Assessment of acid sulfate soil mapping utilizing chemical indicators in recipient waters

Beucher, Amélie; Fröjdö, Sören; Österholm, Peter; Auri, Jaakko; Martinkauppi, Annu; Edén, Peter

doi:10.17741/bgsf/87.1.001

Cited by 7 publications

(2 citation statements)

References 19 publications

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“…Due to postglacial isostatic uplift extending the Littorina Sea shoreline up to 100 m above sea level (a.s.l. ), this area today covers c. 50 100 km 2 of the coast of Finland (Beucher et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Subsurface hydrochemical precision treatment of a coastal acid sulfate soil

Dalhem

Engblom

Stén

et al. 2019

Applied Geochemistry

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Some of the most economically valued soils for agricultural use are naturally occurring sulfide rich sediments. However, formation of acid sulfate soils with sulfuric materials (pH 4) can occur when sulfidic materials are exposed to air, which can then result in mobilisation of large amounts of acid and metals into nearby water bodies. In this study, controlled drainage, subsurface irrigation and hydrochemical precision treatments are combined to reduce acidic discharges on a novel project field in western Finland. The PRECIKEM project field consists of nine identical hydrologically isolated 1 ha subfields. Each field had a drainage system consisting of three subsurface drainage pipes (c. 1.3 m deep), a collector pipe, and a control well enabling manual groundwater table management. Utilising such drainage installations already common on farmlands, suspensions of fine-grained (d 50 = 2.5 µm) calcium carbonate and/or calcium hydroxide were pumped in to control wells in order to be distributed in to subsoils with sulfuric materials via drainage networks with the aim to: (1) neutralise acidity, (2) inhibit microbially mediated sulfide oxidation and (3) immobilise metals. The discharge waters from the fields were monitored during the project period 2012-2016. As is typical for acid sulfate soils with sulfuric materials, the discharge waters from the reference fields (n = 3) that had been treated with water only, had very low pH values ( 4) and the acidity and concentrations of several metals were up to two magnitudes higher than the average in Finnish stream waters. Excavation of selected treated fields revealed the calcium carbonate to have formed a neutralising coating on the surfaces of hydrologically active macropores in the soil matrix near the subsurface drainage pipes. This effectively resulted in a long-term (1-4 years) situation of raised pH, lower acidity and lower concentrations of several acid sensitive metals, most prominently a significant decrease (> 90%) in Al concentrations. Fe concentrations in discharge waters were subsequently decreased as the predominance of Fe shifted toward the schwertmannite and iron oxides stability phases due to changes in pH/redox conditions. The methods presented in this work showed favourable steps toward environmentally sustainable agriculture and improving the chemical and ecological status of acid sulfate soil affected coastal waters.

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Section: Introductionmentioning

confidence: 99%

Subsurface hydrochemical precision treatment of a coastal acid sulfate soil

Dalhem

Engblom

Stén

et al. 2019

Applied Geochemistry

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“…Sulfuric soil acidity has severe negative impacts on the general use and management of the environment in which ASS are present (Fitzpatrick et al, 2008;Michael, 2013). Of the estimated 17-24 million ha of ASS (Simpson and Pedini, 1985;Ljung et al, 2009), 6.5 million occur in Asia, 4.5 million in Africa, 3 million in Australia, 3 million in Latin America, 260 000 in Finland, 225 000 in Sweden and 100 000 in North America (Andriesse et al, 2006;Beucher et al, 2015), respectively.…”

Section: Introductionmentioning

confidence: 99%

Impact of common reed and complex organic matter on the chemistry of acid sulfate soils

Michael

Reid

2018

J. Soil Sci. Plant Nutr.

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Acid sulfate soils (ASS) are naturally occurring soils or sediments formed under reducing conditions that either contain sulfuric acid or have the potentail to form it, in an amount that can have adverse imapcts on the environment. The negative impacts of ASS are associated with the release of acidity produced and the release of toxic metals and metaloids from solubulised soil matricies into the environment. It has been shown recently that addition to ASS of dead plant material as organic matter creates microenvironments for soil microbes to ameliorate sulfuric soil and prevent sulfidic soil oxidation. Initial breakdown of the organic matter results in an oxygen demand that generates anaerobic conditions conducive to the reduction of sulfate to sulfides by sulfate reducing bacteria using the residual organic material as a carbon source and causing the pH to rise. There is also evidence that live plants increase acidification, potentially by aerating the soil. In nature, plants shed dead material as they grow, so that both live and dead organic matter co-exist. It is not known what happens to ASS chemistry, particularly pH, under such natural conditions. In this study, Phragmites australis was used to examine the combined effect of growing plants and incorporated organic matter on ASS chemistry (pH, redox potential and sulfate content) under aerobic and anaerobic conditions. In almost all cases, live plants enhanced sulfuric soil acidity and sulfidic soil oxidation. The mechanism for these changes on ASS chemistry appears to be the facilitation of oxygen penetration into the soil via aerenchymatous tissues in the plant roots.

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