Doctor of Philosophy, The Ohio State University, 2014, Environmental Science

Increasing proportions of vacant land parcels in post-industrial cities is a growing concern due to decreasing land value and increasing maintenance externalities. Utilizing this urban vacant land for growing food crops can promote local self-reliance and access to healthy food; specifically in low income disadvantaged neighborhoods. However, impact of heavy metal contaminants on soil quality, is a major concern for urban agriculture. Additionally, health of vacant lot soil also depends on the structural bio-diversity of the below ground soil food web. Hence the specific objectives of this research were (i) to assess the level of soil heavy metal concentrations in two post-industrial cities and determine their potential human health risk (Chapter 2); (ii) to evaluate the relationship between heavy metal concentrations and the structure and function of the soil food web using nematodes as surrogates of soil microbial community (Chapter 3); (iii) to test a novel approach of transplantation of an intact soil core to reconstruct the structural complexity of a disturbed soil food web and restore its level of multi trophic interactions to a pre-disturbance level (Chapter 4) (iv) finally, to re-construct the soil food web in urban vacant lot using intact soil cores from relatively undisturbed forest soil, and assess the survival of the introduced nematode species under organic matter with different C:N ratios (Chapter 4) We determined the extent of soil Pb, Cd, Zn, As and Cr concentrations in 43 vacant lots in two disadvantaged neighborhoods in Hough (Cleveland) and Weinland Park (Columbus), Ohio. Results showed that compared to the Ecological Soil Screening levels (Eco SSL) for human ingestion of soil, only 6% of the lots in Weinland Park and 53% in Hough neighborhood had Pb concentrations above the Eco SSL of 400 mg Pb/kg soil. Also, all the studied sites exceeded the Eco SSL value of 0.4 mg As/kg soil; however, soil As concentration in 94% of the lots in Weinl (open full item for complete abstract)

Committee: Parwinder Grewal Dr. (Advisor); Larry Phelan Dr. (Committee Member); Nick Basta Dr. (Committee Member); Rafiq Islam Dr. (Committee Member) Subjects: Environmental Science

Doctor of Philosophy, The Ohio State University, 2009, Environmental Science

Human activities involved with urban development have substantial impact on soil. This work examined anthropogenic influences measured by changes in soil profile, length of urbanization period, and the distance from paved roads on soil ecosystems, specifically on the size of key soil nutrient pools, and the abundance and diversity of soilborne nitrogen fixing bacteria and soil nematodes. Further spatial organization of the urban soil nematode community was described at functional guild and taxonomic level to explore ways to improve the value of nematodes as bioindicators. First, experimental plots with four different soil matrixes which are commonly found in newly developed urban sites (topsoil, compost amended topsoil, subsoil and compost amended subsoil) were established. The abundance and diversity of soilborne nitrogen fixing bacteria using gene marker, nifH were monitored for one-year period after tall fescue lawn establishment. Initially, abundance of nifH measured by quantitative polymerase chain reaction was significantly lower in subsoil compared to topsoil, but it enriched quickly to the level in topsoil over a one year period. However, the composition of nifH differed between topsoil and subsoil plots. Second, the sizes of key soil nutrient pools were measured and compared along temporal and spatial gradients related to urban development. Study sites were selected from same land use type; turfgrass-covered soils in public schools. Total soil carbon, nitrogen, organic matter, pH, and exchangeable Ca varied in a predictable manner with duration of urbanization and distance from paved roads. To evaluate the potential of soil nematodes as indicators for detecting differences in urban soil chemistry, soil nematodes were extracted, counted, and identified to the genus level. Along the urbanization duration gradient, soil nematode abundance and diversity indices clearly reflected differences in soil chemistry. The abundance of soil nematodes in road-side soils w (open full item for complete abstract)

Committee: Parwinder Grewal PhD (Advisor); John Cardina PhD (Committee Member); Richard Dick PhD (Committee Member); Edward McCoy PhD (Committee Member); Brian McSpadden Gardener PhD (Committee Member) Subjects: Ecology

Doctor of Philosophy, The Ohio State University, 2007, Environmental Science

Turfgrass lawns are a central part of urban and suburban landscapes throughout North America. Although they provide numerous benefits, urban lawns have become chemical input intensive systems with routine application of fertilizers and pesticides. These inputs are expensive and are considered a source of environmental pollution and health risk. However, very little is known about the impacts of chemical inputs on turfgrass soil ecology and ecosystem functioning. Our four objectives in this study were to: 1) compare turfgrass establishment, nutrient pools, and nematode community in subsoil and topsoil, with or without compost amendment; 2) determine the effects of nitrogen fertilization on turfgrass soil nematode community and nutrient pools; 3) determine long-term effects of management practices on turfgrass soil nematode community and nutrient pools; and 4) assess the influence of three predominant home lawn management programs on turfgrass quality, weed and insect infestations, disease incidence, and soil food web structure and functions. We found topsoil had higher initial soil nutrients and biota and thus higher turfgrass germination than subsoil. However, higher weed infestation in topsoil plots due to weed seed bank suggested that weed control was important during the early stage of turfgrass establishment on topsoil. Also, compost amendment was an effective way to improve soil nutrient pools and biota, and its impact on soil ecosystem remained during the study period. Long-term organic-fertilizer management benefited soil ecosystem in general compared to mineral-fertilizer management. However, pesticide applications had no significant effect on soil microbial biomass and soil organic matter (SOM) over long term. Nitrogen application could impose long-term cumulative effect on turfgrass soil food web rather than short-term impact. Turfgrass soil nematode food web was highly enriched but poorly to moderately structured irrespective of the management practices u (open full item for complete abstract)

Committee: Parwinder Grewal (Advisor) Subjects: