Publications

No abstract available at this time

No abstract available at this time

Rainfall, streamflow, sediment, and turbidity data are being collected as part of a study to evaluate the effects of highway construction on sediment discharge. The study is also designed to determine the effectiveness of different erosion-control measures in reducing sediment discharges. The study area, near Enola, Pa., consists of five adjacent drainage basins, four of which will be crossed by I

Rainfall, streamflow, stream chemical, and sediment discharge data were collected from Bixler Run near Loysville, Pa., during the period from February 1954 to September 1969 as part of a project to evaluate sediment discharge from an agricultural area in which soil-conservation techniques were being adopted at a moderate rate. The study was conducted by the U.S. Geological Survey in cooperation wi

Limnological data on major streams in Chester County, Pennsylvania are tabulated to provide a base line as to the present stream conditions. As land-use patterns change and further urbanization takes place, it is anticipated that these data will serve as a basis for comparison of conditions in the future. The 13 basins encompass a total drainage area of 1,812 km2 (697 mi2) of the 1,976 km2 (760 mi

Lead concentration in blood and erythrocyte delta-aminolevulinic acid dehydratase (ALAD) activity was measured in mallard ducks dosed with one all-lead shot or one lead-iron combination shot. For 2 weeks after dosage, lead in blood of ducks given an all-lead shot was fourfold higher than in those dosed with lead-iron shot. At 3 and 4 weeks, the differences in lead residues were directly proportion

For 2 consecutive years mallard (Anas platyrhynchos) hens were fed a control diet or a diet that contained 0.5 or 3 ppm mercury as methylmercury (about 0.1 and 0.6 ppm mercury on the basis of a natural succulent diet). During the fifth egg-collection period, levels of mercury in eggs of hens fed 0.5 and 3 ppm mercury averaged 0.79 and 5.46 ppm, respectively; on a dry-weight basis, the concentratio

Mallard ducks (Anas platyrhynchos) whose parents were fed a diet containing 0.5 ppm mercury (equal to about 0.1 ppm mercury in a natural diet) also were fed a diet containing 0.5 ppm mercury beginning at 9 days of age and continuing through their reproductive season. Mercury in the eggs of treated hens averaged 0.86 ppm. Hens fed 0.5 ppm mercury made less efficient use of feed and laid a greater p

Mallard drakes (Anas platyrhynchos) fed 1, 5, or 25 ppm lead nitrate were bled and sacrificed at 3‐wk intervals. No mortality occurred, and the pathologic lesions usually associated with lead poisoning were not found. Changes in hematocrit and hemoglobin concentration did not occur. After 3 wk ducks fed 25 ppm lead exhibited a 40% inhibition of blood δ‐aminolevulinic acid dehydratase activity that

No abstract available.

Optimal exploitation strategies were studied for an animal population in a Markovian (stochastic, serially correlated) environment. This is a general case and encompasses a number of important special cases as simplifications. Extensive empirical data on the Mallard (Anas platyrhynchos) were used as an example of general theory. The number of small ponds on the central breeding grounds was used as

In the May 1973 issue of EOS, I criticized tendencies in earth science periodicals to discourage referee anonymity. I stressed that exposing referees to unnecessary personal and subjective influences tended to degrade standards of quality and promoted cliques, fragmentation, superspecialization, and proliferation of scientific literature. Generally speaking, division of opinion on this question, b