Key Laboratory of Bio-resources and Eco-environment (Ministry of Education), College of Life Science, Sichuan University, Chengdu, Sichuan, China.
Environ Monit Assess. 2018 Mar 7;190(4):197. doi: 10.1007/s10661-018-6567-9.
Railway transportation is an important transportation mode. However, railway transportation causes heavy metal pollution in surrounding soils. Heavy metal pollution has a serious negative impact on the natural environment, including a decrease of enzyme activities in soil and degradation of sensitive ecosystems. Some studies investigated the heavy metal pollution at railway stations or certain transportation hubs. However, the pollution accumulated in artificial cut slope soil all along the rails is still questioned. The interest on non-point source pollution from railways is increasing in an effort to protect the soil quality along the line. In this study, we studied spatial distributions of heavy metals and five enzyme activities, i.e., urease (UA), saccharase (SAC), protease (PRO), catalase (CAT), and polyphenol oxidase (POA) in the soil, and the correlation among them beside three different railways in Sichuan Province, China, as well. Soil samples were respectively collected from 5, 10, 25, 50, 100, and 150 m away from the rails (depth of 0-8 cm). Results showed that Mn, Cd, Cu, and Zn were influenced by railway transportation in different degrees while Pb was not. Heavy metal pollution was due to the abrasion of the gravel bed as well as the tracks and freight transportation which caused more heavy metal pollution than passenger transportation. Enzymatic activities were significantly negatively correlated with heavy metals in soils, especially Zn and Cu. Finally, it is proposed that combined use of PRO and POA activities could be an indicator of the heavy metal pollution in cut slope soils. The protective measures aimed at heavy metal pollution caused by railway transportation in cut slope soils are urgent.
铁路运输是一种重要的运输方式。然而，铁路运输会导致周围土壤中的重金属污染。重金属污染对自然环境有严重的负面影响，包括土壤中酶活性的降低和敏感生态系统的退化。一些研究调查了火车站或某些运输枢纽的重金属污染。然而，铁轨沿线人工切坡土壤中积累的重金属污染仍存在疑问。为了保护沿线土壤质量，人们对铁路的非点源污染越来越感兴趣。本研究以中国四川省的三条不同铁路为例，研究了重金属及脲酶（UA）、蔗糖酶（SAC）、蛋白酶（PRO）、过氧化氢酶（CAT）和多酚氧化酶（POA）等五种土壤酶活性在土壤中的空间分布及其相关性。分别在距铁轨 5、10、25、50、100 和 150 m 处（0-8 cm 深）采集土壤样品。结果表明，Mn、Cd、Cu 和 Zn 不同程度地受到铁路运输的影响，而 Pb 则没有。重金属污染是由于砾石道床以及轨道和货运运输造成的，比客运运输造成了更多的重金属污染。土壤中重金属与酶活性呈显著负相关，尤其是 Zn 和 Cu。最后提出，PRO 和 POA 活性的联合使用可以作为切坡土壤重金属污染的指标。针对铁路运输引起的切坡土壤重金属污染的防护措施迫在眉睫。
