A typical petrochemical industrial area was selected as the research object, and particulate phase and gas phase samples of intermediate-volatility organic compounds (IVOCs) were collected in the air of the plant area in summer (July and August in 2021) to explore the pollution characteristics of IVOCs emission from petrochemical industrial sources and estimate their corresponding SOA (secondary organic aerosols) formation potential. The results show that, 1) the average concentration of IVOCs particle phase in typical petrochemical area is 4.22±1.54 μg/m³, and the average concentration of IVOCs gas phase is 108.87±78.93 μg/m³. The average concentration of IVOCs during the day is higher than that at night both in the gas phase and in the particle phase. 2) The n-alkanes in gas phase are concentrated from C₁₂ to C₂₂, while the n-alkanes in particle phase are concentrated from C₂₂ to C₃₅. The gas phase of polycyclic aromatic hydrocarbons is concentrated in naphthalene and phenanthrene, and the particle phase is concentrated in fluorene. 3) The IVOCs in the petrochemical industrial zone are quantitatively disassembled. The concentration is mainly concentrated in the interval B₁₈–B₂₁. The mass concentration sum of these four zones accounts for 60.41% of the total mass of IVOCs.

In order to know well the range and degree of gas hydrate dissociation during the large-scale exploitation of marine natural gas hydrate, the finite element software COMSOL is used to simulate the electromagnetic monitoring of the natural gas hydrate exploitation through the downhole controlled-source electromagnetic (CSEM) method. By constructing the 3D formation model containing the high-resistivity hydrate reservoir layer, the comparison between the downhole vertical source and the conventional towed horizontal source indicates that the former has advantages on the electric field responses for small source-receiver offsets required for monitoring. Then, the influence of vertical source monitoring system parameters, such as metal casing, vertical source depth, emission frequency, observation errors and noises, on the seafloor electric field responses are analyzed. The simulation results show that the metal casing, vertical source depth and emission frequency have significant influences on the seafloor electric field responses, and especially for the existence of metal casing, the vertical source should be placed below the hydrate reservoir and the low frequency such as 1 Hz of emission electrical current should be considered. The observation errors and noises of the monitoring system would not significantly affect the performance of the monitoring system with metal casing under the condition of small offsets. When the production range of the hydrate reservoir increases, the downhole vertical source monitoring system ensures that seafloor receivers can detect the electric field changes caused by hydrate exploitation and effectively identify the lateral boundary of production area. Hence, it is feasible to use the downhole CSEM method to monitor the dynamic reservoir process during marine hydrate exploitation.