Soil erosion on highway side-slope has been recognized as a cause of environmental damage and a potential threat to road embankments in the high-altitude permafrost regions.To assess the risk to roads and to protect t...Soil erosion on highway side-slope has been recognized as a cause of environmental damage and a potential threat to road embankments in the high-altitude permafrost regions.To assess the risk to roads and to protect them effectively,it is crucial to clarify the mechanisms governing roadside erosion.However,the cold climate and extremely vulnerable environment under permafrost conditions may result in a unique process of roadside erosion,which differs from the results of current studies conducted at lower altitudes.In this study,a field survey was conducted to investigate side-slope rill erosion along the permafrost section of a highway on the Qinghai‒Tibet Plateau of China.Variations in erosion rates have been revealed,and intense erosion risks(with an average erosion rate of 13.05 kg/m^(2)/a)have been identified on the northern side of the Tanggula Mountains.In the case of individual rills,the detailed rill morphology data indicate that the rill heads are generally close to the slope top and that erosion predominantly occurs in the upper parts of highway slopes,as they are affected by road surface runoff.In the road segment scale,the Pearson correlation and principal component analysis results revealed that the protective effect of vegetation,which was influenced by precipitation,was greater than the erosive effect of precipitation on roadside erosion.A random forest model was then adopted to quantify the importance of influencing factors,and the slope gradient was identified as the most significant factor,with a value of 0.474.Accordingly,the integrated slope and slope length index(L0.5S2)proved to be a reliable predictor,and a comprehensive model was built for highway side-slope rill erosion prediction(model efficiency=0.802).These results could be helpful for highway side-slope conservation and ecological risk prediction in alpine permafrost areas.展开更多
In this study sediment samples were collected from 13 sites of Haihe River in Tianjin City, China, sixteen of priority polycyclic aromatic hydrocarbons （PAHs） listed in USEPA were analyzed by means of GC-MS. The tot...In this study sediment samples were collected from 13 sites of Haihe River in Tianjin City, China, sixteen of priority polycyclic aromatic hydrocarbons （PAHs） listed in USEPA were analyzed by means of GC-MS. The total concentrations of PAH ranged from 774.81 to 255371.91 ng/g dw, and two to four rings of PAHs were dominant in sediment samples. Molecular ratios, such as phenanthrene/anthracene, fluoranthene/pyrene and low-molecular-weight PAH/high-molecular-weight PAH, were used to study the possible sources of pollution. It indicated a mixed pattern of parolytic and petrogenic inputs of PAHs in sediments in Haihe River. The petrogenic PAHs may be mainly derived from the leakage of refined products, e.g., gasoline, diesel fuel and fuel oil vehicle traffics or gas stations from urban area. The pyrolytic PAHs might be from the discharge of industrial wastewater and the emission of atmospheric particles from petrochemical factories. In addition, the levels of PAHs in the urban and industrial areas are far beyond the values reported from other rivers and marine systems reported. This situation may be due to polluted discharging from some petrochemical industrial manufactories and worse traffic conditions in Tianjin.展开更多
基金funded by the Second Tibetan Plateau Scientific Expedition and Research(STEP),grant number 2021QZKK0203the National Key Research and Development Program of China,grant number 2021YFB2600105.
文摘Soil erosion on highway side-slope has been recognized as a cause of environmental damage and a potential threat to road embankments in the high-altitude permafrost regions.To assess the risk to roads and to protect them effectively,it is crucial to clarify the mechanisms governing roadside erosion.However,the cold climate and extremely vulnerable environment under permafrost conditions may result in a unique process of roadside erosion,which differs from the results of current studies conducted at lower altitudes.In this study,a field survey was conducted to investigate side-slope rill erosion along the permafrost section of a highway on the Qinghai‒Tibet Plateau of China.Variations in erosion rates have been revealed,and intense erosion risks(with an average erosion rate of 13.05 kg/m^(2)/a)have been identified on the northern side of the Tanggula Mountains.In the case of individual rills,the detailed rill morphology data indicate that the rill heads are generally close to the slope top and that erosion predominantly occurs in the upper parts of highway slopes,as they are affected by road surface runoff.In the road segment scale,the Pearson correlation and principal component analysis results revealed that the protective effect of vegetation,which was influenced by precipitation,was greater than the erosive effect of precipitation on roadside erosion.A random forest model was then adopted to quantify the importance of influencing factors,and the slope gradient was identified as the most significant factor,with a value of 0.474.Accordingly,the integrated slope and slope length index(L0.5S2)proved to be a reliable predictor,and a comprehensive model was built for highway side-slope rill erosion prediction(model efficiency=0.802).These results could be helpful for highway side-slope conservation and ecological risk prediction in alpine permafrost areas.
文摘In this study sediment samples were collected from 13 sites of Haihe River in Tianjin City, China, sixteen of priority polycyclic aromatic hydrocarbons （PAHs） listed in USEPA were analyzed by means of GC-MS. The total concentrations of PAH ranged from 774.81 to 255371.91 ng/g dw, and two to four rings of PAHs were dominant in sediment samples. Molecular ratios, such as phenanthrene/anthracene, fluoranthene/pyrene and low-molecular-weight PAH/high-molecular-weight PAH, were used to study the possible sources of pollution. It indicated a mixed pattern of parolytic and petrogenic inputs of PAHs in sediments in Haihe River. The petrogenic PAHs may be mainly derived from the leakage of refined products, e.g., gasoline, diesel fuel and fuel oil vehicle traffics or gas stations from urban area. The pyrolytic PAHs might be from the discharge of industrial wastewater and the emission of atmospheric particles from petrochemical factories. In addition, the levels of PAHs in the urban and industrial areas are far beyond the values reported from other rivers and marine systems reported. This situation may be due to polluted discharging from some petrochemical industrial manufactories and worse traffic conditions in Tianjin.
