Role of mineralogy in areas affected by natural acid saline seeps, southwestern Australia

Abstract

The study of morphological and mineralogical changes within a natural acid saline seep affected landscape revealed that seasonal differences in surface mineralogy, reflecting the operation of sulfidization and oxidative sulfide weathering processes. During the wet season, the surface and near surface of the waterlogged seep and marsh areas is dominated by black sulfidic materials (pyrite) and minor salt crusts, with negligible iron oxides and oxyhydroxides. The Fe and S emerging from seeps contribute to the sulfidization processes operative in reducing conditions within the waterlogged zones. During the dry season, the surface mineralogy of the natural seepage zone is dominated by salts (halite), sulfates (gypsum and barite) and importantly, iron oxyhydroxides gel precipitates and crusts (ferrihydrite, goethite, schwertmannite). The gradual drying of previously waterlogged zones during summer facilitates oxidative weathering of the sulfides, which together with rapid oxidation of Fe2+ emerging from the still persisting minor seeps, results in the formation of iron oxyhydroxides and acid generation. The visible near infra-red (VNIR) reflectance spectra of the surface minerals from unaffected, salt crusted and acid seep areas, showed spectral differences expressed in the VNIR region due to absorption bands of iron oxides and hydroxides. The spectral difference can be utilized for regional scale mapping of acid seeps and acid sulfate soils of affected areas via hyperspectral and multispectral remote sensing.

Keywords


[1] Schrock M., Mankin K., Lamond R., "Controlling saline seeps", Kansas Stata University, Agricultural Experiment Station and Cooperative Extension Service, MF-2391, Soil Management ( 1999 ) 4 pp.

[2] Fitzpatrick R. W., "Inland acid sulfate soils: A big growth area", In 5th International Acid Sulfate Soils Conference, Tweed Heads, NSW (Book of Extended Abstracts) (2002).

[3] Berner R. A., "Sedimentary pyrite formation, Am", J. Sci. 268 (1970)1-23.

[4] Fanning D. S., Fanning M. C. B., "Soil morphology, genesis, and classification", Wiley, New York. (1989).

[5] Schwertmann U., Fitzpatrick R. W., "Iron minerals in surface environments", ed. by: Skinner H. C. W., Fitzpatrick R. W., "Biomineraliz-ation processes of Iron and Manganese – Modern and ancient environments", Catena Suppl. 21 (1992) 7-30.

[6] Van Breemen N., "Effects of seasonal redox processes involving iron on the chemistry of periodically reduced soils", ed. by: Stucki J. W., Goodman B. A., Schwertmann U., "Iron in soils and clay minerals", Reidel, Dordrecht (1988) 797-842.

[7] Brinkman R., Pons L. J., "Recognition and predication of acid sulfatesoil condition", ed. by: Dost H., "Acid sulfate soils", ILRI Publ. 18, Wageningen (1973) 169-203.

[8] Naidu R., Fitzpatrick R. W., Hudnell W. H., "Chemistry of saline sulphidic soils with altered water regime in the Mount Lofty Ranges, South Australia", ed. by: Monchareon L., et al., Proc. Int. Symp. "On Strategies for Utilizing Salt Affected Lands", Bangkok, Thailand (1992) 477-480.

[9] Fitzpatrick R. W., Fritsch E., Self P. G., "Interpretation of soil features produced by ancient and modern processes in degraded landscapes: V Development of saline sulfidic features in non-tidal seepage areas", Geoderma 69 (1996) 1-29.

[10] George R. J., McFarlane D. J., Nulsen R. A., "Salinity threathens the viability of agriculture and ecosystems in Western Australia", Hydrogeology Journal 5(1997) 6-21.

[11] George R. J., "Secondary acidification an emerging problem in wheatbelt", Focus on Salt 23(2002) 10.

[12] Edkins R., "Westdale focus group catchment report, Salinity Action Plan", Australian gov. Report (1998).

[13] Lewis M. F., McConnel C. E., "Observations on groundwater recharge in the Westdale catchment. Agriculture, Western Australia", Resource Management Technical Report 180 (1998).

[14] Bigham J. M., Fitzpatrick R. W., Schulze D.,"Iron Oxides", ed. by: Dixon J. B., Schulze D. G., "Soil Mineralogy with Environmental Applications", Soil Science Society of America Special Publications. Madison, Wisconsin, USA (2001) 323-366.

[15] Cudahy T., Ramanidou E., "Measurement of the hematite :goethite ratio using field visible and near-infrared reflectance spectrometry in channel iron deposits, WA. Australian", Journal of Earth Sciences (1997) 411-420.

[16] Crowley J. K., Williams D. E., Hammarstrom, J. M., I-Ming C., Mars J. C., "Spectral reflectance properties (0.4-2.5 m) of secondary Fe-oxide, Fe-hydroxide, and Fe-sulphate –hydrate minerals associated with sulphide-bearing mine wastes", Geochemistry: Exploration, Environments and Analysis 3 (2003) 219-228.

[17] Swayze G. A., Smith K. M., Clark R. N., Sutley S. J., Pearson R. M., Vance J. S., Hageman P. L., Briggs P. H., Meier A. L., Singleton M. J., Roth S., "Using imaging spectroscopy to map acidic mine waste", Environmental Science and Technology 34 (2000) 47-54.

[18] Manceau A., Marcus M. A., Tamura, N., "Quantitative speciation of heavy metals in soils and sediments by Synchrotron X-ray Techniques", ed. by: Fenter P. A, Rivers M. L., Sturchio N. C., Sutton S. R, "Applications of synchrotron radiation in low-temperature", geochemistry and environmental science (eds) (2002) 341-428.