Spatiotemporal distribution and inter-media transfer of polycyclic aromatic hydrocarbons in Shanghai, China: Historical patterns and future trends.

Polycyclic Aromatic Hydrocarbons (PAHs) represent pervasive pollutants, posing health risks in urban environments. It is essential to comprehend the spatiotemporal distributions, composition profiles, and inter-media transfer processes of PAHs in various environmental compartments, influenced by both natural changes and anthropogenic activities. This study integrates historical and future spatiotemporally changing environmental parameters, including climate data, GDP, population data, land-use types, and hydrological variables, into the Multimedia Urban Model (MUM). This integration enables the simulation of spatiotemporal distributions and inter-media transfer fluxes of PAHs among six different media from the 2010s to the 2100s under two distinct Shared Socio-economic Pathways (SSP) scenarios in the megacity of Shanghai, China. The MUM model, featuring diverse gridded parameters, effectively captures PAH concentrations and movement across environmental compartments. Results indicate a decreasing trend in PAHs concentrations in the 2100s compared to the 2010s, with PAH concentrations in water, sediment, vegetation, and organic film covering impermeable surfaces under the SSP3-7.0 scenario higher than those of the SSP1-2.6 scenario. Low molecular weight PAHs dominate in the sediment, water, and air, whereas high molecular weight PAHs prevail in the organic film, vegetation, and soil. Sediment and soil serve as the predominant sinks for PAHs. The primary transport processes for PAH movement include air-film, air-soil, film-water, soil-air, and water-air. Almost all transfer fluxes exhibit a declining trend in future periods except for the air-film transport pathway. The principal input and removal routes for PAHs in Shanghai involve the advection of air and water. The study provides essential insights into the environmental behavior of PAHs and informs targeted pollution control in Shanghai. Additionally, it serves as a technical reference for similar pollution prediction research.

Environmental fate and health risks of polycyclic aromatic hydrocarbons in the Yangtze River Delta Urban Agglomeration during the 21st century.

Understanding the spatiotemporal distribution and behavior of Polycyclic Aromatic Hydrocarbons (PAHs) in the context of climate change and human activities is essential for effective environmental management and public health protection. This study utilized an integrated simulation system that combines land-use, hydrological, and multimedia fugacity models to predict the concentrations, transportation, and degradation of 16 priority-controlled PAHs across six environmental compartments (air, water, soil, sediment, vegetation, and impermeable surfaces) within one of the world's prominent urban agglomerations, the Yangtze River Delta Urban Agglomeration (YRDUA), under future Shared Socio-economic Pathways (SSP)-Representative Concentration Pathways (RCP) scenarios. Incremental lifetime carcinogenic risk for adults and children exposed to PAHs were also evaluated. The results show a declining trend in PAHs concentrations and associated health risks during the 21st century. Land use types, hydrological characteristics, population, and GDP, have significant correlations with the fate of PAHs. The primary removal for PAHs is determined to be driven by advection through air and water. PAHs covering on impermeable surfaces pose a relatively higher health risk compared to those in other environmental media. This study offers valuable insights into PAHs pollution in the YRDUA, aiming to ensure public health safety, with the potential for application in other urban areas.

Identifying cadmium and lead co-accumulation from living rice blade spectrum.

Neither cadmium (Cd) nor lead (Pb) is necessary for crop growth, but they both can accumulate in soil and crop tissues, resulting in land degradation and crop reduction. Few researchers have explored how to detect Cd-Pb co-accumulation in leaves using proximal sensing techniques, especially by low-cost, easy-to-use leaf clips that capture hyperspectral reflections at suitable foliar positions. In this study, a hyperspectral imager was employed to collect images of the rice canopy from a designed greenhouse experiment that included 16 pretreatments of Cd-Pb co-accumulation, followed by spectral extractions from 3 foliar positions: the blade root, the middle of the leaf, and the leaf apex. A support vector machine with leave-one-out cross-validation was performed to diagnose the contaminative levels based on the feature wavelengths selected by an improved successive projection algorithm. Partial least squares regression was used to predict Cd-Pb concentrations in rice blades. The results indicated that diagnostic accuracies were varied using spectra of different foliar positions. The blade root and leaf apex of rice blades were the optimal foliar position for detecting Cd and Pb contamination, respectively. At the optimal foliar positions, diagnostic accuracies exceeded 0.80 for distinguishing whether the rice is subject to Cd-Pb contamination. The Cd prediction performed 'very good' with a residual prediction deviation (RPD) of 2.21, a R2 of 0.79, and a root mean square error (RMSE)of 6.14, while that of Pb was 1.62, 0.61, and 186.54. Important wavelengths were identified at 659-694 nm and 667-694 nm to detect Cd and Pb contamination. In summary, our results verified the feasibility and clarified the optimal foliar positions of rice blades to detect Cd-Pb contamination. The wavelengths selecting have the great potential in the design of future leaf clips, and the optimal foliar position can provide suggestions to improve diagnostic performances in field applications.

[Tempo-spatial Variations and Influential Factors of Carbon Dioxide Emissions from the Geheyan Reservoir over the Qingjiang River Basin, China].

Greenhouse gas emission from aquatic ecosystem will affect climate change on the regional and global scale. So large river interception project which affects the carbon cycle model and greenhouse gas emission from aquatic ecosystem has provoked more and more attentions in recent years. In order to understand and evaluate the effects of typical hydropower project construction on the aquatic ecosystem and carbon cycle, the Geheyan Reservoir, a typical river interception project, was selected as a typical case in this paper for measuring carbon dioxide fluxes from interface between water and atmosphere from March, 2015 to February, 2016. The integration of the online gas analyzer and floating box was used to obtain carbon dioxide fluxes from interface between water and atmosphere. Data was obtained over the before dam, upstream, tributary, drawdown area and bay area respectively for understanding the spatial Heterogeneity of carbon dioxide fluxes. Data analysis showed that yearly mean fluxes of carbon dioxide from the Geheyan Reservoir was (55.6918±66.3329) mg·(m2·h)-1 during measurement, which indicated that the temporal distribution was higher in winter and lower in other seasons and the spatial variation was higher in typical bay and lower before dam as well as drawdown zone over the reservoir. Moreover, the seasonal variation of carbon dioxide fluxes from the interface between water and atmosphere was very stable at Yuxiakou measurement points as a typical background area of the reservoir, which was unexpectedly higher than those before dam and drawdown zone in the most months during measurement. The results from data analysis also indicated that the spatial and temporal variation of carbon dioxide fluxes from the Geheyan Reservoir was affected by water quality parameters such as dissolved oxygen, chlorophyll, pH, water temperature and conductivity and carbon in water, but the relationship between carbon dioxide fluxes and other parameter was very different within each season and impound period. So the results above will provide more supports for understanding the import pathway and transfer of aquatic carbon cycle caused by large river interception project in China.