Floating Bi–N–TiO2 photocatalysts were synthesized using a novel sol–gel method grafted on expanded graphite C/C composites with high adsorption capacity and photocatalytic activity. The Bi–N–TiO2/EGC were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), the N2 adsorption/desorption method (BET), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), and X-ray photoelectron spectroscopy (XPS). The SEM and XRD results revealed that all the composites had with mesoporous structures; the crystalline phases were mainly influenced by calcination temperature and anatase transformed into rutile at 800 °C. The N2 adsorption/desorption method (BET) indicated that the specific surface area and pore size could be changed through adjusting the calcination temperature and Bi dosage. All Bi modified N–TiO2 composites exhibited higher photocatalytic activity for degradation of diesel (≥53.7%) than N–TiO2 under visible light irradiation. The composite Bi1.0–N–TiO2/EGC calcined at 550 °C with evenly distributed TiO2 exhibited the highest activity (83.8%), which was attributed to the high surface area, red shift of absorptive light to visible light as well as improved efficient charge separation. The results of influence experiments, under different conditions of pH, salinity, emulsifier and humic acid, also evidenced that Bi–N–TiO2/EGC composites are stable catalysts for the in situ remediation of diesel contaminated water.

As a proxy to trace the impact of anthropogenic activity, sedimentary polycyclic aromatic hydrocarbons (PAHs) are compared between the early industrialized and newly industrialized countries of Germany and China, respectively. Surface sediment samples in the Ammer River of Germany and the Liangtan River of China were collected to compare concentration levels, distribution patterns, and diagnostic plots of sedimentary PAHs. Total concentrations of 16 PAHs in Ammer sediments were significantly higher by a factor of ∼4.5 than those in Liangtan. This contrast agrees with an extensive literature survey of PAH levels found in Chinese versus European sediments. Distribution patterns of PAHs were similar across sites in the Ammer River, whereas they were highly varied in the Liangtan River. Pyrogenic sources dominated in both cases. Strong correlations of the sum of 16 PAHs and PAH groups with TOC contents in the Liangtan River may indicate coemission of PAHs and TOC. Poor correlations of PAHs with TOC in the Ammer River indicate that other factors exert stronger influences. Sedimentary PAHs in the Ammer River are primarily attributed to input of diffuse sources or legacy pollution, while sediments in the Liangtan River are probably affected by ongoing point source emissions. Providing further evidence of a more prolonged anthropogenic influence are the elevated black carbon fractions in sedimentary TOC in the Ammer compared to the Liangtan. This implies that the Liangtan River, like others in newly industrialized regions, still has a chance to avoid legacy pollution of sediment which is widespread in the Ammer River and other European waterways.