Randolph B. See

Selenium source identification and biogeochemical processes controlling selenium in surface water and biota, Kendrick Reclamation Project, Wyoming, U.S.A.

Abstract The major tributaries draining the Kendrick Reclamation Project (KRP) account for an average of 52% of the total Se load measured in the North Platte River downstream from Casper, Wyoming. The Casper Creek drainage basin contributed the largest Se load of the five tributary sites to the North Platte River. The 4-d average Se concentration in water samples from one site in the part of the North Platte River that receives irrigation return flows exceeded the 5 μg/l U.S. Environmental Protection Agencys aquatic life criterion five time during a 50-d monitoring period in 1989. In agreement with the water-quality data, muscle and liver tissue rom rainbow trout collected from the same part of the North Platte River had Se concentrations exceeding levels known to cause reproductive failure and chronic Se poisoning. On the basis of Se: Cl, 18O/16O and D/H ratios in water from Goose and Rasmus Lee Lakes (closed-basin systems), the large Se concentrations in those lakes were derived by natural evaporation of irrigation water without leaching of soluble forms of Se from soil or rocks. Water samples from Thirtythree Mile Reservoir and Illco Pond (flow-through systems) showed considerable enrichment in Se over evaporative concentration, presumably due to leaching and desorption of Se from soil and rock. The Se: Cl ratios of irrigation drain water collected from the KRP indicate that leaching and desorption of soluble forms of Se from soils and rocks are the dominant processes in drain water. Results of a Wilcoxon matched-pairs test for 43 paired drain-water samples collected during June and August 1988, indicated there is a statistically larger concentration of Se (0.01 significance level) during the June sampling period. The larger concentrations of Se and other chemical constitutents during the early part of the irrigation season probably were due to dissolution of seleniferous salts that have accumulated in soils within the KRP since the last irrigation season. The large Se concentrations in water samples from wetland sites in the KRP were reflected in the aquatic-bird food chain. Most waterfowl and shorebirds nesting at the KRP showed Se concentrations in livers and eggs greater than levels suspected of causing adverse reproductive effects.

A quality-assurance assessment for constituents reported by the national atmospheric deposition program and the national trends network

Abstract A continuing quality-assurance program has been operated by the U.S. Geological Survey to evaluate any bias introduced by routine handling, shipping, and laboratory analyses of wet-deposition samples collected in the National Atmospheric Deposition Program (NADP) and National Trends Network (NTN). Blind-audit samples having a variety of constituent concentrations and values were selected. Only blind-audit samples with constituent concentrations and values less than the 95th-percentile concentration for natural wet-deposition samples were included in the analysis. Of the major ions, there was a significant increase of Ca 2+ , Mg 2+ , Na 2+ , K + , SO 4 2− and Cl −1 in samples handled according to standard protocols and shipped in NADP/NTN sample-collection buckets. For 1979–1987, graphs of smoothed data showing the estimated contamination in blind-audit samples indicate a decrease in the median concentration and ranges of Ca 2+ , Mg 2+ and SO 4 2− contamination of blind-audit samples shipped in sample-collection buckets. Part of the contamination detected in blind-audit samples can be attributed to contact with the sample-collection bucket and lid; however, additional sources also seem to contaminate the blind-audit sample. Apparent decreases in the magnitude and range of sample contamination may be caused by differences in sample-collection bucket- and lid-washing procedures by the NADP/NTN Central Analytical Laboratory. Although the degree of bias is minimal for most constituents, summaries of the NADP/NTN data base may contain overestimates of Ca 2+ , Mg 2+ , Na − , K + and SO 4 2− and Cl − concentrations, and underestimates of H + concentrations.

Description and testing of three moisture sensors for measuring surface wetness on carbonate building stones

Three moisture sensors were tested as a means for determining the surface wetness on carbonate building stones exposed to conditions that produce deposition of moisture. A relative‐humidity probe, a gypsum‐coated circuit grid, and a limestone‐block resistor were tested as sensors for determining surface wetness. Sensors were tested under laboratory conditions of constant relative humidity and temperature and also under on‐site conditions of variable relative humidity and temperature for eight weeks at Newcomb, NY. Laboratory tests indicated that relative humidity alone did not cause sensors to become saturated with water. However, the rates of drying indicated by the sensors after an initial saturation were inversely related to the relative humidity. On‐site testing of the relative‐humidity probe and the gypsum‐coated ciruit grid indicated that they respond to a diurnal wetting and drying cycle; the limestone‐block resistor responded only to rainfall.