Comparison of four methods for the extraction of lipopolysaccharide from cyanobacteria

Four procedures were compared for the extraction of lipopolysaccharide (LPS) from 10 laboratory strains of cyanobacteria. LPS yields as a percentage of cyanobacterial dry weight ranged from 0.03 to 6.13. The heterotrophic bacterial LPS marker 2-keto-3-deoxyoctonoic (KDO) acid was not detectable in any of the cyanobacterial LPS preparations. All methods yielded LPS that contained biologically- and toxicologically-significant quantities of the cyanotoxin microcystin, when applied to some, but not all, microcystin-producing cyanobacterial strains. Of the four methods used, a procedure including Proteinase K, plus RNase and DNase, performed best overall on the basis of minimum time required, higher percentage yields of LPS, and minimal co-extraction of microcystin.     

Colonization and extinction in dynamic habitats: an occupancy approach for a Great Plains stream fish assemblage

Despite the importance of habitat in determining species distribution and persistence, habitat dynamics are rarely modeled in studies of metapopulations. We used an integrated habitat-occupancy model to simultaneously quantify habitat change, site fidelity, and local colonization and extinction rates for larvae of a suite of Great Plains stream fishes in the Arikaree River, eastern Colorado, USA, across three years. Sites were located along a gradient of flow intermittency and groundwater connectivity. Hydrology varied across years: the first and third being relatively wet and the second dry. Despite hydrologic variation, our results indicated that site suitability was random from one year to the next. Occupancy probabilities were also independent of previous habitat and occupancy state for most species, indicating little site fidelity. Climate and groundwater connectivity were important drivers of local extinction and colonization, but the importance of groundwater differed between periods. Across species, site extinction probabilities were highest during the transition from wet to dry conditions (range: 0.52-0.98), and the effect of groundwater was apparent with higher extinction probabilities for sites not fed by groundwater. Colonization probabilities during this period were relatively low for both previously dry sites (range: 0.02-0.38) and previously wet sites (range: 0.02-0.43). In contrast, no sites dried or remained dry during the transition from dry to wet conditions, yielding lower but still substantial extinction probabilities (range: 0.16-0.63) and higher colonization probabilities (range: 0.06-0.86), with little difference among sites with and without groundwater. This approach of jointly modeling both habitat change and species occupancy will likely be useful to incorporate effects of dynamic habitat on metapopulation processes and to better inform appropriate conservation actions.     

Fate of selenium in biofortification of wheat on calcareous soil: an isotopic study

Selenium (Se) biofortification of staple cereal crops can improve the Se nutritional status of populations. A field trial employing an enriched stable isotope of Se (⁷⁷Se) was undertaken over three consecutive cropping seasons in a coarse-textured, calcareous soil in Gilgit-Baltistan, Pakistan. The objectives were to (1) assess the feasibility and efficiency of Se biofortification, (2) determine the fate of residual Se, and (3) assess the consequences for dietary Se intake. Isotopically enriched ⁷⁷Se (⁷⁷Se_Fert) was applied, either as selenate or as selenite, at three levels (0, 10, and 20 g ha^?1) to a wheat crop. Residual ⁷⁷Se_Fert availability was assessed in subsequent crops of maize and wheat without further ⁷⁷Se_Fert addition. Loss of ⁷⁷Se_Fert was c.35% by the first (wheat) harvest, for both selenium species, attributable to the practice of flood irrigation and low adsorption capacity of the soil. No ⁷⁷Se_Fert was detectable in subsequent maize or wheat crops. The remaining ⁷⁷Se_Fert in soil was almost entirely organically bound and diminished with time following a reversible (pseudo-)first-order trend. Thus, repeat applications of Se would be required to adequately biofortify grain each year. In contrast to native soil Se, there was no transfer of ⁷⁷Se_Fert to a recalcitrant form. Grain from control plots would provide only 0.5 µg person^?1 day^?1 of Se. By contrast, a single application of 20 g ha^?1 Se^VI could provide c. 47 µg person^?1 day^?1 Se in wheat, sufficient to avoid deficiency when combined with dietary Se intake from other sources (c. 25 µg day^?1).

     

An integrated decision-support process for adaptation planning: climate change as impetus for scenario planning in an agricultural region of Canada

The amount of information required to adapt to climate change is vast: downscaled climate projections, information on environmental impact, sectoral performance, external drivers, regional strategies, policies and practices. It can be argued that most of this information is accessible at the community/regional level, and thus, the important challenges to adaptation are not information gaps, but constraints created by fragmented planning decisions and a sector-by-sector basis for financial and human resource allocations. To strategically address this through adaptation planning, we developed and tested a place-based decision-making framework that creates an integrated platform for considering regional and global sectoral drivers in Eastern Ontario, Canada. Using available socioeconomic and biophysical information from regional authorities, alternative future scenarios were used to describe the range of socioeconomic futures and their vulnerabilities to climate change. We found that: (1) integration of diverse sets of available data (rather than narrowly focused sectoral assessments) helped identify shared common objectives (maximizing the long-term environmental, economic, social well-being within the region), (2) a high degree of congruence existed as the key drivers of change, irrespective of sector, (3) exploring the future scenarios highlighted shared regional priorities and helped identify adaptation priorities requiring more integrated regional planning.     

An Open Source GIS‐Based Decision Support System for Watershed Evaluation of Best Management Practices

Economic costs, water quantity/quality benefits, and cost effectiveness of agricultural best management practices (BMPs) at a watershed scale are increasingly examined using integrated economic‐hydrologic models. However, these models are typically complex and not user‐friendly for examining the effects of various BMP scenarios. In this study, an open source geographic information system (GIS)‐based decision support system (DSS), named the watershed evaluation of BMPs (WEBs), was developed for creating BMP scenarios and simulating economic costs and water quantity/quality benefits at farm field, subbasin, and watershed scales. This DSS or WEBs interface integrated a farm economic model, the Soil and Water Assessment Tool (SWAT), and an optimization model within Whitebox Geospatial Analysis Tools (GAT), an open source GIS software. The DSS was applied to the 14.3‐km² Gully Creek watershed, a coastal watershed in southern Ontario, Canada that drains directly into Lake Huron. BMPs that were evaluated included conservation tillage, nutrient management, cover crop, and water and sediment control basins. In addition to assessing economic costs, water quantity/quality benefits, and cost effectiveness of BMPs, the DSS can be also used to examine prioritized BMP types/locations and corresponding economic and water quantity/quality tradeoffs in the study watershed based on environmental targets or budget constraints. Further developments of the DSS including interface transfer to other watersheds are also discussed. Editor's note : This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.     

The Stream and Its Altered Valley: Integrating Landscape Ecology into Environmental Assessments of Agro-Ecosystems

Little is known about the importance of landscape and land cover to the implementation and performance of agricultural conservation projects designed to improve stream quality. In our study, we addressed the potential importance of landscape and land cover to conservation projects by measuring variation across 191 μ-basins (100–2400 ha) and integrating the observed variation into a study design aimed at determining the effectiveness of conservation projects. Our findings indicate that there are strong gradients across which landscape and land cover attributes vary. Land cover varied along a gradient of agricultural intensity, basin morphometry across gradients of stream closure and basin size, basin substrate was described by variation in drumlin formation, glacial landform type, and soil drainage, while agricultural conservation projects varied according to the level of project implementation. Correlation of these gradients found several associations between landscape and land cover, indicating that agricultural intensity was being constrained predominantly by drumlin formation and glacial landform type. Landscape and land cover did not appear to be determining factors in the implementation of conservation projects by land owners. Based on these findings we chose 32 μ-basins which represented the variability along each of the defined gradients for further study. We conclude that landscape scale variables demonstrate important variation and covariation that can and should be integrated into study designs for the assessment of streams and human activities affecting streams.     

Analyzing the Effects of Groundwater Pumping on an Urban Stream‐Aquifer System

When the cone of influence of a pumping well reaches a nearby river, the resulting hydraulic gradient can induce enhanced seepage of streamflow into the aquifer. The rate of seepage is often modeled using analytical solutions that are simple to apply but may not reproduce field data due to mathematical assumptions not being met in the field. Furthermore, the appropriateness of such models has not been investigated in detail due to difficulty in measuring streamflow loss in the field. In this study, a field experiment was conducted on a reach of the South Platte River near Denver, Colorado to estimate pumping‐induced streamflow loss. A network of stream gauges, monitoring wells, and in situ measurements was used to observe streamflow rates, groundwater levels, and temperature to assess if pumping wells have a significant impact on streamflow, and to compare observed streamflow depletion against analytical solutions. Data collected suggest that pumping wells have a noticeable impact on streamflow. The analytical solutions proved accurate if streamflow was low and constant but performed poorly if streamflow was high and variable. Therefore, for this reach, the use of analytical solutions to predict streamflow may only be appropriate under low‐flow, constant‐flow conditions. Methods and results can be used to guide other streamflow depletion studies and to inform cases of pumping‐induced streamflow depletion, particularly in regard to water rights.     

In-field radon measurement in water: a novel approach

This paper presents a novel approach of measuring radon in-water in the field by inserting a MEDUSA gamma-ray detector into a 210 L or 1000 L container. The experimental measurements include investigating the effect of ambient background gamma-rays on in-field radon measurement, calibrating the detector efficiency using several amounts of KCl salt dissolved in tap water, and measuring radon in borehole water. The results showed that there is fairly good agreement between the field and laboratory measurements of radon in water, based on measurements with Marinelli beakers on a HPGe detector. The MDA of the method is 0.5 Bq L⁻¹ radon in-water.     

Treatment of Halogenated Organic Vent Streams for the Reduction of Air Emissions

Abstract

This work presents a three-stage treatment system to process halogenated organic vent streams for compliance with the Hazardous Organic NESHAP (HON) Rule. The three stages are incineration, energy recovery, and wet scrubbing. In particular, this work concentrates on the design of the scrubber, which the HON Rule states must remove at least 99% of any halogens or hydrogen halides generated during the combustion step. Computerized process simulation was found to be ineffective in designing a scrubber for this application, so laboratory data on the partial pressure of the hydrogen halide species over aqueous solutions was employed. The number of overall gas transfer units required for 99% removal was found to be slightly less than 5, and the overall gas transfer unit height was found to be approximately 0.5 m.     

Field Validation of Sound Mitigation Models and Air Pollutant Emission Testing in Support of Missile Motor Disposal Activities

Abstract

The U.S. Department of Defense approved activities conducted at the Utah Test and Training Range (UTTR) include both operational readiness test firing of intercontinental ballistic missile motors as well as the destruction of obsolete or otherwise unusable intercontinental ballistic missile motors through open burn/open detonation (OB/ OD). Within the Utah Division of Air Quality, these activities have been identified as having the potential to generate unacceptable noise levels, as well as significant amounts of hazardous air pollutants. Hill Air Force Base, UT, has completed a series of field tests at the UTTR in which sound-monitoring surveillance of OB/OD activities was conducted to validate the Sound Intensity Prediction System (SIPS) model. Using results generated by the SIPS model to support the decision to detonate, the UTTR successfully disposed of missile motors having an aggregate net explosive weight (NEW) of 56,500 lbs without generating adverse noise levels within populated areas. These results suggest that, under appropriate conditions, missile motors of even larger NEW may be detonated without exceeding regulatory noise limits. In conjunction with collecting noise monitoring data, air quality data was collected to support the development of air emission factors for both static missile motor firings and OB/OD activities. Through the installation of 15 ground-based air samplers, the generation of combustion fixed gases, hazardous air pollutants, and chlorides were monitored during the 56,500-lb NEW detonation event. Comparison of field measurements to predictions generated from the U.S. Navy’s energetic combustion pollutant formation model, POLU4WN, indicated that, as the detonation fireball expanded from ground zero, organic compounds as well as carbon monoxide continued to oxidize as the hot gases reacted with ambient air. Hazardous air pollutant analysis of air samplers confirmed the presence of chloromethane, benzene, toluene, 1,2-propadiene, and 2-methyl-1-propene, whereas the absence of hydrogen chloride gas suggested that free chlorine is not generated during the combustion process.