Measuring variability in trophic status in the Lake Waco/Bosque River Watershed

<p>Abstract</p> <p>Background</p> <p>Nutrient management in rivers and streams is difficult due to the spatial and temporal variability of algal growth responses. The objectives of this project were to determine the spatial and seasonal <it>in situ </it>variability of trophic status in the Lake Waco/Bosque River watershed, determine the variability in the lotic ecosystem trophic status index (LETSI) at each site as indicators of the system's nutrient sensitivity, and determine if passive diffusion periphytometers could provide threshold algal responses to nutrient enrichment.</p> <p>Methods</p> <p>We used the passive diffusion periphytometer to measure <it>in-situ </it>nutrient limitation and trophic status at eight sites in five streams in the Lake Waco/Bosque River Watershed in north-central Texas from July 1997 through October 1998. The chlorophyll <it>a </it>production in the periphytometers was used as an indicator of baseline chlorophyll <it>a </it>productivity and of maximum primary productivity (MPP) in response to nutrient enrichment (nitrogen and phosphorus). We evaluated the lotic ecosystem trophic status index (LETSI) using the ratio of baseline primary productivity to MPP, and evaluated the trophic class of each site.</p> <p>Results</p> <p>The rivers and streams in the Lake Waco/Bosque River Watershed exhibited varying degrees of nutrient enrichment over the 18-month sampling period. The North Bosque River at the headwaters (NB-02) located below the Stephenville, Texas wastewater treatment outfall consistently exhibited the highest degree of water quality impact due to nutrient enrichment. Sites at the outlet of the watershed (NB-04 and NB-05) were the next most enriched sites. Trophic class varied for enriched sites over seasons.</p> <p>Conclusion</p> <p>Seasonality played a significant role in the trophic class and sensitivity of each site to nutrients. Managing rivers and streams for nutrients will require methods for measuring <it>in situ </it>responses and sensitivities to nutrient enrichment. Nutrient enrichment periphytometers show significant potential for use in nutrient gradient studies.</p

Effects of Aluminum Toxicity on Growth and the Complement of Polypeptides in the Root Tips of Wheat

Aluminum toxicity is the primary limiting growth factor in acid soils. Wheat . The wheat cultivar "Victory" is Al sensitive at 1 ug/ml Al, while the wheat cultivar "TAM W-101" is tolerant at 2 ug/ml Al. Aniol (4) proposed that a group of proteins present only in Al tolerance plants bind with Al to render it harmless to plant cells. This hypothesis was tested by determining if induction of specific proteins was associated with 2 ug/ml Al treatment in Victory and TAM W-101 root tips. The proteins extracted from each cultivar were quantified and analyzed by SOS-PAGE. The effect of Al on the proteins of wheat root tips was not dramatic. SDS-PAGE did not reveal the presence of any new, major proteins which might be Al-binding proteins. Two-dimensional PAGE analysis of the proteins of Victory cytoplasmic and microsomal fractions was conducted. This highly sensitive protein analytic tool revealed eight m~jor proteins in Al-treated Victory root tips that were not present in the controls, and three proteins that were present in the control and not in the Al-treated root tips.Botan

Systems and methods for wastewater treatment

Disclosed is a system and method for treating wastewater. The system includes a bioreactor which defines a basin for receiving wastewater to be treated; a membrane module in fluid communication with the bioreactor; and a dissolution tank. The tank includes a pressure vessel that contains a portion of the wastewater to be treated and provides a regulated, pressurized gas head space above the wastewater. The tank also includes at least one liquid spray nozzle that permits passage of the wastewater into the gas head space of the pressure vessel and an outlet for discharging the wastewater having a desired gas concentration from the pressure vessel. The system also includes a pumping mechanism for supplying the wastewater to the spray nozzle of the tank such that fluid droplets are formed in the gas head space and the gas contained within the pressurized head space is dissolved into the wastewater

Habitat assessment and ecological restoration design for an unnamed tributary of Stone Dam Creek, Conway, Arkansas

Urbanization can lead to increased sedimentation, erosion, pollution, and runoff into streams. The United States Environmental Protection Agency’s (USEPA) Rapid Bioassessment Protocols (RBPs) are sets of guidelines that can be used to assess a habitat’s sedimentology, hydrology, vegetation, and geomorphology to determine impairment. An unnamed tributary of Stone Dam Creek on the University of Central Arkansas (UCA) campus in Conway, Arkansas runs partially underground and through the urbanized UCA campus watershed. The stream was assessed using the USEPA’s RBPs to determine impairment of the stream, and received a RBP score of 71.2 out of 200 compared to 153.5 in a reference stream. An ecological restoration design was then prepared for a 2-year, 1-hour rainfall event to address areas of impairment. The goal was to increase the RBP score by increasing cross-sectional area of the stream as well as by improving stream morphology where possible. With the proposed design, modeled stream velocity was reduced throughout the stream by an average of 19.6%. It was assessed that as a result of the reduction in velocity and changes to morphology, RPB scores would increase throughout the stream reach

System and method for dissolving gases in fluids and for delivery of dissolved gases

Apparatus and methods are disclosed for facilitating dissolution of one or more gases into a liquid. Preferred gases for use with the apparatus are oxygen, air, and ozone. An apparatus of the present invention includes a dissolution tank that includes a pressure vessel, at least one liquid spray nozzle, and a fluid outlet. The apparatus also includes a gas source, an element for passing fluid into the pressure vessel, and a discharge device connected to the fluid outlet, which discharge device is provided with at least one orifice. Preferred applications include wastewater treatment, treatment of drinking water, fermentation, and bioremediation

System and method for dissolving gases in fluids and for delivery of dissolved gases

Apparatus and methods are disclosed for facilitating dissolution of one or more gases into a liquid. Preferred gases for use with the apparatus are oxygen, air, and ozone. This apparatus comprises a dissolution tank that includes a pressure vessel, at least one liquid spray nozzle, and a fluid outlet. It also comprises a gas source, means for passing fluid into the pressure vessel, and a discharge device connected to the fluid outlet, which discharge device is provided with at least one orifice. Preferred applications include wastewater treatment, treatment of drinking water, fermentation and bioremediation

System and method for dissolving gases in liquids

Apparatus and methods for dissolving a gas into a liquid comprises a saturation tank, a high pressure liquid pump in fluid communication with the tank, and a pressurized gas source in communication with a regulated gas head space of the saturation tank is described. The saturation tank comprises a pressure vessel for containing the liquid and has a regulated gas head space above the liquid. It contains at least one liquid spray nozzle that permits passage of liquid into the pressure vessel, and an outlet for the liquid containing dissolved gas. Upon passing the gas-containing liquid into a second fluid, the gas is released in the form of microbubbles. The microbubbles aid in flocculation of suspended particles and promote dissolution of the gas in the second fluid. Preferred gases for use with the apparatus are oxygen, air, and ozone. Anticipated uses include treatment of rivers, streams, and ponds in natural or industrial settings, as well as smaller scale applications

Modeling the Effects of Low Flow Augmentation by Discharge from a Wastewater Treatment Plant on Dissolved Oxygen Concentration in Leon Creek, San Antonio, Texas.

A GIS-based hydrological/water quality model called Non Point Source Model (NPSM) was used to simulate various physical, chemical and biological processes taking place in the Leon Creek Watershed, near San Antonio, Texas. The model was then used to evaluate base flow augmentation scenarios to remedy dissolved oxygen problems during dry, low-flow periods. The effects were demonstrated by increasing base flow in a stream by discharging recycled water from Leon Creek Wastewater Treatment Plant during a three month low-flow period in 1993, 1994 and 1995 respectively. Five scenarios were evaluated in addition to the control scenario (no flow augmentation). Each of the five scenarios represented an increase in base flow by a factor of 0.25, 0.5, 1, 2 and 4 respectively. The study indicated that increasing base flow in the stream increased the mean daily DO concentration in the stream. The most significant effect was observed when the base flow was increased by a factor of 1 onwards, with no data point falling below the DO criterion of 5 mg/l. From the results of DO modeling developed for this project iv and from the scenario analysis, it can be concluded that a minimum flow augmentation of one times base flow (i.e. doubling the base flow) is required in order to see a significant increase in mean daily DO concentration in Leon Creek and associated tributaries and remedy DO problems during low-flow periods. Since there is uncertainty involved in the modeling process, it is recommended that a higher flow augmentation of two times base flow or four times base flow be implemented in order to reduce uncertainty and significantly improve water quality of Leon Creek

Development of an Urban Watershed Rehabilitation Method Using Stakeholder Feedback to Direct Investigation and Restoration Planning

Includes appendicesThis research was supported by the U.S. EPA Science to Achieve Results (STAR) Program under Grant No. R-827147-01-0 and was a project of Texas A&M University's Institute for Science, Technology and Public Policy in The Bush School of Government and Public Service.surveyU.S. Environmental Protection Agency (Grant No. R-827147-01-0

Science in the Supply Chain: Collaboration Opportunities for Advancing Sustainable Agriculture in the United States

Consumers and corporations are increasingly interested in understanding the sustainability of agricultural supply chains and reducing the environmental impacts of food, fiber, feed, and fuel production. This emerging need to quantify environmental impacts from agricultural production creates an opportunity for collaboration with the scientific community. Without such collaboration, sustainability efforts risk failure by adopting unrealistic goals or misguided approaches. This commentary explores the role of science in Field to Market, a nonprofit organization developing a sustainability program for US commodity crops, and highlights opportunities to address emerging science challenges. We evaluate changes over the past 35 years in key environmental impacts of crop production used to inform land managers as well as companies that are committed to improvements. Achieving improvements will only be possible if three key gaps are addressed regarding available simulation models and data, scale of implementation and uncertainty, and effectiveness of conservation practices. Filling these gaps presents an opportunity for dialogue between scientists, farmers, and private-sector stakeholders to advance scientific knowledge and promote the common objective of sustainable agriculture