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To investigate an appropriate wind load design for buildings considering dynamic air density changes, classical extreme value and copula theories were utilized. Using wind speed, air temperature, and air pressure data from 123 meteorological stations in Shandong Province from 2004 to 2017, a joint probability distribution model was established for extreme wind speed and air density. The basic wind pressure was calculated for various conditional return periods. The results indicated that the Gumbel and Gaussian mixture model distributions performed well in extreme wind speed and air density fitting, respectively. The joint extreme wind speed and air density distribution exhibited a distinct bimodal pattern. The higher the wind speed was, the greater the air density for the same return conditional period. For the 10-year return period, the air density surpassed the standard air density, exceeding 1.30 kg/m3. The basic wind pressures under the different conditional return periods were more than 10% greater than those calculated from standard codes. Applying the air density based on the conditional return period in engineering design could enhance structural safety regionally. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is an indispensable element for organisms but the primary source of P—mineral phosphate resources—are non-renewable. Agricultural production has a high demand for fossil phosphate resources, but the resulting phosphate-rich residues are lack of management. This leads to rapid reserves depletion and severe phosphate pollution risks. One sustainable way is to reuse the phosphate dispersed in various residues such as sewage sludge and livestock manure. Diverse techniques have emerged to recover phosphate from wastes to close the phosphate cycle. While it is a global issue, the regional situations regarding potential phosphate scarcity and its management differ strongly. China is rich in phosphate resources, but over-exploitation has greatly increased the risk of phosphate rocks depletion, while in Germany the P resources depend on imports, but there is commitment to keep a balance between import and utilization. This had led to great differences in the way the two countries deal with the “re-use” of phosphate in waste. China is now in a transition phase from the simple terminal pollution control to “waste” reuse and nutrient resources recycling. One sign of this tendency is the mandatory garbage classification and preparation for further processing and recycling. This was first implemented in Shanghai in 2019, whereas Germany has been following the legal framework for waste management since the 19th century. There are a series of laws to control the nutrient loss from municipal and agricultural activities, as for instance with sewage sludge ordinance and fertilizer legislation. Many of these laws have been newly revised recently. Sewage sludge cannot be directly utilized on farmland as organic fertilizer any more. Alternatively, phosphate and other nutrients should be recovered from sewage sludge. Advanced phosphate recovery technologies and related nutrient recycling schemes are proceeding. This review summarizes the current situation of phosphate-containing residues management and phosphate reuse in China and Germany. The state legislation and policies, which would affect the phosphate recycling concept are presented as well. As there are various kinds of phosphate-containing residues, different phosphate recovery technologies can be applied. Those technologies are discussed from their mechanism and suitability.

As a frequent hazard, tropical cyclones have a great impact on the social and economic development of China, which is close to the origin of tropical cyclones in the western Pacific Ocean. The primary objective of this study was to construct a comprehensive risk assessment model for tropical cyclone hazards based on natural influencing factors, informing recommendations for hazard prevention and mitigation in affected regions. This research focused on tropical cyclones that made landfall in mainland China and Hainan from 1949 to 2023, utilizing hazard risk theory and classical extreme value theory. The wind speed and rainfall data during the peak cyclone periods (June to October) from 1997 to 2021 gathered from various meteorological stations, as well as altitude and vegetation cover data, were examined. Hierarchical analysis and ArcGIS spatial analysis methods were employed to study the characteristics of the spatiotemporal distribution of landfalling tropical cyclones and the comprehensive risk of tropical cyclone hazards, and the regions of China were delineated according to these methods. The results showed that, during the period from 1949 to 2023, the overall number of landfalling tropical cyclones decreased in a fluctuating manner, while the intensity of the cyclones increased. Furthermore, severe typhoons tended to occur more frequently in the summer than autumn with time, intensifying the challenge to resist short-term hazards. Moreover, the hazard-causing factors in areas affected by tropical cyclones displayed an increasing trend from north to south and from west to east. In detail, the regions sensitive to natural hazards were primarily located in the central part of Liaoning province, Tianjin, central and eastern Hebei province, Shandong province, eastern Henan province, central and northern Anhui province, Jiangsu province, and Shanghai, which are characterized by flat terrain and relatively low vegetation cover. Overall, the comprehensive risk of tropical cyclone hazards showed a geographical distribution that decreases from south to north and from east to west, with coastal cities in provinces such as Hainan, Guangdong, Guangxi, Fujian, and Zhejiang—including Haikou, Zhanjiang, Xiamen, Beihai, and Taizhou—exhibiting the highest levels of risk. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new regional wind erosion events assessment method based on RF model was developed. • Integration of probabilistic statistical thoughts into wind erosion process studies. • Identification of the spatial distribution characteristics of threshold wind velocity. • Occurrence probability of wind erosion is assessed on a high-spatial-resolution scale. • 19.41 % of the study area has annual cumulative wind erosion duration near 1.5 months. The importance of air density variations in aeolian sand movement investigations is currently attracting widespread consideration. For this purpose, the spatial distribution characteristics of threshold wind velocity under the influence of air density are determined. To better understand the occurrence conditions of wind erosion events at different spatiotemporal scales, the present paper regards the air density metric as a bridge linking wind speed distribution and threshold wind velocity, reveals the coupling relationship between air density and wind speed by introducing the statistical distribution function method of probabilistic statistical thoughts, and accomplishes the scaling up of wind speed distribution parameters according to the random forest algorithm, achieving a comprehensive evaluation of the regional overall level of wind erosion events. The results demonstrate that the mean threshold wind velocity value in the study area is 4.29 m/s, displaying a decreasing pattern with higher values in the west and lower values in the east. The mean occurrence probability of the wind erosion value is 7.92 %, with regions exceeding 12 % basically located in the central and eastern parts of the Hunshandake Sandy Land, which means that the total annual cumulative time of wind erosion in these areas is expected to approach 1.5 months. This study can contribute to the development of a systematic assessment framework of wind erosion potential risks at the regional scale. It will provide crucial information and new insights for wind erosion process research, thereby offering a theoretical basis and technical reference for a full understanding of land desertification evolution patterns. [ABSTRACT FROM AUTHOR]