Factors Influencing Desorption of Mercury from Bed Sediments

1975 ◽  
Vol 12 (6) ◽  
pp. 1036-1040 ◽  
Author(s):  
Akira Kudo ◽  
D. C. Mortimer ◽  
J. Sanford Hart
Keyword(s):  
Environmental Conditions ◽  
Total Mercury ◽  
Exposure Period ◽  
Desorption Rate ◽  
Overlying Water ◽  
Bed Sediments ◽  
Ottawa River ◽  
Factors Influencing ◽  
River Bed

The desorption rate of mercury from bed sediments was determined by a 10 week experiment. The rates ranged from 0.1 ng/cm2/day to 1.0 ng/cm2/day for Ottawa River bed sediments, depending on the environmental conditions. The rates decreased with an increase of exposure period to the water, but increased with an increase in the depth of bed sediments. The amount of mercury desorbed from bed sediments to overlying water was highly dependent on the volume (depth) of bed sediments. Calculations based on the experiment showed the half-lives of total mercury associated with bed sediments from as short as 2.1 years to as long as 1.8 × 102 years, depending on the depth of the bed sediments.

scholarly journals Ether Oxidation by an Evolved Fungal Heme-Peroxygenase: Insights into Substrate Recognition and Reactivity

2021 ◽  
Vol 7 (8) ◽  
pp. 608
Author(s):  
Raul Mireles ◽  
Joaquin Ramirez-Ramirez ◽  
Miguel Alcalde ◽  
Marcela Ayala
Keyword(s):  
Molecular Weight ◽  
Environmental Conditions ◽  
Substrate Recognition ◽  
Enzyme Inactivation ◽  
Biochemical Reaction ◽  
Low Molecular Weight ◽  
Factors Influencing ◽  
Secondary Reactions ◽  
Oxidation Efficiency ◽  
Favorable Conditions

Ethers can be found in the environment as structural, active or even pollutant molecules, although their degradation is not efficient under environmental conditions. Fungal unspecific heme-peroxygenases (UPO were reported to degrade low-molecular-weight ethers through an H2O2-dependent oxidative cleavage mechanism. Here, we report the oxidation of a series of structurally related aromatic ethers, catalyzed by a laboratory-evolved UPO (PaDa-I) aimed at elucidating the factors influencing this unusual biochemical reaction. Although some of the studied ethers were substrates of the enzyme, they were not efficiently transformed and, as a consequence, secondary reactions (such as the dismutation of H2O2 through catalase-like activity and suicide enzyme inactivation) became significant, affecting the oxidation efficiency. The set of reactions that compete during UPO-catalyzed ether oxidation were identified and quantified, in order to find favorable conditions that promote ether oxidation over the secondary reactions.

The effect of the reunification of Germany on the water chemistry and ecology of selected rivers

1996 ◽  
Vol 23 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Michael S. Adams ◽  
Hartmut Kausch ◽  
Thomas Gaumert ◽  
Karl-Ernst Krüger
Keyword(s):  
Czech Republic ◽  
Species Diversity ◽  
Water Chemistry ◽  
Total Nitrogen ◽  
Chlorinated Hydrocarbons ◽  
The Czech Republic ◽  
Bed Sediments ◽  
Potash Mining ◽  
River Bed ◽  
Substantial Decline

SummaryWe review several studies and provide new data previously unpublished to show that there has been a substantial decline in pollution of German riverine waters since the beginning of German political reunification in 1989. This reduction is notable in the Elbe, which originates in eastern Germany and the Czech Republic. Pollutants such as many of the chlorinated hydrocarbons have fallen substantially in concentration, while others such as arsenic have declined only slightly. Total nitrogen has declined by only a small amount, but ammonium has fallen substantially, while nitrates have increased. Nitrification is no longer a significant drain on oxygen in the tidal stretch of the Elbe, but decomposition of algae from the middle Elbe is now a greater problem in the lower Elbe. The river-bed sediments of the middle Elbe have a higher species diversity. Fisheries are improving, and concentrations of pollutants in fish such as eel and bream have declined significantly. The river Werra has also improved in quality due to reduction in salt loadings from earlier potash mining.

Unreasonably Dangerous

1987 ◽  
Vol 31 (5) ◽  
pp. 600-604
Author(s):  
Michael W. Riley ◽  
David J. Cochran ◽  
Ram R. Bishu
Keyword(s):  
Human Factors ◽  
Human Behavior ◽  
Environmental Conditions ◽  
Good Manufacturing Practice ◽  
Human Errors ◽  
Factors Influencing ◽  
Human Capability

Human factors specialists need to assess products and situations to determine a level of dangerousness. This paper outlines the factors of such an analysis and suggests a procedure to use. Aspects of human behavior, environmental conditions, potential for encountering sources of energy and good manufacturing practice are addressed. The key elements of human capability and expectation are outlined. Products and activities that have inherent danger are discussed. Human errors and the factors influencing dangerous situations are discussed.

Provenance and weathering control on river bed sediments of the eastern Tibetan Plateau and the Russian Far East

2008 ◽  
Vol 254 (1-2) ◽  
pp. 52-72 ◽  
Author(s):  
Joniell B. Borges ◽  
Youngsook Huh ◽  
Seulgi Moon ◽  
Hyeonjeong Noh
Keyword(s):  
Tibetan Plateau ◽  
Russian Far East ◽  
Far East ◽  
Eastern Tibetan Plateau ◽  
Bed Sediments ◽  
River Bed ◽  
The Russian Far East

Diffusive movement of simazine and lindane in river-bed sediments

1998 ◽  
Vol 54 (3) ◽  
pp. 212-222 ◽  
Author(s):  
W. M. Daniels ◽  
W. A. House ◽  
B. V. Zhmud ◽  
J. E. Rae ◽  
A. Parker
Keyword(s):  
Bed Sediments ◽  
River Bed ◽  
Diffusive Movement

Optimized Environmental Conditions for Petroleum Degradation of Strain B1 by Orthogonal Test

2011 ◽  
Vol 393-395 ◽  
pp. 1308-1312
Author(s):  
Chun Xu Wu ◽  
Hong Tao Zhang ◽  
Bei Hai Zhou ◽  
Lei Gao ◽  
Hao Deng ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Wastewater Treatment ◽  
Environmental Impact ◽  
Environmental Conditions ◽  
Treatment Plant ◽  
Orthogonal Test ◽  
Oil Field ◽  
Impact Factors ◽  
Factors Influencing ◽  
Biodegradation Efficiency

A strain B1 belonging to Pseudomonas aeruginosa with high petroleum-degrading efficiency was isolated from Dagang oil-field wastewater treatment plant. More than 80% petroleum-degrading efficiency was obtained at 32°C, 200 r/min. According to the orthogonal test, the environmental impact factors influencing petroleum-degrading efficiency of the strain were investigated. The optimum environmental conditions for petroleum degradation were as follows: temperature was 40 °C, pH 8.0, oil inoculation 1 mL, nitrogen content 0.05 g. And the biodegradation efficiency of the strain reached 86.1%.

scholarly journals Sources of organic matter in Changjiang (Yangtze River) bed sediments: Preliminary insights from organic geochemical proxies

2015 ◽  
Vol 85 ◽  
pp. 11-21 ◽  
Author(s):  
Zhongqiao Li ◽  
Francien Peterse ◽  
Ying Wu ◽  
Hongyan Bao ◽  
Timothy I. Eglinton ◽  
...  
Keyword(s):  
Organic Matter ◽  
Yangtze River ◽  
Bed Sediments ◽  
Geochemical Proxies ◽  
River Bed

Factors Affecting Locking Times at 600' and 1200' Locks on the Mississppi River with an Examination of Excessive Locking Time Charges

2010 ◽  
Author(s):  
Seth D. Meyer ◽  
John Kruse
Keyword(s):  
Mississippi River ◽  
Environmental Conditions ◽  
Time Variation ◽  
Army Corps ◽  
Upper Mississippi River ◽  
Army Corps Of Engineers ◽  
Corps Of Engineers ◽  
Factors Affecting ◽  
Identification Number ◽  
Factors Influencing

This research investigates factors influencing locking time as well as the source of variation in the locking time on the Upper Mississippi River, and includes tow characteristics and environmental conditions over 1992-2004. The newer 1,200 ft. locks reduce both locking time and time variation, improving efficiency on the system as a whole. Importantly, the analysis suggests lock capacity has declined over the 1992 to 2004 period for all locks. After correcting for tow and environmental characteristics, very little of the remaining variation is explained by a unique vessel identification number assigned by the Army Corps of Engineers, indicating that lockage fees based purely on relative locking times would not provide the intended result.

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