Geology topics

W.R. Kelly

Publications and source records attributed to W.R. Kelly.

7 recordsLinked to original sources

USGS2010

Using chloride and other ions to trace sewage and road salt in the Illinois Waterway

Chloride concentrations in waterways of northern USA are increasing at alarming rates and road salt is commonly assumed to be the cause. However, there are additional sources of Cl - in metropolitan areas, such as treated wastewater (TWW) and water conditioning salts, which may be contributing to Cl - loads entering surface waters. In this study, the potential sources of Cl - and Cl - loads in the Illinois River Basin from the Chicago area to the Illinois River's confluence with the Mississippi River were investigated using halide data in stream samples and published Cl - and river discharge data. The investigation showed that road salt runoff and TWW from the Chicago region dominate Cl - loads in the Illinois Waterway, defined as the navigable sections of the Illinois River and two major tributaries in the Chicago region. Treated wastewater discharges at a relatively constant rate throughout the year and is the primary source of Cl - and other elements such as F - and B. Chloride loads are highest in the winter and early spring as a result of road salt runoff which can increase Cl - concentrations by up to several hundred mg/L. Chloride concentrations decrease downstream in the Illinois Waterway due to dilution, but are always elevated relative to tributaries downriver from Chicago. The TWW component is especially noticeable downstream under low discharge conditions during summer and early autumn when surface drainage is at a minimum and agricultural drain tiles are not flowing. Increases in population, urban and residential areas, and roadways in the Chicago area have caused an increase in the flux of Cl - from both road salt and TWW. Chloride concentrations have been increasing in the Illinois Waterway since around 1960 at a rate of about 1 mg/L/a. The increase is largest in the winter months due to road salt runoff. Shallow groundwater Cl - concentrations are also increasing, potentially producing higher base flow concentrations. Projected increases in population and urbanization over the next several decades suggest that the trend of increasing Cl - concentrations and loads will continue. Given the susceptibility of aquatic ecosystems to increasing Cl - concentrations, especially short-term spikes following snow melts, deleterious effects on riverine ecosystems would be expected. ?? 2010 Elsevier Ltd. All rights reserved.

Applied Geochemistry↗

USGS2008

Sources and fate of nitrate in the Illinois River Basin, Illinois

We conducted a two-year investigation into the sources and fate of nitrate (NO3-) in the Illinois River from the Chicago area to the river's confluence with the Mississippi River. Samples from waterways in the Chicago area (Des Plaines River and the Sanitary and Ship Canal) had relatively high concentrations of nitrogen (N) species and NO3- isotopic compositions indicative of treated wastewater (TWW). Downstream of the Brandon Road Lock and Dam, NO3- in tributaries discharging to the Illinois River primarily comes from tiles draining row crops. Nitrate isotopic signatures from these tributaries as well as drain tiles were indicative of synthetic fertilizer and/or soil organic matter (SOM) at various stages of denitrification. Nitrate-N concentrations generally decreased in the Illinois River with distance from the Chicago area primarily due to dilution. The decrease in NO3-N concentrations was especially conspicuous during the summer, when there is minimal discharge from drain tiles and NO3-N concentrations in the tributaries were low. In August 2005, when conditions were very dry, NO3-N concentrations decreased from 7.4 mg/L in the Chicago area to less than 1 mg/L near where the Illinois River discharges to the Mississippi River. The isotopic composition of NO3- in water samples from the Illinois River were a mixture of three end members: (1) fertilizer and/or SOM in drain tile water, typically showing the least amount of denitrification, (2) fertilizer and/or SOM in deeper ground water, showing the highest degree of denitrification, and (3) TWW. There was seasonal variability, depending on the volume of water flowing in the Illinois River. During high flow periods, river water samples plotted closest to those of tile drain samples; during low flow periods, a greater influence of TWW was observed in the isotopic composition. A subset of summer samples from the Chicago waterways had isotopic values plotting near and within the domain that characterizes manure and sewage. Nitrate in the Chicago area is primarily derived from TWW, with its isotopic signature evident downstream at least as far as Pekin during most of the year and all the way to the Mississippi River during periods of low flow. Denitrification occurs predominantly in groundwater between and away from drain tiles, although there is evidence that in-stream denitrification and/or biological uptake of NO3- occurs in the Peoria Lake reach of the Illinois River, at least during periods of low flow in the summer. We calculated that the river was losing about half of its NO3-N load in Peoria Lake in August 2005 (a period of very low flow), at a rate of about 7500 kg/day.

Journal of Hydrology↗

USGS2006

Estimating background and threshold nitrate concentrations using probability graphs

Because of the ubiquitous nature of anthropogenic nitrate (NO 3-) in many parts of the world, determining background concentrations of NO3- in shallow ground water from natural sources is probably impossible in most environments. Present-day background must now include diffuse sources of NO3- such as disruption of soils and oxidation of organic matter, and atmospheric inputs from products of combustion and evaporation of ammonia from fertilizer and livestock waste. Anomalies can be defined as NO3- derived from nitrogen (N) inputs to the environment from anthropogenic activities, including synthetic fertilizers, livestock waste, and septic effluent. Cumulative probability graphs were used to identify threshold concentrations separating background and anomalous NO3-N concentrations and to assist in the determination of sources of N contamination for 232 spring water samples and 200 well water samples from karst aquifers. Thresholds were 0.4, 2.5, and 6.7 mg/L for spring water samples, and 0.1, 2.1, and 17 mg/L for well water samples. The 0.4 and 0.1 mg/L values are assumed to represent thresholds for present-day precipitation. Thresholds at 2.5 and 2.1 mg/L are interpreted to represent present-day background concentrations of NO3-N. The population of spring water samples with concentrations between 2.5 and 6.7 mg/L represents an amalgam of all sources of NO3- in the ground water basins that feed each spring; concentrations >6.7 mg/L were typically samples collected soon after springtime application of synthetic fertilizer. The 17 mg/L threshold (adjusted to 15 mg/L) for well water samples is interpreted as the level above which livestock wastes dominate the N sources. Copyright ?? 2006 The Author(s).

Ground Water↗

USGS2006

Isotopic evidence of nitrate sources and denitrification in the Mississippi River, Illinois

Anthropogenic nitrate (NO3-) within the Mississippi-Atchafalaya River basin and discharge to the Gulf of Mexico has been linked to serious environmental problems. The sources of this NO 3- have been estimated by others using mass balance methods; however, there is considerable uncertainty in these estimates. Part of the uncertainty is the degree of denitrification that the NO3- has undergone. The isotopic composition of NO3- in the Mississippi River adjacent to Illinois and tile drain (subsurface drain) discharge in agricultural areas of east-central Illinois was examined using N and O isotopes to help identify the major sources of NO 3- and assess the degree of denitrification in the samples. The isotopic evidence suggests that most of the NO3- in the river is primarily derived from synthetic fertilizers and soil organic N, which is consistent with published estimates of N inputs to the Mississippi River. The 1:2 relationship between ??18O and ??15N also indicate that, depending on sample location and season, NO3- in the river and tile drains lias undergone significant denitrification, ranging from about 0 to 55%. The majority of the denitrification appears to have occurred before discharge into the Mississippi River. ?? ASA, CSSA, SSSA.

Journal of Environmental Quality↗

USGS2006

Potential effects of recurrent low oxygen conditions on the Illinois Cave amphipod

The caves of Illinois' sinkhole plain are the sole habitat of the Illinois Cave amphipod (Gammarus acherondytes), a federally endangered species. The sinkhole plain is a hydrologically-connected sequence of karstified limestone that constitutes an extensive karst aquifer which serves as an important source of potable water for area residents. During this investigation, we examined the ground-water quality in caves within two ground-water basins: 1) Illinois Caverns, where the amphipod is now present after previously reported to have been extirpated from the lower reaches, and 2) Stemler Cave, where the amphipod is reported to have been extirpated. The chemical composition of cave streams in Illinois Caverns and Stemler Cave were compared to determine which parameters, if any, could have contributed to the loss of G. acherondytes from Stemler Cave. Stream water in Stemler Cave contained higher concentrations of organic carbon, potassium, silica, chloride, fluoride, sulfate, iron and manganese than Illinois Caverns. Perhaps most importantly, dissolved oxygen (DO) concentrations in Stemler Cave were, during periods of low flow, substantially lower than in Illinois Caverns. Based on land use, there are probably at least eight times more private septic systems in the Stemler Cave ground-water basin than in the Illinois Caverns ground-water basin. Low DO concentrations were likely the result of microbial breakdown of soil organic matter and wastewater treatment system effluent, and the oxidation of pyrite in bedrock. The near-hypoxic DO in Stemler Cave that occurred during low-flow conditions, and, we speculate, a limited range of G. acherondytes within the Stemler Cave ground-water basin due to a metabolic advantage of the stygophilic aquatic invertebrates over the stygobitic G. acherodytes, resulted in the apparent loss of G. acherondytes from Stemler Cave.

Journal of Cave and Karst Studies↗

USGS2004

Nitrate and herbicide loading in two groundwater basins of Illinois' sinkhole plain

This investigation was designed to estimate the mass loading of nitrate (NO3-) and herbicides in spring water discharging from groundwater basins in an agriculturally dominated, mantled karst terrain. The loading was normalized to land use and NO3- and herbicide losses were compared to estimated losses in other agricultural areas of the Midwestern USA. Our study area consisted of two large karst springs that drain two adjoining groundwater basins (total area of 37.7 km2) in southwestern Illinois' sinkhole plain, USA. The springs and stream that they form were monitored for almost 2 years. Nitrate-nitrogen (NO3-N) concentrations at three monitoring sites were almost always above the background concentration (1.9 mg/l). NO3-N concentrations at the two springs ranged from 1.08 to 6.08 with a median concentration of 3.61 mg/l. Atrazine and alachlor concentrations ranged from <0.01 to 34 ??g/l and <0.01 to 0.98 ??g/l, respectively, with median concentrations of 0.48 and 0.12 ??g/l, respectively. Approximately 100,000 kg/yr of NO3-N, 39 kg/yr of atrazine, and 2.8 kg/yr of alachlor were discharged from the two springs. Slightly more than half of the discharged NO3- came from background sources and most of the remainder probably came from fertilizer. This represents a 21-31% loss of fertilizer N from the groundwater basins. The pesticide losses were 3.8-5.8% of the applied atrazine, and 0.05-0.08% of the applied alachlor. The loss of atrazine adsorbed to the suspended solid fraction was about 2 kg/yr, only about 5% of the total mass of atrazine discharged from the springs. ?? 2004 Elsevier B.V. All rights reserved.

Journal of Hydrology↗

USGS2001

Determination of the sources of nitrate contamination in karst springs using isotopic and chemical indicators

The sources of nitrate (NO-3) in groundwater of the shallow karst aquifer in southwestern Illinois' sinkhole plain were investigated using chemical and isotopic techniques. The groundwater in this aquifer is an important source of potable water for about half of the residents of the sinkhole plain area. Previous work has shown that groundwater from approximately 18% of the wells in the sinkhole plain has NO-3 concentrations in excess of the USEPA's drinking water standard of 10 mg N/1. Relative to background levels, the NO-3 concentrations in water from 52% of the wells, and probably all of the springs in the study area, are anomalously high, suggesting that sources other than naturally occurring soil organic matter have contributed additional NO-3 to groundwater in the shallow karst aquifer. This information, and the dominance of agriculture in the study area, suggest that agrichemical contributions may be significant. To test this hypothesis, water samples from 10 relatively large karst springs were collected during four different seasons and analyzed for inorganic constituents, dissolved organic carbon, atrazine, and ??15N and ??18O of the NO-3 ions. The isotopic data were most definitive and suggested that the sources of NO-3 in spring water are dominated by N-fertilizer with some possible influence of atmospheric NO-3 and, to a much lesser extent, human and/or animal waste. Differences in the isotopic composition of NO-3 and some of the chemical characteristics were observed during the four consecutive seasons in which spring water samples were collected. Isotopic values for ??15N and ??18O of the NO-3 ranged from 3.2??? to 19.1??? and from 7.2??? to 18.7???, respectively. The trend of ??15N and ??18O data for NO-3 also indicated that a significant degree of denitrification is occurring in the shallow karst hydrologic system (within the soil zone, the epikarst and the shallow karst aquifer) prior to discharging to springs. ?? 2001 Elsevier Science B.V. All rights reserved.

Chemical Geology↗