Recent Jishishan earthquake ripple hazard provides a new explanation for the destruction of the prehistoric Lajia Settlement 4000a B.P.

The Jishishan Ms 6.2 earthquake occurred at 23:59 on December 18, 2023 in Gansu Province, China. We conducted a field survey to assess the hazards and damages caused by the earthquake and its associated geo-activities. Subsequently, we organized a seminar to discuss the possible causes of the destruction of a prehistoric site-Lajia Settlement-dated back to four thousand years B.P. and located only several kilometers away from the epicenter of the Jishishan earthquake. The Jishishan earthquake was unique for its hazard and disaster process, which featured ground shaking and a series of complex geological and geomorphological activities: sediment and soil spray piles, liquefaction, collapse, landslide, and mudflow along water channels. We define this phenomenon as the Jishishan earthquake ripple hazard (JERH). The most recent evidence from the JERH suggests that a prehistoric earthquake similar to the JERH, instead of riverine floods or earthquake-induced landslide dam outburst flood, as previously hypothesized, destroyed the Lajia Settlement.

Vulnerability to typhoons: A comparison of consequence and driving factors between Typhoon Hato (2017) and Typhoon Mangkhut (2018).

Typhoon disasters have caused casualties, property loss, and other negative impacts to social and economic development. Vulnerability is an important component of typhoon risk. However, little is known about the contributions of vulnerability factors and their interaction effects on typhoon-induced losses at a fine scale. Focusing on the vulnerability measures of Typhoon Hato in 2017 and Typhoon Mangkhut in 2018, this study aims to quantify the contribution and interactive effects of physical and socioeconomic factors on vulnerability based on the GeoDetector method and determine the factors that account for most of the change in vulnerability. The results show that from Typhoon Hato in 2017 to Typhoon Mangkhut in 2018, the vulnerability of the economy and houses decrease on average. Rain intensity and wind intensity are the dominant factors of disaster loss for Typhoon Hato and Typhoon Mangkhut, respectively. Vegetation cover and landform explain vulnerability better than average slope in most instances. For different loss types, the dominant socioeconomic vulnerability factor is different. For both typhoons, emergency transfer has a higher determining power (q) ranking for the population vulnerability, while the percentage of the GDP made up of primary industry have higher q ranking for economic vulnerability. The dominant interaction effects between two vulnerability factors differ depending on the typhoon and loss type but show a nonlinear enhancement effect in most cases. Moreover, changes in the maximum 4-hour accumulated rainfall account for most of the change in vulnerability between Hato and Mangkhut. Overall, the results can be conducive to understanding the complexity of vulnerability to typhoons and provide a reference for possible indicators for vulnerability assessment models, and determining the reasons for changes in vulnerability can be constructive to the formulation of specific policies for disaster prevention and mitigation.

Deposited atmospheric dust as influenced by anthropogenic emissions in northern China.

Atmospheric particulate matter (PM) from multinatural and anthropogenic sources poses serious risk to human health and contaminates soil and water resources as it settles back to ground environment and ecosystem. In this study, dust deposition flux (DDF), pollution load index (PLI) of heavy metals, enrichment factor (EF), and settling flux (SF) of eighteen chemical elements were investigated in comparison with crustal composition to assess the influence of anthropogenic emission on PM in major northern Chinese cities. The annual DDF in Lanzhou, Huhhot, Beijing, Zhengzhou, and Harbin was 134.7, 240.6, 103.7, 124.7, and 196.7 g m-2, respectively. The annual EF of Zn in Harbin, Cd in Lanzhou, and Cd in Beijing was 736.4, 248.6, and 166.3, respectively. Most of the inspected elements were enriched during winter in Lanzhou. Annual PLI showed that deposited dust in Beijing had the highest concentration of heavy metals. Seasonal PLI exhibited obvious changes in different cities. The annual SF of crustal elements was 1-5 orders higher than that of heavy metals. The highest annual SF of elements was identified mainly in Lanzhou and Huhhot. Sulfur, cadmium, copper, lead, and zinc in the dustfall of most urban areas were from human activities. Fossil fuel burning, metal smelting, mining, construction, and vehicle exhaust are the major sources of enriched elements in dustfall in urban areas of northern China. Toxic pollutants with dustfall are widespread and persistent, which deserves public concern in future sustainable development.

[Physico-chemical characteristics of ambient particles settling upon leaf surface of six conifers in Beijing].

The study on the density of ambient particles settling upon the leaf surface of six conifers in Beijing, the micro-configurations of the leaf surface, and the mineral and element compositions of the particles showed that at the same sites and for the same tree species, the density of the particles settling upon leaf surface increased with increasing ambient pollution, but for various tree species, it differed significantly, with the sequence of Sabina chinensis and Platycladus orientalis > Cedrus deodara and Pinus bungeana > P. tabulaeformis and Picea koraiensis. Due to the effects of road dust, low height leaf had a larger density of particles. The density of the particles was smaller in summer than in winter because of the rainfall and new leaf growth. The larger the roughness of leaf surface, the larger density of the particles was. In the particles, the overall content of SiO2, CaCO3, CaMg(CO3,), NaCl, 2CaSO4 . H2O, CaSO4 . 2H2O and Fe2O3 was about 10%-30%, and the main minerals were montmorillonite, illite, kaolinite and feldspar. The total content of 21 test elements in the particles reached 16%-37%, among which, Ca, Al, Fe, Mg, K, Na and S occupied 97% or more, while the others were very few and less affected by sampling sites and tree species.

[Atmospheric particle-retaining capability of eleven garden plant species in Beijing].

With eleven garden plant species in Beijing as test materials, this paper determined the adhesion density of atmospheric particles on leaf surface, observed the micro-configurations of leaf epidermis, and measured the particle size distribution of the particles. The results showed that the particles were mainly adhered on upside leaf surface, and the adsorbed amount was about six times higher than that on underside leaf surface. The particle-retaining capability of the micro-configurations of leaf epidermis was decreased in the order of groove> vein + cell > cell > strip protuberance. The capability of particle-retaining was higher when the micro-configurations were denser and the fall between them was larger. The mean value and the mean percentages of PM2.5 and PM10 on upside leaf surface were 66.7% and 98.3%, while those on underside leaf surfaces were 43.4% and 92.9%, respectively.

Physicochemical characteristics of ambient particles settling upon leaf surfaces of urban plants in Beijing.

Particulate pollution is a serious health problem throughout the world, exacerbating a wide range of respiratory and vascular illnesses in urban areas. Urban plants play an important role in reducing particulate pollution. Physicochemical characteristics of ambient particles settling upon leaf surfaces of eleven roadside plants at four sites of Beijing were studies. Results showed that density of particles on the leaf surfaces greatly varied with plant species and traffic condition. Fraxinus chinensis, Sophora japonica, A ilanthus altissima, Syringa oblata and Prunus persica had larger densities of particles among the tall species. Due to resuspension of road dust, the densities of particles of Euonymus japonicus and Parthenocissus quinquefolia with low sampling height were 2-35 times to other taller tree species. For test plant species, micro-roughness of leaf surfaces and density of particles showed a close correlation. In general, the larger micro-roughness of leaf surfaces is, the larger density of particles is. Particles settling upon leaf surfaces were dominantly PM, (particulate matter less than 10 microm in aerodynamic diameter; 98.4%) and PM25 (particulate matter less than 2.5 microm in aerodynamic diameter; 64.2%) which were closely relative to human health. Constant elements of particles were C, O, K, Ca, Si, Al, Mg, Na, Fe, S, Cl and minerals with higher content were SiO2, CaCO3, CaMg(CO3)2, NaCI and 2CaSO4 x H20, SiO2. CaCO3 and CaMg(CO3)2 mainly came from resuspension of road dust. 2CaSO4 x H20 was produced by the reaction between CaCO3 derived from earth dust or industrial emission and SO2, H2SO4 or sulfate. NaCl was derived from sea salt.

[Field investigation on Salix psammophila plant morphology and airflow structure].

A field investigation in the flat sands of southern Maowusu sandy land showed that artificially cultivated single line Salix psammophila could accumulate sand because the plant decreased the windward and leeward wind velocity. There was a significant correlation (R = 0. 696) between accumulated sand volume (V2) and plant volume (V1). When the wind velocity at 4 m height of single-line S. psammophila was 6 m x s(-1), the wind velocity decreased at 3H windward, increased at 2H windward, and then steeply decreased leeward, reached the lowest value at 1H leeward and gradually recovered to the open field velocity. The protection distance of single-line S. psammophila was about 17 H', and the effective protection distance was about 13 H'. Single-line S. psamnmophila had little effect on the wind velocity above plant height.