USGS Science⌕ Search
Home/Archive/USGS

USGS · 70022910

Herbicides and herbicide degradates in shallow groundwater and the Cedar River near a municipal well field, Cedar Rapids, Iowa

R.A. Boyd
View original source ↗Export metadata ↓

Abstract

Water samples were collected near a Cedar Rapids, Iowa municipal well field from June 1998 to August 1998 and analyzed for selected triazine and acetanilide herbicides and degradates. The purpose of the study was to evaluate the occurrence of herbicides and herbicide degradates in the well field during a period following springtime application of herbicides to upstream cropland. The well field is in an alluvial aquifer adjacent to the Cedar River. Parent herbicide concentrations generally were greatest in June, and decreased in July and August. Atrazine was most frequently detected and occurred at the greatest concentrations; acetochlor, cyanazine and metolachlor also were detected, but at lesser concentrations than atrazine. Triazine degradate concentrations were relatively small (<0.50 ??g/l) and generally decreased from June to August. Although the rate of groundwater movement is relatively fast (approx. 1 m per day) in the alluvial aquifer near the Cedar River, deethylatrazine (DEA) to atrazine ratios in groundwater samples collected near the Cedar River indicate that atrazine and DEA probably are gradually transported into the alluvial aquifer from the Cedar River. Deisopropylatrazine (DIA) to DEA ratios in water samples indicate most DIA in the Cedar River and alluvial aquifer is produced by atrazine degradation, although some could be from cyanazine degradation. Acetanilide degradates were detected more frequently and at greater concentrations than their corresponding parent herbicides. Ethanesulfonic-acid (ESA) degradates comprised at least 80% of the total acetanilide-degradate concentrations in samples collected from the Cedar River and alluvial aquifer in June, July and August; oxanilic acid degradates comprised less than 20% of the total concentrations. ESA-degradate concentrations generally were smallest in June and greater in July and August. Acetanilide degradate concentrations in groundwater adjacent to the Cedar River indicate acetanilide degradates are transported into the alluvial aquifer in a manner similar to that indicated for atrazine and DEA. Copyright (C) 2000 Elsevier Science B.V.

Explore related subjects

Conference Paper

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

R.A. Boyd. 2000. Herbicides and herbicide degradates in shallow groundwater and the Cedar River near a municipal well field, Cedar Rapids, Iowa. https://doi.org/10.1016/s0048-9697(99)00546-x

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Time-to-depth conversion of seismic-reflection data from eastern Lake Superior and implications for the eastern arm of the Midcontinent Rift

Seismic-reflection data were acquired in the mid 1980s along several lines across eastern Lake Superior by industry and the Great Lakes International Multidisciplinary Program on Crustal Evolution (GLIMPCE) (Fig. 1). The lines form part of a larger network of crossing lines over the entire lake, which can be used to develop three-dimensional geologic models of the Mesoproterozoic Midcontinent Rift that lies below. To better interpret these lines, we developed velocity models to convert seismic reflections versus two-way travel time (TWTT) to reflections versus depth. In addition, the velocity models themselves provide insights into the structure of the Midcontinent Rift by recognizing common velocity ranges for certain rock types (Grauch, 2023).

eastern Lake Superior↗
USGS2026

Revisiting the utility of regional-scale, high-quality geophysical data in mineral exploration - A case study featuring the Mammoth Magnetic Anomaly, Pinal County, Arizona

Regional aeromagnetic surveys passively measure the total magnetic intensity (TMI) and are a foundational tool used in mineral exploration (Airo, 2015). With the increased global demand and the number of critical mineral resources required for manufacturing high-tech devices, developing high-quality, regional-scale geophysical surveys could aid critical mineral exploration efforts and geologic mapping. In 2019, the U. S. Geological Survey launched the Earth Mapping Resources Initiative (Earth MRI) to modernize the geologic and geophysical mapping of regions that have the potential to contain critical mineral resources within the United States. In support of planning Earth MRI geophysical surveys, Drenth and Grauch (2019) defined five aeromagnetic data quality rankings (rank 1 through rank 5) applying them to the airborne geophysical survey inventory of the United States (Johnson et al., 2021). Rank 1 aeromagnetic surveys are of the highest quality, meeting modern standards and allowing best practices for qualitative and quantitative interpretation; whereas rank 5 aeromagnetic surveys are of the lowest quality, being useful only for qualitative interpretation of broad features. Through the Earth MRI effort, 48 high-quality, regional-scale rank 1 and 2 airborne magnetic and radiometric geophysical surveys have been planned, collected, or publicly release through May 2025 (U. S. Geological Survey, 2025). Here, a portion of a rank 1 Earth MRI aeromagnetic survey in southeast Arizona is presented and compared to a legacy rank 5 aeromagnetic survey over the Mammoth Magnetic Anomaly (MMA), demonstrating how modern, high-quality aeromagnetic data improves our view of crustal geology, aiding mineral exploration.

Arizona↗
USGS2026

Early Miocene volcanic rocks and associated tectonics, Lava Hills and southern Bristol Mountains, California

Volcanic rocks of latest Oligocene to early Miocene age form an east-west belt across part of the central eastern Mojave Desert from the Whipple Mountains on the east to the Rosamond Hills on the west. We term this the central belt because it is separated from northern and southern belts by swaths with no volcanic rocks. Limited geochronologic data indicate that much of the belt is latest Oligocene and early Miocene in age, about 24 to 19 Ma, a finding that is consistent with these rocks being overlain by the 18.8 Ma Peach Spring Tuff in many places. We describe Miocene geology in a central area of the belt, in the Lava Hills, southern Bristol Mountains, and southern Old Dad Mountains. Sedimentary basins formed coeval with early andesite to rhyolite volcanism, progressing from fluvial and lacustrine tuffaceous sandstone to volcanic lavas, tuffs, and breccias, indicating that early basins formed proximal to volcanic edifices. Higher strata are fluvial and lacustrine with lavas punctuating the sequence. Although basins may partly have been formed within topographic lows bounded by volcanic domes, plateaus, and stratovolcanoes, consistent stratigraphic sections over wide areas indicate that tectonic basin evolution affected broad areas. The volcanic section is capped by local basalt flows and the regional Peach Spring Tuff. Limited data on normal faults support interpretations of early extensional basin development caused by northeast-southwest oriented stretching. Later extension caused stratal rotations, tilting early deposits down to the southwest. This tilted and subsequently beveled basin architecture was overlain by the youngest volcanic deposits, primarily rhyolite and basalt. The Peach Spring Tuff, 18.8 Ma, lies within this upper unit. Similar stratigraphic and structural relations are exposed in the nearby Marble Mountains and Van Winkle Mountain sections, reinforcing that a broad area underwent similar volcanism and tectonism. In our study area the upper unit is only very gently tilted except near dextral strike-slip faults of the eastern California shear zone. These late Miocene to Recent faults are represented as four main fault zones spaced about 5 km apart, representing distributed shear north of the Bristol Lake basin.

California↗