ABSTRACT
The existing methods fail to effectively utilize the viewpoint information of light field 3D images for watermark embedding which results in a serious decrease in both invisibility and robustness of the watermark. Therefore, we propose a novel, to the best of our knowledge, light field 3D dual-key-based watermarking network (3D-DKWN). Our method employs a pixel mapping algorithm to obtain the disparity sub-image of the light field 3D image and generates an encoding key (EK). Adaptive watermark embedding is then performed on the disparity sub-image and a steganographic key (SK) is generated. Finally, the light field 3D image with the embedded watermark is reconstructed. Compared with previous approaches, our method reasonably utilizes the viewpoint information of light field 3D images, resulting in the significant improvement of invisibility and robustness of the watermark.
ABSTRACT
High geogenic Mn groundwater is widespread around the world and has also proved to be harmful to human health, especially to the IQ of Children. The natural release of Mn from aquifer sediments in slightly reducing condition is believed to be the primary cause. However, there isn't enough evidence to prove that anthropogenic activities promote the reductive release of Mn. Here a Historical Petrochemical Waste Storage Site (HPWSS) was studied to evaluate its impact on groundwater quality. Significantly elevated Mn, as well as elevated TDS, anionic surfactants, and organic pollutants, were found in the shallow aquifer (9-15 m) groundwater compared to the surrounding area. The Mn was believed to be generated in-situ, while others are caused by anthropogenic pollution. The good correlations between Mn and NH4+, HCO3-, I, As, Co, V, Ti, respectively, showed the Mn mobilization was mainly attributed to the reductive dissolution of Mn oxides/hydroxides. The potential processes leading to this enhanced Mn release are discussed, including 1) the infiltration of high salinity water which solubilized sediment organic matter (OM); 2) the anionic surfactants that promoted the dissolution and mobilization of surface-derived organic pollutants as well as sediment OM. Any of these processes may have provided a C source to stimulate the microbial reduction of Mn oxides/hydroxides. This study showed the input of pollutants could change the redox and dissolution conditions of the vadose zone and aquifer, causing a secondary geogenic pollution risk in groundwater. Since Mn is easily mobilized in suboxic condition as well as its toxicity, the enhanced release due to anthropogenic perturbation merits more attention.
ABSTRACT
The potential release capacity of arsenic (As) from sediment was evaluated under a high level of exogenous organic matter (EOM) with both bioreactive and chemically reactive organic matters (OMs). The OMs were characterized by FI, HIX, BIX, and SUVA254 fluorescence indices showing the biological activities were kept at a high level during the experimental period. At the genus level, Fe/Mn/As-reducing bacteria (Geobacter, Pseudomonas, Bacillus, and Clostridium) and bacteria (Paenibacillus, Acidovorax, Delftia, and Sphingomonas) that can participate in metabolic transformation using EOM were identified. The reducing condition occurs which promoted As, Fe, and Mn releases at very high concentrations of OM. However, As release increased during the first 15-20 days, followed by a decline contributed by secondary iron precipitation. The degree of As release may be limited by the reactivity of Fe (hydro)oxides. The EOM infiltration enhances As and Mn releases in aqueous conditions causing the risk of groundwater pollution, which could occur in specific sites such as landfills, petrochemical sites, and managed aquifer recharge projects.