Text

theses

This dissertation consists of a literature review and three main chapters, all of which are central to assessing the impacts of earthworms in polluted metalliferous soils. Chapter One gives a background in earthworm ecology, summarizing the arrival of European and Asian earthworms brought to this continent. The introduction then summarizes the questions asked for this study, and gives a brief literature review of the work that has been done prior to this research. Chapter Two describes a biological survey completed through three sampling seasons, which indicate species prevalence and population density in both non-polluted fields and forests, and metal-contaminated brownfields. This survey used a standardized mustard water extraction protocol over 135 sites in Pennsylvania and New Jersey, USA. Although there was a great deal of variation in numbers across sites, both polluted and non-polluted areas contained primarily 3 species– all of which are non-native and one that is particularly invasive. A large community pot experiment is the topic of Chapter Three, where two types of plants and four earthworm species were placed in three different soil controls of low, mid, and most metal pollution loading and grown together in five-gallon (19 L) buckets for 10 weeks. The primary goals of this experiment were to assess earthworm and plant communities and their potential interactions regarding growth and metal uptake in containers with and without earthworm communities. After all plants were harvested, they were analyzed for metal content including arsenic (As), cadmium (Cd), lead (Pb), copper (Cu), and zinc (Zn). Chapter Four details a population level experiment, examining individual plants in the pots. This design removes the competition coefficient from having two different plant species together in a community-structured experiment like the previous chapter. This design used 1-gallon tall tree sapling pots with the same soil treatments (low, mid, most pollution levels) as chapter three. This experiment, however, only used one type of plant per pot, and only two species of earthworm; both of which have been very common in all sites studied for the biosurvey noted in Chapter Two. After 60 days of growth, the plants, soil and earthworms were harvested and analyzed for metal content of arsenic, chromium, copper, lead, and zinc.

ETD_8295

Ph.D.

Includes bibliographical references

by Nicholas J. Henshue

doi:10.7282/T3J1068G

ETD doctoral

The author owns the copyright to this work.