Saltcedar control and water salvage on the Pecos river, Texas, 1999-2003

A large scale ecosystem restoration program was initiated in 1997 on the Pecos River in Western Texas. Saltcedar (Tamarix spp.), a non-native invasive tree, had created a near monoculture along the banks of the river by replacing most native vegetation. Local irrigation districts, private landowners, federal and state agencies, and private industry worked together to formulate and implement a restoration plan, with a goal of reducing the effects of saltcedar and restoring the native ecosystem of the river. An initial management phase utilizing state-of-the-art aerial application of herbicide began in 1999 and continued through 2003. Initial mortality of saltcedar averaged about 85-90%. Monitoring efforts were initiated at the onset of the project to include evaluating the effects of saltcedar control on salinity of the river water, efficiency of water delivery down the river as an irrigation water source, and estimates of water salvage. To date, no effect on salinity can be measured and irrigation delivery was suspended in 2002-2003 due to drought conditions. Water salvage estimates show a significant reduction in system water loss after saltcedar treatment. However, a flow increase in the river is not yet evident. Monitoring efforts will continue in subsequent years.     

Assessment of a turfgrass sod best management practice on water quality in a suburban watershed

The disposal of manure on agricultural land has caused water quality concerns in many rural watersheds, sometimes requiring state environmental agencies to conduct total maximum daily load (TMDL) assessments of stream nutrients, such as nitrogen (N) and phosphorus (P). A best management practice (BMP) has been developed in response to a TMDL that mandates a 50% reduction of annual P load to the North Bosque River (NBR) in central Texas. This BMP exports composted dairy manure P through turfgrass sod from the NBR watershed to urban watersheds. The manure-grown sod releases P slowly and would not require additional P fertilizer for up to 20 years in the receiving watershed. This would eliminate P application to the sod and improve the water quality of urban streams. The soil and water assessment tool (SWAT) was used to model a typical suburban watershed that would receive the sod grown with composted dairy manure to assess water quality changes due to this BMP. The SWAT model was calibrated to simulate historical flow and estimated sediment and nutrient loading to Mary's Creek near Fort Worth, Texas. The total P stream loading to Mary's Creek was lower when manure-grown sod was transplanted instead of sod grown with inorganic fertilizers. Flow, sediment and total N yield were the same for both cases at the watershed outlet. The SWAT simulations indicated that the turfgrass BMP can be used effectively to import manure P into an urban watershed and reduce in-stream P levels when compared to sod grown with inorganic fertilizers.     

Effects of development on runoff and pollutant export.

Runoff from two similar drainage areas in the Piedmont physiographic region of North Carolina was monitored simultaneously for 5.6 years. One of the drainage areas was developed as part of a large residential subdivision, while the other remained in woods and agricultural fields. Runoff volume was 68% greater for the developed compared with the undeveloped area, and baseflow as a percentage of overall discharge was approximately 0% compared with 25% for the undeveloped area. Overall annual export of sediment was 95% greater for the developed area, while export of nitrogen and phosphorus forms was 66 to 88% greater for the developed area. These results document the significant increases in runoff, sediment, and nutrient export associated with residential development.     

Use of Synthetic Aperture Radar for Selecting Alaskan Lakes for Winter Water Use1

Abstract: Water resources are limited in many areas of the North Slope, Alaska, particularly during winter. Water is used by the oil industry for ice road construction and maintenance, drilling and facility operations, and potable water supplies. The coastal plain between Teshekpuk Lake, in the National Petroleum Reserve‐Alaska (NPR‐A) and the Colville River has numerous shallow lakes, but further south in the northern foothills of the Brooks Range, and east to the Canning River, lakes are fewer. While many oil and gas lease sales have been conducted, or are proposed, access to the leases may be limited because of the lack of available water for ice road construction. Ice roads are the main means by which exploration is conducted in the Arctic, putting a stress on freshwater bodies that do not freeze to the lakebed in winter. Lakes that do not freeze to the lakebed also serve as overwintering habitat for fish. The purpose of this paper is to report on the potential distribution of water bodies that may provide overwinter water in selected areas from Teshekpuk Lake to the Canning River. The project used synthetic aperture radar (SAR) imagery to search for the presence of water in lakes in March 2006. In the Kuparuk and Canning SAR images, 52 and 61% of lakes were frozen to their beds by March 2006, accounting for 49 and 57% of the lake area in these study regions. Conversely, only 2% of the lakes in the Teshekpuk region were frozen to the bottom by March 2006. Unfrozen water was more available because of deeper and more numerous lakes in the Teshekpuk Lake region (west) than in the Canning River area (east). While only specific SAR tiles were analyzed herein, the method will be a useful tool for land managers who seek to evaluate the potential for ice road construction across the Arctic.     

A biosocial model of entrepreneurship: the combined effects of nurture and nature

Why do people get involved in the creation of new ventures? Prior research suggests entrepreneurial behavior has multiple causes. Nurture explanations; often couched in terms of sociological theories like social learning have been popular. Aspects of nascent entrepreneurs' social contexts, notably their family business background, have been associated with new venture creation. But nature also appears to play a role. Other research has linked heritable biological factors, including testosterone, with the career choice to launch a new venture. This study presents theory and evidence linking the combination of both sociological and biological factors with new venture creation: a biosocial model of entrepreneurship. Empirical results indicate new venture creation is more likely among those individuals having a higher testosterone level in combination with a family business background. Copyright © 2007 John Wiley & Sons, Ltd.     

Guidance for the performance evaluation of three-dimensional air quality modeling systems for particulate matter and visibility

Guidance for the performance evaluation of three-dimensional air quality modeling systems for particulate matter and visibility is presented. Four levels are considered: operational, diagnostic, mechanistic, and probabilistic evaluations. First, a comprehensive model evaluation should be conducted in at least two distinct geographical locations and for several meteorological episodes. Next, streamlined evaluations can be conducted for other similar applications if the comprehensive evaluation is deemed satisfactory. In all cases, the operational evaluation alone is insufficient, and some diagnostic evaluation must always be carried out. Recommendations are provided for designing field measurement programs that can provide the data needed for such model performance evaluations.     

Sensitivity of marine fishes to toxins from the red-tide dinoflagellate Gonyaulax excavata and implications for fish kills

Marine fishes (Atlantic herring, American pollock, winter flounder, Atlantic salmon, and cod) were dosed orally and intraperitoneally (i.p.) with paralytic shellfish toxins extracted from Bay of Fundy Gonyaulax excavata (tamarensis) cells. The toxins are lethal to these fishes in low oral doses, and in extremely low i.p. doses. Symptoms are the same among these fishes, both for oral and i.p. administrations, including loss of equilibrium within 5 to 15 min, followed by immobilization and shallow, arrhythmic breathing. Death generally occurs within 20 to 60 min of toxin administration. Dose responses are also similar among these fishes. Oral LD50 values are 400 to 750 g saxitoxin (STX) equivalent kg^-1 body weight. Intraperitoneal LD50 values are 4 to 12 g STX equivalent kg^-1. Toxins are undetectable in fish muscle tissue following lethal oral doses. The similarity of symptoms and dose responses suggest that fish as a group are sensitive to G. excavata toxins. Results, in combination with reports implicating these toxins in herring, sand lance, and menhaden kills, show the plausibility that the nearly worldwide blooms and red tides of G. excavata and its relatives may cause kills of a variety of fishes.     

Maternal uniparental heterodisomy for chromosome 2: detection through ‘atypical’ maternal AFP/hCG levels,with an update on a previous case

We report a case of maternal uniparental disomy 2, detected through routine screening of placental karyotypes following the finding of ‘atypical’ AFP/hCG levels in the second trimester, with intrauterine growth retardation (IUGR) but otherwise normal outcome at term. Although the child remained small, subsequent early physical and mental development has also been normal. Additionally, we report long-term follow-up of an earlier case, again with relatively normal physical and mental development. The significance of atypical AFP/hCG results and the predictive value of prenatal testing for UPD2 in trisomy 2 confined placental mosaicism (CPM) cases are discussed. Copyright © 2001 John Wiley & Sons, Ltd.     

Activation energy for skeletal aragonite deposited by the hermatypic coral Platygyra spp.

Average radial growth rates of the hemispherical aragonite colonies deposited by the Indo-Pacific scleractinian reef coral Platygyra spp. were determined by measuring the thickness of density variations in the skeleton that are revealed by X-radiography. Ninety-one specimens from 21 localities were examined, but only 54 of these exhibited well-defined growth-banding. The apparent temperature dependence of growth rate is linear over the range 23.9° to 29.3°C, averaging 5.4±0.94 mm/year at 24°C, 8.0±0.42 mm/year at 27°C, and 9.7 ±0.58 mm/year at 29°C (90% confidence limits). Expression of the influence of temperature on growth rate in terms of the Arrhenius equation yields an activation energy of 20,680 cal/mole, which is comparable to values for typical biological reactions, but is only half that reported for skeletogenesis in another reef coral, Pocillopora damicornis, on the basis of controlled incubation studies involving ⁴⁵Ca uptake.