School of Geography, South China Normal University, Guangzhou, 510631, China.
School of Geography, South China Normal University, Guangzhou, 510631, China; Institute of Fundamental Research and Studies (InFeRS), Kathmandu, 44600, Nepal.
Environ Res. 2024 Jul 1;252(Pt 1):118866. doi: 10.1016/j.envres.2024.118866. Epub 2024 Apr 3.
Mercury (Hg) is known to affect aquatic, terrestrial ecosystems as well as human health, through biomagnification. Mangrove wetlands are potential Hg sinks because of their low tidal velocity, fast sedimentation rate, strong reducing condition and high organic matter content. The spatial and temporal distribution of Hg has been a hot topic of recent studies in mangrove wetlands. In this study, we investigated Hg concentration, accumulation rate and isotopes to reconstruct the Hg pollution history and to differentiate its potential sources in the Gaoqiao mangrove wetland (Guangdong province), which is part of the largest mangrove area in China. We reconstructed a first, continuous, high-resolution Hg pollution history over the last 3000 years in South China. Our findings show that mangrove wetland sediments are more enriched in Hg than the adjacent grasslands. The increased Hg concentration and δHg in recent sediments mirror the enhanced anthropogenic impacts; Hg concentrations in areas with high levels of anthropogenic disturbance are up to 5× higher than the average background value (9.9 ± 1.2 μg kg). Compared to mangroves in coastal areas of South China and around the world, the Hg concentration in Gaoqiao is much lower. The significant increase of Hg since the 1950s and the major Hg peak since the 1980s were the evidence of the human activities influences and indicated the possible start date of Anthropocene. After 2007 CE, a decline in Hg pollution occurs due to the effective implementation of the mangrove protection policy. Three potential sources were identified by the Hg isotope traces including urban gaseous Hg, industrial Hg, and regional soil and leaf litter Hg input.
汞（Hg）通过生物放大作用，对水生、陆地生态系统以及人类健康都有影响。红树林湿地由于潮汐速度低、沉积速率快、还原条件强、有机质含量高，因此是汞的潜在汇。Hg 在红树林湿地中的时空分布一直是近期研究的热点。本研究通过调查 Hg 浓度、积累率和同位素，以重建 Hg 污染历史，并区分潜在来源，从而探究中国最大的红树林区之一——广东省高桥红树林湿地的 Hg 污染历史。本研究重建了过去 3000 年来中国南方首个连续、高分辨率的 Hg 污染历史。研究结果表明，与相邻的草地相比，红树林湿地沉积物中 Hg 更为丰富。最近沉积物中 Hg 浓度和 δHg 的增加反映了人为活动的增强；人为干扰程度高的区域的 Hg 浓度比平均背景值（9.9±1.2μgkg）高 5 倍。与中国南方和世界各地沿海的红树林相比，高桥的 Hg 浓度要低得多。自 20 世纪 50 年代以来 Hg 浓度显著增加，20 世纪 80 年代以来 Hg 浓度达到峰值，这是人类活动影响的证据，表明人类世的可能开始日期。自 2007 年以来，由于有效实施了红树林保护政策，Hg 污染有所减少。Hg 同位素轨迹表明，有三个潜在的来源，包括城市气态 Hg、工业 Hg 和区域土壤和落叶 Hg 输入。
