Technical Bulletins

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Technical Bulletin No. 1050: Compilation of Air Toxics Emissions Data for Pulp and Paper Sources - Publication Accompanying the 2018 Air Toxics Emissions Database

PDF , Source: Technical Bulletins Published: 09/2018 View Abstract

Abstract: This technical publication accompanying the 2018 NCASI Air Toxics Emissions Database presents the results of application of updated data handling and statistical procedures to the NCASI Air Toxics Database. Using a combination of database and statistical software, NCASI staff developed and implemented procedures to automatically perform data cleaning, outlier identification, and the calculation of summary statistics. Previously used graphical methods for confirming non-representative data (statistical outliers) have been replaced by numerical calculations. Methods for handling emissions data below detection limits have also been refined; the SDln method used in previous emission factor compilations to handle highly censored datasets (with high fractions of nondetects) has been replaced by a simple arithmetic average of the detected value with the non-detect values treated at half the detection limit. The previously identified issues with application of the Kaplan-Meier (K-M) technique to the calculation of medians have also been addressed. Finally, a number of transcription and/or calculation errors have been corrected. Overall, the revised data handling and statistical procedures have resulted in a more robust and defensible set of air toxics emission factors. This report is designed to accompany the Air Toxics Master Summary Table, a Microsoft Excel spreadsheet widely used for regulatory reporting and other non-regulatory applications. Additional information about the underlying test data used to calculate the emissions estimates in this document may be found in Technical Bulletin No. 973, as well as Detail Sheets A1-B10. Electronic versions of the Air Toxics Master Summary Table and the Detail Sheets are available on the NCASI website.

Technical Bulletin No. 1049: Systematic Statistical Procedures for Emission Factor Development

PDF , Source: Technical Bulletins Published: 09/2018 View Abstract

Abstract: This report describes a systematic statistical approach developed by NCASI to estimate emission factors from quality assured emissions and process data generated at forest products manufacturing facilities. The approach is designed to treat run-by-run data as well as data consisting of individual source averages. Key methodological steps implemented in the approach include the removal of suspiciously high non-detects (data below the reporting detection level), the identification and removal of potential statistical outliers, and the generation of summary statistics using a variety of robust estimators tailored to handle data sets containing a significant fraction of non-detects. The approach has been fully automated using a computer program that relies on Microsoft Access® to handle thousands of data sets and the R software to perform advanced statistical calculations. KEYWORDS: Statistics, data treatment, statistical analysis, emissions, emission factors, outliers, non-detects, censored data, Kaplan-Meier, Regression on Order Statistics, Maximum Likelihood Estimator, R

Technical Bulletin No. 1048: NCASI Studies on Train Blank (Zero) Bias, Best Practices, and Detection Limits for USEPA Method 202

PDF , Source: Technical Bulletins Published: 09/2018 View Abstract

Abstract: Responding to an immediate need to adequately quantify the train blank/zero bias of EPA Method 202 used to measure condensable PM (CPM), NCASI carried out three train blank studies (one in the laboratory and two under field conditions, 10 replicates per study) to evaluate the efficacy of the US Environmental Protection Agency (USEPA) suggested best practices for reducing systematic bias in the performance of EPA Method 202. These studies incorporated best practices and were carried out on the same source where a previous train blank study (8 replicates) was carried out by NCASI, prior to development of best practices. All train blanks were collected per NCASI’s train blank protocol, developed to accurately assess the level of non-flue-gas related residue bias (zero bias) associated with performance of PM sampling methods. NCASI’s train blank protocol has been acknowledged by EPA as a more appropriate methodology for determining zero bias; EPA incorporated NCASI’s train blank protocol into their suggested best practices for Method 202. KEYWORDS: Condensable PM, Condensible PM, CPM, Method 201A, Method 202, Method 202 best practices, NCASI train blank protocol, particulate emissions, particulate matter, PM, PM10, PM2.5, primary PM2.5, systematic bias, zero bias

Technical Bulletin No. 1047: Performance Evaluation of Nutrient Test Kits for Use with Pulp and Paper Mill Wastewaters

PDF , Source: Technical Bulletins Published: 05/2018 View Abstract

Abstract: NCASI performed a single laboratory evaluation of selected nutrient test kits in biologically treated wastewaters from a variety of pulp and paper mills using the manufacturer’s prescribed methodologies in parallel with established Environmental Protection Agency reference methods. Test methods evaluated included those for ammonia, nitrate-nitrite, total nitrogen, reactive orthophosphate, and total phosphorus. The test kits assessed were all from Hach Company and employed colorimetric determinative steps. This report provides information describing accuracy and precision margins, minimum detection and quantitation limits, reproducibility in industry wastewaters, directions for mitigating interferences, and method troubleshooting. With few exceptions, the test kit methods assessed yielded acceptable results for determinations of nutrients in pulp and paper wastewater when applied to samples within the working ranges of the methods and if consistently applied in accordance the manufacturer’s procedures. However, some potential matrix-specific interferences were noted and matrices not previously assessed should be evaluated to determine method accuracy and precision.

Technical Bulletin No. 1046: Model-Based Forecasts of North American Forest Growth: A Review

PDF , Source: Technical Bulletins Published: 01/2018 View Abstract

Abstract: In constantly changing environmental conditions, planning for forest management goals and projecting wood supplies becomes complicated. Possible changes in precipitation, temperature, and CO2 can affect tree growth substantially and potential effects differ by species and region. However, integration of potential forest growth responses to these factors can be achieved using models. Because of the need to understand the range of forest growth forecasts and the strengths and limitations of different modeling approaches, results from 18 studies of forecasted forest responses over coming decades were summarized. Some models used statistical relationships between tree rings and climate to forecast growth responses to potential future climate, some simulated net photosynthesis of a standard forest canopy, and many used tree or stand growth models at various levels of mechanistic detail. In general, models that included CO2 responses predicted enhanced forest growth by 2100 across most of the commercial timberland areas of the US and Canada. For modest warming, most models showed growth enhancement in most regions. For hotter scenarios, many models and regions showed even more growth enhancement, but some regions such as the Southwest, mountain West, and southwestern Canada were predicted to experience drought stress, although projections in these regions were variable. Young stands, angiosperms, and early-successional species were predicted to exhibit the most positive responses. As a result, commercial harvest ages might be accelerated by several years, depending on species. Some simulations for the Midwest and Northeast US predicted a doubling or more of net primary productivity; other studies show a lesser response. Models that did not include mechanisms of CO2 fertilization showed positive growth responses in limited cases and generally showed growth declines. There also was evidence indicating potential spread of forest into woodland at shrub or prairie ecotones.

Technical Bulletin No. 1045: Forest Growth Trends in the United States and Canada

PDF , Source: Technical Bulletins Published: 01/2018 View Abstract

Abstract: Reports of changes over the past century in factors such as temperature, precipitation, fire regimes, ozone, atmospheric CO2, and nitrogen deposition have led to questions about forest growth over this same time period. Determining changes in forest growth over long intervals is complicated by constantly changing growth conditions due to tree maturation, stand self-thinning, disturbance, fires, and other factors. Because a comprehensive review is lacking, results from publications examining forest growth trends in the United States and Canada over the past 100 years were evaluated. Reviewed papers used multiple sources of data, including remote sensing, permanent plots, growth models, tree ring analysis, and historical photography, to evaluate forest growth trends. In the Pacific Northwest (including British Columbia), the entire eastern US, and eastern Canada, reviewed publications report medium to strong growth enhancement based on a variety of data types over periods exceeding 100 years in some cases. For the inland West, historical photography shows clear densification and expansion of Ponderosa pine (Pinus ponderosa) forest across the region. However, a recent drought, probably linked to ocean cycles, has caused a growth setback, especially in the Southwest. In western Canada and Alaska, results are mixed. Studies have found forest expansion both upslope and down into grassland in many areas of the boreal zone. On the other hand, aspen (Populus tremuloides) dieback has been noted due to recent drought in these same forests. Studies using remote sensing and inventory data present mixed results in this region, with disagreement between studies and methods as well as probable heterogeneous responses. Factors identified as the cause of enhanced growth varied by region, but included reduced fire incidence, rising CO2 concentrations, N deposition, increased precipitation, and warming temperatures.

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