Multiple land-use fugacity model to assess the transport and fate of polycyclic aromatic hydrocarbons in urban and suburban areas

Soil types and land cover can significantly affect the polycyclic aromatic hydrocarbons (PAHs) environmental fate in soil compartments. Hence, estimation of the potential risk of PAHs should be carried out on a smaller scale. Herein, we proposed the multiple land-use fugacity (MLUF) model to investigate the transport and distribution of PAHs in the environment and to provide a more specific and detailed understanding of PAHs dispersion in a multiple soil compartments area. Both steady-state and dynamic MLUF model are implemented use a case study of Beijing. The results indicate that organic films have the greatest concentration of PAHs (6.19 × 103 mg/m3), while the soil and sediment phases retain the majority of PAHs (1.5 × 104 kg and 1.47 × 104 kg, respectively). The potential cancer risk associated with PAHs varies by land-use in the following order: urban green space > agricultural area > forest and semi-nature area. Additionally, the dynamic fluctuation in PAHs concentration was estimated during the COVID-19 pandemic which caused by quarantine indicates that PAH in urban green space soil compartments is more stable than other soil compartments. The present study gives a more scientific understanding of the contaminant transfer and distribution of typical volatile organic compounds in a study area with multiple soil types.

[Construction of Continuous Dynamic Model for River Networks and Its Application in Simulation of Spatiotemporal Migration of Typical Biocides].

Biocides are widely added to personal care products and enter the environment through sewage treatment plant (STP) discharge, which affects ecological health. This paper evaluated the pollution characteristics of triclosan and triclocarban in a river network during the COVID-19 epidemic. Moreover, a continuous dynamic river network model coupling a one-dimensional hydrodynamic model and four-level fugacity model was established to address the temporal and spatial heterogeneity of pollutants in the river network migration process; then, this model was applied to evaluate two biocides in the Shima River Basin. The model passed calibration and in-field concentration verification tests and yielded satisfactory simulation results. The results of the study showed that the concentration of biocides in the river network during the new crown epidemic was twice that of the non-epidemic period. The concentration of triclosan and triclocarban in the river channel first increased and then decreased with the increase of the river migration distance after STP discharge. The time variation characteristics of the concentrations were affected by the river flow. The biocide concentration in the river network of the low flow upstream area first increased and then decreased, gradually stabilizing in about 20 h. The pollution concentration in the high flow downstream area was increased, and the concentration did not stabilize at 24 h. These results indicate the necessity of evaluating the temporal and spatial characteristics of migration of typical biocides in the river network by stages and time on the premise of distinguishing the flow.