P. Sutton’s research while affiliated with The Ohio State University and other places

Removal of SOâ from the emissions of coal-fired boilers produces by-products that often consist of CaSOâ, residual alkalinity, and coal ash. These by-products could be beneficial to acidic soils because of their alkalinity and the ability of gypsum (CaSOâ{center{underscore}dot}2HâO) to reduce Al toxicity in acidic subsoils. A 3-yr field experiment was conducted to determine the liming efficacy of a fluidized bed combustion boiler by-product (FBC) that contained 129 g Mg kg⁻¹ as CaMg(COâ)â and MgO and its effects on surface and subsurface soil chemistry. The FBC was mixed in the surface 10 cm of two acidic soils (Wooster silt loam, an Oxyaquic Fragiudalf, and Coshocton silt loam, an Aquultic Hapludalf) at rates of 0, 0.5, 1, and 2 times each soil's lime requirement (LR). Soils were sampled in 10-cm increments to depths ranging from 20 to 110 cm, and corn (Zea mays L.) and alfalfa (Medicago sativa L.) were grown. Application of Mg-FBC increased alfalfa yields in all six site-years, whereas it had no effect on corn grain yield in five site-years and decreased grain yield in one site-year. Plant tissue concentrations of Mg, S, and Mo were increased by Mg-FBC, while most trace elements were either unaffected or decreased. Application of Mg-FBC at one or two times LR increased surface soil pH to near 7 within 1 wk. Although surface soil pH remained near 7 for 2 yr, there was minimal effect on subjacent soil pH. Application of Mg-FBC increased surface soil concentrations of Ca, Mg, and S, which promoted downward movement of Mg and SOâ. This had different effects on subsoil chemistry in the two soils: in the high-Ca-status Wooster subsoil, exchangeable Ca was decreased and exchangeable Al was increased, whereas in the high-Al-status Coshocton subsoil, exchangeable Al was decreased and exchangeable Mg was increased. The Mg-FBC was an effective liming material and, because of the presence of both Mg and SOâ, may be more effective than gypsum in ameliorating subsoil Al phytotoxicity.

Clean air legislation has resulted in increased production of flue gas desulfurization (FGD) by-products by coal-fired boilers. Use of FGD by-products as substitutes for agricultural limestone represents a potential beneficial use alternative to landfill disposal of these materials. To determine the efficacy and potential for environmental impact of such use, an 8-month greenhouse study was conducted in which three dry FGD by-products were mixed with Wooster silt loam at rates of 0, 3.5, 7, 14, and 28 g kg-1. Separate pots were planted with alfalfa (Medicago sativa, L) and tall fescue (Festuca arundinacea, Schreb). Following a 3-month growth period, plants were harvested monthly for a total of six harvests. Pots were leached at the beginning and end of the experiment. All three FGD by-products increased soil pH from 4.5 to approximately 7.5. Leachate concentrations of Ca, Mg, and S were increased by FGD, indicating a potential for transport of these solutes to subjacent soil. Leachate Mn and Zn concentrations were decreased by FGD amendment of alfalfa, and leachate Al was decreased with both crops. Leachate trace element concentrations were not increased by FGD with the exceptions of B and Cu. Alfalfa yield was increased by FGD, although the largest amendments suppressed yields of the first two harvests. Fescue yield was also increased by FGD amendment although the response was less than with alfalfa. Plant tissue contents of Ca, Mg, and S were increased by FGD. There were no increases in tissue concentrations of any trace elements except B and Mo. Dry FGD by-products appear to be effective substitutes for agricultural limestone with little potential for adverse environmental impacts.

Gypsum (G) and Mg (OH)â (FGD-Mg) are recovered from the thickener overflow of an experimental wet FGD scrubber in the Zimmer power plant of CINergy (Cincinnati Gas and Electric Company). The purity of recovered G ranges from almost 100 to 92%, with impurities occurring mainly as Mg(OH)â. Gypsum contaminated with Mg(OH), is referred to as Mg(OH)â-enriched by-product gypsum (Mg-G). Because of its Mg(OH)â content, Mg-G can potentially be used as a source of both Ca and Mg for green plants growing on soils and spoils with low levels of available Ca and Mg. In addition, the presence of Mg(OH)â should allow Mg-G to be used as an alkaline amendment for the reclamation of hyper-acid spoils. The total abandoned surface coal mined land needing reclamation in eastern USA has been estimated to be more than 0.5 million ha. Gypsum can reduce Al toxicity by: (1) increased ratio of Ca to Al in the soil solution, and (2) physical removal of Al from the soil profile through Ca exchange. The Mg(OH)â in Mg-G may enhance the effectiveness of these mechanisms for amelioration of phytotoxic conditions below the zone of incorporation. The presence of Mg and sulfate increases the potential for salt loading, which may enhance downward movement of Ca and Al. The purpose of this greenhouse study was to investigate the effects of G and Mg-G, at three application rates, on spoil and leachate pH and electrical conductivity (EC), and movement of major and trace elements. Preliminary observations on plant growth are also reported.

One potential use for alkaline, dry flue gas desulfurization (FGD) by- products is in reclamation of acidic minespoils. Greenhouse column studies of 8-mo duration investigated growth and tissue composition of plants grown on three acidic minespoils amended with two dry FGD by-products (lime injection multistage burners, LIMB; and, pressurized fluidized bed combustion, pFBC). Amendment amounts ranged from 0 to 320 g kg -1 by dry weight. Two minespoils also were amended with sewage sludge at 60 g kg -1 by dry weight. Column mixes were planted with Kentucky 31 tall fescue (Festuca arundinacea Schreb.). After 92 d of growth, fescue was harvested every 30 d for a total of six harvests. Tissue composition was determined on material from the sixth harvest. Root growth was measured at the end of the experiment. Fescue growth was improved by FGD amendments of 30 to 120 g kg -1, but larger amendments caused high pH and cementation, which decreased rescue growth and limited rooting volume. Plant tissue composition was generally within sufficiency ranges for the elements analyzed. Tissue Ca, Mg, and S were increased by FGD amendment, while tissue concentrations of most trace elements were decreed. There was no increase in tissue B from PFBC, however, LIMB application caused B concentrations >100 mg kg -1, which could be toxic to less tolerant species. These results indicate that when applied in amounts equivalent to spoil neutralization needs, dry FGD by-products can benefit acidic spoil revegetation with little potential for introduction of toxic elements into the food chain.

Greenhouse column studies of 8 mo duration investigated the solubility and mobility of salts and trace elements in dry flue gas desulfurization (FGD) by-products used for minespoil reclamation. Three mine-spoils were amended with two dry FGD by-products (lime injection multistage burners ash, LIMB; and, pressurized fluidized bed combustion ash, PFBC) using amounts from 0 to 320 g kg -1. Two of the minespoils also received sewage sludge amendment of 60 g kg -1. Columns were planted with 'Kentucky 31' tall rescue (Festuca arundinacea Schreber). Leachate analyses and pH determinations from column mixes were done at the beginning and the conclusion of the experiments. Both FGD by-products were effective in raising pH of the spoil materials. The largest LIMB amendment raised pH to near 12 and resulted in the formation of ettringite [(Ca 6Al 2(SO 4) 3(OH) 12 · 26 H 2O)]. Leachate pH, electrical conductivity, dissolved organic C, Ca, Mg, and S tended to increase with increased FGD amendment, while Al, Fe, Mn, and Zn decreased. Changes in leachate As, B, Cu, Ni, and Se depended on interactions among the type of FGD, the type of spoil, and the presence of sewage sludge, with pH being the most important variable. Overall, with FGD amendments of 120 g kg -1 or less, leachate concentrations of most elements of environmental concern were less than drinking water standards. The amount of FGD by-product that can be applied to a minespoil is probably limited by soluble salts and initially high pH levels rather than by trace element loading of spoil or water.

Abandoned mine lands containing pyritic spoil may become toxic due to production of sulfuric acid and subsequent high levels of heavy metals. A field study was initiated to compare the long-term (10 yr) effectiveness of digested municipal sewage sludge (224 Mg ha -1), powerplant fly ash (448 Mg ha -1), papermill sludge composted with either coarse or fine wood bark (67, 90, and 112 Mg ha -1), and limed topsoil (20-cm depth) in maintaining a grass-legume mixture on toxic abandoned mine spoil (initial pH 3.4). Management of reclaimed plots included an additional one-time application of N, P, and K according to soil test 1 yr after reclamation and annual cutting of vegetation that was either removed from the plot or left on the surface. Soil was sampled at depths of 0 to 10 and 10 to 20 cm, with the lower sample representing soil (except for the topsoil treatment) to which the amendments had not been mixed. These soil samples were analyzed for pH and plant nutrients. Dry matter production declined sharply after 3 yr and then recovered the last 2 yr due to favorable weather, although to only two- thirds of the initial levels. The topsoil and sewage sludge amendments maintained overall highest yields and highest percent vegetative cover (93 and 91%, respectively). Amended spoil experienced a gradual pH increase over the study period with the topsoil amendment exhibiting the highest pH (7.0) and fly ash the lowest pH (5.1) after 10 yr. The topsoil and sewage sludge amendments generally maintained the highest soil K, Ca, and Mg concentrations, while the sewage sludge and fly ash amendments had the highest P concentrations. pH values and P, K, Ca, and concentrations in the 0- to 10-cm soil horizon were higher than in the 10- to 20-cm horizon. Management did not result in differences in plant uptake of nutrients and metals, but a one-time addition of lime and fertilizer did increase vegetative yields. We conclude that the papermill sludge and sewage sludge amendments were roughly equivalent to limed topsoil for the successful long- term reclamation of toxic mine spoil. The fly ash amendment was least successful due to its inability to provide pH and nutrient levels sufficient for the maintenance of good vegetative growth.

Dry flue gas desulfurization (FGD) byproducts result from the removal of SO2 from the stack gases of coal-fired boilers and are mixtures of coal fly-ash, CaS04 and unspent sorbent. Dry FGD byproducts frequently have neutralizing values greater than 50% CaC03 equivalency and thus have potential for neutralizing acid agricultural soils. Owing to the presence of soluble salts and various trace elements, however, soil application of dry FGD byproducts may have adverse effects on plant growth and soil and water quality. The use of a dry FGD by-product as a limestone substitute was investigated in a field study on three acid agricultural soils (pH 4.6,4.8, and 5.8) in eastern Ohio. The by-product (60% CaC03 equivalency) was applied in September, 1992, at rates of 0,0.5, 1.0, and 2.0 times the lime requirement of the soils, and alfalfa (Medicago sativa L.) and corn (Zea mays L.) were planted. Soils were sampled in April, 1993 and analyzed for pH and water soluble concentrations of 28 elements. Soil pH was increased by all FGD rates in the zone of incorporation (0-10 an), with the highest rates giving a pH slightly above 7. At 10- to 20-cm, pH was increased from 4.7 to 5.2 in two soils; there was no effect on pH at 20- to 30-cm. Calcium, Mg, and S increased, and Al, Mn, and Fe decreased with increasing dry FGD application rates. No trace element concentrations were changed by dry FGD application except B which was increased in the zone of incorporation. Dry FGD increased alfalfa yield on the most acidic soil, and decreased corn grain yield on another soil. Application of dry FGD equivalent to the lime requirement of acid soils appears to be beneficial to acid-sensitive crops such as alfalfa. No detrimental effects on soil quality were observed in this study.

This chapter elaborates the reclamation of acidic mined lands in humid areas. A primary objective in plans for achieving satisfactory reclamation is to establish a permanent vegetative cover. Establishment of vegetation on abandoned mined lands is often hindered by low availability of plant nutrients and soil moisture, and by unstable slopes due to hilly terrain. Spoilbanks consist of a heterogeneous mixture of the overburden strata. The composition of the overburden material and the type of mining and reclamation will thus have a large influence on the physical properties found at the surface of a given spoilbank. Acidic mined lands exhibit reduced biological activity compared to undisturbed soils. Biological activity is important for the breakdown of litter so that plant nutrients can be released and recycled within the ecosystem, and for improving soil physical properties. Covering spoil with topsoil can be used to establish vegetation. It is found that when topsoil is used to cover toxic spoil, the nutrient status can be determined by a soil test. Based on this information, the approximate quantity of nutrients required for good plant growth can be calculated. Large quantities of sewage sludge have also been used to establish vegetation on toxic spoils. The seeding and management of amendment-treated spoil are also described.

Dry flue gas desulfurization (FGD) by-products are mixtures of coal fly-ash, anhydrite (CaCOâ), and unspent lime- or limestone-based sorbent. Dry FGD by-products frequently have neutralizing values greater than 50% CaCOâ equivalency and thus have potential for neutralizing acidic soils. Owing to the presence of soluble salts and various trace elements, however, soil application of dry FGD by-products may have adverse effects on plant growth and soil quality. The use of a dry FGD by-product as a limestone substitute was investigated in a field study on three acidic agricultural soils (pH 4.6, 4.8, and 5.8) in eastern Ohio. The by-product (60% CaCOâ equivalency) was applied in September, 1992, at rates of 0, 0.5, 1.0, and 2.0 times the lime requirement of the soils, and alfalfa (Medicago sativa L.) and corn (Zea mays L.) were planted. Soils were sampled immediately after FGD application and three more times every six months thereafter. Samples were analyzed for pH and water soluble concentrations of 28 elements. Soil pH was increased by all FGD rates in the zone of incorporation (0--10 cm), with the highest rates giving a pH slightly above 7. Within one year pH increases could be detected at depths up to 30 cm. Calcium, Mg, and S increased, and Al, Mn, and Fe decreased with increasing dry FGD application rates. No trace element concentrations were changed by dry FGD application except B which was increased in the zone of incorporation. Dry FGD increased alfalfa yield on all three soils, and had no effect on corn yield. No detrimental effects on soil quality were observed.