In order to further understand atmospheric deposition of elemental carbon (EC) with respect to climate and plant impacts, dry and wet deposition of EC was investigated in a tropical deciduous forest, ...Sakaerat, Thailand. Micro-meteorological measurements and monthly sampling of PM2.5 aerosols were carried out continuously over one year in 2010 at the top of an experimental tower 38 m above the ground established in the forest. The dry deposition was estimated by the inferential method by using an empirical parameterization of aerosol deposition velocity. For measurement of wet deposition, biweekly sampling of EC directly filtrated from rainwater was carried out continuously over one year in 2010. EC concentration significantly increased during the period from January to March due to heavy biomass burning, and decreased during the period from June to September due to less biomass burning and the washout effect by rainfall. High deposition velocities were caused by high wind speed in February to April and also by both large displacement height and medium wind speed in May to July. Dry deposition increased during the period from February to April when the concentration and deposition velocity were both high, and decreased during the period from June to December when the concentration or deposition velocity was low. Wet deposition peaked in March because of the washout effect of high EC in the atmosphere of the late dry season. Wet deposition was somewhat high from August to October with increased rainfall. Both dry and wet deposition increased in the leafless season and decreased in the leafy season, respectively. The annual dry and wet depositions were estimated as 0.58 and 0.05 mg m−2 day−1, respectively. Taking the uncertainties of estimations into account, dry deposition was still significantly higher than wet deposition.
► We characterized the dry and wet deposition of elemental carbon in a tropical forest. ► The majority of elemental carbon deposition is due to the dry disposition process. ► Both dry and wet depositions of elemental carbon are high in the leafless season.
Abstract Objectives To investigate the progression of the clinical features from symptom onset to diagnosis in children with brain tumours. Design : Retrospective case note review. Patients: Sixty ...children with brain tumours: 27 patients from Nagoya University Hospital diagnosed between February 2004 and April 2008, and 33 patients from Anjo Kosei Hospital diagnosed between April 1995 and December 2008. Results: Various symptoms and signs were observed. The most common initial symptoms or signs were vomiting (24.1%), headache (17.2%), unsteadiness (10.3%), and paresis (10.3%). Sixteen patients were diagnosed based on the initial symptom or sign alone; six, at routine medical check-ups or had perinatal diagnosis; and the remaining 38, based on one or more additional features following the initial symptom. Nine of the 10 patients with headache as the initial symptom subsequently developed either vomiting (in seven) or unsteadiness with cranial nerve palsies (in two). Twelve of the 14 patients with vomiting as the initial symptom subsequently developed headache (in three), unsteadiness (in five), or other manifestations of increased intracranial pressure (in four). The remaining 14 had varied initial symptoms and combinations of symptoms and signs associated with the tumour location. The median pre-diagnosis symptomatic interval was 20.5 days. There was no significant difference in the median symptomatic interval between patients with headache or vomiting as the initial symptom and those with any neurological sign. Conclusion: Paediatric brain tumours present with various initial symptoms and signs. Many are diagnosed as additional symptoms or signs develop. The clinical features exhibit several patterns of progression, which are related to the tumour location.
Trees are recognized as a carbon reservoir, and precise and convenient methods for forest biomass estimation are required for adequate carbon management. Airborne light detection and ranging (LiDAR) ...is considered to be one of the solutions for large-scale forest biomass evaluation. To clarify the relationship between mean canopy height determined by airborne LiDAR and forest timber volume and biomass of cool-temperate forests in northern Hokkaido, Japan, we conducted LiDAR observations covering the total area of the Teshio Experimental Forest (225km2) of Hokkaido University and compared the results with ground surveys and previous studies. Timber volume and aboveground tree carbon content of the studied forest stands ranged from 101.43 to 480.40m3ha–1 and from 30.78 to 180.54MgC ha–1, respectively. The LiDAR mean canopy height explained the variation among stands well (volume: r2=0.80, RMSE=55.04m3ha–1; aboveground tree carbon content: r2=0.78, RMSE=19.10MgC ha–1) when one simple linear regression equation was used for all types (hardwood, coniferous, and mixed) of forest stands. The determination of a regression equation for each forest type did not improve the prediction power for hardwood (volume: r2=0.84, RMSE=62.66m3ha–1; aboveground tree carbon content: r2=0.76, RMSE=27.05MgC ha–1) or coniferous forests (volume: r2=0.75, RMSE=51.07m3ha–1; aboveground tree carbon content: r2=0.58, RMSE=19.00MgC ha–1). Thus, the combined regression equation that includes three forest types appears to be adequate for practical application to large-scale forest biomass estimation.
•We conducted large-scale (225km2) airborne LiDAR survey in northernmost Japan.•Timber volume and biomass was linearly correlated with the LiDAR mean canopy height.•Regression including all forest types was adequate for large-scale biomass estimation.
Stream and soil solution chemistry, fine root biomass and soil nitrogen processing before and after clear-cutting of trees and subsequent strip-cutting of understory vegetation, dwarf bamboo (
Sasa ...senanensis), were investigated to understand the effect of these disturbances on biogeochemical processes on forested watershed in northern Japan. Tree-cutting did not cause a significant increase of nitrate (NO
3
−) concentration in stream water during the growing season after the cutting. Subsequent
Sasa-cutting caused significant increase of stream NO
3
− concentration to ca. 15
μmol
L
−1. There was no significant change of stream pH following both cuttings. NO
3
− concentration in soil solution increased after both cutting, but the change of concentration was higher (>100
μmol
L
−1) after the
Sasa-cutting than after the tree-cutting. In a riparian conserved area, on the other hand, NO
3
− in soil solution remained low after tree-cutting, suggesting the riparian area acted as a NO
3
− sink after the tree-cutting. There was no significant change in total biomass of fine roots after the tree-cutting because of an increase in
Sasa root biomass despite a decrease in tree roots. The subsequent
Sasa-cutting caused a 50% decrease of fine root biomass compared to that in the un-cut
Sasa site. These results suggested that nitrogen uptake by
Sasa was very important in preventing nitrogen leaching after tree-cutting, and decline of this nitrogen uptake after
Sasa-cutting lead to marked NO
3
− leaching to the stream.
The present study aimed to elucidate the atmosphere-forest exchange of ammoniacal nitrogen (NHX-N) at a young larch ecosystem. NHX-N exchanges were measured at a remote site in northernmost Japan ...where 4-year-old larches were growing after a pristine forest had been clear-cut and subsequent dense dwarf bamboo (Sasa) had been strip-cut. The site was a clean area for atmospheric ammonia with mean concentrations of 0.38 and 0.11 μg N m⁻³ in snowless and snow seasons, respectively. However, there was a general net emission of NHX-N. The annual estimated emission of NHX-N of 4.8 kg N ha⁻¹ year⁻¹ exceeded the annual wet deposition of 2.4 kg N ha⁻¹ year⁻¹, but the weekly exchange fluxes may have been underestimated by 28-60%. The main cause of the ammonia loss from the young larch ecosystem was probably enhanced nitrogen supply stimulated by the cutting of the pristine forest and Sasa, in particular, the Sasa.
Isotopic composition and origin of snow over Siberia Kurita, Naoyuki; Sugimoto, Atsuko; Fujii, Yoshiyuki ...
Journal of Geophysical Research - Atmospheres,
16 July 2005, Letnik:
110, Številka:
D13
Journal Article
Recenzirano
The spatial isotopic distribution of the snowpack over Siberia, where winter temperatures are as cold as those of the polar regions, was observed by the Trans‐Siberian Snow Survey (TSSS) and ...Trans‐Verkhoyansk Snow Survey Expedition (TVSSE) in March 2000 and March 2001. The results show inland δD depletion and a slightly increasing deuterium excess value, d, in the snowpack over Siberia. To explore the relationship between source region variability and the isotopic composition of snow, a model simulation was performed that reproduced the observed isotopic composition of snow. Moisture sources for Siberian precipitation were estimated using the Center for Climate System Research/National Institute for Environmental Studies (CCSR/NIES) atmospheric general circulation model (AGCM). A simple isotopic model was used to evaluate the total isotopic changes during transport from the designated source region to the region of precipitation. The results showed that the variability of the contribution of each source to the snow results in large isotopic variability, and the fact that the model reproduced the observed inland depletion of δD in snowpack suggests that GCM‐predicted source contributions were verified by observed values. However, the modeled d values did not match observed d values over Siberia. Observations of d values in precipitation show an increase during autumn toward a maximum in late autumn and then a decrease during winter; however, the modeled d value reached a maximum in early autumn and decreased toward a minimum in winter. The simple isotope model does not consider additional moisture evaporation joining an airmass moving from a source region. Therefore the disagreement between the modeled and observed d values of snow suggests that moisture supplied from the land surface during transportation significantly contributes to autumn snow. The increased d values of Siberian snow show that evaporation from open water or from the soil surface, which are accompanied by isotopic fractionation, are more important than transpiration flux, which does not change the isotopic content. The contribution of land‐derived moisture that has evaporated from open water plays an important role in eastern Siberian snow.
Aerosol concentrations at the CC-Lag site in the Teshio Experimental Forest increased from winter to spring and sometimes showed extremely high values associated with Kosa and/or forest-fire events. ...The range and mean of the mass concentrations of aerosol chemical species were as follows: total particulate mass, 1.2–29, 5.0; elemental carbon, 0.061–2.2, 0.43; organic carbon, 0.059–3.5, 0.79; and sulfate, 0.12–6.2, 1.8 μg/m
3
. The total masses of the deposited particles on hybrid larch and on bamboo leaves were approximately 35 and 30 μg/cm
2
, respectively. The amounts of soil particles on the leaves were 6 μg/cm
2
for the upper part of hybrid larch, 2 μg/cm
2
for the lower part of hybrid larch, and 1 μg/ cm
2
for Sasa bamboo leaves. The amounts of deposited black carbon were 2.3 μg/cm
2
for the upper part of hybrid larch, 0.6 μg/cm
2
for the lower part of hybrid larch, and 0.2 μg/cm
2
for Sasa bamboo leaves. Half of the total deposited particular mass was attached on the hybrid larch; however, most of the total deposited mass was adhered on the Sasa bamboo leaves. Regardless of the species, there tend to be more deposited particles on the leaves in the upper part than in the lower part, with only a few meters height difference. Comparing the composition of the deposited particles to that of the atmospheric aerosols without any size cut, the fractions of water-soluble material sulfate and sea salt in the deposited aerosols were about one tenth and one hundredth lower than that in the aerosols, respectively. On the basis of the measured concentration and the deposited amount on leaves, the deposition velocity of black carbon was estimated to be approximately 0.5 cm/s.
Lake Mashu is the only lake that serves as a baseline station of the United Nations Global Environment Monitoring System/Water (GEMS/Water) Programme. In this study, the concentration of trace lead ...in lake-water samples was determined by solid-phase extraction/concentration-ICP-MS to clarify the depth vertical profiles of lead. The finding that the lead concentration in the lake water above the thermocline shows a higher value than that in the lake water below the thermocline means that the input of lead into the surface water occurs during the thermocline-stratification period. The isotopic ratios (208Pb/206Pb and 207Pb/206Pb) were measured to estimate the origin of the lead. The obtained lead isotopic ratios in the surface water samples are similar to the reported values of the lead emitted in Japan rather than those at the Eurasia continent. The quantitative and isotopic analytical results in this study suggest a potential input of anthropogenically derived lead, presumably originating in Japan, into the surface water of Lake Mashu via the atmosphere since there is no inflowing river to the lake.
To evaluate the effects on CO₂ exchange of clearcutting a mixed forest and replacing it with a plantation, 4.5 years of continuous eddy covariance measurements of CO₂ fluxes and soil respiration ...measurements were conducted in a conifer-broadleaf mixed forest in Hokkaido, Japan. The mixed forest was a weak carbon sink (net ecosystem exchange, -44 g C m⁻² yr⁻¹), and it became a large carbon source (569 g C m⁻² yr⁻¹) after clearcutting. However, the large emission in the harvest year rapidly decreased in the following 2 years (495 and 153 g C m⁻² yr⁻¹, respectively) as the gross primary production (GPP) increased, while the total ecosystem respiration (RE) remained relatively stable. The rapid increase in GPP was attributed to an increase in biomass and photosynthetic activity of Sasa dwarf bamboo, an understory species. Soil respiration increased in the 3 years following clearcutting, in the first year mainly owing to the change in the gap ratio of the forest, and in the following years because of increased root respiration by the bamboo. The ratio of soil respiration to RE increased from 44% in the forest to nearly 100% after clearcutting, and aboveground parts of the vegetation contributed little to the RE although the respiration chamber measurements showed heterogeneous soil condition after clearcutting.
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