Water environment

About: Water environment is a research topic. Over the lifetime, 13384 publications have been published within this topic receiving 125138 citations.

Water Quality Prediction Method Based on IGRA and LSTM

Abstract: Water quality prediction has great significance for water environment protection A water quality prediction method based on the Improved Grey Relational Analysis (IGRA) algorithm and a Long-Short Term Memory (LSTM) neural network is proposed in this paper Firstly, considering the multivariate correlation of water quality information, IGRA, in terms of similarity and proximity, is proposed to make feature selection for water quality information Secondly, considering the time sequence of water quality information, the water quality prediction model based on LSTM, whose inputs are the features obtained by IGRA, is established Finally, the proposed method is applied in two actual water quality datasets: Tai Lake and Victoria Bay Experimental results demonstrate that the proposed method can take full advantage of the multivariate correlations and time sequence of water quality information to achieve better performance on water quality prediction compared with the single feature or non-sequential prediction methods

Superlow friction behavior of Si-doped hydrogenated amorphous carbon film in water environment

Abstract: Si-doped hydrogenated amorphous carbon (a-C:H:Si) film was prepared using hybrid radio frequency plasma-enhanced chemical vapor deposition (R.F. PECVD) and non-balanced magnetron sputtering deposition technique. The microstructure of the film was characterized by means of Raman spectrometry, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), while its friction behavior in water environment was investigated using a ball-on-disc tribometer. Results show that the a-C:H:Si film has typical diamond-like characteristics, and Si doped with a relative atomic concentration of about 3.9% in the film mainly exists in the form of Si, SiC, and SiO 2 , while it shows a superlow friction coefficient of about 0.005 in water environment when sliding against Si 3 N 4 ball. The superlow friction behavior of the hybrid diamond-like-carbon (DLC) film could be attributed to the formation of a tribochemical reaction film and boundary lubrication layer mainly consisting of colloidal silica generated from tribochemical reactions between silicides and water molecules.

Oxidative properties of FeO2+: electronic structure and solvation effects

Abstract: An electronic structure analysis is provided of the action of solvated FeO2+, [FeO(H2O)5]2+, as a hydroxylation catalyst. It is emphasized that the oxo end of FeO2+ does not form hydrogen bonds (as electron donor and H-bond acceptor) with H-bond donors nor with aliphatic C–H bonds, but it activates C–H bonds as an electron acceptor. It is extremely electrophilic, to the extent that it can activate even such poor electron donors as aliphatic C–H bonds, the C–H bond orbital acting as electron donor in a charge transfer type of interaction. Lower lying O–H bonding orbitals are less easily activated. The primary electron accepting orbital in a water environment is the 3σ*α orbital, an antibonding combination of Fe-3dz2 and O-2pz, which is very low-lying relative to the π*α compared with, for example, the σ* orbital in O2 relative to its π*. This is ascribed to relatively small Fe-3dz2 with O-2pz overlap, due to the nodal structure of the 3dz2.The H-abstraction barrier is very low in the gas phase, but it is considerably enhanced in water solvent. This is shown to be due to strong screening effects of the dielectric medium, leading to relative destabilization of the levels of the charged [FeO(H2O)5]2+ species compared to those of the neutral substrate molecules, making it a less effective electron acceptor. The solvent directly affects the orbital interactions responsible for the catalytic reaction.

Assessment of water environmental carrying capacity for sustainable development using a coupled system dynamics approach applied to the Tieling of the Liao River Basin, China

Abstract: Water environmental issues result from problems between the socio-economic system and the water environmental system. The concept of water environmental carrying capacity (WECC) can be used to describe water environmental system’s capacity which supports socio-economic development, and examine the trade-off between the driver/pressure (socio-economic) and the support (environmental) components of the societal-environmental interactive system. At the same time, an objective assessment of WECC may provide feasible integrated solutions for resolving water-related environmental problems. Hence, the quantitative assessment of WECC should be based on best available scientific knowledge coupled with appropriate simulation of complex interactions between the society and the environment. For this reason, this paper develops a WECC assessment method (WECC-SDM) which is based on a system dynamics framework. WECC-SDM can dynamically compute the WECC under different societal and environmental scenarios through coevolution and systematic simulations of the society–economy–water environment interactions. The WECC-SDM-based WECC assessment is, in fact, an interactive yet adaptive process of diagnosis–adjustment–improvement, which may provide helpful information for the sustainable development of river basins. The application of WECC-SDM shows that WECC in Tieling (in Northwest China) was severely overloaded in 2012 due to heavy ammonia nitrogen pollution in the dry season, which matches actual observations. The model was subsequently used to predict the situation of Tieling for the next 20 years. However, if positive actions in line with positive socio-economic development are taken to prevent and control pollution, it is possible for Tieling to revert back to a positive WECC situation in 2028, and support a population of 3.17 million and a GDP of 314.8 billion Yuan. As shown by the case study of Tieling, WECC-SDM can make a reasonable assessment of the current situation and simulate the trends of different scenarios, and is thus a practical WECC assessment tool.

Evaluating stream water quality through land use analysis in two grassland catchments: impact of wetlands on stream nitrogen concentration.

Abstract: We evaluated the impacts of natural wetlands and various land uses on stream nitrogen concentration in two grassland-dominated catchments in eastern Hokkaido, Japan. Analyzing land use types in drainage basins, measuring denitrification potential of its soil, and water sampling in all seasons of 2003 were performed. Results showed a highly significant positive correlation between the concentration of stream NO3-N and the proportion of upland area in drainage basins in both catchments. The regression slope, which we assumed to reflect the impact on water quality, was 24% lower for the Akkeshi catchment (0.012 +/- 0.001) than for the Shibetsu catchment (0.016 +/- 0.001). In the Akkeshi catchment, there was a significant negative correlation between the proportion of wetlands in the drainage basins and stream NO3-N concentration. Stream dissolved organic nitrogen (DON) and carbon (DOC) concentrations were significantly higher in the Akkeshi catchment. Upland and urban land uses were strongly linked to increases in in-stream N concentrations in both catchments, whereas wetlands and forests tended to mitigate water quality degradation. The denitrification potential of the soils was highest in wetlands, medium in riparian forests, and lowest in grasslands; and was significant in wetlands and riparian forests in the Akkeshi catchment. The solubility of soil organic carbon (SOC) and soil moisture tended to determine the denitrification potential. These results indicate that the water environment within the catchments, which influences denitrification potential and soil organic matter content, could have caused the difference in stream water quality between the two catchments.