Kukier & Chaney: Remediation of Nickel Phytotoxicity

Brassica oleracea L. var. capitata L.) and beetroot (Beta vulgaris L.) was obtained at 2075 and 4505 mg kg 1 Ni In situ remediation (phytostabilization) is a cost-effective solution in soil, respectively. On the muck soil containing 1200 for restoring the productivity of metal-contaminated soils and protection of food chains. A pot experiment with wheat (Triticum aestivum mg kg 1 Ni, the predicted marketable yield of celery L.), oat (Avena sativa L.), and redbeet (Beta vulgaris L.) was con[Apium graveolens L. var. dulce (Mill.) Pers.] was reducted to test the ability of limestone and hydrous ferric oxide (HFO) duced by 16 to 40% depending on growing season. Yield to ameliorate Ni phytotoxicity in two soils contaminated by particulate of lettuce (Lactuca sativa L.) grown in soil with 1300 emissions from a nickel refinery. Quarry muck (Terric Haplohemist; mg kg 1 Ni was increased by 8% or reduced by 36% in 72% organic matter) contained 2210 mg kg 1 of total Ni. The mineral comparison with predicted yields in various growing soil, Welland silt loam (Typic Epiaquoll), was more contaminated seasons. Nickel toxicity to agricultural crops grown in (2930 mg Ni kg 1 ). Both soils were very strongly acidic, allowing contaminated mineral soils located in the vicinity of the the soil Ni to be soluble and phytotoxic. Nickel phytotoxicity of the refinery as well as potential for remediation of these untreated muck soil was not very pronounced and could be easily soils received very little attention. confused with symptoms of Mn deficiency that occurred in this soil even with Mn fertilization. Severe nickel phytotoxicity of the untreated In situ amelioration of heavy metal toxicity, a costmineral soil prevented any growth of redbeet, the most sensitive crop; effective alternative to the replacement of contaminated even wheat, a relatively Ni-resistant species, was severely damaged. soil, may be achieved by amending soils with compoWhite banding indicative of Ni phytotoxicity was present on oat and nents that reduce metal solubility and hence phytoavaiwheat leaves grown on the acidic mineral soil. Soil Ni extracted with lability. Depending on metal, soil, and resources availdiethylenetriaminepentaacetic acid (DTPA) and 0.01 M Sr(NO3 )2 was able, a variety of amendments can be used including indicative of the ameliorative effect of amendments and correlated clay minerals, apatite, ferric and manganese hydroxy well with Ni concentrations in plant shoots. Making soils calcareous oxides, and limestone (Brown and Chaney, 2000; Mench was an effective treatment to reduce plant-available Ni and remediate et al., 1994; Chlopecka and Adriano, 1996). According Ni phytotoxicity of these soils to all crops tested. The ameliorative to King (1988), soil pH, organic matter, and Fe oxides effect of HFO was crop-specific and much less pronounced. content were the most important factors controlling Ni sorption by soils. Among them, soil pH was the primary factor controlling Ni sorption, hence governing Ni soluT long-term deposition of Ni-bearing particulate bility. Limestone has been successfully used for full or emissions originating from a Ni refinery located in partial remediation of Ni phytotoxicity in serpentine Port Colborne, southern Ontario, Canada resulted in soils rich in Ni of geogenic origin (Hunter and Vergcontamination of soils and vegetation in the vicinity nano, 1952; Crooke, 1956). An earlier study (Chaney northeast (downwind) of the refinery. Nickel concentraand Kukier, 1998) demonstrated that Ni phytotoxicity tions exceeding 10 000 mg kg 1 in the 0to 5-cm soil to oat and redbeet in Quarry muck containing 3000 mg layer were reported but this extremely high level of kg 1 of total Ni was ameliorated by the application of contamination is confined to a very limited area (Tema high rate of limestone. Amendment of ferric hydrous ple and Bisessar, 1981). Much attention has been deoxide has also shown some beneficial effect. However, voted to Ni contamination of muck soil farms in the the amendments that reduced Ni phytotoxicity induced vicinity of the refinery (Temple and Bisessar, 1981; severe Mn deficiency and prevented full remediation of Frank et al., 1982; Bisessar, 1989). Vegetable producthe contaminated Lake Plain soils that lost Mn during tion, the primary use of the muck soil, was adversely genesis (Baldwin and Johnston, 1986). affected by the emissions from the refinery. Toxicity Theoretically, if soil Ni is highly enriched by indussymptoms occurring in various vegetable crops as well trial contamination, the goal of remediation treatments as losses of marketable yield were investigated by Frank should be to reverse Ni phytotoxicity in a persistent et al. (1982). Marketable yield of radish (Raphanus satimanner. If such soils were amended with limestone to vus L.) in muck soil containing 4800 mg kg 1 of total Ni correct phytotoxicity, and limestone were not regularly was reduced by 93.2%. No marketable yield of cabbage applied to correct acidity potential generated from applied N and P fertilizers and natural processes, soil pH USDA Agricultural Research Service, Animal Manure and By-Products Lab., Beltsville, MD 20705. Received 23 Oct. 2000. *CorrespondAbbreviations: DTPA, diethylenetriaminepentaacetic acid; HFO, hying author ([email protected]). drous ferric oxide; limestone, a mixture of reagent-grade Ca and Mg carbonates (4.8:1, w/w). Published in J. Environ. Qual. 30:1949–1960 (2001). 1950 J. ENVIRON. QUAL., VOL. 30, NOVEMBER–DECEMBER 2001 measured in a 1:2 soil and water (by volume) slurry after 1 h would slowly fall and allow the sorbed Ni to be solubiof equilibration. Particle size distribution was determined by lized and again induce Ni phytotoxicity. A justifiable hydrometer method after removal of organic matter (Gee and alternative to soil removal and replacement is to make Bauder, 1986). The properties of the soils used are presented the soil calcareous to inactivate soil Ni by application in Table 1. Quarry and Welland are the predominant soil of a very high rate of limestone so that future pH decline series contaminated by the Ni refinery. The total Ni levels in is very unlikely in terms of centuries. Buffering soil pH Quarry and Welland soils collected for our study were 2210 at a high level with limestone is the single most effective and 2930 mg kg , respectively. This represents rather high amelioration treatment to convert soluble Ni into sorbed extent of contamination compared with the wider area with or occluded forms (nonphytotoxic) in the treated soil. recognized contamination (Kuja et al., 2001). A further reduction of soluble Ni in soil solution may Soils for the pot experiment were dried enough to allow be achieved by addition of hydrous ferric oxide (HFO), them to be sieved through a 5-mm stainless steel sieve, homogwhich can increase Ni adsorption and enhance occlusion enized, and stored moist in closed plastic containers at 4 C until amended with limestone and/or HFO and fertilizers. of Ni over time. Nickel sorption on laboratory-prepared Maintaining the soil in a nondried condition allows preservaFe oxides has been shown to increase greatly with intion of microbial activity and minimizes redox reactions of crease of pH (Bryce et al., 1994; Lo et al., 1994). Backes Fe, Mn, and other elements that occur during soil drying et al. (1995) demonstrated that metal sorption on HFO (Bartlett and James, 1980). The moisture content of the soils is affected by the specific surface area of the oxide, and was measured by oven-drying and was taken into account at is greater on amorphous than on crystalline minerals. treatment and fertilizer applications. All amendment rates Further, the crystalline Fe oxide, goethite, was found are expressed on an oven-dry soil basis. Experiments were to occlude Ni over time in a diffusion-limited process conducted in freely drained 1.5-L plastic pots holding 450 g (Bruemmer et al., 1988). Occlusion could be very signifiof the oven-dry muck soil (510 g of air-dry) and 1070 g of the cant over time as illustrated by the low fraction of oven-dry (1120 g of air-dry) mineral soil; saucers were used DTPA-extractable Ni in serpentine soils that are simulto prevent loss of leachate, and plastic mesh was used to line taneously high in Fe oxides (L’Huillier and Edighofthe drainage hole to prevent soil loss from the pots. fer, 1996). The objective of the present experiment was to test Soil Amendments the effectiveness of limestone and HFO, applied alone A mixture of powdered reagent-grade amorphous CaCO3 or in combination, in amelioration of Ni phytotoxicity and MgCO3 at 4.8:1 on a mass basis (hereafter referred to as in two soils widely differing in their properties. High “limestone”) and hydrous ferric oxide (HFO) were used as rates of Mn fertilizer were supplied to prevent limestone amendments to counteract soil Ni phytotoxicity. Limestone and HFO from inducing Mn deficiency. Soil Ni exwas applied at 0 or 50 Mg ha 1 on the basis of the pot surface tractability tests in relation to plant performance were area (0 vs. 12.7% of oven-dry weight muck soil and 0 vs. 5.3% evaluated as a tool for assessment of remediation effecof oven-dry mineral soil). The combination of Ca and Mg tiveness. carbonates was used because making a soil calcareous with only CaCO3 may cause subsequent development of Mg deficiency. Under field conditions, dolomitic limestone should be MATERIALS AND METHODS used if one plans to make an acidic soil calcareous. Amorphous Soil Collection forms of pure chemicals were used to promote very rapid ( 3 d) neutralization of soil acidity compared with commercial Remediation of an organic Quarry muck soil (Terric Haplolimestone, which may require more than 1 yr to reach equilibhemist; Canadian classification, Orthic Humic Gleysol; 72% rium pH. Hydrous ferric oxide [freshly precipitated Fe(OH)3] organic matter) and a mineral Welland silt loam soil (Typic rates were 0 and 10 Mg Fe ha 1 (2.53% Fe in the low–bulk Epiaquoll; Canadian classification, Terric Mesisol), both condensity muck soil and 1.06% in the mineral soil). Treatments taminated by particulate emissions from the Port Colborne, were combined in a factorial complete randomized block deOntario, nickel refinery, was examined in a greenhouse pot sign with four replicates. study. Soils were collected from the plow layer of previously Hydrous ferric oxide was precipitated at room temperature cropped fields. The muck soil was collected at the site of Ni by addition of NaOH to a solution of Fe(NO3 )3 in a quantity phytotoxicity evaluation studies conducted by Frank et al. exceeding the stoichiometric ratio [Fe(NO3 )3 to NaOH molar (1982) and related studies by the Ontario Ministry of the ratio of 1:3] by 3%. Upon precipitation, the HFO was washed Environment in the 1970s. Total soil Ni was determined acwith several portions of deionized water to remove NaNO3. cording to the USEPA Method 3050 using boiling HNO3 After leaching, electrical conductivity of the entrained solution (USEPA, 1995). Organic matter content was determined as was in the range of 0.05 to 0.06 mS cm 1 and the pH of the the loss on ignition by ashing the soil samples, previously dried at 105 C, in a muffle furnace at 450 C for 16 h. Soil pH was suspension was about 7.3. Table 1. Properties of soils used in the pot study. pH in water, Organic Soil Total Ni 1:2 (v/v) Sand Clay Bulk density† matter