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Climate change and human activities have caused various ecological risks to coastal urban agglomerations. Ecological security refers to the state of health of an ecosystem and its integrity. An objective and comprehensive evaluation of ecological security is significant for protecting the structure and function of coastal ecosystems. The driving force–pressure–state–impact–response (DPSIR) model was used to construct a dynamic simulation model of ecological security in the Xiamen–Zhangzhou–Quanzhou region (XZQR), located on the eastern coast of China. The ecological security level (ESL) characteristics of the spatial and temporal patterns were evaluated by calculating the ecological security index (ESI). Obstacle factors were analyzed as well. The results show the following: (1) From 2011 to 2021, the average ESI rose from 0.238 to 0.686 and went through a relatively insecure stage (2011–2015), a critical stage (2016–2019), and a relatively secure stage (2020–2021). (2) The ESI level in Quanzhou was higher in the early stage, and the level of ecological security in Zhangzhou showed a significant rising trend, increasing by 0.541. Its increase depended on increases in the impact layer. (3) The impact layer is the main obstacle layer affecting the ESL, and the main obstacles include CO2 emissions (0.117), annual rainfall (0.091), general public budget expenditures (0.082), GDP growth rates (0.082), and green coverage in built-up areas (0.075). Therefore, we recommend promoting the complementary advantages of the XZQR and implementing ecological restoration projects. [ABSTRACT FROM AUTHOR]

Climate change and human activities have caused various ecological risks to coastal urban agglomerations. Ecological security refers to the state of health of an ecosystem and its integrity. An objective and comprehensive evaluation of ecological security is significant for protecting the structure and function of coastal ecosystems. The driving force–pressure–state–impact–response (DPSIR) model was used to construct a dynamic simulation model of ecological security in the Xiamen–Zhangzhou–Quanzhou region (XZQR), located on the eastern coast of China. The ecological security level (ESL) characteristics of the spatial and temporal patterns were evaluated by calculating the ecological security index (ESI). Obstacle factors were analyzed as well. The results show the following: (1) From 2011 to 2021, the average ESI rose from 0.238 to 0.686 and went through a relatively insecure stage (2011–2015), a critical stage (2016–2019), and a relatively secure stage (2020–2021). (2) The ESI level in Quanzhou was higher in the early stage, and the level of ecological security in Zhangzhou showed a significant rising trend, increasing by 0.541. Its increase depended on increases in the impact layer. (3) The impact layer is the main obstacle layer affecting the ESL, and the main obstacles include CO2 emissions (0.117), annual rainfall (0.091), general public budget expenditures (0.082), GDP growth rates (0.082), and green coverage in built-up areas (0.075). Therefore, we recommend promoting the complementary advantages of the XZQR and implementing ecological restoration projects.

The boundary between Cretaceous and Paleogene (K/Pg) plays an important role in deciphering the Earth's history and biological evolution from Mesozoic to Cenozoic. As such, the delineation and characterization of the boundary layer has attracted significant attention. In this study, X-ray diffraction (XRD) and elemental analyses were conducted to characterize the samples of boundary layer and the layers around Agost and Caravaca, Spain. The XRD results showed that the layers immediately above and below the boundary layer are made of limestone, while in the boundary layer, a significant increase in the clay minerals smectite, kaolinite, and illite was observed. The major element analyses revealed an increase in Si and Al contents, confirming the presence of clay minerals. The trace element analyses showed elevated concentrations of V, Cr, Ni, Zn, Pb, and Th, but not for Rb, Cu, and U. The rare Earth element (REE) analyses showed elevated La, Ce, and Nd concentrations in the boundary layer. Correlation analyses between selected trace elements and REE showed good agreements, with R2 values of about 0.9. The results agreed well with the finding in the area, except the lower contents of Rb, Cu, and U; thus, they may promote further studies to make detailed comparisons. [ABSTRACT FROM AUTHOR]

The boundary between Cretaceous and Paleogene (K/Pg) plays an important role in deciphering the Earth’s history and biological evolution from Mesozoic to Cenozoic. As such, the delineation and characterization of the boundary layer has attracted significant attention. In this study, X-ray diffraction (XRD) and elemental analyses were conducted to characterize the samples of boundary layer and the layers around Agost and Caravaca, Spain. The XRD results showed that the layers immediately above and below the boundary layer are made of limestone, while in the boundary layer, a significant increase in the clay minerals smectite, kaolinite, and illite was observed. The major element analyses revealed an increase in Si and Al contents, confirming the presence of clay minerals. The trace element analyses showed elevated concentrations of V, Cr, Ni, Zn, Pb, and Th, but not for Rb, Cu, and U. The rare Earth element (REE) analyses showed elevated La, Ce, and Nd concentrations in the boundary layer. Correlation analyses between selected trace elements and REE showed good agreements, with R2 values of about 0.9. The results agreed well with the finding in the area, except the lower contents of Rb, Cu, and U; thus, they may promote further studies to make detailed comparisons.