Electronic Theses and Dissertations

Award/Availability

Open Access Thesis

Keywords

Water--Pollution--Iowa--Dry Run Creek (Black Hawk County;, Land cover--Iowa--Dry Run Creek (Black Hawk County);

Abstract

The study was done in Dry Run Creek watershed, a small sub-urban watershed in the northwestern part of Black Hawk County, Iowa. Different hydrologic units like, wetland, agricultural area, urban area, and stream channels were compared in terms of nutrient transport. Soil, surface water, and groundwater samples were collected from May, 2012 to October, 2012. Among the hydrologic units, agricultural land has the highest organic matter percentages, infiltration rate, soil nitrate, and total phosphorus. High infiltration rate and amount of nutrients in agricultural soil made those areas more vulnerable to vertical infiltration of pollutants. Agricultural and urban soils had similar organic matter percentages. A constructed wetland in the study area is actively recycling nutrients from its surface water. Stream bank soil has low nitrate and phosphorus but high chloride compared to other units. In general nitrate and total phosphorus concentrations are high during the months of agricultural activities (May-July), indicating active influx from agricultural lands. Urban areas contribute significant amount of phosphorus and total suspended sediment into the stream. Spatial and temporal variations of nutrients in soil and water indicate active recycling of nutrients within the watershed and their interactions with other hydrologic units. Nutrient distribution in soil at different depth profiles indicates active vertical movement of nutrients. Though agricultural soil has high nitrate compared to urban areas, groundwater from urban areas shows high dissolved nitrate compared to agricultural areas. Total nitrate-N, phosphorus, and TSS load leaving the watershed in three months (June-August) was calculated as 2.5x105 kg, 594 kg, and 2.2x105 kg respectively. During the study period precipitation was very low and the year was unusually dry. Repetition of the study in a year of greater rainfall will give valuable information regarding the consistency of the results and effects of dry weather in nutrient transport.

Date of Award

2013

Degree Name

Master of Science

Department

Environmental Science Program

First Advisor

Mohammad Z. Iqbal

Date Original

2013

Object Description

1 PDF file (xii, 146 pages)

Language

EN

File Format

application/pdf

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