摘要:

Detailed and accurate emissions inventories are essential for reliable computer dispersion model simulation of the behavior of chemically and radiatively important atmospheric species. Currently, model simulations of the atmosphere are limited by the paucity of quality emissions data for input. As a first step in providing internationally recognized emissions inventories, we list here the inventories that are extant, together with their spatial and temporal characteristics and a few interpretive comments. The only global emissions inventory we regard as good is that for chlorofluorocarbons. Those for CO2, CH4, NOx, SO2, reduced sulfur, and radon we regard as fair. In selected regions, the spatial resolution of emissions is well determined for CO2, CO, NOx, and SO2. The temporal resolution of existing inventories is almost uniformly poor. Much remains to be done to generate emissions inventories adequate to fully support computer models of regional and global chemistry and climate.

ISSN:0886-6236    

DOI:10.1029/92GB02793

年代:1993

数据来源: WILEY

摘要:

We took measurements of up to 30 gases in Arctic haze and in clean Arctic air. These data were obtained from some 500 flask samples taken on three expeditions of the Arctic Gas and Aerosol Sampling Program (AGASP 1, 2, and 3) during the spring of 1983, 1986, and 1989. Concentrations of many gases are significantly higher in the haze layers compared to outside the haze. To look for the possible origins of the haze, we used cluster analysis to derive regional signatures of trace gases at ground‐based sites in middle and high northern latitudes. Comparison of the regional signatures with concentrations observed in Arctic haze suggest that there are no significant contributions from North America but possible influences from Russia and eastern Europe. These conclusions complement results derived from the analysis of the Arctic aerosol chemistry. It is possible, however, that Arctic haze originates from the military, industrial, and mining activities within the Arctic circle, particularly from the Russian Koala peninsul

ISSN:0886-6236    

DOI:10.1029/92GB03003

年代:1993

数据来源: WILEY

摘要:

This paper explores the role that measurements of changes in atmospheric oxygen, detected through changes in the O2/N2ratio of air, can play in improving our understanding of the global carbon cycle. Simple conceptual models are presented in order to clarify the biological and physical controls on the exchanges of O2, CO2, N2, and Ar across the air‐sea interface and in order to clarify the relationships between biologically mediated fluxes of oxygen across the air‐sea interface and the cycles of organic carbon in the ocean. Predictions of large‐scale seasonal variations and gradients in atmospheric oxygen are presented. A two‐dimensional model is used to relate changes in the O2/N2ratio of air to the sources of oxygen from terrestrial and marine ecosystems, the thermal ingassing and outgassing of seawater, and the burning of fossil fuel. The analysis indicates that measurements of seasonal variations in atmospheric oxygen can place new constraints on the large‐scale marine biological productivity. Measurements of the north‐south gradient and depletion rate of atmospheric oxygen can help determine the rates and geographical distribution of the net storage of carbon in terrestrial

ISSN:0886-6236    

DOI:10.1029/92GB02733

年代:1993

数据来源: WILEY

摘要:

As soils are a likely candidate for the so called missing carbon sink, we explore the possible impact of CO2fertilization on the global humus inventory. For any given greening‐induced enhancement of plant growth, the increase in soil carbon inventory will depend on the spectrum of turnover times with respect to oxidation. Here we develop estimates of carbon turnover rates based on soil radiocarbon measurement

ISSN:0886-6236    

DOI:10.1029/92GB02938

年代:1993

数据来源: WILEY

摘要:

The growth‐promoting effects of the historical increase in the air's CO2content are not yet evident in tree‐ring records where yearly biomass additions are apportioned among all plant parts. When almost all new biomass goes into cambial enlargement, however, a growth increase of 60% or more is observed over the past two centuries. As a result, calibration of tree‐ring records of this nature with instrumental climate records may not be feasible because of such growth changes. However, climate signals prior to about the mid‐19th century may yet be discovered by calibrating such tree‐ring series with independently derived proxy climate records for th

ISSN:0886-6236    

DOI:10.1029/92GB02533

年代:1993

数据来源: WILEY

摘要:

A standardized global data set of soil horizon thicknesses and textures (particle size distributions) has been compiled from the Food and Agriculture Organization of the United Nations/United Nations Educational, Scientific, and Cultural Organization (FAO/UNESCO) Soil Map of the World, Vols. 2–10 [1971–1981]. This data set was developed for use by the improved land‐surface hydrology parameterization designed by Abramopoulos et al. [1988]for the Goddard Institute for Space Studies General Circulation Model II (GISS GCM). The data set specifies the top and bottom depths and the percent abundance of sand, silt, and clay of individual soil horizons in each of the 106 soil types cataloged for nine continental divisions. When combined with the World Soil Data File [Zobler, 1986], the result is a l°×l° global data set of variations in physical properties throughout the soil profile. These properties are important in the determination of water storage in individual soil horizons and exchange of water with the lower atmosphere within global climate models. We have used these data sets, in conjunction with the Matthews [1983]global vegetation data set and texture‐based estimates of available soil moisture, to calculate the global distributions of soil profile thickness, potential storage of water in the soil profile, potential storage of water in the root zone, and potential storage of water derived from soil texture. Comparisons with the water‐holding capacities used in the GISS Model II show that our derived values for potential storage of water are consistently larger than those previously used in the GISS GCM. Preliminary analyses suggest that incorporation of this data set into the GISS GCM has improved the model's performance by including more realistic variability in land surfac

ISSN:0886-6236    

DOI:10.1029/92GB01822

年代:1993

数据来源: WILEY

摘要:

Methane fluxes and vertical profiles of CH4mixing ratios were measured in different German soils both in situ and in soil cores. Atmospheric CH4was oxidized in the soil by microorganisms resulting in an average CH4flux of −1.39±1.5 μmol‐CH4m−2h−1. Methane deposition showed only a weak positive correlation (r2= 0.38) with soil temperature but a relatively strong negative correlation (r2= 0.61) with soil moisture indicating limitation of the CH4flux by gas transport. Diffusion experiments in soil cores showed that gas transport between atmosphere and soil was faster than microbial CH4oxidation. However, the diffusion from the gas‐filled soil pores to the CH4oxidizing microorganisms may have been limiting. The main CH4−oxidizing activity was located in a few centimeter thick subsurface soil layer at the top of the Ahhorizon, whereas no activity was found in the overlying O horizons and in deep soil below about 20‐cm depth. In contrast, the highest CO2production was found in the topmost O horizon. The effective diffusion coefficient of CH4in soil was determined using a method based on relaxation experiments with argon. The diffusion coefficient was used to model the CH4oxidation in soil cores from the vertical profiles of CH4mixing ratios. The thus calculated CH4oxidation rates and their localization in the soil profile compared fairly well with those determined directly from incubated soil samples. Fluxes were similar within a factor of 2–4 whether derived from the model, calculated from the measured CH4 oxidation rates of soil samples, or

ISSN:0886-6236    

DOI:10.1029/92GB02814

年代:1993

数据来源: WILEY

摘要:

The variability of methane flux with season, year, and habitat type was investigated in northern Minnesota peatlands from September 1988 through September 1990. Average daily fluxes calculated by integration of annual data for an open poor fen, an open bog, a forested bog hollow, a fen lagg in the forested bog and a forested bog hummock were 180,118, 38, 35, and 10 mg CH4m−2d−1, respectively. Fluxes among the five ecosystems were significantly different from one another, although emission from all sites was highest in July and lowest in March. Winter fluxes occurred in all sites but the fen lagg. There was no difference in fluxes measured from the same sites in the spring of 1986, 1989, or 1990, but summer fluxes were significantly higher in the wetter year of 1989 than in 1990, and a summer pulse in methane emission occurred in 1989 that was not seen the next year. Concentrations of methane in pore water, reflecting the seasonal balance of production, oxidation, and release, declined during the month of peak flux, then increased to levels of about 500 μM in December. Consistent spatial and temporal differences in flux could be ascribed to differences in water table, temperature, and peat nutrient status, although additional variability remained. Integration gave an annual average flux of 20 g CH4, m−2ot; for the three bog ecosystems and 39 g CH4, m−2for the two fen ecosystems. This gives an estimate of 1–2 Tg CH4, yr−1from peatlands in the Great Lake states of Minnesota, Wisconsin,

ISSN:0886-6236    

DOI:10.1029/92GB02299

年代:1993

数据来源: WILEY

摘要:

To understand why atmospheric methane is increasing worldwide, accurate estimates are needed of the global input from rice fields. We report greenhouse and laboratory studies over three growing seasons to isolate and control factors that might affect methane emission from rice paddies, including soil texture, added exogenous organic matter (OM), nitrogen and sulfate ion, and water management. Without added OM, methane production was relatively low, increasing during the growing season, and continuing after harvest, provided the soil remained water‐logged. If ground rice straw was added to the soil prior to planting, methane production began shortly after flooding, with an initial burst of the gas after 3 to 5 weeks, and then a gradual increase to a second peak later in the season (and after harvest), with rates considerably higher than in treatments without added O

ISSN:0886-6236    

DOI:10.1029/92GB02712

年代:1993

数据来源: WILEY

摘要:

In this paper we approach the problem of the origin of organic‐carbon‐rich sediments by using an integrated isotopic and organic geochemical study of the annual productivity/eutrophication cycle in the water column of Lake Greifen (Switzerland) and the historical expression of such cycles as found in the sediments. The Lake Greifen water column and sediment studies reveal that Δδ13C carbonate‐organic matter is correlated with the hydrogen indices (HI) of kerogens, explicable in terms of changing productivity and preservation of the organic matter, and the CO2budget of the water body. The lake model implies that, if high productivity in CO2limited surface waters (high nutrient/CO2ratio) was controlling the preservation of organic matter, a correlation between decreasing Δδ13C carbonate ‐organic matter and increasing HI values may be observed. In contrast, if low to moderate productivity in CO2unlimited surface waters (low nutrient/CO2ratio) where bottom water anoxia promotes the preservation of organic matter, a correlation between increasing Δδ13C carbonate‐organic matter and increasing HI values may be observed. Application of this model to two well known Jurassic sequences, gave a correlation of increasing HI values with decreasing Δδ13C carbonate‐organic matter for the Kimmeridge Clay Formation (United Kingdom), and increasing HI values with increasing Δδ13C carbonate organic matter for the early Toarcian shales (France). This suggests that the controlling factor of the former deposit was high primary bioproductivity and of the latter deposit anoxic bo

ISSN:0886-6236    

DOI:10.1029/92GB02831

年代:1993

数据来源: WILEY