Compound erosion effect of snowmelt, wind, and rainfall on sloping farmlands of Chinese typical Mollisol region.

Research on the processes and mechanisms of compound soil erosion by multiple forces can provide scientific guidance for precisely controlling cropland soil erosion. Based on the seasonal alternation of freezing-thawing, snowmelt, wind, and rainfall erosion forces on sloping farmlands under natural conditions from November to next October of each year, we used a set of indoor simulation experiments of multi-force superimpositions to analyze the compound soil erosion processes of snowmelt (1 and 2 L·min-1), wind (12 m·s-1), and rainfall (100 mm·h-1). We further discussed the erosion effects of multi-force superimpositions. The results showed that, under single snowmelt erosion, an increase in snowmelt flow had a greater effect on sloping snowmelt erosion intensity than that of sloping runoff rate. When sloping snowmelt flow increased from 1 L·min-1 to 2 L·min-1, sloping runoff rate and erosion intensity increased by 2.7 and 4.0 times, respectively. Under snowmelt-wind superimposition erosion, previous sloping snowmelt erosion inhibited late wind erosion occurrence. As sloping snowmelt flow increased from 1 L·min-1 to 2 L·min-1, the inhibiting action subsequently increased and wind erosion intensity caused by previous snowmelt reduced by more than 50%. Both wind erosion and snowmelt-wind superimposed erosion intensified late rainfall erosion. The early wind erosion increased rainfall erosion by 24.5%. The snowmelt-wind superimposed effect increased the later slope rainfall erosion by 132.8% and 465.4% under 1 and 2 L·min-1 snowmelt runoff rates, respectively. The compound soil erosion amount driven by multiple force superimposition was not the sum of the corresponding erosion amount caused by single erosion force, with promoting or inhibiting effects of erosion force superimposition. The erosion effect of snowmelt-wind superposition was negative, but that of wind-rainfall superposition and snowmelt-wind-rainfall superpositions were positive.

Amount and characteristics of microplastic and organic matter in wind-blown sediment at different heights within the aeolian sand saltation layer.

Soils of croplands especially where plastic film mulch is commonly applied, are normally contaminated by Microplastics (MPs). Microplastics can threaten air quality, food and water health, as well as human health by wind erosion processes. In this research, we investigated MPs collected in four wind erosion events at sampling heights between 0 and 60 cm in typical semiarid farmlands in northern China that employ plastic film mulch. Height distribution and enrichment heights of the MPs were measured. The results revealed that the average amounts of MPs for 0-20 cm, 20-40 cm and 40-60 cm sampling heights were 868.71 ± 249.21, 799.87 ± 271.25, 1102.54 ± 317.44 particles kg-1. The average enrichment ratios of MPs for the different heights were 0.89 ± 0.54, 0.85 ± 0.56, 1.15 ± 0.73. Height distribution of MPs was combined affected by shape (fiber and non-fiber) and size of MPs, wind speed and soil aggregate stability. The amount of fibers approximately <4 mm in size and non-fibers <2 mm in size increased with sampling height, while both shapes of larger MPs than these two sizes was almost independent of the sampling height. Enrichment ratios of microfibers were positively related to wind speed but negatively related to soil aggregate stability at each sampling height. The results revealed that although MPs have similar density to organic matter (OM), the MPs' amount and enrichment were independent of height but the OM content and enrichment ratios increased with height. These results suggested that more attention should be paid to the exploration of the influence of higher sampling heights (>60 cm) on the distribution of MPs in the future and the MPs characteristics for different sampling heights require carefully parameterization in detailed models of atmospheric MPs transport by wind erosion.

Association Between Family Structure and Anxiety Disorder Among Pre-schoolers: A Cross-Sectional Study in Urban Chongqing, China.

Objective: This study explores the current situation of anxiety disorder of pre-schoolers and assesses the association between family structure and anxiety disorder (AD) among pre-schoolers in Chongqing, China. Methods: This is a cross-sectional study of 499 main fosterers of children aged 3-6 years who completed the 28-item Chinese version of the Spence Pre-school Anxiety Scale (PAS). Multinomial logistic regression with three models was used to assess the association of the family structure with the different AD. Results: The prevalence of AD was 31.46%, whose score of PAS were more than 48. Among the five different PAS sub-scales, the prevalence of obsessive-compulsive disorder (OCD) was the highest (50.10%), followed by separation anxiety disorder (SAD, 39.28%), fear of physical harm (FPH, 37.68%), generalized anxiety disorder (GAD, 33.47%), and social phobia (SP, 25.85%). Pre-schoolers from inter-generational families were more probably have AD than those from nuclear families (OR = 3.73, p < 0.05). The participants from inter-generational families were more likely to have SAD (OR = 3.39, p < 0.05), FPM (OR = 2.80, p < 0.05), or OCD (OR = 2.40, p < 0.05), in comparison with participants from other family structures. Conclusion: Anxiety disorder among pre-schoolers aged 3-6 in Chongqing is widespread. Pre-schoolers from inter-generational families were more probably have AD, SAD, FPM, and OR and pre-schoolers from stem families may be less likely to have SAD compared with those from nuclear families. Relieving the anxiety of pre-schoolers may be possible with additional interventional efforts in inter-generational families.

Knowledge of Child Health and Affecting Factors Among Preschool Teachers: A Cross-Sectional Study in Chongqing, China.

AIM: This research aims to explore the health knowledge mastery of preschool teachers in Chongqing. METHODS: A cross-sectional questionnaire survey of preschool teachers in Chongqing was conducted by random sampling. A total of 399 preschool teachers were included in this research. Multiple linear regression analysis was conducted to explore the influencing factors on preschool teachers' mastery of preschool child health knowledge. RESULTS: This research found that the average score of preschool teacher's knowledge of preschool children was only 34.01±0.78, and the accuracy of the knowledge points of continuous short-distance eye use time was the lowest, at less than 5%. The conducting of eye exercises by the kindergarten and the scores of preschool teachers were negatively correlated (ß=-0.257, p<0.001); the score of health knowledge of preschool teachers of the kindergarten whose screen time met the standard was lower (ß=-0.113, p=0.017); whether the time and frequency for outdoor activities of the kindergarten met the standards and the health knowledge score of preschool teachers was positively correlated (ß=0.130, p<0.001 vs ß=0.163, p<0.001). Male preschool teachers and teachers overweight according to BMI had higher scores for preschool health knowledge (ß=-0.114, p=0.016 vs ß=0.099, p=0.034). CONCLUSION: Preschool teachers in Chongqing had a poor grasp of knowledge regarding preschool children's health, and in particular, knowledge of children's exercise and eye use. Educational background and work experience may no longer indicate preparedness for teaching these topics, and suggests that supportive measures can also be directly provided at the kindergarten level in the future to increase the health knowledge of preschool teachers.

[Effects of "Grain for Green" program and coal mining on sediment production in a typical small watershed of Yushenfu Mining Region, Northwest China].

Soil erosion in the ecologically fragile zone is severely affected by the intensified coal mining activities in the Yushenfu Mining Region of the Loess Plateau. Soil erosion controlling projects such as the "Grain for Green" program are continuously implemented by the government, which has effectively mitigated or even controlled soil erosion. Coal mining results in new environmental problems, which has changed the erosion characteristics and sediment transport in watersheds. In this study, we identified the sediment source trapped behind the check dam using a composite fingerprinting approach and clarified the impact of "Grain for Green" program and coal mining on variation of the amount and sources of sediment during two decades, in a representative check-dam which controlled the watershed of Laoyeman. The two decades were divided into two stages, i.e. an earlier decade (1990-1999) and a later decade (2000-2010) with respect to the implement of the "Grain for Green" program in the flood couplets sequence established during the running of the dam. The annual average thickness of flood couplets during 2000-2010 decreased from (42.7±29.9) cm to (16.6±13.7) cm during 1990-1999, and the annual sediment deposition per unit area (square meter) at the sampling site reduced from 579.9 kg·m-2 to 245.8 kg·m-2. The main source of sediment was gully wall (averaged 79.2%±10.1%) during the study period. However, compared with sediment sources during 1990-1999, the contribution of sediment from slope during 2000-2010, which was greatly affected by the "Grain for Green" program, showed an increasing trend (average annual contribution increased by 7.4%). According to the coaling mining and the variation of rainfall erosivity, our results indicated that under the combined effects of the "Grain for Green" program and decreases of rainfall erosivity, the intensity of sediment production in the watershed was substantially decreased. Coal mining had important impacts on sediment contribution from the slope, and obviously affected soil erosion controlling effects of the "Grain for Green" program. It is obvious that coal mining has increased the risk of erosion and sediment production on the slope, and that soil erosion control on the slope should focus on areas affected by coal mining.

Parental Influence in Forming Preschool Children's Eating Behaviors-A Cross-Sectional Survey in Chongqing, China.

Children's eating habits are closely related to their health problems and the outlook for children's nutritional statuses appears poor. A cross-sectional survey was conducted among parents of preschool children from December 2018 to January 2019. Sixteen representative kindergartens in 6 districts of Chongqing, China, were included in the study. We took 2200 samples and collected information by questionnaire and after screening, 1781 questionnaires were valid and finally included in the data analysis (n = 1781). Ordinal logistic regression analysis found that age, fathers' education level, forced diet and perception of children's body shape were factors associated with children's eating behaviors (ordered logistic regression/three-level eating behavior; odds ratios p < 0.05). 80.24% of preschool children may have unhealthy eating behavior in this survey and 80.35% of parents had forced their children to eat. Eating behaviors of preschool children in Chongqing are closely related to family factors. This study provides important insight for parents and health care workers in China to improve preschool-aged children's nutritional behaviors. Intervention programs should focus on parents with low income, low education levels, coercive dietary behaviors and deviated body shape perceptions to reduce children's eating behavioral problems.

Impacts of biochar application rates and particle sizes on runoff and soil loss in small cultivated loess plots under simulated rainfall.

Increasing literature suggests that biochar can be used to improve soil fertility and subsequently benefit crop yield. However, the effects of biochar application rates and particle sizes on soil erosion processes have yet to be fully identified. The objective of the present study was to evaluate the influence of biochar with different application rates and particle sizes on soil erosion. Addition of biochar to loess generally increased the mean time to runoff by 19.47% relative to the control. The time to runoff decreased with an increase in the biochar application rates and fluctuated with a decrease in biochar particle sizes. The combined 1% and <0.25 mm biochar treatment yielded the longest time to runoff (2.97 min) and the lowest runoff (36.23 kg m-2 h-1) and soil loss (1.33 kg m-2 min-1). Biochar addition decreased the total runoff volume by 12.21% and generally inhibited soil loss under lower application rates (1% and 3%) while promoting soil loss under higher application rates (5% and 7%). With a decrease in biochar particle size, total runoff volume increased under the 5% and 7% biochar, but no uniform trend was observed under the 1% and 3% biochar treatments. The total soil loss increased with increasing biochar application rates, whereas a negative trend was observed with decreasing biochar particle sizes. The contribution of biochar application rates to runoff and soil loss rates was distinctly greater than the biochar particle sizes. Additionally, biochar addition could increase >2 mm water-stable soil aggregates and saturated hydraulic conductivity (Ksat) in this study. We inferred that the positive effects on soil and water loss were potentially due to the improvement in >2 mm water-stable soil aggregates and Ksat. The results implied that soil-biochar additions could be a potential measure for conserving soil and water in the Loess Plateau.

Beryllium-7 in vegetation, soil, sediment and runoff on the northern Loess Plateau.

Beryllium-7 (7Be), as a potentially powerful tracer, was widely used to document soil redistribution and identify sediment sources in recent decades, but the quantity and distribution of 7Be in vegetation, soil, sediment and runoff on the Loess Plateau have not been fully described. In this study, we measured 7Be in vegetation, soil, sediment and runoff on the northern Loess Plateau of China and analyzed its variations during the rainy season to assess the potential of the 7Be method for documenting soil redistribution and identifying sediment sources in a wide range of environments. The results indicated that vegetation, soil, and sediment samples showed higher levels and larger variations of 7Be activities during the rainy season. The drying plants showed 7Be mass activity that was more than three times higher than that of living and semi-decomposed plants. 7Be mass activity in plants and sediment was much higher than in the soil. 7Be activity in runoff water with a few submicron suspended particles varied slightly and was far lower than in plant, soil and sediment samples. The cumulative precipitation generally determined 7Be inventory held by plants and soil. An inverse relationship was found between the 7Be mass activity in sediment and the sediment amount. Globally, approximate 30% of the total 7Be was held by plants in both the herbaceous and subshrub plots. Approximate 10% of the total 7Be was lost with sediment from the bare plot. A very small proportion of 7Be (1.18%-3.20%) was lost with runoff, and the vast majority of 7Be was retained in the slope soil at the end of rainy season. Vegetation cover and soil erosion significantly affected the spatial distribution and variations of the 7Be inventory in soil, providing a necessary condition for the development of a 7Be method to document soil erosion on slopes with vegetation.

Beryllium-7 measurements of wind erosion on sloping fields in the wind-water erosion crisscross region on the Chinese Loess Plateau.

Soil erosion is complex in the wind-water erosion crisscross region of the Chinese Loess Plateau, as interleaving of wind and water erosion occurs on both temporal and spatial scales. It is difficult to distinguish wind erosion from the total erosion in previous studies due to the untraceable of aeolian particles and the limitation of feasible methods and techniques. This study used beryllium-7 measurements to study wind erosion in the wind-water erosion crisscross region on the Chinese Loess Plateau arms to delineate wind erosion distribution, to analyze its implication to erosive winds and surface microrelief, and to determine correlations between erosion rates and slope gradients. Results obtained using beryllium-7 measurements based on observation plots were verified with saltating particle collection method, and were also verified on a field scale. Results indicated that the effective resultant erosion wind was from northward, which was proved by the eight-directional distributed saltating particles. The microrelief of the ground surface contributed to the formation of high or low erosion centers. Wind erosion rates increased with a linear (R2≥0.95) or exponential (R2≥0.83) fitting increase in the slope gradients as reported in previous studies. Compared to wind erosion on field scale, both the plots and fields exhibited similar distribution patterns in wind erosion isolines. We also determined that the wind erosion rate for two fields estimated, based on equations developed from plot scale was acceptable. This study validates the feasibility of beryllium-7 measurements for soil-wind erosion field experiments and the potential to expand this approach to real field conditions.

Sediment transport capacity of concentrated flows on steep loessial slope with erodible beds.

Previous research on sediment transport capacity has been inadequate and incomplete in describing the detachment and transport process of concentrated flows on slope farmlands during rill development. An indoor concentrated flow scouring experiment was carried out on steep loessial soil slope with erodible bed to investigate the sediment transport capacity under different flow rates and slope gradients. The results indicated that the sediment transport capacity increases with increasing flow rate and slope gradient, and these relationships can be described by power functions and exponential functions, respectively. Multivariate, nonlinear regression analysis showed that sediment transport capacity was more sensitive to slope gradient than to flow rate, and it was more sensitive to unit discharge per unit width than to slope gradient for sediment transport capacity in this study. When similar soil was used, the results were similar to those of previous research conducted under both erodible and non-erodible bed conditions. However, the equation derived from previous research under non-erodible bed conditions with for river bed sand tends to overestimate sediment transport capacity in our experiment.