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Various types of protected areas (PAs) are important for biodiversity conservation and essential for the 2050 Vision for Biodiversity. Rapid urban expansion affects the effectiveness of PAs in many ways. However, we still lack a clear understanding of the spatial relationship between urban expansion and different types of PAs in China during the last 30 years. Here, we analyzed the spatiotemporal changes in such relationship based on the boundaries of 2622 terrestrial PAs, as well as local Moran's and the Kruskal-Wallis H test during the period of 1992–2020 at the national, regional and provincial scales. The results showed that the number of PA threaten by urban expansion at the national scale fluctuated over time (10 to 80), while the median of the nearest distances between PAs and urban built-up areas decreased from 80.4 km to 2.6 km. At the regional scale, the PAs in east China were more affected by urban expansion than the ones in west China, with higher number of threatened PAs and closer distance between PAs and urban built-up areas. More importantly, non-national PAs were more severely affected by urban expansion than national PAs, and the proportion of threatened non-national PAs is 92.5% in 2020. Thus, future planning and management should place more attention to the non-national PAs that are severely affected by urban expansion. We investigate spatial relation between urban expansion and 2622 protected areas in China. Rapid urban expansion in recent years has posed a serious threat to PAs. Non-national PAs are more severely threatened than the national PAs. [ABSTRACT FROM AUTHOR]

In arid to semi‐arid regions, groundwater is a critical water resource heavily relied upon, with the recharge sources and patterns being predominantly shaped by climate change and regional disparities. To compare the characteristics of groundwater in the endorheic and exorheic river basins with the climate transition zone of Gansu Province, this study uses isotopic hydrochemical analyses. This study summarizes the differences in regional groundwater recharge and evolutionary patterns. The results shows that the distribution patterns of precipitation isotopes in endorheic and exorheic river basins are opposite to those of groundwater isotopes. Specifically, the precipitation in the endorheic areas is more depleted in heavy isotopes, whereas the groundwater is more enriched. Both endorheic areas and exorheic areas exhibit similar characteristics of groundwater hydrochemical evolution, evolving from low‐mineralization Mg2+HCO3− recharge water to Na+Cl− type water with saline characteristics. The former is primarily replenished by surface water, whereas the latter is primarily replenished by precipitation. Variations in recharge patterns along with the differences in climatic conditions lead to distinct groundwater conditions in the two regions. [ABSTRACT FROM AUTHOR]

Understanding the relationships between urban expansion and social/environmental features is fundamental to managing watershed and urban expansion. However, such relationships remain unclear, especially across multiple scales of watersheds. Here, we quantified the correlation between urban expansion measures and 255 socioenvironmental indicators across three scales of watersheds running through China (20, 103, and 349 watersheds) during 1992–2016 and analyzed their scaling relations. The results showed that the number of indicators showing a significant correlation with the area and speed of urban expansion increased from 132 and 153 to 234 and 237, respectively, from level 1 to level 3 watersheds. Among these indicators, urban expansion was significantly correlated with indicators of climate and anthropogenic impact. From a large scale (level 1 watershed) to a small scale (level 3 watershed), 104 and 84 socioenvironmental indicators shifted from uncorrelated to significantly correlated with urban expansion area and speed. The constraint line analysis further confirmed that some relationships were nonlinear, which suggested that the drivers and impacts of urban expansion have scaling effects. We argue that it is crucial to consider the scaling effects of urban expansion when we formulate urban or watershed management plans. [ABSTRACT FROM AUTHOR]

The direct ingestion of indoor dust particles at historical heritage sites is a primary exposure pathway for employees to heavy metals. Water-soluble ions (WSIs) and heavy metal levels, sources, bioaccessibility, and health risks associated with indoor dust in the Mogao Grottoes were analyzed using comprehensive methods to determine the differences in the concentrations and distribution characteristics of WSIs and heavy metals between statue dust and floor dust. The concentrations of WSIs and heavy metals and the magnetic values of χ lf and SIRM in indoor dust were higher than those in street dust and topsoil. The mean χ lf and SIRM of statue dust particles were 100.3 × 10 − 8 m 3 k g − 1 and 1686.9 × 1 0 − 5 Am 2 k g − 1 . Specifically, the concentration of Pb was 277 mg k g − 1 , 15-fold higher than the background value, indicating the continual receipt of heavy metals with high magnetic minerals during dust deposition. WSIs mainly originate from the weathering of surrounding rocks and earthen plaster; Pb originates from the shedding of paint of murals and sculptures; and Zn, Cu, and magnetic minerals originate from traffic sources. The bioaccessibility of heavy metals is high in the gastrointestinal phases of indoor dust. Overall, the health risks posed by heavy metals in indoor dust were low, with moderate to high risks in individual caves. Ingestion presents the highest noncarcinogenic and carcinogenic risk to employees. These results provide essential knowledge on indoor dust characteristics in the Mogao Grottoes, facilitating strategies for dust pollution mitigation and employee health risk control. [ABSTRACT FROM AUTHOR]

Land use significantly affects the rate and amount of groundwater recharge. To understand these patterns, stable isotope analyses (δ2H and δ18O) and hydrochemical methods were employed to study the recharge and evolution of groundwater. MixSIAR Bayesian mixture modelling and statistical regression techniques were utilized to investigate the influence of land‐use type on groundwater recharge and to calculate the contribution of various water sources to different groundwater types. These findings are important for effective management and conservation of groundwater resources. The groundwater in all studied areas displayed a magnesium bicarbonate type with notable cation exchange, and also demonstrated the dissolution of carbonate and weathering of silicate. Results from the Bayesian mixture model indicate that 69.3% of the groundwater in the Loess Plateau region was recharged by precipitation, while 86.9% of the groundwater in the loess hilly‐gully region was recharged from the surface water. Groundwater recharge was more rapid in the loess hilly‐gully region than in the Loess Plateau and was less sensitive to the land use type in the former. Dryland‐moderate coverage grassland was found to be most conducive to groundwater infiltration, whereas monotypic dryland and high‐coverage grassland inhibited infiltration to some degree. To maintain balanced soil erosion control, an increase the area of moderate‐coverage grasslands in the Loess Plateau region is recommended. [ABSTRACT FROM AUTHOR]

The enrichment levels, sources, and potential hazards of heavy metals (HMs) and magnetic minerals in street dust and sand-dust storm from an extremely arid city (Dunhuang) in the northwest of China were analyzed. The assessment was performed using pollution indices, magnetic parameters, positive matrix factorization (PMF), and risk assessment models. Average enrichment levels of HM (including Cd, Zn, Pb, Cu, Cr, Co, and Ni) in street dust were higher than those in urban topsoil and the background values. The enrichment factor, pollution load index (PLI), and geoaccumulation index showed that the HMs came from both natural and anthropogenic sources, with Cu, Zn, Pb, and Cd being strongly influenced by anthropogenic sources. The means mass-specific susceptibility (χlf) and saturation isothermal remanent magnetization (SIRM) of street dust were 135.65 × 10−8 m3/kg and 1792 × 10−5Am2/kg, respectively, indicating that the street dust continuously receives pollutants containing high levels of coarse pseudo single-domain and multidomain ferromagnetic minerals. Ni, Zn, Cd, Cr, Fe, and ferromagnetic particles were principally associated with the industrial source and accounted for about 30.4% of these HM contents. Pb and Co were mainly produced from coal mining and coal combustion sources. Cu was principally associated with traffic emissions. Al, Mn, and Co were mainly generated by natural sources, contributing 38.9%. The ecological risk of HMs in street dust was moderate with considerable risk in individual sites, driven by Cd. The non-carcinogenic risks of HMs were within safety limits, and the carcinogenic risks were below the receivable values. [ABSTRACT FROM AUTHOR]

Debris flow hazards can occur easily in loess regions, due to the particular characteristics of loessic material. Some of them have historically caused considerable damage to both the natural and the human environment. Little research has been conducted into the impact pressures caused by debris flows varying with densities and weights in loess regions. Flume experiments were conducted to estimate the impact pressures of debris flows, and the maximum impact pressure was measured. Moreover, hydrodynamic and hydrostatic models were improved by using these experimental results. Finally, after combining these results with a dimensionless analysis and Buckingham's π theorem, the Froude number and the Reynolds number were able to be introduced in order to construct a comprehensive dimensionless equation for debris flows. The results showed that the velocity ranged from 1.23 to 3.62 m/s when the debris flow density increased from 1100 to 2300 kg/m3 and the mixture weight rose from 100 to 500 kg. The debris flow depth was between 2.7 and 13.4 cm, and the maximum impact pressure ranged from 1.23 to 28.41 kPa. In addition, the empirical parameters of hydrodynamic and hydrostatic models were modified and valued at 5.08 and 9.48, respectively, which were significantly different from the empirical parameters for earth-rock areas. Specifically, the modified hydrodynamic model and modified hydrostatic model were observed to perform very well for debris flows with comparatively high Froude debris flow numbers. The maximum dimensionless impact pressure was expressed as a power function of both the Froude number and the Reynolds number. A comprehensive maximum dimensionless impact pressure formula for debris flows was coupled with the Froude number and the Reynolds number and expressed as a power function. Results indicated that the modified model and the comprehensive approach can both be applied to the loess regions of China and can provide a better understanding of loess debris flow mechanisms, as well as feed into engineering design work and risk assessments in loess regions affected by debris flows. [ABSTRACT FROM AUTHOR]

• We developed a method to quantify seasonal supply–demand variations of ecosystem service. • Water provisioning service is pronouncedly mismatched in winter. • The developed method based on SWAT has potential to estimate other water-related services. • Reservoirs are important for addressing unmatched supply–demand relation at the watershed scale. The match and mismatch between the supply and demand of ecosystem services (ESs) are closely related to watershed sustainable development. Previous studies have mainly focused on annual or interdecadal matching relationships, and little is known about the seasonal variations of the ES supply–demand relationship. Based on the SWAT (Soil and Water Assessment Tool) model and statistical data, we took the Guanting Reservoir Basin, a transitional ecosystem from semi-arid areas to arid areas, as the study area to analyze the supply and demand of water provisioning services and soil conservation services and identified their matching relationship on the seasonal scale. The results showed that the water provisioning services was in short supply, with a supply–demand ratio of 0.81, whereas the supply of soil conservation services was in excess of demand. In terms of seasonal variation, the mismatch of water provisioning services was particularly severe in winter, followed by that in spring. The mismatch of soil conservation services was relatively severe in winter, followed by that in summer. Such mismatches imply that we must pay attention to the misallocation of resources caused by seasonal variations. It is crucial that policy-makers consider the role of reservoirs and water transfer in providing seasonal water sources for sustaining water resources in transitional areas, and optimize land management to prevent the aggravation of soil erosion in winter. [ABSTRACT FROM AUTHOR]

Direct ingestion of sandstorm particles is an important pathway in human exposure to heavy metals. This study investigated the potential health risks of heavy metals transported in sandstorms from Dunhuang to Lanzhou in northwestern China using environmental magnetic parameters and metal bioaccessibilities in simulated gastric and intestinal tracts. The mean magnetic susceptibility of sandstorms in Lanzhou was 366.86 × 10 -8 m 3 /kg, which was more than 5-fold higher than that of sandstorms in Dunhuang, indicating that these sandstorms continuously receive heavy metals with high magnetic mineral content along their pathways. Heavy metal concentrations in sandstorms were higher than background values and those in urban topsoil. Enrichment factors and pollution load indices showed that these heavy metals were derived from both natural and anthropogenic sources, with Cu, Zn, Pb, and Cd being strongly influenced by anthropogenic sources. The bioaccessibilities of Cd, Cu, Zn, and Pb in the sandstorms of Lanzhou were very high, ranging from 22.69% (Cu) to 50.86% (Pb) for gastric phase, and 12.07% (Pb)-22.11% (Cd) for interstinal phase, with the significant reduction in χ lf of the physiologically-based extraction testing (PBET) treated sandstorms. The magnetic minerals are significant correlation with the concentrations of heavy metals in sandstorm and effect the release of heavy metals during human digestion process. The overall ecological risk posed by heavy metals contained in sandstorms was relatively low; however, the risk was moderate to high at individual sites. Ingestion posed the highest carcinogenic and non-carcinogenic risks for both adults and children, with the risk for children being higher., Competing Interests: Declaration of competing interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in/ or the review of the manuscript entitled “Application of magnetic susceptibility and heavy metal bioaccessibility to assessments of urban sandstorm contamination and health risks: case studies from Dunhuang and Lanzhou, northwest China”., (Copyright © 2022 Elsevier B.V. All rights reserved.)