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Green roofs cool cities, clean the air, provide habitat, and manage stormwater. They are compelling tools to teach interconnected human-ecological systems. This study included the design, pilot, and evaluation of a fourth-grade science unit entitled "Raising the Green Roof", exploring these connections. Five classrooms in two Midwestern U.S. public elementary schools participated, and 4th-grade students (n = 73) drew systems models at three time points (212 models) and wrote their ideas. Qualitative content analyses of the models showed that learners were increasingly combining social systems (green roof infrastructure) with ecological systems (water cycle) across the unit. Students also increasingly evidenced specific knowledge as they progressed through the unit. The analysis of student models revealed that most student confusion is related to built environment aspects (e.g., how water moves from building roofs to municipal waterways). Results of the study suggest the potential for teaching socio-hydrologic systems thinking at the fourth-grade level. The findings emphasize the need to enhance built environment education for youth in science units that aspire to connect features of the built environment, such as green roofs, with ecology. The study additionally reinforced the effectiveness of place-based units in elementary education that emphasize science practices. [ABSTRACT FROM AUTHOR]

This study investigated uptake of two organic compounds including hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and exogenous caffeine by tomato (Solanum lycopersicum L.), corn (Zea mays L.), and wheat (Triticum aestivum L.). The plants were grown in a growth chamber under recommended conditions and then were exposed to these compounds for 19 days. The uptake of the compounds was measured by sap concentration factor. The plant samples (stem transpiration stream) and solution in the exposure media were taken and analyzed by high performance liquid chromatography-tandem mass spectrometry. The plant stem samples were analyzed after a freeze-thaw centrifugation process. The average sap concentration factor for the RDX by tomato, wheat, and corn was 0.71, 0.67, and 0.65. The average sap concentration factor for the exogenous caffeine by tomato, wheat, and corn was 0.72, 0.50, and 0.34. These relatively high sap concentration factor values were expected as available predictive models offer high sap concentration factor values for moderately hydrophobic and hydrophilic compounds. The generated sap concentration factor values for the RDX and exogenous caffeine are important for improving the accuracy of previously developed machine learning models predicting the uptake and translocation of emerging contaminants. The uptake of two organic compounds (RDX and exogenous caffeine) was examined in three crop plants (corn, wheat, and tomato). There have not been any uptake studies on exogenous caffeine and also we do not have good data for the uptake of RDX by these three crop plants. The estimated sap concentration factor from these experiments fills the gap in the data for developing predictive models for uptake of emerging contaminants. A novel rapid freeze–thaw/centrifugation extraction method followed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to analyze the samples. [ABSTRACT FROM AUTHOR]

This research introduces a new analytical methodology for measuring chemical activity of nonpolar (semi)volatile organic compounds in different sample matrices using automated solid-phase microextraction (SPME). The chemical activity of an analyte is known to determine its equilibrium concentration in the SPME fiber coating. On this basis, SPME was utilized for the analytical determination of chemical activity, fugacity, and freely dissolved concentration using these steps: (1) a sample is brought into a vial, (2) the SPME fiber is introduced into the headspace and equilibrated with the sample, (3) the SPME fiber is injected into the GC for thermal desorption and analysis, and (4) the method is calibrated by SPME above partitioning standards in methanol. Model substances were BTEX, naphthalene, and alkanes, which were measured in a variety of sample types: liquid polydimethylsiloxane (PDMS), wood, soil, and nonaqueous phase liquid (NAPL). Variable sample types (i.e., matrices) had no influence on sampling kinetics because diffusion through the headspace was rate limiting for the overall sampling process. Sampling time was 30 min, and relative standard deviations were generally below 5% for homogeneous solutions and somewhat higher for soil and NAPL. This type of activity measurement is fast, reliable, almost solvent free, and applicable for mixed-media sampling.

Struvite precipitation has the potential for removing and recovering phosphorus from agricultural wastewater streams, such as concentrated animal feeding operations wastewater. However, impacts of anticipated component-ion molar ratios and potentially interfering ions are unknown as are the compounding pH relationship with respect to all potential complexes. This research experimentally investigates and mathematically models these factors. Emphasis is placed upon the composition of formed deposits and model validation with experimental data. Results show that calcium is a major interfering ion affecting the deposit composition, decreasing struvite purity. X-ray diffraction (XRD) and scanning electron microscopy + energy dispersive spectrometry were used to study the deposit structure and elemental composition. Results revealed that the precipitates formed at a pH of 8.7 have regular crystal shape, and XRD analysis confirmed that the precipitates are high-purity struvite. Higher pH (> 10) leads to the formation of amorphous precipitate and decreases the struvite purity in the deposits. To maximize struvite purity, the ratio of Ca to P should be less than 0.5 and the pH near 8.7. DOI: 10.1061/(ASCE)0733-9372(2005)131:10(1433) CE Database subject headings: Agricultural wastes; Water pollution; Wastewater; Nutrients; Phosphorus; pH; Calcium; Ammonia.

The chlorobenzene dioxygenase from Pseudomonas sp. strain P51 converts substituted aromatic compounds to the S configuration at the carbon atom. The enantiomeric excess was higher than the same reaction catalyzed by toluene dioxygenases. This is of interest to the biotechnology industry because cis-dihydrodiols are building blocks for molecules with multiple chiral centers.

Researcher demonstrate that genetically engineered bacteria that normally colonize the roots of poplar trees can survive in the rhizosphere and degrade trichloroethylene. Trichloroethylene is a common groundwater pollutant at hazardous waste sites. Poplar trees grow quickly and a single five-year-old tree could process 53 gallons of polluted water per day.

Phytoremediation is an emerging technology for degradation of organic chemicals. The potential of phytoremediation in the cleanup of contaminated sites and prevention of non-point-source pollution was examined with the pesticide atrazine in two experimental systems. Uptake was determined in batch experiments with 14C ring-labeled atrazine and hybrid poplar trees grown in two soil types. Mineralization was studied utilizing soil microcosms with the addition of root exudates. Results indicate that poplar cuttings were able to uptake the majority of applied atrazine that was not tightly sorbed to the organic fraction of the soil, with no detectable adverse: effects to the trees. The addition of root exudate to microcosms showed slight stimulation and the addition of ground-up root biomass revealed large stimulation of mineralization to 14C[O.sub.2]. From experimentally acquired data, a mathematical model was developed to obtain kinetic rate constants. This research indicates that vegetative uptake and degradation in the rhizosphere can play a major role in remediation at hazardous waste sites.

Deep-rooted trees planted as a buffer zone can intercept runoff and eroded sediments, thus reducing non-point-source pollution due to agricultural chemicals. In this study, Populus sp. were grown in bioreactors with an agricultural soil (silt-loam) and in a silica-sand media; both were spiked with [sup.14]C uniformly ring-labeled atrazine. The plants took up over 11% of the [.sup.14]C labeled atrazine applied to the silt-loam soil and over 91 % of that applied to the silica sand media, with the majority of the [sup.14]C accumulating as nonphytotoxic metabolites in the leaves. Research suggests that, in addition to nutrient uptake, poplar tree buffer strips may be effective in removing atrazine from agricultural percolation and runoff water.