Abstract. We present a systematic comparison of tropospheric NO2 from 17 global atmospheric chemistry models with three state-of-the-art retrievals from the Global Ozone Monitoring Experiment (GOME) for the year 2000. The models used constant anthropogenic emissions from IIASA/EDGAR3.2 and monthly emissions from biomass burning based on the 1997–2002 average carbon emissions from the Global Fire Emissions Database (GFED). Model output is analyzed at 10:30 local time, close to the overpass time of the ERS-2 satellite, and collocated with the measurements to account for sampling biases due to incomplete spatiotemporal coverage of the instrument. We assessed the importance of different contributions to the sampling bias: correlations on seasonal time scale give rise to a positive bias of 30–50% in the retrieved annual means over regions dominated by emissions from biomass burning. Over the industrial regions of the eastern United States, Europe and eastern China the retrieved annual means have a negative bias with significant contributions (between −25% and +10% of the NO2 column) resulting from correlations on time scales from a day to a month. We present global maps of modeled and retrieved annual mean NO2 column densities, together with the corresponding ensemble means and standard deviations for models and retrievals. The spatial correlation between the individual models and retrievals are high, typically in the range 0.81–0.93 after smoothing the data to a common resolution. On average the models underestimate the retrievals in industrial regions, especially over eastern China and over the Highveld region of South Africa, and overestimate the retrievals in regions dominated by biomass burning during the dry season. The discrepancy over South America south of the Amazon disappears when we use the GFED emissions specific to the year 2000. The seasonal cycle is analyzed in detail for eight different continental regions. Over regions dominated by biomass burning, the timing of the seasonal cycle is generally well reproduced by the models. However, over Central Africa south of the Equator the models peak one to two months earlier than the retrievals. We further evaluate a recent proposal to reduce the NOx emission factors for savanna fires by 40% and find that this leads to an improvement of the amplitude of the seasonal cycle over the biomass burning regions of Northern and Central Africa. In these regions the models tend to underestimate the retrievals during the wet season, suggesting that the soil emissions are higher than assumed in the models. In general, the discrepancies between models and retrievals cannot be explained by a priori profile assumptions made in the retrievals, neither by diurnal variations in anthropogenic emissions, which lead to a marginal reduction of the NO2 abundance at 10:30 local time (by 2.5–4.1% over Europe). Overall, there are significant differences among the various models and, in particular, among the three retrievals. The discrepancies among the retrievals (10–50% in the annual mean over polluted regions) indicate that the previously estimated retrieval uncertainties have a large systematic component. Our findings imply that top-down estimations of NOx emissions from satellite retrievals of tropospheric NO2 are strongly dependent on the choice of model and retrieval.

. 1989. The effect of munricipal wastewater irrigation and rate of N fertilization on petiole composition, yield and quality of'Okanagan Riesling' grapes. Can. J. Plant Sci. 69: 1285-1294. Okanagan Riesling(Vitis sp.) vines, planted on a sandy soil in 1983, were trickle irrigated with municipal wastewater or well water and with each source of water there were 3 rates of Nfertilization (0, 17 and 34 g N as NH4NO, vine-l y-r), [1984][1985][1986][1987]. The zero-N treatment was increased to 8.5 g N vine-r in [1986][1987]

No abstract

Leaching under intense irrigation and nitrogen fertilization has reduced soil basic cation concentrations and soil pH in irrigated apple orchards. The objective of this study was to measure the effects of N fertilizer and grass cover vs. clean cultivation on Ca, Mg, and K leaching, and to determine the changes in concentrations of these cations in soil and leaf and fruit tissue of ‘McIntosh’ apple trees (Malus domestica Borkh.). Twelve lysimeters, each containing an Osoyoos sandy loam soil and a single ‘McIntosh’ apple tree, have been monitored for Ca, Mg, and K concentration of soil, drainage water, and tree leaves and fruit from 1976 to 1980. Lysimeter treatments included factorial combinations of Kentucky bluegrass (Poa pratensis) and clean cultivation and two N fertilization rates [162 (N1) and 324 kg N ha−1 year−1 (N2) as NH4NO3]. Clean cultivation had the greatest effect on cation leaching with significantly higher Ca and Mg concentrations and higher Ca, Mg, and K losses frequently measured in drainage from these plots. By 1981, exchangeable Ca, Mg, and soil pH at the 0‐ to 0.10‐m soil depth in the cultivated plots had declined by 4.3 mmol kg−1, 2.2 mmol kg−1, and 0.3 units, respectively, relative to the grass plots. Drainage from N2 relative to N1 lysimeters had a significantly higher Mg concentration for 4 years but significantly higher Ca and Mg loss rates in only 1 year because of lack of differences in drainage volumes between N2 and N1 plots. Neither the cultivation or fertilizer treatments had altered Ca, Mg, or K concentration of McIntosh fruit or foliage in 4 years. For all lysimeters, Ca and Mg leached more rapidly than K. Annual losses over all treatments, 1976 through 1980, averaged 387 kg Ca ha−1, 118 kg Mg ha−1, and 44 kg K ha−1. Such leaching would eventually lead to enrichment of local soils with K relative to Mg and Ca. This is undesirable since McIntosh trees are susceptible to Mg deficiency and K:Ca antagonism. Therefore, periodic additions of Ca and Mg as through dolomitic liming should be considered for these orchards. Also, K fertilization accelerates existing trends to relative enrichment of these soils with K.

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