Many studies on the bioavailability of Hg in soil–plant systems have been conducted. However, studies on the soil–tea plant system are still limited. In this study, we collected soil and tea leaf samples from 69 tea gardens in the Anxi area in China. We investigated the Hg contents in tea leaves and soil, and the bioavailability of Hg from soil to tea leaves. The results showed the following: (1) The Hg content in soil was equivalent to the background value in Fujian province and was 2.6–2.9 times higher of the national background value in China. For different geological backgrounds, the Hg contents differed. In addition, we found a negative correlation between the total Hg content and pH value (r = −0.196) and a positive correlation between total Hg and soil organic carbon (SOC) content (r = 0.116) in surface soil. (2) Compared with young leaves, Hg content in older leaves was higher. The transfer factor (TF) of Hg from soil to tea leaves ranged from 0.25% to 24.76%. (3) The correlation between Hg content in tea leaves and total Hg content in soil was not statistically significant. However, we found a statistically significant positive correlation between the Hg content in tea leaves and the extracted amount of Hg both in surface and subsurface soil. The SOC and pH value were also statistically significantly positively correlated with the Hg content in tea leaves. Our findings show that the Hg content in tea leaves does not only depend on the total Hg content in soil: it is also affected by other factors.

Soil acidification poses a substantial threat to agricultural productivity by releasing salt ions, diminishing soil fertility, and increasing susceptibility to aluminum toxicity. The aim of the study was to investigate the potential improvement of acid yellow soil through the combined application of basalt powder, lime, and polyacrylamide (PAM). Herein, 0.1 g mixed basalt powder and CaO with various proportion were added to 10 g acidic yellow soil with an initial pH of 4.16 to explore the efficient of mixed soil amendments. X-ray fluorescence (XRF) analysis of basalt powder revealed its effectiveness in supplementing soil mineral nutrients. The optimal results of reduced acidification and ion leaching of soil were obtained when the addition proportion of basalt powder to lime was 8/2 and addition ratio of PAM was 0.0002 %. The addition of mixed amendments markedly increased the pH (by up to >2.0 units) and acid-damage capacity (20.3 mmol/kg) of soil, meanwhile decreased the leaching of K⁺(58.1 %), Na⁺(42.9 %), Mg²⁺(26.3 %), and Al³⁺ (below the detectable limit) as shown by the optimal tests. The basalt powder undergoes decomposition in the soil solution, resulting in the formation of some weak acids (i.e., H₂SiO₄), the release of OH^-, and an increase in soil pH. The study reveals the underlying mechanisms of soil remediation with mixed amendment, which has potential guidance for the application of mixed soil amendment and the environment risks prediction of contaminated soil.

Soil acidification poses a substantial threat to agricultural productivity by releasing salt ions, diminishing soil fertility, and increasing susceptibility to aluminum toxicity. The aim of the study was to investigate the potential improvement of acid yellow soil through the combined application of basalt powder, lime, and polyacrylamide (PAM). Herein, 0.1 g mixed basalt powder and CaO with various proportion were added to 10 g acidic yellow soil with an initial pH of 4.16 to explore the efficient of mixed soil amendments. X-ray fluorescence (XRF) analysis of basalt powder revealed its effectiveness in supplementing soil mineral nutrients. The optimal results of reduced acidification and ion leaching of soil were obtained when the addition proportion of basalt powder to lime was 8/2 and addition ratio of PAM was 0.0002 %. The addition of mixed amendments markedly increased the pH (by up to >2.0 units) and acid-damage capacity (20.3 mmol/kg) of soil, meanwhile decreased the leaching of K⁺(58.1 %), Na⁺(42.9 %), Mg²⁺(26.3 %), and Al³⁺ (below the detectable limit) as shown by the optimal tests. The basalt powder undergoes decomposition in the soil solution, resulting in the formation of some weak acids (i.e., H₂SiO₄), the release of OH^-, and an increase in soil pH. The study reveals the underlying mechanisms of soil remediation with mixed amendment, which has potential guidance for the application of mixed soil amendment and the environment risks prediction of contaminated soil.

Soil acidification poses a substantial threat to agricultural productivity by releasing salt ions, diminishing soil fertility, and increasing susceptibility to aluminum toxicity. The aim of the study was to investigate the potential improvement of acid yellow soil through the combined application of basalt powder, lime, and polyacrylamide (PAM). Herein, 0.1 g mixed basalt powder and CaO with various proportion were added to 10 g acidic yellow soil with an initial pH of 4.16 to explore the efficient of mixed soil amendments. X-ray fluorescence (XRF) analysis of basalt powder revealed its effectiveness in supplementing soil mineral nutrients. The optimal results of reduced acidification and ion leaching of soil were obtained when the addition proportion of basalt powder to lime was 8/2 and addition ratio of PAM was 0.0002 %. The addition of mixed amendments markedly increased the pH (by up to >2.0 units) and acid-damage capacity (20.3 mmol/kg) of soil, meanwhile decreased the leaching of K⁺(58.1 %), Na⁺(42.9 %), Mg²⁺(26.3 %), and Al³⁺ (below the detectable limit) as shown by the optimal tests. The basalt powder undergoes decomposition in the soil solution, resulting in the formation of some weak acids (i.e., H₂SiO₄), the release of OH^-, and an increase in soil pH. The study reveals the underlying mechanisms of soil remediation with mixed amendment, which has potential guidance for the application of mixed soil amendment and the environment risks prediction of contaminated soil.