Wood pellet fly ash and bottom ash as an effective liming agent and nutrient source for rye grass (Lolium perenne L.) and oats (Avena sativa)

Fly ash (FA) and bottom ash (BA) from a softwood pellet boiler were characterized and evaluated as soil amendments. In a greenhouse study, two plant species (rye grass, Lolium perenne L. and oats, Avena sativa) were grown in three different treatments (1% FA, 1% BA, non-amended control) of a silty loam soil. Total concentrations of plant nutrients Ca, K, Mg, P and Zn in both ashes were elevated compared to conventional wood ash. Concentrations of Cd, Cr, Pb, Se and Zn were found to be elevated in the FA relative to BA and the non-amended soil. At 28 d, oat above-ground biomass was found to be significantly greater in soil amended with FA. Potassium and Mo plant tissue concentrations were significantly increased by addition of either ash, and FA significantly increased Zn tissue concentrations. Cadmium and Hg tissue concentrations were elevated in some cases. As soil amendments, either pellet ash is an effective liming agent and nutrient source, but high concentrations of Cd and Zn in FA may preclude its use as an agricultural soil amendment in some jurisdictions. Lower ash application rates than those used in this study (i.e. <1%) may still provide sufficient nutrients and effective neutralization of soil acidity.     

The influences of fly ash on stabilization for Cd in contaminated soils

Soil contaminated with potentially toxic metals (PTMs) has being a global environmental issue, which needs to be addressed on the priority basis. Fly ash (FA) is a kind of low-cost alkaline materials, which has been widely used in remediation of soil contaminated by PTMs, while the effects of FA on the stability for PTMs in contaminated farmland soil are still not clearly evaluated. In this study, cadmium (Cd) contaminated soil samples, collected from Shaanxi (SX), Hubei (HB), and Zhejiang (ZJ) province of China, were amended with FA addition (0, 1%, 2.5%, 5%, and 10% dose), and 1-year changes of Cd availability in soil samples were focused on. In addition, biological assessment method through pot culture was carried out to evaluate the reuse potential of Cd contaminated soils amended by FA. The result indicated that FA had a notable impact on decreasing the Cd mobility of SX soil (sand type), with 18.2~52.1% reduction in the DTPA extractable solution, followed by HB soil with 5.9~16.7% reduction, but no obvious effect of FA on ZJ soil (clay type) was observed. Furthermore, the results of pot experiment revealed that FA application could increase the biomass of Chinese cabbage. However, the DTPA extractable Cd in soils after planation and the Cd accumulation of plant increased. The results revealed that FA was not a promising soil stabilizer to immobilize HMs in Cd contaminated soil, and careful consideration should be given to Cd contaminated soils with FA restoration especially in their using for farmland productive due to the remaining risk of Cd bioavailability. These results also contributed to provide references for similar soil pollution remediation.

     

Acidification Remediation Alternatives: Exploring the Temporal Dimension with Cost Benefit Analysis

Acidification of soils and surface waters caused by acid deposition is still a major problem in southern Scandinavia, despite clear signs of recovery. Besides emission control, liming of lakes, streams, and wetlands is currently used to ameliorate acidification in Sweden. An alternative strategy is forest soil liming to restore the acidified upland soils from which much acidified runoff originates. This cost–benefit analysis compared these liming strategies with a special emphasis on the time perspective for expected benefits. Benefits transfer was used to estimate use values for sport ffishing and nonuse values in terms of existence values. The results show that large-scale forest soil liming is not socioeconomically profitable, while lake liming is, if it is done efficiently—in other words, if only acidified surface waters are treated. The beguiling logic of “solving” an environmental problem at its source (soils), rather than continuing to treat the symptoms (surface waters), is thus misleading.     

Effect of Polonite used for phosphorus removal from wastewater on soil properties and fertility of a mountain meadow

Reactive filter materials used for phosphorus (P) removal from wastewater can be disposed of as soil amendments after treatment, thus recycling P and other macro- and micro-nutrients to plants. In addition, materials with a high pH and Ca content, such as Polonite, are potential soil conditioners, which can be particularly beneficial for acid soils. Polonite previously used for on-site wastewater treatment was applied as a soil amendment to a mountain meadow. The amendment significantly increased soil pH and decreased the hydrolytic acidity, thus reducing Al toxicity risks. The effects were comparable to those of liming. No difference in yield and P uptake by meadow plants was observed. The uptake of metals was lower for amended soils, especially the uptake of Mn. Using Polonite after wastewater treatment as a soil amendment is thus a viable disposal alternative that can replace liming, when necessary, being capable of recycling P and other nutrients to meadow plants.     

Trace element inputs into soils by anthropogenic activities and implications for human health.

Trace element definition and functions, and inputs into soils from the most important anthropogenic sources, related and not related to agricultural practices, of general and local or incidental concern, are discussed in the first part of this review. Trace element inputs include those from commercial fertilizers, liming materials and agrochemicals, sewage sludges and other wastes used as soil amendments, irrigation waters, and atmospheric depositions from urban, industrial, and other sources. In the second part of the review, the most important ascertained effects of soil trace elements on human health are presented. The possible relations found between some specific soil trace elements, such as Cd, Se, As and others, and cancer incidence and mortality, and diffusion of other important human diseases are reviewed. Brief conclusions and recommendations conclude this review.     

Incubation-derived calcium carbonate equivalence of papermill boiler ashes derived from sludge and wood sources

The burning of a papermill sludge and wood mixture and landspreading the resulting ash is a potential means of disposal of papermill sludge without the use of valuable landfill space. This study evaluated the effectiveness of ashes derived from a mixture of papermill sludge and wood sources to act as an alternative liming agent. The calcium carbonate equivalence of the material was determined using a 91-day laboratory incubation test with three mineral soils and one organic horizon soil. Application rates of soil-incorporated sludge-ash ranged from 2.30 to 32.2 g per kg soil. Soil pH increased linearly with increasing sludge-ash application rate. The calcium carbonate equivalence of the material varied temporally and the average value ranged from 19% to 28%. The fraction of total P, K and Mg added with the sludge-ash and extracted from the ash-amended soils using an NH4OAc based soil test method were 2.6, 3.8 and 17.6%, respectively. The low soil test extractability of ash-derived plant nutrients suggests that this material would provide only a modest increase in plant available nutrient levels in landspread fields.     

Fertilizer-N use efficiency and nitrate pollution of groundwater in developing countries

Around 76% of the world's population lives in developing countries where more fertilizer-N is currently applied than in developed countries. Fertilizers are applied preferentially in regions where irrigation is available, and soil and climatic conditions are favorable for the growth of crop plants. Due to low N application rates during the last 3 or 4 decades, negative N balances in the soil are a characteristic feature of the crop production systems in developing countries. In the future, with increasing fertilizer-N application rates, the possibility of nitrate pollution of groundwater in developing countries will be strongly linked with fertilizer-N use efficiency. A limited number of investigations from developing countries suggest that, in irrigated soils of Asia or in humid tropics of Africa, the potential exists for nitrate pollution of groundwater, especially if fertilizer-N is inefficiently managed. In a large number of developing countries in West and Central Asia and North Africa, the small amount of fertilizer applied to soils (mostly Aridisols) that remain dry almost all the year, do not constitute a major threat for nitrate pollution of groundwater, except possibly when soils are irrigated. In Asia and the Pacific regions, where 70% of the fertilizers are used to grow wetland rice on soils with low percolation rates, leaching of nitrates is minimal. Climatic water balance and soil moisture conditions do not favor leaching of nitrates from the small amount of fertilizer-N applied to Oxisols and Ultisols in Latin America. In developing countries located in the humid tropics, attempts have not been made to correlate fertilizer-N use with nitrate level in groundwater; however, fertilizers are being increasingly used. Besides high rainfall, irrigation is becoming increasingly available to farmers in the humid tropics and substantial leaching of N may also increase.     

Steel mill waste application in soil: dynamics of potentially toxic elements in rice and health risk perspectives

Environmental Science and Pollution Research - Potentially toxic elements (PTEs) are of great concern in steel mill wastes. Therefore, in order to use them as potential fertilizers in soil, risk...     

Effect of industrial waste products on phosphorus mobilisation and biomass production in abattoir wastewater irrigated soil

This study evaluated the effect of alkaline industrial by-products such as flyash (FA) and redmud (RM) on phosphorus (P) mobilisation in abattoir wastewater irrigated soils, using incubation, leaching and plant growth (Napier grass [Pennisetum purpureum]) experiments. The soil outside the wastewater irrigated area was also collected and treated with inorganic (KH₂PO₄ [PP]) and organic (poultry manure [PM]) P treatments, to study the effect of FA and RM on P mobilisation using plant growth experiment. Among the amendments, FA showed the highest increase in Olsen P, oxalic acid content and phosphatase activity. The highest increase in Olsen P for PM treated non-irrigated soils showed the ability of FA and RM in mobilising organic P better than inorganic P (PP). There was over 85 % increase in oxalic acid content in the plant growth soils compared to the incubated soil, showing the effect of Napier grass in the exudation of oxalic acid. Both amendments (FA and RM) showed an increase in phosphatase activity at over 90 % at the end of the 5-week incubation period. The leaching experiment indicated a decrease in water soluble P thereby ensuring the role of FA and RM in minimising P loss to water bodies. FA and RM showed an increase in plant biomass for all treatments, where FA amended soil showed the highest increase as evident from FA’s effect on Olsen P. Therefore, the use of FA and RM mobilised P in abattoir wastewater irrigated soils and increased biomass production of Napier grass plants through root exudation of oxalic acid.     

Interaction of soil pH and phosphorus efficacy: Long-term effects of P fertilizer and lime applications on wheat,barley, and sugar beet

Phosphorus (P), a plant macronutrient, must be adequately supplied for crop growth. In Germany, many soils are high in plant-available P; specifically in arable farming, P fertilizer application has been reduced or even omitted in the last decade. Therefore, it is important to understand how long these soils can support sustainable crop production, and what concentrations of soil P are required for it. We analyzed a 36-year long-term field experiment regarding the effects of different P application and liming rates on plant growth and soil P concentrations with a crop rotation of sugar beet, wheat, and barley. Sugar beet reacted to low soil P and low soil pH levels more sensitively than wheat, which was not significantly affected by the long-term omitted P application. All three crop species showed adequate growth at soil P levels lower than the currently recommended levels, if low soil pH was optimized by liming. The increase in efficacy of soil and fertilizer P by reduced P application rates therefore requires the adaptation of the soil pH to a soil type-specific optimal level.     

Performance evaluation of intermediate cover soil barrier for removal of heavy metals in landfill leachate

This pilot-scale study evaluated the use of intermediate cover soil barriers for removing heavy metals in leachate generated from test cells for co-disposed fly ash from municipal solid waste incinerators, ash melting plants, and shredder residue. Cover soil barriers were mixtures of Andisol (volcanic ash soil), waste iron powder, (grinder dust waste from iron foundries), and slag fragments. The cover soil barriers were installed in the test cells' bottom layer. Sorption/desorption is an important process in cover soil bottom barrier for removal of heavy metals in landfill leachate. Salt concentrations such as those of Na, K, and Ca in leachate were extremely high (often greater than 30 gL(-1)) because of high salt content in fly ash from ash melting plants. Concentrations of all heavy metals (nickel, manganese, copper, zinc, lead, and cadmium) in test cell leachates with a cover soil barrier were lower than those of the test cell without a cover soil barrier and were mostly below the discharge limit, probably because of dilution caused by the amount of leachate and heavy metal removal by the cover soil barrier. The cover soil barriers' heavy metal removal efficiency was calculated. About 50% of copper, nickel, and manganese were removed. About 20% of the zinc and boron were removed, but lead and cadmium were removed only slightly. Based on results of calculation of the Langelier saturation index and analyses of core samples, the reactivity of the cover soil barrier apparently decreases because of calcium carbonate precipitation on the cover soil barriers' surfaces.     

Effect of fly ash on sorption behavior of metribuzin in agricultural soils

This investigation was undertaken to determine the effect of two different fly ashes [Kota and Inderprastha (IP)] amendment on the sorption behavior of metribuzin in three Indian soil types. The IP fly ash was very effective in increasing the metribuzin sorption in the soils. The sorption with IP amendment was increased by 15-92%, whereas with the Kota fly ash an increase in sorption by 13-38% was noted. The adsorption isotherms fitted very well to the Freundlich adsorption equation and, in general, slope (1/n) values less then unity were observed. Although both the fly ashes significantly decreased metribuzin desorption, the IP fly ash was comparatively more effective in retaining metribuzin in the soils. Metribuzin sorption in the IP fly ash-amended soils showed strong correlation with the fly ash content and compared to K(f)/K(d) values, K(FA) values (sorption normalized to fly ash content) showed less variation. Metribuzin sorption-desorption did not correlate to the organic carbon content of the soil-fly ash mixture. The study demonstrates that all coal fly ashes may not be effective in enhancing the sorption of metribuzin in soils to the same extent. However, among the fly ashes used in this study, the IP fly ash was observed to be significantly effective in enhancing the sorption of metribuzin in soils. This may play an important role in reducing the run off and leaching losses of the herbicide by retaining it in the soil.     

粉煤灰利用研究进展

本文对粉煤灰综合利用的研究现状进行综述。内容包括粉煤灰用于烧结砖、蒸养砖、墙体材料和水泥生产、隔热防水材料、絮凝剂和肥料制备、土壤改良和废水处理等。此外,还对从粉煤灰中回收金属矿物和炭粒等进行了讨论。     

An empirical map of critical loads of acidity for soils in Great Britain

The method used to produce a critical load map of acidity for soils in Great Britain is described. Critical loads were assigned to the dominant soil in each 1 km grid square of the UK national grid. Mineral soils were assigned a critical load based on mineralogy and chemistry, using approaches appropriate to UK conditions. Critical loads for peat soils are based primarily on a maximum acceptable reduction of peat pH, and results from laboratory equilibration studies. The map shows that soils with small critical loads (<0.5 kmol_c ha⁻¹ year⁻¹) i.e. highly sensitive to acidic deposition, dominate in the north and west of Britain; the south and east are dominated by soils with large critical loads, with small areas of more sensitive soils associated with sandy soil-forming materials. A modified critical load map illustrates the potential impact of agricultural liming on soil critical loads.     

Effect of organic fertilizers derived dissolved organic matter on pesticide sorption and leaching

Incorporation of organic fertilizers/amendments has been, and continues to be, a popular strategy for golf course turfgrass management. Dissolved organic matter (DOM) derived from these organic materials may, however, facilitate organic chemical movement through soils. A batch equilibrium technique was used to evaluate the effects of organic fertilizer-derived DOM on sorption of three organic chemicals (2,4-D, naphthalene and chlorpyrifos) in USGA (United States Golf Association) sand, a mixed soil (70% USGA sand and 30% native soil) and a silt loam soil (Typic Fragiochrept). DOM was extracted from two commercial organic fertilizers. Column leaching experiments were also performed using USGA sand. Sorption experiments showed that sorption capacity was significantly reduced with increasing DOM concentration in solution for all three chemicals. Column experimental results were consistent with batch equilibrium data. These results suggest that organic fertilizer-derived DOM might lead to enhanced transport of applied chemicals in turf soils.     

Effect of soil amendments on sorption and mobility of metribuzin in soils

Metribuzin (4-amino-6-tert-butyl-4,5-dihydro-3-methylthio-1,2,4-triazin-5-one), is weakly sorbed to soil therefore, leaches easily to lower soil profiles. Soil amendments play a significant role in the management of leaching losses of pesticides. Therefore, present study reports the effect of organic manure and fly ash amendments on metribuzin downward mobility in sandy loam soil columns. Application of animal manure [T-1(OM) and T-2(OM)] and fly ash [T-1(FA) and T-2(FA)] at 2.5% and 5.0% levels increased the metribuzin retention in the soil. Freundlich constant [K(f)(1/n)] values of metribuzin for treatments T-1(OM) and T-2(OM) were 0.70 and 1.11, respectively, which were significantly higher than the value (0.27) in natural soil (T-0). The respective values for treatments T-1(FA) and T-2(FA) were 1.80 and 4.61. Downward mobility of metribuzin was studied in packed soil columns [300 mm (l)x59 mm (i.d.)]. Both the amendments significantly reduced the downward mobility of metribuzin and affected breakthrough time and maximum concentration of metribuzin in the leachate. Leaching losses of metribuzin were decreased from 97% in natural soil (T-0) column to 64% [T-1(OM)] and 42% [T-2(OM)] for animal manure-amended columns and 26% [T-1(FA)] to 100% [T-2(FA)] for fly ash-amended columns, as metribuzin did not leach out of 5% fly ash-amended column. Study indicates that both animal manure and fly ash were quite effective in reducing the downward mobility of metribuzin in packed soil columns of a sandy loam soil.     

Influence of plant growth promoting bacteria and its mutant on heavy metal toxicity in Brassica juncea grown in fly ash amended soil

In this study a metal tolerant plant growth promoting bacteria, NBRI K28 Enterobacter sp. was isolated from fly ash (FA) contaminated soils. The strain NBRI K28 and its siderophore overproducing mutant NBRI K28 SD1 were found capable of stimulating plant biomass and enhance phytoextraction of metals (Ni, Zn and Cr) from FA by metal accumulating plant i.e. Brassica juncea (Indian mustard). Concurrent production of siderophores, Indole acetic acid (IAA) and phosphate solubilization revealed its plant growth promotion potential. The strain also exhibited 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity. In most of the cases mutant of NBRI K28, exerted more pronounced effect on metal accumulation and growth performance of B. juncea plants than wild type.     

The role of glomalin, a protein produced by arbuscular mycorrhizal fungi, in sequestering potentially toxic elements

Naturally occurring soil organic compounds stabilize potentially toxic elements (PTEs) such as Cu, Cd, Pb, and Mn. The hypothesis of this work was that an insoluble glycoprotein, glomalin, produced in copious amounts on hyphae of arbuscular mycorrhizal fungi (AMF) sequesters PTEs. Glomalin can be extracted from laboratory cultures of AMF and from soils. Three different experiments were conducted. Experiment 1 showed that glomalin extracted from two polluted soils contained 1.6-4.3 mg Cu, 0.02-0.08 mg Cd, and 0.62-1.12 mg Pb/g glomalin. Experiment 2 showed that glomalin from hyphae of an isolate of Gigaspora rosea sequestered up to 28 mg Cu/g in vitro. Experiment 3 tested in vivo differences in Cu sequestration by Cu-tolerant and non-tolerant isolates of Glomus mosseae colonizing sorghum. Plants were fed with nutrient solution containing 0.5, 10 or 20 microM of Cu. Although no differences between isolates were detected, mean values for the 20 microM Cu level were 1.6, 0.4, and 0.3 mg Cu/g for glomalin extracted from hyphae, from sand after removal of hyphae and from hyphae attached to roots, respectively. Glomalin should be considered for biostabilization leading to remediation of polluted soils.     

Remediation of metal-contaminated soils with the addition of materials--part I: characterization and viability studies for the selection of non-hazardous waste materials and silicates

Contamination episodes in soils require interventions to attenuate their impact. These actions are often based on the addition of materials to increase contaminant retention in the soil and to dilute the contaminant concentration. Here, non-hazardous wastes (such as sugar foam, fly ash and a material produced by the zeolitization of fly ash) and silicates (including bentonites) were tested and fully characterized in the laboratory to select suitable materials for remediating metal-contaminated soils. Data from X-ray fluorescence (XRF), N₂ adsorption/desorption isotherms, X-ray diffraction (XRD) and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDX) analyses revealed the chemical composition, specific surface area and the phases appearing in the materials. A pH titration test allowed the calculation of their acid neutralization capacity (ANC). The metal sorption and desorption capacities of the waste materials and silicates were also estimated. Sugar foam, fly ash and the zeolitic material were the best candidate materials. Sugar foam was selected because of its high ANC (17 000 meq kg⁻¹), and the others were selected because of their larger distribution coefficients and lower sorption reversibilities than those predicted in the contaminated soils.     

Dolomite phosphate rock (DPR) application in acidic sandy soil in reducing leaching of phosphorus and heavy metals—a column leaching study

A column leaching study was designed to investigate the leaching potential of phosphorus (P) and heavy metals from acidic sandy soils applied with dolomite phosphate rock (DPR) fertilizers containing varying amounts of DPR material and N-Viro soils. DPR fertilizers were made from DPR materials mixing with N-Viro soils at the ratios of 30, 40, 50, 60, and 70 %, and applied in acidic sandy soils at the level of 100 mg available P per kilogram soil. A control and a soluble P chemical fertilizer were also included. The amended soils were incubated at room temperature with 70 % field water holding capacity for 21 days before packed into a soil column and subjected to leaching. Seven leaching events were conducted at days 1, 3, 7, 14, 28, 56, and 70, respectively, and 258.9 mL of deionized water was applied at each leaching events. The leachate was collected for the analyses of pH, electrical conductivity (EC), dissolved organic carbon (DOC), major elements, and heavy metals. DPR fertilizer application resulted in elevations up to 1 unit in pH, 7–10 times in EC, and 20–40 times in K and Ca concentrations, but 3–10 times reduction in P concentration in the leachate as compared with the chemical fertilizer or the control. After seven leaching events, DPR fertilizers with adequate DPR materials significantly reduced cumulative leaching losses of Fe, P, Mn, Cu, and Zn by 20, 55, 3.7, 2.7, and 2.5 times than chemical fertilizer or control. Even though higher cumulative losses of Pb, Co, and Ni were observed after DPR fertilizer application, the loss of Pb, Co, and Ni in leachate was <0.10 mg (in total 1,812 mL leachate). Significant correlations of pH (negative) and DOC (positive) with Cu, Pb, and Zn (P?<?0.01) in leachate were observed. The results indicated that DPR fertilizers had a great advantage over the soluble chemical fertilizer in reducing P loss from the acidic sandy soil with minimal likelihood of heavy metal risk to the water environment. pH elevation and high dissolved organic carbon concentration in soils after DPR fertilizer application are two influential factors.