Bioturbation and Other Sorbed-Phase Transport Processes in Surface Soils and Sediments

2010 ◽  
pp. 359-388
Author(s):  
Louis Thibodeaux ◽  
Gerald Matisoff ◽  
Danny Reible
Keyword(s):  
Transport Processes ◽  
Surface Soils ◽  
Soils And Sediments ◽  
Phase Transport ◽  
Sorbed Phase

The Influence of Vertical Sorbed Phase Transport on the Fate of Organic Chemicals in Surface Soils

2002 ◽  
Vol 36 (22) ◽  
pp. 4860-4867 ◽  
Author(s):  
Michael S. McLachlan ◽  
Gertje Czub ◽  
Frank Wania
Keyword(s):  
Organic Chemicals ◽  
Surface Soils ◽  
Phase Transport ◽  
Sorbed Phase

scholarly journals Evolution of the Speciation and Mobility of Pb, Zn and Cd in Relation to Transport Processes in a Mining Environment

2020 ◽  
Vol 17 (14) ◽  
pp. 4912 ◽  
Author(s):  
Intissar Elmayel ◽  
José María Esbrí ◽  
García-Ordiales Efrén ◽  
Eva-María García-Noguero ◽  
Zouhair Elouear ◽  
...  
Keyword(s):  
Ammonium Acetate ◽  
Source Area ◽  
Selective Extraction ◽  
Transport Processes ◽  
Mineral Phases ◽  
Standard Procedures ◽  
Evolution Pattern ◽  
Mobile Forms ◽  
Combined Use ◽  
Soils And Sediments

Elements in mining extracts can be potentially toxic if they are incorporated into soils, sediments or biota. Numerous approaches have been used to assess this problem, and these include sequential extractions and selective extractions. These two methods have limitations and advantages, and their combined use usually provides a rough estimate of the availability or (bio)availability of potentially toxic elements and, therefore, of their real potential as toxicants in food chains. These indirect speciation data are interesting in absolute terms, but in the work described here, this aspect was developed further by assessing the evolution of availability-related speciation in relation to the transport processes from the emission source, which are mainly fluvial- and wind-driven. This objective was achieved by characterizing tailings samples as the source of elements in soils and sediments at increasing distances to investigate the evolution of certain elements. The standard procedures employed included a sequential five-step extraction and a selective extraction with ammonium acetate. The results show that the highest percentages of Zn and Pb in tailings, soils and sediment samples are associated with oxyhydroxides, along with a significant presence of resistant mineralogical forms. In the case of Cd, its association with organic matter is the second-most important trapping mechanism in the area. The physicochemical mechanisms of transport did not transform the main mineralogical associations (oxyhydroxides and resistant mineralogical forms) along the transects, but they produced a chaotic evolution pattern for the other minor matrix associations for Zn and a decrease in exchangeable and carbonate-bound forms for Pb in soils. Interestingly, in sediments, these mobile forms showed a decrease in Zn and a chaotic evolution for Pb. The most probable reason for these observations is that Zn2+ can form smithsonite (ZnCO3) or hydrozincite (Zn5(CO3)2(OH)6), which explains the retention of a carbonate-bound form for Zn in the soil transect. In contrast, Pb and Cd can appear as different mineral phases. The order of (bio)availability was Pb > Zn > Cd in tailings but Cd > Pb > Zn in soils. The physicochemical processes involved in transport from tailings to soils produce an increase in Cd (bio)availability. The trend is a decrease in bioavailability on moving away from the source (tailings), with maximum values obtained for Cd near to the source area (200–400 m).

scholarly journals Laboratory study of retention and release of weak acid herbicide MCPA by soils and sediments and leaching potential of MCPA

2011 ◽  
Vol 52 (No. 12) ◽  
pp. 550-558 ◽  
Author(s):  
E. Hiller ◽  
M. Khun ◽  
L. Zemanová ◽  
Ľ. Jurkovič ◽  
M. Bartaľ
Keyword(s):  
Aqueous Solution ◽  
Organic Carbon ◽  
Carbon Content ◽  
River Sediments ◽  
Weak Acid ◽  
Organic Carbon Content ◽  
Surface Soils ◽  
Leaching Potential ◽  
Soil Sediment ◽  
Soils And Sediments

MCPA sorption and desorption in five surface soils (denoted as A1-5), three bottom sediments (S1-3), two river sediments (L1-2) and one subsurface soil (SS) at two initial concentrations in aqueous solution &ndash; C<sub>0</sub> = 0.5 and 10&nbsp;mg/l were studied. No significant effect of the initial concentration on MCPA equilibrium distribution between soil/sediment and aqueous solution was observed. The difference between distribution coefficient K<sub>D</sub> at C<sub>0</sub> = 0.5&nbsp;mg/l and K<sub>D</sub> at C<sub>0</sub> = 10 mg/l was found only in the case of one bottom sediment (S2). A simple regression analysis between K<sub>D</sub> at C<sub>0</sub> = 0.5 and 10 mg/l and soil/sediment properties indicated that the most important property which determined the variation in MCPA sorption is organic carbon (r = 0.886*** and r = 0.926***, respectively). Similarly, desorption of MCPA was inversely proportional to organic carbon content of the soils and sediments used (r = &ndash;0.862* and r = &ndash;0.842**). These observations showed that MCPA sorption and desorption in soils and sediments were primarily controlled by organic components of the geosorbents used. Overall, the percentage of MCPA sorption in soils and sediments was low (P<sub>sorp</sub> &asymp; 3&ndash;53%; K<sub>D</sub> = 0.077&ndash;2.827 l/kg) and the percentage of MCPA desorbed was relatively high (P<sub>des</sub> &asymp; 11&ndash;70%), especially in the soils and sediments with lower organic carbon content. The experimental results and calculated values of groundwater ubiquity score GUS and relative leaching potential index RLPI imply that MCPA is very mobile in all the surface soils and has a potential to contaminate groundwater.

Single-phase transport processes in the closed thermosyphon

1971 ◽  
Vol 14 (7) ◽  
pp. 869-887 ◽  
Author(s):  
D Japikse ◽  
P.A Jallouk ◽  
E.R.F Winter
Keyword(s):  
Single Phase ◽  
Transport Processes ◽  
Phase Transport
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