Content of Heavy Metal in the Dust of Leisure Squares and Its Health Risk Assessment—A Case Study of Yanta District in Xi’an

Taking Yanta District in Xi’an as the research object, the present study measures the contents of Cadmium (Cd), Lead (Pb), Copper (Cu), Nickel (Ni), and Chromium (Cr) in dust samples and further assesses the health risk of heavy metals intake through dust based on the assessment method of human exposure risk proposed by U.S. EPA, with an aim to investigate the content of heavy metal in the dust of leisure squares and its exposure risk. As the results indicate, the average contents of five heavy metals are obviously higher than the soil background value in Shaanxi Province. Therefore, Cd, Ni, Cu, Pb, and Cr are obviously enriched in urban surface dust in Shaanxi Province, due to the influence of human activities. In addition, it can also be found that the non-carcinogen exposure risk in children is significantly higher than that in adults with the risk values of these five heavy metals all one order of magnitude higher than those of adults. Irrespective of whether addressing the results for children or adults, the non-carcinogen exposure doses of five heavy metals are sorted as Cr > Pb > Cu > Ni > Cd. According to the present situation, for a child, the total non-carcinogenic risk values of five heavy metals have exceeded the safety limit in 11 of the 20 leisure squares in Yanta District of Xi’an. That means the leisure squares are no longer suitable for physical and recreational activities. For the five heavy metals, the average non-carcinogenic risk value of Cr is largest, and causes the largest threat to health in Yanta District, Xi’an. The carcinogenic exposure doses of the heavy metals Cr, Cd, and Ni are very low in respiratory pathways and there is no carcinogenic health risk. In general, the Cr content in dust in domestic cities is higher than that of foreign cities; however, the Pb content is much lower

Understanding China’s Urban Rainstorm Waterlogging and Its Potential Governance

Urban rainstorm waterlogging is one of the most important problems in urban development and a comprehensive embodiment of urban diseases. China is facing a severe risk of rainstorm waterlogging disasters, which is affecting sustainable development. Urban rainstorm waterlogging in China is caused by many factors, including natural factors and human factors, such as climate warming, unreasonable urban construction, inadequate upgrading of urban fortification standards, etc. Based on the analysis of the current strategies to deal with urban waterlogging around the world, including an increase in surface infiltration, and a reduction in runoff (and its various impacts), this paper holds that the connotation and goal of these measures are highly consistent with the construction of a sponge city in China. Based on the analysis of the problems, including construction of an urban rainwater recovery system, construction of urban rainwater storage facilities, and construction of data platforms faced by China’s sponge city, this paper puts forward the guiding principles of promoting the construction of a sponge city. The guiding principles are to cooperate to deal with climate change and ecological civilization construction, to study the foreign experience, and to unite multiple subjects, integrate multiple elements, design multiple processes, form a joint force, and create an all-round response system to deal with urban rainstorm waterlogging. Then, this paper gives policy recommendations on how to deal with the urban rainstorm waterlogging disasters, which include improving the defense standards, encouraging social participation, popularizing the construction of sponge cities, perfecting the monitoring and early warning system, strengthening the scientific planning of cities, strengthening the ability of dealing with catastrophes in metropolitan areas, the overall planning of cross-regional responses, and enhancing the awareness of decision makers. Finally, this paper expounds the reference significance of urban rainstorm waterlogging control in China to the global audience. This paper explores the significance of comprehensively and scientifically understanding urban rainstorm waterlogging disasters, and provides support for long-term planning and high-quality construction of future safe cities

Vertical distribution of sand layer CO2 concentration and its diurnal variation rules in Alxa desert region, northwest China

In order to ascertain the vertical distribution of sand layer CO2 concentration from the Alxa desert region as well as its impact on atmosphere CO2 and action on global carbon cycle, infrared CO2 monitor was used to perform 19 drilling holes to observe CO2 concentration day and night in the Nuoertu megadunes region, Shapotou trellis dunes region and Minqin barchan dunes region. The results showed that atmosphere CO2 concentration in Alxa desert region is lower than that in the sand layer of 1-5 m depths, which manifests that it is the source region of atmosphere CO2 and it releases CO2 day and night during warm seasons. The diurnal variation of sand layer CO2 concentration in extremely arid Alxa desert region shows obvious regularity: CO2 concentration of every depth varies from low to high to low from 8:00 am to next day 7:00 am. The diurnal variation of temperature is the main cause of diurnal variation of sand layer CO2 concentration, which are significantly correlated positively. In extremely arid desert region, sand layer moisture content is the main factor that determines sand layer CO2 concentration

Grain size and heavy metal assessment in barchan dunes surrounding the Talatan PV power generation area, Qinghai Province

Heavy metal contamination in sediments near photovoltaic (PV) power generation areas poses potential environmental risks, requiring detailed characterization and source apportionment to facilitate sustainable management. This research explores the characteristics of sediment grains and the concentrations of heavy metals present in surface sediments from barchan dunes proximal to the Talatan Photovoltaic (PV) power generation area, located within Gonghe County, Qinghai Province. The sediments displayed an average grain size within the medium sand range, with marginal differences discernible between the windward and leeward slopes. With the exception of Mn, Cu, Zn, V, Pb, and Ba, concentrations of the remaining metals were found to surpass the baseline levels established by Chinese aeolian soil data, alluding to potential anthropogenic influences. Through employing coefficients of variation in multivariate statistical analysis, it was identified that the concentrations of Cr and Co were significantly elevated, suggesting potential anthropogenic contamination, which may be associated with photovoltaic industrial activities. Specifically, the elevated concentrations of Cr and Co suggested anthropogenic contamination, potentially associated with photovoltaic industrial activities. Utilizing a combination of Correlation Coefficient Analysis, Principal Component Analysis, and Cluster Analysis, three potential sources of heavy metals were identified: (1) industrial origin for elements such as Cu, Cr, Ni, Zn, and As; (2) elements with limited direct application in the photovoltaic industry but associated with materials and energy storage, namely Ba, V, and Mn; (3) anthropogenic inputs related to construction materials and battery storage systems in the photovoltaic park, specifically Co and Pb. The findings offer a significant understanding of the heavy metal characteristics and sources in proximity to the Talatan PV power generation area, emphasizing the impact of human activities on environmental quality. These insights underscore the necessity for enhanced monitoring and management of industrial activities to mitigate potential environmental impacts. Further research is recommended on a broader spatial scale to yield a more comprehensive understanding of this subject

Flood Disaster Monitoring and Emergency Assessment Based on Multi-Source Remote Sensing Observations

Flood disasters are one of the most serious meteorological disasters in China. With the rapid development of information technology, individual monitoring tools could not meet the need for flood disaster monitoring. Therefore, a new integrated air-space-ground method, based on combined satellite remote sensing, unmanned aerial vehicle remote sensing and field measurement technology, has been proposed to monitor and assess flood disasters caused by a dam failure in Poyang County, Jiangxi Province. In this paper, based on an air-space-ground investigation system, the general flooded areas, severely affected areas, and more severely affected areas were 53.18 km2, 12.61 km2 and 6.98 km2, respectively. The size of the dam break gap was about 65 m and 34.7 m on 22 and 23 June. The assessment precision was better than 98%, and the root mean square error (RMSE) was 0.86 m. The method could meet the needs for flood disaster information at different spatiotemporal scales, such as macro scale, medium scale and local small scale. The integrated monitoring of flood disasters was carried out to provide the whole process and all-round information on flood evolution dynamics, the disaster development process for flood disaster monitoring and emergency assessment, and holographic information for emergency rescue and disaster reduction, as well as to meet the need for different temporal and spatial scales of information in the process of disaster emergencies

Hydrological Cycle and Lake Water Source Indicated by Microrelief-Evaporite-Vegetation-Runoff Assemblage of Badain Jaran Desert

The hydrologic process of the sandy desert remains a focus in research in arid areas. Three major natural phenomena that can indicate the hydrological cycle in the extremely dry Badain Jaran Desert were found, namely the assemblage of megadune microrelief and evaporite, megadune vegetation and microrelief, as well as lakeside runoff and vegetation. The microrelief sand layer water, evaporite minerals, and lakeside hydrogeological features were analyzed by the drying and weighing method, environmental scanning electron microscopy with energy spectrum analysis functions, and a hydrogeological borehole survey. The water content of the microrelief 0-0.5 m sand layer is between 4.7% and 9.3%. The evaporite minerals are mainly composed of calcite (CaCO3) and gypsum (CaSO4). The shallow groundwater system in the off-shore area of lakes consists of an aeolian sand layer, a peat layer, and a lacustrine sedimentary layer, and the phreatic water with a thickness of 20 cm to 40 cm is reserved in the bottom of aeolian sand layer with a peat layer as a waterproof baseboard. Based on these results, the above three natural phenomena can be explained as follows: (1) The assemblage of megadune microrelief and evaporite was caused by the outcropping of water from megadune vadose zone in the form of preferential flow for a long time. Its leading edge differential wind erosion and calcium cemented fine sand layer indicate that water from the megadune vadose zone moves to and recharges the microrelief water along the micro-scale fine sand layer, during which, it features a multiple layer as it is controlled by a vertical dune bedding structure. (2) The small-scale assemblage of megadune vegetation and microrelief indicates that the water from the megadune vadose zone moved laterally and led to vegetation development, and the assemblage of microrelief and vegetation at a slope scale indicates that the vadose zone water presented multilayer enrichment and runoff producing due, to a great extent, to the bedding structures of different spacial locations. (3) The assemblage of lakeside runoff and vegetation is related to the phreatic water recharged by precipitation surrounding the lake, which indicates that the megadune water recharged by precipitation moved to the bottom of the megadune and constituted supply to the lake water. The three assemblages fully demonstrate that the megadune water recharged by precipitation in this desert could recharge the groundwater water and even lake water in the form of preferential flow due to the control of the bedding structure of different scales within the megadune. The results of lake water balance and the occurrence conditions of phreatic water surrounding the lake imply that the precipitation in this desert plays an important role in sustaining the lake. This study provides reliable evidence for revealing the essence of the hydrological cycle and the source of lake water in the Badain Jaran Desert, which indicates that although precipitation is small, it cannot be ignored in arid sandy desert areas

Mechanistic Investigation of Typical Loess Landslide Disasters in Ili Basin, Xinjiang, China

In the period from 2010 to 2018, a total of 302 geological disasters occurred in the Xinjiang Autonomous Region, China, of which 136 occurred in the Ili Basin. Compared with those in other regions, the loess landslides in the Ili Basin are strongly influenced by the seasonal freeze–thaw effect. Taking the No. 2 Piliqinghe landslide as an example and based on the field geological investigation, it was found in the present study that the main triggering factors of this landslide were the snowmelt erosion of the slope toe and meltwater infiltration into the trailing edge of the slope. The mechanism of loess landslide instability was studied using numerical simulation. The results showed that (1) the Piliqinghe landslide disaster was formed through a process composed of the local sliding of the leading edge → the creep sliding and tension cracking of the slope surface → the overall sliding stage; (2) the infiltration of snowmelt was the direct cause of the landslide formation; (3) the fluvial erosion and softening caused the soil of the slope toe to slide. The results can be used as a reference for the analysis of the disaster mechanism and movement characteristics of similar loess landslides

The Net Influence of Drought on Grassland Productivity over the Past 50 Years

The focus of this paper is on the grassland productivity response to drought under the background of climate change. There is an established lag impact on the response of grassland ecosystems to drought events, which may have additional effects on subsequent drought events. Meanwhile, due to climate change interference, the influence of drought on grassland productivity over the past 50 years is not simply equal to the algebraic sum of all the historical drought events. In the Inner Mongolia grassland, precipitation deficit plays a leading role in causing drought. Therefore, taking into consideration the impacts of drought lag effect and climate change, in this paper, we focus on the net influence of drought on grassland productivity over the past 50 years on the basis of long-term precipitation deficit, we identify the interference effect from different climate factors (precipitation and temperature) by using different scenario simulation tests, and therefore, further clarify the net influence on the grassland productivity of Inner Mongolia over the past 50 years

Permeability and Groundwater Enrichment Characteristics of the Loess-Paleosol Sequence in the Southern Chinese Loess Plateau

To determine the permeability characteristics and the groundwater enrichment conditions of loess and paleosol layers, this article systematically investigated the permeability, magnetic susceptibility, porosity, and carbonate mass percentage of representative loess-paleosol layers (L1 to S5) on the Bailu tableland in the Chinese Loess Plateau south. The result of in situ permeability measurements showed that the average time to reach quasi-steady infiltration of loess layers is shorter than that of paleosol layers. In addition, loess layers have higher porosity and better water storage spaces than paleosol layers and were prone to form aquifers. Paleosol layers, on the contrary, are more likely to form aquitards. The difference between loess and paleosol in permeability, porosity and groundwater enrichment conditions is largely attributed to lower intensity pedogenesis of loess, which is in turn ascribed to the colder and drier palaeoclimatic conditions. It is worth mentioning that the CaCO3 concretion layer is a good aquifuge for its compact structure. Generally, the empirical formula of the Koctakob formula is applicable for describing the permeability rule of loess and paleosol layers, and the parameters of the empirical formulas can provide an important reference for hydrological and agricultural departments. In this regard, the Quaternary climatic change theory can contribute to the hydrogeology of the Chinese Loess Plateau, and the regional climatostratigraphy can be regarded as a baseline for local water resource positioning and revegetation in such a semi-arid area, which broadens the application field of Quaternary climatic change theory. Meanwhile, it also provides a reference path for solving water shortages of other loess distribution areas in China and other countries

The Net Influence of Drought on Grassland Productivity over the Past 50 Years

The focus of this paper is on the grassland productivity response to drought under the background of climate change. There is an established lag impact on the response of grassland ecosystems to drought events, which may have additional effects on subsequent drought events. Meanwhile, due to climate change interference, the influence of drought on grassland productivity over the past 50 years is not simply equal to the algebraic sum of all the historical drought events. In the Inner Mongolia grassland, precipitation deficit plays a leading role in causing drought. Therefore, taking into consideration the impacts of drought lag effect and climate change, in this paper, we focus on the net influence of drought on grassland productivity over the past 50 years on the basis of long-term precipitation deficit, we identify the interference effect from different climate factors (precipitation and temperature) by using different scenario simulation tests, and therefore, further clarify the net influence on the grassland productivity of Inner Mongolia over the past 50 years