Fingerprinting Sources of the Sediments Deposited in the Riparian Zone of the Ruxi Tributary Channel of the Three Gorges Reservoir (China)

The riparian zone of the Three Gorges Reservoir serves as a critical transitional zone located between the aquatic and surrounding terrestrial environments. The periodic anti-seasonal alternation of wet and dry periods results in an intensive exchange of substance within the riparian zone. The discrimination of the sources of the sediments deposited within the riparian zone is of fundamental importance for the evaluation of the soil pollution and associated environmental impacts and for the protection of the water quality in the reservoir. In this study, a composite fingerprinting technique has been applied to apportion the sediment sources for the riparian zone with different elevations, ranging between 145—155, 155–165, and 165–175 m in a typical tributary channel. From a sediment perspective, the sediments suspended from the Yangtze mainstream represent the primary sources of the riparian deposits. From a contamination perspective, the sediment input from the Ruxi tributary channel represents an important source of pollution for the riparian environment. More effective sediment and sediment-associated contaminant control plans are needed to reduce the potential environmental problems of the riparian zone

Influence of Precipitation Characteristics and Vegetation on Runoff and Sediment: A Case on the Basin in the Three Gorges Reservoir Region

Sediment is the main carrier of pollutants in river channels. This study analyzed the distribution characteristics of precipitation, runoff, and sediment and their response characteristics in the Daning River basin. Based on daily precipitation (1979–2017), runoff (1989–2017), and sediment (1997–2017) time series, the Gini concentration index, precipitation concentration index (PCI), precipitation concentration degree (PCD), and precipitation concentration period were applied to assess the concentration characteristics of precipitation, runoff, and sediment on the daily, monthly, and seasonal scales. At each intensity level, precipitation was negatively correlated to the PCI and PCD. The normalized difference vegetation index (NDVI) values had strong negative correlations with rainy days with light precipitation (0.1–9.9 mm). The degrees of concentration were in the same order for the multiscale analysis: runoff < precipitation < sediment. Although the amount of daily precipitation of more than 25 mm displayed a significant increasing trend, suggesting an increased risk of flood and soil erosion, the significantly improved vegetation cover reduced the sediment-carrying capacity of the surface runoff, with significant decreases in the total amount and multiscale concentration degrees of sediment being observed. The results of the study provide a reference for the improvement of the potable water safety and ecological environment in the Three Gorges Reservoir region

Variation Law of Thickness Fraction of Three-Laminated Aluminum Composite Plate by Solid–Liquid–Solid and Liquid–Solid–Liquid Twin-Roll Casting

Solid–liquid–solid twin-roll casting (SLS-TRC) and liquid–solid–liquid twin-roll casting (LSL-TRC) are two processes for manufacturing three-laminated aluminum composite plates by using solid–liquid cast-rolling composite technology. In order to study the variation law of thickness fractions, a 1060/3003/1060 three-laminated aluminum composite plate was taken as the manufacturing product, and the thickness of the solid strip was used as the variable. Based on the “uactive” user subroutines of MSC.MARC software, the 2D thermomechanical coupling models of SLS-TRC and LSL-TRC were established respectively, and the thickness variation law of the solid strip under the two processes was obtained and verified by experiments. Finally, the recommended process was given according to the target thickness fraction. The results show that with an increase in the cladding thickness, the KISS point (complete freezing point of molten metal) height of the SLS-TRC process increases, the coordinated deformation position decreases relative to the KISS point, and the strain increases. In the LSL-TRC process, as the thickness of the core increases, KISS point height increases, the coordinated deformation position decreases relative to the KISS point, and the strain decreases. The formation process of the composite interface of the two processes is consistent with the N. Bay theory. Finally, through the comparison of cast-rolling forces, it was found that when manufacturing a three-laminated aluminum composite plate with a relatively small thickness fraction (the thickness fraction is less than 30%), the SLS-TRC process requires less load; when the thickness fraction of the three-laminated aluminum composite plate is large (the thickness fraction is greater than 30%), the load required for the manufacturing of the LSL-TRC process is small. The results of this research can provide practical guidance for the manufacturing of three-laminated metal matrix composite panels

¹³⁷Cs-Based Variation of Soil Erosion in Vertical Zones of a Small Catchment in Southwestern China

The study of the variability of soil erosion in mountainous areas provides the basis for soil and water conservation work and forest ecological construction in a targeted way. In this study, Liangshan Town catchment, a typical catchment in the Hengduan Mountains region, southwest China, was selected to investigate the variation of soil erosion in different vertical zones using the 137Cs tracing technique. The mean 137Cs reference inventories varied between 573.51 and 705.54 Bq/m2, with the elevation increasing from 1600 to 2600 m. The rates of soil erosion exhibited a significant variation. Under the same land cover condition, the average annual soil erosion modulus of high-elevation forest (elevation &gt; 2200 m) was 400.3 t/(km2&#183;a). However, the average annual soil erosion modulus of a low-elevation sparse forest (elevation &lt; 1600 m) was as high as 1756 t/(km2&#183;a). The average annual soil erosion modulus of the sloping farmland, mainly distributed at elevations of 1600&#8211;2200 m, was estimated to be 2771 t/(km2&#183;a). These results indicate that effective soil management measures need to be implemented on the cultivated sloping land in the future

Variation Law of Thickness Fraction of Three-Laminated Aluminum Composite Plate by Solid&ndash;Liquid&ndash;Solid and Liquid&ndash;Solid&ndash;Liquid Twin-Roll Casting

Solid&ndash;liquid&ndash;solid twin-roll casting (SLS-TRC) and liquid&ndash;solid&ndash;liquid twin-roll casting (LSL-TRC) are two processes for manufacturing three-laminated aluminum composite plates by using solid&ndash;liquid cast-rolling composite technology. In order to study the variation law of thickness fractions, a 1060/3003/1060 three-laminated aluminum composite plate was taken as the manufacturing product, and the thickness of the solid strip was used as the variable. Based on the &ldquo;uactive&rdquo; user subroutines of MSC.MARC software, the 2D thermomechanical coupling models of SLS-TRC and LSL-TRC were established respectively, and the thickness variation law of the solid strip under the two processes was obtained and verified by experiments. Finally, the recommended process was given according to the target thickness fraction. The results show that with an increase in the cladding thickness, the KISS point (complete freezing point of molten metal) height of the SLS-TRC process increases, the coordinated deformation position decreases relative to the KISS point, and the strain increases. In the LSL-TRC process, as the thickness of the core increases, KISS point height increases, the coordinated deformation position decreases relative to the KISS point, and the strain decreases. The formation process of the composite interface of the two processes is consistent with the N. Bay theory. Finally, through the comparison of cast-rolling forces, it was found that when manufacturing a three-laminated aluminum composite plate with a relatively small thickness fraction (the thickness fraction is less than 30%), the SLS-TRC process requires less load; when the thickness fraction of the three-laminated aluminum composite plate is large (the thickness fraction is greater than 30%), the load required for the manufacturing of the LSL-TRC process is small. The results of this research can provide practical guidance for the manufacturing of three-laminated metal matrix composite panels

Relationship between Precipitation Characteristics at Different Scales and Drought/Flood during the Past 40 Years in Longchuan River, Southwestern China

In this study, the temporal and spatial patterns of rainfall in the Longchuan River basin from 1977 to 2017 were analyzed, to assess the feature of precipitation. Based on the daily precipitation time series, the Lorenz curve, precipitation concentration index (PCI), precipitation concentration degree (PCD), and the precipitation concentration period (PCP) were used to evaluate the precipitation distribution characteristics. The PCI, PCD and PCP in five categories, defined by the fixed thresholds, were proposed to investigate the concentrations, and the average values indicated the higher concentrations in the higher intensities. The indices showed strong irregularity of daily and monthly precipitation distributions in this basin. The decrease in the PCD revealed an increase in the proportion of precipitation in the dry season. The rainy days of slight precipitation in the upper and lower basins with significant downward trends (−13.13 d/10 a, −7.78 d/10 a) led to longer dry spells and an increase in the risk of drought, even severe in the lower area. In the upper basin, the increase in rainfall erosivity was supported by the upward trend in the PCIw of heavy precipitation and the simple daily intensity index (SDII) of extreme precipitation. Moreover, the PCP of light precipitation, moderate precipitation, and heavy precipitation concentrated earlier at the end of July. The results of this study can provide beneficial reference information to water resource planning, reservoir operation, and agricultural production in the basin

Effects of Three Different Anticoagulants on Blood Cell Morphology, Anticoagulation, and Hematological Parameters in Turbot (Scophthalmus maximus)

Fish blood tends to coagulate due to its specialized characteristics. In general, the detection of blood physiological indices using anticoagulants reflects normal physiological status. However, the selection and application of anticoagulants have no uniform standards because of the specificity and diversity of fish species. In the present study, the effects of three different anticoagulants (sodium heparin, K2EDTA, and sodium citrate) were investigated on coagulation, blood cell type, hematological parameters (white blood cells, red blood cells, hematocrit, and hemoglobin), and plasma cortisol and glucose contents in turbot during acute hypoxic stress. The choice of anticoagulants may result in significant differences in turbot blood physiology and chemistry. To supply technological support in turbot hematological research and best-practice aquaculture, this study compared the effects of three common anticoagulants between normal dissolved oxygen and acute hypoxic states. The recirculating aquaculture system is the main culture model for turbot; water temperature and dissolved oxygen levels are important environmental factors, especially in high-density industrial systems. Sufficient oxygen is key to maintaining normal metabolism in turbot. Experimental procedures were designed for control and treatment groups, each group had three parallels, and 54 turbots were studied in all. In the control group, 200 mg/L MS-222 was used to anesthetize a specimen before collecting 5 mL of blood from the caudal vein; the blood was transferred through a needle and vacuum tubes containing three different anticoagulants, then the vacuum tubes were stored for evaluation after 6 h and 12 h. In the treatment group, nitrogen gas was used to rapidly reduce the concentration of dissolved oxygen in the container to (1.2±0.3) mg/L (measured with a dissolved oxygen meter), after which the same procedure of anesthesia and blood collection was conducted. For blood cell type and morphology studies, the Giemsa staining method was used to make blood smears. The original solution of Giemsa was diluted before use. The slide was sterilized before a drop of blood was placed on one side of the slide; one edge of a cover glass was placed in contact with the drop of blood and pushed to the opposite side of the slide at a constant velocity; the slide was then fixed with methanol for 10~15 min and stained for 15~30 min. The smears were washed and dried after staining. Finally, the stained smears were observed under a Leica microscope to determine blood cell morphology, and images were taken. Blood samples were divided into two parts for detecting physiological and biochemical indices: one was centrifuged at 3500 r/min for 10 min, and the supernatant was stored at –80℃ for the detection of plasma glucose and cortisol content using commercial kits. The residual blood samples were stored in a refrigerator at 4℃ for the detection of physiological indices using an automatic blood cell analyzer. The anticoagulant effect of K2EDTA was most effective under a normal dissolved oxygen state, and the anticoagulant effect of K2EDTA and heparin sodium were most effective after 6 h and 12 h of exposure to acute hypoxia stress, respectively. In addition to coagulation, blood cell morphology showed that binucleate cells occurred through sodium heparin, eosinophils, and basophils through sodium citrate and basophils through K2EDTA in the control. Three nucleus abnormality types were identified in the smears: micronucleus cells, binucleate cells, and erythroplastids. Binucleate cells were found using sodium heparin in the control group. In addition, binucleate cells were observed under three different anticoagulants in the treatment group, and micronucleus cells and erythroplastids were observed in the treatment group. The hematological index showed that the number of white blood cells was significantly increased by treatment with three anticoagulants during acute hypoxic stress (P < 0.05), and the number of red blood cells and hemoglobin content was significantly increased by treatment with K2EDTA and sodium heparin (P < 0.05). However, they were significantly reduced after treatment with sodium citrate. In addition, the plasma glucose and cortisol content were significantly increased when subjected to acute hypoxic stress, but the content of sodium heparin was significantly lower than that of both sodium citrate and K2EDTA. In summary, K2EDTA showed less blood coagulation than other anticoagulants, sodium heparin caused binucleate cells and decreased plasma glucose and cortisol, and sodium citrate affected the number of red blood cells and hemoglobin content. K2EDTA is the more promising anticoagulant compared to sodium heparin and sodium citrate for blood analysis of turbot and promotes the precision of turbot hematological studies under acute hypoxic conditions