Effect of Organic Amendments on Phosphorus Fractionation in a Lead-Contaminated Urban Soil Abstract: A sequential phosphorus extraction scheme was applied to a lead-(Pb) contaminated soil in Herculaneum, MO for both a field and incubation study. The objectives of this project were; (1) lower soil P fixation and retention through the addition of organically amended P sources; (2) identify the distribution of P among five operationally defined pools of extractable phosphate following treatment incorporation; (3) determine portion of labile P derived from vermicompost (VC); and (4) identify treatments that could potentially lower bioaccessible Pb over an eight-week period. Sequential fractionation identified the Aluminum-associated P (Al-P) fraction as the fraction responding the most to treatment addition. Retention as Al-P could be effectively reduced using the organic amendments evaluated in this study in combination with VC. Amended triple super phosphate (TSP) and VC lowered bioaccessible Pb concentration compared to a non-amended plot. This finding may provide some experimental justification for the application of VC in combination with TSP to Pb-contaminated soil. Further research focusing on a combination of these P sources applied to Pb-contaminated soil could elucidate the conclusion postulated by this research.

<p>Cape Town includes two vegetable farming areas within the city limits, the Joostenbergvlakte/Kraaifontein area and the Philippi area. Both areas supply produce to local markets and further afield. Sporadically, high levels of cadmium, copper, lead and zinc have been found to occur in some of the soils, irrigation water resources and crops. To find the sources of specifically Cd, Pb and Zn to these agricultural systems, extensive analysis of several heavy metals in inputs such as fertilizers, agrochemicals and supplementary water resources to these farming areas was undertaken. Heavy metal concentrations in soils, irrigation water resources and crops were also determined. Two mitigation techniques that could be used to remediate Cd, Pb and Zn contamination were investigated. The first mitigation method included immobilization of heavy metals as phosphate complexes by using a triple super phosphate fertilizer, while the second method involved mobilisation and thus leaching of heavy metals away from plant roots using EDTA. These mitigation methods were tested in a pot experiment using cabbage as the experimental crop and soil from these areas as growth medium. A survey of common farming practices in these two areas and farmers willingness to use remediation methods was conducted.</p>

<p>Cape Town includes two vegetable farming areas within the city limits, the Joostenbergvlakte/Kraaifontein area and the Philippi area. Both areas supply produce to local markets and further afield. Sporadically, high levels of cadmium, copper, lead and zinc have been found to occur in some of the soils, irrigation water resources and crops. To find the sources of specifically Cd, Pb and Zn to these agricultural systems, extensive analysis of several heavy metals in inputs such as fertilizers, agrochemicals and supplementary water resources to these farming areas was undertaken. Heavy metal concentrations in soils, irrigation water resources and crops were also determined. Two mitigation techniques that could be used to remediate Cd, Pb and Zn contamination were investigated. The first mitigation method included immobilization of heavy metals as phosphate complexes by using a triple super phosphate fertilizer, while the second method involved mobilisation and thus leaching of heavy metals away from plant roots using EDTA. These mitigation methods were tested in a pot experiment using cabbage as the experimental crop and soil from these areas as growth medium. A survey of common farming practices in these two areas and farmers willingness to use remediation methods was conducted.</p>

Philosophiae Doctor - PhD / Cape Town includes two vegetable farming areas within the city limits, the Joostenbergvlakte/Kraaifontein area and the Philippi area. Both areas supply produce to local markets and further afield. Sporadically, high levels of cadmium, copper, lead and zinc have been found to occur in some of the soils, irrigation water resources and crops. To find the sources of specifically Cd, Pb and Zn to these agricultural systems, extensive analysis of several heavy metals in inputs such as fertilizers, agrochemicals and supplementary water resources to these farming areas was undertaken. Heavy metal concentrations in soils, irrigation water resources and crops were also determined. Two mitigation techniques that could be used to remediate Cd, Pb and Zn contamination were investigated. The first mitigation method included immobilization of heavy metals as phosphate complexes by using a triple super phosphate fertilizer, while the second method involved mobilisation and thus leaching of heavy metals away from plant roots using EDTA. These mitigation methods were tested in a pot experiment using cabbage as the experimental crop and soil from these areas as growth medium. A survey of common farming practices in these two areas and farmers willingness to use remediation methods was conducted. / South Africa