USGS Science⌕ Search

SEARCH · USGS Science

Results for “Plants”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,243 records · Page 69Linked to original sources
USGS1978

Mallets Creek Marsh, Lake Champlain: A plant-nutrient study

Nitrogen and phosphorus dissolved in the interstitial water of Mallets Creek Marsh sediments supply about 42 percent of the nitrogen and about 9 percent of the phosphorus used by rooted macrophytes within the marsh. These percentages may become larger during middle and late summer, when water inflow to the marsh is reduced and the supply of dissolved nitrogen and phosphorus is diminished. Fluctuations in water-surface level alternately saturate and partially dewater sediments between approximately 98.5 feet and 93.5 feet above mean sea level. Repeated water-level declines to below 98.5 feet through lake-level regulation in spring or early summer could transport interstitial nitrogen and phosphorus from the marshes to Lake Champlain. This would decrease the growth of rooted macrophytes within the marsh and promote eutrophication of the lake.

Vermont↗
USGS1978

Impact of flow regulation and power plant effluents on the flow and temperature regimes of the Chattahoochee River - Atlanta to Whitesburg, Georgia

A calibrated and verified transient flow temperature model was used to evaluate the effects of flow regulation and powerplant loadings on the natural temperature regime of the Chattahoochee River in northeast Georgia. Estimates were made of both instantaneous and average natural temperatures in the river during an eight-day period in August 1976. Differences between the computed average natural temperature and an independent estimate of natural temperature based on observed equilibrium temperatures were less than 0.5°C. The combined thermal effects of flow regulation and powerplant effluents resulted in mean daily river temperatures downstream of the powerplants about equal to or less than computed mean natural temperatures during the period of interest. An independent analysis of historical river and air-temperature data, although considerably less accurate than model computations, provided substantially the same result. The range and rates of change of computed natural diurnal temperature fluctuations were considerably less than those presently observed (1976) in the river. The models also were used to simulate summer river temperatures using estimated year 2000 flow conditions and meteorologic data collected during 1976. Except during periods of peak water-supply demand, differences between computed year 2000 river temperatures and observed present-day temperatures were less than 2°C.

Georgia↗
USGS1983

Report of reprocessing of reflection seismic profile X-5 Waste Isolation Pilot Plant site, Eddy County, New Mexico

Seismic reflection profile X-5 exhibits a 7,700 ft long anomalous zone of poor quality to nonexistent reflections between shotpoints 100 and 170, compared to the high-quality, flat-lying, coherent reflections on either side. Results from drill holes in the area suggest 'layer cake' geology with no detectable abnormalities such as faults present. In an attempt to determine whether the anomalous zone of the seismic profile is an artifact or actually indicates a geologic condition, the data were extensively reprocessed using state-of-the-art processing techniques and the following conclusions were made: 1. The field-recorded data in the anomalous zone are of poor quality due to surface conditions and recording parameters used. 2. Reprocessing shows reflectors throughout the anomalous zone at all levels. However, it cannot prove that the reflectors are continuous throughout the anomalous zone. 3. Significant improvement in data quality may be achieved if the line is reshot using carefully determined recording parameters.

Open-File Report↗