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Water environment

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


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Journal ArticleDOI
TL;DR: In this article, a methodology was developed for quantifying the effects of grazing intensities using the normalized difference vegetation index (NDVI) obtained by the moderate resolution imaging spectroradiometer (MODIS) on-board the earth observing system (EOS) terra satellite.

210 citations

Journal ArticleDOI
TL;DR: Aquatic weeds seem to be a promising biosorbent for the removal of chromium ions from water environment with significant difference in the concentrations of Cr(VI) and total chromium removed by the biosorbents.

209 citations

Journal ArticleDOI
TL;DR: This study represented a systematical evaluation regarding the transformation process of FLU by PS, and showed that the heterogeneous catalysts can efficiently activate PS for FLU removal from the water environment.

205 citations

Journal ArticleDOI
TL;DR: This method is the least computationally intensive one that can give accurate stabilization energies for all common classes of noncovalent interactions (aromatic-aromatic, H-bonding, ionic, halogen bonding, charge-transfer, etc.) and allows for direct comparison of binding energies between different interaction types.
Abstract: Aromatic systems contain both σ- and π-electrons, which in turn constitute σ- and π-molecular orbitals (MOs). In discussing the properties of these systems, researchers typically refer to the highest occupied and lowest unoccupied MOs, which are π MOs. The characteristic properties of aromatic systems, such as their low ionization potentials and electron affinities, high polarizabilities and stabilities, and small band gaps (in spectroscopy called the N → V1 space), can easily be explained based on their electronic structure. These one-electron properties point to characteristic features of how aromatic systems interact with each other. Unlike hydrogen bonding systems, which primarily interact through electrostatic forces, complexes containing aromatic systems, especially aromatic stacked pairs, are predominantly stabilized by dispersion attraction. The stabilization energy in the benzene dimer is rather small (~2.5 kcal/mol) but strengthens with heteroatom substitution. The stacked interaction of aromatic nucleic acid bases is greater than 10 kcal/mol, and for the most stable stacked pair, guanine and cytosine, it reaches approximately 17 kcal/mol. Although these values do not equal the planar H-bonded interactions of these bases (~29 kcal/mol), stacking in DNA is more frequent than H-bonding and, unlike H-bonding, is not significantly weakened when passing from the gas phase to a water environment. Consequently, the stacking of aromatic systems represents the leading stabilization energy contribution in biomacromolecules and in related nanosystems. Therefore stacking (dispersion) interactions predominantly determine the double helical structure of DNA, which underlies its storage and transfer of genetic information. Similarly, dispersion is the dominant contributor to attractive interactions involving aromatic amino acids within the hydrophobic core of a protein, which is critical for folding. Therefore, understanding the nature of aromatic interactions, which depend greatly on quantum mechanical (QM) calculations, is of key importance in biomolecular science. This Account shows that accurate binding energies for aromatic complexes should be based on computations made at the (estimated) CCSD(T)/complete basis set limit (CBS) level of theory. This method is the least computationally intensive one that can give accurate stabilization energies for all common classes of noncovalent interactions (aromatic-aromatic, H-bonding, ionic, halogen bonding, charge-transfer, etc.). These results allow for direct comparison of binding energies between different interaction types. Conclusions based on lower-level QM calculations should be considered with care.

204 citations

Journal ArticleDOI
01 Jan 1967-Oikos
TL;DR: It is concluded that in many areas human activities has raised the mercury content of the environment far above the natural levels.
Abstract: Activation analysis of mercury content in axial musculature of pike (Esox lucius) has been used in the present study as a means of estimating the level of mercury present in the water environment. The concentration factor from water to pike is of the order 3000 or more. The relation between mercury content and weight and age of fish specimens is discussed. By a graphical method the values for mercury content for specimens representing 1 kilogram of weight have been calculated for a number of localities and used for geographical comparison. The effect of industrial contamination is demonstrated by a comparison of mercury content of samples of pike from above and below localities, where emission of waste water containing mercury takes place. There are strong indications that mercury appears also as an airborne pollution affecting the water environment. A number of sources of mercury contamination are discussed. It is concluded that in many areas human activities has raised the mercury content of the environment far above the natural levels. Pe3loMe

203 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202239
2021932
2020869
2019980
20181,015
2017916