A Site-Specific Approach for the Evaluation of Natural Attenuation at Metals-Impacted Sites

Brady, Warren D.; Eick, Matthew J.; Grossl, Paul R.; Brady, Patrick V.

doi:10.1080/713610988

Cited by 11 publications

(10 citation statements)

References 31 publications

(30 reference statements)

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“…data). The strength of the SEP increases with each step of the procedure, thus, metals associated with the fractions from initial steps are considered more readily available than those associated with fractions from later steps (Brady et al 2003). However, caution must be exercised when interpreting SEP data, and supplemental chemical characterization (i.e., carbonate equivalent, clay mineral analysis) may be required to aid in interpretation.…”

Section: Root Exudatesmentioning

confidence: 98%

“…Plant roots release a number of substances, such as chelates and acidifiers, into the soil to increase the availability of various nutrients (Marshner 1995). Sequential extraction procedures (SEP) (Amacher 1999) can be used to assess shifts in soil chemistry from unavailable to available forms associated with the presence of specific plant species (Brady et al 2003;Morris, unpubl. data).…”

Section: Root Exudatesmentioning

confidence: 99%

“…In order to assess changes in rhizosphere chemistry associated with suspect plants, specifically changes in element bioavailability, sequential extraction procedures (SEP) can be used. Brady et al (2003) present several case studies were SEPs were used to evaluate metal chemistry in soils at impacted sites.…”

Section: Criteria For Determining Elemental Allelopathymentioning

confidence: 99%

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Elemental allelopathy: processes, progress, and pitfalls

2008

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Allelopathic interference between plants has generally been discussed in terms of the production of toxic complex biochemicals; however, complex biochemicals may not be the only substances plants use to interfere with one another. It has also been suggested that inorganic elements may be used in an allelopathic manner. If, through phytoenrichment or root exudates, a plant is able to increase the bioavailable levels of a particular element and tolerate the levels better than its neighbors, it can produce an allelopathic effect. Elemental allelopathy has been implicated as the cause for the success of a number of invasive weeds, including Acroptilon repens, Tamarix spp., Halogeton glomeratus, Salsola iberica, and Mesambryenthemum crystallinum. Phytoenrichment of elements can occur through hyperaccumulation and litter deposition and by altering rhizosphere chemistry. Reported cases of elemental allelopathy have involved three types of elements: heavy metals and soluble salts in terrestrial systems and elemental S in aquatic systems. For the most part, studies that have reported elemental allelopathy have been inconclusive. In order to prevent overreaching conclusions in the study of biochemical allelopathy, criteria were set that can be adapted to the study of elemental allelopathy. Of the studies reviewed, the most common criteria left uninvestigated were whether the plant was actually responsible for changing the concentration of the element and whether the increased levels of an element negatively affected other species. If the study of elemental allelopathy is to avoid the same problems often associated with the study of biochemical allelopathy, these criteria should be included in investigations of elemental allelopathy.

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Section: Root Exudatesmentioning

confidence: 98%

Section: Root Exudatesmentioning

confidence: 99%

Section: Criteria For Determining Elemental Allelopathymentioning

confidence: 99%

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Elemental allelopathy: processes, progress, and pitfalls

2008

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“…The modified version of the three-step procedure proposed and validated by the BCR (Community Bureau of Reference; Ure et al 1993;Sahuquillo et al 1999) has a significant potential for being accepted as the standard method by laboratories working in the area of trace metal operationally defined fractionation. Although the information of the BCR procedure is operationally dependent, its application to field samples taken at different stages after a contamination event may also give valuable information about dynamic processes in soils (Brady et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Metal speciation studies in the aquifer sediments of Semria Ojhapatti, Bhojpur District, Bihar

Kumar

Ramanathan

Prabha

et al. 2011

Environ Monit Assess

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The pollution of aquifer sediments by heavy metals has assumed serious concern due to their toxicity and accumulative behavior. Changes in environmental conditions can strongly influence the behavior of both essential and toxic elements by altering the forms in which they occur and therefore quantification of the different forms of metal is more meaningful than total metal concentrations. In this study, fractionation of metal ions in aquifer sediments of Semria Ojhapatti area, Bhojpur district, Bihar has been studied to determine the ecotoxic potential of metal ions. The investigations suggest that iron, copper, and arsenic have a tendency to remain associated in the following order residual > reducible > acid-soluble > oxidizable; manganese and zinc have tendency to be associated as residual > acid-soluble > reducible > oxidizable. The risk assessment code reveals that manganese and zinc occur in significant concentration in acid-soluble fraction and therefore comes under the high risk category and can easily enter the food chain. Most of the iron, copper, and arsenic occur as immobile fraction (i.e. residual) followed by its presence in reducible fraction and would pose threat to the water quality due to changing redox conditions. The metal enrichment factor in the study area shows moderate to significant metal enrichment in the aquifer sediments which may pose a real threat in near future. The geo-accumulation index of metals also shows that the metals lie in the range of strongly contaminated (for iron at shallow depths) to moderately contaminated to uncontaminated values.

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“…In recent years, sequential extraction procedures (SEP) have been widely used to study the ageing of added Cu in soils (Brady et al, 2003;Inaba and Takenaka, 2005;Lu et al, 2005;Arias-Estevez et al, 2007;Jalali and Khanlari, 2008). Especially, Ma and Uren (1998) developed a SEP to study the long-term (430 days) ageing of zinc (Zn) added to bentonite, by which combined with X-ray diffraction (XRD) they approved the diffusion of Zn ions into hexagonal cavities of bentonite.…”

Section: Introductionmentioning

confidence: 99%

Ageing of added copper in bentonite without and with humic acid

Zhou

2009

Chemical Speciation & Bioavailability

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The ageing of metals in soils plays an important role in assessing ecological risk and soil quality criteria, it therefore is necessary to understand the ageing processes. Using a sequential extraction procedure and a parabolic diffusion equation, the ageing of added copper(Cu) in bentonite without and with humic acid (HA) was investigated as a function of incubation time over one year. At the same time, the effect of pH on Cu ageing in bentonite with HA was also studied. The most labile Cu fractions (water-soluble Cu, Cu extracted by NH 4 NO 3 and EDTA) gradually transformed into less extractable forms. The modelled diffusion equation suggested that the ageing processes were controlled by surface nucleationyprecipitation and diffusion. In the presence of HA, the contribution from surface nucleationyprecipitation increased significantly, whereas that from diffusion decreased, this indicated the addition of HA significantly enhanced the short-term ageing by complexation with Cu ions, but strongly inhibited the further diffusion of Cu ions into interlayer of bentonite during long-term ageing owing to the more stable complexes formed on solid surface. With increasing pH in bentonite with HA, the apparent diffusion rate coefficient (Dyr 2 ) increased greatly, which showed that during long-term ageing pH played an important role in reducing the extractability as a result of the significant increase in residual Cu (RES-Cu), the most inert fraction, due to micropore diffusion.

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A Site-Specific Approach for the Evaluation of Natural Attenuation at Metals-Impacted Sites

Cited by 11 publications

References 31 publications

Elemental allelopathy: processes, progress, and pitfalls

Elemental allelopathy: processes, progress, and pitfalls

Metal speciation studies in the aquifer sediments of Semria Ojhapatti, Bhojpur District, Bihar

Ageing of added copper in bentonite without and with humic acid

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