College of Resources and Environment, Southwest University, Chongqing 400715, China.
State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
Sci Total Environ. 2022 Jan 1;802:149865. doi: 10.1016/j.scitotenv.2021.149865. Epub 2021 Aug 24.
The heavy metal accumulation in the Tibet Plateau (TP) poses a serious ecologic risk to the health of human and the other biota. Given the TP far away from the large anthropogenic emission sources, the rapid development of traffic activities during last several decades possibly leads to the elevated heavy metal concentration in the roadside soils. Therefore, we comprehensively assessed the heavy metal distribution in the 0-5 cm and 15-20 cm depth soils located at 5 m, 50 m, and 100 m distance to the edge of two major roads among the different vegetation covers and climatic conditions in the TP to verify this hypothesis. Results show that most of heavy metal concentrations in soils of different distance to the major road display an insignificant difference. The Nemero Synthesis indexes which represent the risk of pollution for these regions almost range 1 to 2 (low pollution risk), except 12.7 (extreme pollution risk) at one site. These indicate the limited impacts from the traffic activities for the whole region, but at some specific sites with the elevated traffic pollution. The forest cover at the altitude of 3700-4100 m has the highest mercury accumulation due to the vegetation and climatic factors induced the higher atmospheric depositions and stronger complexation with the organic matters. The statistical analysis finally suggests the geogenic weathering processes, climate, terrain and vegetation play an important role in shaping heavy metal distribution along the roadside of the TP.
青藏高原（TP）的重金属积累对人类和其他生物的健康构成了严重的生态风险。鉴于 TP 远离大型人为排放源，过去几十年交通活动的快速发展可能导致路边土壤中重金属浓度升高。因此，我们综合评估了位于 TP 不同植被覆盖和气候条件下两条主要道路边缘 0-5cm 和 15-20cm 深度土壤中的重金属分布情况，以验证这一假设。结果表明，大多数距离主要道路不同距离的土壤中重金属浓度差异不显著。代表这些地区污染风险的 Nemero 综合指数几乎在 1 到 2 之间（低污染风险），只有一个地点为 12.7（极端污染风险）。这表明交通活动对整个地区的影响有限，但在一些特定地点，交通污染较高。海拔 3700-4100 米的森林覆盖区由于植被和气候因素导致大气沉降增加和与有机物更强的络合作用，汞积累最高。统计分析最终表明，地球化学风化过程、气候、地形和植被在塑造 TP 路边重金属分布方面发挥了重要作用。
