omitted] • Seasonal sampling of heavy metals in the groundwater was conducted in a subtropical mangrove wetland. • The enrichment trend of heavy metals exhibited seasonal variations along the intertidal transect. • COVID-19-induced attenuation of anthropogenic activity reduced terrestrial input of heavy metals to the sea. • The intertidal aquifer served as a buffer zone for the transport of heavy metals to the sea. Mangrove wetlands connecting the land and sea are critical and dynamic ecosystems which act as biogeochemical reactors that influence the concentrations and distributions of heavy metals in the groundwater and adjacent seawater. In this paper, a subtropical mangrove wetland in China was selected to investigate the spatiotemporal patterns of groundwater heavy metals and the driving mechanism along an intertidal transect with distinct undulated topography and vegetation zonation. Along the transect, five groundwater observation wells (W1-5) were set to collect groundwater samples at three different sediment depths (0.5, 1.2, and 2.0 m) and the advective flux between groundwater and surface water were calculated during four seasonal sampling campaigns from 2019 to 2020. The results showed that the seaward W1-3 acted as the groundwater discharge area while the landward W4-5 served as the surface water recharge area. The results of single-factor contamination index showed that a potential pollution risk of Hg existed at the study sites. The distribution of other heavy metals in the mangrove groundwater exhibited a seasonal variability along the transect during the sampling campaigns. For example, the relative high concentrations of Fe, Pb, Cu, Cr, and Zn focused in the landward zones in the dry seasons (autumn and winter 2019), whereas they changed to the seaward zones in the wet seasons (summer and autumn 2020). Moreover, the intertidal aquifer can act as a sink to enrich heavy metals in winter 2019 and autumn 2020 but become a source to discharge heavy metals to the sea in summer 2020. The above migration patterns of heavy metals were ascribed to the multiple complex factors including the seawater-groundwater interactions, vegetation zonation, biogeochemical reactions, and anthropogenic activities. This study contributed to the better understanding of heavy metal behaviors in mangrove groundwater so as to improve the sustainable management of mangrove wetlands under the pressure of anthropogenic activities and climate change. [ABSTRACT FROM AUTHOR]