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P. J. Phillips

Publications and source records attributed to P. J. Phillips.

18 recordsLinked to original sources
USGS2012

Combined sewer overflows: an environmental source of hormones and wastewater micropollutants

Data were collected at a wastewater treatment plant (WWTP) in Burlington, Vermont, USA, (serving 30,000 people) to assess the relative contribution of CSO (combined sewer overflow) bypass flows and treated wastewater effluent to the load of steroid hormones and other wastewater micropollutants (WMPs) from a WWTP to a lake. Flow-weighted composite samples were collected over a 13 month period at this WWTP from CSO bypass flows or plant influent flows ( n = 28) and treated effluent discharges ( n = 22). Although CSO discharges represent 10% of the total annual water discharge (CSO plus treated plant effluent discharges) from the WWTP, CSO discharges contribute 40&ndash;90% of the annual load for hormones and WMPs with high (>90%) wastewater treatment removal efficiency. By contrast, compounds with low removal efficiencies (<90%) have less than 10% of annual load contributed by CSO discharges. Concentrations of estrogens, androgens, and WMPs generally are 10 times higher in CSO discharges compared to treated wastewater discharges. Compound concentrations in samples of CSO discharges generally decrease with increasing flow because of wastewater dilution by rainfall runoff. By contrast, concentrations of hormones and many WMPs in samples from treated discharges can increase with increasing flow due to decreasing removal efficiency.

Environmental Science & Technology↗
USGS2010

Chlorofluorocarbons (CCl3F and CCl2F2) as dating tools and hydrologic tracers in shallow groundwater of the Delmarva Peninsula, Atlantic Coastal Plain, United States

Concentrations of the Chlorofluorocarbons (CFCs) CFC-11 and CFC-12 were determined in groundwater from coastal plain sediments of the Delmarva Peninsula. CFC-modeled ages were calculated independently for CFC-11 and CFC-12, and agreed to within 2–3 years in the majority of the waters. Recharge temperatures, determined from dissolved nitrogen and argon concentrations, varied from 9±2°C over most of the peninsula to 14±2°C at the southernmost tip of the peninsula in Virginia. The CFC-modeled ages were examined in relation to the known hydrogeologic environment, both on regional scales and in more intensively sampled local scale networks. The CFC-modeled recharge years and measured tritium concentrations were used to reconstruct a tritium input function that was compared to the modeled tritium plus 3 He distribution. Most of the present distribution of tritium in Delmarva groundwater is consistent with low dispersivities. The results of the study strongly support the use of CFCs for dating shallow, aerobic groundwater.

Delaware, Maryland↗
USGS2007

Hydrologic landscapes on the Delmarva Peninsula - Part 2: Estimates of base-flow nitrogen load to Chesapeake Bay

ABSTRACT: The relation between landscape characteristics and water chemistry on the Delmarva Peninsula can be determined through a principal-component analysis of basin characteristics. Two basin types were defined by factor scores: (1) well-drained basins, characterized by combinations of a low percentage of forest cover, a low percentage of poorly drained soil, and elevated channel slope; and (2) poorly drained basins, characterized by a combinations of an elevated percentage of forest cover, an elevated percentage of poorly drained soil, and low channel slopes. Results from base-flow sampling of 29 basins during spring 1991 indicate that water chemistry of the two basin types differ significantly. Concentrations of calcium, magnesium, potassium, alkalinity, chloride, and nitrate are elevated in well-drained basins, and specific conductance is elevated. Concentrations of aluminum, dissolved organic carbon, sodium, and silica are elevated in poorly drained basins whereas specific conductance is low. The chemical patterns found in well-drained basins can be attributed to the application of agricultural chemicals, and those in poorly drained basins can be attributed to ground-water flowpaths. These results indicate that basin types determined by a quantitative analysis of basin characteristics can be related statistically to differences in base-flow chemistry, and that the observed statistical differences can be related to major processes that affect water chemistry.

Journal of the American Water Resources Associatio↗
USGS2007

Temporal changes in surface-water insecticide concentrations after the phaseout of diazinon and chlorpyrifos

The recent (late 2001) federally mandated phaseout of diazinon and chlorpyrifos insecticide use in outdoor urban settings has resulted in a rapid decline in concentrations of these insecticides in urban streams and rivers in the northeastern and midwestern United States. Assessment of temporal insecticide trends at 20 sites showed that significant step decreases in diazinon concentrations occurred at 90% of the sites after the phaseout, with concentrations generally decreasing by over 50% in summer samples. Chlorpyrifos concentrations showed significant step decreases in at least 1 season at 3 of the 4 sites with sufficient data for analysis. The decrease in diazinon concentrations in response to the phaseout resulted in a decline in the frequency of concentrations exceeding the acute invertebrate water-quality benchmark of 0.1 μg/L from 10% of pre-phaseout summer samples to fewer than 1% of post-phaseout summer samples. Although some studies have indicated an increase in concentrations of carbaryl in response to the organophosphorous phaseout, carbaryl concentrations only increased at 1 site after the phaseout. A full assessment of the effect of the phaseout of diazinon and chlorpyrifos on surface water will require data on other insecticides used to replace these compounds.

Environmental Science & Technology↗
USGS2004

Pesticides in surface water runoff in south-eastern New York State, USA: Seasonal and stormflow effects on concentrations

Samples from two streams (Kisco River and the Middle Branch of the Croton River) in the Croton Reservoir system in south-eastern New York State, USA were sampled from May 2000 through to February 2001 in order to document the effect of land use, streamflow and seasonal patterns of application on pesticide concentrations in runoff from developed watersheds. Many of the pesticides detected most commonly in this study are generally used in developed areas, and particularly on turfgrass. Pesticide concentrations were generally higher, and the numbers of compounds were generally larger, in samples from the Kisco River than in samples from the Middle Branch, probably because the Kisco River drainage has a greater population density and is more extensively developed. Four pesticides (2,4-D, 2,4-D-methyl, dicamba and metalaxyl) were detected in at least one sample from the Kisco River at a concentration > 1 ??g litre-1, and no pesticides were detected at concentrations >0.4 ??g litre-1 in Middle Branch samples. No human-health-based water-quality standards were exceeded by samples from either site in this study, but samples from the Kisco River contained four insecticides (carbaryl, chlorpyrifos, diazinon and malathion) and one herbicide (2,4-D) in concentrations that exceeded water quality criteria for the protection of aquatic life. The highest concentrations of most compounds occurred during stormflows in both streams in June, September and December, 2000. The lowest concentrations of most compounds at both sites occurred during baseflows from October 2000 through February 2001, even though the concentrations of many compounds increased substantially at the Kisco River site during stormflows in November and December. Detailed data on the variability of pesticide concentrations during stormflows indicate that there may be two sources of pesticides in the Kisco River watershed: (1) elevated concentrations of pesticides during peak flows that occur early in stormflows likely reflect runoff from paved areas, and (2) elevated concentrations during peak flows that occur later in stormflows from areas with lesser amounts of pavement. Data from the Kisco River indicate that the relation between storm discharge and pesticide concentrations varies among compounds, in part because of variation in seasonal application patterns. These variations in the timing of application result in not all stormflows producing increased concentrations of pesticides. Overall, these results indicate the importance of stormflow sampling throughout the year in assessing pesticide late and transport in urbanized, developed areas.

Conference Paper↗
USGS2000

Pesticides in wells in agricultural and urban areas of the Hudson River basin

Ground-water samples from four monitoring well networks in the Hudson River basin were analyzed for pesticides (detection limits from 0.001 to 0.018 ??g/L). The most frequent detections were in samples from shallow depths beneath agricultural areas. Concentrations of pesticides in samples from all four networks were generally below 0.10 ??g/L, and the concentration of only one (cyanazine) exceeded any maximum contaminant levels or health advisory levels set by the U.S. Environmental Protection Agency. The well networks represented two land-use and two well-depth categories as follows: 1. agricultural shallow wells - two springs and 14 wells finished less than 15 m below land surface in unconfined unconsolidated aquifers beneath agricultural land, 2. agricultural water-supply-wells - 31 wells finished 1.8 to 120 m below land surface in unconsolidated unconfined aquifers and bedrock aquifers beneath agricultural land 3. urban/residential shallow-wells - 17 wells finished less than 16 m below land surface in unconfined unconsolidated aquifers beneath urban or residential land; and 4. urban/residential water-supply-wells - 25 water-supply or observation wells finished 5 to 113 m below land surface in unconfined, unconsolidated aquifers and bedrock aquifers beneath urban or residential land. Pesticides were detected in 69 percent of the samples from the agricultural shallow wells, in 29 percent of the samples from the agricultural water-supply wells, in no samples from the urban/residential shallow wells, and in 16 percent of the samples from the urban/residential water-supply wells. At least half of the samples from the agricultural shallow-well network contained two herbicides (atrazine and metolachlor) and one herbicide metabolite (deethylatrazine); other pesticides detected in samples from this network included metribuzin, cyanazine, EPTC, and pendimethalin. Samples from the agricultural water-supply wells contained two insecticides (diazinon and malathion), two herbicides (atrazine and prometon), and one herbicide metabolite (deethylatrazine). Samples from the urban/residential water-supply well network contained two insecticides (diazinon and malathion), and three herbicides (atrazine, metolachlor, and prometon). Pesticides were detected in samples from depths of less than 2 to more than 70 m. Pesticides were detected in samples with nitrate concentrations ranging from less than the detection limit of 0.05 mg/L to 16 mg/L. These results indicate that pesticides are detected most frequently in shallow ground water beneath agricultural areas, and that pesticides can be detected in wells with a wide range of depths and nitrate concentrations.

Northeastern Geology and Environmental Sciences↗
USGS1999

Metolachlor and its metabolites in tile drain and stream runoff in the canajoharie creek watershed

Water samples collected during April−November 1997 from tile drains beneath cultivated fields in central New York indicate that two metabolites of the herbicide metolachlor metolachlor ESA (ethanesulfonic acid) and OA (oxanilic acid) can persist in agricultural soils for 4 or more years after application and that fine-grained soils favor the transport of metolachlor ESA over metolachlor and metolachlor OA. Concentrations of metolachlor ESA from the tile drains ranged from 3.27 to 23.4 μg/L (200−1800 times higher than those of metolachlor), metolachlor OA concentrations ranged from 1.14 to 13.5 μg/L, and metolachlor concentrations ranged from less than 0.01 to 0.1 μg/L. In the receiving stream, concentrations of metolachlor ESA were always below 0.6 μg/L except during a November storm, when concentrations reached 0.85 μg/L. Concentrations of metolachlor ESA in the stream were 2−45 times higher than those of metolachlor, reflecting the greater relative concentrations of metolachlor in surface water runoff than in tile drain runoff. These results are consistent with findings in other studies that acetanilide herbicide degredates are found in much higher concentrations than parent compounds in both surface water and groundwater.

New York↗
USGS1999

Water-quality assessment of the Delmarva Peninsula, Delaware, Maryland, and Virginia: Results of investigations, 1987-91

A regional ground-water-quality assessment of the Delmarva Peninsula was conducted as a pilot study for the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program. The study focused on the surficial aquifer and used both existing data and new data collected between 1988 and 1991. The new water samples were analyzed for major ions, nutrients, radon, volatile organic compounds, and a suite of herbicides and insecticides commonly used on corn, soybeans, and small grains. Samples also were collected from wells completed in deeper, confined aquifers and from selected streams, and analyzed for most of these constituents. The study employed a multi-scale network design. Regional networks were chosen to provide broad geographic coverage of the study area and to ensure that the major hydrogeologic settings of the surficial aquifer were adequately represented. Both the existing data and the data from samples collected during the study showed that agricultural activities had affected the quality of water in the surficial aquifer over most of the Peninsula.

Delaware, Maryland, Virginia↗
USGS1998

Seasonal and spatial patterns of nitrate and silica concentrations in Canajoharie Creek, New York

The impact of nonpoint-source pollution on surface waters in agricultural watersheds is an emerging environmental issue. As part of the U.S. Geological Survey National Water Quality Assessment program in the Hudson River Basin, Canajoharie Creek was monitored for seasonal and spatial patterns of nutrient chemistry from March 1993 to January 1996. Nitrate and silica concentrations in Canajoharie Creek suggest that seasonal and spatial variations of these nutrients are dominated by biological processes, particularly uptake by phytoplankton. Observed concentration patterns were more typical of those observed in much larger, low-gradient streams. The median nitrate and silica concentrations in Canajoharie Creek were significantly lower from April through November than during winter. Concentrations of both constituents declined downstream from the headwaters during base-flow conditions in June 1995. Groundwater and surface water chemistry data support biological causes for downstream decreases in silica. The strong correlation between nitrate and silica in samples collected along the mainstem suggests that most of the nitrate decrease is due to uptake by diatoms. Downstream patterns of chlorophyll-a in phytoplankton strongly suggest the conversion of in-stream nutrients to algal biomass. Data collected from Canajoharie Creek outlet during the northeast drought of 1995 indicate that silica concentrations in May had possibly declined to a level that adversely affected the diatom community. This decline in the diatom population and subsequent resurgence is inferred from a sharp rise in silica concentrations between May and July and a reversal of this trend from mid-July through October without associated changes in hydrology.

Journal of Environmental Quality↗
USGS1998

Pesticides in the Hudson River Basin, 1994-96

The occurrence, distribution, and temporal patterns of pesticide concentrations were studied in the Hudson River Basin during 1994 - 96. This article presents the results of three separate pesticide studies conducted as part of the U.S. Geological Survey (USGS) National Water Quality Assessment (NAWQA) program. Pesticides were found in all three studies, but rarely at concentrations exceeding any U.S. Environmental Protection Agency drinking-water standards. The highest concentrations were detected during and immediately after the first runoff following pesticide applications in the late spring and early summer. The herbicides atrazine and metolachlor were the most commonly detected pesticides and were present in nearly every sample collected from streams draining agricultural areas; they also were detected in many streams draining areas with other land uses. Herbicides were most often detected, and had the highest concentrations, in samples from streams draining agricultural areas, whereas insecticides such as diazinon were most commonly detected, and had the highest concentrations, in samples from streams draining urban areas.

Northeastern Geology and Environmental Sciences↗
USGS1993

Hydrology and chemistry of groundwater and seasonal ponds in the Atlantic Coastal Plain in Delaware, USA

The hydrochemistry of small seasonal ponds was investigated by studying relations between ground-water and surface water in a forested Coastal Plain drainage basin. Observation of changes in the water table in a series of wells equipped with automatic water-level recorders showed that the relation between water-table configuration and basin topography changes seasonally, and particularly in response to spring recharge. Furthermore, in this study area the water table is not a subdued expression of the land surface topography, as is commonly assumed. During the summer and fall months, a water-table trough underlies sandy ridges separating the seasonal ponds, and maximum water-table altitudes prevail in the sediments beneath the dry pond bottoms. As the ponds fill with water during the winter, maximum water-table altitudes shift to the upland-margin zone adjacent to the seasonal ponds. Increases in pond stage are associated with the development of transient water-table mounds at the upland-margin wells during the spring. The importance of small local-flow systems adjacent to the seasonal ponds also is shown by the similarities in the chemistry of the shallow groundwater in the upland margin and water in the seasonal ponds. The upland margin and surface water samples have low pH (generally less than 5.0), and contain large concentrations of dissolved aluminum (generally more than 100 μg 1 −1 ), and low bicarbonate concentrations (2 mg l 4 or less). In contrast, the parts of the surficial aquifer that do not experience transient mounding have higher pH and larger concentrations of bicarbonate. These results suggest that an understanding of the hydrochemistry of seasonally ponded wetlands requires intensive study of the adjacent shallow groundwater-flow system.

Journal of Hydrology↗
USGS1993

Water-quality assessment of the Delmarva Peninsula, Delaware, Maryland, and Virginia--Effects of agricultural activities on, and distribution of, nitrate and other inorganic constituents in the surficial aquifer

Agricultural applications of inorganic fertilizers and manure have changed the natural chemical com- position of water in the surficial aquifer through- out the Delmarva Peninsula. Nitrate, derived from nitrification of ammonia in inorganic fertilizers and manure, is the dominant anion in agricultural areas. Concentrations of nitrate in 185 water samples collected in agricultural areas ranged from 0.4 to 48 mg/L as nitrogen, with a median concen- tration of 8.2 mg/L as nitrogen. Nitrate concen- trations exceeded the U.S. Environmental Protection Agency's maximum contaminant level for drinking water of 10 mg/L as nitrogen in about 33% of the 185 water samples. Groundwater affected by agricultural activities contains significantly higher concentrations of dissolved constituents than does natural groundwater. Concentrations of calcium and magnesium are higher because of liming of soils, and concentrations of potassium and chloride are higher because of applications of potash, a supple- ment to the nitrogen-based fertilizers. Alkalinity concentrations commonly are decreased because the bicarbonate ion is consumed in buffering reactions with acid that is produced during nitrification. Effects of agricultural activities on groundwater quality are not limited to the near-surface parts of the aquifer underlying farm fields. Elevated concentrations are common in aerobic water at or near the base of the aquifer, 80 to 100 ft below land surface. The median concentration of nitrate in water beneath agricultural areas collected from 24 wells deeper than 80 ft below land surface was 8.5 mg/L as nitrogen, and concentrations in 9 of these water samples exceeded the maximum contaminant level. Regional variations in concentrations of nitrate and other agriculture related constituents in the surficial aquifer in the Delmarva Peninsula depend on a number of factors that include geomorphology, geology, soils, land use, and groundwater-flow patterns. (USGS)

Delaware, Maryland, Virginia↗
USGS1989

Ground-water-quality assessment of the Delmarva Peninsula, Delaware, Maryland, and Virginia; analysis of available water-quality data through 1987

Regional water quality conditions were analyzed on the basis of available data for the Delmarva Peninsula. A summary of 3 Federal, 5 State, and 14 local agencies, as well as various nonprofit organizations and universities, serving as repositories for water quality data is presented. Also included is information describing the range of chemical constituents, the ease of retrieving the data, and general characteristics of the data for use in a regional groundwater quality assessment. Certain characteristics of the available data limit their usefulness for a regional assessment of groundwater. These include a (1) lack of information on quality control; (2) inconsistent sampling; preservation, and analytical techniques used among and within agencies; (3) the clustering of sampling wells around known or suspected areas of contamination, which can impose a bias on water quality assessments; and (4) lack of information on sampling locations, well depths, well construction, and aquifer characteristics. Despite these limitations, the analysis provides a foundation for more detailed regional assessments of water resources on the Delmarva Peninsula and highlights areas where pertinent data are needed. Results of the analysis indicate that data on trace element and organic compound concentrations in groundwater in the Delmarva Peninsula are scarce, whereas data for nitrate, iron, and manganese concentrations are relatively abundant. The data indicate that elevated concentrations of nitrate, iron, and manganese are prevalent in water throughout the surficial aquifer--an aquifer that not only is important in recharging the underlying confined aquifer system, but in supplying drinking water to the majority of Delmarva Peninsula residents. (USGS)

Delaware;Maryl;Virginia↗
USGS1987

Ground-water-quality assessment of the Delmarva Peninsula, Delaware, Maryland, and Virginia; project description

In April 1986, the U.S. Geological Survey began a pilot program to assess the quality of the Nation 's surface water and groundwater resources. This National Water-Quality Assessment (NAWQA) program is designed to acquire and interpret information about a wide range of water quality issues. Three groundwater pilot projects have been started, including the project on the Delmarva Peninsula, which covers eastern Maryland and Virginia and most of Delaware. The objectives of the Delmarva project are to: (1) investigate regional groundwater quality on the Delmarva Peninsula, emphasizing a description of the occurrence of trace elements and manmade organic compounds; (2) relate groundwater quality to land use and geohydrologic conditions; and (3) provide a general description of the location, nature, and possible causes of selected water quality problems prevalent in the study area. The shallow aquifer system and the deeper aquifers used for public water supply will be addressed. The shallow aquifer system in the Delmarva Peninsula consists of permeable unconsolidated sand and gravel. Flow systems are localized and small-scale. Farming is common on the peninsula, and the migration of agricultural chemicals to the groundwater system is a local water quality concern. To assess the water quality of the groundwater resources, a regional survey for a wide range of constituents will be conducted in all of the pilot projects to provide a representative sample of groundwater analyses for a national assessment of groundwater quality. Results of this survey may be used as a baseline to monitor future water quality trends. (Lantz-PTT)

Open-File Report↗