D. J. Baumgartner

Effects of salinity on growth and evapotranspiration of Typha domingensis Pers.

Abstract The interactions between salinity, growth and evapotranspiration ( E t ) were investigated for Typha domingensis Pers. in a greenhouse growth experiment and in Cienega de Santa Clara, a coastal desert marsh in the Colorado River delta in Mexico. Although Typha is often found in brackish as well as fresh water marshes, salinity imposed severe constraints to its growth and distribution. In the 68 day greenhouse experiment, growth was maximal at 1.1 ppt. (control solution), half-maximal at 3.5 ppt. and negligible above 6 ppt.; 75% mortality occurred at 15 ppt. E t decreased with salinity in proportion to growth reduction. In the Cienega, T. domingensis was only found in water of 5–8 ppt. or less. When inflow water was 1.0 ppt., Typha E t was estimated to be 1.3 times pan evaporation ( E o ), whereas when inflow water was 3.2 ppt., estimated E t E o was only 0.7. An estimated half of the inflow water to the Cienega exited the vegetated portion of the Cienega unused, owing to the salt tolerance limit of Typha . A practical objective of the study was to predict the effect of brine placement from the Yuma Desalting Plant into the Cienega; it was concluded that the resulting inflow salinity of 7–10 ppt. would result in deterioration of the Typha stands owing to excess salinity.

Spatio-temporal fluctuations in the distribution and abundance of demersal fish and epibenthic crustaceans in Yaquina Bay, Oregon

A total of over 32,000 demersal fish and epibenthic crustaceans belonging to 62 species were caught in 42 biweekly trawls from 10 stations in Yaquina Bay, Oregon, during 1967 and 1968. English sole,Parophrys vetulus, was the most abundant species. Seventeen species (13 fishes and 4 crustaceans) constituted 95% of the catch. Total numerical abundances of both individuals (mainly juvenile fishes) and species were greatest in the lower 12 km of the estuary during summer and early fall, a period of water mass stability and increased water temperature and salinity. This section of the estuary is used by many immature fishes and crustaceans as a “nursery area”. These fishes generally emigrate from the estuary as subadults in the fall around the onset of the rainy season. The fewest species were taken in January 1968 from the central, upper-estuarine, and riverine areas of the bay, this being a time when high rainfall and river discharge result in low salinity and temperature. Crustaceans (shrimp and subadult crabs) were generally most abundant in late winter and early spring throughout the estuary. Changes in diversity indices reflected variations in community structure, the influence of migratory species and juvenile fishes, and seasonal changes in dominance. Year-to-year fluctuations in abundance may be due, in part, to local hydrographic and meteorological conditions along the central Oregon coast.

Improved prediction of bending plumes

Integral plume models harbor a fundamental, often significant error because the standard implementation of control volumes, or elements, is inconsistent with the overall geometry of the problem. The error, called the negative volume anomaly, occurs irregularly, being contingent on there being strong bending and large plume diameter. When present it causes entrainment, i.e., dilution, to be overestimated. It is of practical significance because dilution estimates are used to design and assess diffusers. The anomaly arises when constructed round element faces intersect, as they do when plume diameters are large and plume bending is pronounced, inadvertently generating negative volume and a faulty integration of the governing equations. A modified control volume is proposed to correct the error, and its performance is demonstrated. Its development yields clues to other plume behavior, for example, how plume trajectories may respond to the asymmetrical addition of mass and its distribution in the element.

Effect of Irrigation Water Contaminated with Uranium Mill Tailings on Sudan Grass, Sorghum vulgare var. sudanense, and Fourwing Saltbush, Atriplex canescens

A greenhouse experiment was carried out to estimate the effects of irrigation water quality on chemical uptake and productivity of Sudan grass (Sorghum vulgare var. sudanense) and fourwing saltbush (Atriplex canescens). Water and soil were obtained from an inactive U ore processing site near Tuba City, Arizona. Two observation wells provided the irrigation water. One was located upgradient from the contaminated site, and was located in the center of the plume downgradient from the area contaminated by the milling operations. A 50/50 mix of the two well waters was used as a third treatment. Concentrations of Se and U in aboveground tissues of saltbush were significantly (< 0.05) elevated when irrigated with the undiluted contaminated water, but not to unacceptable levels. In the case of Sudan grass, Mo, Se, U, NO3 -N, and S were significantly (< 0.05) elevated in the contaminated water treatment, and all except NO3 -N were elevated with the diluted contaminated water, but again within acceptable limits. Saltbush productivity was not significantly (< 0.05) affected by the three irrigation treatments. Sudan grass aboveground biomass results suggest that the undiluted contaminated plume water could be used for effective crop production, although productivity was significantly better with the nutrient-amended baseline water and the diluted contaminated water. Root biomass was significantly greater in the baseline water irrigation.

PLANT UPTAKE RESPONSE TO METALS AND NITRATE IN SIMULATED URANIUM MILL TAILINGS CONTAMINATED GROUNDWATER

Carrots, squash, and Sudan grass were irrigated with groundwater amended with manganese, molybdenum, selenium, and uranium stock solutions to simulate a range of concentrations found at ten inactive uranium ore milling sites to determine plant tissue levels after a 90 day growth period in sand in a greenhouse. Sudan grass was also dosed with a series of nitrate concentrations. Except for squash response to uranium, all plantsshowed an increased accumulation of each metal, someto unacceptable levels, with increased metal concentration dose. Squash did not accumulate uranium at any dose tested. Increased nitrate in the irrigation water did not have a major influence on Sudan grass accumulation of any metal.

Effects of Grazing Exclusion and Reseeding on a Former Uranium Mill Site in the Great Basin Desert, Arizona

Germinable seed in the soil seed bank and vegetation were characterized at a former uranium mill site in the Great Basin desert , Arizona , 10 years after a remediation program was conducted to remove surface contamination and revegetate the site . The objective of the study was to evaluate the effectiveness of reseeding as routinely practiced to revegetate such sites . Three different conditions at the site were evaluated: (1) an area that had been bladed to remove topsoil then reseeded with exotic and native species and fenced to exclude livestock (ungrazed - bladed - reseeded) (2)a control area inside the fence that had not been bladed or reseeded (ungrazed), and (3) for further comparison , an area outside the fence that was undisturbed by the milling and remediation efforts but has received normal grazing pressure (grazed). Each condition was represented by three plots , from which soil samples and transect data were collected . The diversity of species and total number of viable seeds in the seed ba...