Geology topics

J. R. Deacon

Publications and source records attributed to J. R. Deacon.

6 recordsLinked to original sources

USGS2008

Nitrogen attenuation in the Connecticut River, northeastern USA; a comparison of mass balance and N2 production modeling approaches

Two methods were used to measure in-stream nitrogen loss in the Connecticut River during studies conducted in April and August 2005. A mass balance on nitrogen inputs and output for two study reaches (55 and 66 km), at spring high flow and at summer low flow, was computed on the basis of total nitrogen concentrations and measured river discharges in the Connecticut River and its tributaries. In a 10.3 km subreach of the northern 66 km reach, concentrations of dissolved N2 were also measured during summer low flow and compared to modeled N2 concentrations (based on temperature and atmospheric gas exchange rates) to determine the measured "excess" N2 that indicates denitrification. Mass balance results showed no in-stream nitrogen loss in either reach during April 2005, and no nitrogen loss in the southern 55 km study reach during August 2005. In the northern 66 km reach during August 2005, however, nitrogen output was 18% less than the total nitrogen inputs to the reach. N2 sampling results gave an estimated rate of N2 production that would remove 3.3% of the nitrogen load in the river over the 10.3 km northern sub-reach. The nitrogen losses measured in the northern reach in August 2005 may represent an approximate upper limit for nitrogen attenuation in the Connecticut River because denitrification processes are most active during warm summer temperatures and because the study was performed during the annual low-flow period when total nitrogen loads are small. ?? 2008 Springer Science+Business Media B.V.

Biogeochemistry↗

USGS2003

Nutrient and chlorophyll relations in selected streams of the New England coastal basins in Massachusetts and New Hampshire, June-September 2001

The U.S. Environmental Protection Agency is developing guidance to assist states with defining nutrient criteria for rivers and streams and to better describe nutrient-algal relations. As part of this effort, 13 wadeable stream sites were selected, primarily in eastern Massachusetts, for a nutrient-assessment study during the summer of 2001. The sites represent a range of water-quality impairment conditions (reference, moderately impaired, impaired) based on state regulatory agency assessments and previously assessed nitrogen, phosphorus, and dissolved-oxygen data. In addition, a combination of open- and closed-canopy locations were sampled at six of the sites to investigate the effect of sunlight on algal growth. Samples for nutrients and for chlorophyll I from phytoplankton and periphyton were collected at all stream sites. Total nitrogen (dissolved nitrite + nitrate + total ammonia + organic nitrogen) and total phosphorus (phosphorus in an unfiltered water sample) concentrations were lowest at reference sites and highest at impaired sites. There were statistically significant differences (p < 0.05) among reference, moderately impaired, and impaired sites for total nitrogen and total phosphorus. Chlorophyll a concentrations from phytoplankton were not significantly different among site impairment designations. Concentrations of chlorophyll a from periphyton were highest at nutrient-impaired open-canopy sites. Chlorophyll a concentrations from periphyton samples were positively correlated with total nitrogen and total phosphorus at the open- and closed-canopy sites. Correlations were higher at open-canopy sites (p < 0.05, rho = 0.64 to 0.71) than at closed-canopy sites (p < 0.05, rho = 0.36 to 0.40). Statistically significant differences in the median concentrations of chlorophyll a from periphyton samples were observed between the open- and closed-canopy sites (p < 0.05). Total nitrogen and total phosphorus data from moderately impaired and impaired sites in this study exceeded the preliminary U.S. Environmental Protection Agency nutrient criteria values for the coastal region of New England. In an effort to establish more appropriate nutrient and chlorophyll criteria for streams in the New England coastal region, relations between total nitrogen and total phosphorus to periphyton chlorophyll a in wadeable streams from this study were quantified to present potential techniques for determining nutrient concentrations. Linear regression was used to estimate the total nitrogen and total phosphorus concentrations that corresponded to various chlorophyll a concentrations. On the basis of this relation, a median concentration for moderately enriched streams of 21 milligrams per square meter (mg/m 2 ) of periphyton chlorophyll a from the literature corresponded to estimated concentrations of 1.3 milligrams per liter (mg/L) for total nitrogen and 0.12 mg/L for total phosphorus. The median concentration for periphyton chlorophyll a from the literature is similar to the 50 th -percentile concentration of periphyton chlorophyll a (17 mg/m 2 ) calculated with the data from open-canopy sites in this study. The 25 th -percentile concentration for periphyton chlorophyll a of all open-canopy sites (5.2 mg/m 2 ) and the 75 th -percentile concentration for periphyton chlorophyll a of open-canopy reference sites (16 mg/m 2 ) also were plotted to provide additional estimates and methods for developing total nitrogen and total phosphorus criteria. The 25 th -percentile concentrations of total nitrogen and total phosphorus were calculated based on all sites in this study and were used as another potential criteria estimation. A concentration of 0.64 mg/L for total nitrogen and 0.030 mg/L for total phosphorus were calculated. As another possible method to develop threshold concentrations, the 10 th -percentile concentrations of total nitrogen and total phosphorus were calculated based on all the impaired sites in this study. A concentration threshold of 0.73 mg/L for total nitrogen and 0.036 mg/L for total phosphorus were calculated. Ultimately, a combination of these techniques may be appropriate for water-resources managers to use to set regional nutrient criteria to limit undesirable levels of algal growth in streams.

Massachusetts, New Hampshire↗

USGS2001

Using water, bryophytes, and macroinvertebrates to assess trace element concentrations in the Upper Colorado River Basin

This study examined trace elements concentrations and macroinvertebrate community structure at 32 sites in 22 streams in Colorado. Sites affected by mining activities (mining sites) and sites that were minimally disturbed (nonmining sites) were selected for the assessment. Water and transplanted aquatic bryophyte samples were analyzed for trace elements. Macroinvertebrate samples were collected to assess the effects of trace elements on the aquatic community of the stream. All samples of aquatic bryophytes had detectable concentrations of Cd, Cu, Pb and Zn. Principal components analysis of chemical and physical properties classified sites into three groups. The first group represented sites that were unaffected to minimally affected by mining activities; the second group was characterized by sites with Cd, Pb and Zn predominant in the mineralogy; and the third group was characterized by sites with Cu predominant in the mineralogy. Six macroinvertebrate families were common in the study area. Median values of total abundance, taxa richness and mayfly and stonefly abundance were reduced at mining sites. Abundances of Heptageniidae, Chloroperlidae and Rhyacophila and Baetis sp. also were reduced at sites with elevated trace element concentrations. Tanytarsini chironomids were most abundant at reference and minimally-disturbed sites.

Hydrobiologia↗

USGS1999

Distribution of trace elements in streambed sediment associated with mining activities in the Upper Colorado River Basin, Colorado, USA, 1995-96

Streambed-sediment samples were collected in the Southern Rocky Mountains physiographic province in the Upper Colorado River Basin in Colorado to characterize the occurrence and distribution of trace elements in mined and nonmined areas of the basin. During October 1995 and September 1996, streambed sediment was collected at 37 sites, and the samples were analyzed for trace elements. The ranges in concentrations of As, Cd, Cu, Pb, and Zn at mining sites generally were orders of magnitude higher than the ranges of concentrations at nonmining sites. Sampling sites located in two predominant rock types in mining areas were not significantly different (p > 0.05) for concentrations of As, Cd, Pb, and Zn. Cu was significantly different (p < 0.05) between sites in the two predominant rock types. Concentrations of As, Cd, Cu, Pb, and Zn were not significantly different (p > 0.05) between main-stem sites and tributary sites. Concentrations of As, Cd, Cu, Pb, and Zn exceeded established guidelines for adverse effects on aquatic biota at some sites in the study area. The patterns in concentrations of Cd and Zn, Cd and Pb, and Pb and Zn were highly correlated to one another in this study. Concentrations of trace elements in the <63-??m fraction were higher than in the total particle-size fraction analysis. Comparison of reference sites to sites affected by a mine source indicated that trace- element concentrations initially increased downstream of the source and then gradually decreased in concentration with distance from the source.

Archives of Environmental Contamination and Toxico↗

USGS1998

Water-quality characteristics of the Slate and East rivers, Colorado, during the winter recreational season, December 1996

Periods of population influxes during winter recreation occur simultaneously with periods of extreme low flow in many Rocky Mountain areas. The ability of streams to assimilate additional nutrient loading is reduced by the low-flow conditions. Low-flow water-quality characteristics of the Slate and East Rivers, which drain the Crested Butte area, were investigated in December 1996. Six sites were chosen for evaluation-four on the Slate River and two on the East River-to assess water-quality conditions, including nutrient (nitrogen and phosphorus) concentrations and algal biomass, during a 24-hour period. Discharge in the Slate River ranged from about 18 to 30 cubic feet per second, and discharge in the East River downstream from the mouth of the Slate River was about 80 cubic feet per second. Chemical concentrations in water in the Slate and East Rivers generally were dilute with specific-conductance values of 175 to 300 microsiemens per centimeter and alkalinity values of 40 to 110 milligrams per liter during low-flow conditions. Dissolved oxygen was at or near saturation at all measurements sites. Ammonia nitrogen concentrations increased downstream from Crested Butte and Mount Crested Butte in the Slate River and then returned to background concentrations in the East River. Concentrations of nitrite plus nitrate nitrogen increased downstream from the Crested Butte area, probably associated with the nitrification of the ammonia to nitrate, and concentrations then were diluted in the East River downstream from the confluence of the Slate River. Phosphorus concentrations also increased slightly in the reach downstream from Crested Butte and Mount Crested Butte. Algal biomass values increased downstream from the Crested Butte area, decreased to low values in a subsequent reach, and then returned to higher values downstream. Biomass values were similar to those found in unenriched to moderately enriched streams. The lower biomass and higher phosphorus values occurred in a reach that was covered completely with ice and snow. Algal biomass in this reach was extremely low, probably due to the absence of light. The biomass values upstream and downstream from this reach were moderately high and probably resulted in the lower phosphorus and possibly somewhat lower nitrogen, which suggests that benthic algae may be partially controlling the nutrient levels through assimilation and uptake. When light conditions restrict algal growth and subsequent loading occurs, the concentrations of phosphorus increase slightly. Once the physical limitation (absence of light) is removed, the biomass responds with a corresponding decrease in phosphorus. The nutrient concentrations were low and well below stream standards. Nutrient increases were measured downstream from Crested Butte and Mount Crested Butte, and these increases resulted in an increase of algal biomass. Overall results indicate that, at the present time, the Slate and East Rivers can assimilate winter low-flow nutrient loads.

Colorado↗

USGS1998

Trace elements in streambed sediment and fish liver at selected sites in the Upper Colorado River Basin, Colorado 1995-96

Trace elements were analyzed in streambed-sediment samples collected from 16 sites and in fish-liver samples collected from 14 sites in the Upper Colorado River Basin in Colorado as part of the National Water-Quality Assessment program. Sites sampled represented agricultural, mining, mixed, and urban/recreation land uses and background conditions. The results for 15 trace elements in streambed-sediment and in fish-liver samples are presented in this report. Fourteen of the selected trace elements were detected in streambed-sediment samples collected at all sites. Twelve of the selected trace elements were detected in fish liver at more than 50 percent of the sites. Cadmium, copper, selenium, and zinc were selected for a more detailed analysis. Cadmium, copper, and zinc concentrations in streambed sediment were highest at mining land-use sites in the Southern Rocky Mountains physiographic province. Selenium concentrations in streambed sediment were highest at an agricultural land-use site in the Colorado Plateau physiographic province. The concentration of trace elements in streambed sediment generally increased as particle size decreased. Concentrations of trace elements in fish liver generally did not follow the same relation to land use as concentrations in streambed sediment; however, cadmium concentrations in fish liver were highest at a mining land-use site in the Southern Rocky Mountains physiographic province, and selenium concentrations in fish liver were highest at an agricultural land-use site in the Colorado Plateau physiographic province. Copper and zinc concentrations in fish liver were highest at mixed land-use sites. Comparison of streambed-sediment and fish-liver concentrations to two other similar NAWQA studies in the Rocky Mountain region generally indicated similar patterns in relation to land use for streambed sediment, but not for fish liver. Cadmium, copper, and zinc concentrations in streambed sediment were highest at sites affected by mining in all three study units. Selenium concentrations in streambed sediment did not indicate relations among the three study units when compared to land use. Cadmium in fish liver was highest at sites affected by mining in all three study units. Copper, selenium, and zinc in fish liver did not indicate relations among the three study units when compared to land use.

Colorado↗