Infiltration Studies With Sodic Mine Spoil Material

Jin²

2006

Weathering characteristics of minesoils and rooting patterns of key shrub and grass species were evaluated at sites reclaimed for 6 to 14 years from three surface coal mine operations in northwestern New Mexico and northeastern Arizona. Non-weathered minesoils were grouped into 11 classifications based on electrical conductivity (EC) and sodium adsorption ratio (SAR). Comparisons of saturated paste extracts, from non-weathered and weathered minesoils show significant (p < 0.05) reductions in SAR levels and increased EC. Weathering increased the apparent stability of saline and sodic minesoils thereby reducing concerns of aggregate slaking and clay particle dispersion. Root density of fourwing saltbush (Atriplex canascens), alkali sacaton (Sporobolus airoides), and Russian wildrye (Psathyrostachys junceus) were nominally affected by increasing EC and SAR levels in minesoil.

Section: Introductionmentioning

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Salinity and Sodicity Interactions of Weathered Minesoils in Northwestern New Mexico and North Eastern Arizona

Jin²

2006

“…In two different field studies at the West Decker mine in Montana, SAR levels decreased 8.0 to 9.0 mmol 1/2 L -1/2 in the upper 30 cm of minesoil over a 2 to 7 yr period due to apparent increases in Ca +2 and Mg +2 and leaching of Na + (Dollhopf et al, 1980;Richardson and Farmer, 1982). Similarly, Weber et al (1979) found that SAR in northwestern New Mexico minesoils was reduced from 37.7 to 3.70 and 8.00 mmol 1/2 L -1/2 at the 0 to 6.4 cm and 6.4 to 12.7 cm depths, respectively, following eight irrigations (32 cm) of low salinity (EC = 1.00 dS m -1 ) tap water. Carlstrom et al (1987) reported that occasional heavy rain or winter snowmelt promoted downward salt leaching and decreased EC and SAR with time in reclaimed minesoils with coversoils at the San Juan Mine in New Mexico.…”

Section: Introductionmentioning

confidence: 78%

“…This reduction was largely due to increased soluble Ca 2+ that was attributed to the dissolution of CaCO 3 , delamination of Ca-tactoids, and, for two samples, dissolution of CaSO 4 •2H 2 O. Weber et al, (1979) conducted a column study to evaluate the effects of irrigation water quality, amendment type, and timing of amendment application on infiltration rates of saline-sodic minesoils from the San Juan Basin, New Mexico. The SAR values at the 0 to 6.4 and 6.4 to 12.7 cm minesoil depths were reduced from 38 mmol 1/2 L -1/2 to 3.7 and 8.0 mmol 1/2 L -1/2 , respectively, after irrigation with low salinity tap water.…”

Section: Minesoil Weatheringmentioning

confidence: 99%

Salinity and Sodicity Interactions of Weathered Minesoils in the Four Corners Region

Vinson²,

Johnston³

et al. 2006

JASMR

Abstract. Relationships between electrical conductivity (EC) and sodium adsorption ratio (SAR) changes over time in reconstructed soils at surface coal mining operations are insufficiently documented in the literature. Some minesoils (i.e., rootzone material) are classified as saline, sodic, or saline-sodic and have been considered unsuitable rooting media for establishment of native vegetation. Weatherable minerals (e.g., pyrite, calcite, gypsum, and other geologic substrates) commonly present in minesoils can mitigate the effects of elevated SAR levels by maintaining or increasing electrolytes in the soil and provide sources of exchangeable calcium and magnesium. Coversoil (i.e., topsoil) enhances this mitigation through physical and chemical buffering of minesoils. Weathering characteristics of minesoils and rooting patterns of key reclamation species were evaluated at sites from three surface coal mines in northwestern New Mexico and northeastern Arizona.Unweathered minesoils were grouped into 11 classifications based on EC and SAR. Comparison of saturated paste extracts from unweathered and weathered (6 to 14 years after reclamation) minesoils show significant (p < 0.05) reductions in SAR levels and increased EC. Weathering increased the apparent stability of saline and sodic minesoils thereby reducing risks of aggregate slaking and clay particle dispersion. Root density of fourwing saltbush (Atriplex canescens), alkali sacaton (Sporobolus airoides), and Russian wildrye (Psathyrostachys junceus) were generally unaffected by increasing minesoil EC and SAR levels. Saline and sodic minesoils can be successfully reclaimed when covered with topsoil and seeded with salt tolerant plant species.

“…This reduction was largely due to increased soluble Ca 2+ that was attributed to the dissolution of CaCO 3 , delamination of Ca‐tactoids, and, for two samples, dissolution of CaSO 4 ·2H 2 O. Weber et al (1979) conducted a column study to evaluate the effects of irrigation water quality, amendment type, and timing of amendment application on infiltration rates of saline‐sodic minesoils from the San Juan Basin, New Mexico. The SAR values of 0 to 6.4 and 6.4 to 12.7 cm minesoil depths were reduced from 38 mmol 1/2 L −1/2 to 3.7 and 8.0 mmol 1/2 L −1/2 , respectively, after irrigation with low salinity waters.…”

Section: Resultsmentioning

confidence: 99%

Salinity and Sodicity of Weathered Minesoils in Northwestern New Mexico and Northeastern Arizona

Vinson

Johnston

et al. 2009

J of Env Quality

Evolving relationships between electrical conductivity (EC) and sodium adsorption ratio (SAR) in reconstructed soils at surface mines have been insufficiently documented in the literature. Some minesoils (i.e., rootzone material) are classified as saline, sodic, or saline-sodic and are considered unsuitable for revegetation. Weatherable minerals such as calcite and gypsum are common in alkaline minesoils and on dissolution tend to mitigate elevated SAR levels by maintaining or increasing electrolytes in the soil and providing sources of exchangeable calcium and magnesium. Topsoils (i.e., coversoils) contribute to mitigation of sodic conditions when soluble cations are translocated from coversoils into the underlying minesoils. This study evaluated the weathering characteristics of minesoils sites from three surface coal mines in northwestern New Mexico and northeastern Arizona. Minesoils were grouped into 11 classes based on EC and SAR. After 6 to 14 yr, differences between upper and lower halves of the coversoils suggest general increases occurred with EC, SAR, chloride (Cl(-)), and sulfate (SO(4)(2-)) with depth. Within the reclaimed minesoils, there were several significant (P < 0.05 or < 0.10) relationships among EC and SAR that related to Minesoil Class. Lower SAR levels with corresponding increases in EC compared to baseline minesoils were more apparent in upper minesoil depths (0-5 and 5-15 cm). Minesoil anion concentrations suggested coversoil leachates and gypsum dissolution influenced EC and SAR chemistry. Over time, chemical changes have increased the apparent stability of the saline and sodic reclaimed minesoils studied thereby reducing risks associated with potential aggregate slaking and clay particle dispersion.