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Most studies assessing soil environmental capacity (EC) often overlook the impact of heavy metal sources. Analyzing the sources of heavy metals (HMs) provides a better understanding of regional environmental capacity characteristics and their dynamic changes. The current study focuses on the surface soil of Shantou, using 511 soil samples to assess the soil environmental capacity. Results indicate that the contents of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in Shantou's surface soil are notable, with lead moderately enriched and other metals lightly enriched. The principal component analysis (PCA) identifies five primary sources of heavy metals: mixed natural and agricultural sources, mixed agricultural and industrial sources, industrial sources, mining sources, and quarrying sources. The primary source contributing significantly to soil HM concentrations in Shantou City is a complex interplay between natural geological processes and extensive agricultural practices. In terms of static environmental capacity, Zn, Cr, Ni, Pb, Cu, As, Hg, and Cd are ranked in descending order. The overall environmental capacity for heavy metals in the soil is at a medium level, influenced by geological backgrounds. However, regions such as Yanhong Town, Guiyu Town, and Chendian Town face lower environmental capacities due to comprehensive human activities, posing certain risks. This study provides a scientific reference for forecasting, controlling soil heavy metal pollution, and improving soil quality and environmental capacity in Shantou City. [ABSTRACT FROM AUTHOR]

Granite, a principal component of continental crust, emerges at the Earth's surface through crustal movements, creating diverse landforms. The Queshi region, comparable to Huangshan in its granite hilly landscape, stands as a representative granite landform in China, yet its origin remains incompletely studied. This investigation utilizes surface landscape and cave analyses to elucidate the characteristics and determining factors of granite landforms in the Queshi region, to comprehend the formation mechanisms of these unique landforms. In the surface investigation, field surveys and aerial photography, employing a DJI Phantom 4 RTK drone, were utilized to measure the morphology and dimensions of exposed rock egg sizes on cliff faces and joint spacing. The survey results facilitated an overall classification of surficial landscapes, encompassing the proportion of rock egg sizes on the mountain and the spacing between the vertical and horizontal joints. To assess mountain development concerning stone eggs, cave orientation and elevation were determined using a rangefinder and GPS measurements, while different contact relationships between stone eggs were investigated. By amalgamating domestic and international granite development theories with field investigation results, this study delves into the geological structure of the surrounding areas, the characteristics of granite landforms, and the factors governing the landform formation of granite geomorphology in the Queshi area. The findings indicate that 1) rocks in the Queshi scenic area have evolved into various rock eggs through subsequent weathering processes, manifesting as grotesque formations resembling humans, genies, or animals, and 2) granite mountain bodies in the Queshi region can be categorized into three types: rock egg mountains, peak forest mountains, and steamed bun mountains. Stone egg mountains exhibit a unique form with round, large stone eggs stacked atop each other, peak forest mountains comprise elongated rock eggs or blocks due to narrowly spaced vertical joints, while steamed bun mountains lack obvious joints and fractures, presenting gently rounded mountain shapes. Furthermore, 3) granite caves in the Queshi scenic area are classified into four categories based on different formation processes: core stone caves, collapsed caves/rock egg caves, fissure caves, and niches. Core stone caves form when weathered material in the gaps between stone cores is carried away by flowing water without causing any movement of the core stones. Fissure caves, relatively rare and small in scale in the Queshi scenic area, are formed along large fractures created by bedrock breaks. Niches are concave grooves formed at the base of rock bodies or rock eggs, buried by rock debris or soil, storing more rainwater than bare rock surfaces and enhancing chemical weathering. After external runoff removed the debris, the rock base became exposed and formed concave grooves. Finally, 4) the weathering crusts of the Queshi region formed before the subsidence of the Rongjiang fault, during which the Queshi Mountains experienced relative uplift. Consequently, the weathering crusts continued to weather, forming the present granite landforms. Weathering occurs through the rock joints of the parent rock of the weathered crusts, with the degree of damage to the rock determined by joint density. The greater the joint density, the more extensive the damage; conversely, the smaller the joint density, the less the damage. Therefore, mountain morphological differences in the Queshi region are primarily caused by variations in joint spacing rather than climate or rock-type influences.

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Based on routine monitoring data of air quality and meteorological data in Shantou City during 2015 -2019, temporal-spatial variation characteristics of O3 pollution and its correlation with meteorological conditions in Shantou City were explored. The research results showed that O3 pollution days in Shantou City showed an increasing trend year by year, and O3 pollution had far-distance transportation and the development trend from offshore Nan'ao Island to urban district. In spring and autumn, there was serious O3 pollution, and it was the most prominent in October. Its diurnal variation in O3days was mainly wide-peak type in the afternoon, showing as that O3 concentration declined slowly after the noon. In O3 pollution days, higher O3 concentration was easy to appear at night, causing that O3peak in the second day was uplifted, and there was continuous O3 pollution. Combining backward trajectory analysis chart, it was found that Shantou was mainly affected by coastal transport of northerly polluted air mass, and it was transported into Shantou City from the east to the northeast. O3 from long-distance transmission superimposed with locally generated O3 which commonly pushed up the level of O3 concentration. The weather of O3pollution in Shantou City had the characteristics of high temperature and low humidity. There was 25 -- 30 °C of temperature interval and 46% --60% of relative humidity interval, and it was accompanied by grade-2 easterly wind. [ABSTRACT FROM AUTHOR]