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The study of the geochemical characteristics of rare earth elements (REE) in coal has important indicative significance in terms of sedimentary environment and material source in coal basin. In order to further explore the geochemical characteristics of systematic elements in Carboniferous-Permian coal in the Ordos Basin, taking the Permo-Carboniferous Taiyuan Formation (Fm) coal in Nindong coalfield as the research object to study the geochemistry characteristics of REE and discussed its occurrence characteristics and origin, base on the data from X-ray fluorescence spectrometer and plasma mass spectrometer. The result show that: The average content of REE in Permo-Carboniferous Taiyuan Fm coals from Nindong coalfield is 91.91 μg/g, which is lower than the average content of 135.89 μg/g in China coals. The obviously negative Eu abnormity, unobvious Ce abnormity, LaN/YbN, LaN/LuN, LaN/SmN, LREE/HREE and the REE distribution patterns normalized by the upper crust all reflect the characteristics of low fractionation of light and heavy REE and relative enrichment of heavy rare earth elements in coals. The REE in the coal inherit the characteristics of the rare earth elements in the source rock area, and in the sedimentary and coal-forming stages, under the combined action of temperature, pressure, pH value and redox conditions. The REE in coal mainly occurs in clay minerals, which can be verified by the positive correlation between rare earth elements and ash, Si, Al, Na, K. The diagrams of ∑Lei-La/Ibu, ∑-Li-δ/δ-Ou, and Σli-La/Lu indicate that the Carboniferous-Permian coal in the Ningdong coalfield was formed in the sedimentary setting of the Lower Delta Plain and the Lower Delta-Delta Plain, all of which were affected by seawater to varying degrees. The source, content and occurrence characteristics of REE in Permo-Carboniferous Taiyuan Fm coals from Ningdong coalfield are mainly controlled by the supply of felsic terrigenous clasts, but also affected by local micro-topography, micro-geomorphology and micro-environment, the impact of seawater and diagenesis are limited.

Strengthening agricultural carbon emissions (ACE) reduction is an inherent requirement to promote the integrated development of ecological greenery in the Yangtze River Delta (YRD), and it has a significant driving effect and benchmarking significance for China to achieve carbon peaking and carbon neutrality. Based on panel data of 41 cities in the YRD from 2001 to 2019, this study reveals the spatial and temporal evolution pattern of ACE and identifies the influencing factors through methods such as CV, SDE, ESDA and SDM. The results are summarized as follows: (1) the ACE in the YRD show a fluctuating downward trend, and the gap between cities tends to widen; (2) the YRD shows emission characteristics dominated by agricultural material input, with a proportion of over 50% over the years, followed by rice cultivation and livestock breeding with the lowest proportion. In addition, Jiangsu and Anhui have higher proportions, followed by Zhejiang, and Shanghai; (3) these cities with high ACE are mainly located in the northwest regions of the YRD, and those with low ACE are mainly located in the southeast regions of the YRD. Furthermore, cities in the YRD have a positive global spatial autocorrelation, and the local spatial agglomeration pattern has strong characteristics of stability and spatial dependence; (4) the agricultural economic development level has an inverted U-shaped effect on ACE in the YRD. Meanwhile, the total rural population, total power of agricultural machinery, and urbanization level have a significant positive impact, while the agricultural planting structure and trade openness level are not significantly affected, but the rural non-farm employment level have a significantly negative impact on ACE. SDM further supports the influence of various factors, and it can be found that the agricultural economic development level and trade openness level exhibit significant negative spillover effects. [ABSTRACT FROM AUTHOR]