The Paleoproterozoic basement underlying the Cathaysia Block remains relatively understudied, and its contribution to the region’s tectonic evolution requires further investigation. In this study, we examined Jurassic Laiziling and Jianfengling A-type granites and identified a significant number of zircon grains exhibiting varied CL imaging characteristics. These zircons yielded four distinct age groups: 700 Ma. Detailed trace element analysis revealed that these age groups correspond to different zircon types: metamorphic recrystallized zircons (700 Ma). Through host rock and tectonic setting discrimination, we consider that the inherited zircons have host rocks of S-type granites and basic rocks, and these were formed in subduction-compression tectonic environments. In comparison to local significant geological events in history, we propose that these zircons record multiple tectonic events in the South China Block, including the amalgamation of the Yangtze and Cathaysia Blocks during the Neoproterozoic; an intracontinental orogenic event that occurred during the Middle Paleozoic; and subduction–exhumation processes related to the Paleo-Pacific slab; as well as extensional metamorphic events from the Cretaceous to Tertiary events. A comparison of Hf isotopic compositions revealed that zircons aged 500–200 Ma and >700 Ma share a 2.5–1.6 Ga crustal evolution zone, indicating that multiple re-melting events have occurred within the Paleoproterozoic basement of the Cathaysia Block.

Research into river processes in different climatic and geomorphic areas is vital for a clearer understanding of the non-linear responses of rivers to climate change. The Huaihe River (HHR) Basin, located in China’s North–South Transition Zone (NSTZ), provides an ideal environment in which to explore river responses to climate change within a humid/semi-humid transitional area. Based on optically stimulated luminescence (OSL) and ¹⁴C dating, combined with sedimentary stratigraphic analyses, we reconstructed the river processes of three sedimentary sequences in the upper HHR since the Late Quaternary. Our results showed that the upper HHR was characterized by aggrading meandering channels from the Last Glacial Maximum (LGM) to 0.5 ka, and an aggrading wandering channel from 0.2 ka to the present. Two periods of downcutting occurred during 5.8–3.0 and 0.5–0.2 ka, respectively. The river incision is potentially linked to changes in the climate during the Mid–Late Holocene transition and the Little Ice Age (LIA). However, there have been no marked changes in channel patterns in the upper HHR since the LGM. This phenomenon reflects the influence of vegetation on channel patterns during climate change. Our results showed that the fluvial processes in different climatic and geomorphic areas are controlled by the local hydroclimatic regime.

Pruned tea leaves are discarded or burned as agricultural residue, causing resource waste and serious environmental problems. Pruned tea leaves with a rich number of cellulosic and polyphenolic components could be used as biomass feedstocks and reducing agents to synthesize ZVI-embedded biochar. In this work, a green, inexpensive and convenient method was developed for the synthesis of nanoscale zero-valent iron embedded biochar (TLBC-nZVI) using pruned tea leaves. TLBC-nZVI showed excellent performance in Cr(VI) removal (166.65 mg g−1) from aqueous solutions. Isothermal, kinetic and thermodynamic studies showed that Cr(VI) removal fit well with the Freundlich model and pseudo-second order model. Additionally, the removal process was a chemical, spontaneous and endothermic reaction. The removal mechanisms were as follows: (i) protonated TLBC-nZVI adsorbed anionic Cr(VI) by electrostatic interaction under acidic conditions; (ii) Fe0, Fe(II) and some surface functional groups (such as –NH2 and –OH) reduced Cr(VI) to Cr(III); and (iii) Cr(III) was removed through complexation, physical adsorption and coprecipitation.