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Remediation of heavy metal contamination in biosolids-amended soils

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Show simple item record Talebigheshlaghi, Zahra en 2010-03-18T01:35:27Z 2007 en
dc.description.abstract The Bromley Sewage Treatment Farm (BSTF) at Christchurch, NZ, has received biosolids since the late 1960's, resulting in heavy metal accumulation in the soil. The purpose of this study was to determine whether the bioavailability/mobility of heavy metals can be reduced by remediation methods involving addition of inexpensive materials to the biosolids-amended soils. Ten soils from the BSTF with a range of metal concentrations (Cu, Cr, Cd, Ni, Pb and Zn) were initially examined. Most sites have already reached the maximum recommended* heavy metal concentrations (Cu, Cd and Zn), and a significant percentage of the total metals were associated non-residual, potentially labile fractions. Three soils, representing low, medium and high levels of metal contamination (Zn, Ni, Cu and Cd) were selected for further study. Iron oxide, peat, zeolite, iron waste and treated zeolite were selected as potential amendments for reducing metal mobility/bioavailability. A comparison of metal sorption by the biosolids-amended soils and the various amendments suggested that peat, treated zeolite and iron oxide had the potential to reduce metal solubility in biosolids-amended soils. However, metal sorption increased strongly with an increase in pH, and with some amendments it may be necessary to increase soil pH by liming to obtain the most effective metal retention. Results from an incubation study revealed that, in many cases, addition of the amendments successfully reduced soluble metal concentrations in the soils. However, soluble metal concentrations in the control lowest contaminated soil were often near or below the detection limits to begin with. For the medium and highly contaminated soils, lime was the most effective material for increasing soil pH, and lime, treated zeolite and iron waste were the best amendments for immobilizing Zn, Cu and Ni, especially when the two amendments were combined with lime. Only the iron oxide reduced Cd concentrations significantly in the medium soil. A preliminary glasshouse study, showed that sunflowers have a relatively high ability to absorb heavy metals from the soil compared to a range of other plant species, and therefore sunflowers were used as the test plant in the main experiment. Using the medium and highly contaminated soils, it was demonstrated that, combinations of iron waste with lime (0.66% w/w) increased root production significantly. However, application of treated zeolite on its own suppressed dry matter production and shoot Ni, Cu and Zn uptake. The addition of lime alone (0.33% w/w) significantly increased shoot growth for the highly contaminated soil. Decreases in plant Ni and Zn concentration/uptake were observed due to application of treated zeolite or iron waste together with lime, and with some exceptions, lime or iron waste additions on their own. The proportional decreases were higher for the medium soil treatments relative to the highly contaminated soil. There were minimal effects of the various treatments on plant Cu concentration or uptake. In a root study experiment, it was shown that water-extractable Ni, Cu and Zn in rhizosphere soil generally decreased as a result of amendment with iron waste, with or without lime, and with lime alone. en
dc.format.extent 1-201 en
dc.language.iso en en
dc.publisher Lincoln University en
dc.subject heavy metals en
dc.subject iron waste en
dc.subject zeolite en
dc.subject peat en
dc.subject iron oxide en
dc.subject treated zeolite en
dc.subject sorption en
dc.subject plant en
dc.subject remediation en
dc.subject immobilization en
dc.subject bioavailability en
dc.subject pot experiment en
dc.subject rhizosphere en
dc.subject biosolids-amended soil en
dc.title Remediation of heavy metal contamination in biosolids-amended soils en
dc.type Thesis Lincoln University en Doctoral en Doctor of Philosophy en
dc.subject.marsden Fields of Research::300000 Agricultural, Veterinary and Environmental Sciences::300100 Soil and Water Sciences::300103 Soil chemistry en
dc.subject.marsden Fields of Research::300000 Agricultural, Veterinary and Environmental Sciences::300100 Soil and Water Sciences::300104 Land capability and soil degradation en
lu.contributor.unit Lincoln University en
lu.contributor.unit Faculty of Agriculture and Life Sciences en
lu.contributor.unit /LU/Agriculture and Life Sciences/SOIL en
lu.contributor.unit Soil, Plants and Ecological Sciences en
dc.rights.accessRights Digital thesis can be viewed by current staff and students of Lincoln University only. Print copy available for reading in Lincoln University Library. May be available through inter-library loan. en
pubs.organisational-group /LU
pubs.organisational-group /LU/Agriculture and Life Sciences
pubs.organisational-group /LU/Agriculture and Life Sciences/SOIL
pubs.organisational-group /LU/SPES
pubs.publication-status Published en Christchurch en

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