Full-scale evaluation of mercury control with sorbent injection and COHPAC at Alabama Power E.C. Gaston

The overall objective of this project was to determine the cost and impacts of Hg control using sorbent injection into a Compact Hybrid Particulate Collector (COHPAC) at Alabama Power's Gaston Unit 3. This test is part of a program funded by the U.S. Department of Energy's National Energy Technology Laboratory (NETL) to obtain the necessary information to assess the costs of controlling Hg from coal-fired utility plants that do not have scrubbers for SO2 control. The economics will be developed based on various levels of Hg control. Gaston Unit 3 was chosen for testing because COHPAC represents a cost-effective retrofit option for utilities with existing electrostatic precipitators (ESPs). COHPAC is an EPRI-patented concept that places a high air-to-cloth ratio baghouse downstream of an existing ESP to improve overall particulate collection efficiency. Activated carbons were injected upstream of COHPAC and downstream of the ESP to obtain performance and operational data. Results were very encouraging, with up to 90% removal of Hg for short operating periods using powdered activated carbon (PAC). During the long-term tests, an average Hg removal efficiency of 78% was measured. The PAC injection rate for the long-term tests was chosen to maintain COHPAC cleaning frequency at less than 1.5 pulses/bag/hr.     

Aerially guided leak detection and repair: A pilot field study for evaluating the potential of methane emission detection and cost-effectiveness

Novel aerial methane (CH₄) detection technologies were used in this study to identify anomalously high-emitting oil and gas (O&G) facilities and to guide ground-based “leak detection and repair” (LDAR) teams. This approach has the potential to enable a rapid and effective inspection of O&G facilities under voluntary or regulatory LDAR programs to identify and mitigate anomalously large CH₄ emissions from a disproportionately small number of facilities. This is the first study of which the authors are aware to deploy, evaluate, and compare the CH₄ detection volumes and cost-effectiveness of aerially guided and purely ground-based LDAR techniques. Two aerial methods, the Kairos Aerospace infrared CH₄ column imaging and the Scientific Aviation in situ aircraft CH₄ mole fraction measurements, were tested during a 2-week period in the Fayetteville Shale region contemporaneously with conventional ground-based LDAR. We show that aerially guided LDAR can be at least as cost-effective as ground-based LDAR, but several variable parameters were identified that strongly affect cost-effectiveness and which require field research and improvements beyond this pilot study. These parameters include (i) CH₄ minimum dectectable limit of aerial technologies, (ii) emission rate size distributions of sources, (iii) remote distinction of fixable versus nonfixable CH₄ sources (“leaks” vs. CH₄ emissions occurring by design), and (iv) the fraction of fixable sources to total CH₄ emissions. Suggestions for future study design are provided.

Implications: Mitigation of methane leaks from existing oil and gas operations currently relies on on-site inspections of all applicable facilities at a prescribed frequency. This approach is labor- and cost-intensive, especially because a majority of oil and gas–related methane emissions originate from a disproportionately small number of facilities and components. We show for the first time in real-world conditions how aerial methane measurements can identify anomalously high-emitting facilities to enable a rapid, focused, and directed ground inspection of these facilities. The aerially guided approach can be more cost-effective than current practices, especially when implementing the aircraft deployment improvements discussed here.     

A Validation Study of a Rapid Field-Based Rating System for Discriminating Among Flow Permanence Classes of Headwater Streams in South Carolina

Rapid field-based protocols for classifying flow permanence of headwater streams are needed to inform timely regulatory decisions. Such an existing method was developed for and has been used in North Carolina since 1998. The method uses ordinal scoring of 26 geomorphology, hydrology, and biology attributes of streams. The attribute scores are summed and compared to threshold scores to assign a flow permanence class. Our study objective was to evaluate the method’s ability to classify the flow permanence of forested stream reaches from Piedmont and Southeastern Plains ecoregions in South Carolina. Ephemeral reaches scored significantly lower than intermittent and perennial reaches, but scores from intermittent and perennial reaches did not differ. Scores collected in the dry and wet seasons were strongly correlated, indicating that the method was seasonally stable. Scores had positive nonlinear relationships with the maximum recorded wet duration and the proportion of the record that reaches were wet, but were not related to drying frequency. Scores of the presence of baseflow in the dry season were more important in flow permanence classification than those from the wet season. Other important attributes and parameters in discriminating flow classes were macrobenthos, rooted upland plants, bankfull width, drainage area, and ecoregion. Although the North Carolina method did not consistently differentiate intermittent from perennial reaches, the indicator-based approach is a strong foundation from which to build a protocol for South Carolina. Adding measures like bankfull width and drainage area, weighting by ecoregion, or shifting thresholds may be warranted modifications for South Carolina.     

A pore water study of plutonium in a seasonally anoxic lake

Data are presented here on the distribution of ^239,240Pu in the pore waters of two cores taken from a seasonally anoxic lake. The pore water ^239,240Pu profile exhibits a subsurface activity maximum of 230 ± 30 μBqkg^?1 in the 3–6 cm interval in June, as compared to an activity of 5 ± 3 μBqkg^?1 in the overlying water. The pore water ^239,240Pu profile in June follows the solid phase distribution pattern of ^239,240Pu and also the pore water distributions of Fe and Mn. Under more reducing conditions in August, pore water ^239,240Pu activities drop off to undetectable levels at all depths. This rapid change in the pore water ^239,240Pu activity reflects the dynamic nature of Pu diagenesis in these sediments. Potential diffusional fluxes of ^239,240Pu into the lake's hypolimnion in June are calculated to be on the order of 2·5 μBq cm^?2y^?1. This flux would not be significant in altering the solid phase ^239,240Pu inventory (2·8 × 10⁴μBqcm^?2).     

Female choice for parasite-free male satin bowerbirds and the evolution of bright male plumage

Summary Hamilton and Zuk proposed that bright male plumage may have evolved in males of polygynous species as a result of female preferences for males that are able to demonstrate their resistance to disease. They predicted an inverse correlation between female mating preferences and the level of parasitic infection of males. We found such a correlation between the level of infection by a common ectoparasite (Myrsidea ptilonorhynchi: Menoponidae) and mating success of male satin bowerbirds (Ptilonorhynchus violaceus). In addition, we tested and were able to confirm three other predictions derived from their model: that (1) older males had fewer parasites than their younger counterparts, (2) levels of individual parasitic infection are highly correlated between years, and (3) that individuals resighted in successive years are less parasitized than those that fail to return. These results support the bright male model, but they are also consistent with two other hypotheses that may explain plumage dimorphism based on the level of parasitic infection. The correlated infection model suggests that females choose males with few ectoparasites because of a correlation between the level of ectoparasitic infection and heritable resistance to internal infections. In the parasite avoidance model, females favor parasitefree males because it lowers their own prospects for parasitic infection. Our data did not show the predicted relationship between parasite numbers with plumage quality that is needed to support the bright male hypothesis, nor did it show the inverse correlation between male condition and parasite numbers that is predicted by both the bright male and correlated infection hypotheses. Our results are most consistent with the parasite avoidance hypothesis.     

Evaluation of activated carbon fiber filter for sampling of organochlorine pesticides in environmental water samples

A simple method for quantitative analyses of organic chlorine pesticides (OCPs) in environmental water samples such as rainwater, river water and seawater using activated carbon fiber filters (ACFF) is described. ACFF was used as adsorbent to collect the chemicals in water samples. The collection of OCPs was completed almost for one day by stirring the mixture of the sample and the ACFF chips at room temperature. The adsorbed OCPs on the ACFF could be extracted easily with toluene-ethanol (4:1) mixed solvent. The purified extract by a florisil column chromatograph was followed by the analysis using high-resolution gas chromatograph/high-resolution mass spectrometer. Recoveries of OCPs spiked to actual samples such as rainwater, river water and seawater samples were approximately more than 80%, and the coefficients of variations were within 10%. This method was applied to the actual samples and was confirmed to be applicable for monitoring sub-ng/l level OCPs in environmental water samples.     

Light-Duty Motor Vehicle Exhaust Particulate Matter Measurement in the Denver,Colorado, Area

ABSTRACT

A study of particulate matter (PM) emissions from in-use, light-duty vehicles was conducted during the summer of 1996 and the winter of 1997 in the Denver, CO, region. Vehicles were tested as received on chassis dynamometers on the Federal Test Procedure Urban Dynamometer Driving Schedule (UDDS) and the IM240 driving schedule. Both PM10 and regulated emissions were measured for each phase of the UDDS. For the summer portion of the study, 92 gasoline vehicles, 10 diesel vehicles, and 9 gasoline vehicles with visible smoke emissions were tested once. For the winter, 56 gasoline vehicles, 12 diesel vehicles, and 15 gasoline vehicles with visible smoke were tested twice, once indoors at 60 °F and once outdoors at the prevailing temperature. Vehicle model year ranged from 1966 to 1996. Impactor particle size distributions were obtained on a subset of vehicles. Continuous estimates of the particle number emissions were obtained with an electrical aerosol analyzer. This data set is being provided to the Northern Front Range Air Quality Study program and to the State of Colorado and the U.S. Environmental Protection Agency for use in updating emissions inventories.     

Evidence of immunomodulation in nestling American kestrels (Falco sparverius) exposed to environmentally relevant PBDEs

We investigated whether exposure to environmentally relevant polybrominated diphenyl ethers (PBDEs) causes immunomodulation in captive nestling American kestrels (Falco sparverius). Eggs within each clutch, divided by laying sequence, were injected with safflower oil or penta-BDE congeners-47, -99, -100, and -153 dissolved in safflower oil (18.7 microg sigmaPBDEs/egg) approximating Great Lakes birds. For 29 days, nestlings consumed the same PBDE mixture (15.6+/-0.3 ng/g body weight per day), reaching sigmaPBDE body burden concentrations that were 120x higher in the treatment birds (86.1+/-29.1 ng/g ww) than controls (0.73+/-0.5 ng/g ww). PBDE-exposed birds had a greater PHA response (T-cell-mediated immunity), which was negatively associated with increasing BDE-47 concentrations, but a reduced antibody-mediated response that was positively associated with increasing BDE-183 concentrations. There were also structural changes in the spleen (fewer germinal centers), bursa (reduced apoptosis) and thymus (increased macrophages), and negative associations between the spleen somatic index and sigmaPBDEs, and the bursa somatic index and BDE-47. Immunomodulation from PBDE exposure may be exacerbated in wild birds experiencing greater environmental stresses.