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Geology topics

N.E. Peters

Publications and source records attributed to N.E. Peters.

At least 37 records · Page 2Linked to original sources
USGS1997

Spatial and temporal variability in nutrient concentrations in surface waters of the Chattahoochee River basin near Atlanta, Georgia, USA

Nutrient concentrations from the early 1970s through 1995 were evaluated at several sites along the Chattahoochee River and its tributaries near Atlanta, to determine general patterns and processes controlling nutrient concentrations in the river. A spatial analysis was conducted on data collected in 1994 and 1995 from an intensive nutrient study of the Chattahoochee River and its tributaries by the Georgia Department of Natural Resources, Environmental Protection Division. The 1994-1995 data show step increases in ammonium (NH4-N), nitrite plus nitrate (NO2 + NO3-N), and total-phosphorus (Tot-P) concentrations in the river. The step increases occur downstream of two wastewater treatment facilities (WWTFs) and Peachtree Creek, a small tributary inflow with degraded water quality draining a predominantly urban and industrial area. Median NO2 + NO3-N and Tot-P concentrations in the mainstem increase downstream of these inputs from 0.5 to 1 mg 1-1 and from 0.04 to 0.13 mg 1-1, respectively. NH4-N concentrations were typically low with 95% of the 2575 observations less than 0.2 mg 1-1 throughout the river system, except some high values (>1 mg 1-1) in some tributaries, particularly near the central part of Atlanta. High NH4-N concentrations are attributed to sewage discharge as they also are associated with high biological oxygen demand and faecal coliform bacteria concentrations. Nutrient concentrations vary temporally. An assessment of four sites, two mainstem and two tributaries, from 1970 to 1995 indicates a progressive increase and variability in NO2 + NO3-N concentrations during the period. The progressive increase in NO2 + NO3-N concentrations and their variability is similar to that reported for surface waters throughout the world and for which increased fertilizer usage has been attributed. Tot-P concentrations increase at mainstem sites through the middle to late 1980s and decrease markedly thereafter, due to improvements to WWTFs and a 1990 phosphate detergent ban. NH4-N concentrations, although less pronounced than Tot-P, display a similar decrease from the late 1980s to 1995 at the four sites. Tot-P concentration variability has increased at the tributary sites since 1993, although recent concentrations, on average, are the lowest since 1970 at each of the four sites.

IAHS-AISH Publication↗
USGS1997

Tracing hydrologic pathways at the Panola Mountain research watershed, Georgia, USA

An analysis of Cl- concentrations and fluxes at the Panola Mountain Research Watershed indicates that Cl- may be effectively used to differentiate 'new' and 'old' water flow through the hillslope and their respective contributions to streamwater. Rainfall and throughfall, the 'new' water inputs, are marked by low Cl- concentrations (15 ??eq 1-1). Stormwater moves rapidly to depth along preferred pathways in a deciduous forest hillslope, as evidenced by low concentrations (20 ??eq 1-1) in mobile soil water from zero-tension stainless-steel pan lysimeters. 'Old' waters, matrix soil waters and groundwater, typically have high concentrations (20 ??eq 1-1). Timing of soil water transport is not sufficiently rapid to suggest that soil water from the hillslope contributes to streamwater for an individual rainstorm. The source of streamflow, therefore, must be a combination of channel interception, runoff from near-channel areas, and runoff from a 3-ha bedrock outcrop in the headwaters. Groundwater contribution to streamflow was estimated using Cl- concentrations of throughfall and groundwater as the two end members for a two-component hydrograph separation. For the study period, groundwater contributed 79% of the runoff and from 1985 to 1995, contributed 75% of the runoff. Rainfall was the source of 45% of the Cl- flux from the watershed in the long term; the remaining Cl- is hypothesized to be derived from dry deposition, consistent with the enrichment noted for throughfall. At peak flow during individual rainstorms, 'new' water can contribute 95% of the runoff.

Hydrochemistry. Proc. international symposium, Rab↗
USGS1996

Trends in nutrients

The roles of nitrogen (N) and phosphorus (P) as key nutrients determining the trophic status of water bodies are examined, and evidence reviewed for trends in concentrations of N and P species which occur in freshwaters, primarily in northern temperate environments. Data are reported for water bodies undergoing eutrophication and acidification, especially water bodies receiving increased nitrogen inputs through the atmospheric deposition of nitrogen oxides (NO x ). Nutrient loading on groundwaters and surface freshwaters is assessed with respect to causes and rates of change, relative rates of change for N and P, and implications of change for the future management of lakes, rivers and groundwaters. In particular, the nature and emphasis of studies for N species and P fractions in lakes versus rivers and groundwaters are contrasted. This review paper primarily focuses on results from North America and Europe, particularly for the UK where a wide range of data sets exists. Few nutrient loading data have been published on water bodies in less developed countries; however, some of the available data are presented to provide a global perspective. In general, N and P concentrations have increased dramatically (>20 times background concentrations) in many areas and causes vary considerably, ranging from urbanization to changes in agricultural practices.

Hydrological Processes↗
USGS1995

Biotic and abiotic processes controlling water chemistry during snowmelt at rabbit ears pass, Rocky Mountains, Colorado, U.S.A.

The chemical composition of snowmelt, groundwater, and streamwater was monitored during the spring of 1991 and 1992 in a 200-ha subalpine catchment on the western flank of the Rocky Mountains near Steamboat Springs, Colorado. Most of the snowmelt occurred during a one-month period annually that began in mid-May 1991 and mid-April 1992. The average water quality characteristics of individual sampling sites (meltwater, streamwater, and groundwater) were similar in 1991 and 1992. The major ions in meltwater were differentially eluted from the snowpack, and meltwater was dominated by Ca2+, SO4/2-, and NO3/-. Groundwater and streamwater were dominated by weathering products, including Ca2+, HCO3/- (measured as alkalinity), and SiO2, and their concentrations decreased as snowmelt progressed. One well had extremely high NO3/- concentrations, which were balanced by Ca2+ concentrations. For this well, hydrogen ion was hypothesized to be generated from nitrification in overlying soils, and subsequently exchanged with other cations, particularly Ca2+. Solute concentrations in streamwater also decreased as snowmelt progressed. Variations in groundwater levels and solute concentrations indicate thai most of the meltwater traveled through the surficial materials. A mass balance for 1992 indicated that the watershed retained H+, NH4/+, NO3/-, SO4/2- and Cl- and was the primary source of base cations and other weathering products. Proportionally more SO4/2- was deposited with the unusually high summer rainfall in 1992 compared to that released from snowmelt, whereas NO3/- was higher in snowmelt and Cl- was the same. The sum of snowmelt and rainfall could account for greater than 90% of the H+ and NH4/+ retained by the watershed and greater than 50% of the NO3/-.The chemical composition of snowmelt, groundwater, and streamwater was monitored during the spring of 1991 and 1992 in a 200-ha subalpine catchment on the western flank of the Rocky Mountains near Steamboat Springs, Colorado. The major ions in meltwater were differentially eluted from the snowpack, and meltwater was dominated by Ca2+, SO42-, and NO3-. Groundwater and streamwater were dominated by weathering products and their concentrations decreased as snowmelt progressed. Solute concentrations in streamwater also decreased as snowmelt progressed. A mass balance for 1992 showed that the watershed retained H+, NH4+, NO3-, SO42- and Cl- and was the primary source of base cations and other weathering products.

Conference Paper↗
USGS1995

Variations of weekly atmospheric deposition for multiple collectors at a site on the shore of Lake Okeechobee, Florida

Eight wet/dry precipitation collectors were modified to house four additional dryfall collectors and one bulk precipitation collector to sample atmospheric deposition for 12 weeks in a small area on the southwestern shore of Lake Okeechobee; sample contamination, primarily by insects, reduced the comparison to the last nine weeks. The deposition was determined for Ca2+, Na+, Cl-, and SO42- and nutrients including total phosphorus, orthophosphate, total ammonia plus organic nitrogen, and nitrite plus nitrate. In general, deposition was lower and less variable in wet precipitation than in bulk precipitation. The higher variability of the bulk precipitation was attributed to local contamination, particularly by dust and insects. Each wet/dry precipitation collector was fitted with dryfall collectors that consisted of the dry-side bucket on a wet/dry collector, which was preloaded with distilled and deionized water, and four glass dish collectors; two of the glass dishes were preloaded with water and the other two remained dry. The deposition to the dry dish collectors was not comparable in adjacent collectors for any constituent; however, the deposition in the adjacent water-loaded dishes was comparable for most major constituents, except nutrients. A comparison of Ortho-P deposition with Total-P indicated that the P collected by the dryfall collectors was predominantly reactive, which also was reflected in the bulk deposition, whereas that in the wet deposition was mostly nonreactive. The large variability in deposition of P among the bulk and dryfall collectors suggests that alternative methods must be used to evaluate the P sources and processes of atmospheric transfer.

Atmospheric Environment↗
USGS1995

Spatial variation in background groundwater geochemistry of the Gurinai Wetland, Gobi Desert, Inner Mongolia

Age dating of groundwater from several hand-dug wells in the Gurinai Wetland of the Badajilin-Gobi Desert, north-central China, indicated a continuum from present to 7625??155 years B.P. Water age correlates with concentration for some constituents. In general, concentrations of Fe, Cr, Se and Sr increase with increasing age, whereas Ca, Br, Zn and Rb decrease. Compared to concentration ranges reported for freshwaters, several constituents were much more concentrated including Na, Cl, Mg, Br and Th, and many others extended the upper concentration limit including Sr, Mo, Rb, Cr, U, Se, Nb and Ce. For Th, the maximum observed concentration extends the previously summarized maximum by more than an order of magnitude.

Models for assessing and monitoring groundwater qu↗
USGS1993

Variations in aqueous sulfate concentrations at Panola Mountain, Georgia

Aqueous sulfate concentrations were measured in incident precipitation, canopy throughfall, stemflow, soil water, groundwater, and streamwater at three locations in a 41 ha forested watershed at Panola Mountain State Park in the Georgia Piedmont. To evaluate the variations in sulfate concentrations, sampling intensity was increased during storms by automated collection of surface water and by incremental subsampling of rainfall, throughfall, and soil solution. Canopy throughfall, stemflow, and runoff from a bedrock outcrop in the watershed headwaters were enriched in sulfate relative to incident precipitation due to washoff of dry deposition that accumulated between storms. Soil waters collected from zero-tension lysimeters at 15 cm and 50 cm below land surface also were enriched in sulfate relative to precipitation, groundwater and streamwater. Sulfate concentrations in groundwater and in streamwater at base flow varied in an annual sinusoidal pattern with winter maxima and summer minima. Stream discharge and groundwater levels varied in a similar annual pattern in phase with the sulfate concentrations. The temporal variability of sulfate concentrations at most groundwater sites was small relative to the spatial variability among groundwater sites. Streamwater sulfate concentrations during base flow were controlled by low-sulfate groundwater discharge. As flow increased, an increasing proportion of shallow, high-sulfate groundwater and soil water contributed to streamflow. The dominant control on stream sulfate concentration shifted from sulfate retention by adsorption in the mineral soil at base flow to mobilization of sulfate from the upper, organic-rich horizons of the soil at high flow.

Journal of Hydrology↗
USGS1993

Water, energy, and biogeochemical budgets investigation at Panola Mountain research watershed, Stockbridge, Georgia; A research plan

The Panola Mountain Research Watershed (PMRW), located in the Panola Mountain State Conservation Park near Stockbridge, Georgia has been selected as a core research watershed under the Water, Energy and Biogeochemical Budgets (WEBB) research initiative of the U.S. Geological Survey (USGS) Global Climate Change Program. This research plan describes ongoing and planned research activities at PMRW from 1984 to 1994. Since 1984, PMRW has been studied as a geochemical process research site under the U.S. Acid Precipitation Thrust Program. Research conducted under this Thrust Program focused on the estimation of dry atmospheric deposition, short-term temporal variability of streamwater chemistry, sulfate adsorption characteristics of the soils, groundwater chemistry, throughfall chemistry, and streamwater quality. The Acid Precipitation Thrust Program continues (1993) to support data collection and a water-quality laboratory. Proposed research to be supported by the WEBB program is organized in 3 interrelated categories: streamflow generation and water-quality evolution, weathering and geochemical evolution, and regulation of soil-water chemistry. Proposed research on streamflow generation and water-quality evolution will focus on subsurface water movement, its influence in streamflow generation, and the associated chemical changes of the water that take place along its flowpath. Proposed research on weathering and geochemical evolution will identify the sources of cations observed in the streamwater at Panola Mountain and quantify the changes in cation source during storms. Proposed research on regulation of soil-water chemistry will focus on the poorly understood processes that regulate soil-water and groundwater chemistry. (USGS)

Georgia↗
USGS1991

Chloride cycling in two forested lake watersheds in the west-central Adirondack Mountains, New York, U.S.A.

The chemistry of precipitation, throughfall, soil water, ground water, and surface water was evaluated in two forested lake-watersheds over a 4-yr period to assess factors controlling C1- cycling. Results indicate that C1- cycling in these watersheds is more complex than the generally held view of the rapid transport of atmospherically derived C1- through the ecosystem. The annual throughfall Cl- flux for individual species in the northern hardwood forest was 2 to 5 times that of precipitation (56 eq ha-1), whereas the Na+ throughfall flux, in general, was similar to the precipitation flux. Concentrations of soil-water Cl- sampled from ceramic tension lysimeters at 20 cm below land surface generally exceeded the Na+ concentrations and averaged 31 ??eq L-1, the highest of any waters sampled in the watersheds, except throughfall under red spruce which averaged 34 ??eq L-1. Chloride was concentrated prior to storms and mobilized rapidly during storms as suggested by increases in streamwater Cl- concentrations with increasing flow. Major sources of Cl- in both watersheds are the forest floor and hornblende weathering in the soils and till. In the Panther Lake watershed, which contains mainly thick deposits of till( > 3 m), hornblende weathering results in a net Cl- flux 3 times greater than that in the Woods Lake watershed, which contains mainly thin deposits of till. The estimated accumulation rate of Cl- in the biomass of the two watersheds was comparable to the precipitation Cl- flux.The chemistry of precipitation, throughfall, soil water, ground water, and surface water was evaluated in two forested lake-watersheds over a 4-yr period to assess factors controlling Cl- cycling. Results indicate that Cl- cycling in these watersheds is more complex than the generally held view of the rapid transport of atmospherically derived Cl- through the excosystem. The annual throughfall Cl- flux for individual species in the northern hardwood forest was 2 to 5 times that of precipitation (56 eq ha-1), whereas the Na+ throughfall flux, in general, was similar to the precipitation flux. Concentrations of soil-water Cl- sampled from ceramic tension lysimeters at 20 cm below land surface generally exceeded the Na+ concentrations and averaged 31 ??eq L-1, the highest of any waters sampled in the watersheds, except throughfall under red spruce which averaged 34 ??eq L-1. Chloride was concentrated prior to storms and mobilized rapidly during storms as suggested by increases in streamwater Cl- concentrations with increasing flow. Major sources of Cl- in both watersheds are the forest floor and hornblende weathering in the soils and till. In the Panther Lake watershed, which contains mainly thick deposits of till (> 3 m), hornblende weathering results in a net Cl- flux 3 times greater than that in the Woods Lake watershed, which contains mainly thin deposits of till. The estimated accumulation rate of Cl- in the biomass of the two watersheds was comparable to the precipitation Cl- flux.

Water, Air, & Soil Pollution↗
USGS1990

Modelling streamwater chemistry as a mixture of soilwater end-members - An application to the Panola Mountain catchment, Georgia, U.S.A.

Streamwater chemistry at Panola Mountain research catchment, Georgia, U.S.A., is explained as a mixture of representative soilwater solutions that are considered to be temporally invariant to a first approximation. The selection of three end-members from all sampled soil waters is evaluated by comparing the observed and predicted streamwater concentration of six solutes (alkalinity, sulfate, sodium, magnesium, calcium and dissolved silica), which are assumed to mix conservatively, and by assessing the consistency of the implied hydrograph separation with the hydrological mechanisms that are believed to be operating in this catchment. The percentage of variation in the streamwater solute concentrations explained by the end-member mixing analysis (EMMA) ranges from 82 to >97%, and the hydrograph separation is, intuitively, physically reasonable. If the correct end-members have been identified, the streamwater chemical response to different levels of acidic deposition can be predicted by examining the change in each end-member under different loads; no hydrological model is required. If a traditional hydrochemical model, which is driven by rainfall quantity and quality, is desired, this analysis provides an indication of the model structure that would be necessary to reproduce both streamwater and soilwater chemistry.

Georgia↗
USGS1988

Atmospheric deposition effects on the chemistry of a stream in Northeastern Georgia

The quantity and quality of precipitation and streamwater were measured from August 1985 through September 1986 in the Brier Creek watershed, a 440-ha drainage in the Southern Blue Ridge Province of northeastern Georgia, to determine stream sensitivity to acidic deposition. Precipitation samples collected at 2 sites had a volume-weighted average pH of 4.40 whereas stream samples collected near the mouth of Brier Creek had a discharge-weighted average pH of 6.70. Computed solute fluxes through the watershed and observed changes in streamwater chemistry during storm flow suggest that cation exchange, mineral weathering, SO 4 2− adsorption by the soil, and groundwater discharge to the stream are probable factors affecting neutralization of precipitation acidity. Net solute fluxes for the watershed indicate that, of the precipitation input, > 99% of the H + , 93% of the NH 4 + and NO 3 − , and 77% of the SO 4 2− were retained. Sources within the watershed yielded base cations, Cl − , and HCO 3 − and accounted for 84, 47, and 100% of the net transport, respectively. Although streamwater SO 4 2− and NO 3 − concentrations increased during stormflow, peak concentrations of these anions were much less than average concentrations in the precipitation. This suggests retention of these solutes occurs even when water residence time is short.

Georgia↗
USGS1988

Short-term trends in sulfate deposition at selected bulk precipitation stations in New York

Trends in rainfall-adjusted sulfate concentration were assessed for 5-yr subrecords of the 14.5–17 yr of monthly bulk-deposition data from five stations in New York by using the seasonal Kendall test. For the 5-yr subrecord from 1978 to 1982, the trends for the bulk deposition were similar to those for weekly wet-only deposition for adjacent stations of the National Atmospheric Deposition Program (NADP). The long-term trend at each of the bulk-precipitation sites was downward and statistically significant at P < 0.02, whereas 26% of the 69 subrecords had trends that were statistically significant only at P < 0.2. Of these statistically significant subrecord trends, 10% were positive (opposite to the long-term trend). Furthermore, the slopes of the subrecord trends tended to be much steeper than those of the whole record. These 5-yr trends, consequently, are poor indicators of the trends that occur over much longer periods in the same record.

New York↗
USGS1988

Preliminary observations of streamflow generation during storms in a forested Piedmont watershed using temperature as a tracer

Variations in streamwater temperature at the outlet of a 41-ha forested watershed at Panola Mountain in the Georgia Piedmont indicate that the initial rapid hydrologic response is caused by a combination of groundwater discharge and channel interception of rainwater. A storm in May 1986 caused a rapid increase in discharge that was accompanied by a decrease in streamwater temperature and a rise in the water table level adjacent to the stream. The higher water table provided the hydraulic gradient necessary to increase the discharge of colder groundwater to the stream. Storms that occurred under very dry antecedent conditions in July 1986 and June 1987 caused a rapid hydrologic response but no change in water table level, indicating the response was caused by channel interception of rainwater. This conclusion was supported by increases in streamwater temperature in the June storm and by chemical changes in the July storm. When rainfall is sufficient, flow in the ephemeral part of the stream in the catchment headwaters generates a second and larger discharge peak that reflects the chemistry and temperature of runoff from a 3-ha granite outcrop in the headwaters; sulfate concentration and temperature increase and alkalinity decreases relative to prestorm conditions. The initial response, however, results from channel interception and groundwater discharge. Rapid rises in the water table level during some storms suggest that macropore flow may play a major role in the hydrologic response of the watershed to rainstorms.

Journal of Contaminant Hydrology↗
USGS1987

Hydrogeologic controls of surface-water chemistry in the Adirondack region of New York State

Relationships between surface-water discharge, water chemistry, and watershed geology were investigated to evaluate factors affecting the sensitivity of drainage waters in the Adirondack region of New York to acidification by atmospheric deposition. Instantaneous discharge per unit area was derived from relationships between flow and staff-gage readings at 10 drainage basins throughout the region. The average chemical composition of the waters was assessed from monthly samples collected from July 1982 through July 1984. The ratio of flow at the 50-percent exceedence level to the flow at the 95-percent exceedence level of flow duration was negatively correlated with mean values of alkalinity or acid-neutralizing capacity (ANC), sum of basic cations (SBC), and dissolved silica, for basins containing predominantly aluminosilicate minerals and little or no carbonate-bearing minerals. Low ratios are indicative of systems in which flow is predominately derived from surface- and ground-water storage, whereas high ratios are characteristic of watersheds with variable flow that is largely derived from surface runoff. In an evaluation of two representative surface-water sites, concentrations of ANC, SBC, and dissolved silica, derived primarily from soil mineral weathering reactions. decreased with increasing flow. Furthermore, the ANC was highest at low flow when the percentage of streamflow derived from ground water was maximum. As flow increased, the ANC decreased because the contribution of dilute surface runoff and lateral flow through the shallow acidic soil horizons to total flow increased. Basins having relatively high ground-water contributions to total flow, in general, have large deposits of thick till or stratified drift. A major factor controlling the sensitivity of these streams and lakes to acidification is the relative contribution of ground water to total discharge. ?? 1987 Martinus Nijhoff/Dr W. Junk Publishers.

Biogeochemistry↗