| 长江与黄河源丰水期地表水中汞的分布特征、赋存形态及来源解析 |
| 摘要点击 2806 全文点击 1748 投稿时间：2022-01-16 修订日期：2022-03-11 |
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| 中文关键词 三江源 汞浓度 空间分布 形态特征 源解析 |
| 英文关键词 Three Rivers Source region mercury concentration spatial distribution species characteristic source analysis |
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| 中文摘要 |
| 在全球变暖的背景下，探明青藏高原地表水中汞的形态、分布和来源特征对认识高寒地区汞的生物地球化学循环过程具有重要意义.为探讨汞在高寒地区地表水中的分布特征和潜在来源，以青藏高原长江源和黄河源流域地表水为研究对象，测定丰水期地表水中总汞（THg）、颗粒态汞（PHg）和溶解态汞（DHg）的浓度，分析其空间分布特征及其影响因素，并利用PMF模型定量解析地表水中汞的来源.结果表明，长江源和黄河源流域地表水中ρ（DHg）均值分别为（2.96±1.26） ng ·L-1和（2.47±0.83） ng ·L-1，二者无显著差异；而长江源流域地表水中ρ（THg）［（10.69±11.14） ng ·L-1］和ρ（PHg）［（8.46±11.41） ng ·L-1］显著高于黄河源流域地表水中的ρ（THg）［（3.37±2.03） ng ·L-1］和ρ（PHg）［（1.13±1.02） ng ·L-1）］（P<0.05）.此外，考虑到较低的汞浓度水平和甲基化程度，研究区内汞的生态威胁较弱.相关性分析结果显示，长江源流域地表水中汞以PHg为主要形态，其浓度变化主要受冰川融水输入、土壤侵蚀和降水等因素影响；DHg作为黄河源流域地表水中汞的主要形态，其分布格局主要受制于汞和溶解性有机质（DOC）的结合作用.空间分布上，河道坡降和土壤侵蚀强度的空间差异可能是导致长江源流域地表水中THg和PHg浓度随水流方向总体呈下降趋势的关键因素.PMF模型解析结果表明，长江源和黄河源区地表水中51.4%的汞来源于大气沉降，38.8%的汞来源于水流对土壤岩层或沉积物的侵蚀作用，而9.7%的汞来源于土壤径流或渗流的输入. |
| 英文摘要 |
| To understand the mercury (Hg) biogeochemical cycle in alpine regions under global warming, it is critical to identify the distribution and sources of Hg in aquatic ecosystems of the Tibet Plateau. The spatial distribution pattern and potential sources of Hg species including total mercury (THg), particulate mercury (PHg), and dissolved mercury (DHg) were investigated in surface waters of the Yangtze and Yellow River source basins during the wet season. The results showed that average ρ(DHg) in surface water of the Yangtze and Yellow River source basins were comparable[(2.96±1.26) ng·L-1 and (2.47±0.83) ng·L-1, respectively], whereas the average ρ(THg)[(10.69±11.14) ng·L-1] and ρ(PHg)[(8.46±11.41) ng·L-1] in the source basin of the Yangtze River were significantly higher than that in surface water of the Yellow River source basin[(3.37±2.03) ng·L-1 and (1.13±1.02) ng·L-1, respectively]. It is worth noting that the ecological risk of Hg in the study area was limited because of low Hg concentration and methylation level. In addition, the correlation analysis illustrated that the THg was mainly concentrated by PHg in the source basin of the Yangtze River. Specifically, the concentration variations in Hg were mainly affected by the input of glacier meltwater, soil erosion, and precipitation. By contrast, the main species of Hg in the source basin of the Yellow River was DHg, the distribution pattern of which was mainly controlled by DOC. Spatially, a significant negative correlation was found between ρ(PHg) and longitude in the source basin of the Yangtze River (R2=0.46, P<0.01). The spatial distribution differences of river slope and soil erosion intensity were identified as the key factors leading to the decreasing trend of ρ(PHg) and ρ(THg) along the river flow in the source basin of the Yangtze River. The results of the PMF model further demonstrated that in the surface waters of the source regions of the Yangtze and Yellow Rivers, 51.4% of Hg derived from long-distance atmospheric deposition, 38.8% from erosion of soil rock or sediment via stream flow, and 9.7% from soil runoff or seepage input. |
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