UNSATURATED TRANSPORT PROCESSES IN UNDISTURBED HETEROGENEOUS POROUS-MEDIA .2. COCONTAMINANTS

被引:67
作者
JARDINE, PM [1 ]
JACOBS, GK [1 ]
ODELL, JD [1 ]
机构
[1] UNIV TENNESSEE,DEPT PLANT & SOIL SCI,KNOXVILLE,TN 37901
关键词
D O I
10.2136/sssaj1993.03615995005700040013x
中图分类号
S15 [土壤学];
学科分类号
0903 ; 090301 ;
摘要
Department of Energy facilities involved in defense-related activities have generated huge quantities of low-level radioactive mixed waste during the past several decades. The waste is composed of organically complexed contaminants, also known as co-contaminants, which are typically disposed in shallow land burial sites. The objective of this study was to provide an improved understanding of the geochemical processes controlling co-contaminant transport in heterogeneous, unsaturated subsurface media. Large undisturbed columns were isolated from a proposed waste site consisting of fractured saprolitic shale, and the steady-state unsaturated transport of Co(II)EDTA2-, Co(III)EDTA-, and SrEDTA2- was investigated at -10 cm pressure head. Subsurface Fe and Al sources effectively dissociated the Sr-EDTA2- co-contaminant and Sr was transported as a reactive, uncomplexed species. The EDTA readily complexed with Fe and Al, resulting in significant solid-phase modification of the porous media via chelate-enhanced dissolution and redox alterations. Displacement of Co(II)EDTA2- through the subsurface media was characterized by a MnO2-mediated oxidation of the co-contaminant with subsequent formation of Co(III)EDTA-. The latter co-contaminant was an extremely stable complex that was transported through the subsurface as a single, reactive entity and exhibited an overall retardation that was similar to the uncomplexed contaminant Co2+. Modeling results using equilibrium and nonequilibrium formulations of the convective-dispersive equation suggested that a large portion of the transported Co(III)EDTA- was controlled by time-dependent sorption reactions with the solid phase. Although the solid-phase retention of Co(III)EDTA- and Co2+ were similar, the sorption kinetics of the former were more sluggish relative to Co2+ and contaminant transport was accelerated in the presence of EDTA.
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页码:954 / 962
页数:9
相关论文
共 30 条
[1]   SEQUENTIAL EXTRACTION OF IRON, MANGANESE, ALUMINUM, AND SILICON IN SOILS FROM 2 CONTRASTING WATERSHEDS [J].
ARNSETH, RW ;
TURNER, RS .
SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 1988, 52 (06) :1801-1807
[2]  
AYRES JA, 1971, BNWLB90 SURV REP BAT
[3]  
Bartlett R. J., 1986, Soil physical chemistry, P179
[4]   SPECTROPHOTOMETRIC DETERMINATION OF EDTA [J].
BHATTACH.SN ;
KUNDU, KP .
TALANTA, 1971, 18 (04) :446-&
[5]   INTERACTIONS OF METAL HYDROUS OXIDES WITH CHELATING-AGENTS .4. DISSOLUTION OF HEMATITE [J].
CHANG, HC ;
MATIJEVIC, E .
JOURNAL OF COLLOID AND INTERFACE SCIENCE, 1983, 92 (02) :479-488
[6]   INTERACTIONS OF METAL HYDROUS OXIDES WITH CHELATING-AGENTS .3. ADSORPTION ON SPHERICAL COLLOIDAL HEMATITE PARTICLES [J].
CHANG, HC ;
HEALY, TW ;
MATIJEVIC, E .
JOURNAL OF COLLOID AND INTERFACE SCIENCE, 1983, 92 (02) :469-478
[7]   SOIL ADSORPTION OF CADMIUM FROM SOLUTIONS CONTAINING ORGANIC-LIGANDS [J].
ELLIOTT, HA ;
DENNENY, CM .
JOURNAL OF ENVIRONMENTAL QUALITY, 1982, 11 (04) :658-663
[8]  
FLASCHKA HA, 1976, CHELATES ANAL CHEM, V5
[9]  
GIRVIN DC, 1991, AGRONOMY ABSTRACTS, P243
[10]  
Hering J. G., 1990, AQUATIC CHEM KINETIC, P145