Soil heavy metal (HM) control has become a pressing global ecological and environmental issue, with a significant focus on the western Dabie Mountain in China, a region that is recognized for its ecological barriers and water sources. We analyzed the concentrations, pollution status, and potential ecological risks of 10 HMs (i.e., Cu, +Pb, Zn, Cr, Ni, Co, Cd, As, Hg, and Mn) in the topsoil of different ecosystems in this region. The effects of four soil groups (Anthrosol, Fluvisols, Gleysol, and Alisols) and three soil texture types (sandy, clayey, and loamy soils) on the above aspects were also analyzed. Positive Matrix Factorization (PMF) models were performed to identify and quantify the potential sources and contribution rates of these HMs. Results showed that the level of HM pollution may be negligible, and there was no potential ecological risk. Of all metals, Pb and Cd exhibited the highest levels of pollution. The potential ecological risk associated with soil HMs decreased from croplands to urban and further to forests. Cu and Co were more likely to accumulate in Anthrosols, while Alisols were more likely to accumulate Pb, Cd, and Hg and had a higher overall potential ecological risk. The overall risk in clayey and loamy soils is both higher than in sandy soils. The HM accumulation in topsoil was closely related to the soil organic matter and clay contents. The potential main sources of HMs in this region can be agricultural activities, soil parent material, mining, industrial activities, and vehicle emissions. These findings suggest that special attention should be paid to soil Pb and Cd in western Dabie Mountain. Future efforts can focus on reducing mining, smelting, and industrial emissions, as well as strengthening the research on the migration patterns and mechanisms of HMs.

Yuexi County, a key tea-producing area in eastern Dabie Mountain, may face potential heavy metal(oid) (HM) contamination risks due to nearby mining and intensive agricultural activities. This study investigated seven HMs (As, Cd, Cr, Hg, Ni, Pb, and Zn) in paired soil–tea samples using multiple analytical approaches, including the geoaccumulation index (I_geo), the potential ecological risk index (RI), bioconcentration factor (BCF), and positive matrix factorization (PMF) with Monte Carlo simulation for health risk assessment. Results showed that Zn (82.65 mg/kg) and Cd (0.15 mg/kg) were the most enriched HMs in soils with higher I_geo values than other HMs. PMF analysis identified four major HM sources: mining and transportation (27.75%), agricultural activities (26.90%), natural soil parent material (26.17%), and industrial emissions (19.18%). Tea plants exhibited selective HM absorption, with Hg showing the highest bioaccumulation (BCF = 0.45), while As, Cr, and Pb had minimal uptake (BCF < 0.05). Although health risk assessments confirmed that both non-carcinogenic and carcinogenic risks from soil and tea consumption were within safe limits for adults and children, Cr and Ni required special attention due to their risk contributions. Overall, ecological and health risks in the region were found to be low. These findings provide important scientific support for pollution monitoring, risk management, and overcoming trade barriers in tea-growing regions with acidic soils. Future research should integrate HM speciation analysis with seasonal monitoring to further optimize tea plantation management strategies.

Heavy metal(oid) pollution in tea plantation has become a global concern threatening tea safety, with food safety serving as the cornerstone of the tea industry. In this study, the distribution and migration patterns of seven heavy metal(oid)s in soil-tea systems developed from three parent materials were investigated, in the geologically complex but minimally human disturbed Dabie Mountains. Results showed that although the heavy metal(oid) concentrations in tea at all sampling points meets the food safety standards of China and the European Union, significant differences existed in the bioaccumulation potential of the elements. Hg and Cd showed the highest bioconcentration factors (mean values of 0.45 and 0.33, respectively), while As, Cr, and Pb transfer were inhibited. Geological type significantly influenced the heavy metal(oid) distributions. Random forest models revealed metal-specific transfer mechanisms, with P-related variables (e.g., soil total P, available P, and microbial biomass P) and microbial C-N acquisition enzyme activities serving as key regulatory factors. This study confirms that parent materials indirectly potentially influence heavy metal(oid) bioavailability by shaping soil development and microbial functions, providing scientific basis for geology-informed food safety risk assessment in tea plantations.

Mountain–hill–plain transition zones combine terrain sensitivity, agricultural land use, and construction pressure and therefore require spatially differentiated management. This study develops a pressure-oriented framework that distinguishes composite ecological vulnerability from soil-erosion pressure and translates their multi-period co-occurrence into management demand. Using multi-source raster data for 2000, 2005, 2010, 2015, and 2020 on a common 30 m reference grid, we constructed an ecological vulnerability index (EVI) from 14 ecological, environmental, and human-activity indicators using a sensitivity–resilience–pressure framework, combined analytic hierarchy process (AHP)–entropy weighting, and unified natural breaks. Soil erosion intensity was estimated with the Revised Universal Soil Loss Equation (RUSLE) using digital elevation model (DEM)-derived flow accumulation, a capped effective slope length, and a fractional vegetation cover (FVC)-based cover-management factor. The EVI and RUSLE dimensions were integrated through a two-dimensional pressure matrix, a Coupled Pressure Index (CPI), and an Integrated Management Demand Index (IMDI). High vulnerability was concentrated in northern, urban-fringe, and selected agricultural areas, whereas moderate-or-above erosion was concentrated on slopes, in gullies, and on hilly farmland; areas subject to both pressures were spatially selective. The largest EVI weights were assigned to mean annual precipitation (0.3841), mean annual temperature (0.1727), ecosystem type (0.0820), biological abundance (0.0810), and built-up land ratio (0.0746). Non-vulnerable and slightly vulnerable areas increased from 40.62% to 64.27%, whereas highly and extremely vulnerable areas decreased from 38.98% to 23.29%. Moderate-or-above soil erosion accounted for 13.56% in 2020. The five-zone comprehensive management classification comprised stable conservation (40.19%), soil and water conservation priority (13.73%), ecological vulnerability regulation (27.94%), integrated management priority (1.48%), and transition management (16.66%). By linking ecological diagnosis, erosion-pressure identification, persistence analysis, and county-level zoning, the framework provides an interpretable spatial basis for prioritizing ecological conservation, soil and water conservation, and land-use management in mountain–hill–plain transition regions.

Understanding responses of soil organic carbon (SOC) fractions to variable hydrological conditions is essential to clarify carbon stabilization in subtropical lake wetlands. This study examined vertical and spatial variations of particulate organic carbon (POC), mineral-associated organic carbon (MAOC) and nutrient stoichiometry across four sites in Dongting Lake (0–200 cm depth, five layers). SOC and total nitrogen (TN) showed significant decreasing trends with depth from the surface to 60 cm (p < 0.05), with the highest values in the 0–40 cm layer and significantly lower values below 60 cm. In contrast, total phosphorus (TP) was vertically stable but differed greatly among sites. C/N, C/P and N/P ratios showed distinct regional disparities (p < 0.05). The proportions of POC/SOC and MAOC/SOC exhibited highly significant regional differences (p < 0.05) but no significant vertical variation or interaction effects (p > 0.05). The POC/MAOC ratio exceeded 1 only at Tuanzhou (1.62–2.20), indicating a vulnerable POC-dominated pool; other sites were MAOC-dominated (ratio < 1). Site-specific nutrient regulation further differentiated carbon pool characteristics: nutrients dominated carbon fraction variation at Tuanzhou and Huanghua, co-functioned with soil texture at Junshan, and reduced carbon stability under nutrient enrichment at West Dongting Lake. The texture control effect intensified with soil depth, and deep soil exhibited the strongest mineral protection capacity. We conclude that relative proportions of POC and MAOC in total SOC are region-specific, while their absolute concentrations decrease with depth. We recommend that wetland restoration prioritizes maintaining natural hydrological regimes and soil texture integrity, with future validation across multiple floodplain wetlands.