The influence of agriculture on groundwater quality : a hydrogeological and geochemical perspective / by Janie B. Williams.
| Author/creator | Williams, Janie B. author. |
| Other author | Spruill, Richard K., degree supervisor. |
| Other author | East Carolina University. Department of Geology. |
| Format | Theses and dissertations |
| Production | 1998. |
| Description | 33 leaves : illustrations (some color) ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | The purpose of this thesis is to study how agriculture affects the surficial aquifer of the Pete Mitchell Swamp Drainage Basin (Pete Mitchell Basin) in terms of its hydrogeology and geochemistry. The hydrogeologic framework was initially developed from previous studies and field data (1993-1995) from wells and surface-water sites. Water-level measurements were taken manually and with analog-to-digital recorders (ADRs) to determine groundwater movement in the surficial aquifer, which is from north to south with a seasonal water-table fluctuation of 4.5 feet (ft). An annual mean groundwater discharge of 9.01 inches (in.) for a given unit of area was calculated with stream-flow records. Latitude, longitude, and altitude data were collected with Global Positioning System (GPS) technology and the Pentax Electronic Total Station (Total Station). Constant-rate aquifer test and slug tests were performed to determine the aquifer characteristics of transmissivity (7), hydraulic conductivity (AT, storativity (S), and specific yield (Sy). T [2452 - 290.2 ft2/day (ft2/d)] and horizontal conductivity, or Kh (181.9 - 20.92 ft/d), values are typical of coarse clean sand to clean medium or silty sand. S (2.087 x 10-7 - 9.031 x 10-6) and Sy (4.446 x 10-5 - 1.781 X 10-3) are more representative of confined aquifer systems. Water samples were collected in 1993 from the surficial aquifer and generally occurred in the calcium sulfate hydrogeochemical facies. The samples were also assessed along a flow path in an agricultural area, providing data about chemical changes downgradient in the aquifer. The lithology of the aquifer (quartz, minor plagioclase and potassium feldspar) has a minor impact on groundwater chemistry. However, groundwater samples from surficial aquifer along the flow path had elevated sulfate, calcium, and nitrate concentrations relative to samples from nonagricultural sites. Nitrate concentrations along the flow path were above the maximum contaminant level (MCL) for U.S. Environmental Protection Agency (USEPA) drinking water standards. A potential source of these elevated concentrations is agricultural applications. Dissolution of solid fertilizers increases the concentration and variety of ions in groundwater. Concentrations of sulfur and nitrogen species from fertilizers may also change according to the redox state of the system. |
| General note | Submitted to the faculty of the Department of Geology. |
| General note | Advisor: Richard K. Spruill |
| Dissertation note | M.S. East Carolina University 1998 |
| Bibliography note | Includes bibliographical references (leaf 33). |
| Genre/form | dissertations. |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |
Availability
| Library | Location | Call Number | Status | Item Actions |
|---|---|---|---|---|
| Joyner | University Archives | ASK AT SPECIAL COLLECTIONS DESK | ✔ Available | Request Material |
| Electronic Resources | Access Content Online | ✔ Available |