Effects of Air Pollutants on Summer Precipitation in Different Regions of Beijing

Many studies have shown that air pollutants have complex impacts on urban precipitation. Meteorological weather station and satellite Aerosol Optical Depth (AOD) product data from the last 20 years, combined with simulation results from the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem), this paper focuses on the effects of air pollutants on summer precipitation in different regions of Beijing. These results showed that air pollution intensity during the summer affected the precipitation contribution rate (PCR) of plains and mountainous regions in the Beijing area, especially in the plains. Over the past 20 years, plains PCR increased by ~10% when the AOD augmented by 0.15, whereas it decreased with lower pollution levels. In contrast, PCR in mountainous areas decreased with higher pollution levels and increased with lower pollution levels. Our analysis from model results indicated that aerosol increases reduce the effective particle size of cloud droplets and raindrops. Smaller cloud raindrops more readily transport to high air layers and participate in the generation of ice-phase substances in the clouds, increasing the total amount of cloud water in the air in a certain time, which ultimately enhanced precipitation intensity on the plains. The removal of pollutants caused by increased precipitation in the plains decreased rainfall levels in mountainous areas.

Impact of Irrigation Erosion on the Agrochemical Properties of Mountain-brown Soils and the Productivity of Cereals and Legumes

The cultivation of perennial grasses in mountainous areas protects the slopes from erosion and provides animals with good food. According to the results of the studies, it was determined that the restoration of fertility and the ecological balance of erosional lands and the implementation of soil and agrotechnical measures is of great importance for increasing yields. Thanks to the application of these measures, as a result of the improvement of the water-physical properties of the affected lands, runoff of surface waters is prevented. Perennial grasses accumulate the nitrogen atmosphere of legumes, enrich the soil with organic substances, accelerate the formation of a water-resistant granular-fuel structure and improve its water-physical properties, which in turn contributes to the rapid assimilation of minerals.

Impact of Surface Improvement Measures on Low-yielding Summer Pastures on Pasture Productivity and Forage Quality

Cultivation of soil on the slopes of mountainous areas leads to a decrease in organic matter and nutrients in the soil and severe soil erosion. Grazing is one of the main reasons for the degradation of pastures and natural landscape, which increases the sensitivity of the soil to erosion. Soil erosion, in turn, pollutes water by increasing its turbidity and sometimes causes atrophy due to leakage of phosphorus and nitrogen. An average of 30.6 quintals of green mass or 7.8 quintals of dry grass per hectare was produced in the variant of grass seed sowing (without fertilizer), compared to the control variant, in the variant of grass seed sowing + N60P60K40 this indicator averaged 39.9 centners/ha of green mass. or more than 15.0%, resulting in the production of 10.0 quintals of dry or 14.7% more dry grass. Experimental field studies to improve pastures have shown that the fodder produced in each of the tested variants; green mass and dry grass supply and their nutritional value were higher than control.

Climate, CO2, and Anthropogenic Drivers of Accelerated Vegetation Greening in the Haihe River Basin

Vegetation regulates the exchange of terrestrial carbon and water fluxes and connects the biosphere, hydrosphere, and atmosphere. Over the last four decades, vegetation greening has been observed worldwide using satellite technology. China has also experienced a notably widespread greening trend. However, the responsiveness of vegetation dynamics to elevated CO2 concentration, climate change, and human activities remains unclear. In this study, we attempted to explore the impact of natural (precipitation, air temperature), biogeochemical (CO2), and anthropogenic drivers (nighttime light, afforestation area) on changes in vegetation greenness in the Haihe River Basin (HRB) during 2002–2018 at the county-level. We further determined the major factors affecting the variation in satellite-derived normalized difference vegetation index (NDVI) from moderate resolution imaging spectroradiometer (MODIS) for each county. The results indicated that over 85% of the counties had a significantly increased NDVI trend, and the average linear trend of annual NDVI across the study region was 0.0037 per year. The largest contributor to the NDVI trend was CO2 (mean contribution 45%), followed by human activities (mean contribution of 27%). Additionally, afforestation was a pronounced driving force for NDVI changes in mountainous areas, resulting from ecosystem restoration efforts. Our findings emphasize the crucial role of CO2 fertilization in vegetation cover change, while considering CO2 concentration, climate change, and human activities, and shed light on the significant influences of afforestation programs on water resources, especially in mountainous areas.

Extreme wind speed prediction in mountainous area with mixed wind climates

In addition to common synoptic wind system, the mountainous terrain forms a local thermally driven wind system, which makes the mountain wind system have strong terrain dependence. Therefore, in order to estimate the reliable design wind speeds for structural safety, the samples for extreme wind speeds for certain return periods at mountainous areas can only come from field measurements at construction site. However, wind speeds measuring duration is usually short in real practice. This work proposes a novel method for calculating extreme wind speeds in mountainous areas by using short-term field measurement data and long-term nearby meteorological observatory data. Extreme wind speeds in mountainous area are affected by mixed climates composed by local-scale wind and large scale synoptic wind. The local winds can be recorded at construction site with short observatory time, while the extreme wind speeds samples from synoptic wind climate from nearby meteorological station with long observatory time is extracted for data augmentation. The bridge construction site at Hengduan Mountains in southwestern China is taken as an example in this study. A 10-month dataset of field measurement wind speeds is recorded at this location. This study firstly provides a new method to extract wind speed time series of windstorms. Based on the different windstorm features, the local and synoptic winds are separated. Next, the synoptic wind speeds from nearby meteorological stations are converted and combined with local winds to derive the extreme wind speeds probability distribution function. The calculation results shows that the extreme wind speed in the short return period is controlled by the local wind system, and the long-period extreme wind speed is determined by the synoptic wind system in the mountain area.

Split delivery scheme for vehicle supported UAV

The traditional demand split logistics distribution schemes are mainly based on vehicle distribution. In recent years, with the rapid development of civil UAVs, the use of UAVs for distribution will be more efficient and economical in some specific conditions. In this paper, through the analysis of the advantages of UAV distribution, we simulate the demands and distribution schemes in real scene, especially in remote mountainous areas. And then, we propose to define a demand-splitting distribution scheme of vehicle-supported UAV, which ensures the customer point will be satisfy demand when the loading capacity of the UAV is exceeded. This scheme aims to provides a realizable distribution scheme for the customers point in mountainous areas with large demand.

Aralia armata roots: Extraction, isolation and molluscicidal activity against golden apple snails, Pomacea canaliculata

Aralia armata is one of the common herb species in mountainous areas, especially in the northern mountainous areas of Vietnam, which has potential in pharmaceutical and agricultural industries. Herein, we report that an oleanolic acid saponin named pseudogisenoside RT1 methyl ester (A) was isolated from the roots of the species Aralia armata. The fractionated extracts of dichloromethane, ethyl acetate, water and compound A were investigated for their molluscicidal effects, specifically on Pomacea canaliculata. The tests showed that the extracts and compound A from A. armata roots had good activity against P. canaliculata snail. In particular, compound A had a Lethal concentration of 50 (LC50) value of 16.443 µg/mL.