Allochthonous versus autochthonous naturally occurring organic matter in the Anllóns river bed sediments (Spain)

SummaryWe review several studies and provide new data previously unpublished to show that there has been a substantial decline in pollution of German riverine waters since the beginning of German political reunification in 1989.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.

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Factors Influencing Desorption of Mercury from Bed Sediments

Canadian Journal of Earth Sciences ◽

10.1139/e75-094 ◽

1975 ◽

Vol 12 (6) ◽

pp. 1036-1040 ◽

Cited By ~ 17

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.

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

Chemical Geology ◽

10.1016/j.chemgeo.2008.06.002 ◽

2008 ◽

Vol 254 (1-2) ◽

pp. 52-72 ◽

Cited By ~ 62

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

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Point-of-entry adsorbers for the removal of fumigants

Canadian Journal of Civil Engineering ◽

10.1139/l95-010 ◽

1995 ◽

Vol 22 (1) ◽

pp. 106-120

Author(s):

Roberto M. Narbaitz ◽

Frances Z. Parsons ◽

Tsong-Yih Tzeng

Keyword(s):

Organic Matter ◽

Activated Carbon ◽

Low Cost ◽

Scale Up ◽

Extensive Literature ◽

Limited Data ◽

Ethylene Dibromide ◽

Point Of Entry ◽

Naturally Occurring ◽

Adsorption Data

Point-of-entry systems with granular activated carbon filters have been used extensively to provide safe water to rural homes with wells contaminated with synthetic organic chemicals. Because of the low cost of these systems, their design is generally based on the equilibrium column model, the isotherm data from the literature, and a scale-up factor. This paper analyzes the necessary scale-up factors for point-of-entry adsorbers based on fumigant adsorption data gathered through an extensive literature review. The fumigants evaluated are 1,2-dichloropropane, 1,2-dibromo-3-chloropropane, and ethylene dibromide. It was impossible to thoroughly assess the scale-up factors for 1,2-dichloropropane because of the limited data. Column data for the other two fumigants were sufficient to generate column loading lines, which can be used directly without resorting to scale-up factors. Column data showed that the scale-up factors are greatly affected by competitive adsorption with the naturally occurring background organic matter and by preloading of these organic matter. As these phenomena are not well understood, it is presently impossible to accurately predict the appropriate scale-up factors. A recommended design approach is outlined. Key words: adsorption, activated carbon, fumigants, point-of-entry.

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