Terrestrial humic substances induce photodegradation of polysaccharides in the aquatic environment

The Dnipro river is the main catchment in Ukraine. Within its territory the river flow is regulated and &#160;represents a cascade of six reservoirs in direction from upper to down: Kyiv, &#160;Kanevsky, Kremenchug, Kamensky, Dniprovsky, and Kakhovsky. &#160;Reservoirs have a total water mirror area of 6950 km&#178; and a total water volume of 44 km&#179;. These figures make 95% and 91% of the total number of all large reservoirs in Ukraine, respectively. Their location in various natural and climatic zones, the difference in morphometric and hydrodynamic characteristics, hydrobiological, physicochemical, and sedimentation processes, as well as levels of anthropogenic load make them a unique object for studying intra-water processes, including processes of transformation, interphase exchange and accumulation of heavy metals in bottom sediments.The study presents long-term data on the dynamics of the content and patterns of distribution of heavy metals (Fe, Mn, Cu, Zn, Pb, Ni, Co, Cd) in water, as well as in suspended solids, and bottom sediments of these reservoirs.The influence of hydrological factors, physicochemical and hydrobiological processes on the nature of the transformation and interphase distribution of the heavy metals in the system &#8220;water &#8211; suspended substances &#8211; bottom sediments&#8221; has been shown. The contribution of mineral particles, Fe hydroxides and Mn oxides, and high molecular weight fractions of humic substances (humic and fulvic acids) on sorption processes and the removal of heavy metals from the solution phase were studied.It has been found that the shift of the equilibrium of the calcium-carbonate system towards the formation of the CaCO3 solid phase, which is associated with intensive hydrobiological processes in the Kremenchug and Kakhovsky reservoirs, leads to the additional removal of heavy metals from the solution due to deposition.The study reveals the special aspects of the interphase distribution of heavy metals between the liquid and solid phases, due to the physicochemical conditions of the aquatic environment, as well as the morphometric characteristics of the reservoirs, flow rate, water temperature, duration of the ice cover during winter, and the content of organic substances.The results of the distribution of heavy metals among various types of bottom sediments and their different particle size fractions are presented.&#160;It has been shown that a specific feature of the first in the cascade Kyiv Reservoir is the high content of dissolved humic substances, which play an important role in the migration of heavy metals.The co-existing forms of metals in the solution phase are investigated with the thermodynamic modeling approach. This method was also used to evaluate the flow of metals from pore solutions of bottom sediments into the aquatic environment. Differences in the rate of molecular diffusion of metals from bottom sediments have been shown. They are caused by both the water chemistry and pore solutions, and the concentrations of metals and binding ligands.The levels of anthropogenic load with heavy metals on the reservoir ecosystems have been evaluated over the past 30 years.

Download Full-text

Methylation of mercury by humic substances in an aquatic environment

The Science of The Total Environment ◽

10.1016/0048-9697(82)90082-1 ◽

1982 ◽

Vol 25 (2) ◽

pp. 133-142 ◽

Cited By ~ 70

Author(s):

Hisamitsu Nagase ◽

Youki Ose ◽

Takahiko Sato ◽

Tetsuya Ishikawa

Keyword(s):

Humic Substances ◽

Aquatic Environment

Download Full-text

The contradictory biological behavior of humic substances in the aquatic environment

Humic Substances in the Aquatic and Terrestrial Environment - Lecture Notes in Earth Sciences ◽

10.1007/bfb0010488 ◽

1991 ◽

pp. 367-390 ◽

Cited By ~ 2

Author(s):

Robert C. Petersen

Keyword(s):

Humic Substances ◽

Aquatic Environment ◽

Biological Behavior

Download Full-text

Electron Microscopy in the Study of Natural Phytoplankton Assemblages

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100119831 ◽

1985 ◽

Vol 43 ◽

pp. 620-623

Author(s):

Linda Sicko-Goad

Keyword(s):

Electron Microscopy ◽

Aquatic Environment ◽

Size Range ◽

Physical Parameters ◽

Specific Information ◽

Phytoplankton Assemblages ◽

Phytoplankton Productivity ◽

Ecosystem Effects ◽

Time Of Year ◽

Species Specific

Although the use of electron microscopy and its varied methodologies is not usually associated with ecological studies, the types of species specific information that can be generated by these techniques are often quite useful in predicting long-term ecosystem effects. The utility of these techniques is especially apparent when one considers both the size range of particles found in the aquatic environment and the complexity of the phytoplankton assemblages.The size range and character of organisms found in the aquatic environment are dependent upon a variety of physical parameters that include sampling depth, location, and time of year. In the winter months, all the Laurentian Great Lakes are uniformly mixed and homothermous in the range of 1.1 to 1.7°C. During this time phytoplankton productivity is quite low.

Download Full-text

Lycopene alleviates sulfamethoxazole-induced hepatotoxicity in grass carp (Ctenopharyngodon idellus) via suppression of oxidative stress, inflammation and apoptosis

Food & Function ◽

10.1039/d0fo01638a ◽

2020 ◽

Vol 11 (10) ◽

pp. 8547-8559

Author(s):

Hongjing Zhao ◽

Yu Wang ◽

Mengyao Mu ◽

Menghao Guo ◽

Hongxian Yu ◽

...

Keyword(s):

Oxidative Stress ◽

Secondary Metabolites ◽

Human Health ◽

Grass Carp ◽

Aquatic Environment ◽

Ctenopharyngodon Idellus

Antibiotics are used worldwide to treat diseases in humans and other animals; most of them and their secondary metabolites are discharged into the aquatic environment, posing a serious threat to human health.

Download Full-text