Search Results (2)

The study investigated the composition and content of Σ₁₅PAH in the surface and core sediments from Dachan Bay (DCB) in Shenzhen city and discussed the effects of urban development and regional energy structure on the marine environment through the spatial distribution, vertical profile, and sources of Σ₁₅PAH. The results indicated that the concentrations of Σ₁₅PAH in the sediments of DCB ranged between 299 ng/g and 2336 ng/g in the surface sediments and between 65 ng/g and 994 ng/g in the core sediments. The horizontal spatial distribution of PAHs content with decreasing concentrations from the coastal to central areas implied the land-based input of PAHs. The vertical profile of high PAHs concentration in 0 cm–60 cm suggested that the PAHs pollution is attributed to the urban development of Shenzhen since 1950, especially after the 1980s. According to features of the low molecular weight (LMW)/high molecular weight (HMW), PAHs diagnostic ratios and their relationships with total organic carbon (TOC) and oil, the pyrogenic PAHs were mainly from the combustion of petroleum and byproducts in the surface and 0 cm–60 cm sediments but from the combustion of biomass in 60 cm–190 cm sediments, which corresponded with the variation of energy structure in surrounding areas. This study suggested that urban development and regional energy structure have a great impact on PAHs distribution in DCB and further controls of land-based pollutant emissions are still needed. Full article

The Pearl River Delta in South China is subject to severe eutrophication, which is significantly exacerbated by the total nitrogen (TN). Remote sensing technology with large-scale synchronous observations in the Pearl River Delta can effectively monitor organic pollution. Statistical methods based on remote sensing images have been widely used in water quality parameter retrieval for inland rivers, reservoirs, and lakes, but have seldom been applied in the Pearl River Delta. TN is also a non-optically active substance, so it is difficult to retrieve TN through analysis methods. This study retrieves the concentration of total nitrogen (TN) based on Landsat8 images of the Pearl River Delta using a statistical method. The stepwise regression function is built by analyzing the TN concentration and the single-band, two-band, and three-band spectral information groups measured by an ASD FieldSpec3 spectrometer. The retrieval results show that the proposed method performs well with a small mean absolute error (MAE) (0.36 mg/L for TN) and high agreement (R² = 0.61 for TN) between the in situ data and the retrieval concentration. The results demonstrate that the concentration of TN in the east of the Pearl River Delta was higher than in the west. Dachan Bay and Shenzhen Bay had the highest TN concentrations, which were around 3.02 mg/L and 3.67 mg/L. The 750–850 nm band could be an important reference for further exploring the spectral characteristics and retrieval of TN. The retrieval method in this study is easy to implement and convenient for local TN distribution capture, which can provide a timely reference for daily water quality supervision and management in the Pearl River Delta. Full article