| dc.description.abstract | Spring flooding of the Red River of the North is a common phenomenon, but no
infonnation exits on how these flooding events impact both water and sediment quality
within an urban area. The objectives of this study were to assess if urban enviromnents
affect floodwater quality and to determine the quality of sediment deposited in an urban
environment after floodwaters recede. Water samples were taken on 12 dates from two
locations before and after the city limits of Pargo, North Dakota and Moorhead, Minnesota
(F-M), and were measured for 12 variables including total sediment, P04, 17/3-estradiol,
and diesel range organics. Sediment and underlying soil samples were collected from three
locations within F-M where, at each location, there were three equidistant transects parallel
to the river channel, and analyzed for 40 variables including dry sediment mass, carbon,
nitrogen, diesel and gasoline range organics, and trace elements. Considering river
discharge and total sediment and P04 concentrations at each sampling date, about 4500 Mg
of sediment and 30 Mg of P04 were estimated to have been deposited within F-M. l 7Bestradiol was detected in 9 of 24 water samples with an average concentration of0.61 ng L1 and diesel range organics were detected in 8 of 24 samples with an average concentration
of 80.0 µg L-1. Average mass of sediment across locations and transects ranged from about
2 to 1 O kg m·2 where transects closest to the river channel had the higher mass deposits of
sediment. Total carbon and nitrogen within the sediment was determined to be mostly
organic and ranged from about 40 to 59 g kg' 1 and about 1,760 to 4,930 mg kg·1,
respectively, with the highest concentrations occurring at the transect furthest from the river channel. No gasoline range organics were detected, but diesel range organics were
detected in 26 of the 27 sediment samples analyzed with a maximum concentration of 49.2
µg g-1• Total Hg concentrations in the sediment and soil averaged about 55 and 61 ng g-1,
respectively, and all trace elements detected in the sediments were within ranges for noncontaminated sites. Although sediments remaining after floodwaters recede can be
unsightly and cleanup efforts can be labor intensive, these sediments can also provide
essential plant nutrients for urban riverine ecosystems, which may include turf grass, fruits
and vegetables, and horticultural plants. | en_US |
