Sze Sai-tim. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 77-82). / Abstracts in English and Chinese. / Acknowledgment --- p.i / Abstract (English) --- p.ii / Abstract (Chinese) --- p.iii / List of Figures --- p.iv / List of Tables --- p.v / Chapter 1. --- INTRODUCTION / Chapter 1.1 --- Air pollution in Hong Kong --- p.1 / Chapter 1.2 --- Chemical speciation of carbon in air particulates --- p.3 / Chapter 1.3 --- Carbonaceous compounds in air and their harmful effects --- p.6 / Chapter 1.4 --- Review of analytical techniques for carbon determination --- p.14 / Chapter 1.5 --- Research objective --- p.18 / Chapter 1.6 --- Brief description of the project --- p.20 / Chapter 2. --- INSTRUMENTATION AND THEORY / Chapter 2.1 --- Thermal-optical-FID method --- p.21 / Chapter 2.2 --- Combustion-NDIR method --- p.27 / Chapter 2.3 --- Comparison between two methods --- p.28 / Chapter 2.4 --- Materials used for preparing standards --- p.30 / Chapter 2.5 --- Filter media for thermal analysis of carbon containing aerosols --- p.31 / Chapter 3. --- EXPERIMENTAL / Chapter 3.1 --- Instrumentation --- p.33 / Chapter 3.2 --- Apparatus --- p.33 / Chapter 3.3 --- Reagents --- p.35 / Chapter 3.4 --- Analysis time and operation temperature --- p.36 / Chapter 3.5 --- Procedures --- p.38 / Chapter 4. --- RESULTS AND DISCUSSION / Chapter 4.1 --- Particulate matter concentration in air --- p.43 / Chapter 4.2 --- Calibration --- p.43 / Chapter 4.3 --- Recovery study of total carbon in Standard Reference Material --- p.47 / Chapter 4.4 --- Study of filter deposit homogeneity --- p.50 / Chapter 4.5 --- Determination of total carbon in air particulates --- p.52 / Chapter 4.6 --- Further comparison of two methods by determination of total carbon in different sample type (river suspended solids) --- p.61 / Chapter 4.7 --- Repeatability of time of evolution and quantity of carbon determined by thermal optical-FID --- p.70 / Chapter 4.8 --- Reproducibility of measuring total carbon in PM2 5 and PM10 --- p.73 / Chapter 5. --- CONCLUSION --- p.75 / Chapter 6. --- REFERENCES --- p.77

Emissions inventories are an important tool, often built by governments, and used to manage emissions. To build an inventory of urban CO2 emissions and other fossil fuel combustion products in the urban atmosphere, an inventory of on-road traffic is required. In particular, a high resolution inventory is necessary to capture the local characteristics of transport emissions. These emissions vary widely due to the local nature of the fleet, fuel, and roads. Here we show a new model of ADT for the Portland, OR metropolitan region. The backbone is traffic counter recordings made by the Portland Bureau of Transportation at 7,767 sites over 21 years (1986-2006), augmented with PORTAL (The Portland Regional Transportation Archive Listing) freeway traffic count data. We constructed a regression model to fill in traffic network gaps using GIS data such as road class and population density. An EPA-supplied emissions factor was used to estimate transportation CO2 emissions, which is compared to several other estimates for the city's CO2 footprint.

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Moss dominated ecosystems are an important part of the global terrestrial carbon cycle. Over large areas, remote sensing can be useful to provide an improved understanding of these ecosystems. Two boreal mossess (Pleurozium and Sphagnum) were assessed using remote sensing based spectral vegetation indices for estimating biochemical capacity and photosynthetic efficiency by varying net photosynthesis rate via changes in water content. In the laboratory, changes in the normalized difference vegetation index (NDVI) and chlorophyll index coincided with declining photosynthetic capacity due to desiccation. This effect was more dramatic in Sphagnum. The photochemical reflectance index (PRI) did not vary with changes in CO2 supply as anticipated, possibly due to overriding effects of changing water content. The water band index (WBI) was strongly related to water content but this relationship showed an uncoupling in the field. Bi-directional reflectance measurements indicated what WBI was sensitive to sensor, sun, and moss surface slope angles. / xi, 110 leaves : ill. (some col.) ; 29 cm.

Wetlands exchange significant amounts of carbon dioxide (CO2) and methane (CH4)---two major greenhouse gases (GHG), and thus have significant impacts on the Earth's climate. In this study, fluxes of CO2 and CH4 were measured in a cattail-dominated marsh in Eastern Ontario, Canada. Eddy covariance measurements of net ecosystem CO2 exchange (NEE) revealed that the marsh was an annual sink of 264 g C m-2, and that growing season net CO2 fluxes were strongly correlated with vegetation biomass and leaf area index. Fluxes of CH4 were measured from water, soil and plants using closed chambers and resulted in a net annual area-weighted emission from the marsh of 206 g C m-2. Consequently, the net (CO2 + CH4) annual carbon (C) balance of this wetland corresponded to a sink of 58 g C m-2. A simple radiative forcing model based on the marsh CO 2 and CH4 emission patterns suggests that, despite the net carbon uptake, this wetland is contributing to atmospheric warming because of the large CH4 efflux. Future potential climate impacts of this marsh were evaluated using different emission scenarios that could result in response to climatic or environmental changes. Overall, short-term impacts are driven by CH4 emission rate, while the CO2 flux determines the impacts on longer time horizons. Uncertainties in predicting future wetland GHG balance arise from uncertain feedbacks and responses. Future alterations of the marsh GHG emission and uptake patterns resulting from land use or climatic changes could lead to a shift in the marsh C balance, showing the importance of wetland ecosystems in national and global C budgets and GHG-related political decisions.

Carbon dioxide and methane fluxes were measured between May 2003 and August 2004 on vegetated surfaces and pools of three peatlands located in the La Grande Riviere watershed, James Bay lowland, Quebec, Canada. Gas flux measurements were made using static chambers on a variety of sites in the three peatlands, chosen to represent the different biotypes present, from hummocks with water table position 35 cm below the surface to pools 100 cm deep. / Average CH4 fluxes for the different biotypes on vegetated surfaces sampled during summer 2003 ranged from 3.5 to 197 mg m-2 d-1 while summer 2004 average floating chamber pool fluxes ranged between 6.2 and 3165 mg CH4 m-2 d -1. Mean daily CH4 fluxes on vegetated surface are strongly correlated (r2 > 0.75) with summer average water table depth, greater fluxes occurring where water table is close to the surface. The vegetated surface CH4 fluxes were also correlated with peat temperature as fluxes increase with increasing peat temperature during the summer. / Most net ecosystem productivity values calculated for the different biotypes in the three peatlands showed release of CO2 during both early and mid growing season periods. An annual budget calculated for the LG2 peatland showed that the peatland emitted CO2 to the atmosphere at a rate of 0.77 g m-2 d-1. The overall release of CO 2 may have been caused in part by dry conditions in the peatlands during summer 2003, due to high temperature and low precipitation.

Beaver ponds are important parts of peatland landscapes and have high fluxes of CO2 and CH4. This study was undertaken in Mer Bleue Bog, Ontario, to determine the response of a beaver pond to drainage (lowering by 25 cm) as a sink or source of carbon. Plant distribution was changed in response to a new water table gradient. Each vegetation community and the remaining beaver pond were sampled for fluxes of CO2 and CH4 from mid-April to end-November, 1999, one year after the water table was lowered. / A flow-through chamber system was used to measure CO2 flux from vegetated sites. Mean daily CO2 flux ranged from 0.4--1.6 g CO2-C M-2 (positive denoting uptake from the atmosphere). Variations in CO2 flux amongst the sites along the gradient could not be related to differences in plant species composition, peat temperature, or water table. The mean daily CO2 emission measured by a static floating chamber on the pond area was -24.1 g CO2-C m-2. / A closed chamber was used to measure CH4 on vegetated sites. Daily CH4 fluxes ranged from 1 to -159 mg CH4-C m-2, increasing from the beaver pond margin to the open water surface. The water table explained 83% of the seasonal average CH 4 flux variability and the vegetation added another 11%. The mean daily CH4 flux measured by a static floating chamber on the pond area was -54 mg CH4-C m-2. / The seasonal measurements were integrated into an areal estimate of CO 2 and CH4 flux for the beaver pond area prior to and after drainage. The beaver pond area sequestered 96 g m-2 before drainage (104 g CO2-C m-2 and -8 g CH 4-C m-2), and the same area more than doubled the uptake to 231 g m-2 after being drained (233 g CO 2-C m-2 and -3 g CH4-C m -2).

CH$ sb4$ and CO$ sb2$ fluxes were measured in upland boreal forest soils, over the period May 16$ sp{ rm th}$ through Sept. 16$ sp{ rm th}$, 1994, among a variety of vegetation and drainage characteristics. Most upland soils consumed CH$ sb4$, (0.6 to $-$2.6 mg CH$ sb4$ m$ sp{-2}$ d$ sp{-1}$), and produced CO$ sb2$, (0.2 to 26.8 g CO$ sb2$ m$ sp{-2}$ d$ sp{-1}$). CH$ sb4$ consumption showed no seasonal trend, however CO$ sb2$ flux displayed an increasing rate until late August, after which flux rates began to decrease. Differences among the sites examined showed soil temperature and organic matter content to be the primary controls in predicting seasonal mean CH$ sb4$ flux rates. Similarly for CO$ sb2$ flux, soil temperature and C content proved to be the best predictors of seasonal mean differences among the range of sites examined. / Sites could be divided into 2 categories, strong CH$ sb4$ consuming and CO$ sb2$ producing sites, Gillam Aspen, Gillam Pine, OBS Aspen, Burn Moss, Palsa Birch, and YJP Dry and weak CH$ sb4$ consuming and CO$ sb2$ producing sites, Gillam Spruce, OBS Spruce, YJP Wet, Burn Spruce and Palsa Moss. The strong flux sites all exhibited similar trends in soil characteristics as they were the warmest, driest sites with faster nutrient cycling processes and thin ($ sim$2 to 10 cm) organic layers. The weak flux sites were colder, wetter, with slower nutrient cycling, and a thick organic/peat layer ($ sim$20 to 50 cm). The primary visual distinction between these two groups was the presence of a Sphagnum sp. ground cover, which was characteristic of weak CH$ sb4$ consuming and CO$ sb2$ producing sites.

Growth responses to climatic variables of red pine (Pinus resinosa Aiton) and Norway spruce (Picea abies L. Karst) were studied at the Morgan Arboretum, near Montreal, in southern Quebec, Canada (45$ sp circ$ 25$ sp prime$ N, 73$ sp circ$ 57$ sp prime$ W; 15.2 m above sea level). The relationships between climatic variables and basal area growth were examined using linear and quadratic models. Current and previous year's climatic variables were tested separately and in combination using multiple regression models. The best models explained 82% and 85% of the total variance of the growth of Norway spruce and red pine, respectively. The growth of both species was more associated with evapotranspiration than precipitation. The growth of Norway spruce was best explained by the current year's annual evapotranspiration (43%), while the growth of red pine was more related to previous year's August evapotranspiration (33%) at our site. / The JABOWA model was used to predict tree growth in hypothetical climates which could result from global climate changes. Based on literature, five treatments were applied: normal, and increases of 1, 3, 5, and 10$ sp circ$C. Comparison between the last (1983-1992) and next (1993-2002) ten years growth showed no significant differences between species when temperature was normal or increased by 1 and 3$ sp circ$C, but significant differences between species were observed when the temperature was increased by 5$ sp circ$C. Both species declined when the temperature was increased by 10$ sp circ$C. We concluded that Norway spruce is more sensitive to increases in atmospheric temperatures than red pine at our site.