Abstract
Mercury is a highly toxic heavy metal pollutant, which can be detrimental to human health, yet research on soil mercury contamination in tea gardens is scarce. This work investigated the characteristics of total mercury pollution, source analysis, and health risk assessment by obtaining representative tea garden soils from 146 villages in a celebrated tea production region that is renowned for its oolong (Wulong) tea all over the world. It was found that the soils of the tea garden contained total mercury levels ranging from 0.025 to 0.296 mg/kg, with an average of 0.112 mg/kg. The analysis showed that 67.81% of the samples were free from pollution, while 31.51% exhibited no to moderate pollution, and only 0.68% were classified as moderately polluted, based on the Soil accumulation index method. The total mercury content has a strong positive relationship with total carbon content (TC), As, Na, and V (p < 0.01), as well as a significant positive correlation with Zn (p < 0.05), and a significant negative correlation with K (p < 0.05). The Positive matrix factorization (PMF) model revealed that natural sources were the major contributor to the mercury presentence in this tea production region, making up 72.4%. The likely daily intake of mercury through tea consumption in the studied region spans from 0.011 to 0.132 micrograms per kilogram of body weight per day (ug/kg bw/day), with an average intake of 0.050 ug/kg bw/day, predominantly remaining below the Hazard Quotient (HQ) threshold. The study systematically investigates the characteristics and potential hazards of soil mercury pollution in the primary Oolong tea cultivation regions, emphasizing the need for future research to assess mercury uptake in the food chain through tea consumption.